Tik Z, PGF Manual For Version 3.0.1a
TikZ%2C%20PGF%20Manual%20for%20Version%203.0.1a
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Z
k
i
T
Tik Z
&
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P
PG
GF
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Manual for Version ..a
Manual for Version ..a
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Für meinen Vater, damit er noch viele schöne TEX-Graphiken erschaffen kann.
Till
Copyright 2007 to 2013 by Till Tantau
Permission is granted to copy, distribute and/or modify the documentation under the terms of the gnu Free
Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with
no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in
the section entitled gnu Free Documentation License.
Permission is granted to copy, distribute and/or modify the code of the package under the terms of the gnu
Public License, Version 2 or any later version published by the Free Software Foundation. A copy of the
license is included in the section entitled gnu Public License.
Permission is also granted to distribute and/or modify both the documentation and the code under the
conditions of the LaTeX Project Public License, either version 1.3 of this license or (at your option) any
later version. A copy of the license is included in the section entitled LATEX Project Public License.
2
The Tik Z and PGF Packages
Manual for version 3.0.1a
http://sourceforge.net/projects/pgf
Till Tantau∗
Institut für Theoretische Informatik
Universität zu Lübeck
August 29, 2015
Contents
1
I
2
Introduction
1.1
The Layers Below Tik Z . . . . . . . . . . .
1.2
Comparison with Other Graphics Packages
1.3
Utility Packages . . . . . . . . . . . . . . .
1.4
How to Read This Manual . . . . . . . . .
1.5
Authors and Acknowledgements . . . . . .
1.6
Getting Help . . . . . . . . . . . . . . . . .
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Tutorials and Guidelines
25
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26
27
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27
28
Tutorial: A Picture for Karl’s Students
2.1
Problem Statement . . . . . . . . . . . . . . . . . .
2.2
Setting up the Environment . . . . . . . . . . . . .
2.2.1
Setting up the Environment in LATEX . . .
2.2.2
Setting up the Environment in Plain TEX
2.2.3
Setting up the Environment in ConTEXt .
2.3
Straight Path Construction . . . . . . . . . . . . . .
2.4
Curved Path Construction . . . . . . . . . . . . . .
2.5
Circle Path Construction . . . . . . . . . . . . . . .
2.6
Rectangle Path Construction . . . . . . . . . . . . .
2.7
Grid Path Construction . . . . . . . . . . . . . . . .
2.8
Adding a Touch of Style . . . . . . . . . . . . . . .
2.9
Drawing Options . . . . . . . . . . . . . . . . . . .
2.10
Arc Path Construction . . . . . . . . . . . . . . . .
2.11
Clipping a Path . . . . . . . . . . . . . . . . . . . .
2.12
Parabola and Sine Path Construction . . . . . . . .
2.13
Filling and Drawing . . . . . . . . . . . . . . . . . .
2.14
Shading . . . . . . . . . . . . . . . . . . . . . . . . .
2.15
Specifying Coordinates . . . . . . . . . . . . . . . .
2.16
Intersecting Paths . . . . . . . . . . . . . . . . . . .
2.17
Adding Arrow Tips . . . . . . . . . . . . . . . . . .
2.18
Scoping . . . . . . . . . . . . . . . . . . . . . . . . .
2.19
Transformations . . . . . . . . . . . . . . . . . . . .
2.20
Repeating Things: For-Loops . . . . . . . . . . . .
2.21
Adding Text . . . . . . . . . . . . . . . . . . . . . .
2.22
Pics: The Angle Revisited . . . . . . . . . . . . . .
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29
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42
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∗ Editor of this documentation. Parts of this documentation have been written by other authors as indicated in these parts
or chapters and in Section 1.5.
3
3
4
5
6
7
II
Tutorial: A Petri-Net for Hagen
3.1
Problem Statement . . . . . . . . . . . . . . . . . .
3.2
Setting up the Environment . . . . . . . . . . . . .
3.2.1
Setting up the Environment in LATEX . . .
3.2.2
Setting up the Environment in Plain TEX
3.2.3
Setting up the Environment in ConTEXt .
3.3
Introduction to Nodes . . . . . . . . . . . . . . . . .
3.4
Placing Nodes Using the At Syntax . . . . . . . . .
3.5
Using Styles . . . . . . . . . . . . . . . . . . . . . .
3.6
Node Size . . . . . . . . . . . . . . . . . . . . . . .
3.7
Naming Nodes . . . . . . . . . . . . . . . . . . . . .
3.8
Placing Nodes Using Relative Placement . . . . . .
3.9
Adding Labels Next to Nodes . . . . . . . . . . . .
3.10
Connecting Nodes . . . . . . . . . . . . . . . . . . .
3.11
Adding Labels Next to Lines . . . . . . . . . . . . .
3.12
Adding the Snaked Line and Multi-Line Text . . . .
3.13
Using Layers: The Background Rectangles . . . . .
3.14
The Complete Code . . . . . . . . . . . . . . . . . .
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47
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56
Tutorial: Euclid’s Amber Version of the Elements
4.1
Book I, Proposition I . . . . . . . . . . . . . . . . . . . . . .
4.1.1
Setting up the Environment . . . . . . . . . . . . .
4.1.2
The Line AB . . . . . . . . . . . . . . . . . . . . .
4.1.3
The Circle Around A . . . . . . . . . . . . . . . . .
4.1.4
The Intersection of the Circles . . . . . . . . . . . .
4.1.5
The Complete Code . . . . . . . . . . . . . . . . .
4.2
Book I, Proposition II . . . . . . . . . . . . . . . . . . . . . .
4.2.1
Using Partway Calculations for the Construction of
4.2.2
Intersecting a Line and a Circle . . . . . . . . . . .
4.2.3
The Complete Code . . . . . . . . . . . . . . . . .
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D
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58
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65
Tutorial: Diagrams as Simple Graphs
5.1
Styling the Nodes . . . . . . . . . . . . . . . . . . . .
5.2
Aligning the Nodes Using Positioning Options . . . .
5.3
Aligning the Nodes Using Matrices . . . . . . . . . .
5.4
The Diagram as a Graph . . . . . . . . . . . . . . . .
5.4.1
Connecting Already Positioned Nodes . . .
5.4.2
Creating Nodes Using the Graph Command
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66
66
68
70
71
71
72
Tutorial: A Lecture Map for Johannes
6.1
Problem Statement . . . . . . . . . .
6.2
Introduction to Trees . . . . . . . . .
6.3
Creating the Lecture Map . . . . . .
6.4
Adding the Lecture Annotations . . .
6.5
Adding the Background . . . . . . . .
6.6
Adding the Calendar . . . . . . . . .
6.7
The Complete Code . . . . . . . . . .
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75
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86
Guidelines on Graphics
7.1
Planning the Time Needed for the Creation of Graphics .
7.2
Workflow for Creating a Graphic . . . . . . . . . . . . .
7.3
Linking Graphics With the Main Text . . . . . . . . . .
7.4
Consistency Between Graphics and Text . . . . . . . . .
7.5
Labels in Graphics . . . . . . . . . . . . . . . . . . . . .
7.6
Plots and Charts . . . . . . . . . . . . . . . . . . . . . .
7.7
Attention and Distraction . . . . . . . . . . . . . . . . .
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Installation and Configuration
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97
4
8
9
10
III
Installation
8.1
Package and Driver Versions . . . . . . . . . . . . . .
8.2
Installing Prebundled Packages . . . . . . . . . . . .
8.2.1
Debian . . . . . . . . . . . . . . . . . . . . .
8.2.2
MiKTeX . . . . . . . . . . . . . . . . . . . .
8.3
Installation in a texmf Tree . . . . . . . . . . . . . . .
8.3.1
Installation that Keeps Everything Together
8.3.2
Installation that is TDS-Compliant . . . . .
8.4
Updating the Installation . . . . . . . . . . . . . . . .
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98
98
98
98
99
99
99
99
99
Licenses and Copyright
9.1
Which License Applies? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2
The GNU Public License, Version 2 . . . . . . . . . . . . . . . . . . . . . . .
9.2.1
Preamble . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.2
Terms and Conditions For Copying, Distribution and Modification
9.2.3
No Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.3
The LATEX Project Public License, Version 1.3c 2006-05-20 . . . . . . . . . .
9.3.1
Preamble . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.3.2
Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.3.3
Conditions on Distribution and Modification . . . . . . . . . . . . .
9.3.4
No Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.3.5
Maintenance of The Work . . . . . . . . . . . . . . . . . . . . . . .
9.3.6
Whether and How to Distribute Works under This License . . . . .
9.3.7
Choosing This License or Another License . . . . . . . . . . . . . .
9.3.8
A Recommendation on Modification Without Distribution . . . . .
9.3.9
How to Use This License . . . . . . . . . . . . . . . . . . . . . . . .
9.3.10
Derived Works That Are Not Replacements . . . . . . . . . . . . .
9.3.11
Important Recommendations . . . . . . . . . . . . . . . . . . . . .
9.4
GNU Free Documentation License, Version 1.2, November 2002 . . . . . . .
9.4.1
Preamble . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.4.2
Applicability and definitions . . . . . . . . . . . . . . . . . . . . . .
9.4.3
Verbatim Copying . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.4.4
Copying in Quantity . . . . . . . . . . . . . . . . . . . . . . . . . .
9.4.5
Modifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.4.6
Combining Documents . . . . . . . . . . . . . . . . . . . . . . . . .
9.4.7
Collection of Documents . . . . . . . . . . . . . . . . . . . . . . . .
9.4.8
Aggregating with independent Works . . . . . . . . . . . . . . . . .
9.4.9
Translation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.4.10
Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.4.11
Future Revisions of this License . . . . . . . . . . . . . . . . . . . .
9.4.12
Addendum: How to use this License for your documents . . . . . .
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100
100
100
100
101
103
103
103
103
104
105
106
106
106
107
107
107
107
108
108
108
109
109
109
111
111
111
111
111
112
112
Supported Formats
10.1
Supported Input Formats: LATEX, Plain TEX, ConTEXt
10.1.1
Using the LATEX Format . . . . . . . . . . . .
10.1.2
Using the Plain TEX Format . . . . . . . . . .
10.1.3
Using the ConTEXt Format . . . . . . . . . .
10.2
Supported Output Formats . . . . . . . . . . . . . . . .
10.2.1
Selecting the Backend Driver . . . . . . . . .
10.2.2
Producing PDF Output . . . . . . . . . . . .
10.2.3
Producing PostScript Output . . . . . . . . .
10.2.4
Producing SVG Output . . . . . . . . . . . .
10.2.5
Producing Perfectly Portable DVI Output . .
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113
113
113
113
113
114
114
114
115
115
117
Tik Z ist kein Zeichenprogramm
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118
5
11
12
13
14
Design Principles
11.1
Special Syntax For Specifying Points . . .
11.2
Special Syntax For Path Specifications . .
11.3
Actions on Paths . . . . . . . . . . . . . .
11.4
Key-Value Syntax for Graphic Parameters
11.5
Special Syntax for Specifying Nodes . . . .
11.6
Special Syntax for Specifying Trees . . . .
11.7
Special Syntax for Graphs . . . . . . . . .
11.8
Grouping of Graphic Parameters . . . . . .
11.9
Coordinate Transformation System . . . .
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119
119
119
120
120
120
120
121
121
122
Hierarchical Structures: Package, Environments, Scopes, and
12.1
Loading the Package and the Libraries . . . . . . . . . . . . .
12.2
Creating a Picture . . . . . . . . . . . . . . . . . . . . . . . . .
12.2.1
Creating a Picture Using an Environment . . . . . .
12.2.2
Creating a Picture Using a Command . . . . . . . .
12.2.3
Handling Catcodes and the Babel Package . . . . . .
12.2.4
Adding a Background . . . . . . . . . . . . . . . . .
12.3
Using Scopes to Structure a Picture . . . . . . . . . . . . . . .
12.3.1
The Scope Environment . . . . . . . . . . . . . . . .
12.3.2
Shorthand for Scope Environments . . . . . . . . . .
12.3.3
Single Command Scopes . . . . . . . . . . . . . . . .
12.3.4
Using Scopes Inside Paths . . . . . . . . . . . . . . .
12.4
Using Graphic Options . . . . . . . . . . . . . . . . . . . . . .
12.4.1
How Graphic Options Are Processed . . . . . . . . .
12.4.2
Using Styles to Manage How Pictures Look . . . . .
Styles
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123
123
123
123
125
125
126
126
126
127
127
128
128
128
128
Specifying Coordinates
13.1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . .
13.2
Coordinate Systems . . . . . . . . . . . . . . . . . . . .
13.2.1
Canvas, XYZ, and Polar Coordinate Systems
13.2.2
Barycentric Systems . . . . . . . . . . . . . .
13.2.3
Node Coordinate System . . . . . . . . . . . .
13.2.4
Tangent Coordinate Systems . . . . . . . . .
13.2.5
Defining New Coordinate Systems . . . . . .
13.3
Coordinates at Intersections . . . . . . . . . . . . . . .
13.3.1
Intersections of Perpendicular Lines . . . . .
13.3.2
Intersections of Arbitrary Paths . . . . . . . .
13.4
Relative and Incremental Coordinates . . . . . . . . . .
13.4.1
Specifying Relative Coordinates . . . . . . . .
13.4.2
Rotational Relative Coordinates . . . . . . .
13.4.3
Relative Coordinates and Scopes . . . . . . .
13.5
Coordinate Calculations . . . . . . . . . . . . . . . . .
13.5.1
The General Syntax . . . . . . . . . . . . . .
13.5.2
The Syntax of Factors . . . . . . . . . . . . .
13.5.3
The Syntax of Partway Modifiers . . . . . . .
13.5.4
The Syntax of Distance Modifiers . . . . . . .
13.5.5
The Syntax of Projection Modifiers . . . . . .
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130
130
130
130
133
134
136
137
137
137
138
140
140
141
142
142
142
143
143
144
145
Syntax for Path Specifications
14.1
The Move-To Operation . . . . . . . .
14.2
The Line-To Operation . . . . . . . . .
14.2.1
Straight Lines . . . . . . . . .
14.2.2
Horizontal and Vertical Lines
14.3
The Curve-To Operation . . . . . . . .
14.4
The Rectangle Operation . . . . . . . .
14.5
Rounding Corners . . . . . . . . . . . .
14.6
The Circle and Ellipse Operations . . .
14.7
The Arc Operation . . . . . . . . . . .
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146
147
148
148
149
149
150
150
151
152
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14.8
14.9
14.10
14.11
14.12
14.13
14.14
14.15
14.16
14.17
14.18
14.19
14.20
15
16
The
The
The
The
The
The
The
The
The
The
The
The
The
Grid Operation . . . . . . .
Parabola Operation . . . .
Sine and Cosine Operation
SVG Operation . . . . . . .
Plot Operation . . . . . . .
To Path Operation . . . . .
Foreach Operation . . . . .
Let Operation . . . . . . .
Scoping Operation . . . . .
Node and Edge Operations
Graph Operation . . . . . .
Pic Operation . . . . . . .
PGF-Extra Operation . . .
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153
154
156
156
157
157
160
160
162
162
162
162
162
Actions on Paths
15.1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15.2
Specifying a Color . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15.3
Drawing a Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15.3.1
Graphic Parameters: Line Width, Line Cap, and Line Join
15.3.2
Graphic Parameters: Dash Pattern . . . . . . . . . . . . . .
15.3.3
Graphic Parameters: Draw Opacity . . . . . . . . . . . . . .
15.3.4
Graphic Parameters: Double Lines and Bordered Lines . . .
15.4
Adding Arrow Tips to a Path . . . . . . . . . . . . . . . . . . . . . .
15.5
Filling a Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15.5.1
Graphic Parameters: Fill Pattern . . . . . . . . . . . . . . .
15.5.2
Graphic Parameters: Interior Rules . . . . . . . . . . . . . .
15.5.3
Graphic Parameters: Fill Opacity . . . . . . . . . . . . . . .
15.6
Generalized Filling: Using Arbitrary Pictures to Fill a Path . . . . .
15.7
Shading a Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15.8
Establishing a Bounding Box . . . . . . . . . . . . . . . . . . . . . . .
15.9
Clipping and Fading (Soft Clipping) . . . . . . . . . . . . . . . . . . .
15.10 Doing Multiple Actions on a Path . . . . . . . . . . . . . . . . . . . .
15.11 Decorating and Morphing a Path . . . . . . . . . . . . . . . . . . . .
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164
164
165
165
166
167
169
169
170
170
171
172
173
173
174
175
177
178
180
Arrows
16.1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16.2
Where and When Arrow Tips Are Placed . . . . . . . . . . . . .
16.3
Arrow Keys: Configuring the Appearance of a Single Arrow Tip
16.3.1
Size . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16.3.2
Scaling . . . . . . . . . . . . . . . . . . . . . . . . . . .
16.3.3
Arc Angles . . . . . . . . . . . . . . . . . . . . . . . .
16.3.4
Slanting . . . . . . . . . . . . . . . . . . . . . . . . . .
16.3.5
Reversing, Halving, Swapping . . . . . . . . . . . . . .
16.3.6
Coloring . . . . . . . . . . . . . . . . . . . . . . . . . .
16.3.7
Line Styling . . . . . . . . . . . . . . . . . . . . . . . .
16.3.8
Bending and Flexing . . . . . . . . . . . . . . . . . . .
16.4
Arrow Tip Specifications . . . . . . . . . . . . . . . . . . . . . .
16.4.1
Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . .
16.4.2
Specifying Paddings . . . . . . . . . . . . . . . . . . .
16.4.3
Specifying the Line End . . . . . . . . . . . . . . . . .
16.4.4
Defining Shorthands . . . . . . . . . . . . . . . . . . .
16.4.5
Scoping of Arrow Keys . . . . . . . . . . . . . . . . . .
16.5
Reference: Arrow Tips . . . . . . . . . . . . . . . . . . . . . . .
16.5.1
Barbed Arrow Tips . . . . . . . . . . . . . . . . . . . .
16.5.2
Mathematical Barbed Arrow Tips . . . . . . . . . . . .
16.5.3
Geometric Arrow Tips . . . . . . . . . . . . . . . . . .
16.5.4
Caps . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16.5.5
Special Arrow Tips . . . . . . . . . . . . . . . . . . . .
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182
182
182
184
185
188
188
188
189
190
191
193
197
197
198
199
200
201
202
203
206
207
211
212
7
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17
18
19
Nodes and Edges
17.1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17.2
Nodes and Their Shapes . . . . . . . . . . . . . . . . . . . . . . . . . .
17.2.1
Syntax of the Node Command . . . . . . . . . . . . . . . . . .
17.2.2
Predefined Shapes . . . . . . . . . . . . . . . . . . . . . . . .
17.2.3
Common Options: Separations, Margins, Padding and Border
17.3
Multi-Part Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17.4
The Node Text . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17.4.1
Text Parameters: Color and Opacity . . . . . . . . . . . . . .
17.4.2
Text Parameters: Font . . . . . . . . . . . . . . . . . . . . . .
17.4.3
Text Parameters: Alignment and Width for Multi-Line Text .
17.4.4
Text Parameters: Height and Depth of Text . . . . . . . . . .
17.5
Positioning Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17.5.1
Positioning Nodes Using Anchors . . . . . . . . . . . . . . . .
17.5.2
Basic Placement Options . . . . . . . . . . . . . . . . . . . . .
17.5.3
Advanced Placement Options . . . . . . . . . . . . . . . . . .
17.5.4
Advanced Arrangements of Nodes . . . . . . . . . . . . . . . .
17.6
Fitting Nodes to a Set of Coordinates . . . . . . . . . . . . . . . . . . .
17.7
Transformations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17.8
Placing Nodes on a Line or Curve Explicitly . . . . . . . . . . . . . . .
17.9
Placing Nodes on a Line or Curve Implicitly . . . . . . . . . . . . . . .
17.10 The Label and Pin Options . . . . . . . . . . . . . . . . . . . . . . . . .
17.10.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17.10.2 The Label Option . . . . . . . . . . . . . . . . . . . . . . . . .
17.10.3 The Pin Option . . . . . . . . . . . . . . . . . . . . . . . . . .
17.10.4 The Quotes Syntax . . . . . . . . . . . . . . . . . . . . . . . .
17.11 Connecting Nodes: Using Nodes as Coordinates . . . . . . . . . . . . .
17.12 Connecting Nodes: Using the Edge Operation . . . . . . . . . . . . . .
17.12.1 Basic Syntax of the Edge Operation . . . . . . . . . . . . . .
17.12.2 Nodes on Edges: Quotes Syntax . . . . . . . . . . . . . . . . .
17.13 Referencing Nodes Outside the Current Picture . . . . . . . . . . . . .
17.13.1 Referencing a Node in a Different Picture . . . . . . . . . . .
17.13.2 Referencing the Current Page Node – Absolute Positioning .
17.14 Late Code and Late Options . . . . . . . . . . . . . . . . . . . . . . . .
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Rotation
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214
214
214
214
218
218
221
222
222
222
223
226
227
227
228
229
233
233
234
235
238
238
238
239
241
242
245
245
245
247
248
248
249
249
Pics: Small Pictures on Paths
18.1
Overview . . . . . . . . . . .
18.2
The Pic Syntax . . . . . . .
18.2.1
The Quotes Syntax
18.3
Defining New Pic Types . .
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251
251
251
255
255
Specifying Graphs
19.1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . .
19.2
Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . .
19.2.1
Concept: Node Chains . . . . . . . . . . . . . .
19.2.2
Concept: Chain Groups . . . . . . . . . . . . .
19.2.3
Concept: Edge Labels and Styles . . . . . . . .
19.2.4
Concept: Node Sets . . . . . . . . . . . . . . .
19.2.5
Concept: Graph Macros . . . . . . . . . . . . .
19.2.6
Concept: Graph Expressions and Color Classes
19.3
Syntax of the Graph Path Command . . . . . . . . . . .
19.3.1
The Graph Command . . . . . . . . . . . . . .
19.3.2
Syntax of Group Specifications . . . . . . . . .
19.3.3
Syntax of Chain Specifications . . . . . . . . .
19.3.4
Syntax of Node Specifications . . . . . . . . . .
19.3.5
Specifying Tries . . . . . . . . . . . . . . . . . .
19.4
Quick Graphs . . . . . . . . . . . . . . . . . . . . . . . .
19.5
Simple Versus Multi-Graphs . . . . . . . . . . . . . . . .
19.6
Graph Edges: Labeling and Styling . . . . . . . . . . . .
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257
257
258
258
259
260
261
261
261
262
262
263
265
267
272
273
275
276
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19.7
19.8
19.9
19.10
20
21
22
19.6.1
Options For All Edges Between Two Groups . . . . . . . . . .
19.6.2
Changing Options For Certain Edges . . . . . . . . . . . . . .
19.6.3
Options For Incoming and Outgoing Edges . . . . . . . . . .
19.6.4
Special Syntax for Options For Incoming and Outgoing Edges
19.6.5
Placing Node Texts on Incoming Edges . . . . . . . . . . . .
Graph Operators, Color Classes, and Graph Expressions . . . . . . . .
19.7.1
Color Classes . . . . . . . . . . . . . . . . . . . . . . . . . . .
19.7.2
Graph Operators on Groups of Nodes . . . . . . . . . . . . .
19.7.3
Graph Operators for Joining Groups . . . . . . . . . . . . . .
Graph Macros . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Online Placement Strategies . . . . . . . . . . . . . . . . . . . . . . . .
19.9.1
Manual Placement . . . . . . . . . . . . . . . . . . . . . . . .
19.9.2
Placement on a Grid . . . . . . . . . . . . . . . . . . . . . . .
19.9.3
Placement Taking Node Sizes Into Account . . . . . . . . . .
19.9.4
Placement On a Circle . . . . . . . . . . . . . . . . . . . . . .
19.9.5
Levels and Level Styles . . . . . . . . . . . . . . . . . . . . . .
19.9.6
Defining New Online Placement Strategies . . . . . . . . . . .
Reference: Predefined Elements . . . . . . . . . . . . . . . . . . . . . .
19.10.1 Graph Macros . . . . . . . . . . . . . . . . . . . . . . . . . . .
19.10.2 Group Operators . . . . . . . . . . . . . . . . . . . . . . . . .
19.10.3 Joining Operators . . . . . . . . . . . . . . . . . . . . . . . . .
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276
277
277
279
280
280
280
282
284
286
287
287
288
291
293
295
296
299
299
301
302
Matrices and Alignment
20.1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . .
20.2
Matrices are Nodes . . . . . . . . . . . . . . . . . . . . . .
20.3
Cell Pictures . . . . . . . . . . . . . . . . . . . . . . . . . .
20.3.1
Alignment of Cell Pictures . . . . . . . . . . . . .
20.3.2
Setting and Adjusting Column and Row Spacing
20.3.3
Cell Styles and Options . . . . . . . . . . . . . .
20.4
Anchoring a Matrix . . . . . . . . . . . . . . . . . . . . . .
20.5
Considerations Concerning Active Characters . . . . . . .
20.6
Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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305
305
305
306
306
307
309
311
312
312
Making Trees Grow
21.1
Introduction to the Child Operation . . . .
21.2
Child Paths and Child Nodes . . . . . . .
21.3
Naming Child Nodes . . . . . . . . . . . .
21.4
Specifying Options for Trees and Children
21.5
Placing Child Nodes . . . . . . . . . . . . .
21.5.1
Basic Idea . . . . . . . . . . . . .
21.5.2
Default Growth Function . . . .
21.5.3
Missing Children . . . . . . . . .
21.5.4
Custom Growth Functions . . . .
21.6
Edges From the Parent Node . . . . . . . .
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316
316
317
317
318
319
319
320
322
323
323
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Bar Plots
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326
326
326
327
327
328
329
331
333
Plots
22.1
22.2
22.3
22.4
22.5
22.6
22.7
22.8
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of Functions
Overview . . . . . . . . . . . . . . . . . . . . .
The Plot Path Operation . . . . . . . . . . . .
Plotting Points Given Inline . . . . . . . . . .
Plotting Points Read From an External File .
Plotting a Function . . . . . . . . . . . . . . .
Plotting a Function Using Gnuplot . . . . . .
Placing Marks on the Plot . . . . . . . . . . .
Smooth Plots, Sharp Plots, Jump Plots, Comb
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Plots and
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23
24
25
IV
26
27
Transparency
23.1
Overview . . . . . . . . . . . .
23.2
Specifying a Uniform Opacity
23.3
Blend Modes . . . . . . . . . .
23.4
Fadings . . . . . . . . . . . . .
23.4.1
Creating Fadings . .
23.4.2
Fading a Path . . . .
23.4.3
Fading a Scope . . .
23.5
Transparency Groups . . . . .
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338
338
338
340
342
342
344
346
347
Decorated Paths
24.1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24.2
Decorating a Subpath Using the Decorate Path Command . . . . . . .
24.3
Decorating a Complete Path . . . . . . . . . . . . . . . . . . . . . . . .
24.4
Adjusting Decorations . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24.4.1
Positioning Decorations Relative to the To-Be-Decorate Path
24.4.2
Starting and Ending Decorations Early or Late . . . . . . . .
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350
350
352
354
354
354
355
Transformations
25.1
The Different Coordinate Systems . . .
25.2
The XY- and XYZ-Coordinate Systems
25.3
Coordinate Transformations . . . . . .
25.4
Canvas Transformations . . . . . . . .
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357
357
357
358
362
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Graph Drawing
363
Introduction to Algorithmic Graph Drawing
26.1
What Is Algorithmic Graph Drawing? . . . . . . . .
26.2
Using the Graph Drawing System . . . . . . . . . .
26.3
Extending the Graph Drawing System . . . . . . .
26.4
The Layers of the Graph Drawing System . . . . .
26.5
Organisation of the Graph Drawing Documentation
26.6
Acknowledgements . . . . . . . . . . . . . . . . . .
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364
364
364
365
366
366
367
Graph Drawing in Tik Z
Choosing a Layout and a Library . . . . . . . . . . . . .
Graph Drawing Parameters . . . . . . . . . . . . . . . . .
Padding and Node Distances . . . . . . . . . . . . . . . .
Anchoring a Graph . . . . . . . . . . . . . . . . . . . . .
Orienting a Graph . . . . . . . . . . . . . . . . . . . . . .
Fine-Tuning Positions of Nodes . . . . . . . . . . . . . .
Packing of Connected Components . . . . . . . . . . . .
27.7.1
Ordering the Components . . . . . . . . . . . .
27.7.2
Arranging Components in a Certain Direction .
27.7.3
Aligning Components . . . . . . . . . . . . . .
27.7.4
The Distance Between Components . . . . . . .
27.8
Anchoring Edges . . . . . . . . . . . . . . . . . . . . . . .
27.9
Hyperedges . . . . . . . . . . . . . . . . . . . . . . . . . .
27.10 Using Several Different Layouts to Draw a Single Graph
27.10.1 Sublayouts . . . . . . . . . . . . . . . . . . . . .
27.10.2 Subgraph Nodes . . . . . . . . . . . . . . . . .
27.10.3 Overlapping Sublayouts . . . . . . . . . . . . .
27.11 Miscellaneous Options . . . . . . . . . . . . . . . . . . .
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368
368
369
370
373
376
379
380
381
382
383
387
388
389
390
390
391
394
394
Using
27.1
27.2
27.3
27.4
27.5
27.6
27.7
10
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28
29
30
31
Using Graph Drawing in PGF
28.1
Overview . . . . . . . . . . . . . . .
28.2
How Graph Drawing in PGF Works
28.2.1
Graph Drawing Scopes . .
28.3
Layout Scopes . . . . . . . . . . . .
28.4
Layout Keys . . . . . . . . . . . . .
28.5
Parameters . . . . . . . . . . . . . .
28.6
Events . . . . . . . . . . . . . . . .
28.7
Subgraph Nodes . . . . . . . . . . .
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397
397
397
398
401
401
403
403
404
Graph Drawing Layouts: Trees
29.1
The Tree Layouts . . . . . . . . . . . .
29.1.1
The Reingold–Tilford Layout
29.2
Specifying Missing Children . . . . . .
29.3
Spanning Tree Computation . . . . . .
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405
405
405
409
411
Graph Drawing Algorithms: Layered Layouts
30.1
The Modular Sugiyama Method . . . . . . .
30.2
Cycle Removal . . . . . . . . . . . . . . . . .
30.3
Layer Assignment (Node Ranking) . . . . .
30.4
Crossing Minimization (Node Ordering) . . .
30.5
Node Positioning (Coordinate Assignment) .
30.6
Edge Routing . . . . . . . . . . . . . . . . .
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415
415
417
418
418
419
419
Graph Drawing Algorithms: Force-Based Methods
31.1
Controlling and Configuring Force-Based Algorithms .
31.1.1
Start Configuration . . . . . . . . . . . . . . .
31.1.2
The Iterative Process and Cooling . . . . . .
31.1.3
Forces and Their Effects: Springs . . . . . . .
31.1.4
Forces and Their Effects: Electrical Repulsion
31.1.5
Coarsening . . . . . . . . . . . . . . . . . . .
31.2
Spring Layouts . . . . . . . . . . . . . . . . . . . . . . .
31.3
Spring Electrical Layouts . . . . . . . . . . . . . . . . .
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420
421
421
421
423
423
424
426
426
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32
Graph Drawing Algorithms: Circular Layouts
428
33
Graph Drawing Layouts: Phylogenetic Trees
33.1
Generating a Phylogenetic Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
33.2
Laying out the Phylogram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
430
430
432
34
Graph Drawing Algorithms: Edge Routing
435
35
The Algorithm Layer
35.1
Overview . . . . . . . . . . . . . . . . . . . . . . . . .
35.2
Getting Started . . . . . . . . . . . . . . . . . . . . .
35.2.1
The Hello World of Graph Drawing . . . . .
35.2.2
Declaring an Algorithm . . . . . . . . . . .
35.2.3
The Run Method . . . . . . . . . . . . . . .
35.2.4
Loading Algorithms on Demand . . . . . . .
35.2.5
Declaring Options . . . . . . . . . . . . . .
35.2.6
Adding Inline Documentation . . . . . . . .
35.2.7
Adding External Documentation . . . . . .
35.3
Namespaces and File Names . . . . . . . . . . . . . .
35.3.1
Namespaces . . . . . . . . . . . . . . . . . .
35.3.2
Defining and Using Namespaces and Classes
35.4
The Graph Drawing Scope . . . . . . . . . . . . . . .
35.5
The Model Classes . . . . . . . . . . . . . . . . . . .
35.5.1
Directed Graphs (Digraphs) . . . . . . . . .
35.5.2
Vertices . . . . . . . . . . . . . . . . . . . .
11
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436
436
437
437
438
438
439
439
440
440
442
442
443
444
445
445
450
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452
456
458
459
465
466
467
467
469
470
476
476
477
478
480
480
483
484
484
. . . . . . . . . . . . . . .
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From Scratch . . . . . . .
Adapting Existing Classes
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486
486
487
487
489
489
490
490
491
493
493
494
495
495
37
The Display Layer
37.1
Introduction: The Interplay of the Different Layers . . . . . . . . . . . . . . . . . . . .
37.2
An Example Display System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
37.3
The Interface to Display Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
496
496
497
498
38
The Binding Layer
38.1
Overview . . . . . . . . . . . . . . .
38.2
The Binding Class and the Interface
38.3
The Binding To PGF . . . . . . . .
38.4
An Example Binding Class . . . . .
504
504
504
507
507
35.6
35.7
35.8
35.9
36
35.5.3
Arcs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35.5.4
Edges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35.5.5
Collections . . . . . . . . . . . . . . . . . . . . . . . . . . .
35.5.6
Coordinates, Paths, and Transformations . . . . . . . . . .
35.5.7
Options and Data Storages for Vertices, Arcs, and Digraphs
35.5.8
Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Graph Transformations . . . . . . . . . . . . . . . . . . . . . . . . . .
35.6.1
The Layout Pipeline . . . . . . . . . . . . . . . . . . . . . .
35.6.2
Hints For Edge Routing . . . . . . . . . . . . . . . . . . . .
The Interface To Algorithms . . . . . . . . . . . . . . . . . . . . . . .
Examples of Implementations of Graph Drawing Algorithms . . . . .
35.8.1
The “Hello World” of Graph Drawing . . . . . . . . . . . . .
35.8.2
How To Generate Edges Inside an Algorithm . . . . . . . .
35.8.3
How To Generate Nodes Inside an Algorithm . . . . . . . .
Support Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35.9.1
Basic Functions . . . . . . . . . . . . . . . . . . . . . . . . .
35.9.2
Lookup Tables . . . . . . . . . . . . . . . . . . . . . . . . .
35.9.3
Computing Distances in Graphs . . . . . . . . . . . . . . . .
35.9.4
Priority Queues . . . . . . . . . . . . . . . . . . . . . . . . .
Writing Graph Drawing Algorithms in C
36.1
How C and TEX Communicate . . . . . . . . . . . . . .
36.2
Writing Graph Drawing Algorithms in C . . . . . . . .
36.2.1
The Hello World of Graph Drawing in C . . .
36.2.2
Documenting Algorithms Written in C . . . .
36.2.3
The Interface From C . . . . . . . . . . . . .
36.3
Writing Graph Drawing Algorithms in C++ . . . . . .
36.3.1
The Hello World of Graph Drawing in C++ .
36.3.2
The Interface From C++ . . . . . . . . . . .
36.4
Writing Graph Drawing Algorithms Using OGDF . . .
36.4.1
The Hello World of Graph Drawing in OGDF
36.4.2
The Hello World of Graph Drawing in OGDF
36.4.3
Documenting OGDF Algorithms . . . . . . .
36.4.4
The Interface From OGDF . . . . . . . . . .
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Core .
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V
Libraries
39
Angle Library
511
40
Arrow Tip Library
512
41
Automata Drawing Library
41.1
Drawing Automata . . . . . . . .
41.2
States With and Without Output
41.3
Initial and Accepting States . . .
41.4
Examples . . . . . . . . . . . . . .
42
510
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Babel Library
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513
513
514
514
516
518
12
43
Background Library
519
44
Calc Library
523
45
Calendar Library
45.1
Calendar Command . . . . . . . . . . . . . . .
45.1.1
Creating a Simple List of Days . . .
45.1.2
Adding a Month Label . . . . . . . .
45.1.3
Creating a Week List Arrangement .
45.1.4
Creating a Month List Arrangement
45.2
Arrangements . . . . . . . . . . . . . . . . . .
45.3
Month Labels . . . . . . . . . . . . . . . . . .
45.4
Examples . . . . . . . . . . . . . . . . . . . . .
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524
524
531
531
531
532
532
534
537
Chains
46.1
Overview . . . . . . . . . . . . . .
46.2
Starting and Continuing a Chain
46.3
Nodes on a Chain . . . . . . . . .
46.4
Joining Nodes on a Chain . . . .
46.5
Branches . . . . . . . . . . . . . .
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541
541
541
542
545
545
Circuit Libraries
47.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
47.1.1
A First Example . . . . . . . . . . . . . . . . . . . . . . . .
47.1.2
Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
47.1.3
Symbol Graphics . . . . . . . . . . . . . . . . . . . . . . . .
47.1.4
Annotations . . . . . . . . . . . . . . . . . . . . . . . . . . .
47.2
The Base Circuit Library . . . . . . . . . . . . . . . . . . . . . . . . .
47.2.1
Symbol Size . . . . . . . . . . . . . . . . . . . . . . . . . . .
47.2.2
Declaring New Symbols . . . . . . . . . . . . . . . . . . . .
47.2.3
Pointing Symbols in the Right Direction . . . . . . . . . . .
47.2.4
Info Labels . . . . . . . . . . . . . . . . . . . . . . . . . . .
47.2.5
Declaring and Using Annotations . . . . . . . . . . . . . . .
47.2.6
Theming Symbols . . . . . . . . . . . . . . . . . . . . . . . .
47.3
Logical Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
47.3.1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . .
47.3.2
Symbols: The Gates . . . . . . . . . . . . . . . . . . . . . .
47.3.3
Implementation: The Logic Gates Shape Library . . . . . .
47.3.4
Implementation: The US-Style Logic Gates Shape Library .
47.3.5
Implementation: The IEC-Style Logic Gates Shape Library
47.4
Electrical Engineering Circuits . . . . . . . . . . . . . . . . . . . . . .
47.4.1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . .
47.4.2
Symbols: Indicating Current Directions . . . . . . . . . . .
47.4.3
Symbols: Basic Elements . . . . . . . . . . . . . . . . . . .
47.4.4
Symbols: Diodes . . . . . . . . . . . . . . . . . . . . . . . .
47.4.5
Symbols: Contacts . . . . . . . . . . . . . . . . . . . . . . .
47.4.6
Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
47.4.7
Annotations . . . . . . . . . . . . . . . . . . . . . . . . . . .
47.4.8
Implementation: The EE-Symbols Shape Library . . . . . .
47.4.9
Implementation: The IEC-Style EE-Symbols Shape Library
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547
547
547
548
548
549
549
550
550
552
553
554
555
557
557
559
560
561
563
565
565
568
568
569
569
569
569
569
571
Decoration Library
48.1
Overview and Common Options
48.2
Path Morphing Decorations . .
48.2.1
Decorations Producing
48.2.2
Decorations Producing
48.3
Path Replacing Decorations . .
48.4
Marking Decorations . . . . . .
48.4.1
Overview . . . . . . .
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577
577
578
578
579
581
584
584
46
47
48
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. . . . . . . . . . . .
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Straight Line Paths
Curved Line Paths .
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. . . . . . . . . . . .
13
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48.5
48.6
48.7
Arbitrary Markings . . . . . . . . . . .
48.5.1
Arrow Tip Markings . . . . .
48.5.2
Footprint Markings . . . . . .
48.5.3
Shape Background Markings
Text Decorations . . . . . . . . . . . .
Fractal Decorations . . . . . . . . . . .
Diagram
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Drawing
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584
588
589
590
594
603
Library
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
605
605
605
606
49
Entity-Relationship
49.1
Entities . . . .
49.2
Relationships .
49.3
Attributes . .
50
Externalization Library
50.1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
50.2
Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . .
50.3
A Word About ConTEXt And Plain TEX . . . . . . . . . . . . .
50.4
Externalizing Graphics . . . . . . . . . . . . . . . . . . . . . . .
50.4.1
Support for Labels and References In External Files .
50.4.2
Customizing the Generated File Names . . . . . . . .
50.4.3
Remaking Figures or Skipping Figures . . . . . . . . .
50.4.4
Customizing the Externalization . . . . . . . . . . . .
50.4.5
Details About The Process . . . . . . . . . . . . . . .
50.5
Using External Graphics Without pgf Installed . . . . . . . . .
50.6
eps Graphics Export . . . . . . . . . . . . . . . . . . . . . . . .
50.7
Bitmap Graphics Export . . . . . . . . . . . . . . . . . . . . . .
50.8
Compatibility Issues . . . . . . . . . . . . . . . . . . . . . . . . .
50.8.1
References In External Pictures . . . . . . . . . . . . .
50.8.2
Compatibility With Other Libraries or Packages . . .
50.8.3
Compatibility With Bounding Box Restrictions . . . .
50.8.4
Interoperability With The Basic Layer Externalization
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607
607
607
607
607
609
610
611
613
617
617
618
618
619
619
619
620
620
51
Fading Library
621
52
Fitting Library
622
53
Fixed Point Arithmetic Library
53.1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
53.2
Using Fixed Point Arithmetic in PGF and Tik Z . . . . . . . . . . . . . . . . . . . . . .
625
625
625
54
Floating Point Unit Library
54.1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
54.2
Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
54.3
Comparison to the fixed point arithmetics library . . . . . . . . .
54.4
Command Reference and Programmer’s Manual . . . . . . . . . .
54.4.1
Creating and Converting Floats . . . . . . . . . . . . . .
54.4.2
Symbolic Rounding Operations . . . . . . . . . . . . . .
54.4.3
Math Operations Commands . . . . . . . . . . . . . . .
54.4.4
Accessing the Original Math Routines for Programmers
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627
627
627
628
628
628
631
632
634
Lindenmayer System Drawing Library
55.1
Overview . . . . . . . . . . . . . . . .
55.1.1
Declaring L-systems . . . .
55.2
Using Lindenmayer Systems . . . . .
55.2.1
Using L-Systems in PGF . .
55.2.2
Using L-Systems in Tik Z . .
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635
635
635
637
637
638
55
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56
Math
56.1
56.2
56.3
56.4
56.5
56.6
56.7
Library
Overview . . . . . . . . . . . . . . . . . . .
Assignment . . . . . . . . . . . . . . . . . .
Integers, “Real” Numbers, and Coordinates
Repeating Things . . . . . . . . . . . . . .
Branching Statements . . . . . . . . . . . .
Declaring Functions . . . . . . . . . . . . .
Executing Code Outside the Parser . . . .
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640
640
641
642
643
643
644
644
57
Matrix Library
57.1
Matrices of Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
57.2
End-of-Lines and End-of-Row Characters in Matrices of Nodes . . . . . . . . . . . . . .
57.3
Delimiters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
646
646
647
648
58
Mindmap Drawing Library
58.1
Overview . . . . . . . . . . . . . . . . . . . . . .
58.2
The Mindmap Style . . . . . . . . . . . . . . . .
58.3
Concepts Nodes . . . . . . . . . . . . . . . . . .
58.3.1
Isolated Concepts . . . . . . . . . . . .
58.3.2
Concepts in Trees . . . . . . . . . . . .
58.4
Connecting Concepts . . . . . . . . . . . . . . .
58.4.1
Simple Connections . . . . . . . . . . .
58.4.2
The Circle Connection Bar Decoration
58.4.3
The Circle Connection Bar To-Path .
58.4.4
Tree Edges . . . . . . . . . . . . . . .
58.5
Adding Annotations . . . . . . . . . . . . . . . .
650
650
650
651
651
652
654
654
655
656
657
658
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59
Paper Folding Diagrams Library
660
60
Pattern Library
60.1
Form-Only Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
60.2
Inherently Colored Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
666
666
666
61
Petri-Net Drawing Library
61.1
Places . . . . . . . . . .
61.2
Transitions . . . . . . .
61.3
Tokens . . . . . . . . .
61.4
Examples . . . . . . . .
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667
667
667
668
670
Plot Handler Library
62.1
Curve Plot Handlers .
62.2
Constant Plot Handlers
62.3
Comb Plot Handlers . .
62.4
Bar Plot Handlers . . .
62.5
Gapped Plot Handlers
62.6
Mark Plot Handler . .
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672
672
673
674
675
677
678
62
63
Plot Mark Library
681
64
Profiler Library
64.1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
64.2
Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
64.3
Defining Profiler Entries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
683
683
683
683
65
Shadings Library
686
15
66
67
68
Shadows Library
66.1
Overview . . . . . . . . . . . . . . . . . .
66.2
The General Shadow Option . . . . . . .
66.3
Shadows for Arbitrary Paths and Shapes
66.3.1
Drop Shadows . . . . . . . . . .
66.3.2
Copy Shadows . . . . . . . . .
66.4
Shadows for Special Paths and Nodes . .
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689
689
689
690
690
690
691
Shape Library
67.1
Overview . . . . . . . . . . . . .
67.2
Predefined Shapes . . . . . . . .
67.3
Geometric Shapes . . . . . . . .
67.4
Symbol Shapes . . . . . . . . . .
67.5
Arrow Shapes . . . . . . . . . .
67.6
Shapes with Multiple Text Parts
67.7
Callout Shapes . . . . . . . . . .
67.8
Miscellaneous Shapes . . . . . .
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693
693
693
694
709
717
723
729
733
Pictures
. . . . . .
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738
738
739
739
741
742
Spy Library: Magnifying Parts of
68.1
Magnifying a Part of a Picture
68.2
Spy Scopes . . . . . . . . . . .
68.3
The Spy Command . . . . . .
68.4
Predefined Spy Styles . . . . .
68.5
Examples . . . . . . . . . . . .
69
SVG-Path Library
70
To Path Library
70.1
Straight Lines
70.2
Move-Tos . . .
70.3
Curves . . . .
70.4
Loops . . . . .
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744
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745
745
745
745
748
71
Through Library
750
72
Tree Library
72.1
Growth Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
72.2
Edges From Parent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
751
751
753
73
Turtle Graphics Library
754
VI
Data Visualization
756
74
Introduction to Data Visualization
74.1
Concept: Data Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
74.2
Concept: Visualization Pipeline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
757
757
757
75
Creating Data Visualizations
75.1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
75.2
Concept: Data Points and Data Formats . . . . . . . . . . . .
75.3
Concept: Axes, Ticks, and Grids . . . . . . . . . . . . . . . . .
75.4
Concept: Visualizers . . . . . . . . . . . . . . . . . . . . . . .
75.5
Concept: Style Sheets and Legends . . . . . . . . . . . . . . .
75.6
Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
75.7
Advanced: Executing User Code During a Data Visualization
75.8
Advanced: Creating New Objects . . . . . . . . . . . . . . . .
759
759
759
760
761
761
762
766
767
16
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76
77
78
Providing Data for a Data Visualization
76.1
Overview . . . . . . . . . . . . . . . . .
76.2
Concepts . . . . . . . . . . . . . . . . .
76.3
Reference: Build-In Formats . . . . . .
76.4
Reference: Advanced Formats . . . . .
76.5
Advanced: The Data Parsing Process .
76.6
Advanced: Defining New Formats . . .
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769
769
769
769
771
773
775
Axes
77.1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
77.2
Basic Configuration of Axes . . . . . . . . . . . . . . . . . . . . . . . . .
77.2.1
Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
77.2.2
The Axis Attribute . . . . . . . . . . . . . . . . . . . . . . . . .
77.2.3
The Axis Attribute Range Interval . . . . . . . . . . . . . . . .
77.2.4
Scaling: The General Mechanism . . . . . . . . . . . . . . . . .
77.2.5
Scaling: Logarithmic Axes . . . . . . . . . . . . . . . . . . . . .
77.2.6
Scaling: Setting the Length or Unit Length . . . . . . . . . . .
77.2.7
Axis Label . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
77.2.8
Reference: Axis Types . . . . . . . . . . . . . . . . . . . . . . .
77.3
Axis Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
77.3.1
Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
77.3.2
Reference: Scientific Axis Systems . . . . . . . . . . . . . . . .
77.3.3
Reference: School Book Axis Systems . . . . . . . . . . . . . .
77.3.4
Advanced Reference: Underlying Cartesian Axis Systems . . .
77.4
Ticks and Grids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
77.4.1
Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
77.4.2
The Main Options: Tick and Grid . . . . . . . . . . . . . . . .
77.4.3
Semi-Automatic Computation of Tick and Grid Line Positions
77.4.4
Automatic Computation of Tick and Grid Line Positions . . . .
77.4.5
Manual Specification of Tick and Grid Line Positions . . . . . .
77.4.6
Styling Ticks and Grid Lines: Introduction . . . . . . . . . . .
77.4.7
Styling Ticks and Grid Lines: The Style and Node Style Keys .
77.4.8
Styling Ticks and Grid Lines: Styling Grid Lines . . . . . . . .
77.4.9
Styling Ticks and Grid Lines: Styling Ticks and Tick Labels . .
77.4.10 Styling Ticks and Grid Lines: Exceptional Ticks . . . . . . . .
77.4.11 Styling Ticks and Grid Lines: Styling and Typesetting a Value
77.4.12 Stacked Ticks . . . . . . . . . . . . . . . . . . . . . . . . . . . .
77.4.13 Reference: Basic Strategies . . . . . . . . . . . . . . . . . . . .
77.4.14 Advanced: Defining New Placement Strategies . . . . . . . . .
77.5
Advanced: Creating New Axis Systems . . . . . . . . . . . . . . . . . . .
77.5.1
Creating the Axes . . . . . . . . . . . . . . . . . . . . . . . . .
77.5.2
Visualizing the Axes . . . . . . . . . . . . . . . . . . . . . . . .
77.5.3
Visualizing Grid Lines . . . . . . . . . . . . . . . . . . . . . . .
77.5.4
Visualizing the Ticks and Tick Labels . . . . . . . . . . . . . .
77.5.5
Visualizing the Axis Labels . . . . . . . . . . . . . . . . . . . .
77.5.6
The Complete Axis System . . . . . . . . . . . . . . . . . . . .
77.5.7
Using the New Axis System Key . . . . . . . . . . . . . . . . .
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777
777
777
777
778
779
779
782
782
784
784
785
785
786
789
790
791
791
792
793
794
797
799
799
800
802
803
804
805
808
809
810
810
811
814
816
819
820
821
Visualizers
78.1
Overview . . . . . . . . . . . . . . . . .
78.2
Usage . . . . . . . . . . . . . . . . . . .
78.2.1
Using a Single Visualizer . . .
78.2.2
Using Multiple Visualizers . .
78.2.3
Styling a Visualizer . . . . . .
78.3
Reference: Basic Visualizers . . . . . .
78.3.1
Visualizing Data Points Using
78.3.2
Visualizing Data Points Using
78.4
Advanced: Creating New Visualizers .
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822
822
822
822
823
824
826
826
828
829
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Lines
Marks
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17
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79
Style
79.1
79.2
79.3
79.4
79.5
79.6
79.7
79.8
79.9
80
81
VII
82
Sheets and Legends
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Concepts: Style Sheets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Concepts: Legends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Usage: Style Sheets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
79.4.1
Picking a Style Sheet . . . . . . . . . . . . . . . . . . . . . . . . . .
79.4.2
Creating a New Style Sheet . . . . . . . . . . . . . . . . . . . . . .
79.4.3
Creating a New Color Style Sheet . . . . . . . . . . . . . . . . . . .
Reference: Style Sheets for Lines . . . . . . . . . . . . . . . . . . . . . . . . .
Reference: Style Sheets for Scatter Plots . . . . . . . . . . . . . . . . . . . .
Reference: Color Style Sheets . . . . . . . . . . . . . . . . . . . . . . . . . .
Usage: Labeling Data Sets Inside the Visualization . . . . . . . . . . . . . .
79.8.1
Placing a Label Next to a Data Set . . . . . . . . . . . . . . . . . .
79.8.2
Connecting a Label to a Data Set via a Pin . . . . . . . . . . . . .
Usage: Labeling Data Sets Inside a Legend . . . . . . . . . . . . . . . . . . .
79.9.1
Creating Legends and Legend Entries . . . . . . . . . . . . . . . .
79.9.2
Rows and Columns of Legend Entries . . . . . . . . . . . . . . . .
79.9.3
Legend Placement: The General Mechanism . . . . . . . . . . . . .
79.9.4
Legend Placement: Outside to the Data Visualization . . . . . . .
79.9.5
Legend Placement: Inside to the Data Visualization . . . . . . . .
79.9.6
Legend Entries: General Styling . . . . . . . . . . . . . . . . . . . .
79.9.7
Legend Entries: Styling the Text Node . . . . . . . . . . . . . . . .
79.9.8
Legend Entries: Text Placement . . . . . . . . . . . . . . . . . . .
79.9.9
Advanced: Labels in Legends and Their Visualizers . . . . . . . . .
79.9.10 Reference: Label in Legend Visualizers for Lines and Scatter Plots
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832
832
832
833
834
834
834
837
837
839
840
841
842
844
845
846
848
851
852
854
856
856
857
857
859
Polar Axes
80.1
Overview . . . . . . . . . . . . . . . . . . . . .
80.2
Scientific Polar Axis System . . . . . . . . . .
80.2.1
Tick Placements . . . . . . . . . . .
80.2.2
Angle Ranges . . . . . . . . . . . . .
80.3
Advanced: Creating a New Polar Axis System
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864
864
865
866
867
871
The Data Visualization Backend
81.1
Overview . . . . . . . . . . . . .
81.2
The Rendering Pipeline . . . . .
81.3
Usage . . . . . . . . . . . . . . .
81.4
The Mathematical Micro-Kernel
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873
873
873
873
873
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.
Utilities
874
Key Management
82.1
Introduction . . . . . . . . . . . . . . . . . . . . . .
82.1.1
Comparison to Other Packages . . . . . .
82.1.2
Quick Guide to Using the Key Mechanism
82.2
The Key Tree . . . . . . . . . . . . . . . . . . . . .
82.3
Setting Keys . . . . . . . . . . . . . . . . . . . . . .
82.3.1
First Char Syntax Detection . . . . . . . .
82.3.2
Default Arguments . . . . . . . . . . . . .
82.3.3
Keys That Execute Commands . . . . . .
82.3.4
Keys That Store Values . . . . . . . . . .
82.3.5
Keys That Are Handled . . . . . . . . . .
82.3.6
Keys That Are Unknown . . . . . . . . .
82.3.7
Search Paths And Handled Keys . . . . .
82.4
Key Handlers . . . . . . . . . . . . . . . . . . . . .
82.4.1
Handlers for Path Management . . . . . .
82.4.2
Setting Defaults . . . . . . . . . . . . . . .
82.4.3
Defining Key Codes . . . . . . . . . . . .
18
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875
875
875
875
876
877
878
880
880
882
882
883
884
885
885
885
885
82.5
82.6
82.4.4
Defining Styles . . . . . . . . . . . . . . . . .
82.4.5
Defining Value-, Macro-, If- and Choice-Keys
82.4.6
Expanded and Multiple Values . . . . . . . .
82.4.7
Handlers for Forwarding . . . . . . . . . . . .
82.4.8
Handlers for Testing Keys . . . . . . . . . . .
82.4.9
Handlers for Key Inspection . . . . . . . . . .
Error Keys . . . . . . . . . . . . . . . . . . . . . . . . .
Key Filtering . . . . . . . . . . . . . . . . . . . . . . . .
82.6.1
Starting With An Example . . . . . . . . . .
82.6.2
Setting Filters . . . . . . . . . . . . . . . . . .
82.6.3
Handlers For Unprocessed Keys . . . . . . . .
82.6.4
Family Support . . . . . . . . . . . . . . . . .
82.6.5
Other Key Filters . . . . . . . . . . . . . . . .
82.6.6
Programmer Interface . . . . . . . . . . . . .
82.6.7
Defining Own Filters Or Filter Handlers . . .
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887
888
890
890
892
893
893
894
894
894
896
896
898
899
899
83
Repeating Things: The Foreach Statement
84
Date and Calendar Utility Macros
84.1
Handling Dates . . . . . . . . . . .
84.1.1
Conversions Between Date
84.1.2
Checking Dates . . . . . .
84.1.3
Typesetting Dates . . . .
84.1.4
Localization . . . . . . . .
84.2
Typesetting Calendars . . . . . . .
. . . .
Types
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906
906
906
907
908
909
909
Page
85.1
85.2
85.3
85.4
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912
912
913
915
918
85
Management
Basic Usage . . . . . .
The Predefined Layouts
Defining a Layout . . .
Creating Logical Pages
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901
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86
Extended Color Support
919
87
Parser Module
920
VIII
Mathematical and Object-Oriented Engines
921
88
Design Principles
88.1
Loading the Mathematical Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
88.2
Layers of the Mathematical Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
88.3
Efficiency and Accuracy of the Mathematical Engine . . . . . . . . . . . . . . . . . . .
922
922
922
922
89
Mathematical Expressions
89.1
Parsing Expressions . . . . . . . . . . . . . . . . .
89.1.1
Commands . . . . . . . . . . . . . . . .
89.1.2
Considerations Concerning Units . . . .
89.2
Syntax for Mathematical Expressions: Operators
89.3
Syntax for Mathematical Expressions: Functions .
89.3.1
Basic arithmetic functions . . . . . . . .
89.3.2
Rounding functions . . . . . . . . . . . .
89.3.3
Integer arithmetics functions . . . . . .
89.3.4
Trigonometric functions . . . . . . . . .
89.3.5
Comparison and logical functions . . . .
89.3.6
Pseudo-random functions . . . . . . . .
89.3.7
Base conversion functions . . . . . . . .
89.3.8
Miscellaneous functions . . . . . . . . .
923
923
923
925
926
928
928
930
931
932
934
935
936
937
19
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90
Additional Mathematical Commands
90.1
Basic arithmetic functions . . . . .
90.2
Comparison and logical functions .
90.3
Pseudo-Random Numbers . . . . .
90.4
Base Conversion . . . . . . . . . . .
90.5
Angle Computations . . . . . . . .
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939
939
939
939
940
941
91
Customizing the Mathematical Engine
942
92
Number Printing
92.1
Changing display styles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
945
950
93
Object-Oriented Programming
93.1
Overview . . . . . . . . . . . . . . . . .
93.2
A Running Example: The Stamp Class
93.3
Classes . . . . . . . . . . . . . . . . . .
93.4
Objects . . . . . . . . . . . . . . . . . .
93.5
Methods . . . . . . . . . . . . . . . . .
93.6
Attributes . . . . . . . . . . . . . . . .
93.7
Identities . . . . . . . . . . . . . . . . .
93.8
The Object Class . . . . . . . . . . . .
93.9
The Signal Class . . . . . . . . . . . . .
93.10 Implementation Notes . . . . . . . . . .
955
955
955
955
956
957
958
960
961
961
962
IX
94
95
96
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The Basic Layer
963
Design Principles
94.1
Core and Modules . . . . . . . . . . . . . . . . . .
94.2
Communicating with the Basic Layer via Macros
94.3
Path-Centered Approach . . . . . . . . . . . . . .
94.4
Coordinate Versus Canvas Transformations . . . .
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964
964
964
965
965
Hierarchical Structures: Package, Environments, Scopes, and
95.1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
95.1.1
The Hierarchical Structure of the Package . . . . . .
95.1.2
The Hierarchical Structure of Graphics . . . . . . . .
95.2
The Hierarchical Structure of the Package . . . . . . . . . . .
95.2.1
The Core Package . . . . . . . . . . . . . . . . . . .
95.2.2
The Modules . . . . . . . . . . . . . . . . . . . . . .
95.2.3
The Library Packages . . . . . . . . . . . . . . . . .
95.3
The Hierarchical Structure of the Graphics . . . . . . . . . . .
95.3.1
The Main Environment . . . . . . . . . . . . . . . .
95.3.2
Graphic Scope Environments . . . . . . . . . . . . .
95.3.3
Inserting Text and Images . . . . . . . . . . . . . . .
95.4
Error Messages and Warnings . . . . . . . . . . . . . . . . . .
Text
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966
966
966
966
967
967
968
968
968
968
970
973
975
Specifying Coordinates
96.1
Overview . . . . . . . . . . . . . . . . . . . . . . .
96.2
Basic Coordinate Commands . . . . . . . . . . . .
96.3
Coordinates in the XY-Coordinate System . . . .
96.4
Three Dimensional Coordinates . . . . . . . . . .
96.5
Building Coordinates From Other Coordinates . .
96.5.1
Basic Manipulations of Coordinates . . .
96.5.2
Points Traveling along Lines and Curves
96.5.3
Points on Borders of Objects . . . . . .
96.5.4
Points on the Intersection of Lines . . .
96.5.5
Points on the Intersection of Two Circles
96.5.6
Points on the Intersection of Two Paths
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976
976
976
976
977
978
978
979
980
981
981
982
20
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96.6
96.7
97
98
99
Extracting Coordinates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Internals of How Point Commands Work . . . . . . . . . . . . . . . . . . . . . . . . . .
983
983
Constructing Paths
97.1
Overview . . . . . . . . . . . . . . . . . . . . .
97.2
The Move-To Path Operation . . . . . . . . .
97.3
The Line-To Path Operation . . . . . . . . . .
97.4
The Curve-To Path Operations . . . . . . . .
97.5
The Close Path Operation . . . . . . . . . . .
97.6
Arc, Ellipse and Circle Path Operations . . . .
97.7
Rectangle Path Operations . . . . . . . . . . .
97.8
The Grid Path Operation . . . . . . . . . . . .
97.9
The Parabola Path Operation . . . . . . . . .
97.10 Sine and Cosine Path Operations . . . . . . .
97.11 Plot Path Operations . . . . . . . . . . . . . .
97.12 Rounded Corners . . . . . . . . . . . . . . . .
97.13 Internal Tracking of Bounding Boxes for Paths
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and Pictures
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985
985
985
986
986
987
988
991
991
992
992
993
993
994
Decorations
98.1
Overview . . . . . . . . . . . . . . . .
98.2
Decoration Automata . . . . . . . . .
98.2.1
The Different Paths . . . .
98.2.2
Segments and States . . . .
98.3
Declaring Decorations . . . . . . . . .
98.3.1
Predefined Decorations . . .
98.4
Using Decorations . . . . . . . . . . .
98.5
Meta-Decorations . . . . . . . . . . .
98.5.1
Declaring Meta-Decorations
98.5.2
Predefined Meta-decorations
98.5.3
Using Meta-Decorations . .
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996
996
996
996
997
998
1002
1002
1005
1006
1007
1007
Using Paths
99.1
Overview . . . . . . . . . . . . . . . . . . . . .
99.2
Stroking a Path . . . . . . . . . . . . . . . . .
99.2.1
Graphic Parameter: Line Width . .
99.2.2
Graphic Parameter: Caps and Joins
99.2.3
Graphic Parameter: Dashing . . . .
99.2.4
Graphic Parameter: Stroke Color . .
99.2.5
Graphic Parameter: Stroke Opacity
99.2.6
Inner Lines . . . . . . . . . . . . . .
99.3
Arrow Tips on a Path . . . . . . . . . . . . . .
99.4
Filling a Path . . . . . . . . . . . . . . . . . .
99.4.1
Graphic Parameter: Interior Rule . .
99.4.2
Graphic Parameter: Filling Color . .
99.4.3
Graphic Parameter: Fill Opacity . .
99.5
Clipping a Path . . . . . . . . . . . . . . . . .
99.6
Using a Path as a Bounding Box . . . . . . . .
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1009
1009
1010
1010
1010
1010
1011
1011
1011
1012
1013
1013
1014
1014
1014
1014
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1015
1015
1015
1016
1017
1021
1021
1022
1022
1023
100 Defining New Arrow Tip Kinds
100.1 Overview . . . . . . . . . . . . . . .
100.2 Terminology . . . . . . . . . . . . .
100.3 Caching and Rendering of Arrows .
100.4 Declaring an Arrow Tip Kind . . .
100.5 Handling Arrow Options . . . . . .
100.5.1 Dimension Options . . . .
100.5.2 True–False Options . . . .
100.5.3 Inaccessible Options . . .
100.5.4 Defining New Arrow Keys
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21
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101 Nodes and Shapes
101.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
101.1.1 Creating and Referencing Nodes . . . . . . . . . .
101.1.2 Anchors . . . . . . . . . . . . . . . . . . . . . . . .
101.1.3 Layers of a Shape . . . . . . . . . . . . . . . . . . .
101.1.4 Node Parts . . . . . . . . . . . . . . . . . . . . . .
101.2 Creating Nodes . . . . . . . . . . . . . . . . . . . . . . . . .
101.2.1 Creating Simple Nodes . . . . . . . . . . . . . . . .
101.2.2 Creating Multi-Part Nodes . . . . . . . . . . . . .
101.2.3 Deferred Node Positioning . . . . . . . . . . . . . .
101.3 Using Anchors . . . . . . . . . . . . . . . . . . . . . . . . . .
101.3.1 Referencing Anchors of Nodes in the Same Picture
101.3.2 Referencing Anchors of Nodes in Different Pictures
101.4 Special Nodes . . . . . . . . . . . . . . . . . . . . . . . . . .
101.5 Declaring New Shapes . . . . . . . . . . . . . . . . . . . . .
101.5.1 What Must Be Defined For a Shape? . . . . . . . .
101.5.2 Normal Anchors Versus Saved Anchors . . . . . . .
101.5.3 Command for Declaring New Shapes . . . . . . . .
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1025
1025
1025
1025
1025
1026
1026
1026
1027
1029
1030
1031
1032
1032
1033
1033
1034
1034
102 Matrices
102.1 Overview . . . . . . . . . . . . . . .
102.2 Cell Pictures and Their Alignment .
102.3 The Matrix Command . . . . . . .
102.4 Row and Column Spacing . . . . .
102.5 Callbacks . . . . . . . . . . . . . . .
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1040
1040
1040
1040
1042
1044
103 Coordinate, Canvas, and Nonlinear Transformations
103.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
103.2 Coordinate Transformations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
103.2.1 How PGF Keeps Track of the Coordinate Transformation Matrix . . . . .
103.2.2 Commands for Relative Coordinate Transformations . . . . . . . . . . . .
103.2.3 Commands for Absolute Coordinate Transformations . . . . . . . . . . . .
103.2.4 Saving and Restoring the Coordinate Transformation Matrix . . . . . . .
103.2.5 Computing Adjustments for Coordinate Transformations . . . . . . . . . .
103.3 Canvas Transformations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
103.4 Nonlinear Transformations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
103.4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
103.4.2 Installing Nonlinear Transformation . . . . . . . . . . . . . . . . . . . . .
103.4.3 Applying Nonlinear Transformations to Points . . . . . . . . . . . . . . .
103.4.4 Applying Nonlinear Transformations to Paths . . . . . . . . . . . . . . . .
103.4.5 Applying Nonlinear Transformations to Text . . . . . . . . . . . . . . . .
103.4.6 Approximating Nonlinear Transformations Using Linear Transformations
103.4.7 Nonlinear Transformation Libraries . . . . . . . . . . . . . . . . . . . . . .
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1045
1045
1045
1045
1046
1049
1050
1051
1051
1053
1053
1053
1054
1054
1055
1055
1056
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104 Patterns
1059
104.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1059
104.2 Declaring a Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1059
104.3 Setting a Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1061
105 Declaring and Using Images
105.1 Overview . . . . . . . . .
105.2 Declaring an Image . . .
105.3 Using an Image . . . . .
105.4 Masking an Image . . . .
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22
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1062
1062
1062
1063
1064
106 Externalizing Graphics
106.1 Overview . . . . . . . . . . . . . . . . . . . . . . . .
106.2 Workflow Step 1: Naming Graphics . . . . . . . . .
106.3 Workflow Step 2: Generating the External Graphics
106.4 Workflow Step 3: Including the External Graphics .
106.5 A Complete Example . . . . . . . . . . . . . . . . .
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1066
1066
1066
1067
1068
1069
107 Creating Plots
107.1 Overview . . . . . . . . . . . . . . . . . . . . . . .
107.2 Generating Plot Streams . . . . . . . . . . . . . .
107.2.1 Basic Building Blocks of Plot Streams .
107.2.2 Commands That Generate Plot Streams
107.3 Plot Handlers . . . . . . . . . . . . . . . . . . . .
107.4 Defining New Plot Handlers . . . . . . . . . . . .
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1073
1073
1073
1073
1075
1077
1078
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108 Layered Graphics
1080
108.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1080
108.2 Declaring Layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1080
108.3 Using Layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1080
109 Shadings
109.1 Overview . . . . . . . . . . . . . . . . . . .
109.2 Declaring Shadings . . . . . . . . . . . . .
109.2.1 Horizontal and Vertical Shadings
109.2.2 Radial Shadings . . . . . . . . . .
109.2.3 General (Functional) Shadings .
109.3 Using Shadings . . . . . . . . . . . . . . .
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1082
1082
1082
1082
1083
1083
1085
110 Transparency
110.1 Specifying a Uniform Opacity
110.2 Specifying a Blend Mode . . .
110.3 Specifying a Fading . . . . . .
110.4 Transparency Groups . . . . .
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1089
1089
1089
1090
1092
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111 Adding libraries to pgf: temporary registers
112 Quick
112.1
112.2
112.3
112.4
X
Commands
Quick Coordinate Commands . . . .
Quick Path Construction Commands
Quick Path Usage Commands . . . .
Quick Text Box Commands . . . . .
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1094
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The System Layer
1096
1096
1096
1097
1097
1099
113 Design of the System Layer
1100
113.1 Driver Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1100
113.2 Common Definition Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1100
114 Commands of the System Layer
114.1 Beginning and Ending a Stream of System Commands
114.2 Path Construction System Commands . . . . . . . . .
114.3 Canvas Transformation System Commands . . . . . . .
114.4 Stroking, Filling, and Clipping System Commands . . .
114.5 Graphic State Option System Commands . . . . . . . .
114.6 Color System Commands . . . . . . . . . . . . . . . . .
114.7 Pattern System Commands . . . . . . . . . . . . . . . .
114.8 Scoping System Commands . . . . . . . . . . . . . . .
114.9 Image System Commands . . . . . . . . . . . . . . . .
114.10 Shading System Commands . . . . . . . . . . . . . . .
23
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1101
1101
1102
1103
1103
1104
1105
1107
1107
1108
1108
114.11
114.12
114.13
114.14
114.15
114.16
Transparency System Commands . .
Reusable Objects System Commands
Invisibility System Commands . . . .
Page Size Commands . . . . . . . . .
Position Tracking Commands . . . .
Internal Conversion Commands . . .
115 The Soft Path Subsystem
115.1 Path Creation Process . . . . .
115.2 Starting and Ending a Soft Path
115.3 Soft Path Creation Commands .
115.4 The Soft Path Data Structure .
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1109
1110
1110
1111
1111
1112
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1113
1113
1113
1114
1114
116 The Protocol Subsystem
XI
1116
References and Index
1117
Index
1118
24
1
Introduction
Welcome to the documentation of Tik Z and the underlying pgf system. What began as a small LaTEX style
for creating the graphics in my (Till Tantau’s) PhD thesis directly with pdfLATEX has now grown to become
a full-flung graphics language with a manual of over a thousand pages. The wealth of options offered by
Tik Z is often daunting to beginners; but fortunately this documentation comes with a number slowly-paced
tutorials that will teach you almost all you should know about Tik Z without your having to read the rest.
I wish to start with the questions “What is Tik Z?” Basically, it just defines a number of TEX commands
that draw graphics. For example, the code \tikz \draw (0pt,0pt) --(20pt,6pt); yields the line
and the code \tikz \fill[orange] (1ex,1ex) circle (1ex); yields . In a sense, when you use Tik Z
you “program” your graphics, just as you “program” your document when you use TEX. This also explains
the name: Tik Z is a recursive accronym in the tradition of “gnu is not unix” and means “Tik Z ist kein
Zeichenprogramm,” which translates to “Tik Z is not a drawing program,” cautioning the reader as to what
to expect. With Tik Z you get all the advantages of the “TEX-approach to typesetting” for your graphics:
quick creation of simple graphics, precise positioning, the use of macros, often superior typography. You also
inherit all the disadvantages: steep learning curve, no wysiwyg, small changes require a long recompilation
time, and the code does not really “show” how things will look like.
Now that we know what Tik Z is, what about “pgf”? As mentioned earlier, Tik Z started out as a
project to implement TEX graphics macros that can be used both with pdfLATEX and also with the classical
(PostScript-based) LATEX. In other words, I wanted to implement a “portable graphics format” for TEX –
hence the name pgf. These early macros are still around and they form the “basic layer” of the system
described in this manual, but most of the interaction an author has theses days is with Tik Z – which has
become a whole language of its own.
1.1
The Layers Below Tik Z
It turns out that there are actually two layers below Tik Z:
System layer: This layer provides a complete abstraction of what is going on “in the driver.” The driver
is a program like dvips or dvipdfm that takes a .dvi file as input and generates a .ps or a .pdf file.
(The pdftex program also counts as a driver, even though it does not take a .dvi file as input. Never
mind.) Each driver has its own syntax for the generation of graphics, causing headaches to everyone
who wants to create graphics in a portable way. pgf’s system layer “abstracts away” these differences.
For example, the system command \pgfsys@lineto{10pt}{10pt} extends the current path to the
coordinate (10pt, 10pt) of the current {pgfpicture}. Depending on whether dvips, dvipdfm, or
pdftex is used to process the document, the system command will be converted to different \special
commands. The system layer is as “minimalistic” as possible since each additional command makes it
more work to port pgf to a new driver.
As a user, you will not use the system layer directly.
Basic layer: The basic layer provides a set of basic commands that allow you to produce complex graphics
in a much easier manner than by using the system layer directly. For example, the system layer provides
no commands for creating circles since circles can be composed from the more basic Bézier curves (well,
almost). However, as a user you will want to have a simple command to create circles (at least I do)
instead of having to write down half a page of Bézier curve support coordinates. Thus, the basic layer
provides a command \pgfpathcircle that generates the necessary curve coordinates for you.
The basic layer consists of a core, which consists of several interdependent packages that can only be
loaded en bloc, and additional modules that extend the core by more special-purpose commands like
node management or a plotting interface. For instance, the beamer package uses only the core and
not, say, the shapes modules.
In theory, Tik Zitself is just one of several possible “frontends,” which are sets of commands or a special
syntax that makes using the basic layer easier. A problem with directly using the basic layer is that code
written for this layer is often too “verbose.” For example, to draw a simple triangle, you may need as many
as five commands when using the basic layer: One for beginning a path at the first corner of the triangle,
one for extending the path to the second corner, one for going to the third, one for closing the path, and one
for actually painting the triangle (as opposed to filling it). With the Tik Z frontend all this boils down to a
single simple metafont-like command:
\draw (0,0) -- (1,0) -- (1,1) -- cycle;
25
In practice, Tik Z is the only “serious” frontend for pgf. It gives you access to all features of pgf, but
it is intended to be easy to use. The syntax is a mixture of metafont and pstricks and some ideas of
myself. There are other frontends besides Tik Z, but they are more intended as “technology studies” and
less as serious alternatives to Tik Z. In particular, the pgfpict2e frontend reimplements the standard LATEX
{picture} environment and commands like \line or \vector using the pgf basic layer. This layer is not
really “necessary” since the pict2e.sty package does at least as good a job at reimplementing the {picture}
environment. Rather, the idea behind this package is to have a simple demonstration of how a frontend can
be implemented.
Since most users will only use Tik Z and almost no one will use the system layer directly, this manual is
mainly about Tik Z in the first parts; the basic layer and the system layer are explained at the end.
1.2
Comparison with Other Graphics Packages
Tik Z is not the only graphics package for TEX. In the following, I try to give a reasonably fair comparison
of Tik Z and other packages.
1. The standard LATEX {picture} environment allows you to create simple graphics, but little more. This
is certainly not due to a lack of knowledge or imagination on the part of LATEX’s designer(s). Rather,
this is the price paid for the {picture} environment’s portability: It works together with all backend
drivers.
2. The pstricks package is certainly powerful enough to create any conceivable kind of graphic, but it
is not really portable. Most importantly, it does not work with pdftex nor with any other driver that
produces anything but PostScript code.
Compared to Tik Z, pstricks has a similar support base. There are many nice extra packages for
special purpose situations that have been contributed by users over the last decade. The Tik Z syntax
is more consistent than the pstricks syntax as Tik Z was developed “in a more centralized manner”
and also “with the shortcomings on pstricks in mind.”
3. The xypic package is an older package for creating graphics. However, it is more difficult to use and
to learn because the syntax and the documentation are a bit cryptic.
4. The dratex package is a small graphic package for creating a graphics. Compared to the other package,
including Tik Z, it is very small, which may or may not be an advantage.
5. The metapost program is a powerful alternative to Tik Z. It used to be an external program, which
entailed a bunch of problems, but in LuaTEX it is now build in. An obstacle with metapost is the
inclusion of labels. This is much easier to achieve using pgf.
6. The xfig program is an important alternative to Tik Z for users who do not wish to “program” their
graphics as is necessary with Tik Z and the other packages above. There is a conversion program that
will convert xfig graphics to Tik Z.
1.3
Utility Packages
The pgf package comes along with a number of utility package that are not really about creating graphics
and which can be used independently of pgf. However, they are bundled with pgf, partly out of convenience,
partly because their functionality is closely intertwined with pgf. These utility packages are:
1. The pgfkeys package defines a powerful key management facility. It can be used completely independently of pgf.
2. The pgffor package defines a useful \foreach statement.
3. The pgfcalendar package defines macros for creating calendars. Typically, these calendars will be
rendered using pgf’s graphic engine, but you can use pgfcalendar also typeset calendars using normal
text. The package also defines commands for “working” with dates.
4. The pgfpages package is used to assemble several pages into a single page. It provides commands for
assembling several “virtual pages” into a single “physical page.” The idea is that whenever TEX has a
page ready for “shipout,” pgfpages interrupts this shipout and instead stores the page to be shipped
out in a special box. When enough “virtual pages” have been accumulated in this way, they are scaled
26
down and arranged on a “physical page,” which then really shipped out. This mechanism allows you
to create “two page on one page” versions of a document directly inside LATEX without the use of any
external programs. However, pgfpages can do quite a lot more than that. You can use it to put logos
and watermark on pages, print up to 16 pages on one page, add borders to pages, and more.
1.4
How to Read This Manual
This manual describes both the design of Tik Z and its usage. The organization is very roughly according to
“user-friendliness.” The commands and subpackages that are easiest and most frequently used are described
first, more low-level and esoteric features are discussed later.
If you have not yet installed Tik Z, please read the installation first. Second, it might be a good idea to
read the tutorial. Finally, you might wish to skim through the description of Tik Z. Typically, you will not
need to read the sections on the basic layer. You will only need to read the part on the system layer if you
intend to write your own frontend or if you wish to port pgf to a new driver.
The “public” commands and environments provided by the system are described throughout the text. In
each such description, the described command, environment or option is printed in red. Text shown in green
is optional and can be left out.
1.5
Authors and Acknowledgements
The bulk of the pgf system and its documentation was written by Till Tantau. A further member of the main
team is Mark Wibrow, who is responsible, for example, for the pgf mathematical engine, many shapes, the
decoration engine, and matrices. The third member is Christian Feuersänger who contributed the floating
point library, image externalization, extended key processing, and automatic hyperlinks in the manual.
Furthermore, occasional contributions have been made by Christophe Jorssen, Jin-Hwan Cho, Olivier
Binda, Matthias Schulz, Renée Ahrens, Stephan Schuster, and Thomas Neumann.
Additionally, numerous people have contributed to the pgf system by writing emails, spotting bugs, or
sending libraries and patches. Many thanks to all these people, who are too numerous to name them all!
1.6
Getting Help
When you need help with pgf and Tik Z, please do the following:
1. Read the manual, at least the part that has to do with your problem.
2. If that does not solve the problem, try having a look at the sourceforge development page for pgf and
Tik Z (see the title of this document). Perhaps someone has already reported a similar problem and
someone has found a solution.
3. On the website you will find numerous forums for getting help. There, you can write to help forums,
file bug reports, join mailing lists, and so on.
4. Before you file a bug report, especially a bug report concerning the installation, make sure that this is
really a bug. In particular, have a look at the .log file that results when you TEX your files. This .log
file should show that all the right files are loaded from the right directories. Nearly all installation
problems can be resolved by looking at the .log file.
5. As a last resort you can try to email me (Till Tantau) or, if the problem concerns the mathematical
engine, Mark Wibrow. I do not mind getting emails, I simply get way too many of them. Because of
this, I cannot guarantee that your emails will be answered timely or even at all. Your chances that
your problem will be fixed are somewhat higher if you mail to the pgf mailing list (naturally, I read
this list and answer questions when I have the time).
27
Part I
Tutorials and Guidelines
by Till Tantau
To help you get started with Tik Z, instead of a long installation and configuration section, this manual starts
with tutorials. They explain all the basic and some of the more advanced features of the system, without
going into all the details. This part also contains some guidelines on how you should proceed when creating
graphics using Tik Z.
\tikz \draw[thick,rounded corners=8pt]
(0,0) -- (0,2) -- (1,3.25) -- (2,2) -- (2,0) -- (0,2) -- (2,2) -- (0,0) -- (2,0);
28
2
Tutorial: A Picture for Karl’s Students
This tutorial is intended for new users of Tik Z. It does not give an exhaustive account of all the features of
Tik Z, just of those that you are likely to use right away.
Karl is a math and chemistry high-school teacher. He used to create the graphics in his worksheets and
exams using LATEX’s {picture} environment. While the results were acceptable, creating the graphics often
turned out to be a lengthy process. Also, there tended to be problems with lines having slightly wrong angles
and circles also seemed to be hard to get right. Naturally, his students could not care less whether the lines
had the exact right angles and they find Karl’s exams too difficult no matter how nicely they were drawn.
But Karl was never entirely satisfied with the result.
Karl’s son, who was even less satisfied with the results (he did not have to take the exams, after all),
told Karl that he might wish to try out a new package for creating graphics. A bit confusingly, this package
seems to have two names: First, Karl had to download and install a package called pgf. Then it turns out
that inside this package there is another package called Tik Z, which is supposed to stand for “Tik Z ist kein
Zeichenprogramm.” Karl finds this all a bit strange and Tik Z seems to indicate that the package does not
do what he needs. However, having used gnu software for quite some time and “gnu not being Unix,” there
seems to be hope yet. His son assures him that Tik Z’s name is intended to warn people that Tik Z is not a
program that you can use to draw graphics with your mouse or tablet. Rather, it is more like a “graphics
language.”
2.1
Problem Statement
Karl wants to put a graphic on the next worksheet for his students. He is currently teaching his students
about sine and cosine. What he would like to have is something that looks like this (ideally):
y
The angle α is 30◦ in the example
(π/6 in radians). The sine of α, which
is the height of the red line, is
1
sin α = 1/2.
1
2
tan α =
sin α
α
−1
cos α
− 12
x
1
− 12
By the Theorem of Pythagoras we
have cos2 α + sin2 α = 1. Thus the
length of the blue line, which is the
cosine of α, must be
p
√
cos α = 1 − 1/4 = 12 3.
This shows that tan α, which is the
height of the orange line, is
−1
2.2
sin α
cos α
tan α =
√
sin α
= 1/ 3.
cos α
Setting up the Environment
In Tik Z, to draw a picture, at the start of the picture you need to tell TEX or LATEX that you want to
start a picture. In LATEX this is done using the environment {tikzpicture}, in plain TEX you just use
\tikzpicture to start the picture and \endtikzpicture to end it.
2.2.1
Setting up the Environment in LATEX
Karl, being a LATEX user, thus sets up his file as follows:
29
\documentclass{article} % say
\usepackage{tikz}
\begin{document}
We are working on
\begin{tikzpicture}
\draw (-1.5,0) -- (1.5,0);
\draw (0,-1.5) -- (0,1.5);
\end{tikzpicture}.
\end{document}
When executed, that is, run via pdflatex or via latex followed by dvips, the resulting will contain
something that looks like this:
We are working on
\begin{tikzpicture}
\draw (-1.5,0) -- (1.5,0);
\draw (0,-1.5) -- (0,1.5);
\end{tikzpicture}.
We are working on
.
Admittedly, not quite the whole picture, yet, but we do have the axes established. Well, not quite, but
we have the lines that make up the axes drawn. Karl suddenly has a sinking feeling that the picture is still
some way off.
Let’s have a more detailed look at the code. First, the package tikz is loaded. This package is a so-called
“frontend” to the basic pgf system. The basic layer, which is also described in this manual, is somewhat
more, well, basic and thus harder to use. The frontend makes things easier by providing a simpler syntax.
Inside the environment there are two \draw commands. They mean: “The path, which is specified
following the command up to the semicolon, should be drawn.” The first path is specified as (-1.5,0)
--(0,1.5), which means “a straight line from the point at position (−1.5, 0) to the point at position (0, 1.5).”
Here, the positions are specified within a special coordinate system in which, initially, one unit is 1cm.
Karl is quite pleased to note that the environment automatically reserves enough space to encompass the
picture.
2.2.2
Setting up the Environment in Plain TEX
Karl’s wife Gerda, who also happens to be a math teacher, is not a LATEX user, but uses plain TEX since
she prefers to do things “the old way.” She can also use Tik Z. Instead of \usepackage{tikz} she has
to write \input tikz.tex and instead of \begin{tikzpicture} she writes \tikzpicture and instead of
\end{tikzpicture} she writes \endtikzpicture.
Thus, she would use:
%% Plain TeX file
\input tikz.tex
\baselineskip=12pt
\hsize=6.3truein
\vsize=8.7truein
We are working on
\tikzpicture
\draw (-1.5,0) -- (1.5,0);
\draw (0,-1.5) -- (0,1.5);
\endtikzpicture.
\bye
Gerda can typeset this file using either pdftex or tex together with dvips. Tik Z will automatically
discern which driver she is using. If she wishes to use dvipdfm together with tex, she either needs to
modify the file pgf.cfg or can write \def\pgfsysdriver{pgfsys-dvipdfm.def} somewhere before she
inputs tikz.tex or pgf.tex.
2.2.3
Setting up the Environment in ConTEXt
Karl’s uncle Hans uses ConTEXt. Like Gerda, Hans can also use Tik Z. Instead of \usepackage{tikz} he
says \usemodule[tikz]. Instead of \begin{tikzpicture} he writes \starttikzpicture and instead of
\end{tikzpicture} he writes \stoptikzpicture.
30
His version of the example looks like this:
%% ConTeXt file
\usemodule[tikz]
\starttext
We are working on
\starttikzpicture
\draw (-1.5,0) -- (1.5,0);
\draw (0,-1.5) -- (0,1.5);
\stoptikzpicture.
\stoptext
Hans will now typeset this file in the usual way using texexec or context.
2.3
Straight Path Construction
The basic building block of all pictures in Tik Z is the path. A path is a series of straight lines and curves
that are connected (that is not the whole picture, but let us ignore the complications for the moment). You
start a path by specifying the coordinates of the start position as a point in round brackets, as in (0,0).
This is followed by a series of “path extension operations.” The simplest is --, which we used already. It
must be followed by another coordinate and it extends the path in a straight line to this new position. For
example, if we were to turn the two paths of the axes into one path, the following would result:
\tikz \draw (-1.5,0) -- (1.5,0) -- (0,-1.5) -- (0,1.5);
Karl is a bit confused by the fact that there is no {tikzpicture} environment, here. Instead, the little
command \tikz is used. This command either takes one argument (starting with an opening brace as in
\tikz{\draw (0,0) --(1.5,0)}, which yields
) or collects everything up to the next semicolon
and puts it inside a {tikzpicture} environment. As a rule of thumb, all Tik Z graphic drawing commands
must occur as an argument of \tikz or inside a {tikzpicture} environment. Fortunately, the command
\draw will only be defined inside this environment, so there is little chance that you will accidentally do
something wrong here.
2.4
Curved Path Construction
The next thing Karl wants to do is to draw the circle. For this, straight lines obviously will not do. Instead,
we need some way to draw curves. For this, Tik Z provides a special syntax. One or two “control points”
are needed. The math behind them is not quite trivial, but here is the basic idea: Suppose you are at point
x and the first control point is y. Then the curve will start “going in the direction of y at x,” that is, the
tangent of the curve at x will point toward y. Next, suppose the curve should end at z and the second
support point is w. Then the curve will, indeed, end at z and the tangent of the curve at point z will go
through w.
Here is an example (the control points have been added for clarity):
\begin{tikzpicture}
\filldraw [gray] (0,0) circle
(1,1) circle
(2,1) circle
(2,0) circle
\draw (0,0) .. controls (1,1)
\end{tikzpicture}
[radius=2pt]
[radius=2pt]
[radius=2pt]
[radius=2pt];
and (2,1) .. (2,0);
The general syntax for extending a path in a “curved” way is .. controls hfirst control pointi and
hsecond control pointi .. hend pointi. You can leave out the and hsecond control pointi, which causes the
first one to be used twice.
So, Karl can now add the first half circle to the picture:
31
\begin{tikzpicture}
\draw (-1.5,0) -- (1.5,0);
\draw (0,-1.5) -- (0,1.5);
\draw (-1,0) .. controls (-1,0.555) and (-0.555,1) .. (0,1)
.. controls (0.555,1) and (1,0.555) .. (1,0);
\end{tikzpicture}
Karl is happy with the result, but finds specifying circles in this way to be extremely awkward. Fortunately, there is a much simpler way.
2.5
Circle Path Construction
In order to draw a circle, the path construction operation circle can be used. This operation is followed
by a radius in brackets as in the following example: (Note that the previous position is used as the center
of the circle.)
\tikz \draw (0,0) circle [radius=10pt];
You can also append an ellipse to the path using the ellipse operation. Instead of a single radius you
can specify two of them:
\tikz \draw (0,0) ellipse [x radius=20pt, y radius=10pt];
To draw an ellipse whose axes are not horizontal and vertical, but point in an arbitrary direction (a
“turned ellipse” like
) you can use transformations, which are explained later. The code for the little
ellipse is \tikz \draw[rotate=30] (0,0) ellipse [x radius=6pt, y radius=3pt];, by the way.
So, returning to Karl’s problem, he can write \draw (0,0) circle [radius=1cm]; to draw the circle:
\begin{tikzpicture}
\draw (-1.5,0) -- (1.5,0);
\draw (0,-1.5) -- (0,1.5);
\draw (0,0) circle [radius=1cm];
\end{tikzpicture}
At this point, Karl is a bit alarmed that the circle is so small when he wants the final picture to be much
bigger. He is pleased to learn that Tik Z has powerful transformation options and scaling everything by a
factor of three is very easy. But let us leave the size as it is for the moment to save some space.
2.6
Rectangle Path Construction
The next things we would like to have is the grid in the background. There are several ways to produce it.
For example, one might draw lots of rectangles. Since rectangles are so common, there is a special syntax
for them: To add a rectangle to the current path, use the rectangle path construction operation. This
operation should be followed by another coordinate and will append a rectangle to the path such that the
previous coordinate and the next coordinates are corners of the rectangle. So, let us add two rectangles to
the picture:
\begin{tikzpicture}
\draw (-1.5,0) -- (1.5,0);
\draw (0,-1.5) -- (0,1.5);
\draw (0,0) circle [radius=1cm];
\draw (0,0) rectangle (0.5,0.5);
\draw (-0.5,-0.5) rectangle (-1,-1);
\end{tikzpicture}
32
While this may be nice in other situations, this is not really leading anywhere with Karl’s problem: First,
we would need an awful lot of these rectangles and then there is the border that is not “closed.”
So, Karl is about to resort to simply drawing four vertical and four horizontal lines using the nice \draw
command, when he learns that there is a grid path construction operation.
2.7
Grid Path Construction
The grid path operation adds a grid to the current path. It will add lines making up a grid that fills
the rectangle whose one corner is the current point and whose other corner is the point following the grid
operation. For example, the code \tikz \draw[step=2pt] (0,0) grid (10pt,10pt); produces . Note
how the optional argument for \draw can be used to specify a grid width (there are also xstep and ystep to
define the steppings independently). As Karl will learn soon, there are lots of things that can be influenced
using such options.
For Karl, the following code could be used:
\begin{tikzpicture}
\draw (-1.5,0) -- (1.5,0);
\draw (0,-1.5) -- (0,1.5);
\draw (0,0) circle [radius=1cm];
\draw[step=.5cm] (-1.4,-1.4) grid (1.4,1.4);
\end{tikzpicture}
Having another look at the desired picture, Karl notices that it would be nice for the grid to be more
subdued. (His son told him that grids tend to be distracting if they are not subdued.) To subdue the grid,
Karl adds two more options to the \draw command that draws the grid. First, he uses the color gray for the
grid lines. Second, he reduces the line width to very thin. Finally, he swaps the ordering of the commands
so that the grid is drawn first and everything else on top.
\begin{tikzpicture}
\draw[step=.5cm,gray,very thin] (-1.4,-1.4) grid (1.4,1.4);
\draw (-1.5,0) -- (1.5,0);
\draw (0,-1.5) -- (0,1.5);
\draw (0,0) circle [radius=1cm];
\end{tikzpicture}
2.8
Adding a Touch of Style
Instead of the options gray,very thin Karl could also have said help lines. Styles are predefined sets
of options that can be used to organize how a graphic is drawn. By saying help lines you say “use the
style that I (or someone else) has set for drawing help lines.” If Karl decides, at some later point, that
grids should be drawn, say, using the color blue!50 instead of gray, he could provide the following option
somewhere:
help lines/.style={color=blue!50,very thin}
The effect of this “style setter” is that in the current scope or environment the help lines option has
the same effect as color=blue!50,very thin.
Using styles makes your graphics code more flexible. You can change the way things look easily in a
consistent manner. Normally, styles are defined at the beginning of a picture. However, you may sometimes
wish to define a style globally, so that all pictures of your document can use this style. Then you can easily
change the way all graphics look by changing this one style. In this situation you can use the \tikzset
command at the beginning of the document as in
\tikzset{help lines/.style=very thin}
To build a hierarchy of styles you can have one style use another. So in order to define a style Karl’s
grid that is based on the grid style Karl could say
33
\tikzset{Karl’s grid/.style={help lines,color=blue!50}}
...
\draw[Karl’s grid] (0,0) grid (5,5);
Styles are made even more powerful by parametrization. This means that, like other options, styles can
also be used with a parameter. For instance, Karl could parameterize his grid so that, by default, it is blue,
but he could also use another color.
\begin{tikzpicture}
[Karl’s grid/.style ={help lines,color=#1!50},
Karl’s grid/.default=blue]
\draw[Karl’s grid]
(0,0) grid (1.5,2);
\draw[Karl’s grid=red] (2,0) grid (3.5,2);
\end{tikzpicture}
2.9
Drawing Options
Karl wonders what other options there are that influence how a path is drawn. He saw already that the
color=hcolor i option can be used to set the line’s color. The option draw=hcolor i does nearly the same, only
it sets the color for the lines only and a different color can be used for filling (Karl will need this when he
fills the arc for the angle).
He saw that the style very thin yields very thin lines. Karl is not really surprised by this and neither is
he surprised to learn that thin yields thin lines, thick yields thick lines, very thick yields very thick lines,
ultra thick yields really, really thick lines and ultra thin yields lines that are so thin that low-resolution
printers and displays will have trouble showing them. He wonders what gives lines of “normal” thickness.
It turns out that thin is the correct choice, since it gives the same thickness as TEX’s \hrule command.
Nevertheless, Karl would like to know whether there is anything “in the middle” between thin and thick.
There is: semithick.
Another useful thing one can do with lines is to dash or dot them. For this, the two styles dashed and
dotted can be used, yielding
and
. Both options also exist in a loose and a dense version, called
loosely dashed, densely dashed, loosely dotted, and densely dotted. If he really, really needs to,
Karl can also define much more complex dashing patterns with the dash pattern option, but his son insists
that dashing is to be used with utmost care and mostly distracts. Karl’s son claims that complicated dashing
patterns are evil. Karl’s students do not care about dashing patterns.
2.10
Arc Path Construction
Our next obstacle is to draw the arc for the angle. For this, the arc path construction operation is useful,
which draws part of a circle or ellipse. This arc operation is followed by options in brackets that specify
the arc. An example would be arc[start angle=10, end angle=80, radius=10pt], which means exactly
what it says. Karl obviously needs an arc from 0◦ to 30◦ . The radius should be something relatively small,
perhaps around one third of the circle’s radius. When one uses the arc path construction operation, the
specified arc will be added with its starting point at the current position. So, we first have to “get there.”
\begin{tikzpicture}
\draw[step=.5cm,gray,very thin] (-1.4,-1.4) grid (1.4,1.4);
\draw (-1.5,0) -- (1.5,0);
\draw (0,-1.5) -- (0,1.5);
\draw (0,0) circle [radius=1cm];
\draw (3mm,0mm) arc [start angle=0, end angle=30, radius=3mm];
\end{tikzpicture}
Karl thinks this is really a bit small and he cannot continue unless he learns how to do scaling. For this,
he can add the [scale=3] option. He could add this option to each \draw command, but that would be
awkward. Instead, he adds it to the whole environment, which causes this option to apply to everything
within.
34
\begin{tikzpicture}[scale=3]
\draw[step=.5cm,gray,very thin] (-1.4,-1.4) grid (1.4,1.4);
\draw (-1.5,0) -- (1.5,0);
\draw (0,-1.5) -- (0,1.5);
\draw (0,0) circle [radius=1cm];
\draw (3mm,0mm) arc [start angle=0, end angle=30, radius=3mm];
\end{tikzpicture}
As for circles, you can specify “two” radii in order to get an elliptical arc.
\tikz \draw (0,0)
arc [start angle=0, end angle=315,
x radius=1.75cm, y radius=1cm];
2.11
Clipping a Path
In order to save space in this manual, it would be nice to clip Karl’s graphics a bit so that we can focus
on the “interesting” parts. Clipping is pretty easy in Tik Z. You can use the \clip command to clip all
subsequent drawing. It works like \draw, only it does not draw anything, but uses the given path to clip
everything subsequently.
\begin{tikzpicture}[scale=3]
\clip (-0.1,-0.2) rectangle (1.1,0.75);
\draw[step=.5cm,gray,very thin] (-1.4,-1.4) grid (1.4,1.4);
\draw (-1.5,0) -- (1.5,0);
\draw (0,-1.5) -- (0,1.5);
\draw (0,0) circle [radius=1cm];
\draw (3mm,0mm) arc [start angle=0, end angle=30, radius=3mm];
\end{tikzpicture}
You can also do both at the same time: Draw and clip a path. For this, use the \draw command and
add the clip option. (This is not the whole picture: You can also use the \clip command and add the
draw option. Well, that is also not the whole picture: In reality, \draw is just a shorthand for \path[draw]
and \clip is a shorthand for \path[clip] and you could also say \path[draw,clip].) Here is an example:
35
\begin{tikzpicture}[scale=3]
\clip[draw] (0.5,0.5) circle (.6cm);
\draw[step=.5cm,gray,very thin] (-1.4,-1.4) grid (1.4,1.4);
\draw (-1.5,0) -- (1.5,0);
\draw (0,-1.5) -- (0,1.5);
\draw (0,0) circle [radius=1cm];
\draw (3mm,0mm) arc [start angle=0, end angle=30, radius=3mm];
\end{tikzpicture}
2.12
Parabola and Sine Path Construction
Although Karl does not need them for his picture, he is pleased to learn that there are parabola and sin and
cos path operations for adding parabolas and sine and cosine curves to the current path. For the parabola
operation, the current point will lie on the parabola as well as the point given after the parabola operation.
Consider the following example:
\tikz \draw (0,0) rectangle (1,1)
(0,0) parabola (1,1);
It is also possible to place the bend somewhere else:
\tikz \draw[x=1pt,y=1pt] (0,0) parabola bend (4,16) (6,12);
The operations sin and cos add a sine or cosine curve in the interval [0, π/2] such that the previous
current point is at the start of the curve and the curve ends at the given end point. Here are two examples:
A sine
curve.
A sine \tikz \draw[x=1ex,y=1ex] (0,0) sin (1.57,1); curve.
\tikz \draw[x=1.57ex,y=1ex] (0,0) sin (1,1) cos (2,0) sin (3,-1) cos (4,0)
(0,1) cos (1,0) sin (2,-1) cos (3,0) sin (4,1);
2.13
Filling and Drawing
Returning to the picture, Karl now wants the angle to be “filled” with a very light green. For this he uses
\fill instead of \draw. Here is what Karl does:
\begin{tikzpicture}[scale=3]
\clip (-0.1,-0.2) rectangle (1.1,0.75);
\draw[step=.5cm,gray,very thin] (-1.4,-1.4) grid (1.4,1.4);
\draw (-1.5,0) -- (1.5,0);
\draw (0,-1.5) -- (0,1.5);
\draw (0,0) circle [radius=1cm];
\fill[green!20!white] (0,0) -- (3mm,0mm)
arc [start angle=0, end angle=30, radius=3mm] -- (0,0);
\end{tikzpicture}
The color green!20!white means 20% green and 80% white mixed together. Such color expression are
possible since Tik Z uses Uwe Kern’s xcolor package, see the documentation of that package for details on
color expressions.
What would have happened, if Karl had not “closed” the path using --(0,0) at the end? In this case,
the path is closed automatically, so this could have been omitted. Indeed, it would even have been better to
write the following, instead:
\fill[green!20!white] (0,0) -- (3mm,0mm)
arc [start angle=0, end angle=30, radius=3mm] -- cycle;
The --cycle causes the current path to be closed (actually the current part of the current path) by
smoothly joining the first and last point. To appreciate the difference, consider the following example:
36
\begin{tikzpicture}[line width=5pt]
\draw (0,0) -- (1,0) -- (1,1) -- (0,0);
\draw (2,0) -- (3,0) -- (3,1) -- cycle;
\useasboundingbox (0,1.5); % make bounding box higher
\end{tikzpicture}
You can also fill and draw a path at the same time using the \filldraw command. This will first draw
the path, then fill it. This may not seem too useful, but you can specify different colors to be used for filling
and for stroking. These are specified as optional arguments like this:
\begin{tikzpicture}[scale=3]
\clip (-0.1,-0.2) rectangle (1.1,0.75);
\draw[step=.5cm,gray,very thin] (-1.4,-1.4) grid (1.4,1.4);
\draw (-1.5,0) -- (1.5,0);
\draw (0,-1.5) -- (0,1.5);
\draw (0,0) circle [radius=1cm];
\filldraw[fill=green!20!white, draw=green!50!black] (0,0) -- (3mm,0mm)
arc [start angle=0, end angle=30, radius=3mm] -- cycle;
\end{tikzpicture}
2.14
Shading
Karl briefly considers the possibility of making the angle “more fancy” by shading it. Instead of filling
the area with a uniform color, a smooth transition between different colors is used. For this, \shade and
\shadedraw, for shading and drawing at the same time, can be used:
\tikz \shade (0,0) rectangle (2,1)
(3,0.5) circle (.5cm);
The default shading is a smooth transition from gray to white. To specify different colors, you can use
options:
\begin{tikzpicture}[rounded corners,ultra thick]
\shade[top color=yellow,bottom color=black] (0,0) rectangle +(2,1);
\shade[left color=yellow,right color=black] (3,0) rectangle +(2,1);
\shadedraw[inner color=yellow,outer color=black,draw=yellow] (6,0) rectangle +(2,1);
\shade[ball color=green] (9,.5) circle (.5cm);
\end{tikzpicture}
For Karl, the following might be appropriate:
\begin{tikzpicture}[scale=3]
\clip (-0.1,-0.2) rectangle (1.1,0.75);
\draw[step=.5cm,gray,very thin] (-1.4,-1.4) grid (1.4,1.4);
\draw (-1.5,0) -- (1.5,0);
\draw (0,-1.5) -- (0,1.5);
\draw (0,0) circle [radius=1cm];
\shadedraw[left color=gray,right color=green, draw=green!50!black]
(0,0) -- (3mm,0mm)
arc [start angle=0, end angle=30, radius=3mm] -- cycle;
\end{tikzpicture}
However, he wisely decides that shadings usually only distract without adding anything to the picture.
2.15
Specifying Coordinates
Karl now wants to add the sine and cosine lines. He knows already that he can use the color= option to set
the lines’ colors. So, what is the best way to specify the coordinates?
There are different ways of specifying coordinates. The easiest way is to say something like (10pt,2cm).
This means 10pt in x-direction and 2cm in y-directions. Alternatively, you can also leave out the units as in
(1,2), which means “one times the current x-vector plus twice the current y-vector.” These vectors default
to 1cm in the x-direction and 1cm in the y-direction, respectively.
37
In order to specify points in polar coordinates, use the notation (30:1cm), which means 1cm in direction
30 degree. This is obviously quite useful to “get to the point (cos 30◦ , sin 30◦ ) on the circle.”
You can add a single + sign in front of a coordinate or two of them as in +(0cm,1cm) or ++(2cm,0cm).
Such coordinates are interpreted differently: The first form means “1cm upwards from the previous specified
position” and the second means “2cm to the right of the previous specified position, making this the new
specified position.” For example, we can draw the sine line as follows:
\begin{tikzpicture}[scale=3]
\clip (-0.1,-0.2) rectangle (1.1,0.75);
\draw[step=.5cm,gray,very thin] (-1.4,-1.4) grid (1.4,1.4);
\draw (-1.5,0) -- (1.5,0);
\draw (0,-1.5) -- (0,1.5);
\draw (0,0) circle [radius=1cm];
\filldraw[fill=green!20,draw=green!50!black] (0,0) -- (3mm,0mm)
arc [start angle=0, end angle=30, radius=3mm] -- cycle;
\draw[red,very thick] (30:1cm) -- +(0,-0.5);
\end{tikzpicture}
Karl used the fact sin 30◦ = 1/2. However, he very much doubts that his students know this, so it would
be nice to have a way of specifying “the point straight down from (30:1cm) that lies on the x-axis.” This
is, indeed, possible using a special syntax: Karl can write (30:1cm |- 0,0). In general, the meaning of
(hpi |- hqi) is “the intersection of a vertical line through p and a horizontal line through q.”
Next, let us draw the cosine line. One way would be to say (30:1cm |- 0,0) -- (0,0). Another way
is the following: we “continue” from where the sine ends:
\begin{tikzpicture}[scale=3]
\clip (-0.1,-0.2) rectangle (1.1,0.75);
\draw[step=.5cm,gray,very thin] (-1.4,-1.4) grid (1.4,1.4);
\draw (-1.5,0) -- (1.5,0);
\draw (0,-1.5) -- (0,1.5);
\draw (0,0) circle [radius=1cm];
\filldraw[fill=green!20,draw=green!50!black] (0,0) -- (3mm,0mm)
arc [start angle=0, end angle=30, radius=3mm] -- cycle;
\draw[red,very thick] (30:1cm) -- +(0,-0.5);
\draw[blue,very thick] (30:1cm) ++(0,-0.5) -- (0,0);
\end{tikzpicture}
Note that there is no -- between (30:1cm) and ++(0,-0.5). In detail, this path is interpreted as
follows: “First, the (30:1cm) tells me to move by pen to (cos 30◦ , 1/2). Next, there comes another coordinate
specification, so I move my pen there without drawing anything. This new point is half a unit down from the
last position, thus it is at (cos 30◦ , 0). Finally, I move the pen to the origin, but this time drawing something
(because of the --).”
To appreciate the difference between + and ++ consider the following example:
\begin{tikzpicture}
\def\rectanglepath{-- ++(1cm,0cm)
\draw (0,0) \rectanglepath;
\draw (1.5,0) \rectanglepath;
\end{tikzpicture}
-- ++(0cm,1cm)
-- ++(-1cm,0cm) -- cycle}
By comparison, when using a single +, the coordinates are different:
\begin{tikzpicture}
\def\rectanglepath{-- +(1cm,0cm)
\draw (0,0) \rectanglepath;
\draw (1.5,0) \rectanglepath;
\end{tikzpicture}
-- +(1cm,1cm)
-- +(0cm,1cm) -- cycle}
Naturally, all of this could have been written more clearly and more economically like this (either with
a single of a double +):
\tikz \draw (0,0) rectangle +(1,1)
38
(1.5,0) rectangle +(1,1);
2.16
Intersecting Paths
Karl is left with the line for tan α, which seems difficult to specify using transformations and polar coordinates. The first – and easiest – thing he can do is so simply use the coordinate (1,{tan(30)}) since Tik Z’s
math engine knows how to compute things like tan(30). Note the added braces since, otherwise, Tik Z’s
parser would think that the first closing parenthesis ends the coordinate (in general, you need to add braces
around components of coordinates when these components contain parentheses).
Karl can, however, also use a more elaborate, but also more “geometric” way of computing the length
of the orange line: He can specify intersections of paths as coordinates. The line for tan α starts at (1, 0)
and goes upward to a point that is at the intersection of a line going “up” and a line going from the origin
through (30:1cm). Such computations are made available by the intersections library.
What Karl must do is to create two “invisible” paths that intersect at the position of interest. Creating
paths that are not otherwise seen can be done using the \path command without any options like draw or
fill. Then, Karl can add the name path option to the path for later reference. Once the paths have been
constructed, Karl can use the name intersections to assign names to the coordinate for later reference.
\path [name path=upward line] (1,0) -- (1,1);
\path [name path=sloped line] (0,0) -- (30:1.5cm); % a bit longer, so that there is an intersection
\draw [name intersections={of=upward line and sloped line, by=x}]
[very thick,orange] (1,0) -- (x);
2.17
Adding Arrow Tips
Karl now wants to add the little arrow tips at the end of the axes. He has noticed that in many plots, even in
scientific journals, these arrow tips seem to be missing, presumably because the generating programs cannot
produce them. Karl thinks arrow tips belong at the end of axes. His son agrees. His students do not care
about arrow tips.
It turns out that adding arrow tips is pretty easy: Karl adds the option -> to the drawing commands for
the axes:
\begin{tikzpicture}[scale=3]
\clip (-0.1,-0.2) rectangle (1.1,1.51);
\draw[step=.5cm,gray,very thin] (-1.4,-1.4) grid (1.4,1.4);
\draw[->] (-1.5,0) -- (1.5,0);
\draw[->] (0,-1.5) -- (0,1.5);
\draw (0,0) circle [radius=1cm];
\filldraw[fill=green!20,draw=green!50!black] (0,0) -- (3mm,0mm)
arc [start angle=0, end angle=30, radius=3mm] -- cycle;
\draw[red,very thick]
(30:1cm) -- +(0,-0.5);
\draw[blue,very thick]
(30:1cm) ++(0,-0.5) -- (0,0);
\path [name path=upward line] (1,0) -- (1,1);
\path [name path=sloped line] (0,0) -- (30:1.5cm);
\draw [name intersections={of=upward line and sloped line, by=x}]
[very thick,orange] (1,0) -- (x);
\end{tikzpicture}
If Karl had used the option <- instead of ->, arrow tips would have been put at the beginning of the
path. The option <-> puts arrow tips at both ends of the path.
There are certain restrictions to the kind of paths to which arrow tips can be added. As a rule of thumb,
you can add arrow tips only to a single open “line.” For example, you cannot add tips to, say, a rectangle
or a circle. However, you can add arrow tips to curved paths and to paths that have several segments, as in
the following examples:
\begin{tikzpicture}
\draw [<->] (0,0) arc [start angle=180, end angle=30, radius=10pt];
\draw [<->] (1,0) -- (1.5cm,10pt) -- (2cm,0pt) -- (2.5cm,10pt);
\end{tikzpicture}
Karl has a more detailed look at the arrow that Tik Z puts at the end. It looks like this when he zooms
it:
. The shape seems vaguely familiar and, indeed, this is exactly the end of TEX’s standard arrow used
in something like f : A → B.
Karl likes the arrow, especially since it is not “as thick” as the arrows offered by many other packages.
However, he expects that, sometimes, he might need to use some other kinds of arrow. To do so, Karl can
39
say >=hkind of end arrow tipi, where hkind of end arrow tipi is a special arrow tip specification. For example,
if Karl says >=Stealth, then he tells Tik Z that he would like “stealth-fighter-like” arrow tips:
\begin{tikzpicture}[>=Stealth]
\draw [->] (0,0) arc [start angle=180, end angle=30, radius=10pt];
\draw [«-,very thick] (1,0) -- (1.5cm,10pt) -- (2cm,0pt) -- (2.5cm,10pt);
\end{tikzpicture}
Karl wonders whether such a military name for the arrow type is really necessary. He is not really
mollified when his son tells him that Microsoft’s PowerPoint uses the same name. He decides to have his
students discuss this at some point.
In addition to Stealth there are several other predefined kinds of arrow tips Karl can choose from, see
Section 100. Furthermore, he can define arrows types himself, if he needs new ones.
2.18
Scoping
Karl saw already that there are numerous graphic options that affect how paths are rendered. Often, he
would like to apply certain options to a whole set of graphic commands. For example, Karl might wish to
draw three paths using a thick pen, but would like everything else to be drawn “normally.”
If Karl wishes to set a certain graphic option for the whole picture, he can simply pass this option to
the \tikz command or to the {tikzpicture} environment (Gerda would pass the options to \tikzpicture
and Hans passes them to \starttikzpicture). However, if Karl wants to apply graphic options to a local
group, he put these commands inside a {scope} environment (Gerda uses \scope and \endscope, Hans
uses \startscope and \stopscope). This environment takes graphic options as an optional argument and
these options apply to everything inside the scope, but not to anything outside.
Here is an example:
\begin{tikzpicture}[ultra thick]
\draw (0,0) -- (0,1);
\begin{scope}[thin]
\draw (1,0) -- (1,1);
\draw (2,0) -- (2,1);
\end{scope}
\draw (3,0) -- (3,1);
\end{tikzpicture}
Scoping has another interesting effect: Any changes to the clipping area are local to the scope. Thus,
if you say \clip somewhere inside a scope, the effect of the \clip command ends at the end of the scope.
This is useful since there is no other way of “enlarging” the clipping area.
Karl has also already seen that giving options to commands like \draw apply only to that command.
It turns out that the situation is slightly more complex. First, options to a command like \draw are
not really options to the command, but they are “path options” and can be given anywhere on the path.
So, instead of \draw[thin] (0,0) --(1,0); one can also write \draw (0,0) [thin] --(1,0); or \draw
(0,0) --(1,0) [thin];; all of these have the same effect. This might seem strange since in the last case,
it would appear that the thin should take effect only “after” the line from (0, 0) to (1, 0) has been drawn.
However, most graphic options only apply to the whole path. Indeed, if you say both thin and thick on
the same path, the last option given will “win.”
When reading the above, Karl notices that only “most” graphic options apply to the whole path. Indeed,
all transformation options do not apply to the whole path, but only to “everything following them on the
path.” We will have a more detailed look at this in a moment. Nevertheless, all options given during a path
construction apply only to this path.
2.19
Transformations
When you specify a coordinate like (1cm,1cm), where is that coordinate placed on the page? To determine
the position, Tik Z, TEX, and pdf or PostScript all apply certain transformations to the given coordinate in
order to determine the final position on the page.
Tik Z provides numerous options that allow you to transform coordinates in Tik Z’s private coordinate
system. For example, the xshift option allows you to shift all subsequent points by a certain amount:
\tikz \draw (0,0) -- (0,0.5) [xshift=2pt] (0,0) -- (0,0.5);
40
It is important to note that you can change transformation “in the middle of a path,” a feature that is
not supported by pdf or PostScript. The reason is that Tik Z keeps track of its own transformation matrix.
Here is a more complicated example:
\begin{tikzpicture}[even odd rule,rounded
\filldraw[fill=yellow!80!black] (0,0)
[xshift=5pt,yshift=5pt]
(0,0)
[rotate=30]
(-1,-1)
\end{tikzpicture}
corners=2pt,x=10pt,y=10pt]
rectangle (1,1)
rectangle (1,1)
rectangle (2,2);
The most useful transformations are xshift and yshift for shifting, shift for shifting to a given point
as in shift={(1,0)} or shift={+(0,0)} (the braces are necessary so that TEX does not mistake the comma
for separating options), rotate for rotating by a certain angle (there is also a rotate around for rotating
around a given point), scale for scaling by a certain factor, xscale and yscale for scaling only in the xor y-direction (xscale=-1 is a flip), and xslant and yslant for slanting. If these transformation and those
that I have not mentioned are not sufficient, the cm option allows you to apply an arbitrary transformation
matrix. Karl’s students, by the way, do not know what a transformation matrix is.
2.20
Repeating Things: For-Loops
Karl’s next aim is to add little ticks on the axes at positions −1, −1/2, 1/2, and 1. For this, it would be
nice to use some kind of “loop,” especially since he wishes to do the same thing at each of these positions.
There are different packages for doing this. LATEX has its own internal command for this, pstricks comes
along with the powerful \multido command. All of these can be used together with Tik Z, so if you are
familiar with them, feel free to use them. Tik Z introduces yet another command, called \foreach, which
I introduced since I could never remember the syntax of the other packages. \foreach is defined in the
package pgffor and can be used independently Tik Z, but Tik Z includes it automatically.
In its basic form, the \foreach command is easy to use:
x = 1, x = 2, x = 3,
\foreach \x in {1,2,3} {$x =\x$, }
The general syntax is \foreach hvariablei in {hlist of valuesi} hcommandsi. Inside the hcommandsi,
the hvariablei will be assigned to the different values. If the hcommandsi do not start with a brace, everything
up to the next semicolon is used as hcommandsi.
For Karl and the ticks on the axes, he could use the following code:
\begin{tikzpicture}[scale=3]
\clip (-0.1,-0.2) rectangle (1.1,1.51);
\draw[step=.5cm,gray,very thin] (-1.4,-1.4) grid (1.4,1.4);
\filldraw[fill=green!20,draw=green!50!black] (0,0) -- (3mm,0mm)
arc [start angle=0, end angle=30, radius=3mm] -- cycle;
\draw[->] (-1.5,0) -- (1.5,0);
\draw[->] (0,-1.5) -- (0,1.5);
\draw (0,0) circle [radius=1cm];
\foreach \x in {-1cm,-0.5cm,1cm}
\draw (\x,-1pt) -- (\x,1pt);
\foreach \y in {-1cm,-0.5cm,0.5cm,1cm}
\draw (-1pt,\y) -- (1pt,\y);
\end{tikzpicture}
As a matter of fact, there are many different ways of creating the ticks. For example, Karl could have
put the \draw ...; inside curly braces. He could also have used, say,
\foreach \x in {-1,-0.5,1}
\draw[xshift=\x cm] (0pt,-1pt) -- (0pt,1pt);
Karl is curious what would happen in a more complicated situation where there are, say, 20 ticks. It
seems bothersome to explicitly mention all these numbers in the set for \foreach. Indeed, it is possible to
use ... inside the \foreach statement to iterate over a large number of values (which must, however, be
dimensionless real numbers) as in the following example:
41
\tikz \foreach \x in {1,...,10}
\draw (\x,0) circle (0.4cm);
If you provide two numbers before the ..., the \foreach statement will use their difference for the
stepping:
\tikz \foreach \x in {-1,-0.5,...,1}
\draw (\x cm,-1pt) -- (\x cm,1pt);
We can also nest loops to create interesting effects:
1,5
2,5
3,5
4,5
5,5
7,5
8,5
9,5
10,5
11,5
12,5
1,4
2,4
3,4
4,4
5,4
7,4
8,4
9,4
10,4
11,4
12,4
1,3
2,3
3,3
4,3
5,3
7,3
8,3
9,3
10,3
11,3
12,3
1,2
2,2
3,2
4,2
5,2
7,2
8,2
9,2
10,2
11,2
12,2
1,1
2,1
3,1
4,1
5,1
7,1
8,1
9,1
10,1
11,1
12,1
\begin{tikzpicture}
\foreach \x in {1,2,...,5,7,8,...,12}
\foreach \y in {1,...,5}
{
\draw (\x,\y) +(-.5,-.5) rectangle ++(.5,.5);
\draw (\x,\y) node{\x,\y};
}
\end{tikzpicture}
The \foreach statement can do even trickier stuff, but the above gives the idea.
2.21
Adding Text
Karl is, by now, quite satisfied with the picture. However, the most important parts, namely the labels, are
still missing!
Tik Z offers an easy-to-use and powerful system for adding text and, more generally, complex shapes
to a picture at specific positions. The basic idea is the following: When Tik Z is constructing a path and
encounters the keyword node in the middle of a path, it reads a node specification. The keyword node is
typically followed by some options and then some text between curly braces. This text is put inside a normal
TEX box (if the node specification directly follows a coordinate, which is usually the case, Tik Z is able to
perform some magic so that it is even possible to use verbatim text inside the boxes) and then placed at the
current position, that is, at the last specified position (possibly shifted a bit, according to the given options).
However, all nodes are drawn only after the path has been completely drawn/filled/shaded/clipped/whatever.
Text at node 2
Text at node 1
\begin{tikzpicture}
\draw (0,0) rectangle (2,2);
\draw (0.5,0.5) node [fill=yellow!80!black]
{Text at \verb!node 1!}
-- (1.5,1.5) node {Text at \verb!node 2!};
\end{tikzpicture}
Obviously, Karl would not only like to place nodes on the last specified position, but also to the left
or the right of these positions. For this, every node object that you put in your picture is equipped with
several anchors. For example, the north anchor is in the middle at the upper end of the shape, the south
anchor is at the bottom and the north east anchor is in the upper right corner. When you give the option
anchor=north, the text will be placed such that this northern anchor will lie on the current position and
the text is, thus, below the current position. Karl uses this to draw the ticks as follows:
42
1
0.5
−1
−0.5
\begin{tikzpicture}[scale=3]
\clip (-0.6,-0.2) rectangle (0.6,1.51);
\draw[step=.5cm,help lines] (-1.4,-1.4) grid (1.4,1.4);
\filldraw[fill=green!20,draw=green!50!black] (0,0) -- (3mm,0mm)
arc [start angle=0, end angle=30, radius=3mm] -- cycle;
\draw[->] (-1.5,0) -- (1.5,0);
\draw[->] (0,-1.5) -- (0,1.5);
\draw (0,0) circle [radius=1cm];
\foreach \x in {-1,-0.5,1}
\draw (\x cm,1pt) -- (\x cm,-1pt) node[anchor=north] {$\x$};
\foreach \y in {-1,-0.5,0.5,1}
\draw (1pt,\y cm) -- (-1pt,\y cm) node[anchor=east] {$\y$};
\end{tikzpicture}
1
This is quite nice, already. Using these anchors, Karl can now add most of the other text elements.
However,−0.5
Karl thinks that, though “correct,” it is quite counter-intuitive that in order to place something
below a given point, he has to use the north anchor. For this reason, there is an option called below, which
does the same as anchor=north. Similarly, above right does the same as anchor=south west. In addition,
below takes−1
an optional dimension argument. If given, the shape will additionally be shifted downwards by
the given amount. So, below=1pt can be used to put a text label below some point and, additionally shift
it 1pt downwards.
Karl is not quite satisfied with the ticks. He would like to have 1/2 or 12 shown instead of 0.5, partly to
show off the nice capabilities of TEX and Tik Z, partly because for positions like 1/3 or π it is certainly very
much preferable to have the “mathematical” tick there instead of just the “numeric” tick. His students, on
the other hand, prefer 0.5 over 1/2 since they are not too fond of fractions in general.
Karl now faces a problem: For the \foreach statement, the position \x should still be given as 0.5 since
Tik Z will not know where \frac{1}{2} is supposed to be. On the other hand, the typeset text should really
be \frac{1}{2}. To solve this problem, \foreach offers a special syntax: Instead of having one variable \x,
Karl can specify two (or even more) variables separated by a slash as in \x / \xtext. Then, the elements
in the set over which \foreach iterates must also be of the form hfirsti/hsecond i. In each iteration, \x will
be set to hfirsti and \xtext will be set to hsecond i. If no hsecond i is given, the hfirsti will be used again.
So, here is the new code for the ticks:
1
1
2
−1
− 12
\begin{tikzpicture}[scale=3]
\clip (-0.6,-0.2) rectangle (0.6,1.51);
\draw[step=.5cm,help lines] (-1.4,-1.4) grid (1.4,1.4);
\filldraw[fill=green!20,draw=green!50!black] (0,0) -- (3mm,0mm)
arc [start angle=0, end angle=30, radius=3mm] -- cycle;
\draw[->] (-1.5,0) -- (1.5,0); \draw[->] (0,-1.5) -- (0,1.5);
\draw (0,0) circle [radius=1cm];
\foreach \x/\xtext in {-1, -0.5/-\frac{1}{2}, 1}
\draw (\x cm,1pt) -- (\x cm,-1pt) node[anchor=north] {$\xtext$};
\foreach \y/\ytext in {-1, -0.5/-\frac{1}{2}, 0.5/\frac{1}{2}, 1}
\draw (1pt,\y cm) -- (-1pt,\y cm) node[anchor=east] {$\ytext$};
\end{tikzpicture}
1
Karl is quite
pleased with the result, but his son points out that this is still not perfectly satisfactory:
− 12 the circle interfere with the numbers and decrease their legibility. Karl is not very concerned
The grid and
by this (his students do not even notice), but his son insists that there is an easy solution: Karl can add the
[fill=white] option to fill out the background of the text shape with a white color.
The next
−1thing Karl wants to do is to add the labels like sin α. For this, he would like to place a label “in
the middle of the line.” To do so, instead of specifying the label node {$\sin\alpha$} directly after one
of the endpoints of the line (which would place the label at that endpoint), Karl can give the label directly
after the --, before the coordinate. By default, this places the label in the middle of the line, but the pos=
options can be used to modify this. Also, options like near start and near end can be used to modify this
position:
43
1
1
2
tan α =
sin α
−1
− 12
cos α
sin α
cos α
1
\begin{tikzpicture}[scale=3]
\clip (-2,-0.2) rectangle (2,0.8);− 1
2
\draw[step=.5cm,gray,very thin] (-1.4,-1.4) grid (1.4,1.4);
\filldraw[fill=green!20,draw=green!50!black] (0,0) -- (3mm,0mm)
arc [start angle=0, end angle=30, radius=3mm] -- cycle;
\draw[->] (-1.5,0) -- (1.5,0) coordinate (x axis);
−1
\draw[->] (0,-1.5) -- (0,1.5) coordinate
(y axis);
\draw (0,0) circle [radius=1cm];
\draw[very thick,red]
(30:1cm) -- node[left=1pt,fill=white] {$\sin \alpha$} (30:1cm |- x axis);
\draw[very thick,blue]
(30:1cm |- x axis) -- node[below=2pt,fill=white] {$\cos \alpha$} (0,0);
\path [name path=upward line] (1,0) -- (1,1);
\path [name path=sloped line] (0,0) -- (30:1.5cm);
\draw [name intersections={of=upward line and sloped line, by=t}]
[very thick,orange] (1,0) -- node [right=1pt,fill=white]
{$\displaystyle \tan \alpha \color{black}=
\frac{{\color{red}\sin \alpha}}{\color{blue}\cos \alpha}$} (t);
\draw (0,0) -- (t);
\foreach \x/\xtext in {-1, -0.5/-\frac{1}{2}, 1}
\draw (\x cm,1pt) -- (\x cm,-1pt) node[anchor=north,fill=white] {$\xtext$};
\foreach \y/\ytext in {-1, -0.5/-\frac{1}{2}, 0.5/\frac{1}{2}, 1}
\draw (1pt,\y cm) -- (-1pt,\y cm) node[anchor=east,fill=white] {$\ytext$};
\end{tikzpicture}
You can also position labels on curves and, by adding the sloped option, have them rotated such that
they match the line’s slope. Here is an example:
near start
midway
very
near
end
\begin{tikzpicture}
\draw (0,0) .. controls (6,1) and (9,1) ..
node[near start,sloped,above] {near start}
node {midway}
node[very near end,sloped,below] {very near end} (12,0);
\end{tikzpicture}
It remains to draw the explanatory text at the right of the picture. The main difficulty here lies in
limiting the width of the text “label,” which is quite long, so that line breaking is used. Fortunately, Karl
can use the option text width=6cm to get the desired effect. So, here is the full code:
44
\begin{tikzpicture}
[scale=3,line cap=round,
% Styles
axes/.style=,
important line/.style={very thick},
information text/.style={rounded corners,fill=red!10,inner sep=1ex}]
% Colors
\colorlet{anglecolor}{green!50!black}
\colorlet{sincolor}{red}
\colorlet{tancolor}{orange!80!black}
\colorlet{coscolor}{blue}
% The graphic
\draw[help lines,step=0.5cm] (-1.4,-1.4) grid (1.4,1.4);
\draw (0,0) circle [radius=1cm];
\begin{scope}[axes]
\draw[->] (-1.5,0) -- (1.5,0) node[right] {$x$} coordinate(x axis);
\draw[->] (0,-1.5) -- (0,1.5) node[above] {$y$} coordinate(y axis);
\foreach \x/\xtext in {-1, -.5/-\frac{1}{2}, 1}
\draw[xshift=\x cm] (0pt,1pt) -- (0pt,-1pt) node[below,fill=white] {$\xtext$};
\foreach \y/\ytext in {-1, -.5/-\frac{1}{2}, .5/\frac{1}{2}, 1}
\draw[yshift=\y cm] (1pt,0pt) -- (-1pt,0pt) node[left,fill=white] {$\ytext$};
\end{scope}
\filldraw[fill=green!20,draw=anglecolor] (0,0) -- (3mm,0pt)
arc [start angle=0, end angle=30, radius=3mm];
\draw (15:2mm) node[anglecolor] {$\alpha$};
\draw[important line,sincolor]
(30:1cm) -- node[left=1pt,fill=white] {$\sin \alpha$} (30:1cm |- x axis);
\draw[important line,coscolor]
(30:1cm |- x axis) -- node[below=2pt,fill=white] {$\cos \alpha$} (0,0);
\path [name path=upward line] (1,0) -- (1,1);
\path [name path=sloped line] (0,0) -- (30:1.5cm);
\draw [name intersections={of=upward line and sloped line, by=t}]
[very thick,orange] (1,0) -- node [right=1pt,fill=white]
{$\displaystyle \tan \alpha \color{black}=
\frac{{\color{red}\sin \alpha}}{\color{blue}\cos \alpha}$} (t);
\draw (0,0) -- (t);
\draw[xshift=1.85cm]
node[right,text width=6cm,information text]
{
The {\color{anglecolor} angle $\alpha$} is $30^\circ$ in the
example ($\pi/6$ in radians). The {\color{sincolor}sine of
$\alpha$}, which is the height of the red line, is
\[
{\color{sincolor} \sin \alpha} = 1/2.
\]
By the Theorem of Pythagoras ...
};
\end{tikzpicture}
2.22
Pics: The Angle Revisited
Karl expects that the code of certain parts of the picture he created might be so useful that he might wish
to reuse them in the future. A natural thing to do is to create TEX macros that store the code he wishes to
reuse. However, Tik Z offers another way that is integrated directly into its parser: pics!
A “pic” is “not quite a full picture,” hence the short name. The idea is that a pic is simply some code
that you can add to a picture at different places using the pic command whose syntax is almost identical to
the node command. The main difference is that instead of specifying some text in curly braces that should
be shown, you specify the name of a predefined picture that should be shown.
45
Defining new pics is easy enough, see Section 18, but right now we just want to use one such predefined
pic: the angle pic. As the name suggests, it is a small drawing of an angle consisting of a little wedge
and an arc together with some text (Karl needs to load the angle library and the quotes for the following
examples). What makes this pic useful is the fact that the size of the wedge will be computed automatically.
The angle pic draws an angle between the two lines BA and BC, where A, B, and C are three coordinates.
In our case, B is the origin, A is somewhere on the x-axis and C is somewhere on a line at 30◦ .
α
\begin{tikzpicture}[scale=3]
\coordinate (A) at (1,0);
\coordinate (B) at (0,0);
\coordinate (C) at (30:1cm);
\draw (A) -- (B) -- (C)
pic [draw=green!50!black, fill=green!20, angle radius=9mm,
"$\alpha$"] {angle = A--B--C};
\end{tikzpicture}
Let us see, what is happening here. First we have specified three coordinates using the \coordinate
command. It allows us to name a specific coordinate in the picture. Then comes something that starts as a
normal \draw, but then comes the pic command. This command gets lots of options and, in curly braces,
comes the most important point: We specify that we want to add an angle pic and this angle should be
between the points we named A, B, and C (we could use other names). Note that the text that we want to
be shown in the pic is specified in quotes inside the options of the pic, not inside the curly braces.
To learn more about pics, please see Section 18.
46
3
Tutorial: A Petri-Net for Hagen
In this second tutorial we explore the node mechanism of Tik Z and pgf.
Hagen must give a talk tomorrow about his favorite formalism for distributed systems: Petri nets!
Hagen used to give his talks using a blackboard and everyone seemed to be perfectly content with this.
Unfortunately, his audience has been spoiled recently with fancy projector-based presentations and there
seems to be a certain amount of peer pressure that his Petri nets should also be drawn using a graphic
program. One of the professors at his institute recommends Tik Z for this and Hagen decides to give it a try.
3.1
Problem Statement
For his talk, Hagen wishes to create a graphic that demonstrates how a net with place capacities can be
simulated by a net without capacities. The graphic should look like this, ideally:
2
2
replacement of
the capacity
by two places
s≤3
s
s̄
2
3.2
2
Setting up the Environment
For the picture Hagen will need to load the Tik Z package as did Karl in the previous tutorial. However,
Hagen will also need to load some additional library packages that Karl did not need. These library packages
contain additional definitions like extra arrow tips that are typically not needed in a picture and that need
to be loaded explicitly.
Hagen will need to load several libraries: The arrows library for the special arrow tip used in the graphic,
the decoration.pathmorphing library for the “snaking line” in the middle, the backgrounds library for the
two rectangular areas that are behind the two main parts of the picture, the fit library to easily compute
the sizes of these rectangles, and the positioning library for placing nodes relative to other nodes.
3.2.1
Setting up the Environment in LATEX
When using LATEX use:
\documentclass{article} % say
\usepackage{tikz}
\usetikzlibrary{arrows,decorations.pathmorphing,backgrounds,positioning,fit,petri}
\begin{document}
\begin{tikzpicture}
\draw (0,0) -- (1,1);
\end{tikzpicture}
\end{document}
3.2.2
Setting up the Environment in Plain TEX
When using plain TEX use:
47
%% Plain TeX file
\input tikz.tex
\usetikzlibrary{arrows,decorations.pathmorphing,backgrounds,positioning,fit,petri}
\baselineskip=12pt
\hsize=6.3truein
\vsize=8.7truein
\tikzpicture
\draw (0,0) -- (1,1);
\endtikzpicture
\bye
3.2.3
Setting up the Environment in ConTEXt
When using ConTEX, use:
%% ConTeXt file
\usemodule[tikz]
\usetikzlibrary[arrows,decorations.pathmorphing,backgrounds,positioning,fit,petri]
\starttext
\starttikzpicture
\draw (0,0) -- (1,1);
\stoptikzpicture
\stoptext
3.3
Introduction to Nodes
In principle, we already know how to create the graphics that Hagen desires (except perhaps for the snaked
line, we will come to that): We start with big light gray rectangle and then add lots of circles and small
rectangle, plus some arrows.
However, this approach has numerous disadvantages: First, it is hard to change anything at a later stage.
For example, if we decide to add more places to the Petri nets (the circles are called places in Petri net
theory), all of the coordinates change and we need to recalculate everything. Second, it is hard to read the
code for the Petri net as it is just a long and complicated list of coordinates and drawing commands – the
underlying structure of the Petri net is lost.
Fortunately, Tik Z offers a powerful mechanism for avoiding the above problems: nodes. We already came
across nodes in the previous tutorial, where we used them to add labels to Karl’s graphic. In the present
tutorial we will see that nodes are much more powerful.
A node is a small part of a picture. When a node is created, you provide a position where the node
should be drawn and a shape. A node of shape circle will be drawn as a circle, a node of shape rectangle
as a rectangle, and so on. A node may also contain some text, which is why Karl used nodes to show text.
Finally, a node can get a name for later reference.
In Hagen’s picture we will use nodes for the places and for the transitions of the Petri net (the places are
the circles, the transitions are the rectangles). Let us start with the upper half of the left Petri net. In this
upper half we have three places and two transitions. Instead of drawing three circles and two rectangles, we
use three nodes of shape circle and two nodes of shape rectangle.
\begin{tikzpicture}
\path ( 0,2) node
( 0,1) node
( 0,0) node
( 1,1) node
(-1,1) node
\end{tikzpicture}
[shape=circle,draw] {}
[shape=circle,draw] {}
[shape=circle,draw] {}
[shape=rectangle,draw] {}
[shape=rectangle,draw] {};
Hagen notes that this does not quite look like the final picture, but it seems like a good first step.
Let us have a more detailed look at the code. The whole picture consists of a single path. Ignoring the
node operations, there is not much going on in this path: It is just a sequence of coordinates with nothing
“happening” between them. Indeed, even if something were to happen like a line-to or a curve-to, the \path
command would not “do” anything with the resulting path. So, all the magic must be in the node commands.
In the previous tutorial we learned that a node will add a piece of text at the last coordinate. Thus,
each of the five nodes is added at a different position. In the above code, this text is empty (because of the
empty {}). So, why do we see anything at all? The answer is the draw option for the node operation: It
causes the “shape around the text” to be drawn.
48
So, the code (0,2) node [shape=circle,draw] {} means the following: “In the main path, add a
move-to to the coordinate (0,2). Then, temporarily suspend the construction of the main path while the
node is built. This node will be a circle around an empty text. This circle is to be drawn, but not filled or
otherwise used. Once this whole node is constructed, it is saved until after the main path is finished. Then,
it is drawn.” The following (0,1) node [shape=circle,draw] {} then has the following effect: “Continue
the main path with a move-to to (0,1). Then construct a node at this position also. This node is also
shown after the main path is finished.” And so on.
3.4
Placing Nodes Using the At Syntax
Hagen now understands how the node operation adds nodes to the path, but it seems a bit silly to create a
path using the \path operation, consisting of numerous superfluous move-to operations, only to place nodes.
He is pleased to learn that there are ways to add nodes in a more sensible manner.
First, the node operation allows one to add at (hcoordinatei) in order to directly specify where the node
should be placed, sidestepping the rule that nodes are placed on the last coordinate. Hagen can then write
the following:
\begin{tikzpicture}
\path node at ( 0,2)
node at ( 0,1)
node at ( 0,0)
node at ( 1,1)
node at (-1,1)
\end{tikzpicture}
[shape=circle,draw] {}
[shape=circle,draw] {}
[shape=circle,draw] {}
[shape=rectangle,draw] {}
[shape=rectangle,draw] {};
Now Hagen is still left with a single empty path, but at least the path no longer contains strange move-tos.
It turns out that this can be improved further: The \node command is an abbreviation for \path node,
which allows Hagen to write:
\begin{tikzpicture}
\node at ( 0,2) [circle,draw] {};
\node at ( 0,1) [circle,draw] {};
\node at ( 0,0) [circle,draw] {};
\node at ( 1,1) [rectangle,draw] {};
\node at (-1,1) [rectangle,draw] {};
\end{tikzpicture}
Hagen likes this syntax much better than the previous one. Note that Hagen has also omitted the shape=
since, like color=, Tik Z allows you to omit the shape= if there is no confusion.
3.5
Using Styles
Feeling adventurous, Hagen tries to make the nodes look nicer. In the final picture, the circles and rectangle
should be filled with different colors, resulting in the following code:
\begin{tikzpicture}[thick]
\node at ( 0,2) [circle,draw=blue!50,fill=blue!20] {};
\node at ( 0,1) [circle,draw=blue!50,fill=blue!20] {};
\node at ( 0,0) [circle,draw=blue!50,fill=blue!20] {};
\node at ( 1,1) [rectangle,draw=black!50,fill=black!20] {};
\node at (-1,1) [rectangle,draw=black!50,fill=black!20] {};
\end{tikzpicture}
While this looks nicer in the picture, the code starts to get a bit ugly. Ideally, we would like our code
to transport the message “there are three places and two transitions” and not so much which filling colors
should be used.
To solve this problem, Hagen uses styles. He defines a style for places and another style for transitions:
\begin{tikzpicture}
[place/.style={circle,draw=blue!50,fill=blue!20,thick},
transition/.style={rectangle,draw=black!50,fill=black!20,thick}]
\node at ( 0,2) [place] {};
\node at ( 0,1) [place] {};
\node at ( 0,0) [place] {};
\node at ( 1,1) [transition] {};
\node at (-1,1) [transition] {};
\end{tikzpicture}
49
3.6
Node Size
Before Hagen starts naming and connecting the nodes, let us first make sure that the nodes get their final
appearance. They are still too small. Indeed, Hagen wonders why they have any size at all, after all, the
text is empty. The reason is that Tik Z automatically adds some space around the text. The amount is set
using the option inner sep. So, to increase the size of the nodes, Hagen could write:
\begin{tikzpicture}
[inner sep=2mm,
place/.style={circle,draw=blue!50,fill=blue!20,thick},
transition/.style={rectangle,draw=black!50,fill=black!20,thick}]
\node at ( 0,2) [place] {};
\node at ( 0,1) [place] {};
\node at ( 0,0) [place] {};
\node at ( 1,1) [transition] {};
\node at (-1,1) [transition] {};
\end{tikzpicture}
However, this is not really the best way to achieve the desired effect. It is much better to use the
minimum size option instead. This option allows Hagen to specify a minimum size that the node should
have. If the node actually needs to be bigger because of a longer text, it will be larger, but if the text
is empty, then the node will have minimum size. This option is also useful to ensure that several nodes
containing different amounts of text have the same size. The options minimum height and minimum width
allow you to specify the minimum height and width independently.
So, what Hagen needs to do is to provide minimum size for the nodes. To be on the safe side, he also
sets inner sep=0pt. This ensures that the nodes will really have size minimum size and not, for very small
minimum sizes, the minimal size necessary to encompass the automatically added space.
\begin{tikzpicture}
[place/.style={circle,draw=blue!50,fill=blue!20,thick,
inner sep=0pt,minimum size=6mm},
transition/.style={rectangle,draw=black!50,fill=black!20,thick,
inner sep=0pt,minimum size=4mm}]
\node at ( 0,2) [place] {};
\node at ( 0,1) [place] {};
\node at ( 0,0) [place] {};
\node at ( 1,1) [transition] {};
\node at (-1,1) [transition] {};
\end{tikzpicture}
3.7
Naming Nodes
Hagen’s next aim is to connect the nodes using arrows. This seems like a tricky business since the arrows
should not start in the middle of the nodes, but somewhere on the border and Hagen would very much like
to avoid computing these positions by hand.
Fortunately, pgf will perform all the necessary calculations for him. However, he first has to assign
names to the nodes so that he can reference them later on.
There are two ways to name a node. The first is to use the name= option. The second method is to write
the desired name in parentheses after the node operation. Hagen thinks that this second method seems
strange, but he will soon change his opinion.
% ... set up styles
\begin{tikzpicture}
\node (waiting 1) at ( 0,2)
\node (critical 1) at ( 0,1)
\node (semaphore) at ( 0,0)
\node (leave critical) at ( 1,1)
\node (enter critical) at (-1,1)
\end{tikzpicture}
[place] {};
[place] {};
[place] {};
[transition] {};
[transition] {};
Hagen is pleased to note that the names help in understanding the code. Names for nodes can be
pretty arbitrary, but they should not contain commas, periods, parentheses, colons, and some other special
characters. However, they can contain underscores and hyphens.
The syntax for the node operation is quite liberal with respect to the order in which node names, the at
specifier, and the options must come. Indeed, you can even have multiple option blocks between the node
50
and the text in curly braces, they accumulate. You can rearrange them arbitrarily and perhaps the following
might be preferable:
\begin{tikzpicture}
\node[place]
\node[place]
\node[place]
\node[transition]
\node[transition]
\end{tikzpicture}
3.8
(waiting 1)
(critical 1)
(semaphore)
(leave critical)
(enter critical)
at
at
at
at
at
( 0,2)
( 0,1)
( 0,0)
( 1,1)
(-1,1)
{};
{};
{};
{};
{};
Placing Nodes Using Relative Placement
Although Hagen still wishes to connect the nodes, he first wishes to address another problem again: The
placement of the nodes. Although he likes the at syntax, in this particular case he would prefer placing the
nodes “relative to each other.” So, Hagen would like to say that the critical 1 node should be below the
waiting 1 node, wherever the waiting 1 node might be. There are different ways of achieving this, but
the nicest one in Hagen’s case is the below option:
\begin{tikzpicture}
\node[place]
\node[place]
\node[place]
\node[transition]
\node[transition]
\end{tikzpicture}
(waiting)
(critical)
(semaphore)
(leave critical)
(enter critical)
[below=of waiting]
[below=of critical]
[right=of critical]
[left=of critical]
{};
{};
{};
{};
{};
With the positioning library loaded, when an option like below is followed by of, then the position
of the node is shifted in such a manner that it is placed at the distance node distance in the specified
direction of the given direction. The node distance is either the distance between the centers of the nodes
(when the on grid option is set to true) or the distance between the borders (when the on grid option is
set to false, which is the default).
Even though the above code has the same effect as the earlier code, Hagen can pass it to his colleagues
who will be able to just read and understand it, perhaps without even having to see the picture.
3.9
Adding Labels Next to Nodes
Before we have a look at how Hagen can connect the nodes, let us add the capacity “s ≤ 3” to the bottom
node. For this, two approaches are possible:
1. Hagen can just add a new node above the north anchor of the semaphore node.
\begin{tikzpicture}
\node[place]
\node[place]
\node[place]
\node[transition]
\node[transition]
s≤3
(waiting)
(critical)
(semaphore)
(leave critical)
(enter critical)
[below=of waiting]
[below=of critical]
[right=of critical]
[left=of critical]
{};
{};
{};
{};
{};
\node [red,above] at (semaphore.north) {$s\le 3$};
\end{tikzpicture}
This is a general approach that will “always work.”
2. Hagen can use the special label option. This option is given to a node and it causes another node
to be added next to the node where the option is given. Here is the idea: When we construct the
semaphore node, we wish to indicate that we want another node with the capacity above it. For this,
51
we use the option label=above:$s\le 3$. This option is interpreted as follows: We want a node
above the semaphore node and this node should read “s ≤ 3.” Instead of above we could also use
things like below left before the colon or a number like 60.
\begin{tikzpicture}
\node[place]
(waiting)
\node[place]
(critical)
\node[place]
(semaphore)
{};
[below=of waiting] {};
[below=of critical,
label=above:$s\le3$] {};
\node[transition] (leave critical) [right=of critical] {};
\node[transition] (enter critical) [left=of critical] {};
\end{tikzpicture}
s≤3
It is also possible to give multiple label options, this causes multiple labels to be drawn.
60◦
\tikz
\node [circle,draw,label=60:$60^\circ$,label=below:$-90^\circ$] {my circle};
my circle
−90◦
Hagen is not fully satisfied with the label option since the label is not red. To achieve this, he has
two options: First, he can redefine the every label style. Second, he can add options to the label’s
node. These options are given following the label=, so he would write label=[red]above:$s\le3$.
However, this does not quite work since TEX thinks that the ] closes the whole option list of the
semaphore node. So, Hagen has to add braces and writes label={[red]above:$s\le3$}. Since this
looks a bit ugly, Hagen decides to redefine the every label style.
\begin{tikzpicture}[every label/.style={red}]
\node[place]
(waiting)
{};
\node[place]
(critical)
[below=of waiting] {};
\node[place]
(semaphore)
[below=of critical,
label=above:$s\le3$] {};
\node[transition] (leave critical) [right=of critical] {};
\node[transition] (enter critical) [left=of critical] {};
\end{tikzpicture}
s≤3
3.10
Connecting Nodes
It is now high time to connect the nodes. Let us start with something simple, namely with the straight line
from enter critical to critical. We want this line to start at the right side of enter critical and to
end at the left side of critical. For this, we can use the anchors of the nodes. Every node defines a whole
bunch of anchors that lie on its border or inside it. For example, the center anchor is at the center of the
node, the west anchor is on the left of the node, and so on. To access the coordinate of a node, we use a
coordinate that contains the node’s name followed by a dot, followed by the anchor’s name:
52
\begin{tikzpicture}
\node[place]
(waiting)
\node[place]
(critical)
[below=of waiting]
\node[place]
(semaphore)
[below=of critical]
\node[transition] (leave critical) [right=of critical]
\node[transition] (enter critical) [left=of critical]
\draw [->] (critical.west) -- (enter critical.east);
\end{tikzpicture}
{};
{};
{};
{};
{};
Next, let us tackle the curve from waiting to enter critical. This can be specified using curves and
controls:
\begin{tikzpicture}
\node[place]
(waiting)
{};
\node[place]
(critical)
[below=of waiting] {};
\node[place]
(semaphore)
[below=of critical] {};
\node[transition] (leave critical) [right=of critical] {};
\node[transition] (enter critical) [left=of critical] {};
\draw [->] (enter critical.east) -- (critical.west);
\draw [->] (waiting.west) .. controls +(left:5mm) and +(up:5mm)
.. (enter critical.north);
\end{tikzpicture}
Hagen sees how he can now add all his edges, but the whole process seems a but awkward and not very
flexible. Again, the code seems to obscure the structure of the graphic rather than showing it.
So, let us start improving the code for the edges. First, Hagen can leave out the anchors:
\begin{tikzpicture}
\node[place]
(waiting)
{};
\node[place]
(critical)
[below=of waiting] {};
\node[place]
(semaphore)
[below=of critical] {};
\node[transition] (leave critical) [right=of critical] {};
\node[transition] (enter critical) [left=of critical] {};
\draw [->] (enter critical) -- (critical);
\draw [->] (waiting) .. controls +(left:8mm) and +(up:8mm)
.. (enter critical);
\end{tikzpicture}
Hagen is a bit surprised that this works. After all, how did Tik Z know that the line from enter
critical to critical should actually start on the borders? Whenever Tik Z encounters a whole node name
as a “coordinate,” it tries to “be smart” about the anchor that it should choose for this node. Depending on
what happens next, Tik Z will choose an anchor that lies on the border of the node on a line to the next
coordinate or control point. The exact rules are a bit complex, but the chosen point will usually be correct
– and when it is not, Hagen can still specify the desired anchor by hand.
Hagen would now like to simplify the curve operation somehow. It turns out that this can be accomplished
using a special path operation: the to operation. This operation takes many options (you can even define
new ones yourself). One pair of options is useful for Hagen: The pair in and out. These options take angles
at which a curve should leave or reach the start or target coordinates. Without these options, a straight line
is drawn:
\begin{tikzpicture}
\node[place]
(waiting)
{};
\node[place]
(critical)
[below=of waiting] {};
\node[place]
(semaphore)
[below=of critical] {};
\node[transition] (leave critical) [right=of critical] {};
\node[transition] (enter critical) [left=of critical] {};
\draw [->] (enter critical) to
(critical);
\draw [->] (waiting)
to [out=180,in=90] (enter critical);
\end{tikzpicture}
53
There is another option for the to operation, that is even better suited to Hagen’s problem: The
bend right option. This option also takes an angle, but this angle only specifies the angle by which
the curve is bent to the right:
\begin{tikzpicture}
\node[place]
(waiting)
{};
\node[place]
(critical)
[below=of waiting] {};
\node[place]
(semaphore)
[below=of critical] {};
\node[transition] (leave critical) [right=of critical] {};
\node[transition] (enter critical) [left=of critical] {};
\draw [->] (enter critical) to
(critical);
\draw [->] (waiting)
to [bend right=45] (enter critical);
\draw [->] (enter critical) to [bend right=45] (semaphore);
\end{tikzpicture}
It is now time for Hagen to learn about yet another way of specifying edges: Using the edge path
operation. This operation is very similar to the to operation, but there is one important difference: Like a
node the edge generated by the edge operation is not part of the main path, but is added only later. This
may not seem very important, but it has some nice consequences. For example, every edge can have its own
arrow tips and its own color and so on and, still, all the edges can be given on the same path. This allows
Hagen to write the following:
\begin{tikzpicture}
\node[place]
(waiting)
\node[place]
(critical)
[below=of waiting]
\node[place]
(semaphore)
[below=of critical]
\node[transition] (leave critical) [right=of critical]
\node[transition] (enter critical) [left=of critical]
edge [->]
(critical)
edge [<-,bend left=45] (waiting)
edge [->,bend right=45] (semaphore);
\end{tikzpicture}
{};
{};
{};
{};
{}
Each edge caused a new path to be constructed, consisting of a to between the node enter critical
and the node following the edge command.
The finishing touch is to introduce two styles pre and post and to use the bend angle=45 option to set
the bend angle once and for all:
% Styles place and transition as before
\begin{tikzpicture}
[bend angle=45,
pre/.style={<-,shorten <=1pt,>=stealth’,semithick},
post/.style={->,shorten >=1pt,>=stealth’,semithick}]
\node[place]
\node[place]
\node[place]
\node[transition]
edge [pre]
edge [post,bend
edge [pre, bend
\node[transition]
edge [post]
edge [pre, bend
edge [post,bend
\end{tikzpicture}
3.11
(waiting)
(critical)
(semaphore)
{};
[below=of waiting] {};
[below=of critical] {};
(leave critical) [right=of critical] {}
(critical)
right] (waiting)
left] (semaphore);
(enter critical) [left=of critical] {}
(critical)
left] (waiting)
right] (semaphore);
Adding Labels Next to Lines
The next thing that Hagen needs to add is the “2” at the arcs. For this Hagen can use Tik Z’s automatic
node placement: By adding the option auto, Tik Z will position nodes on curves and lines in such a way that
they are not on the curve but next to it. Adding swap will mirror the label with respect to the line. Here is
a general example:
54
120◦
1’
1
0◦
2’ 2
3
240◦
3’
\begin{tikzpicture}[auto,bend right]
\node (a) at (0:1) {$0^\circ$};
\node (b) at (120:1) {$120^\circ$};
\node (c) at (240:1) {$240^\circ$};
\draw (a) to node {1} node [swap] {1’} (b)
(b) to node {2} node [swap] {2’} (c)
(c) to node {3} node [swap] {3’} (a);
\end{tikzpicture}
What is happening here? The nodes are given somehow inside the to operation! When this is done, the
node is placed on the middle of the curve or line created by the to operation. The auto option then causes
the node to be moved in such a way that it does not lie on the curve, but next to it. In the example we
provide even two nodes on each to operation.
For Hagen that auto option is not really necessary since the two “2” labels could also easily be placed
“by hand.” However, in a complicated plot with numerous edges automatic placement can be a blessing.
2
% Styles as before
\begin{tikzpicture}[bend angle=45]
\node[place]
(waiting)
\node[place]
(critical)
\node[place]
(semaphore)
\node[transition]
edge [pre]
edge [post,bend
edge [pre, bend
\node[transition]
edge [post]
edge [pre, bend
edge [post,bend
\end{tikzpicture}
3.12
{};
[below=of waiting] {};
[below=of critical] {};
(leave critical) [right=of critical] {}
(critical)
right] node[auto,swap] {2} (waiting)
left]
(semaphore);
(enter critical) [left=of critical] {}
(critical)
left]
(waiting)
right]
(semaphore);
Adding the Snaked Line and Multi-Line Text
With the node mechanism Hagen can now easily create the two Petri nets. What he is unsure of is how he
can create the snaked line between the nets.
For this he can use a decoration. To draw the snaked line, Hagen only needs to set the two options
decoration=snake and decorate on the path. This causes all lines of the path to be replaced by snakes.
It is also possible to use snakes only in certain parts of a path, but Hagen will not need this.
\begin{tikzpicture}
\draw [->,decorate,decoration=snake] (0,0) -- (2,0);
\end{tikzpicture}
Well, that does not look quite right, yet. The problem is that the snake happens to end exactly at the
position where the arrow begins. Fortunately, there is an option that helps here. Also, the snake should be
a bit smaller, which can be influenced by even more options.
\begin{tikzpicture}
\draw [->,decorate,
decoration={snake,amplitude=.4mm,segment length=2mm,post length=1mm}]
(0,0) -- (3,0);
\end{tikzpicture}
Now Hagen needs to add the text above the snake. This text is a bit challenging since it is a multi-line
text. Hagen has two options for this: First, he can specify an align=center and then use the \\ command
to enforce the line breaks at the desired positions.
replacement of
the capacity
by two places
\begin{tikzpicture}
\draw [->,decorate,
decoration={snake,amplitude=.4mm,segment length=2mm,post length=1mm}]
(0,0) -- (3,0)
node [above,align=center,midway]
{
replacement of\\
the \textcolor{red}{capacity}\\
by \textcolor{red}{two places}
};
\end{tikzpicture}
55
Instead of specifying the line breaks “by hand,” Hagen can also specify a width for the text and let TEX
perform the line breaking for him:
replacement of
the capacity
by two places
3.13
\begin{tikzpicture}
\draw [->,decorate,
decoration={snake,amplitude=.4mm,segment length=2mm,post length=1mm}]
(0,0) -- (3,0)
node [above,text width=3cm,align=center,midway]
{
replacement of the \textcolor{red}{capacity} by
\textcolor{red}{two places}
};
\end{tikzpicture}
Using Layers: The Background Rectangles
Hagen still needs to add the background rectangles. These are a bit tricky: Hagen would like to draw the
rectangles after the Petri nets are finished. The reason is that only then can he conveniently refer to the
coordinates that make up the corners of the rectangle. If Hagen draws the rectangle first, then he needs to
know the exact size of the Petri net – which he does not.
The solution is to use layers. When the background library is loaded, Hagen can put parts of his picture
inside a scope with the on background layer option. Then this part of the picture becomes part of the
layer that is given as an argument to this environment. When the {tikzpicture} environment ends, the
layers are put on top of each other, starting with the background layer. This causes everything drawn on
the background layer to be behind the main text.
The next tricky question is, how big should the rectangle be? Naturally, Hagen can compute the size
“by hand” or using some clever observations concerning the x- and y-coordinates of the nodes, but it would
be nicer to just have Tik Z compute a rectangle into which all the nodes “fit.” For this, the fit library can
be used. It defines the fit options, which, when given to a node, causes the node to be resized and shifted
such that it exactly covers all the nodes and coordinates given as parameters to the fit option.
2
% Styles as before
\begin{tikzpicture}[bend angle=45]
\node[place]
(waiting)
\node[place]
(critical)
\node[place]
(semaphore)
\node[transition]
edge [pre]
edge [post,bend
edge [pre, bend
\node[transition]
edge [post]
edge [pre, bend
edge [post,bend
{};
[below=of waiting] {};
[below=of critical] {};
(leave critical) [right=of critical] {}
(critical)
right] node[auto,swap] {2} (waiting)
left]
(semaphore);
(enter critical) [left=of critical] {}
(critical)
left]
(waiting)
right]
(semaphore);
\begin{scope}[on background layer]
\node [fill=black!30,fit=(waiting) (critical) (semaphore)
(leave critical) (enter critical)] {};
\end{scope}
\end{tikzpicture}
3.14
The Complete Code
Hagen has now finally put everything together. Only then does he learn that there is already a library for
drawing Petri nets! It turns out that this library mainly provides the same definitions as Hagen did. For
example, it defines a place style in a similar way as Hagen did. Adjusting the code so that it uses the library
shortens Hagen code a bit, as shown in the following.
First, Hagen needs less style definitions, but he still needs to specify the colors of places and transitions.
\begin{tikzpicture}
[node distance=1.3cm,on grid,>=stealth’,bend angle=45,auto,
every place/.style=
{minimum size=6mm,thick,draw=blue!75,fill=blue!20},
every transition/.style={thick,draw=black!75,fill=black!20},
red place/.style=
{place,draw=red!75,fill=red!20},
every label/.style=
{red}]
56
Now comes the code for the nets:
2
s≤3
2
2
s
s̄
2
\node
\node
\node
\node
\node
[place,tokens=1]
[place]
[place]
[place]
[place,tokens=1]
(w1)
(c1)
(s)
(c2)
(w2)
[below=of
[below=of
[below=of
[below=of
{};
w1]
{};
c1,label=above:$s\le 3$] {};
s]
{};
c2]
{};
\node [transition] (e1) [left=of c1] {}
edge [pre,bend left]
(w1)
edge [post,bend right]
(s)
edge [post]
(c1);
\node [transition] (e2) [left=of c2] {}
edge [pre,bend right]
(w2)
edge [post,bend left]
(s)
edge [post]
(c2);
\node [transition] (l1) [right=of c1] {}
edge [pre]
(c1)
edge [pre,bend left]
(s)
edge [post,bend right] node[swap] {2} (w1);
\node [transition] (l2) [right=of c2] {}
edge [pre]
(c2)
edge [pre,bend right]
(s)
edge [post,bend left] node {2}
(w2);
\begin{scope}[xshift=6cm]
\node [place,tokens=1]
\node [place]
\node [red place]
[label=left:$s$]
\node [red place,tokens=3]
[label=right:$\bar
\node [place]
\node [place,tokens=1]
\node [transition] (e1’)
edge [pre,bend left]
edge [post]
edge [pre]
edge [post]
\node [transition] (e2’)
edge [pre,bend right]
edge [post]
edge [pre]
edge [post]
\node [transition] (l1’)
edge [pre]
edge [pre]
edge [post]
edge [post,bend right]
\node [transition] (l2’)
edge [pre]
edge [pre]
edge [post]
edge [post,bend left]
\end{scope}
(w1’)
{};
(c1’) [below=of w1’]
{};
(s1’) [below=of c1’,xshift=-5mm]
{};
(s2’) [below=of c1’,xshift=5mm]
s$]
{};
(c2’) [below=of s1’,xshift=5mm] {};
(w2’) [below=of c2’]
{};
[left=of c1’] {}
(w1’)
(s1’)
(s2’)
(c1’);
[left=of c2’] {}
(w2’)
(s1’)
(s2’)
(c2’);
[right=of c1’] {}
(c1’)
(s1’)
(s2’)
node[swap] {2} (w1’);
[right=of c2’] {}
(c2’)
(s1’)
(s2’)
node {2}
(w2’);
The code for the background and the snake is the following:
\begin{scope}[on background layer]
\node (r1) [fill=black!10,rounded corners,fit=(w1)(w2)(e1)(e2)(l1)(l2)] {};
\node (r2) [fill=black!10,rounded corners,fit=(w1’)(w2’)(e1’)(e2’)(l1’)(l2’)] {};
\end{scope}
\draw [shorten >=1mm,-to,thick,decorate,
decoration={snake,amplitude=.4mm,segment length=2mm,
pre=moveto,pre length=1mm,post length=2mm}]
(r1) -- (r2) node [above=1mm,midway,text width=3cm,align=center]
{replacement of the \textcolor{red}{capacity} by \textcolor{red}{two places}};
\end{tikzpicture}
57
4
Tutorial: Euclid’s Amber Version of the Elements
In this third tutorial we have a look at how Tik Z can be used to draw geometric constructions.
Euclid is currently quite busy writing his new book series, whose working title is “Elements” (Euclid is
not quite sure whether this title will convey the message of the series to future generations correctly, but he
intends to change the title before it goes to the publisher). Up to know, he wrote down his text and graphics
on papyrus, but his publisher suddenly insists that he must submit in electronic form. Euclid tries to argue
with the publisher that electronics will only be discovered thousands of years later, but the publisher informs
him that the use of papyrus is no longer cutting edge technology and Euclid will just have to keep up with
modern tools.
Slightly disgruntled, Euclid starts converting his papyrus entitled “Book I, Proposition I” to an amber
version.
4.1
Book I, Proposition I
The drawing on his papyrus looks like this:1
Proposition I
To construct an equilateral triangle on a given finite straight line.
C
D
A
B
E
Let AB be the given finite straight line. It is required to construct an
equilateral triangle on the straight line AB.
Describe the circle BCD with center A and radius AB. Again describe
the circle ACE with center B and radius BA. Join the straight lines
CA and CB from the point C at which the circles cut one another to
the points A and B.
Now, since the point A is the center of the circle CDB, therefore AC
equals AB. Again, since the point B is the center of the circle CAE,
therefore BC equals BA. But AC was proved equal to AB, therefore
each of the straight lines AC and BC equals AB. And things which
equal the same thing also equal one another, therefore AC also equals
BC. Therefore the three straight lines AC, AB, and BC equal one
another. Therefore the triangle ABC is equilateral, and it has been
constructed on the given finite straight line AB.
Let us have a look at how Euclid can turn this into Tik Z code.
4.1.1
Setting up the Environment
As in the previous tutorials, Euclid needs to load Tik Z, together with some libraries. These libraries are
calc, intersections, through, and backgrounds. Depending on which format he uses, Euclid would use
one of the following in the preamble:
% For LaTeX:
\usepackage{tikz}
\usetikzlibrary{calc,intersections,through,backgrounds}
% For plain TeX:
\input tikz.tex
\usetikzlibrary{calc,intersections,through,backgrounds}
% For ConTeXt:
\usemodule[tikz]
\usetikzlibrary[calc,intersections,through,backgrounds]
1 The text is taken from the wonderful interactive version of Euclid’s Elements by David E. Joyce, to be found on his website
at Clark University.
58
4.1.2
The Line AB
The first part of the picture that Euclid wishes to draw is the line AB. That is easy enough, something like
\draw (0,0) --(2,1); might do. However, Euclid does not wish to reference the two points A and B as
(0, 0) and (2, 1) subsequently. Rather, he wishes to just write A and B. Indeed, the whole point of his book
is that the points A and B can be arbitrary and all other points (like C) are constructed in terms of their
positions. It would not do if Euclid were to write down the coordinates of C explicitly.
So, Euclid starts with defining two coordinates using the \coordinate command:
\begin{tikzpicture}
\coordinate (A) at (0,0);
\coordinate (B) at (1.25,0.25);
\draw[blue] (A) -- (B);
\end{tikzpicture}
That was easy enough. What is missing at this point are the labels for the coordinates. Euclid does not
want them on the points, but next to them. He decides to use the label option:
A
B
\begin{tikzpicture}
\coordinate [label=left:\textcolor{blue}{$A$}] (A) at (0,0);
\coordinate [label=right:\textcolor{blue}{$B$}] (B) at (1.25,0.25);
\draw[blue] (A) -- (B);
\end{tikzpicture}
At this point, Euclid decides that it would be even nicer if the points A and B were in some sense
“random.” Then, neither Euclid nor the reader can make the mistake of taking “anything for granted”
concerning these position of these points. Euclid is pleased to learn that there is a rand function in Tik Z
that does exactly what he needs: It produces a number between −1 and 1. Since Tik Z can do a bit of math,
Euclid can change the coordinates of the points as follows:
\coordinate [...] (A) at (0+0.1*rand,0+0.1*rand);
\coordinate [...] (B) at (1.25+0.1*rand,0.25+0.1*rand);
This works fine. However, Euclid is not quite satisfied since he would prefer that the “main coordinates”
(0, 0) and (1.25, 0.25) are “kept separate” from the perturbation 0.1(rand , rand ). This means, he would like
to specify that coordinate A as “The point that is at (0, 0) plus one tenth of the vector (rand , rand ).”
It turns out that the calc library allows him to do exactly this kind of computation. When this library is
loaded, you can use special coordinates that start with ($ and end with $) rather than just ( and ). Inside
these special coordinates you can give a linear combination of coordinates. (Note that the dollar signs are
only intended to signal that a “computation” is going on; no mathematical typesetting is done.)
The new code for the coordinates is the following:
\coordinate [...] (A) at ($ (0,0) + .1*(rand,rand) $);
\coordinate [...] (B) at ($ (1.25,0.25) + .1*(rand,rand) $);
Note that if a coordinate in such a computation has a factor (like .1), you must place a * directly before
the opening parenthesis of the coordinate. You can nest such computations.
4.1.3
The Circle Around A
The first tricky construction is the circle around A. We will see later how to do this in a very simple manner,
but first let us do it the “hard” way.
The idea is the following: We draw a circle around the point A whose radius is given by the length of
the line AB. The difficulty lies in computing the length of this line.
Two ideas “nearly” solve this problem: First, we can write ($ (A) - (B) $) for the vector that is the
difference between A and B. All we need is the length of this vector. Second, given two
p numbers x and
y, one can write veclen(x,y) inside a mathematical expression. This gives the value x2 + y 2 , which is
exactly the desired length.
The only remaining problem is to access the x- and y-coordinate of the vector AB. For this, we need
a new concept: the let operation. A let operation can be given anywhere on a path where a normal path
operation like a line-to or a move-to is expected. The effect of a let operation is to evaluate some coordinates
and to assign the results to special macros. These macros make it easy to access the x- and y-coordinates of
the coordinates.
Euclid would write the following:
59
B
A
\begin{tikzpicture}
\coordinate [label=left:$A$] (A) at (0,0);
\coordinate [label=right:$B$] (B) at (1.25,0.25);
\draw (A) -- (B);
\draw (A) let
\p1 = ($ (B) - (A) $)
in
circle ({veclen(\x1,\y1)});
\end{tikzpicture}
Each assignment in a let operation starts with \p, usually followed by a hdigiti. Then comes an equal
sign and a coordinate. The coordinate is evaluated and the result is stored internally. From then on you can
use the following expressions:
1. \xhdigiti yields the x-coordinate of the resulting point.
2. \yhdigiti yields the y-coordinate of the resulting point.
3. \phdigiti yields the same as \xhdigiti,\yhdigiti.
You can have multiple assignments in a let operation, just separate them with commas. In later assignments
you can already use the results of earlier assignments.
Note that \p1 is not a coordinate in the usual sense. Rather, it just expands to a string like 10pt,20pt.
So, you cannot write, for instance, (\p1.center) since this would just expand to (10pt,20pt.center),
which makes no sense.
Next, we want to draw both circles at the same time. Each time the radius is veclen(\x1,\y1). It seems
natural to compute this radius only once. For this, we can also use a let operation: Instead of writing \p1
= ..., we write \n2 = .... Here, “n” stands for “number” (while “p” stands for “point”). The assignment
of a number should be followed by a number in curly braces.
A
B
\begin{tikzpicture}
\coordinate [label=left:$A$] (A) at (0,0);
\coordinate [label=right:$B$] (B) at (1.25,0.25);
\draw (A) -- (B);
\draw let \p1 = ($ (B) - (A) $),
\n2 = {veclen(\x1,\y1)}
in
(A) circle (\n2)
(B) circle (\n2);
\end{tikzpicture}
In the above example, you may wonder, what \n1 would yield? The answer is that it would be undefined
– the \p, \x, and \y macros refer to the same logical point, while the \n macro has “its own namespace.”
We could even have replaced \n2 in the example by \n1 and it would still work. Indeed, the digits following
these macros are just normal TEX parameters. We could also use a longer name, but then we have to use
curly braces:
A
B
\begin{tikzpicture}
\coordinate [label=left:$A$] (A) at (0,0);
\coordinate [label=right:$B$] (B) at (1.25,0.25);
\draw (A) -- (B);
\draw let \p1
= ($ (B) - (A) $),
\n{radius} = {veclen(\x1,\y1)}
in
(A) circle (\n{radius})
(B) circle (\n{radius});
\end{tikzpicture}
At the beginning of this section it was promised that there is an easier way to create the desired circle.
The trick is to use the through library. As the name suggests, it contains code for creating shapes that go
through a given point.
The option that we are looking for is circle through. This option is given to a node and has the
following effects: First, it causes the node’s inner and outer separations to be set to zero. Then it sets the
shape of the node to circle. Finally, it sets the radius of the node such that it goes through the parameter
given to circle through. This radius is computed in essentially the same way as above.
60
D
B
A
\begin{tikzpicture}
\coordinate [label=left:$A$] (A) at (0,0);
\coordinate [label=right:$B$] (B) at (1.25,0.25);
\draw (A) -- (B);
\node [draw,circle through=(B),label=left:$D$] at (A) {};
\end{tikzpicture}
4.1.4
The Intersection of the Circles
Euclid can now draw the line and the circles. The final problem is to compute the intersection of the two
circles. This computation is a bit involved if you want to do it “by hand.” Fortunately, the intersection
library allows us to compute the intersection of arbitrary paths.
The idea is simple: First, you “name” two paths using the name path option. Then, at some later
point, you can use the option name intersections, which creates coordinates called intersection-1,
intersection-2, and so on at all intersections of the paths. Euclid assigns the names D and E to the paths
of the two circles (which happen to be the same names as the nodes themselves, but nodes and their paths
live in different “namespaces”).
C
D
B
A
E
\begin{tikzpicture}
\coordinate [label=left:$A$] (A) at (0,0);
\coordinate [label=right:$B$] (B) at (1.25,0.25);
\draw (A) -- (B);
\node (D) [name path=D,draw,circle through=(B),label=left:$D$] at (A) {};
\node (E) [name path=E,draw,circle through=(A),label=right:$E$] at (B) {};
% Name the coordinates, but do not draw anything:
\path [name intersections={of=D and E}];
\coordinate [label=above:$C$] (C) at (intersection-1);
\draw [red] (A) -- (C);
\draw [red] (B) -- (C);
\end{tikzpicture}
It turns out that this can be further shortened: The name intersections takes an optional argument
by, which lets you specify names for the coordinates and options for them. This creates more compact code.
Although Euclid does not need it for the current picture, it is just a small step to computing the bisection
of the line AB:
C
D
A
B
E
F
C0
61
\begin{tikzpicture}
\coordinate [label=left:$A$] (A) at (0,0);
\coordinate [label=right:$B$] (B) at (1.25,0.25);
\draw [name path=A--B] (A) -- (B);
\node (D) [name path=D,draw,circle through=(B),label=left:$D$] at (A) {};
\node (E) [name path=E,draw,circle through=(A),label=right:$E$] at (B) {};
\path [name intersections={of=D and E, by={[label=above:$C$]C, [label=below:$C’$]C’}}];
\draw [name path=C--C’,red] (C) -- (C’);
\path [name intersections={of=A--B and C--C’,by=F}];
\node [fill=red,inner sep=1pt,label=-45:$F$] at (F) {};
\end{tikzpicture}
4.1.5
The Complete Code
Back to Euclid’s code. He introduces a few macros to make life simpler, like a \A macro for typesetting a
blue A. He also uses the background layer for drawing the triangle behind everything at the end.
Proposition I
To construct an equilateral triangle on a given finite straight line.
Let AB be the given finite straight line. . . .
C
D
A
B
E
\begin{tikzpicture}[thick,help lines/.style={thin,draw=black!50}]
\def\A{\textcolor{input}{$A$}}
\def\B{\textcolor{input}{$B$}}
\def\C{\textcolor{output}{$C$}}
\def\D{$D$}
\def\E{$E$}
\colorlet{input}{blue!80!black}
\colorlet{triangle}{orange}
\colorlet{output}{red!70!black}
\coordinate [label=left:\A] (A) at ($ (0,0) + .1*(rand,rand) $);
\coordinate [label=right:\B] (B) at ($ (1.25,0.25) + .1*(rand,rand) $);
\draw [input] (A) -- (B);
\node [name path=D,help lines,draw,label=left:\D]
\node [name path=E,help lines,draw,label=right:\E]
(D) at (A) [circle through=(B)] {};
(E) at (B) [circle through=(A)] {};
\path [name intersections={of=D and E,by={[label=above:\C]C}}];
\draw [output] (A) -- (C) -- (B);
\foreach \point in {A,B,C}
\fill [black,opacity=.5] (\point) circle (2pt);
\begin{pgfonlayer}{background}
\fill[triangle!80] (A) -- (C) -- (B) -- cycle;
\end{pgfonlayer}
\node [below right, text width=10cm,align=justify] at (4,3) {
\small\textbf{Proposition I}\par
\emph{To construct an \textcolor{triangle}{equilateral triangle}
on a given \textcolor{input}{finite straight line}.}
\par\vskip1em
Let \A\B\ be the given \textcolor{input}{finite straight line}. \dots
};
\end{tikzpicture}
62
4.2
Book I, Proposition II
The second proposition in the Elements is the following:
Proposition II
To place a straight line equal to a given straight line with one
end at a given point.
K
C
H
D
B
A
G
L
F
E
4.2.1
Let A be the given point, and BC the given straight line. It is
required to place a straight line equal to the given straight line
BC with one end at the point A.
Join the straight line AB from the point A to the point B, and
construct the equilateral triangle DAB on it.
Produce the straight lines AE and BF in a straight line with DA
and DB. Describe the circle CGH with center B and radius BC,
and again, describe the circle GKL with center D and radius
DG.
Since the point B is the center of the circle CGH, therefore BC
equals BG. Again, since the point D is the center of the circle
GKL, therefore DL equals DG. And in these DA equals DB,
therefore the remainder AL equals the remainder BG. But BC
was also proved equal to BG, therefore each of the straight lines
AL and BC equals BG. And things which equal the same thing
also equal one another, therefore AL also equals BC.
Therefore the straight line AL equal to the given straight line
BC has been placed with one end at the given point A.
Using Partway Calculations for the Construction of D
Euclid’s construction starts with “referencing” Proposition I for the construction of the point D. Now, while
we could simply repeat the construction, it seems a bit bothersome that one has to draw all these circles
and do all these complicated constructions.
For this reason, Tik Z supports some simplifications. First, there is a simple syntax for computing a point
that is “partway” on a line from p to q: You place these two points in a coordinate calculation – remember,
they start with ($ and end with $) – and then combine them using !hparti!. A hparti of 0 refers to the
first coordinate, a hparti of 1 refers to the second coordinate, and a value in between refers to a point on
the line from p to q. Thus, the syntax is similar to the xcolor syntax for mixing colors.
Here is the computation of the point in the middle of the line AB:
A
B
X
\begin{tikzpicture}
\coordinate [label=left:$A$] (A) at (0,0);
\coordinate [label=right:$B$] (B) at (1.25,0.25);
\draw (A) -- (B);
\node [fill=red,inner sep=1pt,label=below:$X$] (X) at ($ (A)!.5!(B) $) {};
\end{tikzpicture}
The computation of the point D in Euclid’s second proposition is a bit more complicated. It can be
expressed as follows: Consider the line from X to B. Suppose we rotate this line around X for 90◦ and then
stretch it by a factor of sin(60◦ ) · 2. This yields the desired point D. We can do the stretching using the
partway modifier above, for the rotation we need a new modifier: the rotation modifier. The idea is that
the second coordinate in a partway computation can be prefixed by an angle. Then the partway point is
computed normally (as if no angle were given), but the resulting point is rotated by this angle around the
first point.
D
A
B
X
\begin{tikzpicture}
\coordinate [label=left:$A$] (A) at (0,0);
\coordinate [label=right:$B$] (B) at (1.25,0.25);
\draw (A) -- (B);
\node [fill=red,inner sep=1pt,label=below:$X$] (X) at ($ (A)!.5!(B) $) {};
\node [fill=red,inner sep=1pt,label=above:$D$] (D) at
($ (X) ! {sin(60)*2} ! 90:(B) $) {};
\draw (A) -- (D) -- (B);
\end{tikzpicture}
Finally, it is not necessary to explicitly name the point X. Rather, again like in the xcolor package, it
is possible to chain partway modifiers:
63
D
B
A
4.2.2
\begin{tikzpicture}
\coordinate [label=left:$A$] (A) at (0,0);
\coordinate [label=right:$B$] (B) at (1.25,0.25);
\draw (A) -- (B);
\node [fill=red,inner sep=1pt,label=above:$D$] (D) at
($ (A) ! .5 ! (B) ! {sin(60)*2} ! 90:(B) $) {};
\draw (A) -- (D) -- (B);
\end{tikzpicture}
Intersecting a Line and a Circle
The next step in the construction is to draw a circle around B through C, which is easy enough to do using
the circle through option. Extending the lines DA and DB can be done using partway calculations, but
this time with a part value outside the range [0, 1]:
C
H
D
B
A
F
E
\begin{tikzpicture}
\coordinate [label=left:$A$] (A) at (0,0);
\coordinate [label=right:$B$] (B) at (0.75,0.25);
\coordinate [label=above:$C$] (C) at (1,1.5);
\draw (A) -- (B) -- (C);
\coordinate [label=above:$D$] (D) at
($ (A) ! .5 ! (B) ! {sin(60)*2} ! 90:(B) $) {};
\node (H) [label=135:$H$,draw,circle through=(C)] at (B) {};
\draw (D) -- ($ (D) ! 3.5 ! (B) $) coordinate [label=below:$F$] (F);
\draw (D) -- ($ (D) ! 2.5 ! (A) $) coordinate [label=below:$E$] (E);
\end{tikzpicture}
We now face the problem of finding the point G, which is the intersection of the line BF and the circle H.
One way is to use yet another variant of the partway computation: Normally, a partway computation has the
form hpi!hfactor i!hqi, resulting in the point (1−hfactor i)hpi+hfactor ihqi. Alternatively, instead of hfactor i
you can also use a hdimensioni between the points. In this case, you get the point that is hdimensioni away
from hpi on the straight line to hqi.
We know that the point G is on the way from B to F . The distance is given by the radius of the circle H.
Here is the code for computing H:
\node (H) [label=135:$H$,draw,circle through=(C)] at (B) {};
\path let \p1 = ($ (B) - (C) $) in
coordinate [label=left:$G$] (G) at ($ (B) ! veclen(\x1,\y1) ! (F) $);
\fill[red,opacity=.5] (G) circle (2pt);
C
H
D
B
A
G
F
E
However, there is a simpler way: We can simply name the path of the circle and of the line in question
and then use name intersections to compute the intersections.
\node (H) [name path=H,label=135:$H$,draw,circle through=(C)] at (B) {};
\path [name path=B--F] (B) -- (F);
\path [name intersections={of=H and B--F,by={[label=left:$G$]G}}];
\fill[red,opacity=.5] (G) circle (2pt);
C
H
D
A
B
G
E
F
64
4.2.3
The Complete Code
K
C
H
D
B
A
G
L
F
E
\begin{tikzpicture}[thick,help lines/.style={thin,draw=black!50}]
\def\A{\textcolor{orange}{$A$}}
\def\B{\textcolor{input}{$B$}}
\def\C{\textcolor{input}{$C$}}
\def\D{$D$}
\def\E{$E$}
\def\F{$F$}
\def\G{$G$}
\def\H{$H$}
\def\K{$K$}
\def\L{\textcolor{output}{$L$}}
\colorlet{input}{blue!80!black}
\colorlet{output}{red!70!black}
\coordinate [label=left:\A] (A) at ($ (0,0) + .1*(rand,rand) $);
\coordinate [label=right:\B] (B) at ($ (1,0.2) + .1*(rand,rand) $);
\coordinate [label=above:\C] (C) at ($ (1,2) + .1*(rand,rand) $);
\draw [input] (B) -- (C);
\draw [help lines] (A) -- (B);
\coordinate [label=above:\D] (D) at ($ (A)!.5!(B) ! {sin(60)*2} ! 90:(B) $);
\draw [help lines] (D) -- ($ (D)!3.75!(A) $) coordinate [label=-135:\E] (E);
\draw [help lines] (D) -- ($ (D)!3.75!(B) $) coordinate [label=-45:\F] (F);
\node (H) at (B) [name path=H,help lines,circle through=(C),draw,label=135:\H] {};
\path [name path=B--F] (B) -- (F);
\path [name intersections={of=H and B--F,by={[label=right:\G]G}}];
\node (K) at (D) [name path=K,help lines,circle through=(G),draw,label=135:\K] {};
\path [name path=A--E] (A) -- (E);
\path [name intersections={of=K and A--E,by={[label=below:\L]L}}];
\draw [output] (A) -- (L);
\foreach \point in {A,B,C,D,G,L}
\fill [black,opacity=.5] (\point) circle (2pt);
% \node ...
\end{tikzpicture}
65
5
Tutorial: Diagrams as Simple Graphs
In this tutorial we have a look at how graphs and matrices can be used to typeset a diagram.
Ilka, who just got tenure for her professorship on Old and Lovable Programming Languages, has recently
dug up a technical report entitled The Programming Language Pascal in the dusty cellar of the library of
her university. Having been created in the good old times using pens and rules, it looks like this2 :
+
.
unsigned integer
digit
unsigned integer
E
-
For her next lecture, Ilka decides to redo this diagram, but this time perhaps a bit cleaner and perhaps
also bit “cooler.”
+
unsigned integer
.
digit
unsigned integer
E
-
Having read the previous tutorials, Ilka knows already how to set up the environment for her diagram,
namely using a tikzpicture environment. She wonders which libraries she will need. She decides that she
will postpone the decision and add the necessary libraries as needed as she constructs the picture.
5.1
Styling the Nodes
The bulk of this tutorial will be about arranging the nodes and connecting them using chains, but let us
start with setting up styles for the nodes.
There are two kinds of nodes in the diagram, namely what theoreticians like to call terminals and
nonterminals. For the terminals, Ilka decides to use a black color, which visually shows that “nothing needs
to be done about them.” The nonterminals, which still need to be “processed” further, get a bit of red mixed
in.
Ilka starts with the simpler nonterminals, as there are no rounded corners involved. Naturally, she sets
up a style:
unsigned integer
\begin{tikzpicture}[
nonterminal/.style={
% The shape:
rectangle,
% The size:
minimum size=6mm,
% The border:
very thick,
draw=red!50!black!50,
% 50% red and 50% black,
% and that mixed with 50% white
% The filling:
top color=white,
% a shading that is white at the top...
bottom color=red!50!black!20, % and something else at the bottom
% Font
font=\itshape
}]
\node [nonterminal] {unsigned integer};
\end{tikzpicture}
Ilka is pretty proud of the use of the minimum size option: As the name suggests, this option ensures
that the node is at least 6mm by 6mm, but it will expand in size as necessary to accommodate longer text.
By giving this option to all nodes, they will all have the same height of 6mm.
Styling the terminals is a bit more difficult because of the round corners. Ilka has several options how
she can achieve them. One way is to use the rounded corners option. It gets a dimension as parameter
and causes all corners to be replaced by little arcs with the given dimension as radius. By setting the radius
2 The shown diagram was not scanned, but rather typeset using Tik Z. The jittering lines were created using the randomsteps
decoration.
66
to 3mm, she will get exactly what she needs: circles, when the shapes are, indeed, exactly 6mm by 6mm
and otherwise half circles on the sides:
.
digit
E
\begin{tikzpicture}[node distance=5mm,
terminal/.style={
% The shape:
rectangle,minimum size=6mm,rounded corners=3mm,
% The rest
very thick,draw=black!50,
top color=white,bottom color=black!20,
font=\ttfamily}]
\node (dot)
[terminal]
{.};
\node (digit) [terminal,right=of dot]
{digit};
\node (E)
[terminal,right=of digit] {E};
\end{tikzpicture}
Another possibility is to use a shape that is specially made for typesetting rectangles with arcs on the
sides (she has to use the shapes.misc library to use it). This shape gives Ilka much more control over the
appearance. For instance, she could have an arc only on the left side, but she will not need this.
.
digit
E
\begin{tikzpicture}[node distance=5mm,
terminal/.style={
% The shape:
rounded rectangle,
minimum size=6mm,
% The rest
very thick,draw=black!50,
top color=white,bottom color=black!20,
font=\ttfamily}]
\node (dot)
[terminal]
{.};
\node (digit) [terminal,right=of dot]
{digit};
\node (E)
[terminal,right=of digit] {E};
\end{tikzpicture}
At this point, she notices a problem. The baseline of the text in the nodes is not aligned:
.
digit
\begin{tikzpicture}[node distance=5mm]
\node (dot)
[terminal]
{.};
\node (digit) [terminal,right=of dot]
{digit};
\node (E)
[terminal,right=of digit] {E};
E
\draw [help lines] let \p1 = (dot.base),
\p2 = (digit.base),
\p3 = (E.base)
in (-.5,\y1) -- (3.5,\y1)
(-.5,\y2) -- (3.5,\y2)
(-.5,\y3) -- (3.5,\y3);
\end{tikzpicture}
(Ilka has moved the style definition to the preamble by saying \tikzset{terminal/.style=...}, so that
she can use it in all pictures.)
For the digit and the E the difference in the baselines is almost imperceptible, but for the dot the
problem is quite severe: It looks more like a multiplication dot than a period.
Ilka toys with the idea of using the base right=of... option rather than right=of... to align the
nodes in such a way that the baselines are all on the same line (the base right option places a node right
of something so that the baseline is right of the baseline of the other object). However, this does not have
the desired effect:
.
digit
E
\begin{tikzpicture}[node distance=5mm]
\node (dot)
[terminal]
{.};
\node (digit) [terminal,base right=of dot]
{digit};
\node (E)
[terminal,base right=of digit] {E};
\end{tikzpicture}
The nodes suddenly “dance around”! There is no hope of changing the position of text inside a node using
anchors. Instead, Ilka must use a trick: The problem of mismatching baselines is caused by the fact that .
and digit and E all have different heights and depth. If they all had the same, they would all be positioned
vertically in the same manner. So, all Ilka needs to do is to use the text height and text depth options
to explicitly specify a height and depth for the nodes.
67
.
5.2
digit
E
\begin{tikzpicture}[node distance=5mm,
text height=1.5ex,text depth=.25ex]
\node (dot)
[terminal]
{.};
\node (digit) [terminal,right=of dot]
{digit};
\node (E)
[terminal,right=of digit] {E};
\end{tikzpicture}
Aligning the Nodes Using Positioning Options
Ilka now has the “styling” of the nodes ready. The next problem is to place them in the right places.
There are several ways to do this. The most straightforward is to simply explicitly place the nodes at
certain coordinates “calculated by hand.” For very simple graphics this is perfectly alright, but it has several
disadvantages:
1. For more difficult graphics, the calculation may become complicated.
2. Changing the text of the nodes may make it necessary to recalculate the coordinates.
3. The source code of the graphic is not very clear since the relationships between the positions of the
nodes are not made explicit.
For these reasons, Ilka decides to try out different ways of arranging the nodes on the page.
The first method is the use of positioning options. To use them, you need to load the positioning
library. This gives you access to advanced implementations of options like above or left, since you can
now say above=of some node in order to place a node above of some node, with the borders separated by
node distance.
Ilka can use this to draw the place the nodes in a long row:
+
unsigned integer
.
digit
unsigned integer
E
-
\begin{tikzpicture}[node distance=5mm and 5mm]
\node (ui1)
[nonterminal]
\node (dot)
[terminal,right=of ui1]
\node (digit) [terminal,right=of dot]
\node (E)
[terminal,right=of digit]
\node (plus) [terminal,above right=of E]
\node (minus) [terminal,below right=of E]
\node (ui2)
[nonterminal,below right=of plus]
\end{tikzpicture}
{unsigned integer};
{.};
{digit};
{E};
{+};
{-};
{unsigned integer};
For the plus and minus nodes, Ilka is a bit startled by their placements. Shouldn’t they be more to the
right? The reason they are placed in that manner is the following: The north east anchor of the E node
lies at the “upper start of the right arc,” which, a bit unfortunately in this case, happens to be the top of the
node. Likewise, the south west anchor of the + node is actually at its bottom and, indeed, the horizontal
and vertical distances between the top of the E node and the bottom of the + node are both 5mm.
There are several ways of fixing this problem. The easiest way is to simply add a little bit of horizontal
shift by hand:
+
unsigned integer
E
-
68
\begin{tikzpicture}[node distance=5mm and 5mm]
\node (E)
[terminal]
\node (plus) [terminal,above right=of E,xshift=5mm]
\node (minus) [terminal,below right=of E,xshift=5mm]
\node (ui2)
[nonterminal,below right=of plus,xshift=5mm]
\end{tikzpicture}
{E};
{+};
{-};
{unsigned integer};
A second way is to revert back to the idea of using a normal rectangle for the terminals, but with rounded
corners. Since corner rounding does not affect anchors, she gets the following result:
+
unsigned integer
E
-
\begin{tikzpicture}[node distance=5mm and 5mm,terminal/.append style={rectangle,rounded corners=3mm}]
\node (E)
[terminal]
{E};
\node (plus) [terminal,above right=of E]
{+};
\node (minus) [terminal,below right=of E]
{-};
\node (ui2)
[nonterminal,below right=of plus] {unsigned integer};
\end{tikzpicture}
A third way is to use matrices, which we will do later.
Now that the nodes have been placed, Ilka needs to add connections. Here, some connections are more
difficult than others. Consider for instance the “repeat” line around the digit. One way of describing this
line is to say “it starts a little to the right of digit than goes down and then goes to the left and finally
ends at a point a little to the left of digit.” Ilka can put this into code as follows:
.
digit
E
\begin{tikzpicture}[node distance=5mm and 5mm]
\node (dot)
[terminal]
\node (digit) [terminal,right=of dot]
\node (E)
[terminal,right=of digit]
\path (dot)
edge[->] (digit)
(digit) edge[->] (E);
{.};
{digit};
{E};
% simple edges
\draw [->]
% start right of digit.east, that is, at the point that is the
% linear combination of digit.east and the vector (2mm,0pt). We
% use the ($ ... $) notation for computing linear combinations
($ (digit.east) + (2mm,0) $)
% Now go down
-- ++(0,-.5)
% And back to the left of digit.west
-| ($ (digit.west) - (2mm,0) $);
\end{tikzpicture}
Since Ilka needs this “go up/down then horizontally and then up/down to a target” several times, it seems
sensible to define a special to-path for this. Whenever the edge command is used, it simply adds the current
value of to path to the path. So, Ilka can set up a style that contains the correct path:
.
digit
E
\begin{tikzpicture}[node distance=5mm and 5mm,
skip loop/.style={to path={-- ++(0,-.5) -| (\tikztotarget)}}]
\node (dot)
[terminal]
{.};
\node (digit) [terminal,right=of dot]
{digit};
\node (E)
[terminal,right=of digit]
{E};
\path (dot)
edge[->]
(digit) % simple edges
(digit) edge[->]
(E)
($ (digit.east) + (2mm,0) $)
edge[->,skip loop] ($ (digit.west) - (2mm,0) $);
\end{tikzpicture}
Ilka can even go a step further and make her skip look style parameterized. For this, the skip loop’s
vertical offset is passed as parameter #1. Also, in the following code Ilka specifies the start and targets
differently, namely as the positions that are “in the middle between the nodes.”
69
.
digit
\begin{tikzpicture}[node distance=5mm and 5mm,
skip loop/.style={to path={-- ++(0,#1) -| (\tikztotarget)}}]
\node (dot)
[terminal]
{.};
\node (digit) [terminal,right=of dot]
{digit};
\node (E)
[terminal,right=of digit]
{E};
E
\path (dot)
edge[->]
(digit) % simple edges
(digit) edge[->]
(E)
($ (digit.east)!.5!(E.west) $)
edge[->,skip loop=-5mm] ($ (digit.west)!.5!(dot.east) $);
\end{tikzpicture}
5.3
Aligning the Nodes Using Matrices
Ilka is still bothered a bit by the placement of the plus and minus nodes. Somehow, having to add an explicit
xshift seems too much like cheating.
A perhaps better way of positioning the nodes is to use a matrix. In Tik Z matrices can be used to align
quite arbitrary graphical objects in rows and columns. The syntax is very similar to the use of arrays and
tables in TEX (indeed, internally TEX tables are used, but a lot of stuff is going on additionally).
In Ilka’s graphic, there will be three rows: One row containing only the plus node, one row containing
the main nodes and one row containing only the minus node.
+
unsigned integer
.
digit
unsigned integer
E
-
\begin{tikzpicture}
\matrix[row sep=1mm,column sep=5mm] {
% First row:
& & & & \node [terminal] {+}; & \\
% Second row:
\node [nonterminal] {unsigned integer};
\node [terminal]
{.};
\node [terminal]
{digit};
\node [terminal]
{E};
&
&
&
&
&
\node [nonterminal] {unsigned integer}; \\
% Third row:
& & & & \node [terminal] {-}; & \\
};
\end{tikzpicture}
That was easy! By toying around with the row and columns separations, Ilka can achieve all sorts of
pleasing arrangements of the nodes.
Ilka now faces the same connecting problem as before. This time, she has an idea: She adds small
nodes (they will be turned into coordinates later on and be invisible) at all the places where she would like
connections to start and end.
+
unsigned integer
.
digit
unsigned integer
E
-
70
\begin{tikzpicture}[point/.style={circle,inner sep=0pt,minimum size=2pt,fill=red},
skip loop/.style={to path={-- ++(0,#1) -| (\tikztotarget)}}]
\matrix[row sep=1mm,column sep=2mm] {
% First row:
& & & & & & & & & & & \node (plus) [terminal] {+};\\
% Second row:
\node (p1) [point] {}; &
\node (ui1)
[nonterminal] {unsigned integer}; &
\node (p2) [point] {}; &
\node (dot)
[terminal]
{.};
&
\node (p3) [point] {}; &
\node (digit) [terminal]
{digit};
&
\node (p4) [point] {}; &
\node (p5)
[point] {};
&
\node (p6) [point] {}; &
\node (e)
[terminal]
{E};
&
\node (p7) [point] {}; &
&
\node (p8) [point] {}; &
\node (ui2)
[nonterminal] {unsigned integer}; &
\node (p9) [point] {}; &
\node (p10)
[point]
{};\\
% Third row:
& & & & & & & & & & & \node (minus)[terminal] {-};\\
};
\path (p4) edge [->,skip loop=-5mm] (p3)
(p2) edge [->,skip loop=5mm] (p6);
\end{tikzpicture}
Now, it’s only a small step to add all the missing edges.
5.4
The Diagram as a Graph
Matrices allow Ilka to align the nodes nicely, but the connections are not quite perfect. The problem is that
the code does not really reflect the paths that underlie the diagram. For this, it seems natural enough to
Ilka to use the graph library since, after all, connecting nodes by edges is exactly what happens in a graph.
The graph library can both be used to connect nodes that have already been created, but it can also be
used to create nodes “on the fly” and these processes can also be mixed.
5.4.1
Connecting Already Positioned Nodes
Ilka has already a fine method for positioning her nodes (using a matrix), so all that she needs is an easy
way of specifying the edges. For this, she uses the \graph command (which is actually just a shorthand for
\path graph). It allows her to write down edges between them in a simple way (the macro \matrixcontent
contains exactly the matrix content from the previous example; no need to repeat it here):
+
unsigned integer
.
digit
unsigned integer
E
-
\begin{tikzpicture}[skip loop/.style={to path={-- ++(0,#1) -| (\tikztotarget)}},
hv path/.style={to path={-| (\tikztotarget)}},
vh path/.style={to path={|- (\tikztotarget)}}]
\matrix[row sep=1mm,column sep=2mm] { \matrixcontent };
\graph {
(p1) -> (ui1) -- (p2) -> (dot) -- (p3) -> (digit) -- (p4)
-- (p5) -- (p6) -> (e) -- (p7) -- (p8) -> (ui2) -- (p9) -> (p10);
(p4) ->[skip loop=-5mm] (p3);
(p2) ->[skip loop=5mm]
(p5);
(p6) ->[skip loop=-11mm] (p9);
(p7) ->[vh path]
(plus) -> [hv path] (p8);
(p7) ->[vh path]
(minus) -> [hv path] (p8);
};
\end{tikzpicture}
This is already pretty near to the desired result, just a few “finishing touches” are needed to style the
edges more nicely.
However, Ilka does not have the feeling that the graph command is all that hot in the example. It
certainly does cut down on the number of characters she has to write, but the overall graph structure is not
that much clear – it is still mainly a list of paths through the graph. It would be nice to specify that, say,
71
there the path from (p7) sort of splits to (plus) and (minus) and then merges once more at (p8). Also,
all these parentheses are bit hard to type.
It turns out that edges from a node to a whole group of nodes are quite easy to specify, as shown in
the next example. Additionally, by using the use existing nodes option, Ilka can also leave out all the
parentheses (again, some options have been moved outside to keep the examples shorter):
+
unsigned integer
.
digit
unsigned integer
E
-
\begin{tikzpicture}[,>=stealth’,thick,black!50,text=black,
every new ->/.style={shorten >=1pt},
graphs/every graph/.style={edges=rounded corners}]
\matrix[column sep=4mm] { \matrixcontent };
\graph [use existing nodes] {
p1 -> ui1 -- p2 -> dot -- p3 -> digit -- p4 -- p5
p4 ->[skip loop=-5mm] p3;
p2 ->[skip loop=5mm]
p5;
p6 ->[skip loop=-11mm] p9;
p7 ->[vh path] { plus, minus } -> [hv path] p8;
};
\end{tikzpicture}
5.4.2
-- p6 -> e -- p7 -- p8 -> ui2 -- p9 -> p10;
Creating Nodes Using the Graph Command
Ilka has heard that the graph command is also supposed to make it easy to create nodes, not only to connect
them. This is, indeed, correct: When the use existing node option is not used and when a node name
is not surrounded by parentheses, then Tik Z will actually create a node whose name and text is the node
name:
unsigned integer
d
digit
E
\tikz \graph [grow right=2cm] { unsigned integer -> d -> digit -> E };
Not quite perfect, but we are getting somewhere. First, let us change the positioning algorithm by saying
grow right sep, which causes new nodes to be placed to the right of the previous nodes with a certain
fixed separation (1em by default). Second, we add some options to make the node “look nice”. Third, note
the funny d node above: Ilka tried writing just . there first, but got some error messages. The reason is
that a node cannot be called . in Tik Z, so she had to choose a different name – which is not good, since
she wants a dot to be shown! The trick is to put the dot in quotation marks, this allows you to use “quite
arbitrary text” as a node name:
unsigned integer
.
digit
E
\tikz \graph [grow right sep] {
unsigned integer[nonterminal] -> "."[terminal] -> digit[terminal] -> E[terminal]
};
Now comes the fork to the plus and minus signs. Here, Ilka can use the grouping mechanism of the graph
command to create a split:
unsigned integer
.
digit
E
+
unsigned integer
-
72
\tikz \graph [grow right sep] {
unsigned integer [nonterminal] ->
"."
[terminal] ->
digit
[terminal] ->
E
[terminal] ->
{
"+"
[terminal],
""
[coordinate],
"-"
[terminal]
} ->
ui2/unsigned integer [nonterminal]
};
Let us see, what is happening here. We want two unsigned integer nodes, but if we just were to use
this text twice, then Tik Z would have noticed that the same name was used already in the current graph
and, being smart (actually too smart in this case), would have created an edge back to the already-created
node. Thus, a fresh name is needed here. However, Ilka also cannot just write unsigned integer2, because
she wants the original text to be shown, after all! The trick is to use a slash inside the node name: In order
to “render” the node, the text following the slash is used instead of the node name, which is the text before
the slash. Alternatively, the as option can be used, which also allows you to specify how a node should be
rendered.
It turns out that Ilka does not need to invent a name like ui2 for a node that she will not reference again
anyway. In this case, she can just leave out the name (write nothing before /), which always stands for a
“fresh, anonymous” node name.
Next, Ilka needs to add some coordinates in between of some nodes where the back-loops should got and
she needs to shift the nodes a bit:
+
unsigned integer
.
digit
unsigned integer
E
-
\begin{tikzpicture}[>=stealth’, thick, black!50, text=black,
every new ->/.style={shorten >=1pt},
graphs/every graph/.style={edges=rounded corners}]
\graph [grow right sep, branch down=7mm] {
/
[coordinate] ->
unsigned integer
[nonterminal] -p1
[coordinate] ->
"."
[terminal] -p2
[coordinate] ->
digit
[terminal] -p3
[coordinate] -p4
[coordinate] -p5
[coordinate] ->
E
[terminal] -q1
[coordinate] ->[vh path]
{ [nodes={yshift=7mm}]
"+"
[terminal],
q2/
[coordinate],
"-"
[terminal]
} -> [hv path]
q3
[coordinate] -/unsigned integer [nonterminal] -p6
[coordinate] ->
/
[coordinate];
p1 ->[skip loop=5mm]
p4;
p3 ->[skip loop=-5mm] p2;
p5 ->[skip loop=-11mm] p6;
};
\end{tikzpicture}
All that remains to be done is to somehow get rid of the strange curves between the E and the unsigned
integer. They are caused by Tik Z’s attempt at creating an edge that first goes vertical and then horizontal
but is actually just horizontal. Additionally, the edge should not really be pointed; but it seems difficult to
get rid of this since the other edges from q1, namely to plus and minus should be pointed.
73
It turns out that there is a nice way of solving this problem: You can specify that a graph is simple.
This means that there can be at most one edge between any two nodes. Now, if you specify an edge twice,
the options of the second specification “win.” Thus, by adding two more lines that “correct” these edges, we
get the final diagram with its complete code:
+
unsigned integer
.
digit
unsigned integer
E
-
\tikz [>=stealth’, black!50, text=black, thick,
every new ->/.style
= {shorten >=1pt},
graphs/every graph/.style
= {edges=rounded corners},
skip loop/.style
= {to path={-- ++(0,#1) -| (\tikztotarget)}},
hv path/.style
= {to path={-| (\tikztotarget)}},
vh path/.style
= {to path={|- (\tikztotarget)}},
nonterminal/.style
= {
rectangle, minimum size=6mm, very thick, draw=red!50!black!50, top color=white,
bottom color=red!50!black!20, font=\itshape, text height=1.5ex,text depth=.25ex},
terminal/.style
= {
rounded rectangle, minimum size=6mm, very thick, draw=black!50, top color=white,
bottom color=black!20, font=\ttfamily, text height=1.5ex, text depth=.25ex},
shape
= coordinate
]
\graph [grow right sep, branch down=7mm, simple] {
/ -> unsigned integer[nonterminal] -- p1 -> "." [terminal] -- p2 -> digit[terminal] -p3 -- p4 -- p5 -> E[terminal] -- q1 ->[vh path]
{[nodes={yshift=7mm}]
"+"[terminal], q2, "-"[terminal]
} -> [hv path]
q3 -- /unsigned integer [nonterminal] -- p6 -> /;
p1 ->[skip loop=5mm]
p4;
p3 ->[skip loop=-5mm] p2;
p5 ->[skip loop=-11mm] p6;
q1 -- q2 -- q3;
% make these edges plain
};
74
6
Tutorial: A Lecture Map for Johannes
In this tutorial we explore the tree and mind map mechanisms of Tik Z.
Johannes is quite excited: For the first time he will be teaching a course all by himself during the
upcoming semester! Unfortunately, the course is not on his favorite subject, which is of course Theoretical
Immunology, but on Complexity Theory, but as a young academic Johannes is not likely to complain too
loudly. In order to help the students get a general overview of what is going to happen during the course
as a whole, he intends to draw some kind of tree or graph containing the basic concepts. He got this idea
from his old professor who seems to be using these “lecture maps” with some success. Independently of the
success of these maps, Johannes thinks they look quite neat.
6.1
Problem Statement
Johannes wishes to create a lecture map with the following features:
1. It should contain a tree or graph depicting the main concepts.
2. It should somehow visualize the different lectures that will be taught. Note that the lectures are not
necessarily the same as the concepts since the graph may contain more concepts than will be addressed
in lectures and some concepts may be addressed during more than one lecture.
3. The map should also contain a calendar showing when the individual lectures will be given.
4. The aesthetical reasons, the whole map should have a visually nice and information-rich background.
As always, Johannes will have to include the right libraries and set up the environment. Johannes is going
to use the mindmap library and since he wishes to show a calendar, he will also need the calendar library.
In order to put something on a background layer, it seems like a good idea to also include the backgrounds
library.
6.2
Introduction to Trees
The first choice Johannes must make is whether he will organize the concepts as a tree, with root concepts
and concept branches and leaf concepts, or as a general graph. The tree implicitly organizes the concepts,
while a graph is more flexible. Johannes decides to compromise: Basically, the concepts will be organized
as a tree. However, he will selectively add connections between concepts that are related, but which appear
on different levels or branches of the tree.
Johannes starts with a tree-like list of concepts that he feels are important in Computational Complexity:
• Computational Problems
–
–
–
–
Problem Measures
Problem Aspects
Problem Domains
Key Problems
• Computational Models
–
–
–
–
–
–
Turing Machines
Random-Access Machines
Circuits
Binary Decision Diagrams
Oracle Machines
Programming in Logic
• Measuring Complexity
–
–
–
–
Complexity Measures
Classifying Complexity
Comparing Complexity
Describing Complexity
• Solving Problems
75
–
–
–
–
–
–
Exact Algorithms
Randomization
Fixed-Parameter Algorithms
Parallel Computation
Partial Solutions
Approximation
Johannes will surely need to modify this list later on, but it looks good as a first approximation. He
will also need to add a number of subtopics (like lots of complexity classes under the topic “classifying
complexity”), but he will do this as he constructs the map.
Turning the list of topics into a Tik Z-tree is easy, in principle. The basic idea is that a node can have
children, which in turn can have children of their own, and so on. To add a child to a node, Johannes can
simply write child {hnodei} right after a node. The hnodei should, in turn, be the code for creating a
node. To add another node, Johannes can use child once more, and so on. Johannes is eager to try out
this construct and writes down the following:
Computational Complexity
Computational
Computational
Measuring
Problems
Models
Solving
Complexity
Problems
Turing
Problem
Machines
Complexity
Exact
Binary
Aspects
Classifying
Algorithms
Fixed-Parameter
Key
Decision
Comparing
Measures
Problems
Complexity
Describing
Programming
Parallel
Diagrams
Complexity
Algorithms
Computation
Complexity
in Approximation
Logic
Problem
Random-Access
Measures
Problem
Circuits
Machines
Randomization
Domains
Oracle
Machines
Partial
Solutions
\tikz
\node {Computational Complexity} % root
child { node {Computational Problems}
child { node {Problem Measures} }
child { node {Problem Aspects} }
child { node {Problem Domains} }
child { node {Key Problems} }
}
child { node {Computational Models}
child { node {Turing Machines} }
child { node {Random-Access Machines} }
child { node {Circuits} }
child { node {Binary Decision Diagrams} }
child { node {Oracle Machines} }
child { node {Programming in Logic} }
}
child { node {Measuring Complexity}
child { node {Complexity Measures} }
child { node {Classifying Complexity} }
child { node {Comparing Complexity} }
child { node {Describing Complexity} }
}
child { node {Solving Problems}
child { node {Exact Algorithms} }
child { node {Randomization} }
child { node {Fixed-Parameter Algorithms} }
child { node {Parallel Computation} }
child { node {Partial Solutions} }
child { node {Approximation} }
};
Well, that did not quite work out as expected (although, what, exactly, did one expect?). There are two
problems:
1. The overlap of the nodes is due to the fact that Tik Z is not particularly smart when it comes to placing
child nodes. Even though it is possible to configure Tik Z to use rather clever placement methods, Tik Z
has no way of taking the actual size of the child nodes into account. This may seem strange but the
reason is that the child nodes are rendered and placed one at a time, so the size of the last node is not
known when the first node is being processed. In essence, you have to specify appropriate level and
sibling node spacings “by hand.”
2. The standard computer-science-top-down rendering of a tree is rather ill-suited to visualizing the
concepts. It would be better to either rotate the map by ninety degrees or, even better, to use some
sort of circular arrangement.
76
Johannes redraws the tree, but this time with some more appropriate options set, which he found more
or less by trial-and-error:
Solving Problems
Approximation
Partial Solutions
Parallel Computation
Fixed-Parameter Algorithms
Randomization
Exact Algorithms
Measuring Complexity
Describing Complexity
Comparing Complexity
Classifying Complexity
Complexity Measures
Computational Models
Programming in Logic
Oracle Machines
Binary Decision Diagrams
Circuits
Random-Access Machines
Turing Machines
Computational Problems
Key Problems
Problem Domains
Problem Aspects
Problem Measures
Computational Complexity
\tikz [font=\footnotesize,
grow=right, level 1/.style={sibling distance=6em},
level 2/.style={sibling distance=1em}, level distance=5cm]
\node {Computational Complexity} % root
child { node {Computational Problems}
child { node {Problem Measures} }
child { node {Problem Aspects} }
... % as before
Still not quite what Johannes had in mind, but he is getting somewhere.
For configuring the tree, two parameters are of particular importance: The level distance tells Tik Z
the distance between (the centers of) the nodes on adjacent levels or layers of a tree. The sibling distance
is, as the name suggests, the distance between (the centers of) siblings of the tree.
You can globally set these parameters for a tree by simply setting them somewhere before the tree starts,
but you will typically wish them to be different for different levels of the tree. In this case, you should set
styles like level 1 or level 2. For the first level of the tree, the level 1 style is used, for the second
level the level 2 style, and so on. You can also set the sibling and level distances only for certain nodes
by passing these options to the child command as options. (Note that the options of a node command are
local to the node and have no effect on the children. Also note that it is possible to specify options that
do have an effect on the children. Finally note that specifying options for children “at the right place” is an
arcane art and you should peruse Section 21.4 on a rainy Sunday afternoon, if you are really interested.)
The grow key is used to configure the direction in which a tree grows. You can change growth direction
“in the middle of a tree” simply by changing this key for a single child or a whole level. By including the
trees library you also get access to additional growth strategies such as a “circular” growth:
77
Describing
Complexity Comparing
Complexity
Fixed- Randomization
Exact
Parameter
Algorithms
Algorithms
Parallel
Computation
Partial
Solutions
Classifying
Complexity
Measuring
Complexity
Solving Problems
Approximation
Computational
Complexity
Computational
Problems
Problem
Measures
Complexity
Measures
Programming
in Logic
Computational
Models
Binary
Decision
Diagrams
Problem
Aspects
Problem
Domains
Oracle
Machines
Key Problems
Turing
Machines
RandomAccess
Machines
Circuits
\tikz [text width=2.7cm, align=flush center,
grow cyclic,
level 1/.style={level distance=2.5cm,sibling angle=90},
level 2/.style={text width=2cm, font=\footnotesize, level distance=3cm,sibling angle=30}]
\node[font=\bfseries] {Computational Complexity} % root
child { node {Computational Problems}
child { node {Problem Measures} }
child { node {Problem Aspects} }
... % as before
Johannes is pleased to learn that he can access and manipulate the nodes of the tree like any normal
node. In particular, he can name them using the name= option or the (hnamei) notation and he can use any
available shape or style for the trees nodes. He can connect trees later on using the normal \draw (some
node) --(another node); syntax. In essence, the child command just computes an appropriate position
for a node and adds a line from the child to the parent node.
6.3
Creating the Lecture Map
Johannes now has a first possible layout for his lecture map. The next step is to make it “look nicer.” For
this, the mindmap library is helpful since it makes a number of styles available that will make a tree look like
a nice “mind map” or “concept map.”
The first step is to include the mindmap library, which Johannes already did. Next, he must add one of the
following options to a scope that will contain the lecture map: mindmap or large mindmap or huge mindmap.
These options all have the same effect, except that for a large mindmap the predefined font size and node
sizes are somewhat larger than for a standard mindmap and for a huge mindmap they are even larger. So, a
large mindmap does not necessarily need to have a lot of concepts, but it will need a lot of paper.
The second step is to add the concept option to every node that will, indeed, be a concept of the mindmap.
The idea is that some nodes of a tree will be real concepts, while other nodes might just be “simple children.”
Typically, this is not the case, so you might consider saying every node/.style=concept.
The third step is to set up the sibling angle (rather than a sibling distance) to specify the angle between
sibling concepts.
78
FixedParameter
Algorithms
Describing
Complexity
Randomization
Parallel
Computation
Comparing
Complexity
Classifying
Complexity
Exact
Algorithms
Measuring
Complexity
Solving
Problems
Complexity
Measures
Partial
Solutions
Approximation
Computational
Complexity
Programming
in Logic
Problem
Measures
Oracle
Machines
Computational
Problems
Problem
Aspects
Computational
Models
Binary
Decision
Diagrams
Turing
Machines
Problem
Domains
Key
Problems
RandomAccess
Machines
Circuits
\tikz [mindmap, every node/.style=concept, concept color=black!20,
grow cyclic,
level 1/.append style={level distance=4.5cm,sibling angle=90},
level 2/.append style={level distance=3cm,sibling angle=45}]
\node [root concept] {Computational Complexity} % root
child { node {Computational Problems}
child { node {Problem Measures} }
child { node {Problem Aspects} }
... % as before
When Johannes typesets the above map, TEX (rightfully) starts complaining about several overfull boxes
and, indeed, words like “Randomization” stretch out beyond the circle of the concept. This seems a bit
mysterious at first sight: Why does TEX not hyphenate the word? The reason is that TEX will never
hyphenate the first word of a paragraph because it starts looking for “hyphenatable” letters only after a
so-called glue. In order to have TEX hyphenate these single words, Johannes must use a bit of evil trickery:
He inserts a \hskip0pt before the word. This has no effect except for inserting an (invisible) glue before
the word and, thereby, allowing TEX to hyphenate the first word also. Since Johannes does not want to add
\hskip0pt inside each node, he uses the execute at begin node option to make Tik Z insert this text with
every node.
79
FixedParameter
Algorithms
Randomization
Parallel
Computation
Solving
Problems
Partial
Solutions
\begin{tikzpicture}
[mindmap,
Describing
Comparing
every node/.style={concept,
execute at begin node=\hskip0pt},
ComComconcept color=black!20,
plexity
grow cyclic,plexity
level 1/.append style={level distance=4.5cm,sibling angle=90},
level 2/.append style={level distance=3cm,sibling angle=45}]
Classifying
\clip (-1,2) rectangle ++ (-4,5);
Exact
Com\node [root concept] {Computational Complexity}
% root
Algorithms
child { node {Computational Problems}plexity
child { node {Problem Measures} }
Measuring
child { node {Problem Aspects} }
Complexity
... % as before
\end{tikzpicture}
Complexity
Measures
In the above example a clipping was used to show only part of the lecture map, in order to save space.
The same will be done in the following examples, we return to the complete lecture map at the end of this
Approxtutorial.
imation
Computational
Johannes is now eager
to colorize the map. The idea is to use different colors for different parts of the
ProgramComplexity
map. He can then, during his
lectures, talk about the “green”
orinthe “red” topics. This will make it easier for
ming
his students to locate the topic he is talking about on the Logic
map. Since “computational problems” somehow
sounds “problematic,” Johannes chooses red for them, while he picks green for the “solving problems.” The
topics “measuring complexity” and “computational models” get more neutral colors; Johannes picks orange
Problem and blue.
Oracle
Measures
Machines
To set the colors, Johannes must use the concept color option, rather than just, say, node [fill=red].
CompuSetting just
the fill color to red would, indeed, make the node red, but it would just make the node red
Computatational
and not the
bar connecting the concept to its parent
and also not its children. By comparison, the special
tional Models
conceptProblems
color option will not only set the color of the node and its children, but it will also (magically)
Binary changes to the color of a child
Describing shadings
Comparing
so that
the color of a parent concept smoothly
Turing
andom-Problem create appropriate
Decision
ComComAspects
Machines
concept. plexity
zation
Diagrams
plexity
For the root concept Johannes decides to do something special: He sets the concept color to black, sets
the line width to a large value, and sets the fill color to white. The effect of this is that the root concept
Classifying
Randombe encircled with
Exactwill
Problem
Key a thick black line and the children are connected to the central concept via bars.
Key
roblems
Algorithms
Domains
Computational
Complexity
Turing
Machines
Com- Access
Circuits
plexity Machines
\begin{tikzpicture}
[mindmap,
Measuring
every node/.style={concept, execute at begin node=\hskip0pt},
Complexity
root concept/.append style={
concept color=black, fill=white, line width=1ex, text=black},
Comtext=white,
grow plexity
cyclic,
Measures
level
1/.append style={level distance=4.5cm,sibling angle=90},
level 2/.append style={level distance=3cm,sibling angle=45}]
\clip (0,-1) rectangle ++(4,5);
\node [root concept] {Computational Complexity} % root
child [concept color=red] { node {Computational Problems}
Program- child { node {Problem Measures} }
ming in
... % as before
Logic }
child [concept color=blue] { node {Computational Models}
child { node {Turing Machines} }
...
% as before
Oracle
} Machines
child [concept color=orange] { node {Measuring Complexity}
child { node {Complexity Measures} }
Computa... % as before
tional Models
}
child [concept color=green!50!black] { node {Solving Problems}
Binary
child { node {Exact Algorithms} }
Decision
... % as before
Diagrams
};
\end{tikzpicture}
Problems
RandomJohannes
adds three finishing touches: First, he changes the font of the main concepts to small caps. SecAccess
Circuits
ond, he decides
that some concepts should be “faded,” namely those that are important in principle and belong
Machines
on the map, but which he will not talk about in his lecture. To achieve this, Johannes defines four styles, one
for each of the four main branches. These styles (a) set up the correct concept color for the whole branch and
80
(b) define the faded style appropriately for this branch. Third, he adds a circular drop shadow, defined
in the shadows library, to the concepts, just to make things look a bit more fancy.
FixedParameter
Algorithms
Describing
Complexity
Randomization
Parallel
Computation
Comparing
Complexity
Exact
Algorithms
Classifying
Complexity
Measuring
Complexity
Solving
Problems
Partial
Solutions
Complexity
Measures
Approximation
Computational
Complexity
Programming in
Logic
Problem
Measures
Oracle
Machines
Computational
Problems
Problem
Aspects
Computational
Models
Binary
Decision
Diagrams
Turing
Machines
Problem
Domains
RandomAccess
Machines
Key
Problems
Circuits
\begin{tikzpicture}[mindmap]
\begin{scope}[
every node/.style={concept, circular drop shadow,execute at begin node=\hskip0pt},
root concept/.append style={
concept color=black, fill=white, line width=1ex, text=black, font=\large\scshape},
text=white,
computational problems/.style={concept color=red,faded/.style={concept color=red!50}},
computational models/.style={concept color=blue,faded/.style={concept color=blue!50}},
measuring complexity/.style={concept color=orange,faded/.style={concept color=orange!50}},
solving problems/.style={concept color=green!50!black,faded/.style={concept color=green!50!black!50}},
grow cyclic,
level 1/.append style={level distance=4.5cm,sibling angle=90,font=\scshape},
level 2/.append style={level distance=3cm,sibling angle=45,font=\scriptsize}]
\node [root concept] {Computational Complexity} % root
child [computational problems] { node {Computational Problems}
child
{ node {Problem Measures} }
child
{ node {Problem Aspects} }
child [faded] { node {Problem Domains} }
child
{ node {Key Problems} }
}
child [computational models] { node {Computational Models}
child
{ node {Turing Machines} }
child [faded] { node {Random-Access Machines} }
...
\end{scope}
\end{tikzpicture}
81
6.4
Adding the Lecture Annotations
Johannes will give about a dozen lectures during the course “computational complexity.” For each lecture
he has compiled a (short) list of learning targets that state what knowledge and qualifications his students
should acquire during this particular lecture (note that learning targets are not the same as the contents of
a lecture). For each lecture he intends to put a little rectangle on the map containing these learning targets
and the name of the lecture, each time somewhere near the topic of the lecture. Such “little rectangles” are
called “annotations” by the mindmap library.
In order to place the annotations next to the concepts, Johannes must assign names to the nodes of the
concepts. He could rely on Tik Z’s automatic naming of the nodes in a tree, where the children of a node
named root are named root-1, root-2, root-3, and so on. However, since Johannes is not sure about
the final order of the concepts in the tree, it seems better to explicitly name all concepts of the tree in the
following manner:
Fixed-
Describing
Random-
Comparing
Parameter
\node
[root concept]
(Computational Complexity)
{Computational
Complexity}
Complexity
Complexity
ization
Algorithms
child [computational problems] { node (Computational Problems) {Computational Problems}
child
{ node (Problem Measures) {Problem Measures} }
child
{ node (Problem Aspects) {Problem Aspects} }
Parallel
child [faded] { node (Problem
Domains) {Problem Domains} }
Exact
Classifying
CompuComplexity
child
{ node (KeyAlgorithms
Problems) {Key Problems} }
tation
}
Measuring
...
Solving
ComThe annotation
Problems style of the mind map library mainly sets up a rectangular shape of appropriate size.
plexity
Johannes configures the style by defining every annotation appropriately.
Partial
Solutions
Complexity
Lecture 1: Computational
ApproxProblems
imation
• Knowledge of several
key problems
Measures
\begin{tikzpicture}[mindmap]
\clip (-5,-5) rectangle ++ (4,5);
\begin{scope}[
every node/.style={concept, circular drop shadow, ...}] % as before
\node [root concept] (Computational Complexity)
...
% as before
\end{scope}
Computational
• Knowledge of problem
encodings
• Being able to formalize
problems
Problem
Measures
Computational
Problems
Problem
Aspects
Program-
Complexity
\begin{scope}[every
ming in
annotation/.style={fill=black!40}]
\node [annotation, above] at Logic
(Computational Problems.north) {
Lecture 1: Computational Problems
\begin{itemize}
\item Knowledge of several key problems
Oracle
\item Knowledge of problem encodingsMachines
\item Being able to formalize problems
\end{itemize}
Compu};
tational
\end{scope}
Models
\end{tikzpicture}
Binary
Turing
Decision
Well, that does not yet look quite
perfect. The spacing or the {itemize}
is not really appropriate and
Machines
Diagrams
the node is too large. Johannes can configure these things “by hand,” but it seems like a good idea to define
a macro that will take care of these things for him. The “right” way to do this is to define a \lecture macro
RandomthatProblem
takes a list of Key
key-value pairs as argument
and produces the desired annotation. However, to keep
Access
Circuits
Domains
Problems \lecture macro simply takes a fixed number of arguments having the following
things
simple, Johannes’
Machines
meaning: The first argument is the number of the lecture, the second is the name of the lecture, the third
are positioning options like above, the fourth is the position where the node is placed, the fifth is the list of
items to be shown, and the sixth is a date when the lecture will be held (this parameter is not yet needed,
we will, however, need it later on).
\def\lecture#1#2#3#4#5#6{
\node [annotation, #3, scale=0.65, text width=4cm, inner sep=2mm] at (#4) {
Lecture #1: \textcolor{orange}{\textbf{#2}}
\list{--}{\topsep=2pt\itemsep=0pt\parsep=0pt
\parskip=0pt\labelwidth=8pt\leftmargin=8pt
\itemindent=0pt\labelsep=2pt}
#5
\endlist
};
}
82
Parallel
Computation
Exact
Algorithms
Classifying
Complexity
Measuring
Complexity
Solving
Problems
Partial
Solutions
Complexity
Measures
\begin{tikzpicture}[mindmap,every annotation/.style={fill=white}]
\clip (-5,-5) rectangle ++ (4,5);
\begin{scope}[
every node/.style={concept, circular drop shadow, ... % as before
\node [root concept] (Computational Complexity)
... % as before
\end{scope}
Computational
Approximation
Complexity
\lecture{1}{Computational
Lecture 1: Computational
Problems
– Knowledge of several key problems
– Knowledge of problem encodings
– Being able to formalize problems
Problem
Measures
Program-
ming in
Problems}{above,xshift=-3mm}
{Computational Problems.north}{Logic
\item Knowledge of several key problems
\item Knowledge of problem encodings
\item Being able to formalize problems Oracle
}{2009-04-08}
Machines
\end{tikzpicture}
Compu]
Computational
tational
In theProblems
same fashion Johannes can now add the
other lecture annotations. Obviously, Johannes will
Models
have
some
trouble
fitting
everything
on
a
single
A4-sized
page, but Binary
by adjusting the spacing and some
Problem
Turing
Decision
Aspects experimentation he can quickly arrange
all the annotations as needed.Diagrams
Machines
6.5
Adding the Background
Problem
Johannes
Domainshas
Key
Random-
Access
already
used colors to organize Machines
his
lecture mapCircuits
into four regions, each having a different color.
Problems
In order to emphasize these regions even more strongly, he wishes to add a background coloring to each of
these regions.
Adding these background colors turns out to be more tricky than Johannes would have thought. At
first sight, what he needs is some sort of “color wheel” that is blue in the lower right direction and then
changes smoothly to orange in the upper right direction and then to green in the upper left direction and so
on. Unfortunately, there is no easy way of creating such a color wheel shading (although it can be done, in
principle, but only at a very high cost, see page 687 for an example).
Johannes decides to do something a bit more basic: He creates four large rectangles, one for each of the
four quadrants around the central concept, each colored with a light version of the quadrant. Then, in order
to “smooth” the change between adjacent rectangles, he puts four shadings on top of them.
Since these background rectangles should go “behind” everything else, Johannes puts all his background
stuff on the background layer.
In the following code, only the central concept is shown to save some space:
83
\begin{tikzpicture}[
mindmap,
concept color=black,
root concept/.append style={
concept,
circular drop shadow,
fill=white, line width=1ex,
text=black, font=\large\scshape}
]
\clip (-1.5,-5) rectangle ++(4,10);
\node [root concept] (Computational Complexity) {Computational Complexity};
Computational
Complexity
\begin{pgfonlayer}{background}
\clip (-1.5,-5) rectangle ++(4,10);
\colorlet{upperleft}{green!50!black!25}
\colorlet{upperright}{orange!25}
\colorlet{lowerleft}{red!25}
\colorlet{lowerright}{blue!25}
% The large rectangles:
\fill [upperleft] (Computational
\fill [upperright] (Computational
\fill [lowerleft] (Computational
\fill [lowerright] (Computational
Complexity)
Complexity)
Complexity)
Complexity)
rectangle
rectangle
rectangle
rectangle
++(-20,20);
++(20,20);
++(-20,-20);
++(20,-20);
% The shadings:
\shade [left color=upperleft,right color=upperright]
([xshift=-1cm]Computational Complexity) rectangle ++(2,20);
\shade [left color=lowerleft,right color=lowerright]
([xshift=-1cm]Computational Complexity) rectangle ++(2,-20);
\shade [top color=upperleft,bottom color=lowerleft]
([yshift=-1cm]Computational Complexity) rectangle ++(-20,2);
\shade [top color=upperright,bottom color=lowerright]
([yshift=-1cm]Computational Complexity) rectangle ++(20,2);
\end{pgfonlayer}
\end{tikzpicture}
6.6
Adding the Calendar
Johannes intends to plan his lecture rather carefully. In particular, he already knows when each of his
lectures will be held during the course. Naturally, this does not mean that Johannes will slavishly follow
the plan and he might need longer for some subjects than he anticipated, but nevertheless he has a detailed
plan of when which subject will be addressed.
Johannes intends to share this plan with his students by adding a calendar to the lecture map. In addition
to serving as a reference on which particular day a certain topic will be addressed, the calendar is also useful
to show the overall chronological order of the course.
In order to add a calendar to a Tik Z graphic, the calendar library is most useful. The library provides the
\calendar command, which takes a large number of options and which can be configured in many ways to
produce just about any kind of calendar imaginable. For Johannes’ purposes, a simple day list downward
will be a nice option since it produces a list of days that go “downward”.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
\tiny
\begin{tikzpicture}
\calendar [day list downward,
name=cal,
dates=2009-04-01 to 2009-04-14]
if (weekend)
[black!25];
\end{tikzpicture}
Using the name option, we gave a name to the calendar, which will allow us to reference the nodes that
make up the individual days of the calendar later on. For instance, the rectangular node containing the 1
that represents April 1st, 2009, can be referenced as (cal-2009-04-01). The dates option is used to specify
84
an interval for which the calendar should be drawn. Johannes will need several months in his calendar, but
the above example only shows two weeks to save some space.
Note the if (weekend) construct. The \calendar command is followed by options and then by
if-statements. These if-statements are checked for each day of the calendar and when a date passes
this test, the options or the code following the if-statement is executed. In the above example, we make
weekend days (Saturdays and Sundays, to be precise) lighter than normal days. (Use your favorite calendar
to check that, indeed, April 5th, 2009, is a Sunday.)
As mentioned above, Johannes can reference the nodes that are used to typeset days. Recall that his
\lecture macro already got passed a date, which we did not use, yet. We can now use it to place the
lecture’s title next to the date when the lecture will be held:
\def\lecture#1#2#3#4#5#6{
% As before:
\node [annotation, #3, scale=0.65, text width=4cm, inner sep=2mm] at (#4) {
Lecture #1: \textcolor{orange}{\textbf{#2}}
\list{--}{\topsep=2pt\itemsep=0pt\parsep=0pt
\parskip=0pt\labelwidth=8pt\leftmargin=8pt
\itemindent=0pt\labelsep=2pt}
#5
\endlist
};
% New:
\node [anchor=base west] at (cal-#6.base east) {\textcolor{orange}{\textbf{#2}}};
}
Johannes can now use this new \lecture command as follows (in the example, only the new part of the
definition is used):
1
2
3
4
5
6
7
8 Computational Problems
9
10
11
12
13
14
\tiny
\begin{tikzpicture}
\calendar [day list downward,
name=cal,
dates=2009-04-01 to 2009-04-14]
if (weekend)
[black!25];
% As before:
\lecture{1}{Computational Problems}{above,xshift=-3mm}
{Computational Problems.north}{
\item Knowledge of several key problems
\item Knowledge of problem encodings
\item Being able to formalize problems
}{2009-04-08}
\end{tikzpicture}
As a final step, Johannes needs to add a few more options to the calendar command: He uses the
month text option to configure how the text of a month is rendered (see Section 45 for details) and then
typesets the month text at a special position at the beginning of each month.
85
April 2009
1
2
3
4
5
6
7
8 Computational Problems
9
10
11
12
13
14
15 Computational Models
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
May 2009
1
6.7
\tiny
\begin{tikzpicture}
\calendar [day list downward,
month text=\%mt\ \%y0,
month yshift=3.5em,
name=cal,
dates=2009-04-01 to 2009-05-01]
if (weekend)
[black!25]
if (day of month=1) {
\node at (0pt,1.5em) [anchor=base west] {\small\tikzmonthtext};
};
\lecture{1}{Computational Problems}{above,xshift=-3mm}
{Computational Problems.north}{
\item Knowledge of several key problems
\item Knowledge of problem encodings
\item Being able to formalize problems
}{2009-04-08}
\lecture{2}{Computational Models}{above,xshift=-3mm}
{Computational Models.north}{
\item Knowledge of Turing machines
\item Being able to compare the computational power of different
models
}{2009-04-15}
\end{tikzpicture}
The Complete Code
Putting it all together, Johannes gets the following code:
First comes the definition of the \lecture command:
\def\lecture#1#2#3#4#5#6{
% As before:
\node [annotation, #3, scale=0.65, text width=4cm, inner sep=2mm, fill=white] at (#4) {
Lecture #1: \textcolor{orange}{\textbf{#2}}
\list{--}{\topsep=2pt\itemsep=0pt\parsep=0pt
\parskip=0pt\labelwidth=8pt\leftmargin=8pt
\itemindent=0pt\labelsep=2pt}
#5
\endlist
};
% New:
\node [anchor=base west] at (cal-#6.base east) {\textcolor{orange}{\textbf{#2}}};
}
This is followed by the main mindmap setup. . .
\noindent
\begin{tikzpicture}
\begin{scope}[
mindmap,
every node/.style={concept, circular drop shadow,execute at begin node=\hskip0pt},
root concept/.append style={
concept color=black,
fill=white, line width=1ex,
text=black, font=\large\scshape},
text=white,
computational problems/.style={concept color=red,faded/.style={concept color=red!50}},
computational models/.style={concept color=blue,faded/.style={concept color=blue!50}},
measuring complexity/.style={concept color=orange,faded/.style={concept color=orange!50}},
solving problems/.style={concept color=green!50!black,faded/.style={concept color=green!50!black!50}},
grow cyclic,
level 1/.append style={level distance=4.5cm,sibling angle=90,font=\scshape},
level 2/.append style={level distance=3cm,sibling angle=45,font=\scriptsize}]
. . . and contents:
86
\node [root concept] (Computational Complexity) {Computational Complexity} % root
child [computational problems] { node [yshift=-1cm] (Computational Problems) {Computational Problems}
child
{ node (Problem Measures) {Problem Measures} }
child
{ node (Problem Aspects) {Problem Aspects} }
child [faded] { node (problem Domains) {Problem Domains} }
child
{ node (Key Problems) {Key Problems} }
}
child [computational models] { node [yshift=-1cm] (Computational Models) {Computational Models}
child
{ node (Turing Machines) {Turing Machines} }
child [faded] { node (Random-Access Machines) {Random-Access Machines} }
child
{ node (Circuits) {Circuits} }
child [faded] { node (Binary Decision Diagrams) {Binary Decision Diagrams} }
child
{ node (Oracle Machines) {Oracle Machines} }
child
{ node (Programming in Logic) {Programming in Logic} }
}
child [measuring complexity] { node [yshift=1cm] (Measuring Complexity) {Measuring Complexity}
child
{ node (Complexity Measures) {Complexity Measures} }
child
{ node (Classifying Complexity) {Classifying Complexity} }
child
{ node (Comparing Complexity) {Comparing Complexity} }
child [faded] { node (Describing Complexity) {Describing Complexity} }
}
child [solving problems] { node [yshift=1cm] (Solving Problems) {Solving Problems}
child
{ node (Exact Algorithms) {Exact Algorithms} }
child
{ node (Randomization) {Randomization} }
child
{ node (Fixed-Parameter Algorithms) {Fixed-Parameter Algorithms} }
child
{ node (Parallel Computation) {Parallel Computation} }
child
{ node (Partial Solutions) {Partial Solutions} }
child
{ node (Approximation) {Approximation} }
};
\end{scope}
Now comes the calendar code:
\tiny
\calendar [day list downward,
month text=\%mt\ \%y0,
month yshift=3.5em,
name=cal,
at={(-.5\textwidth-5mm,.5\textheight-1cm)},
dates=2009-04-01 to 2009-06-last]
if (weekend)
[black!25]
if (day of month=1) {
\node at (0pt,1.5em) [anchor=base west] {\small\tikzmonthtext};
};
The lecture annotations:
\lecture{1}{Computational Problems}{above,xshift=-5mm,yshift=5mm}{Computational Problems.north}{
\item Knowledge of several key problems
\item Knowledge of problem encodings
\item Being able to formalize problems
}{2009-04-08}
\lecture{2}{Computational Models}{above left}
{Computational Models.west}{
\item Knowledge of Turing machines
\item Being able to compare the computational power of different
models
}{2009-04-15}
Finally, the background:
87
\begin{pgfonlayer}{background}
\clip[xshift=-1cm] (-.5\textwidth,-.5\textheight) rectangle ++(\textwidth,\textheight);
\colorlet{upperleft}{green!50!black!25}
\colorlet{upperright}{orange!25}
\colorlet{lowerleft}{red!25}
\colorlet{lowerright}{blue!25}
% The large rectangles:
\fill [upperleft] (Computational
\fill [upperright] (Computational
\fill [lowerleft] (Computational
\fill [lowerright] (Computational
Complexity)
Complexity)
Complexity)
Complexity)
rectangle
rectangle
rectangle
rectangle
++(-20,20);
++(20,20);
++(-20,-20);
++(20,-20);
% The shadings:
\shade [left color=upperleft,right color=upperright]
([xshift=-1cm]Computational Complexity) rectangle ++(2,20);
\shade [left color=lowerleft,right color=lowerright]
([xshift=-1cm]Computational Complexity) rectangle ++(2,-20);
\shade [top color=upperleft,bottom color=lowerleft]
([yshift=-1cm]Computational Complexity) rectangle ++(-20,2);
\shade [top color=upperright,bottom color=lowerright]
([yshift=-1cm]Computational Complexity) rectangle ++(20,2);
\end{pgfonlayer}
\end{tikzpicture}
The next page shows the resulting lecture map in all its glory (it would be somewhat more glorious, if
there were more lecture annotations, but you should get the idea).
88
April 2009
1
2
3
4
5
6
7
8 Computational Problems
9
10
11
12
13
14
15 Computational Models
16
17
18
19
20
21
22
23
24
25
26
Parallel
27
Compu28
29
tation
30
Comparing
Complexity
Exact
Algorithms
Classifying
Complexity
Measuring
Complexity
Partial
Solutions
Complexity
Measures
Approximation
Computational
Complexity
Programming in
Logic
Lecture 1: Computational
Problems
– Knowledge of several key problems
– Knowledge of problem encodings
– Being able to formalize problems
Problem
Measures
June 2009
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Describing
Complexity
Randomization
Solving
Problems
May 2009
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
FixedParameter
Algorithms
Oracle
Machines
Lecture 2: Computational Models
– Knowledge of Turing machines
– Being able to compare the
computational power of different
models
Computational
Problems
Problem
Aspects
Computational
Models
Binary
Decision
Diagrams
Turing
Machines
Problem
Domains
RandomAccess
Machines
Key
Problems
89
Circuits
7
Guidelines on Graphics
The present section is not about pgf or Tik Z, but about general guidelines and principles concerning the
creation of graphics for scientific presentations, papers, and books.
The guidelines in this section come from different sources. Many of them are just what I would like to claim
is “common sense,” some reflect my personal experience (though, hopefully, not my personal preferences),
some come from books (the bibliography is still missing, sorry) on graphic design and typography. The most
influential source are the brilliant books by Edward Tufte. While I do not agree with everything written
in these books, many of Tufte’s arguments are so convincing that I decided to repeat them in the following
guidelines.
The first thing you should ask yourself when someone presents a bunch of guidelines is: Should I really
follow these guidelines? This is an important question, because there are good reasons not to follow general
guidelines. The person who set up the guidelines may have had other objectives than you do. For example,
a guideline might say “use the color red for emphasis.” While this guideline makes perfect sense for, say,
a presentation using a projector, red “color” has the opposite effect of “emphasis” when printed using a
black-and-white printer. Guidelines were almost always set up to address a specific situation. If you are not
in this situation, following a guideline can do more harm than good.
The second thing you should be aware of is the basic rule of typography is: “Every rule can be broken, as
long as you are aware that you are breaking a rule.” This rule also applies to graphics. Phrased differently,
the basic rule states: “The only mistakes in typography are things done in ignorance.” When you are aware
of a rule and when you decide that breaking the rule has a desirable effect, break the rule.
7.1
Planning the Time Needed for the Creation of Graphics
When you create a paper with numerous graphics, the time needed to create these graphics becomes an
important factor. How much time should you calculate for the creation of graphics?
As a general rule, assume that a graphic will need as much time to create as would a text of the same
length. For example, when I write a paper, I need about one hour per page for the first draft. Later, I
need between two and four hours per page for revisions. Thus, I expect to need about half an hour for the
creation of a first draft of a half page graphic. Later on, I expect another one to two hours before the final
graphic is finished.
In many publications, even in good journals, the authors and editors have obviously invested a lot of time
on the text, but seem to have spend about five minutes to create all of the graphics. Graphics often seem to
have been added as an “afterthought” or look like a screen shot of whatever the authors’s statistical software
shows them. As will be argued later on, the graphics that programs like gnuplot produce by default are
of poor quality.
Creating informative graphics that help the reader and that fit together with the main text is a difficult,
lengthy process.
• Treat graphics as first-class citizens of your papers. They deserve as much time and energy as the text
does. Indeed, the creation of graphics might deserve even more time than the writing of the main text
since more attention will be paid to the graphics and they will be looked at first.
• Plan as much time for the creation and revision of a graphic as you would plan for text of the same
size.
• Difficult graphics with a high information density may require even more time.
• Very simple graphics will require less time, but most likely you do not want to have “very simple
graphics” in your paper, anyway; just as you would not like to have a “very simple text” of the same
size.
7.2
Workflow for Creating a Graphic
When you write a (scientific) paper, you will most likely follow the following pattern: You have some
results/ideas that you would like to report about. The creation of the paper will typically start with
compiling a rough outline. Then, the different sections are filled with text to create a first draft. This draft
is then revised repeatedly until, often after substantial revision, a final paper results. In a good journal
paper there is typically not be a single sentence that has survived unmodified from the first draft.
Creating a graphics follows the same pattern:
90
• Decide on what the graphic should communicate. Make this a conscious decision, that is, determine
“What is the graphic supposed to tell the reader?”
• Create an “outline,” that is, the rough overall “shape” of the graphic, containing the most crucial
elements. Often, it is useful to do this using pencil and paper.
• Fill out the finer details of the graphic to create a first draft.
• Revise the graphic repeatedly along with the rest of the paper.
7.3
Linking Graphics With the Main Text
Graphics can be placed at different places in a text. Either, they can be inlined, meaning they are somewhere
“in the middle of the text” or they can be placed in stand-alone “figures.” Since printers (the people) like to
have their pages “filled,” (both for aesthetic and economic reasons) stand-alone figures may traditionally be
placed on pages in the document far away from the main text that refers to them. LATEX and TEX tend to
encourage this “drifting away” of graphics for technical reasons.
When a graphic is inlined, it will more or less automatically be linked with the main text in the sense
that the labels of the graphic will be implicitly explained by the surrounding text. Also, the main text will
typically make it clear what the graphic is about and what is shown.
Quite differently, a stand-alone figure will often be viewed at a time when the main text that this graphic
belongs to either has not yet been read or has been read some time ago. For this reason, you should follow
the following guidelines when creating stand-alone figures:
• Stand-alone figures should have a caption than should make them “understandable by themselves.”
For example, suppose a graphic shows an example of the different stages of a quicksort algorithm. Then
the figure’s caption should, at the very least, inform the reader that “The figure shows the different
stages of the quicksort algorithm introduced on page xyz.” and not just “Quicksort algorithm.”
• A good caption adds as much context information as possible. For example, you could say: “The figure
shows the different stages of the quicksort algorithm introduced on page xyz. In the first line, the
pivot element 5 is chosen. This causes. . . ” While this information can also be given in the main text,
putting it in the caption will ensure that the context is kept. Do not feel afraid of a 5-line caption.
(Your editor may hate you for this. Consider hating them back.)
• Reference the graphic in your main text as in “For an example of quicksort ‘in action,’ see Figure 2.1
on page xyz.”
• Most books on style and typography recommend that you do not use abbreviations as in “Fig. 2.1” but
write “Figure 2.1.”
The main argument against abbreviations is that “a period is too valuable to waste it on an abbreviation.” The idea is that a period will make the reader assume that the sentence ends after “Fig” and it
takes a “conscious backtracking” to realize that the sentence did not end after all.
The argument in favor of abbreviations is that they save space.
Personally, I am not really convinced by either argument. On the one hand, I have not yet seen any
hard evidence that abbreviations slow readers down. On the other hand, abbreviating all “Figure” by
“Fig.” is most unlikely to save even a single line in most documents. I avoid abbreviations.
7.4
Consistency Between Graphics and Text
Perhaps the most common “mistake” people do when creating graphics (remember that a “mistake” in design
is always just “ignorance”) is to have a mismatch between the way their graphics look and the way their text
looks.
It is quite common that authors use several different programs for creating the graphics of a paper. An
author might produce some plots using gnuplot, a diagram using xfig, and include an .eps graphic a
coauthor contributed using some unknown program. All these graphics will, most likely, use different line
widths, different fonts, and have different sizes. In addition, authors often use options like [height=5cm]
when including graphics to scale them to some “nice size.”
If the same approach were taken to writing the main text, every section would be written in a different
font at a different size. In some sections all theorems would be underlined, in another they would be printed
91
all in uppercase letters, and in another in red. In addition, the margins would be different on each page.
Readers and editors would not tolerate a text if it were written in this fashion, but with graphics they often
have to.
To create consistency between graphics and text, stick to the following guidelines:
• Do not scale graphics.
This means that when generating graphics using an external program, create them “at the right size.”
• Use the same font(s) both in graphics and the body text.
• Use the same line width in text and graphics.
The “line width” for normal text is the width of the stem of letters like T. For TEX, this is usually
0.4 pt. However, some journals will not accept graphics with a normal line width below 0.5 pt.
• When using colors, use a consistent color coding in the text and in graphics. For example, if red is
supposed to alert the reader to something in the main text, use red also in graphics for important parts
of the graphic. If blue is used for structural elements like headlines and section titles, use blue also for
structural elements of your graphic.
However, graphics may also use a logical intrinsic color coding. For example, no matter what colors
you normally use, readers will generally assume, say, that the color green as “positive, go, ok” and red
as “alert, warning, action.”
Creating consistency when using different graphic programs is almost impossible. For this reason, you
should consider sticking to a single graphics program.
7.5
Labels in Graphics
Almost all graphics will contain labels, that is, pieces of text that explain parts of the graphics. When
placing labels, stick to the following guidelines:
• Follow the rule of consistency when placing labels. You should do so in two ways: First, be consistent
with the main text, that is, use the same font as the main text also for labels. Second, be consistent
between labels, that is, if you format some labels in some particular way, format all labels in this way.
• In addition to using the same fonts in text and graphics, you should also use the same notation. For
example, if you write 1/2 in your main text, also use “1/2” as labels in graphics, not “0.5”. A π is a
“π” and not “3.141”. Finally, e−iπ is “e−iπ ”, not “−1”, let alone “-1”.
• Labels should be legible. They should not only have a reasonably large size, they also should not be
obscured by lines or other text. This also applies to labels of lines and text behind the labels.
• Labels should be “in place.” Whenever there is enough space, labels should be placed next to the
thing they label. Only if necessary, add a (subdued) line from the label to the labeled object. Try to
avoid labels that only reference explanations in external legends. Reader have to jump back and forth
between the explanation and the object that is described.
• Consider subduing “unimportant” labels using, for example, a gray color. This will keep the focus on
the actual graphic.
7.6
Plots and Charts
One of the most frequent kind of graphics, especially in scientific papers, are plots. They come in a large
variety, including simple line plots, parametric plots, three dimensional plots, pie charts, and many more.
Unfortunately, plots are notoriously hard to get right. Partly, the default settings of programs like
gnuplot or Excel are to blame for this since these programs make it very convenient to create bad plots.
The first question you should ask yourself when creating a plot is: Are there enough data points to merit
a plot? If the answer is “not really,” use a table.
A typical situation where a plot is unnecessary is when people present a few numbers in a bar diagram.
Here is a real-life example: At the end of a seminar a lecturer asked the participants for feedback. Of the 50
participants, 30 returned the feedback form. According to the feedback, three participants considered the
92
seminar “very good,” nine considered it “good,” ten “ok,” eight “bad,” and no one thought that the seminar
was “very bad.”
A simple way of summing up this information is the following table:
Rating given
Participants (out of 50)
who gave this rating
Percentage
“very good”
“good”
“ok”
“bad”
“very bad”
3
9
10
8
0
6%
18%
20%
16%
0%
none
20
40%
What the lecturer did was to visualize the data using a 3D bar diagram. It looked like this (except
that in reality the numbers where typeset using some extremely low-resolution bitmap font and were nearunreadable):
100
80
60
40
very bad
bad
ok
good
0
very good
20
Both the table and the “plot” have about the same size. If your first thought is “the graphic looks nicer
than the table,” try to answer the following questions based on the information in the table or in the graphic:
1. How many participants where there?
2. How many participants returned the feedback form?
3. What percentage of the participants returned the feedback form?
4. How many participants checked “very good”?
5. What percentage out of all participants checked “very good”?
6. Did more than a quarter of the participants check “bad” or “very bad”?
7. What percentage of the participants that returned the form checked “very good”?
Sadly, the graphic does not allow us to answer a single one of these questions. The table answers all of
them directly, except for the last one. In essence, the information density of the graphic is very close to zero.
The table has a much higher information density; despite the fact that it uses quite a lot of white space to
present a few numbers. Here is the list of things that went wrong with the 3D-bar diagram:
• The whole graphic is dominated by irritating background lines.
• It is not clear what the numbers at the left mean; presumably percentages, but it might also be the
absolute number of participants.
• The labels at the bottom are rotated, making them hard to read.
(In the real presentation that I saw, the text was rendered at a very low resolution with about 10 by
6 pixels per letter with wrong kerning, making the rotated text almost impossible to read.)
• The third dimension adds complexity to the graphic without adding information.
93
• The three dimensional setup makes it much harder to gauge the height of the bars correctly. Consider
the “bad” bar. It the number this bar stands for more than 20 or less? While the front of the bar is
below the 20 line, the back of the bar (which counts) is above.
• It is impossible to tell which numbers are represented by the bars. Thus, the bars needlessly hide the
information these bars are all about.
• What do the bar heights add up to? Is it 100% or 60%?
• Does the bar for “very bad” represent 0 or 1?
• Why are the bars blue?
You might argue that in the example the exact numbers are not important for the graphic. The important
things is the “message,” which is that there are more “very good” and “good” ratings than “bad” and “very
bad.” However, to convey this message either use a sentence that says so or use a graphic that conveys this
message more clearly:
none: 20 (40%)
“very good”: 3 (6%)
Ratings given by
50 participants
“very bad”: 0 (0%)
“good”: 9 (18%)
“bad”: 8 (16%)
“ok”: 10 (20%)
The above graphic has about the same information density as the table (about the same size and the
same numbers are shown). In addition, one can directly “see” that there are more good or very good ratings
than bad ones. One can also “see” that the number of people who gave no rating at all is not negligible,
which is quite common for feedback forms.
Charts are not always a good idea. Let us look at an example that I redrew from a pie chart in Die Zeit,
June 4th, 2005:
Kohle ist am wichtigsten
Energiemix bei der deutschen Stromerzeugung 2004
Gesamte Netto-Stromerzeugung in Prozent, in Milliarden Kilowattstunden (Mrd. kWh)
Sonstige (16,5 kWh)
2,9%
Regenerative (53,7 kWh)/davon Wind 4,4% (25,0 kWh)
Mineralölprodukte (9,2 kWh) 1,6%
Erdgas (59,2 kWh)
9,4%
27,8%
10,4%
Kernenergie
(158,4 kWh)
22,3%
Steinkohle (127,1 kWh)
25,6%
Braunkohle (146,0 kWh)
This graphic has been redrawn in Tik Z, but the original looks almost exactly the same.
At first sight, the graphic looks “nice and informative,” but there are a lot of things that went wrong:
• The chart is three dimensional. However, the shadings add nothing “information-wise,” at best, they
distract.
94
• In a 3D-pie-chart the relative sizes are very strongly distorted. For example, the area taken up by the
gray color of “Braunkohle” is larger than the area taken up by the green color of “Kernenergie” despite
the fact that the percentage of Braunkohle is less than the percentage of Kernenergie.
• The 3D-distortion gets worse for small areas. The area of “Regenerative” somewhat larger than the
area of “Erdgas.” The area of “Wind” is slightly smaller than the area of “Mineralölprodukte” although
the percentage of Wind is nearly three times larger than the percentage of Mineralölprodukte.
In the last case, the different sizes are only partly due to distortion. The designer(s) of the original
graphic have also made the “Wind” slice too small, even taking distortion into account. (Just compare
the size of “Wind” to “Regenerative” in general.)
• According to its caption, this chart is supposed to inform us that coal was the most important energy
source in Germany in 2004. Ignoring the strong distortions caused by the superfluous and misleading
3D-setup, it takes quite a while for this message to get across.
Coal as an energy source is split up into two slices: one for “Steinkohle” and one for “Braunkohle” (two
different kinds of coal). When you add them up, you see that the whole lower half of the pie chart is
taken up by coal.
The two areas for the different kinds of coal are not visually linked at all. Rather, two different colors
are used, the labels are on different sides of the graphic. By comparison, “Regenerative” and “Wind”
are very closely linked.
• The color coding of the graphic follows no logical pattern at all. Why is nuclear energy green? Regenerative energy is light blue, “other sources” are blue. It seems more like a joke that the area for
“Braunkohle” (which literally translates to “brown coal”) is stone gray, while the area for “Steinkohle”
(which literally translates to “stone coal”) is brown.
• The area with the lightest color is used for “Erdgas.” This area stands out most because of the brighter
color. However, for this chart “Erdgas” is not really important at all.
Edward Tufte calls graphics like the above “chart junk.” (I am happy to announce, however, that Die Zeit
has stopped using 3D pie charts and their information graphics have got somewhat better.)
Here are a few recommendations that may help you avoid producing chart junk:
• Do not use 3D pie charts. They are evil.
• Consider using a table instead of a pie chart.
• Do not apply colors randomly; use them to direct the readers’s focus and to group things.
• Do not use background patterns, like a crosshatch or diagonal lines, instead of colors. They distract.
Background patterns in information graphics are evil.
7.7
Attention and Distraction
Pick up your favorite fiction novel and have a look at a typical page. You will notice that the page is very
uniform. Nothing is there to distract the reader while reading; no large headlines, no bold text, no large
white areas. Indeed, even when the author does wish to emphasize something, this is done using italic
letters. Such letters blend nicely with the main text—at a distance you will not be able to tell whether a
page contains italic letters, but you would notice a single bold word immediately. The reason novels are
typeset this way is the following paradigm: Avoid distractions.
Good typography (like good organization) is something you do not notice. The job of typography is to
make reading the text, that is, “absorbing” its information content, as effortless as possible. For a novel,
readers absorb the content by reading the text line-by-line, as if they were listening to someone telling the
story. In this situation anything on the page that distracts the eye from going quickly and evenly from line
to line will make the text harder to read.
Now, pick up your favorite weekly magazine or newspaper and have a look at a typical page. You will
notice that there is quite a lot “going on” on the page. Fonts are used at different sizes and in different
arrangements, the text is organized in narrow columns, typically interleaved with pictures. The reason
magazines are typeset in this way is another paradigm: Steer attention.
Readers will not read a magazine like a novel. Instead of reading a magazine line-by-line, we use headlines
and short abstracts to check whether we want to read a certain article or not. The job of typography is to
95
steer our attention to these abstracts and headlines, first. Once we have decided that we want to read an
article, however, we no longer tolerate distractions, which is why the main text of articles is typeset exactly
the same way as a novel.
The two principles “avoid distractions” and “steer attention” also apply to graphics. When you design a
graphic, you should eliminate everything that will “distract the eye.” At the same time, you should try to
actively help the reader “through the graphic” by using fonts/colors/line widths to highlight different parts.
Here is a non-exhaustive list of things that can distract readers:
• Strong contrasts will always be registered first by the eye. For example, consider the following two
grids:
Even though the left grid comes first in English reading order, the right one is much more likely to
be seen first: The white-to-black contrast is higher than the gray-to-white contrast. In addition, there
are more “places” adding to the overall contrast in the right grid.
Things like grids and, more generally, help lines usually should not grab the attention of the readers
and, hence, should be typeset with a low contrast to the background. Also, a loosely-spaced grid is
less distracting than a very closely-spaced grid.
• Dashed lines create many points at which there is black-to-white contrast. Dashed or dotted lines can
be very distracting and, hence, should be avoided in general.
Do not use different dashing patterns to differentiate curves in plots. You lose data points this way
and the eye is not particularly good at “grouping things according to a dashing pattern.” The eye is
much better at grouping things according to colors.
• Background patterns filling an area using diagonal lines or horizontal and vertical lines or just dots are
almost always distracting and, usually, serve no real purpose.
• Background images and shadings distract and only seldomly add anything of importance to a graphic.
• Cute little clip arts can easily draw attention away from the data.
96
Part II
Installation and Configuration
by Till Tantau
This part explains how the system is installed. Typically, someone has already done so for your system, so
this part can be skipped; but if this is not the case and you are the poor fellow who has to do the installation,
read the present part.
1,1,L
qb
0,1,L
start
0,1,L
1,1,R
qa
0,1,R
The current candidate for the busy beaver for five
states. It is presumed that this Turing machine
writes a maximum number of 1’s before halting
among all Turing machines with five states and the
tape alphabet {0, 1}. Proving this conjecture is an
open research problem.
qc
0,1,L
qd
1,0,R
1,1,R
1,0,R
qe
\begin{tikzpicture}[->,>=stealth’,shorten >=1pt,auto,node distance=2.8cm,on grid,semithick,
every state/.style={fill=red,draw=none,circular drop shadow,text=white}]
\node[initial,state]
\node[state]
\node[state]
\node[state]
\node[state]
\path (A) edge
edge
(B) edge
edge
(C) edge
edge
(D) edge
edge
(E) edge
(A)
(B)
(D)
(C)
(E)
{$q_a$};
[above right=of A] {$q_b$};
[below right=of A] {$q_d$};
[below right=of B] {$q_c$};
[below=of D]
{$q_e$};
node
node
[loop above] node
node
node
[bend left] node
[loop below] node
node
[bend left] node
{0,1,L}
{1,1,R}
{1,1,L}
{0,1,L}
{0,1,L}
{1,0,R}
{1,1,R}
{0,1,R}
{1,0,R}
(B)
(C)
(B)
(C)
(D)
(E)
(D)
(A)
(A);
\node [right=1cm,text width=8cm] at (C)
{
The current candidate for the busy beaver for five states. It is
presumed that this Turing machine writes a maximum number of
$1$’s before halting among all Turing machines with five states
and the tape alphabet $\{0, 1\}$. Proving this conjecture is an
open research problem.
};
\end{tikzpicture}
97
8
Installation
There are different ways of installing pgf, depending on your system and needs, and you may need to install
other packages as well, see below. Before installing, you may wish to review the licenses under which the
package is distributed, see Section 9.
Typically, the package will already be installed on your system. Naturally, in this case you do not need
to worry about the installation process at all and you can skip the rest of this section.
8.1
Package and Driver Versions
This documentation is part of version 3.0.1a of the pgf package. In order to run pgf, you need a reasonably
recent TEX installation. When using LATEX, you need the following packages installed (newer versions should
also work):
• xcolor version 2.00.
With plain TEX, xcolor is not needed, but you obviously do not get its (full) functionality.
Currently, pgf supports the following backend drivers:
• luatex version 0.76 or higher. Most earlier versions also work.
• pdftex version 0.14 or higher. Earlier versions do not work.
• dvips version 5.94a or higher. Earlier versions may also work.
For inter-picture connections, you need to process pictures using pdftex version 1.40 or higher running
in DVI mode.
• dvipdfm version 0.13.2c or higher. Earlier versions may also work.
For inter-picture connections, you need to process pictures using pdftex version 1.40 or higher running
in DVI mode.
• dvipdfmx version 0.13.2c or higher. Earlier versions may also work.
• dvisvgm version 1.2.2 or higher. Earlier versions may also work.
• tex4ht version 2003-05-05 or higher. Earlier versions may also work.
• vtex version 8.46a or higher. Earlier versions may also work.
• textures version 2.1 or higher. Earlier versions may also work.
• xetex version 0.996 or higher. Earlier versions may also work.
Currently, pgf supports the following formats:
• latex with complete functionality.
• plain with complete functionality, except for graphics inclusion, which works only for pdfTEX.
• context with complete functionality, except for graphics inclusion, which works only for pdfTEX.
For more details, see Section 10.
8.2
Installing Prebundled Packages
I do not create or manage prebundled packages of pgf, but, fortunately, nice other people do. I cannot give
detailed instructions on how to install these packages, since I do not manage them, but I can tell you were
to find them. If you have a problem with installing, you might wish to have a look at the Debian page or
the MiKTEX page first.
8.2.1
Debian
The command “aptitude install pgf” should do the trick. Sit back and relax.
98
8.2.2
MiKTeX
For MiKTEX, use the update wizard to install the (latest versions of the) packages called pgf and xcolor.
8.3
Installation in a texmf Tree
For a permanent installation, you place the files of the pgf package in an appropriate texmf tree.
When you ask TEX to use a certain class or package, it usually looks for the necessary files in so-called
texmf trees. These trees are simply huge directories that contain these files. By default, TEX looks for files
in three different texmf trees:
• The root texmf tree, which is usually located at /usr/share/texmf/ or c:\texmf\ or somewhere
similar.
• The local texmf tree, which is usually located at /usr/local/share/texmf/ or c:\localtexmf\ or
somewhere similar.
• Your personal texmf tree, which is usually located in your home directory at ~/texmf/ or
~/Library/texmf/.
You should install the packages either in the local tree or in your personal tree, depending on whether
you have write access to the local tree. Installation in the root tree can cause problems, since an update of
the whole TEX installation will replace this whole tree.
8.3.1
Installation that Keeps Everything Together
Once you have located the right texmf tree, you must decide whether you want to install pgf in such a way
that “all its files are kept in one place” or whether you want to be “tds-compliant,” where tds means “TEX
directory structure.”
If you want to keep “everything in one place,” inside the texmf tree that you have chosen create a
sub-sub-directory called texmf/tex/generic/pgf or texmf/tex/generic/pgf-3.0.1a, if you prefer. Then
place all files of the pgf package in this directory. Finally, rebuild TEX’s filename database. This is done by
running the command texhash or mktexlsr (they are the same). In MiKTEX, there is a menu option to do
this.
8.3.2
Installation that is TDS-Compliant
While the above installation process is the most “natural” one and although I would like to recommend it
since it makes updating and managing the pgf package easy, it is not tds-compliant. If you want to be
tds-compliant, proceed as follows: (If you do not know what tds-compliant means, you probably do not
want to be tds-compliant.)
The .tar file of the pgf package contains the following files and directories at its root: README, doc,
generic, plain, and latex. You should “merge” each of the four directories with the following directories
texmf/doc, texmf/tex/generic, texmf/tex/plain, and texmf/tex/latex. For example, in the .tar file
the doc directory contains just the directory pgf, and this directory has to be moved to texmf/doc/pgf.
The root README file can be ignored since it is reproduced in doc/pgf/README.
You may also consider keeping everything in one place and using symbolic links to point from the
tds-compliant directories to the central installation.
For a more detailed explanation of the standard installation process of packages, you might wish to
consult http://www.ctan.org/installationadvice/. However, note that the pgf package does not come
with a .ins file (simply skip that part).
8.4
Updating the Installation
To update your installation from a previous version, all you need to do is to replace everything in the directory
texmf/tex/generic/pgf with the files of the new version (or in all the directories where pgf was installed,
if you chose a tds-compliant installation). The easiest way to do this is to first delete the old version and
then proceed as described above. Sometimes, there are changes in the syntax of certain commands from
version to version. If things no longer work that used to work, you may wish to have a look at the release
notes and at the change log.
99
9
Licenses and Copyright
9.1
Which License Applies?
Different parts of the pgf package are distributed under different licenses:
1. The code of the package is dual-license. This means that you can decide which license you wish to use
when using the pgf package. The two options are:
(a) You can use the gnu Public License, version 2.
(b) You can use the LATEX Project Public License, version 1.3c.
2. The documentation of the package is also dual-license. Again, you can choose between two options:
(a) You can use the gnu Free Documentation License, version 1.2.
(b) You can use the LATEX Project Public License, version 1.3c.
The “documentation of the package” refers to all files in the subdirectory doc of the pgf package. A
detailed listing can be found in the file doc/generic/pgf/licenses/manifest-documentation.txt. All
files in other directories are part of the “code of the package.” A detailed listing can be found in the file
doc/generic/pgf/licenses/manifest-code.txt.
In the rest of this section, the licenses are presented. The following text is copyrighted, see the plain text
versions of these licenses in the directory doc/generic/pgf/licenses for details.
The example picture used in this manual, the Brave gnu World logo, is taken from the Brave gnu World
homepage, where it is copyrighted as follows: “Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004 Georg
C. F. Greve. Permission is granted to make and distribute verbatim copies of this transcript as long as the
copyright and this permission notice appear.”
9.2
9.2.1
The GNU Public License, Version 2
Preamble
The licenses for most software are designed to take away your freedom to share and change it. By contrast,
the gnu General Public License is intended to guarantee your freedom to share and change free software—to
make sure the software is free for all its users. This General Public License applies to most of the Free
Software Foundation’s software and to any other program whose authors commit to using it. (Some other
Free Software Foundation software is covered by the gnu Library General Public License instead.) You can
apply it to your programs, too.
When we speak of free software, we are referring to freedom, not price. Our General Public Licenses
are designed to make sure that you have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it if you want it, that you can change the
software or use pieces of it in new free programs; and that you know you can do these things.
To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask
you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute
copies of the software, or if you modify it.
For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the
recipients all the rights that you have. You must make sure that they, too, receive or can get the source
code. And you must show them these terms so they know their rights.
We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which
gives you legal permission to copy, distribute and/or modify the software.
Also, for each author’s protection and ours, we want to make certain that everyone understands that
there is no warranty for this free software. If the software is modified by someone else and passed on, we
want its recipients to know that what they have is not the original, so that any problems introduced by
others will not reflect on the original authors’ reputations.
Finally, any free program is threatened constantly by software patents. We wish to avoid the danger
that redistributors of a free program will individually obtain patent licenses, in effect making the program
proprietary. To prevent this, we have made it clear that any patent must be licensed for everyone’s free use
or not licensed at all.
The precise terms and conditions for copying, distribution and modification follow.
100
9.2.2
Terms and Conditions For Copying, Distribution and Modification
0. This License applies to any program or other work which contains a notice placed by the copyright
holder saying it may be distributed under the terms of this General Public License. The “Program”,
below, refers to any such program or work, and a “work based on the Program” means either the
Program or any derivative work under copyright law: that is to say, a work containing the Program
or a portion of it, either verbatim or with modifications and/or translated into another language.
(Hereinafter, translation is included without limitation in the term “modification”.) Each licensee is
addressed as “you”.
Activities other than copying, distribution and modification are not covered by this License; they are
outside its scope. The act of running the Program is not restricted, and the output from the Program
is covered only if its contents constitute a work based on the Program (independent of having been
made by running the Program). Whether that is true depends on what the Program does.
1. You may copy and distribute verbatim copies of the Program’s source code as you receive it, in any
medium, provided that you conspicuously and appropriately publish on each copy an appropriate
copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and
to the absence of any warranty; and give any other recipients of the Program a copy of this License
along with the Program.
You may charge a fee for the physical act of transferring a copy, and you may at your option offer
warranty protection in exchange for a fee.
2. You may modify your copy or copies of the Program or any portion of it, thus forming a work based on
the Program, and copy and distribute such modifications or work under the terms of Section 1 above,
provided that you also meet all of these conditions:
(a) You must cause the modified files to carry prominent notices stating that you changed the files
and the date of any change.
(b) You must cause any work that you distribute or publish, that in whole or in part contains or is
derived from the Program or any part thereof, to be licensed as a whole at no charge to all third
parties under the terms of this License.
(c) If the modified program normally reads commands interactively when run, you must cause it,
when started running for such interactive use in the most ordinary way, to print or display an
announcement including an appropriate copyright notice and a notice that there is no warranty
(or else, saying that you provide a warranty) and that users may redistribute the program under
these conditions, and telling the user how to view a copy of this License. (Exception: if the
Program itself is interactive but does not normally print such an announcement, your work based
on the Program is not required to print an announcement.)
These requirements apply to the modified work as a whole. If identifiable sections of that work are
not derived from the Program, and can be reasonably considered independent and separate works in
themselves, then this License, and its terms, do not apply to those sections when you distribute them
as separate works. But when you distribute the same sections as part of a whole which is a work based
on the Program, the distribution of the whole must be on the terms of this License, whose permissions
for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote
it.
Thus, it is not the intent of this section to claim rights or contest your rights to work written entirely
by you; rather, the intent is to exercise the right to control the distribution of derivative or collective
works based on the Program.
In addition, mere aggregation of another work not based on the Program with the Program (or with a
work based on the Program) on a volume of a storage or distribution medium does not bring the other
work under the scope of this License.
3. You may copy and distribute the Program (or a work based on it, under Section 2) in object code
or executable form under the terms of Sections 1 and 2 above provided that you also do one of the
following:
(a) Accompany it with the complete corresponding machine-readable source code, which must be
distributed under the terms of Sections 1 and 2 above on a medium customarily used for software
interchange; or,
101
(b) Accompany it with a written offer, valid for at least three years, to give any third party, for a charge
no more than your cost of physically performing source distribution, a complete machine-readable
copy of the corresponding source code, to be distributed under the terms of Sections 1 and 2
above on a medium customarily used for software interchange; or,
(c) Accompany it with the information you received as to the offer to distribute corresponding source
code. (This alternative is allowed only for noncommercial distribution and only if you received
the program in object code or executable form with such an offer, in accord with Subsubsection
b above.)
The source code for a work means the preferred form of the work for making modifications to it. For
an executable work, complete source code means all the source code for all modules it contains, plus
any associated interface definition files, plus the scripts used to control compilation and installation of
the executable. However, as a special exception, the source code distributed need not include anything
that is normally distributed (in either source or binary form) with the major components (compiler,
kernel, and so on) of the operating system on which the executable runs, unless that component itself
accompanies the executable.
If distribution of executable or object code is made by offering access to copy from a designated place,
then offering equivalent access to copy the source code from the same place counts as distribution of
the source code, even though third parties are not compelled to copy the source along with the object
code.
4. You may not copy, modify, sublicense, or distribute the Program except as expressly provided under
this License. Any attempt otherwise to copy, modify, sublicense or distribute the Program is void,
and will automatically terminate your rights under this License. However, parties who have received
copies, or rights, from you under this License will not have their licenses terminated so long as such
parties remain in full compliance.
5. You are not required to accept this License, since you have not signed it. However, nothing else
grants you permission to modify or distribute the Program or its derivative works. These actions
are prohibited by law if you do not accept this License. Therefore, by modifying or distributing the
Program (or any work based on the Program), you indicate your acceptance of this License to do so,
and all its terms and conditions for copying, distributing or modifying the Program or works based on
it.
6. Each time you redistribute the Program (or any work based on the Program), the recipient automatically receives a license from the original licensor to copy, distribute or modify the Program subject to
these terms and conditions. You may not impose any further restrictions on the recipients’ exercise
of the rights granted herein. You are not responsible for enforcing compliance by third parties to this
License.
7. If, as a consequence of a court judgment or allegation of patent infringement or for any other reason
(not limited to patent issues), conditions are imposed on you (whether by court order, agreement or
otherwise) that contradict the conditions of this License, they do not excuse you from the conditions
of this License. If you cannot distribute so as to satisfy simultaneously your obligations under this
License and any other pertinent obligations, then as a consequence you may not distribute the Program
at all. For example, if a patent license would not permit royalty-free redistribution of the Program
by all those who receive copies directly or indirectly through you, then the only way you could satisfy
both it and this License would be to refrain entirely from distribution of the Program.
If any portion of this section is held invalid or unenforceable under any particular circumstance, the
balance of the section is intended to apply and the section as a whole is intended to apply in other
circumstances.
It is not the purpose of this section to induce you to infringe any patents or other property right claims
or to contest validity of any such claims; this section has the sole purpose of protecting the integrity of
the free software distribution system, which is implemented by public license practices. Many people
have made generous contributions to the wide range of software distributed through that system in
reliance on consistent application of that system; it is up to the author/donor to decide if he or she is
willing to distribute software through any other system and a licensee cannot impose that choice.
This section is intended to make thoroughly clear what is believed to be a consequence of the rest of
this License.
102
8. If the distribution and/or use of the Program is restricted in certain countries either by patents or by
copyrighted interfaces, the original copyright holder who places the Program under this License may
add an explicit geographical distribution limitation excluding those countries, so that distribution is
permitted only in or among countries not thus excluded. In such case, this License incorporates the
limitation as if written in the body of this License.
9. The Free Software Foundation may publish revised and/or new versions of the General Public License
from time to time. Such new versions will be similar in spirit to the present version, but may differ in
detail to address new problems or concerns.
Each version is given a distinguishing version number. If the Program specifies a version number of
this License which applies to it and “any later version”, you have the option of following the terms and
conditions either of that version or of any later version published by the Free Software Foundation.
If the Program does not specify a version number of this License, you may choose any version ever
published by the Free Software Foundation.
10. If you wish to incorporate parts of the Program into other free programs whose distribution conditions
are different, write to the author to ask for permission. For software which is copyrighted by the Free
Software Foundation, write to the Free Software Foundation; we sometimes make exceptions for this.
Our decision will be guided by the two goals of preserving the free status of all derivatives of our free
software and of promoting the sharing and reuse of software generally.
9.2.3
No Warranty
10. Because the program is licensed free of charge, there is no warranty for the program, to the extent
permitted by applicable law. Except when otherwise stated in writing the copyright holders and/or
other parties provide the program “as is” without warranty of any kind, either expressed or implied,
including, but not limited to, the implied warranties of merchantability and fitness for a particular
purpose. The entire risk as to the quality and performance of the program is with you. Should the
program prove defective, you assume the cost of all necessary servicing, repair or correction.
11. In no event unless required by applicable law or agreed to in writing will any copyright holder, or
any other party who may modify and/or redistribute the program as permitted above, be liable to
you for damages, including any general, special, incidental or consequential damages arising out of the
use or inability to use the program (including but not limited to loss of data or data being rendered
inaccurate or losses sustained by you or third parties or a failure of the program to operate with any
other programs), even if such holder or other party has been advised of the possibility of such damages.
9.3
9.3.1
The LATEX Project Public License, Version 1.3c 2006-05-20
Preamble
The LATEX Project Public License (lppl) is the primary license under which the LATEX kernel and the base
LATEX packages are distributed.
You may use this license for any work of which you hold the copyright and which you wish to distribute.
This license may be particularly suitable if your work is TEX-related (such as a LATEX package), but it is
written in such a way that you can use it even if your work is unrelated to TEX.
The section ‘whether and how to distribute works under this license’, below, gives instructions, examples, and recommendations for authors who are considering distributing their works under this
license.
This license gives conditions under which a work may be distributed and modified, as well as conditions
under which modified versions of that work may be distributed.
We, the LATEX3 Project, believe that the conditions below give you the freedom to make and distribute
modified versions of your work that conform with whatever technical specifications you wish while maintaining the availability, integrity, and reliability of that work. If you do not see how to achieve your goal while
meeting these conditions, then read the document ‘cfgguide.tex’ and ‘modguide.tex’ in the base LATEX
distribution for suggestions.
9.3.2
Definitions
In this license document the following terms are used:
103
Work Any work being distributed under this License.
Derived Work Any work that under any applicable law is derived from the Work.
Modification Any procedure that produces a Derived Work under any applicable law – for example, the
production of a file containing an original file associated with the Work or a significant portion of such
a file, either verbatim or with modifications and/or translated into another language.
Modify To apply any procedure that produces a Derived Work under any applicable law.
Distribution Making copies of the Work available from one person to another, in whole or in part. Distribution includes (but is not limited to) making any electronic components of the Work accessible by file
transfer protocols such as ftp or http or by shared file systems such as Sun’s Network File System
(nfs).
Compiled Work A version of the Work that has been processed into a form where it is directly usable on
a computer system. This processing may include using installation facilities provided by the Work,
transformations of the Work, copying of components of the Work, or other activities. Note that
modification of any installation facilities provided by the Work constitutes modification of the Work.
Current Maintainer A person or persons nominated as such within the Work. If there is no such explicit
nomination then it is the ‘Copyright Holder’ under any applicable law.
Base Interpreter A program or process that is normally needed for running or interpreting a part or the
whole of the Work.
A Base Interpreter may depend on external components but these are not considered part of the
Base Interpreter provided that each external component clearly identifies itself whenever it is used
interactively. Unless explicitly specified when applying the license to the Work, the only applicable
Base Interpreter is a ‘LATEX-Format’ or in the case of files belonging to the ‘LATEX-format’ a program
implementing the ‘TEX language’.
9.3.3
Conditions on Distribution and Modification
1. Activities other than distribution and/or modification of the Work are not covered by this license; they
are outside its scope. In particular, the act of running the Work is not restricted and no requirements
are made concerning any offers of support for the Work.
2. You may distribute a complete, unmodified copy of the Work as you received it. Distribution of only
part of the Work is considered modification of the Work, and no right to distribute such a Derived
Work may be assumed under the terms of this clause.
3. You may distribute a Compiled Work that has been generated from a complete, unmodified copy of
the Work as distributed under Clause 2 above, as long as that Compiled Work is distributed in such a
way that the recipients may install the Compiled Work on their system exactly as it would have been
installed if they generated a Compiled Work directly from the Work.
4. If you are the Current Maintainer of the Work, you may, without restriction, modify the Work, thus
creating a Derived Work. You may also distribute the Derived Work without restriction, including
Compiled Works generated from the Derived Work. Derived Works distributed in this manner by the
Current Maintainer are considered to be updated versions of the Work.
5. If you are not the Current Maintainer of the Work, you may modify your copy of the Work, thus
creating a Derived Work based on the Work, and compile this Derived Work, thus creating a Compiled
Work based on the Derived Work.
6. If you are not the Current Maintainer of the Work, you may distribute a Derived Work provided the
following conditions are met for every component of the Work unless that component clearly states in
the copyright notice that it is exempt from that condition. Only the Current Maintainer is allowed to
add such statements of exemption to a component of the Work.
104
(a) If a component of this Derived Work can be a direct replacement for a component of the Work when
that component is used with the Base Interpreter, then, wherever this component of the Work
identifies itself to the user when used interactively with that Base Interpreter, the replacement
component of this Derived Work clearly and unambiguously identifies itself as a modified version
of this component to the user when used interactively with that Base Interpreter.
(b) Every component of the Derived Work contains prominent notices detailing the nature of the
changes to that component, or a prominent reference to another file that is distributed as part of
the Derived Work and that contains a complete and accurate log of the changes.
(c) No information in the Derived Work implies that any persons, including (but not limited to) the
authors of the original version of the Work, provide any support, including (but not limited to)
the reporting and handling of errors, to recipients of the Derived Work unless those persons have
stated explicitly that they do provide such support for the Derived Work.
(d) You distribute at least one of the following with the Derived Work:
i. A complete, unmodified copy of the Work; if your distribution of a modified component
is made by offering access to copy the modified component from a designated place, then
offering equivalent access to copy the Work from the same or some similar place meets this
condition, even though third parties are not compelled to copy the Work along with the
modified component;
ii. Information that is sufficient to obtain a complete, unmodified copy of the Work.
7. If you are not the Current Maintainer of the Work, you may distribute a Compiled Work generated
from a Derived Work, as long as the Derived Work is distributed to all recipients of the Compiled
Work, and as long as the conditions of Clause 6, above, are met with regard to the Derived Work.
8. The conditions above are not intended to prohibit, and hence do not apply to, the modification, by
any method, of any component so that it becomes identical to an updated version of that component
of the Work as it is distributed by the Current Maintainer under Clause 4, above.
9. Distribution of the Work or any Derived Work in an alternative format, where the Work or that Derived
Work (in whole or in part) is then produced by applying some process to that format, does not relax
or nullify any sections of this license as they pertain to the results of applying that process.
10. (a) A Derived Work may be distributed under a different license provided that license itself honors
the conditions listed in Clause 6 above, in regard to the Work, though it does not have to honor
the rest of the conditions in this license.
(b) If a Derived Work is distributed under a different license, that Derived Work must provide sufficient documentation as part of itself to allow each recipient of that Derived Work to honor the
restrictions in Clause 6 above, concerning changes from the Work.
11. This license places no restrictions on works that are unrelated to the Work, nor does this license place
any restrictions on aggregating such works with the Work by any means.
12. Nothing in this license is intended to, or may be used to, prevent complete compliance by all parties
with all applicable laws.
9.3.4
No Warranty
There is no warranty for the Work. Except when otherwise stated in writing, the Copyright Holder provides
the Work ‘as is’, without warranty of any kind, either expressed or implied, including, but not limited to,
the implied warranties of merchantability and fitness for a particular purpose. The entire risk as to the
quality and performance of the Work is with you. Should the Work prove defective, you assume the cost of
all necessary servicing, repair, or correction.
In no event unless required by applicable law or agreed to in writing will The Copyright Holder, or
any author named in the components of the Work, or any other party who may distribute and/or modify
the Work as permitted above, be liable to you for damages, including any general, special, incidental or
consequential damages arising out of any use of the Work or out of inability to use the Work (including, but
not limited to, loss of data, data being rendered inaccurate, or losses sustained by anyone as a result of any
failure of the Work to operate with any other programs), even if the Copyright Holder or said author or said
other party has been advised of the possibility of such damages.
105
9.3.5
Maintenance of The Work
The Work has the status ‘author-maintained’ if the Copyright Holder explicitly and prominently states near
the primary copyright notice in the Work that the Work can only be maintained by the Copyright Holder
or simply that it is ‘author-maintained’.
The Work has the status ‘maintained’ if there is a Current Maintainer who has indicated in the Work
that they are willing to receive error reports for the Work (for example, by supplying a valid e-mail address).
It is not required for the Current Maintainer to acknowledge or act upon these error reports.
The Work changes from status ‘maintained’ to ‘unmaintained’ if there is no Current Maintainer, or the
person stated to be Current Maintainer of the work cannot be reached through the indicated means of
communication for a period of six months, and there are no other significant signs of active maintenance.
You can become the Current Maintainer of the Work by agreement with any existing Current Maintainer
to take over this role.
If the Work is unmaintained, you can become the Current Maintainer of the Work through the following
steps:
1. Make a reasonable attempt to trace the Current Maintainer (and the Copyright Holder, if the two
differ) through the means of an Internet or similar search.
2. If this search is successful, then enquire whether the Work is still maintained.
(a) If it is being maintained, then ask the Current Maintainer to update their communication data
within one month.
(b) If the search is unsuccessful or no action to resume active maintenance is taken by the Current Maintainer, then announce within the pertinent community your intention to take over
maintenance. (If the Work is a LATEX work, this could be done, for example, by posting to
comp.text.tex.)
3. (a) If the Current Maintainer is reachable and agrees to pass maintenance of the Work to you, then
this takes effect immediately upon announcement.
(b) If the Current Maintainer is not reachable and the Copyright Holder agrees that maintenance of
the Work be passed to you, then this takes effect immediately upon announcement.
4. If you make an ‘intention announcement’ as described in 2b above and after three months your intention
is challenged neither by the Current Maintainer nor by the Copyright Holder nor by other people, then
you may arrange for the Work to be changed so as to name you as the (new) Current Maintainer.
5. If the previously unreachable Current Maintainer becomes reachable once more within three months of
a change completed under the terms of 3b or 4, then that Current Maintainer must become or remain
the Current Maintainer upon request provided they then update their communication data within one
month.
A change in the Current Maintainer does not, of itself, alter the fact that the Work is distributed under the
lppl license.
If you become the Current Maintainer of the Work, you should immediately provide, within the Work,
a prominent and unambiguous statement of your status as Current Maintainer. You should also announce
your new status to the same pertinent community as in 2b above.
9.3.6
Whether and How to Distribute Works under This License
This section contains important instructions, examples, and recommendations for authors who are considering distributing their works under this license. These authors are addressed as ‘you’ in this section.
9.3.7
Choosing This License or Another License
If for any part of your work you want or need to use distribution conditions that differ significantly from
those in this license, then do not refer to this license anywhere in your work but, instead, distribute your
work under a different license. You may use the text of this license as a model for your own license, but your
license should not refer to the lppl or otherwise give the impression that your work is distributed under the
lppl.
The document ‘modguide.tex’ in the base LATEX distribution explains the motivation behind the conditions of this license. It explains, for example, why distributing LATEX under the gnu General Public
106
License (gpl) was considered inappropriate. Even if your work is unrelated to LATEX, the discussion in
‘modguide.tex’ may still be relevant, and authors intending to distribute their works under any license are
encouraged to read it.
9.3.8
A Recommendation on Modification Without Distribution
It is wise never to modify a component of the Work, even for your own personal use, without also meeting the
above conditions for distributing the modified component. While you might intend that such modifications
will never be distributed, often this will happen by accident – you may forget that you have modified that
component; or it may not occur to you when allowing others to access the modified version that you are
thus distributing it and violating the conditions of this license in ways that could have legal implications
and, worse, cause problems for the community. It is therefore usually in your best interest to keep your copy
of the Work identical with the public one. Many works provide ways to control the behavior of that work
without altering any of its licensed components.
9.3.9
How to Use This License
To use this license, place in each of the components of your work both an explicit copyright notice including
your name and the year the work was authored and/or last substantially modified. Include also a statement
that the distribution and/or modification of that component is constrained by the conditions in this license.
Here is an example of such a notice and statement:
%% pig.dtx
%% Copyright 2005 M. Y. Name
%
% This work may be distributed and/or modified under the
% conditions of the LaTeX Project Public License, either version 1.3
% of this license or (at your option) any later version.
% The latest version of this license is in
%
http://www.latex-project.org/lppl.txt
% and version 1.3 or later is part of all distributions of LaTeX
% version 2005/12/01 or later.
%
% This work has the LPPL maintenance status ‘maintained’.
%
% The Current Maintainer of this work is M. Y. Name.
%
% This work consists of the files pig.dtx and pig.ins
% and the derived file pig.sty.
Given such a notice and statement in a file, the conditions given in this license document would apply,
with the ‘Work’ referring to the three files ‘pig.dtx’, ‘pig.ins’, and ‘pig.sty’ (the last being generated
from ‘pig.dtx’ using ‘pig.ins’), the ‘Base Interpreter’ referring to any ‘LATEX-Format’, and both ‘Copyright
Holder’ and ‘Current Maintainer’ referring to the person ‘M. Y. Name’.
If you do not want the Maintenance section of lppl to apply to your Work, change ‘maintained’ above
into ‘author-maintained’. However, we recommend that you use ‘maintained’ as the Maintenance section
was added in order to ensure that your Work remains useful to the community even when you can no longer
maintain and support it yourself.
9.3.10
Derived Works That Are Not Replacements
Several clauses of the lppl specify means to provide reliability and stability for the user community. They
therefore concern themselves with the case that a Derived Work is intended to be used as a (compatible or
incompatible) replacement of the original Work. If this is not the case (e.g., if a few lines of code are reused
for a completely different task), then clauses 6b and 6d shall not apply.
9.3.11
Important Recommendations
Defining What Constitutes the Work The lppl requires that distributions of the Work contain all
the files of the Work. It is therefore important that you provide a way for the licensee to determine which
107
files constitute the Work. This could, for example, be achieved by explicitly listing all the files of the Work
near the copyright notice of each file or by using a line such as:
% This work consists of all files listed in manifest.txt.
in that place. In the absence of an unequivocal list it might be impossible for the licensee to determine
what is considered by you to comprise the Work and, in such a case, the licensee would be entitled to make
reasonable conjectures as to which files comprise the Work.
9.4
9.4.1
GNU Free Documentation License, Version 1.2, November 2002
Preamble
The purpose of this License is to make a manual, textbook, or other functional and useful document “free”
in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without
modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and
publisher a way to get credit for their work, while not being considered responsible for modifications made
by others.
This License is a kind of “copyleft”, which means that derivative works of the document must themselves
be free in the same sense. It complements the GNU General Public License, which is a copyleft license
designed for free software.
We have designed this License in order to use it for manuals for free software, because free software needs
free documentation: a free program should come with manuals providing the same freedoms that the software
does. But this License is not limited to software manuals; it can be used for any textual work, regardless
of subject matter or whether it is published as a printed book. We recommend this License principally for
works whose purpose is instruction or reference.
9.4.2
Applicability and definitions
This License applies to any manual or other work, in any medium, that contains a notice placed by the
copyright holder saying it can be distributed under the terms of this License. Such a notice grants a
world-wide, royalty-free license, unlimited in duration, to use that work under the conditions stated herein.
The “Document”, below, refers to any such manual or work. Any member of the public is a licensee, and
is addressed as “you”. You accept the license if you copy, modify or distribute the work in a way requiring
permission under copyright law.
A “Modified Version” of the Document means any work containing the Document or a portion of it,
either copied verbatim, or with modifications and/or translated into another language.
A “Secondary Section” is a named appendix or a front-matter section of the Document that deals
exclusively with the relationship of the publishers or authors of the Document to the Document’s overall
subject (or to related matters) and contains nothing that could fall directly within that overall subject.
(Thus, if the Document is in part a textbook of mathematics, a Secondary Section may not explain any
mathematics.) The relationship could be a matter of historical connection with the subject or with related
matters, or of legal, commercial, philosophical, ethical or political position regarding them.
The “Invariant Sections” are certain Secondary Sections whose titles are designated, as being those of
Invariant Sections, in the notice that says that the Document is released under this License. If a section does
not fit the above definition of Secondary then it is not allowed to be designated as Invariant. The Document
may contain zero Invariant Sections. If the Document does not identify any Invariant Sections then there
are none.
The “Cover Texts” are certain short passages of text that are listed, as Front-Cover Texts or Back-Cover
Texts, in the notice that says that the Document is released under this License. A Front-Cover Text may be
at most 5 words, and a Back-Cover Text may be at most 25 words.
A “Transparent” copy of the Document means a machine-readable copy, represented in a format whose
specification is available to the general public, that is suitable for revising the document straightforwardly
with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some
widely available drawing editor, and that is suitable for input to text formatters or for automatic translation
to a variety of formats suitable for input to text formatters. A copy made in an otherwise Transparent
file format whose markup, or absence of markup, has been arranged to thwart or discourage subsequent
modification by readers is not Transparent. An image format is not Transparent if used for any substantial
amount of text. A copy that is not “Transparent” is called “Opaque”.
108
Examples of suitable formats for Transparent copies include plain ASCII without markup, Texinfo input
format, LaTeX input format, SGML or XML using a publicly available DTD, and standard-conforming
simple HTML, PostScript or PDF designed for human modification. Examples of transparent image formats
include PNG, XCF and JPG. Opaque formats include proprietary formats that can be read and edited
only by proprietary word processors, SGML or XML for which the DTD and/or processing tools are not
generally available, and the machine-generated HTML, PostScript or PDF produced by some word processors
for output purposes only.
The “Title Page” means, for a printed book, the title page itself, plus such following pages as are needed
to hold, legibly, the material this License requires to appear in the title page. For works in formats which
do not have any title page as such, “Title Page” means the text near the most prominent appearance of the
work’s title, preceding the beginning of the body of the text.
A section “Entitled XYZ” means a named subunit of the Document whose title either is precisely XYZ or
contains XYZ in parentheses following text that translates XYZ in another language. (Here XYZ stands for a
specific section name mentioned below, such as “Acknowledgements”, “Dedications”, “Endorsements”,
or “History”.) To “Preserve the Title” of such a section when you modify the Document means that it
remains a section “Entitled XYZ” according to this definition.
The Document may include Warranty Disclaimers next to the notice which states that this License applies
to the Document. These Warranty Disclaimers are considered to be included by reference in this License,
but only as regards disclaiming warranties: any other implication that these Warranty Disclaimers may have
is void and has no effect on the meaning of this License.
9.4.3
Verbatim Copying
You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the
Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies
you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a
large enough number of copies you must also follow the conditions in section 3.
You may also lend copies, under the same conditions stated above, and you may publicly display copies.
9.4.4
Copying in Quantity
If you publish printed copies (or copies in media that commonly have printed covers) of the Document,
numbering more than 100, and the Document’s license notice requires Cover Texts, you must enclose the
copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover,
and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the
publisher of these copies. The front cover must present the full title with all words of the title equally
prominent and visible. You may add other material on the covers in addition. Copying with changes limited
to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated
as verbatim copying in other respects.
If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed
(as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages.
If you publish or distribute Opaque copies of the Document numbering more than 100, you must either
include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque
copy a computer-network location from which the general network-using public has access to download using
public-standard network protocols a complete Transparent copy of the Document, free of added material. If
you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque
copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location
until at least one year after the last time you distribute an Opaque copy (directly or through your agents or
retailers) of that edition to the public.
It is requested, but not required, that you contact the authors of the Document well before redistributing
any large number of copies, to give them a chance to provide you with an updated version of the Document.
9.4.5
Modifications
You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and
3 above, provided that you release the Modified Version under precisely this License, with the Modified
109
Version filling the role of the Document, thus licensing distribution and modification of the Modified Version
to whoever possesses a copy of it. In addition, you must do these things in the Modified Version:
A. Use in the Title Page (and on the covers, if any) a title distinct from that of the Document, and
from those of previous versions (which should, if there were any, be listed in the History section of the
Document). You may use the same title as a previous version if the original publisher of that version
gives permission.
B. List on the Title Page, as authors, one or more persons or entities responsible for authorship of
the modifications in the Modified Version, together with at least five of the principal authors of the
Document (all of its principal authors, if it has fewer than five), unless they release you from this
requirement.
C. State on the Title page the name of the publisher of the Modified Version, as the publisher.
D. Preserve all the copyright notices of the Document.
E. Add an appropriate copyright notice for your modifications adjacent to the other copyright notices.
F. Include, immediately after the copyright notices, a license notice giving the public permission to use
the Modified Version under the terms of this License, in the form shown in the Addendum below.
G. Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the
Document’s license notice.
H. Include an unaltered copy of this License.
I. Preserve the section Entitled “History”, Preserve its Title, and add to it an item stating at least the
title, year, new authors, and publisher of the Modified Version as given on the Title Page. If there is no
section Entitled “History” in the Document, create one stating the title, year, authors, and publisher of
the Document as given on its Title Page, then add an item describing the Modified Version as stated
in the previous sentence.
J. Preserve the network location, if any, given in the Document for public access to a Transparent copy
of the Document, and likewise the network locations given in the Document for previous versions it
was based on. These may be placed in the “History” section. You may omit a network location for a
work that was published at least four years before the Document itself, or if the original publisher of
the version it refers to gives permission.
K. For any section Entitled “Acknowledgements” or “Dedications”, Preserve the Title of the section, and
preserve in the section all the substance and tone of each of the contributor acknowledgements and/or
dedications given therein.
L. Preserve all the Invariant Sections of the Document, unaltered in their text and in their titles. Section
numbers or the equivalent are not considered part of the section titles.
M. Delete any section Entitled “Endorsements”. Such a section may not be included in the Modified
Version.
N. Do not retitle any existing section to be Entitled “Endorsements” or to conflict in title with any
Invariant Section.
O. Preserve any Warranty Disclaimers.
If the Modified Version includes new front-matter sections or appendices that qualify as Secondary
Sections and contain no material copied from the Document, you may at your option designate some or all
of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified
Version’s license notice. These titles must be distinct from any other section titles.
You may add a section Entitled “Endorsements”, provided it contains nothing but endorsements of your
Modified Version by various parties–for example, statements of peer review or that the text has been approved
by an organization as the authoritative definition of a standard.
You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words
as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of
Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any
110
one entity. If the Document already includes a cover text for the same cover, previously added by you or by
arrangement made by the same entity you are acting on behalf of, you may not add another; but you may
replace the old one, on explicit permission from the previous publisher that added the old one.
The author(s) and publisher(s) of the Document do not by this License give permission to use their names
for publicity for or to assert or imply endorsement of any Modified Version.
9.4.6
Combining Documents
You may combine the Document with other documents released under this License, under the terms defined
in section 4 above for modified versions, provided that you include in the combination all of the Invariant
Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined
work in its license notice, and that you preserve all their Warranty Disclaimers.
The combined work need only contain one copy of this License, and multiple identical Invariant Sections
may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different
contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of
the original author or publisher of that section if known, or else a unique number. Make the same adjustment
to the section titles in the list of Invariant Sections in the license notice of the combined work.
In the combination, you must combine any sections Entitled “History” in the various original documents,
forming one section Entitled “History”; likewise combine any sections Entitled “Acknowledgements”, and any
sections Entitled “Dedications”. You must delete all sections Entitled “Endorsements”.
9.4.7
Collection of Documents
You may make a collection consisting of the Document and other documents released under this License,
and replace the individual copies of this License in the various documents with a single copy that is included
in the collection, provided that you follow the rules of this License for verbatim copying of each of the
documents in all other respects.
You may extract a single document from such a collection, and distribute it individually under this
License, provided you insert a copy of this License into the extracted document, and follow this License in
all other respects regarding verbatim copying of that document.
9.4.8
Aggregating with independent Works
A compilation of the Document or its derivatives with other separate and independent documents or works,
in or on a volume of a storage or distribution medium, is called an “aggregate” if the copyright resulting from
the compilation is not used to limit the legal rights of the compilation’s users beyond what the individual
works permit. When the Document is included in an aggregate, this License does not apply to the other
works in the aggregate which are not themselves derivative works of the Document.
If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the
Document is less than one half of the entire aggregate, the Document’s Cover Texts may be placed on covers
that bracket the Document within the aggregate, or the electronic equivalent of covers if the Document is
in electronic form. Otherwise they must appear on printed covers that bracket the whole aggregate.
9.4.9
Translation
Translation is considered a kind of modification, so you may distribute translations of the Document under
the terms of section 4. Replacing Invariant Sections with translations requires special permission from
their copyright holders, but you may include translations of some or all Invariant Sections in addition to the
original versions of these Invariant Sections. You may include a translation of this License, and all the license
notices in the Document, and any Warranty Disclaimers, provided that you also include the original English
version of this License and the original versions of those notices and disclaimers. In case of a disagreement
between the translation and the original version of this License or a notice or disclaimer, the original version
will prevail.
If a section in the Document is Entitled “Acknowledgements”, “Dedications”, or “History”, the requirement
(section 4) to Preserve its Title (section 1) will typically require changing the actual title.
9.4.10
Termination
You may not copy, modify, sublicense, or distribute the Document except as expressly provided for under
this License. Any other attempt to copy, modify, sublicense or distribute the Document is void, and will
111
automatically terminate your rights under this License. However, parties who have received copies, or rights,
from you under this License will not have their licenses terminated so long as such parties remain in full
compliance.
9.4.11
Future Revisions of this License
The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License
from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail
to address new problems or concerns. See http://www.gnu.org/copyleft/.
Each version of the License is given a distinguishing version number. If the Document specifies that
a particular numbered version of this License “or any later version” applies to it, you have the option of
following the terms and conditions either of that specified version or of any later version that has been
published (not as a draft) by the Free Software Foundation. If the Document does not specify a version
number of this License, you may choose any version ever published (not as a draft) by the Free Software
Foundation.
9.4.12
Addendum: How to use this License for your documents
To use this License in a document you have written, include a copy of the License in the document and put
the following copyright and license notices just after the title page:
Copyright c year your name. Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License, Version 1.2 or any later
version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover
Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled “GNU
Free Documentation License”.
If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the “with . . . Texts.”
line with this:
with the Invariant Sections being list their titles, with the Front-Cover Texts being list,
and with the Back-Cover Texts being list.
If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those
two alternatives to suit the situation.
If your document contains nontrivial examples of program code, we recommend releasing these examples
in parallel under your choice of free software license, such as the GNU General Public License, to permit
their use in free software.
112
10
Supported Formats
TEX was designed to be a flexible system. This is true both for the input for TEX as well as for the output.
The present section explains which input formats there are and how they are supported by pgf. It also
explains which different output formats can be produced.
10.1
Supported Input Formats: LATEX, Plain TEX, ConTEXt
TEX does not prescribe exactly how your input should be formatted. While it is customary that, say,
an opening brace starts a scope in TEX, this is by no means necessary. Likewise, it is customary that
environments start with \begin, but TEX could not really care less about the exact command name.
Even though TEX can be reconfigured, users can not. For this reason, certain input formats specify a set
of commands and conventions how input for TEX should be formatted. There are currently three “major”
formats: Donald Knuth’s original plain TEX format, Leslie Lamport’s popular LATEX format, and Hans
Hangen’s ConTEXt format.
10.1.1
Using the LATEX Format
Using pgf and Tik Z with the LATEX format is easy: You say \usepackage{pgf} or \usepackage{tikz}.
Usually, that is all you need to do, all configuration will be done automatically and (hopefully) correctly.
The style files used for the LATEX format reside in the subdirectory latex/pgf/ of the pgf-system.
Mainly, what these files do is to include files in the directory generic/pgf. For example, here is the content
of the file latex/pgf/frontends/tikz.sty:
%
%
%
%
%
%
%
%
Copyright 2006 by Till Tantau
This file may be distributed and/or modified
1. under the LaTeX Project Public License and/or
2. under the GNU Public License.
See the file doc/generic/pgf/licenses/LICENSE for more details.
\RequirePackage{pgf,pgffor}
\input{tikz.code.tex}
\endinput
The files in the generic/pgf directory do the actual work.
10.1.2
Using the Plain TEX Format
When using the plain TEX format, you say \input{pgf.tex} or \input{tikz.tex}. Then, instead of
\begin{pgfpicture} and \end{pgfpicture} you use \pgfpicture and \endpgfpicture.
Unlike for the LATEX format, pgf is not as good at discerning the appropriate configuration for the plain
TEX format. In particular, it can only automatically determine the correct output format if you use pdftex
or tex plus dvips. For all other output formats you need to set the macro \pgfsysdriver to the correct
value. See the description of using output formats later on.
Like the LATEX style files, the plain TEX files like tikz.tex also just include the correct tikz.code.tex
file.
10.1.3
Using the ConTEXt Format
When using the ConTEXt format, you say \usemodule[pgf] or \usemodule[tikz]. As for the plain
TEX format you also have to replace the start- and end-of-environment tags as follows: Instead of
\begin{pgfpicture} and \end{pgfpicture} you use \startpgfpicture and \stoppgfpicture; similarly,
instead of \begin{tikzpicture} and \end{tikzpicture} you use must now use \starttikzpicture and
\stoptikzpicture; and so on for other environments.
The ConTEXt support is very similar to the plain TEX support, so the same restrictions apply: You may
have to set the output format directly and graphics inclusion may be a problem.
In addition to pgf and tikz there also exist modules like pgfcore or pgfmodulematrix. To use them,
you may need to include the module pgfmod first (the modules pgf and tikz both include pgfmod for you, so
113
typically you can skip this). This special module is necessary since ConTEXt satanically restricts the length
of module names to 6 characters and pgf’s long names are mapped to cryptic 6-letter-names for you by the
module pgfmod.
10.2
Supported Output Formats
An output format is a format in which TEX outputs the text it has typeset. Producing the output is
(conceptually) a two-stage process:
1. TEX typesets your text and graphics. The result of this typesetting is mainly a long list of letter–
coordinate pairs, plus (possibly) some “special” commands. This long list of pairs is written to something called a .dvi-file (informally known as “device-independent file”).
2. Some other program reads this .dvi-file and translates the letter–coordinate pairs into, say, PostScript
commands for placing the given letter at the given coordinate.
The classical example of this process is the combination of latex and dvips. The latex program (which
is just the tex program called with the LATEX-macros preinstalled) produces a .dvi-file as its output. The
dvips program takes this output and produces a .ps-file (a PostScript file). Possibly, this file is further
converted using, say, ps2pdf, whose name is supposed to mean “PostScript to PDF.” Another example of
programs using this process is the combination of tex and dvipdfm. The dvipdfm program takes a .dvi-file
as input and translates the letter–coordinate pairs therein into pdf-commands, resulting in a .pdf file
directly. Finally, the tex4ht is also a program that takes a .dvi-file and produces an output, this time it
is a .html file. The programs pdftex and pdflatex are special: They directly produce a .pdf-file without
the intermediate .dvi-stage. However, from the programmer’s point of view they behave exactly as if there
was an intermediate stage.
Normally, TEX only produces letter–coordinate pairs as its “output.” This obviously makes it difficult
to draw, say, a curve. For this, “special” commands can be used. Unfortunately, these special commands
are not the same for the different programs that process the .dvi-file. Indeed, every program that takes a
.dvi-file as input has a totally different syntax for the special commands.
One of the main jobs of pgf is to “abstract away” the difference in the syntax of the different programs.
However, this means that support for each program has to be “programmed,” which is a time-consuming and
complicated process.
10.2.1
Selecting the Backend Driver
When TEX typesets your document, it does not know which program you are going to use to transform the
.dvi-file. If your .dvi-file does not contain any special commands, this would be fine; but these days almost
all .dvi-files contain lots of special commands. It is thus necessary to tell TEX which program you are going
to use later on.
Unfortunately, there is no “standard” way of telling this to TEX. For the LATEX format a sophisticated
mechanism exists inside the graphics package and pgf plugs into this mechanism. For other formats and
when this plugging does not work as expected, it is necessary to tell pgf directly which program you are
going to use. This is done by redefining the macro \pgfsysdriver to an appropriate value before you load
pgf. If you are going to use the dvips program, you set this macro to the value pgfsys-dvips.def; if
you use pdftex or pdflatex, you set it to pgfsys-pdftex.def; and so on. In the following, details of the
support of the different programs are discussed.
10.2.2
Producing PDF Output
pgf supports three programs that produce pdf output (pdf means “portable document format” and was
invented by the Adobe company): dvipdfm, pdftex, and vtex. The pdflatex program is the same as the
pdftex program: it uses a different input format, but the output is exactly the same.
File pgfsys-pdftex.def
This is the driver file for use with pdfTEX, that is, with the pdftex or pdflatex command. It includes
pgfsys-common-pdf.def.
This driver has a lot of functionality. (Almost) everything pgf “can do at all” is implemented in this
driver.
114
File pgfsys-dvipdfm.def
This is a driver file for use with (la)tex followed by dvipdfm. It includes pgfsys-common-pdf.def.
This driver supports most of pgf’s features, but there are some restrictions:
1. In LATEX mode it uses graphicx for the graphics inclusion and does not support masking.
2. In plain TEX mode it does not support image inclusion.
File pgfsys-xetex.def
This is a driver file for use with xe(la)tex followed by xdvipdfmx. This driver supports largely the
same operations as the dvipdfm driver.
File pgfsys-vtex.def
This is the driver file for use with the commercial vtex program. Even though it produces pdf output,
it includes pgfsys-common-postscript.def. Note that the vtex program can produce both Postscript
and pdf output, depending on the command line parameters. However, whether you produce Postscript
or pdf output does not change anything with respect to the driver.
This driver supports most of pgf’s features, except for the following restrictions:
1. In LATEX mode it uses graphicx for the graphics inclusion and does not support masking.
2. In plain TEX mode it does not support image inclusion.
3. Shading is fully implemented, but yields the same quality as the implementation for dvips.
4. Opacity is not supported.
5. Remembering of pictures (inter-picture connections) is not supported.
It is also possible to produce a .pdf-file by first producing a PostScript file (see below) and then using a
PostScript-to-pdf conversion program like ps2pdf or the Acrobat Distiller.
10.2.3
Producing PostScript Output
File pgfsys-dvips.def
This is a driver file for use with (la)tex followed by dvips. It includes pgfsys-common-postscript.def.
This driver also supports most of pgf’s features, except for the following restrictions:
1. In LATEX mode it uses graphicx for the graphics inclusion and does not support masking.
2. In plain TEX mode it does not support image inclusion.
3. Shading is fully implemented, but the results will not be as good as with a driver producing .pdf
as output.
4. Opacity works only in conjunction with newer versions of Ghostscript.
5. For remembering of pictures (inter-picture connections) you need to use a recent version of pdftex
running in DVI-mode.
File pgfsys-textures.def
This is a driver file for use with the textures program. It includes pgfsys-common-postscript.def.
This driver has exactly the same restrictions as the driver for dvips.
You can also use the vtex program together with pgfsys-vtex.def to produce Postscript output.
10.2.4
Producing SVG Output
File pgfsys-dvisvgm.def
This driver converts dvi files to svg file, including text and fonts. When you select this driver, pgf will
output the required raw svg code for the pictures it produces.
Since the graphics package does not (yet?) support this driver directly, there is special rule for this
driver in LATEX: If the option dvisvgm is given to the tikz package, this driver gets selected (normally,
the driver selected by graphics would be used). For packages like beamer that load pgf themselves,
this means that the option dvisvgm should be given to the document class.
115
% example.tex
\documentclass[dvisvgm]{minimal}
\usepackage{tikz}
\begin{document}
Hello \tikz [baseline] \fill [fill=blue!80!black] (0,.75ex) circle[radius=.75ex];
\end{document}
And then run
latex example
dvisvgm example
or better
lualatex --output-format=dvi example
dvisvgm example
(This is “better” since it gives you access to the full power of LuaTEX inside your TEX-file. In particular,
Tik Z is able to run graph drawing algorithms in this case.)
Unlike the tex4ht driver below, this driver has full support of text nodes.
File pgfsys-tex4ht.def
This is a driver file for use with the tex4ht program. It is selected automatically when the tex4ht style
or command is loaded. It includes pgfsys-common-svg.def.
The tex4ht program converts .dvi-files to .html-files. While the html-format cannot be used to draw
graphics, the svg-format can. This driver will ask pgf to produce an svg-picture for each pgf graphic
in your text.
When using this driver you should be aware of the following restrictions:
1. In LATEX mode it uses graphicx for the graphics inclusion.
2. In plain TEX mode it does not support image inclusion.
3. Remembering of pictures (inter-picture connections) is not supported.
4. Text inside pgfpictures is not supported very well. The reason is that the svg specification
currently does not support text very well and, although it is possible to “escape back” to html,
Tik Z has then to guess what size the text rendered by the browser would have.
5. Unlike for other output formats, the bounding box of a picture “really crops” the picture.
6. Matrices do not work.
7. Functional shadings are not supported.
The driver basically works as follows: When a {pgfpicture} is started, appropriate \special commands are used to directed the output of tex4ht to a new file called \jobname-xxx.svg, where xxx
is a number that is increased for each graphic. Then, till the end of the picture, each (system layer)
graphic command creates a special that inserts appropriate svg literal text into the output file. The
exact details are a bit complicated since the imaging model and the processing model of PostScript/pdf
and svg are not quite the same; but they are “close enough” for pgf’s purposes.
Because text is not supported very well in the svg standard, you may wish to use the following options
to modify the way text is handled:
(default false)
/pgf/tex4ht node/escape=hbooleani
Selects the rendering method for a text node with the tex4ht driver.
When this key is set to false, text is translated
P R into svg text, which is somewhat limited: simple
characters (letters, numerals, punctuation, , , . . . ), subscripts and superscripts (but not subsubscripts) will display but everything else will be filtered out, ignored or will produce invalid html
code (in the worst case). This means that two kind of texts render reasonably well:
1. First, plain text without math mode, special characters or anything else special.
2. Second, very simple mathematical text that contains subscripts or superscripts. Even then,
variables are not correctly set in italics and, in general, text simple does not look very nice.
116
If you use text that contains anything special, even something as simple as $\alpha$, this may
corrupt the graphic.
\tikz \node[draw,/pgf/tex4ht node/escape=false] {Example : $(a+b)^2=a^2+2ab+b^2$};
When you write node[/pgf/tex4ht node/escape=true] {htexti}, pgf escapes back to html to
render the htexti. This method produces valid html code in most cases and the support for
complicated text nodes is much better since code that renders well outside a {pgfpicture}, should
also render well inside a text node. Another advantage is that inside text nodes with fixed width,
html will produce line breaks for long lines. On the other hand, you need a browser with good svg
support to display the picture. Also, the text will display differently, depending on your browsers,
the fonts you have on your system and your settings. Finally, pgf has to guess the size of the text
rendered by the browser to scale it and prevent it from sticking from the node. When it fails, the
text will be either cropped or too small.
\tikz \node[draw,/pgf/tex4ht node/escape=true]
{Example : $\int_0^\infty\frac{1}{1+t^2}dt=\frac{\pi}{2}$};
(default \jobname)
/pgf/tex4ht node/css=hfilenamei
This option allows you to tell the browser what css file it should use to style the display of the
node (only with tex4ht node/escape=true).
/pgf/tex4ht node/class=hclass namei
(default foreignobject)
This option allows you to give a class name to the node, allowing it to be styled by a css file (only
with tex4ht node/escape=true).
/pgf/tex4ht node/id=hid namei
(default \jobname picturenumber-nodenumber)
This option allows you to give a unique id to the node, allowing it to be styled by a css file (only
with tex4ht node/escape=true).
10.2.5
Producing Perfectly Portable DVI Output
File pgfsys-dvi.def
This is a driver file that can be used with any output driver, except for tex4ht.
The driver will produce perfectly portable .dvi files by composing all pictures entirely of black rectangles, the basic and only graphic shape supported by the TEX core. Even straight, but slanted lines are
tricky to get right in this model (they need to be composed of lots of little squares).
Naturally, very little is possible with this driver. In fact, so little is possible that it is easier to list what
is possible:
• Text boxes can be placed in the normal way.
• Lines and curves can be drawn (stroked). If they are not horizontal or vertical, they are composed
of hundreds of small rectangles.
• Lines of different width are supported.
• Transformations are supported.
Note that, say, even filling is not supported! (Let alone color or anything fancy.)
This driver has only one real application: It might be useful when you only need horizontal or vertical
lines in a picture. Then, the results are quite satisfactory.
117
Part III
Tik Z ist kein Zeichenprogramm
by Till Tantau
F
D
δ
C
α
β
γ
When we assume that AB and CD
are parallel, i. e., AB k CD, then α = δ
and β = γ.
B
A
E
\begin{tikzpicture}[angle radius=.75cm]
\node
\node
\node
\node
\node
\node
(A)
(B)
(C)
(D)
(E)
(F)
at
at
at
at
at
at
(-2,0)
[red,left]
{$A$};
( 3,.5)
[red,right] {$B$};
(-2,2) [blue,left] {$C$};
( 3,2.5) [blue,right] {$D$};
(60:-5mm) [below]
{$E$};
(60:3.5cm) [above]
{$F$};
\coordinate (X) at (intersection cs:first line={(A)--(B)}, second line={(E)--(F)});
\coordinate (Y) at (intersection cs:first line={(C)--(D)}, second line={(E)--(F)});
\path
(A) edge [red, thick] (B)
(C) edge [blue, thick] (D)
(E) edge [thick]
(F)
pic ["$\alpha$", draw, fill=yellow]
pic ["$\beta$",
draw, fill=green!30]
pic ["$\gamma$", draw, fill=yellow]
pic ["$\delta$", draw, fill=green!30]
{angle
{angle
{angle
{angle
=
=
=
=
F--X--A}
B--X--F}
E--Y--D}
C--Y--E};
\node at ($ (D)!.5!(B) $) [right=1cm,text width=6cm,rounded corners,fill=red!20,inner sep=1ex]
{
When we assume that $\color{red}AB$ and $\color{blue}CD$ are
parallel, i.\,e., ${\color{red}AB} \mathbin{\|} \color{blue}CD$,
then $\alpha = \delta$ and $\beta = \gamma$.
};
\end{tikzpicture}
118
11
Design Principles
This section describes the design principles behind the Tik Z frontend, where Tik Z means “Tik Z ist kein
Zeichenprogramm.” To use Tik Z, as a LATEX user say \usepackage{tikz} somewhere in the preamble, as
a plain TEX user say \input tikz.tex. Tik Z’s job is to make your life easier by providing an easy-to-learn
and easy-to-use syntax for describing graphics.
The commands and syntax of Tik Z were influenced by several sources. The basic command names and the
notion of path operations is taken from metafont, the option mechanism comes from pstricks, the notion
of styles is reminiscent of svg, the graph syntax is taken from graphviz. To make it all work together,
some compromises were necessary. I also added some ideas of my own, like coordinate transformations.
The following basic design principles underlie Tik Z:
1. Special syntax for specifying points.
2. Special syntax for path specifications.
3. Actions on paths.
4. Key-value syntax for graphic parameters.
5. Special syntax for nodes.
6. Special syntax for trees.
7. Special syntax for graphs.
8. Grouping of graphic parameters.
9. Coordinate transformation system.
11.1
Special Syntax For Specifying Points
Tik Z provides a special syntax for specifying points and coordinates. In the simplest case, you provide two
TEX dimensions, separated by commas, in round brackets as in (1cm,2pt).
You can also specify a point in polar coordinates by using a colon instead of a comma as in (30:1cm),
which means “1cm in a 30 degrees direction.”
If you do not provide a unit, as in (2,1), you specify a point in pgf’s xy-coordinate system. By default,
the unit x-vector goes 1cm to the right and the unit y-vector goes 1cm upward.
By specifying three numbers as in (1,1,1) you specify a point in pgf’s xyz-coordinate system.
It is also possible to use an anchor of a previously defined shape as in (first node.south).
You can add two plus signs before a coordinate as in ++(1cm,0pt). This means “1cm to the right of
the last point used.” This allows you to easily specify relative movements. For example, (1,0) ++(1,0)
++(0,1) specifies the three coordinates (1,0), then (2,0), and (2,1).
Finally, instead of two plus signs, you can also add a single one. This also specifies a point in a relative
manner, but it does not “change” the current point used in subsequent relative commands. For example,
(1,0) +(1,0) +(0,1) specifies the three coordinates (1,0), then (2,0), and (1,1).
11.2
Special Syntax For Path Specifications
When creating a picture using Tik Z, your main job is the specification of paths. A path is a series of straight
or curved lines, which need not be connected. Tik Z makes it easy to specify paths, partly using the syntax
of metapost. For example, to specify a triangular path you use
(5pt,0pt) -- (0pt,0pt) -- (0pt,5pt) -- cycle
and you get
when you draw this path.
119
11.3
Actions on Paths
A path is just a series of straight and curved lines, but it is not yet specified what should happen with it.
One can draw a path, fill a path, shade it, clip it, or do any combination of these. Drawing (also known
as stroking) can be thought of as taking a pen of a certain thickness and moving it along the path, thereby
drawing on the canvas. Filling means that the interior of the path is filled with a uniform color. Obviously,
filling makes sense only for closed paths and a path is automatically closed prior to filling, if necessary.
Given a path as in \path (0,0) rectangle (2ex,1ex);, you can draw it by adding the draw option as in
\path[draw] (0,0) rectangle (2ex,1ex);, which yields . The \draw command is just an abbreviation
for \path[draw]. To fill a path, use the fill option or the \fill command, which is an abbreviation for
\path[fill]. The \filldraw command is an abbreviation for \path[fill,draw]. Shading is caused by
the shade option (there are \shade and \shadedraw abbreviations) and clipping by the clip option. There
is also a \clip command, which does the same as \path[clip], but not commands like \drawclip. Use,
say, \draw[clip] or \path[draw,clip] instead.
All of these commands can only be used inside {tikzpicture} environments.
Tik Z allows you to use different colors for filling and stroking.
11.4
Key-Value Syntax for Graphic Parameters
Whenever Tik Z draws or fills a path, a large number of graphic parameters influences the rendering. Examples include the colors used, the dashing pattern, the clipping area, the line width, and many others. In
Tik Z, all these options are specified as lists of so called key-value pairs, as in color=red, that are passed
as optional parameters to the path drawing and filling commands. This usage is similar to pstricks. For
example, the following will draw a thick, red triangle;
\tikz \draw[line width=2pt,color=red] (1,0) -- (0,0) -- (0,1) -- cycle;
11.5
Special Syntax for Specifying Nodes
Tik Z introduces a special syntax for adding text or, more generally, nodes to a graphic. When you specify
a path, add nodes as in the following example:
\tikz \draw (1,1) node {text} -- (2,2);
text
Nodes are inserted at the current position of the path, but either after (the default) or before the complete
path is rendered. When special options are given, as in \draw (1,1) node[circle,draw] {text};, the
text is not just put at the current position. Rather, it is surrounded by a circle and this circle is “drawn.”
You can add a name to a node for later reference either by using the option name=hnode namei or by
stating the node name in parentheses outside the text as in node[circle](name){text}.
Predefined shapes include rectangle, circle, and ellipse, but it is possible (though a bit challenging)
to define new shapes.
11.6
Special Syntax for Specifying Trees
The “node syntax” can also be used to draw tress: A node can be followed by any number of children, each
introduced by the keyword child. The children are nodes themselves, each of which may have children in
turn.
root
left
right
child child
\begin{tikzpicture}
\node {root}
child {node {left}}
child {node {right}
child {node {child}}
child {node {child}}
};
\end{tikzpicture}
120
Since trees are made up from nodes, it is possible to use options to modify the way trees are drawn. Here
are two examples of the above tree, redrawn with different options:
root
right
left
child
child
child
right
root
child
left
11.7
\begin{tikzpicture}
[edge from parent fork down, sibling distance=15mm, level distance=15mm,
every node/.style={fill=red!30,rounded corners},
edge from parent/.style={red,-o,thick,draw}]
\node {root}
child {node {left}}
child {node {right}
child {node {child}}
child {node {child}}
};
\end{tikzpicture}
\begin{tikzpicture}
[parent anchor=east,child anchor=west,grow=east,
sibling distance=15mm, level distance=15mm,
every node/.style={ball color=red,circle,text=white},
edge from parent/.style={draw,dashed,thick,red}]
\node {root}
child {node {left}}
child {node {right}
child {node {child}}
child {node {child}}
};
\end{tikzpicture}
Special Syntax for Graphs
The \node command gives you fine control over where nodes should be placed, what text they should use,
and what they should look like. However, when you draw a graph, you typically need to create numerous
fairly similar nodes that only differ with respect to the name they show. In these cases, the graph syntax
can be used, which is another syntax layer build “on top” of the node syntax.
\tikz \graph [grow down, branch right] {
root -> { left, right -> {child, child} }
};
root
left
right
child
The syntax of the graph command extends the so-called dot-notation used in the popular graphviz
program.
Depending on the version of TEX you use (it must allow you to call Lua code, which is the case for
LuaTEX), you can also ask Tik Z to do automatically compute good positions for the nodes of a graph using
one of several integrated graph drawing algorithms.
11.8
Grouping of Graphic Parameters
Graphic parameters should often apply to several path drawing or filling commands. For example, we
may wish to draw numerous lines all with the same line width of 1pt. For this, we put these commands
in a {scope} environment that takes the desired graphic options as an optional parameter. Naturally,
the specified graphic parameters apply only to the drawing and filling commands inside the environment.
Furthermore, nested {scope} environments or individual drawing commands can override the graphic parameters of outer {scope} environments. In the following example, three red lines, two green lines, and one
blue line are drawn:
121
\begin{tikzpicture}
\begin{scope}[color=red]
\draw (0mm,10mm) -- (10mm,10mm);
\draw (0mm, 8mm) -- (10mm, 8mm);
\draw (0mm, 6mm) -- (10mm, 6mm);
\end{scope}
\begin{scope}[color=green]
\draw
(0mm, 4mm) -- (10mm, 4mm);
\draw
(0mm, 2mm) -- (10mm, 2mm);
\draw[color=blue] (0mm, 0mm) -- (10mm, 0mm);
\end{scope}
\end{tikzpicture}
The {tikzpicture} environment itself also behaves like a {scope} environment, that is, you can specify
graphic parameters using an optional argument. These optional apply to all commands in the picture.
11.9
Coordinate Transformation System
Tik Z supports both pgf’s coordinate transformation system to perform transformations as well as canvas
transformations, a more low-level transformation system. (For details on the difference between coordinate
transformations and canvas transformations see Section 94.4.)
The syntax is set up in such a way that it is harder to use canvas transformations than coordinate
transformations. There are two reasons for this: First, the canvas transformation must be used with great
care and often results in “bad” graphics with changing line width and text in wrong sizes. Second, pgf loses
track of where nodes and shapes are positioned when canvas transformations are used. So, in almost all
circumstances, you should use coordinate transformations rather than canvas transformations.
122
12
Hierarchical Structures:
Package, Environments, Scopes, and Styles
The present section explains how your files should be structured when you use Tik Z. On the top level,
you need to include the tikz package. In the main text, each graphic needs to be put in a {tikzpicture}
environment. Inside these environments, you can use {scope} environments to create internal groups. Inside
the scopes you use \path commands to actually draw something. On all levels (except for the package level),
graphic options can be given that apply to everything within the environment.
12.1
Loading the Package and the Libraries
\usepackage{tikz} % LATEX
\input tikz.tex
% plain TEX
\usemodule[tikz] % ConTEXt
This package does not have any options.
This will automatically load the pgf and the pgffor package.
pgf needs to know what TEX driver you are intending to use. In most cases pgf is clever enough to
determine the correct driver for you; this is true in particular if you use LATEX. One situation where
pgf cannot know the driver “by itself” is when you use plain TEX or ConTEXt together with dvipdfm.
In this case, you have to write \def\pgfsysdriver{pgfsys-dvipdfm.def} before you input tikz.tex.
\usetikzlibrary{hlist of librariesi}
Once Tik Z has been loaded, you can use this command to load further libraries. The list of libraries
should contain the names of libraries separated by commas. Instead of curly braces, you can also use
square brackets, which is something ConTEXt users will like. If you try to load a library a second time,
nothing will happen.
Example: \usetikzlibrary{arrows.meta}
The above command will load a whole bunch of extra arrow tip definitions.
What this command does is to load the file tikzlibraryhlibraryi.code.tex for each hlibraryi in the
hlist of librariesi. If this file does not exist, the file pgflibraryhlibraryi.code.tex is loaded instead. If
this file also does not exist, an error message is printed. Thus, to write your own library file, all you
need to do is to place a file of the appropriate name somewhere where TEX can find it. LATEX, plain
TEX, and ConTEXt users can then use your library.
12.2
12.2.1
Creating a Picture
Creating a Picture Using an Environment
The “outermost” scope of Tik Z is the {tikzpicture} environment. You may give drawing commands only
inside this environment, giving them outside (as is possible in many other packages) will result in chaos.
In Tik Z, the way graphics are rendered is strongly influenced by graphic options. For example, there
is an option for setting the color used for drawing, another for setting the color used for filling, and also
more obscure ones like the option for setting the prefix used in the filenames of temporary files written while
plotting functions using an external program. The graphic options are specified in key lists, see Section 12.4
below for details. All graphic options are local to the {tikzpicture} to which they apply.
\begin{tikzpicture}[hoptionsi]
henvironment contentsi
\end{tikzpicture}
All Tik Z commands should be given inside this environment, except for the \tikzset command. Unlike
other packages, it is not possible to use, say, \pgfpathmoveto outside this environment and doing so
will result in chaos. For Tik Z, commands like \path are only defined inside this environment, so there
is little chance that you will do something wrong here.
When this environment is encountered, the hoptionsi are parsed, see Section 12.4. All options given
here will apply to the whole picture.
Next, the contents of the environment is processed and the graphic commands therein are put into a
box. Non-graphic text is suppressed as well as possible, but non-pgf commands inside a {tikzpicture}
123
environment should not produce any “output” since this may totally scramble the positioning system
of the backend drivers. The suppressing of normal text, by the way, is done by temporarily switching
the font to \nullfont. You can, however, “escape back” to normal TEX typesetting. This happens, for
example, when you specify a node.
At the end of the environment, pgf tries to make a good guess at the size of a bounding box of the
graphic and then resizes the picture box such that the box has this size. To “make its guess,” everytime
pgf encounters a coordinate, it updates the bounding box’s size such that it encompasses all these
coordinates. This will usually give a good approximation of the bounding box, but will not always be
accurate. First, the line thickness of diagonal lines is not taken into account correctly. Second, control
points of a curve often lie far “outside” the curve and make the bounding box too large. In this case,
you should use the [use as bounding box] option.
The following key influences the baseline of the resulting picture:
/tikz/baseline=hdimension or coordinate or default i
(default 0pt)
Normally, the lower end of the picture is put on the baseline of the surrounding text. For example,
when you give the code \tikz\draw(0,0)circle(.5ex);, pgf will find out that the lower end of
the picture is at −.5ex − 0.2pt (the 0.2pt are half the line width, which is 0.4pt) and that the upper
end is at .5ex + .5pt. Then, the lower end will be put on the baseline, resulting in the following: .
Using this option, you can specify that the picture should be raised or lowered such that the height
hdimensioni is on the baseline. For example, \tikz[baseline=0pt]\draw(0,0)circle(.5ex);
yields since, now, the baseline is on the height of the x-axis.
This options is often useful for “inlined” graphics as in
A
B
$A \mathbin{\tikz[baseline] \draw[-»] (0pt,.5ex) -- (3ex,.5ex);} B$
Instead of a hdimensioni you can also provide a coordinate in parentheses. Then the effect is to
put the baseline on the y-coordinate that the given hcoordinatei has at the end of the picture. This
means that, at the end of the picture, the hcoordinatei is evaluated and then the baseline is set to
the y-coordinate of the resulting point. This makes it easy to reference the y-coordinate of, say,
the baseline of nodes.
Hello world.
Top align:
Hello
\tikz[baseline=(X.base)]
\node [cross out,draw] (X) {world.};
Top align:
\tikz[baseline=(current bounding box.north)]
\draw (0,0) rectangle (1cm,1ex);
Use baseline=default to reset the baseline option to its initial configuration.
(no default)
/tikz/execute at begin picture=hcodei
This option causes hcodei to be executed at the beginning of the picture. This option must be given
in the argument of the {tikzpicture} environment itself since this option will not have an effect
otherwise. After all, the picture has already “started” later on. The effect of multiply setting this
option accumulates.
This option is mainly used in styles like the every picture style to execute certain code at the
start of a picture.
(no default)
/tikz/execute at end picture=hcodei
This option installs hcodei that will be executed at the end of the picture. Using this option multiple
times will cause the code to accumulate. This option must also be given in the optional argument
of the {tikzpicture} environment.
124
Y
X
\begin{tikzpicture}[execute at end picture=%
{
\begin{pgfonlayer}{background}
\path[fill=yellow,rounded corners]
(current bounding box.south west) rectangle
(current bounding box.north east);
\end{pgfonlayer}
}]
\node at (0,0) {X};
\node at (2,1) {Y};
\end{tikzpicture}
All options “end” at the end of the picture. To set an option “globally” change the following style:
(style, initially empty)
/tikz/every picture
This style is installed at the beginning of each picture.
\tikzset{every picture/.style=semithick}
Note that you should not use \tikzset to set options directly. For instance, if you want to use a
line width of 1pt by default, do not try to say \tikzset{line width=1pt} at the beginning of your
document. This will not work since the line width is changed in many places. Instead, say
\tikzset{every picture/.style={line width=1pt}}
This will have the desired effect.
In other TEX formats, you should use the following commands instead:
\tikzpicture[hoptionsi]
henvironment contentsi
\endtikzpicture
This is the plain TEX version of the environment.
\starttikzpicture[hoptionsi]
henvironment contentsi
\stoptikzpicture
This is the ConTEXt version of the environment.
12.2.2
Creating a Picture Using a Command
The following command is an alternative to {tikzpicture} that is particular useful for graphics consisting
of a single or few commands.
\tikz[hoptionsi]{hpath commandsi}
This command places the hpath commandsi inside a {tikzpicture} environment. The hpath commandsi
may contain paragraphs and fragile material (like verbatim text).
If there is only one path command, it need not be surrounded by curly braces, if there are several,
you need to add them (this is similar to the \foreach statement and also to the rules in programming
languages like Java or C concerning the placement of curly braces).
Example: \tikz{\draw (0,0) rectangle (2ex,1ex);} yields
Example: \tikz \draw (0,0) rectangle (2ex,1ex); yields
12.2.3
Handling Catcodes and the Babel Package
Inside a Tik Z picture, most symbols need to have the category code 12 (normal text) in order to ensure that
the parser works properly. This is typically not the case when packages like babel are used, which change
catcodes aggressively.
To solve this problem, Tik Z provides a small library also called babel (which can, however, also be used
together with any other package that globally changes category codes). What it does is to reset the category
codes at the beginning of every {tikzpicture} and to restore them at the beginning of every node. In
125
almost all cases, this is exactly would you would expect and need, so I recommend to always load this library
by saying \usetikzlibrary{babel}. For details on what, exactly, happens with the category codes, see
Section 42.
12.2.4
Adding a Background
By default, pictures do not have any background, that is, they are “transparent” on all parts on which you
do not draw anything. You may instead wish to have a colored background behind your picture or a black
frame around it or lines above and below it or some other kind of decoration.
Since backgrounds are often not needed at all, the definition of styles for adding backgrounds has been
put in the library package backgrounds. This package is documented in Section 43.
12.3
Using Scopes to Structure a Picture
Inside a {tikzpicture} environment you can create scopes using the {scope} environment. This environment is available only inside the {tikzpicture} environment, so once more, there is little chance of doing
anything wrong.
12.3.1
The Scope Environment
\begin{scope}[hoptionsi]
henvironment contentsi
\end{scope}
All hoptionsi are local to the henvironment contentsi. Furthermore, the clipping path is also local to
the environment, that is, any clipping done inside the environment “ends” at its end.
\begin{tikzpicture}[ultra thick]
\begin{scope}[red]
\draw (0mm,10mm) -- (10mm,10mm);
\draw (0mm,8mm) -- (10mm,8mm);
\end{scope}
\draw (0mm,6mm) -- (10mm,6mm);
\begin{scope}[green]
\draw (0mm,4mm) -- (10mm,4mm);
\draw (0mm,2mm) -- (10mm,2mm);
\draw[blue] (0mm,0mm) -- (10mm,0mm);
\end{scope}
\end{tikzpicture}
The following style influences scopes:
(style, initially empty)
/tikz/every scope
This style is installed at the beginning of every scope.
The following options are useful for scopes:
(no default)
/tikz/execute at begin scope=hcodei
This option install some code that will be executed at the beginning of the scope. This option must
be given in the argument of the {scope} environment.
The effect applies only to the current scope, not to subscopes.
(no default)
/tikz/execute at end scope=hcodei
This option installs some code that will be executed at the end of the current scope. Using this
option multiple times will cause the code to accumulate. This option must also be given in the
optional argument of the {scope} environment.
Again, the effect applies only to the current scope, not to subscopes.
\scope[hoptionsi]
henvironment contentsi
\endscope
Plain TEX version of the environment.
126
\startscope[hoptionsi]
henvironment contentsi
\stopscope
ConTEXt version of the environment.
12.3.2
Shorthand for Scope Environments
There is a small library that makes using scopes a bit easier:
Tik Z Library scopes
\usetikzlibrary{scopes} % LATEX and plain TEX
\usetikzlibrary[scopes] % ConTEXt
This library defines a shorthand for starting and ending {scope} environments.
When this library is loaded, the following happens: At certain places inside a Tik Z picture, it is allowed to
start a scope just using a single brace, provided the single brace is followed by options in square brackets:
\begin{tikzpicture}
{ [ultra thick]
{ [red]
\draw (0mm,10mm) -- (10mm,10mm);
\draw (0mm,8mm) -- (10mm,8mm);
}
\draw (0mm,6mm) -- (10mm,6mm);
}
{ [green]
\draw (0mm,4mm) -- (10mm,4mm);
\draw (0mm,2mm) -- (10mm,2mm);
\draw[blue] (0mm,0mm) -- (10mm,0mm);
}
\end{tikzpicture}
In the above example, { [thick] actually causes a \begin{scope}[thick] to be inserted, and the
corresponding closing } causes an \end{scope} to be inserted.
The “certain places” where an opening brace has this special meaning are the following: First, right after
the semicolon that ends a path. Second, right after the end of a scope. Third, right at the beginning of a
scope, which includes the beginning of a picture. Also note that some square bracket must follow, otherwise
the brace is treated as a normal TEX scope.
12.3.3
Single Command Scopes
In some situations it is useful to create a scope for a single command. For instance, when you wish to use
algorithm graph drawing in order to layout a tree, the path of the tree needs to be surrounded by a scope
whose only purpose is to take a key that selects a layout for the scope. Similarly, in order to put something
on a background layer, a scope needs to be created. In such cases, where it will cumbersome to create a
\begin{scope} and \end{scope} pair just for a single command, the \scoped command may be useful:
\scoped[hoptionsi]hpath command i
This command works like \tikz, only you can use it inside a {tikzpicture}. It will take the following
hpath command i and put it inside a {scope} with the hoptionsi set. The hpath command i may either
be a single command ended by a semicolon or it may contain multiple commands, but then they must
be surrounded by curly braces.
Hello world
\begin{tikzpicture}
\node [fill=white] at (1,1) {Hello world};
\scoped [on background layer]
\draw (0,0) grid (3,2);
\end{tikzpicture}
127
12.3.4
Using Scopes Inside Paths
The \path command, which is described in much more detail in later sections, also takes graphic options.
These options are local to the path. Furthermore, it is possible to create local scopes within a path simply
by using curly braces as in
\tikz \draw (0,0) -- (1,1)
{[rounded corners] -- (2,0) -- (3,1)}
-- (3,0) -- (2,1);
Note that many options apply only to the path as a whole and cannot be scoped in this way. For example,
it is not possible to scope the color of the path. See the explanations in the section on paths for more details.
Finally, certain elements that you specify in the argument to the \path command also take local options.
For example, a node specification takes options. In this case, the options apply only to the node, not to the
surrounding path.
12.4
Using Graphic Options
12.4.1
How Graphic Options Are Processed
Many commands and environments of Tik Z accept options. These options are so-called key lists. To process
the options, the following command is used, which you can also call yourself. Note that it is usually better
not to call this command directly, since this will ensure that the effect of options are local to a well-defined
scope.
\tikzset{hoptionsi}
This command will process the hoptionsi using the \pgfkeys command, documented in detail in Section 82, with the default path set to /tikz. Under normal circumstances, the hoptionsi will be lists of
comma-separated pairs of the form hkeyi=hvaluei, but more fancy things can happen when you use the
power of the pgfkeys mechanism, see Section 82 once more.
When a pair hkeyi=hvaluei is processed, the following happens:
1. If the hkeyi is a full key (starts with a slash) it is handled directly as described in Section 82.
2. Otherwise (which is usually the case), it is checked whether /tikz/hkeyi is a key and, if so, it is
executed.
3. Otherwise, it is checked whether /pgf/hkeyi is a key and, if so, it is executed.
4. Otherwise, it is checked whether hkeyi is a color and, if so, color=hkeyi is executed.
5. Otherwise, it is checked whether hkeyi contains a dash and, if so, arrows=hkeyi is executed.
6. Otherwise, it is checked whether hkeyi is the name of a shape and, if so, shape=hkeyi is executed.
7. Otherwise, an error message is printed.
Note that by the above description, all keys starting with /tikz and also all keys starting with /pgf
can be used as hkeyis in an hoptionsi list.
12.4.2
Using Styles to Manage How Pictures Look
There is a way of organizing sets of graphic options “orthogonally” to the normal scoping mechanism. For
example, you might wish all your “help lines” to be drawn in a certain way like, say, gray and thin (do not
dash them, that distracts). For this, you can use styles.
A style is a key that, when used, causes a set of graphic options to be processed. Once a style has been
defined, it can be used like any other key. For example, the predefined help lines style, which you should
use for lines in the background like grid lines or construction lines.
\begin{tikzpicture}
\draw
(0,0) grid +(2,2);
\draw[help lines] (2,0) grid +(2,2);
\end{tikzpicture}
128
Defining styles is also done using options. Suppose we wish to define a style called my style and when
this style is used, we want the draw color to be set to red and the fill color be set to red!20. To achieve
this, we use the following option:
my style/.style={draw=red,fill=red!20}
The meaning of the curious /.style is the following: “The key my style should not be used here but,
rather, be defined. So, set up things such that using the key my style will, in the following, have the same
effect as if we had written draw=red,fill=red!20 instead.”
Returning to the help lines example, suppose we prefer blue help lines. This could be achieved as
follows:
\begin{tikzpicture}[help lines/.style={blue!50,very thin}]
\draw
(0,0) grid +(2,2);
\draw[help lines] (2,0) grid +(2,2);
\end{tikzpicture}
Naturally, one of the main ideas behind styles is that they can be used in different pictures. In this case,
we have to use the \tikzset command somewhere at the beginning.
\tikzset{help lines/.style={blue!50,very thin}}
% ...
\begin{tikzpicture}
\draw
(0,0) grid +(2,2);
\draw[help lines] (2,0) grid +(2,2);
\end{tikzpicture}
Since styles are just special cases of pgfkeys’s general style facility, you can actually do quite a bit more.
Let us start with adding options to an already existing style. This is done using /.append style instead of
/.style:
\begin{tikzpicture}[help lines/.append style=blue!50]
\draw
(0,0) grid +(2,2);
\draw[help lines] (2,0) grid +(2,2);
\end{tikzpicture}
In the above example, the option blue!50 is appended to the style help lines, which now has the same
effect as black!50,very thin,blue!50. Note that two colors are set, so the last one will “win.” There also
exists a handler called /.prefix style that adds something at the beginning of the style.
Just as normal keys, styles can be parameterized. This means that you write hstylei=hvaluei when you
use the style instead of just hstylei. In this case, all occurrences of #1 in hstylei are replaced by hvaluei.
Here is an example that shows how this can be used.
red
blue
\begin{tikzpicture}[outline/.style={draw=#1,thick,fill=#1!50}]
\node [outline=red] at (0,1) {red};
\node [outline=blue] at (0,0) {blue};
\end{tikzpicture}
For parameterized styles you can also set a default value using the /.default handler:
default
blue
\begin{tikzpicture}[outline/.style={draw=#1,thick,fill=#1!50},
outline/.default=black]
\node [outline]
at (0,1) {default};
\node [outline=blue] at (0,0) {blue};
\end{tikzpicture}
For more details on using and setting styles, see also Section 82.
129
13
Specifying Coordinates
13.1
Overview
A coordinate is a position on the canvas on which your picture is drawn. Tik Z uses a special syntax for specifying coordinates. Coordinates are always put in round brackets. The general syntax is ([hoptionsi]hcoordinate
specificationi).
The hcoordinate specificationi specifies coordinates using one of many different possible coordinate systems. Examples are the Cartesian coordinate system or polar coordinates or spherical coordinates. No
matter which coordinate system is used, in the end, a specific point on the canvas is represented by the
coordinate.
There are two ways of specifying which coordinate system should be used:
Explicitly You can specify the coordinate system explicitly. To do so, you give the name of the coordinate system at the beginning, followed by cs:, which stands for “coordinate system,” followed by a
specification of the coordinate using the key-value syntax. Thus, the general syntax for hcoordinate
specificationi in the explicit case is (hcoordinate systemi cs:hlist of key-value pairs specific to the
coordinate systemi).
Implicitly The explicit specification is often too verbose when numerous coordinates should be given.
Because of this, for the coordinate systems that you are likely to use often a special syntax is provided.
Tik Z will notice when you use a coordinate specified in a special syntax and will choose the correct
coordinate system automatically.
Here is an example in which explicit the coordinate systems are specified explicitly:
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw (canvas cs:x=0cm,y=2mm)
-- (canvas polar cs:radius=2cm,angle=30);
\end{tikzpicture}
In the next example, the coordinate systems are implicit:
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw (0cm,2mm) -- (30:2cm);
\end{tikzpicture}
It is possible to give options that apply only to a single coordinate, although this makes sense for
transformation options only. To give transformation options for a single coordinate, give these options at
the beginning in brackets:
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (1,1);
\draw[red] (0,0) -- ([xshift=3pt] 1,1);
\draw
(1,0) -- +(30:2cm);
\draw[red] (1,0) -- +([shift=(135:5pt)] 30:2cm);
\end{tikzpicture}
13.2
13.2.1
Coordinate Systems
Canvas, XYZ, and Polar Coordinate Systems
Let us start with the basic coordinate systems.
Coordinate system canvas
The simplest way of specifying a coordinate is to use the canvas coordinate system. You provide a
dimension dx using the x= option and another dimension dy using the y= option. The position on the
canvas is located at the position that is dx to the right and dy above the origin.
130
(no default, initially 0pt)
/tikz/cs/x=hdimensioni
Distance by which the coordinate is to the right of the origin. You can also write things like 1cm+2pt
since the mathematical engine is used to evaluate the hdimensioni.
(no default, initially 0pt)
/tikz/cs/y=hdimensioni
Distance by which the coordinate is above the origin.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\fill (canvas cs:x=1cm,y=1.5cm)
circle (2pt);
\fill (canvas cs:x=2cm,y=-5mm+2pt) circle (2pt);
\end{tikzpicture}
To specify a coordinate in the coordinate system implicitly, you use two dimensions that are separated
by a comma as in (0cm,3pt) or (2cm,\textheight).
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\fill (1cm,1.5cm)
circle (2pt);
\fill (2cm,-5mm+2pt) circle (2pt);
\end{tikzpicture}
Coordinate system xyz
The xyz coordinate system allows you to specify a point as a multiple of three vectors called the
x-, y-, and z-vectors. By default, the x-vector points 1cm to the right, the y-vector points 1cm upwards, but this can be changed arbitrarily as explained in Section 25.2. The default z-vector points to
−3.85mm, −3.85mm .
To specify the factors by which the vectors should be multiplied before being added, you use the following
three options:
/tikz/cs/x=hfactor i
(no default, initially 0)
Factor by which the x-vector is multiplied.
/tikz/cs/y=hfactor i
(no default, initially 0)
Works like x.
/tikz/cs/z=hfactor i
Works like x.
(no default, initially 0)
\begin{tikzpicture}[->]
\draw (0,0) -- (xyz cs:x=1);
\draw (0,0) -- (xyz cs:y=1);
\draw (0,0) -- (xyz cs:z=1);
\end{tikzpicture}
This coordinate system can also be selected implicitly. To do so, you just provide two or three commaseparated factors (not dimensions).
\begin{tikzpicture}[->]
\draw (0,0) -- (1,0);
\draw (0,0) -- (0,1,0);
\draw (0,0) -- (0,0,1);
\end{tikzpicture}
Note: It is possible to use coordinates like (1,2cm), which are neither canvas coordinates nor xyz
coordinates. The rule is the following: If a coordinate is of the implicit form (hx i,hyi), then hx i and hyi
131
are checked, independently, whether they have a dimension or whether they are dimensionless. If both have
a dimension, the canvas coordinate system is used. If both lack a dimension, the xyz coordinate system is
used. If hx i has a dimension and hyi has not, then the sum of two coordinate (hx i,0pt) and (0,hyi) is used.
If hyi has a dimension and hx i has not, then the sum of two coordinate (hx i,0) and (0pt,hyi) is used.
Note furthermore: An expression like (2+3cm,0) does not mean the same as (2cm+3cm,0). Instead, if
hx i or hyi internally uses a mixture of dimensions and dimensionless values, then all dimensionless values
are “upgraded” to dimensions by interpreting them as pt. So, 2+3cm is the same dimension as 2pt+3cm.
Coordinate system canvas polar
The canvas polar coordinate system allows you to specify polar coordinates. You provide an angle
using the angle= option and a radius using the radius= option. This yields the point on the canvas
that is at the given radius distance from the origin at the given degree. An angle of zero degrees to the
right, a degree of 90 upward.
(no default)
/tikz/cs/angle=hdegreesi
The angle of the coordinate. The angle must always be given in degrees and should be between
−360 and 720.
(no default)
/tikz/cs/radius=hdimensioni
The distance from the origin.
(no default)
/tikz/cs/x radius=hdimensioni
A polar coordinate is, after all, just a point on a circle of the given hradiusi. When you provide an
x-radius and also a y-radius, you specify an ellipse instead of a circle. The radius option has the
same effect as specifying identical x radius and y radius options.
(no default)
/tikz/cs/y radius=hdimensioni
Works like x radius.
\tikz \draw (0,0) -- (canvas polar cs:angle=30,radius=1cm);
The implicit form for canvas polar coordinates is the following: you specify the angle and the distance,
separated by a colon as in (30:1cm).
\tikz \draw
(0cm,0cm) -- (30:1cm) -- (60:1cm) -- (90:1cm)
-- (120:1cm) -- (150:1cm) -- (180:1cm);
Two different radii are specified by writing (30:1cm and 2cm).
For the implicit form, instead of an angle given as a number you can also use certain words. For example,
up is the same as 90, so that you can write \tikz \draw (0,0) --(2ex,0pt) --+(up:1ex); and get
. Apart from up you can use down, left, right, north, south, west, east, north east, north west,
south east, south west, all of which have their natural meaning.
Coordinate system xyz polar
This coordinate system work similarly to the canvas polar system. However, the radius and the angle
are interpreted in the xy-coordinate system, not in the canvas system. More detailed, consider the circle
or ellipse whose half axes are given by the current x-vector and the current y-vector. Then, consider the
point that lies at a given angle on this ellipse, where an angle of zero is the same as the x-vector and
an angle of 90 is the y-vector. Finally, multiply the resulting vector by the given radius factor. Voilà.
(no default)
/tikz/cs/angle=hdegreesi
The angle of the coordinate interpreted in the ellipse whose axes are the x-vector and the y-vector.
/tikz/cs/radius=hfactor i
(no default)
A factor by which the x-vector and y-vector are multiplied prior to forming the ellipse.
(no default)
/tikz/cs/x radius=hdimensioni
A specific factor by which only the x-vector is multiplied.
132
(no default)
/tikz/cs/y radius=hdimensioni
Works like x radius.
\begin{tikzpicture}[x=1.5cm,y=1cm]
\draw[help lines] (0cm,0cm) grid (3cm,2cm);
\draw
\draw
\draw
\draw
(0,0)
(0,0)
(0,0)
(0,0)
-----
(xyz
(xyz
(xyz
(xyz
\draw (xyz polar
-- (xyz polar
-- (xyz polar
-- (xyz polar
\end{tikzpicture}
polar
polar
polar
polar
cs:angle=0,radius=1);
cs:angle=30,radius=1);
cs:angle=60,radius=1);
cs:angle=90,radius=1);
cs:angle=0,radius=2)
cs:angle=30,radius=2)
cs:angle=60,radius=2)
cs:angle=90,radius=2);
The implicit version of this option is the same as the implicit version of canvas polar, only you do not
provide a unit.
\tikz[x={(0cm,1cm)},y={(-1cm,0cm)}]
\draw (0,0) -- (30:1) -- (60:1) -- (90:1)
-- (120:1) -- (150:1) -- (180:1);
Coordinate system xy polar
This is just an alias for xyz polar, which some people might prefer as there is no z-coordinate involved
in the xyz polar coordinates.
13.2.2
Barycentric Systems
In the barycentric coordinate system a point is expressed as the linear combination of multiple vectors. The
idea is that you specify vectors v1 , v2 , . . . , vn and numbers α1 , α2 , . . . , αn . Then the barycentric coordinate
specified by these vectors and numbers is
α1 v1 + α2 v2 + · · · + αn vn
α1 + α2 + · · · + αn
The barycentric cs allows you to specify such coordinates easily.
Coordinate system barycentric
For this coordinate system, the hcoordinate specificationi should be a comma-separated list of expressions
of the form hnode namei=hnumber i. Note that (currently) the list should not contain any spaces before
or after the hnode namei (unlike normal key-value pairs).
The specified coordinate is now computed as follows: Each pair provides one vector and a number. The
vector is the center anchor of the hnode namei. The number is the hnumber i. Note that (currently)
you cannot specify a different anchor, so that in order to use, say, the north anchor of a node you first
have to create a new coordinate at this north anchor. (Using for instance \coordinate(mynorth) at
(mynode.north);.)
133
content oriented
ASCII
DVI
TEX
LATEX
XML
Word PostScript
HTML
PDF
CSS
structure oriented
form oriented
\begin{tikzpicture}
\coordinate (content)
at (90:3cm);
\coordinate (structure) at (210:3cm);
\coordinate (form)
at (-30:3cm);
\node [above]
at (content)
{content oriented};
\node [below left] at (structure) {structure oriented};
\node [below right] at (form)
{form oriented};
\draw [thick,gray] (content.south) -- (structure.north east) -- (form.north west) -- cycle;
\small
\node at (barycentric
\node at (barycentric
\node at (barycentric
\node at (barycentric
\node at (barycentric
\node at (barycentric
\node at (barycentric
\node at (barycentric
\node at (barycentric
\node at (barycentric
\end{tikzpicture}
13.2.3
cs:content=0.5,structure=0.1 ,form=1)
cs:content=1 ,structure=0
,form=0.4)
cs:content=0.5,structure=0.5 ,form=1)
cs:content=0 ,structure=0.25,form=1)
cs:content=0.5,structure=1
,form=0)
cs:content=0.5,structure=1
,form=0.4)
cs:content=1 ,structure=0.2 ,form=0.8)
cs:content=1 ,structure=0.6 ,form=0.8)
cs:content=0.8,structure=0.8 ,form=1)
cs:content=1 ,structure=0.05,form=0.05)
{PostScript};
{DVI};
{PDF};
{CSS};
{XML};
{HTML};
{\TeX};
{\LaTeX};
{Word};
{ASCII};
Node Coordinate System
In pgf and in Tik Z it is quite easy to define a node that you wish to reference at a later point. Once you have
defined a node, there are different ways of referencing points of the node. To do so, you use the following
coordinate system:
Coordinate system node
This coordinate system is used to reference a specific point inside or on the border of a previously
defined node. It can be used in different ways, so let us go over them one by one.
You can use three options to specify which coordinate you mean:
/tikz/cs/name=hnode namei
(no default)
Specifies the node that you wish to use to specify a coordinate. The hnode namei is the name that
was previously used to name the node using the name=hnode namei option or the special node name
syntax.
/tikz/anchor=hanchor i
(no default)
Specifies an anchor of the node. Here is an example:
class Shape
class Rectangle
class Circle
134
class Ellipse
\begin{tikzpicture}
\node (shape)
at
\node (rect)
at
\node (circle) at
\node (ellipse) at
(0,2)
(-2,0)
(2,0)
(6,0)
[draw]
[draw]
[draw]
[draw]
{|class
{|class
{|class
{|class
Shape|};
Rectangle|};
Circle|};
Ellipse|};
\draw (node cs:name=circle,anchor=north) |- (0,1);
\draw (node cs:name=ellipse,anchor=north) |- (0,1);
\draw [arrows = -{Triangle[open, angle=60:3mm]}]
(node cs:name=rect,anchor=north)
|- (0,1) -| (node cs:name=shape,anchor=south);
\end{tikzpicture}
(no default)
/tikz/cs/angle=hdegreesi
It is also possible to provide an angle instead of an anchor. This coordinate refers to a point of
the node’s border where a ray shot from the center in the given angle hits the border. Here is an
example:
\begin{tikzpicture}
\node (start) [draw,shape=ellipse] {start};
\foreach \angle in {-90, -80, ..., 90}
\draw (node cs:name=start,angle=\angle)
.. controls +(\angle:1cm) and +(-1,0) .. (2.5,0);
\end{tikzpicture}
start
It is possible to provide neither the anchor= option nor the angle= option. In this case, Tik Z will
calculate an appropriate border position for you. Here is an example:
se
An ellip
A circle
\begin{tikzpicture}
\path (0,0) node(a) [ellipse,rotate=10,draw] {An ellipse}
(3,-1) node(b) [circle,draw]
{A circle};
\draw[thick] (node cs:name=a) -- (node cs:name=b);
\end{tikzpicture}
Tik Z will be reasonably clever at determining the border points that you “mean,” but, naturally, this
may fail in some situations. If Tik Z fails to determine an appropriate border point, the center will be
used instead.
Automatic computation of anchors works only with the line-to operations --, the vertical/horizontal
versions |- and -|, and with the curve-to operation ... For other path commands, such as parabola or
plot, the center will be used. If this is not desired, you should give a named anchor or an angle anchor.
Note that if you use an automatic coordinate for both the start and the end of a line-to, as in --(node
cs:name=b)--, then two border coordinates are computed with a move-to between them. This is usually
exactly what you want.
If you use relative coordinates together with automatic anchor coordinates, the relative coordinates are
computed relative to the node’s center, not relative to the border point. Here is an example:
Text
\tikz \draw (0,0) node(x) [draw] {Text}
rectangle (1,1)
(node cs:name=x) -- +(1,1);
Similarly, in the following examples both control points are (1, 1):
135
X
Y
\tikz \draw (0,0)
(2,0)
(node
(node
node(x) [draw] {X}
node(y) {Y}
cs:name=x) .. controls +(1,1) and +(-1,1) ..
cs:name=y);
The implicit way of specifying the node coordinate system is to simply use the name of the node in
parentheses as in (a) or to specify a name together with an anchor or an angle separated by a dot as
in (a.north) or (a.10).
Here is a more complete example:
le
ng
ecta
Ar
An
oth
er
rec
tan
gle
se
An ellip
A circle
\begin{tikzpicture}[fill=blue!20]
\draw[help lines] (-1,-2) grid (6,3);
\path (0,0) node(a) [ellipse,rotate=10,draw,fill]
{An ellipse}
(3,-1) node(b) [circle,draw,fill]
{A circle}
(2,2) node(c) [rectangle,rotate=20,draw,fill] {A rectangle}
(5,2) node(d) [rectangle,rotate=-30,draw,fill] {Another rectangle};
\draw[thick] (a.south) -- (b) -- (c) -- (d);
\draw[thick,red,->] (a) |- +(1,3) -| (c) |- (b);
\draw[thick,blue,<->] (b) .. controls +(right:2cm) and +(down:1cm) .. (d);
\end{tikzpicture}
13.2.4
Tangent Coordinate Systems
Coordinate system tangent
This coordinate system, which is available only when the Tik Z library calc is loaded, allows you to
compute the point that lies tangent to a shape. In detail, consider a hnodei and a hpointi. Now, draw a
straight line from the hpointi so that it “touches” the hnodei (more formally, so that it is tangent to this
hnodei). The point where the line touches the shape is the point referred to by the tangent coordinate
system.
The following options may be given:
/tikz/cs/node=hnodei
This key specifies the node on whose border the tangent should lie.
(no default)
/tikz/cs/point=hpointi
(no default)
This key specifies the point through which the tangent should go.
/tikz/cs/solution=hnumber i
Specifies which solution should be used if there are more than one.
(no default)
A special algorithm is needed in order to compute the tangent for a given shape. Currently, tangents
can be computed for nodes whose shape is one of the following:
• coordinate
• circle
136
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
c
\coordinate (a) at (3,2);
\node [circle,draw] (c) at (1,1) [minimum size=40pt] {$c$};
\draw[red] (a) -- (tangent cs:node=c,point={(a)},solution=1) -(c.center) -- (tangent cs:node=c,point={(a)},solution=2) -- cycle;
\end{tikzpicture}
There is no implicit syntax for this coordinate system.
13.2.5
Defining New Coordinate Systems
While the set of coordinate systems that Tik Z can parse via their special syntax is fixed, it is possible and
quite easy to define new explicitly named coordinate systems. For this, the following commands are used:
\tikzdeclarecoordinatesystem{hnamei}{hcodei}
This command declares a new coordinate system named hnamei that can later on be used by writing
(hnamei cs:hargumentsi). When Tik Z encounters a coordinate specified in this way, the hargumentsi
are passed to hcodei as argument #1.
It is now the job of hcodei to make sense of the hargumentsi. At the end of hcodei, the two TEX
dimensions \pgf@x and \pgf@y should be have the x- and y-canvas coordinate of the coordinate.
It is not necessary, but customary, to parse hargumentsi using the key-value syntax. However, you can
also parse it in any way you like.
In the following example, a coordinate system cylindrical is defined.
\makeatletter
\define@key{cylindricalkeys}{angle}{\def\myangle{#1}}
\define@key{cylindricalkeys}{radius}{\def\myradius{#1}}
\define@key{cylindricalkeys}{z}{\def\myz{#1}}
\tikzdeclarecoordinatesystem{cylindrical}%
{%
\setkeys{cylindricalkeys}{#1}%
\pgfpointadd{\pgfpointxyz{0}{0}{\myz}}{\pgfpointpolarxy{\myangle}{\myradius}}
}
\begin{tikzpicture}[z=0.2pt]
\draw [->] (0,0,0) -- (0,0,350);
\foreach \num in {0,10,...,350}
\fill (cylindrical cs:angle=\num,radius=1,z=\num) circle (1pt);
\end{tikzpicture}
\tikzaliascoordinatesystem{hnew namei}{hold namei}
Creates an alias of hold namei.
13.3
Coordinates at Intersections
You will wish to compute the intersection of two paths. For the special and frequent case of two perpendicular lines, a special coordinate system called perpendicular is available. For more general cases, the
intersection library can be used.
13.3.1
Intersections of Perpendicular Lines
A frequent special case of path intersections is the intersection of a vertical line going through a point p and
a horizontal line going through some other point q. For this situation there is a useful coordinate system.
Coordinate system perpendicular
You can specify the two lines using the following keys:
/tikz/cs/horizontal line through={(hcoordinatei)}
Specifies that one line is a horizontal line that goes through the given coordinate.
137
(no default)
(no default)
/tikz/cs/vertical line through={(hcoordinatei)}
Specifies that the other line is vertical and goes through the given coordinate.
However, in almost all cases you should, instead, use the implicit syntax. Here, you write (hpi |- hqi)
or (hqi -| hpi).
For example, (2,1 |- 3,4) and (3,4 -| 2,1) both yield the same as (2,4) (provided the xy-coordinate system has not been modified).
The most useful application of the syntax is to draw a line up to some point on a vertical or horizontal
line. Here is an example:
q2
p2
p1
\begin{tikzpicture}
\path (30:1cm) node(p1) {$p_1$}
(75:1cm) node(p2) {$p_2$};
\draw (-0.2,0) -- (1.2,0) node(xline)[right] {$q_1$};
\draw (2,-0.2) -- (2,1.2) node(yline)[above] {$q_2$};
q1
\draw[->] (p1) -\draw[->] (p2) -\draw[->] (p1) -\draw[->] (p2) -\end{tikzpicture}
(p1
(p2
(p1
(p2
||-|
-|
xline);
xline);
yline);
yline);
Note that in (hci |- hd i) the coordinates hci and hd i are not surrounded by parentheses. If they need
to be complicated expressions (like a computation using the $-syntax), you must surround them with
braces; parentheses will then be added around them.
As an example, let us specify a point that lies horizontally at the middle of the line from A to B and
vertically at the middle of the line from C to D:
A
x
B
X
\begin{tikzpicture}
\node (A) at (0,1) {A};
\node (B) at (1,1.5) {B};
\node (C) at (2,0) {C};
\node (D) at (2.5,-2) {D};
C
\draw (A) -- (B) node [midway] {x};
\draw (C) -- (D) node [midway] {x};
x
\node at ({$(A)!.5!(B)$} -| {$(C)!.5!(D)$}) {X};
\end{tikzpicture}
D
13.3.2
Intersections of Arbitrary Paths
Tik Z Library intersections
\usetikzlibrary{intersections} % LATEX and plain TEX
\usetikzlibrary[intersections] % ConTEXt
This library enables the calculation of intersections of two arbitrary paths. However, due to the low
accuracy of TEX, the paths should not be “too complicated”. In particular, you should not try to intersect
paths consisting of lots of very small segments such as plots or decorated paths.
To find the intersections of two paths in Tik Z, they must be “named”. A “named path” is, quite simply,
a path that has been named using the following key:
(no default)
(no default)
/tikz/name path=hnamei
/tikz/name path global=hnamei
The effect of this key is that, after the path has been constructed, just before it is used, it is associated
with hnamei. For name path, this association survives beyond the final semi-colon of the path but not
the end of the surrounding scope. For name path global, the association will survive beyond any scope
as well. Handle with care.
Any paths created by nodes on the (main) path are ignored, unless this key is explicitly used. If the
same hnamei is used for the main path and the node path(s), then the paths will be added together
and then associated with hnamei.
138
To find the intersection of named paths, the following key is used:
(no default)
/tikz/name intersections={hoptionsi}
This key changes the key path to /tikz/intersection and processes hoptionsi. These options determine, among other things, which paths to use for the intersection. Having processed the options,
any intersections are then found. A coordinate is created at each intersection, which by default, will
be named intersection-1, intersection-2, and so on. Optionally, the prefix intersection can be
changed, and the total number of intersections stored in a TEX-macro.
1
2
\begin{tikzpicture}[every node/.style={opacity=1, black, above left}]
\draw [help lines] grid (3,2);
\draw [name path=ellipse] (2,0.5) ellipse (0.75cm and 1cm);
\draw [name path=rectangle, rotate=10] (0.5,0.5) rectangle +(2,1);
\fill [red, opacity=0.5, name intersections={of=ellipse and rectangle}]
(intersection-1) circle (2pt) node {1}
(intersection-2) circle (2pt) node {2};
\end{tikzpicture}
The following keys can be used in hoptionsi:
/tikz/intersection/of=hname path 1 iandhname path 2 i
This key is used to specify the names of the paths to use for the intersection.
/tikz/intersection/name=hprefix i
(no default)
(no default, initially intersection)
This key specifies the prefix name for the coordinate nodes placed at each intersection.
(no default)
/tikz/intersection/total=hmacroi
This key means that the total number of intersections found will be stored in hmacroi.
4
9
5
\begin{tikzpicture}
\clip (-2,-2) rectangle (2,2);
\draw [name path=curve 1] (-2,-1) .. controls (8,-1) and (-8,1) .. (2,1);
\draw [name path=curve 2] (-1,-2) .. controls (-1,8) and (1,-8) .. (1,2);
3
2
8
1
6
7
\fill [name intersections={of=curve 1 and curve 2, name=i, total=\t}]
[red, opacity=0.5, every node/.style={above left, black, opacity=1}]
\foreach \s in {1,...,\t}{(i-\s) circle (2pt) node {\footnotesize\s}};
\end{tikzpicture}
/tikz/intersection/by=hcomma-separated listi
(no default)
This key allows you to specify a list of names for the intersection coordinates. The intersection
coordinates will still be named hprefix i-hnumber i, but additionally the first coordinate will also
be named by the first element of the hcomma-separated listi. What happens is that the hcommaseparated listi is passed to the \foreach statement and for hlist member i a coordinate is created
at the already-named intersection.
\begin{tikzpicture}
\clip (-2,-2) rectangle (2,2);
\draw [name path=curve 1] (-2,-1) .. controls (8,-1) and (-8,1) .. (2,1);
\draw [name path=curve 2] (-1,-2) .. controls (-1,8) and (1,-8) .. (1,2);
\fill [name intersections={of=curve 1 and curve 2, by={a,b}}]
(a) circle (2pt)
(b) circle (2pt);
\end{tikzpicture}
You can also use the ... notation of the \foreach statement inside the hcomma-separated listi.
139
In case an element of the hcomma-separated listi starts with options in square brackets, these
options are used when the coordinate is created. A coordinate name can still, but need not, follow
the options. This makes it easy to add labels to intersections:
d
c
i
e
b
a
h
g
f
\begin{tikzpicture}
\clip (-2,-2) rectangle (2,2);
\draw [name path=curve 1] (-2,-1) .. controls (8,-1) and (-8,1) .. (2,1);
\draw [name path=curve 2] (-1,-2) .. controls (-1,8) and (1,-8) .. (1,2);
\fill [name intersections={
of=curve 1 and curve 2,
by={[label=center:a],[label=center:...],[label=center:i]}}];
\end{tikzpicture}
/tikz/intersection/sort by=hpath namei
(no default)
By default, the intersections are simply returned in the order that the intersection algorithm finds
them. Unfortunately, this is not necessarily a “helpful” ordering. This key can be used to sort the
intersections along the path specified by hpath namei, which should be one of the paths mentioned
in the /tikz/intersection/of key.
3
1
2
2
1
13.4
13.4.1
3
\begin{tikzpicture}
\clip (-0.5,-0.75) rectangle (3.25,2.25);
\foreach \pathname/\shift in {line/0cm, curve/2cm}{
\tikzset{xshift=\shift}
\draw [->, name path=curve] (1,1.5) .. controls (-1,1) and (2,0.5) .. (0,0);
\draw [->, name path=line] (0,-.5) -- (1,2) ;
\fill [name intersections={of=line and curve,sort by=\pathname, name=i}]
[red, opacity=0.5, every node/.style={left=.25cm, black, opacity=1}]
\foreach \s in {1,2,3}{(i-\s) circle (2pt) node {\footnotesize\s}};
}
\end{tikzpicture}
Relative and Incremental Coordinates
Specifying Relative Coordinates
You can prefix coordinates by ++ to make them “relative.” A coordinate such as ++(1cm,0pt) means “1cm
to the right of the previous position, making this the new current position.” Relative coordinates are often
useful in “local” contexts:
\begin{tikzpicture}
\draw (0,0)
-- ++(1,0) -- ++(0,1) -- ++(-1,0) -- cycle;
\draw (2,0)
-- ++(1,0) -- ++(0,1) -- ++(-1,0) -- cycle;
\draw (1.5,1.5) -- ++(1,0) -- ++(0,1) -- ++(-1,0) -- cycle;
\end{tikzpicture}
Instead of ++ you can also use a single +. This also specifies a relative coordinate, but it does not “update”
the current point for subsequent usages of relative coordinates. Thus, you can use this notation to specify
numerous points, all relative to the same “initial” point:
\begin{tikzpicture}
\draw (0,0)
-- +(1,0) -- +(1,1) -- +(0,1) -- cycle;
\draw (2,0)
-- +(1,0) -- +(1,1) -- +(0,1) -- cycle;
\draw (1.5,1.5) -- +(1,0) -- +(1,1) -- +(0,1) -- cycle;
\end{tikzpicture}
There is a special situation, where relative coordinates are interpreted differently. If you use a relative
coordinate as a control point of a Bézier curve, the following rule applies: First, a relative first control point
140
is taken relative to the beginning of the curve. Second, a relative second control point is taken relative to
the end of the curve. Third, a relative end point of a curve is taken relative to the start of the curve.
This special behavior makes it easy to specify that a curve should “leave or arrive from a certain direction”
at the start or end. In the following example, the curve “leaves” at 30◦ and “arrives” at 60◦ :
\begin{tikzpicture}
\draw (1,0) .. controls +(30:1cm) and +(60:1cm) .. (3,-1);
\draw[gray,->] (1,0) -- +(30:1cm);
\draw[gray,<-] (3,-1) -- +(60:1cm);
\end{tikzpicture}
13.4.2
Rotational Relative Coordinates
You may sometimes wish to specify points relative not only to the previous point, but additionally relative
to the tangent entering the previous point. For this, the following key is useful:
(no value)
/tikz/turn
This key can be given as an option to a hcoordinatei as in the following example:
\tikz \draw (0,0) -- (1,1) -- ([turn]-45:1cm) -- ([turn]-30:1cm);
The effect of this key is to locally shift the coordinate system so that the last point reached is at the
origin and the coordinate system is “turned” so that the x-axis points in the direction of a tangent
entering the last point. This means, in effect, that when you use polar coordinates of the form hrelative
anglei:hdistancei together with the turn option, you specify a point that lies at hdistancei from the last
point in the direction of the last tangent entering the last point, but with a rotation of hrelative anglei.
This key also works with curves . . .
\tikz [delta angle=30, radius=1cm]
\draw (0,0) arc [start angle=0] -- ([turn]0:1cm)
arc [start angle=30] -- ([turn]0:1cm)
arc [start angle=60] -- ([turn]30:1cm);
\tikz \draw (0,0) to [bend left] (2,1) -- ([turn]0:1cm);
. . . and with plots . . .
\tikz \draw plot coordinates {(0,0) (1,1) (2,0) (3,0) } -- ([turn]30:1cm);
Although the above examples use polar coordinates with√turn, you can also use any normal coordinate.
For instance, ([turn]1,1) will append a line of length 2 that is turns by 45◦ relative to the tangent
to the last point.
\tikz \draw (0.5,0.5) -| (2,1) -- ([turn]1,1)
.. controls ([turn]0:1cm) .. ([turn]-90:1cm);
141
13.4.3
Relative Coordinates and Scopes
An interesting question is, how do relative coordinates behave in the presence of scopes? That is, suppose
we use curly braces in a path to make part of it “local,” how does that affect the current position? On the
one hand, the current position certainly changes since the scope only affects options, not the path itself. On
the other hand, it may be useful to “temporarily escape” from the updating of the current point.
Since both interpretations of how the current point and scopes should “interact” are useful, there is a
(local!) option that allows you to decide which you need.
(no default, initially false)
/tikz/current point is local=hbooleani
Normally, the scope path operation has no effect on the current point. That is, curly braces on a path
have no effect on the current position:
\begin{tikzpicture}
\draw
(0,0) -- ++(1,0)
-- ++(0,1)
-- ++(-1,0);
\draw[red] (2,0) -- ++(1,0) { -- ++(0,1) } -- ++(-1,0);
\end{tikzpicture}
If you set this key to true, this behaviour changes. In this case, at the end of a group created on a path,
the last current position reverts to whatever value it had at the beginning of the scope. More precisely,
when Tik Z encounters } on a path, it checks whether at this particular moment the key is set to true.
If so, the current position reverts to the value is had when the matching { was read.
\begin{tikzpicture}
\draw
(0,0) -- ++(1,0)
-- ++(0,1)
-- ++(-1,0);
\draw[red] (2,0) -- ++(1,0)
{ [current point is local] -- ++(0,1) } -- ++(-1,0);
\end{tikzpicture}
In the above example, we could also have given the option outside the scope, for instance as a parameter
to the whole scope.
13.5
Coordinate Calculations
Tik Z Library calc
\usetikzlibrary{calc} % LATEX and plain TEX
\usetikzlibrary[calc] % ConTEXt
You need to load this library in order to use the coordinate calculation functions described in the present
section.
It is possible to do some basic calculations that involve coordinates. In essence, you can add and subtract
coordinates, scale them, compute midpoints, and do projections. For instance, ($(a) + 1/3*(1cm,0)$) is
the coordinate that is 1/3cm to the right of the point a:
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
A
13.5.1
\node (a) at (1,1) {A};
\fill [red] ($(a) + 1/3*(1cm,0)$) circle (2pt);
\end{tikzpicture}
The General Syntax
The general syntax is the following:
([hoptionsi]$hcoordinate computationi$).
As you can see, the syntax uses the TEX math symbol $ to indicate that a “mathematical computation”
is involved. However, the $ has no other effect, in particular, no mathematical text is typeset.
The hcoordinate computationi has the following structure:
1. It starts with
142
hfactor i*hcoordinateihmodifiersi
2. This is optionally followed by + or - and then another
hfactor i*hcoordinateihmodifiersi
3. This is once more followed by + or - and another of the above modified coordinate; and so on.
In the following, the syntax of factors and of the different modifiers is explained in detail.
13.5.2
The Syntax of Factors
The hfactor is are optional and detected by checking whether the hcoordinate computationi starts with a (.
Also, after each ± a hfactor i is present if, and only if, the + or - sign is not directly followed by (.
If a hfactor i is present, it is evaluated using the \pgfmathparse macro. This means that you can use
pretty complicated computations inside a factor. A hfactor i may even contain opening parentheses, which
creates a complication: How does Tik Z know where a hfactor i ends and where a coordinate starts? For
instance, if the beginning of a hcoordinate computationi is 2*(3+4. . . , it is not clear whether 3+4 is part of a
hcoordinatei or part of a hfactor i. Because of this, the following rule is used: Once it has been determined,
that a hfactor i is present, in principle, the hfactor i contains everything up to the next occurrence of *(.
Note that there is no space between the asterisk and the parenthesis.
It is permissible to put the hfactor i in curly braces. This can be used whenever it is unclear where the
hfactor i would end.
Here are some examples of coordinate specifications that consist of exactly one hfactor i and one
hcoordinatei:
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\fill [red] ($2*(1,1)$) circle (2pt);
\fill [green] (${1+1}*(1,.5)$) circle (2pt);
\fill [blue] ($cos(0)*sin(90)*(1,1)$) circle (2pt);
\fill [black] (${3*(4-3)}*(1,0.5)$) circle (2pt);
\end{tikzpicture}
13.5.3
The Syntax of Partway Modifiers
A hcoordinatei can be followed by different hmodifiersi. The first kind of modifier is the partway modifier.
The syntax (which is loosely inspired by Uwe Kern’s xcolor package) is the following:
hcoordinatei!hnumber i!hanglei:hsecond coordinatei
One could write for instance
(1,2)!.75!(3,4)
The meaning of this is: “Use the coordinate that is three quarters on the way from (1,2) to (3,4).”
In general, hcoordinate x i!hnumber i!hcoordinate yi yields the coordinate (1 − hnumber i)hcoordinate x i +
hnumber ihcoordinate yi. Note that this is a bit different from the way the hnumber i is interpreted in the
xcolor package: First, you use a factor between 0 and 1, not a percentage, and, second, as the hnumber i
approaches 1, we approach the second coordinate, not the first. It is permissible to use a hnumber i that is
smaller than 0 or larger than 1. The hnumber i is evaluated using the \pgfmathparse command and, thus,
it can involve complicated computations.
1
0.9
0.5
0.2
0
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\draw (1,0) -- (3,2);
\foreach \i in {0,0.2,0.5,0.9,1}
\node at ($(1,0)!\i!(3,2)$) {\i};
\end{tikzpicture}
The hsecond coordinatei may be prefixed by an hanglei, separated with a colon, as in (1,1)!.5!60:(2,2).
The general meaning of hai!hfactor i!hanglei:hbi is “First, consider the line from hai to hbi. Then rotate
143
this line by hanglei around the point hai. Then the two endpoints of this line will be hai and some point hci.
Use this point hci for the subsequent computation, namely the partway computation.”
Here are two examples:
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,3);
\coordinate (a) at (1,0);
\coordinate (b) at (3,2);
\draw[->] (a) -- (b);
\coordinate (c) at ($ (a)!1! 10:(b) $);
\draw[->,red] (a) -- (c);
\fill ($ (a)!.5! 10:(b) $) circle (2pt);
\end{tikzpicture}
\begin{tikzpicture}
\draw [help lines] (0,0) grid (4,4);
\foreach \i in {0,0.1,...,2}
\fill ($(2,2) !\i! \i*180:(3,2)$) circle (2pt);
\end{tikzpicture}
You can repeatedly apply modifiers. That is, after any modifier you can add another (possibly different)
modifier.
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\draw (0,0) -- (3,2);
\draw[red] ($(0,0)!.3!(3,2)$) -- (3,0);
\fill[red] ($(0,0)!.3!(3,2)!.7!(3,0)$) circle (2pt);
\end{tikzpicture}
13.5.4
The Syntax of Distance Modifiers
A distance modifier has nearly the same syntax as a partway modifier, only you use a hdimensioni (something
like 1cm) instead of a hfactor i (something like 0.5):
hcoordinatei!hdimensioni!hanglei:hsecond coordinatei
When you write hai!hdimensioni!hbi, this means the following: Use the point that is distanced
hdimensioni from hai on the straight line from hai to hbi. Here is an example:
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
15mm
1cm
0cm
\draw (1,0) -- (3,2);
\foreach \i in {0cm,1cm,15mm}
\node at ($(1,0)!\i!(3,2)$) {\i};
\end{tikzpicture}
As before, if you use a hanglei, the hsecond coordinatei is rotated by this much around the hcoordinatei
before it is used.
The combination of an hanglei of 90 degrees with a distance can be used to “offset” a point relative to
a line. Suppose, for instance, that you have computed a point (c) that lies somewhere on a line from (a)
to (b) and you now wish to offset this point by 1cm so that the distance from this offset point to the line is
1cm. This can be achieved as follows:
144
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
1cm
\coordinate (a) at (1,0);
\coordinate (b) at (3,1);
\draw (a) -- (b);
\coordinate (c) at ($ (a)!.25!(b) $);
\coordinate (d) at ($ (c)!1cm!90:(b) $);
\draw [<->] (c) -- (d) node [sloped,midway,above] {1cm};
\end{tikzpicture}
13.5.5
The Syntax of Projection Modifiers
The projection modifier is also similar to the above modifiers: It also gives a point on a line from the
hcoordinatei to the hsecond coordinatei. However, the hnumber i or hdimensioni is replaced by a hprojection
coordinatei:
hcoordinatei!hprojection coordinatei!hanglei:hsecond coordinatei
Here is an example:
(1,2)!(0,5)!(3,4)
The effect is the following: We project the hprojection coordinatei orthogonally onto the line from
hcoordinatei to hsecond coordinatei. This makes it easy to compute projected points:
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\coordinate (a) at (0,1);
\coordinate (b) at (3,2);
\coordinate (c) at (2.5,0);
\draw (a) -- (b) -- (c) -- cycle;
\draw[red]
(a) -- ($(b)!(a)!(c)$);
\draw[orange] (b) -- ($(a)!(b)!(c)$);
\draw[blue]
(c) -- ($(a)!(c)!(b)$);
\end{tikzpicture}
145
14
Syntax for Path Specifications
A path is a series of straight and curved line segments. It is specified following a \path command and the
specification must follow a special syntax, which is described in the subsections of the present section.
\pathhspecificationi;
This command is available only inside a {tikzpicture} environment.
The hspecificationi is a long stream of path operations. Most of these path operations tell Tik Z how the
path is built. For example, when you write --(0,0), you use a line-to operation and it means “continue
the path from wherever you are to the origin.”
At any point where Tik Z expects a path operation, you can also give some graphic options, which is a
list of options in brackets, such as [rounded corners]. These options can have different effects:
1. Some options take “immediate” effect and apply to all subsequent path operations on the path. For
example, the rounded corners option will round all following corners, but not the corners “before”
and if the sharp corners is given later on the path (in a new set of brackets), the rounding effect
will end.
\tikz \draw (0,0) -- (1,1)
[rounded corners] -- (2,0) -- (3,1)
[sharp corners] -- (3,0) -- (2,1);
Another example are the transformation options, which also apply only to subsequent coordinates.
2. The options that have immediate effect can be “scoped” by putting part of a path in curly braces.
For example, the above example could also be written as follows:
\tikz \draw (0,0) -- (1,1)
{[rounded corners] -- (2,0) -- (3,1)}
-- (3,0) -- (2,1);
3. Some options only apply to the path as a whole. For example, the color= option for determining
the color used for, say, drawing the path always applies to all parts of the path. If several different
colors are given for different parts of the path, only the last one (on the outermost scope) “wins”:
\tikz \draw (0,0) -- (1,1)
[color=red] -- (2,0) -- (3,1)
[color=blue] -- (3,0) -- (2,1);
Most options are of this type. In the above example, we would have had to “split up” the path into
several \path commands:
\tikz{\draw (0,0) -- (1,1);
\draw [color=red] (2,0) -- (3,1);
\draw [color=blue] (3,0) -- (2,1);}
By default, the \path command does “nothing” with the path, it just “throws it away.” Thus, if you
write \path(0,0)--(1,1);, nothing is drawn in your picture. The only effect is that the area occupied
by the picture is (possibly) enlarged so that the path fits inside the area. To actually “do” something
with the path, an option like draw or fill must be given somewhere on the path. Commands like
\draw do this implicitly.
Finally, it is also possible to give node specifications on a path. Such specifications can come at different
locations, but they are always allowed when a normal path operation could follow. A node specification
starts with node. Basically, the effect is to typeset the node’s text as normal TEX text and to place it
at the “current location” on the path. The details are explained in Section 17.
Note, however, that the nodes are not part of the path in any way. Rather, after everything has been
done with the path what is specified by the path options (like filling and drawing the path due to a fill
and a draw option somewhere in the hspecificationi), the nodes are added in a post-processing step.
The following style influences scopes:
146
(style, initially empty)
/tikz/every path
This style is installed at the beginning of every path. This can be useful for (temporarily) adding,
say, the draw option to everything in a scope.
\begin{tikzpicture}
[fill=yellow!80!black,
% only sets the color
every path/.style={draw}] % all paths are drawn
\fill (0,0) rectangle +(1,1);
\shade (2,0) rectangle +(1,1);
\end{tikzpicture}
(no default)
/tikz/insert path=hpathi
This key can be used inside an option to add something to the current path. This is mostly useful for
defining styles that create graphic contents. This option should be used with care, for instance it should
not be used as an argument of, say, a node. In the following example, we use a style to add little circles
to a path.
\tikz [c/.style={insert path={circle[radius=2pt]}}]
\draw (0,0) -- (1,1) [c] -- (3,2) [c];
The effect is the same as of (0,0) --(1,1) circle[radius=2pt] -- (3,2) circle[radius=2pt].
The following options are for experts only:
(no default)
/tikz/append after command=hpathi
Some of the path commands described in the following sections take optional arguments. For these
commands, when you use this key inside these options, the hpathi will be inserted after the path
command is done. For instance, when you give this command in the option list of a node, the hpathi
will be added after the node. This is used by, for instance, the label option to allow you to specify a
label in the option list of a node, but have this label cause a node to be added after another node.
\tikz \draw node [append after command={(foo)--(1,1)},draw] (foo){foo};
foo
If this key is called multiple times, the effects accumulate, that is, all of the paths are added in the order
to keys were found.
(no default)
/tikz/prefix after command=hpathi
Works like append after command, only the accumulation order is inverse: The hpathi is added before
any earlier paths added using either append after command or prefix after command.
14.1
The Move-To Operation
The perhaps simplest operation is the move-to operation, which is specified by just giving a coordinate where
a path operation is expected.
\path . . . hcoordinatei . . . ;
The move-to operation normally starts a path at a certain point. This does not cause a line segment to
be created, but it specifies the starting point of the next segment. If a path is already under construction,
that is, if several segments have already been created, a move-to operation will start a new part of the
path that is not connected to any of the previous segments.
\begin{tikzpicture}
\draw (0,0) --(2,0) (0,1) --(2,1);
\end{tikzpicture}
147
In the specification (0,0) --(2,0) (0,1) --(2,1) two move-to operations are specified: (0,0) and
(0,1). The other two operations, namely --(2,0) and --(2,1) are line-to operations, described next.
There is special coordinate called current subpath start that is always at the position of the last
move-to operation on the current path.
\tikz [line width=2mm]
\draw (0,0) -- (1,0) -- (1,1)
-- (0,1) -- (current subpath start);
Note how in the above example the path is not closed (as --cycle would do). Rather, the line just starts
and ends at the origin without being a closed path.
14.2
14.2.1
The Line-To Operation
Straight Lines
\path . . . --hcoordinate or cyclei . . . ;
The line-to operation extends the current path from the current point in a straight line to the given
hcoordinatei (the “or cycle” part is explained in a moment). The “current point” is the endpoint of the
previous drawing operation or the point specified by a prior move-to operation.
When a line-to operation is used and some path segment has just been constructed, for example by
another line-to operation, the two line segments become joined. This means that if they are drawn, the
point where they meet is “joined” smoothly. To appreciate the difference, consider the following two
examples: In the left example, the path consists of two path segments that are not joined, but they
happen to share a point, while in the right example a smooth join is shown.
\begin{tikzpicture}[line width=10pt]
\draw (0,0) --(1,1) (1,1) --(2,0);
\draw (3,0) -- (4,1) -- (5,0);
\useasboundingbox (0,1.5); % make bounding box higher
\end{tikzpicture}
Instead of a coordinate following the two minus signs, you can also use the text cycle. This causes the
straight line from the current point to go to the last point specified by a move-to operation. Note that
this need not be the beginning of the path. Furthermore, a smooth join is created between the first
segment created after the last move-to operation and the straight line appended by the cycle operation.
Consider the following example. In the left example, two triangles are created using three straight lines,
but they are not joined at the ends. In the second example cycle operations are used.
\begin{tikzpicture}[line width=10pt]
\draw (0,0) -- (1,1) -- (1,0) -- (0,0) (2,0) -- (3,1) -- (3,0) -- (2,0);
\draw (5,0) -- (6,1) -- (6,0) -- cycle (7,0) -- (8,1) -- (8,0) -- cycle;
\useasboundingbox (0,1.5); % make bounding box higher
\end{tikzpicture}
Writing cycle instead of a coordinate at the end of a path operation is possible with all path operations
that end with a coordinate (such as -- or .. or sin or grid, but not graph or plot). In all cases, the effect
is that the coordinate of the last moveto is used as the coordinate expected by the path operation and that
a smooth join is added. (What actually happens that the text cycle used with any path operation other
than -- gets replaced by (current subpath start)--cycle.)
148
14.2.2
Horizontal and Vertical Lines
Sometimes you want to connect two points via straight lines that are only horizontal and vertical. For this,
you can use two path construction operations.
\path . . . -|hcoordinate or cyclei . . . ;
This operation means “first horizontal, then vertical.”
B
A
\begin{tikzpicture}
\draw (0,0) node(a) [draw] {A} (1,1) node(b) [draw] {B};
\draw (a.north) |- (b.west);
\draw[color=red] (a.east) -| (2,1.5) -| (b.north);
\end{tikzpicture}
Instead of a coordinate you can also write cycle to close the path:
\begin{tikzpicture}[ultra thick]
\draw (0,0) -- (1,1) -| cycle;
\end{tikzpicture}
\path . . . |-hcoordinate or cyclei . . . ;
This operations means “first vertical, then horizontal.”
14.3
The Curve-To Operation
The curve-to operation allows you to extend a path using a Bézier curve.
\path . . . ..controlshciandhd i..hy or cyclei . . . ;
This operation extends the current path from the current point, let us call it x, via a curve to a point y (if,
instead of a coordinate you say cycle at the end, y will be the coordinate of the last move-to operation).
The curve is a cubic Bézier curve. For such a curve, apart from y, you also specify two control points c
and d. The idea is that the curve starts at x, “heading” in the direction of c. Mathematically spoken,
the tangent of the curve at x goes through c. Similarly, the curve ends at y, “coming from” the other
control point, d. The larger the distance between x and c and between d and y, the larger the curve
will be.
If the “andhd i” part is not given, d is assumed to be equal to c.
\begin{tikzpicture}
\draw[line width=10pt] (0,0) .. controls (1,1) .. (4,0)
.. controls (5,0) and (5,1) .. (4,1);
\draw[color=gray] (0,0) -- (1,1) -- (4,0) -- (5,0) -- (5,1) -- (4,1);
\end{tikzpicture}
\begin{tikzpicture}
\draw[line width=10pt] (0,0) -- (2,0) .. controls (1,1) .. cycle;
\end{tikzpicture}
As with the line-to operation, it makes a difference whether two curves are joined because they resulted
from consecutive curve-to or line-to operations, or whether they just happen to have a common (end)
point:
149
\begin{tikzpicture}[line width=10pt]
\draw (0,0) -- (1,1) (1,1) .. controls (1,0) and (2,0) .. (2,0);
\draw [yshift=-1.5cm]
(0,0) -- (1,1)
.. controls (1,0) and (2,0) .. (2,0);
\end{tikzpicture}
14.4
The Rectangle Operation
A rectangle can obviously be created using four straight lines and a cycle operation. However, since rectangles
are needed so often, a special syntax is available for them.
\path . . . rectanglehcorner or cyclei . . . ;
When this operation is used, one corner will be the current point, another corner is given by hcorner i,
which becomes the new current point.
\begin{tikzpicture}
\draw (0,0) rectangle (1,1);
\draw (.5,1) rectangle (2,0.5) (3,0) rectangle (3.5,1.5) -- (2,0);
\end{tikzpicture}
Just for consistency, you can also use cycle instead of a coordinate, but it is a bit unclear what use
this might have.
14.5
Rounding Corners
All of the path construction operations mentioned up to now are influenced by the following option:
(default 4pt)
/tikz/rounded corners=hinseti
When this option is in force, all corners (places where a line is continued either via line-to or a curve-to
operation) are replaced by little arcs so that the corner becomes smooth.
\tikz \draw [rounded corners] (0,0) -- (1,1)
-- (2,0) .. controls (3,1) .. (4,0);
The hinseti describes how big the corner is. Note that the hinseti is not scaled along if you use a scaling
option like scale=2.
\begin{tikzpicture}
\draw[color=gray,very thin] (10pt,15pt) circle[radius=10pt];
\draw[rounded corners=10pt] (0,0) -- (0pt,25pt) -- (40pt,25pt);
\end{tikzpicture}
You can switch the rounded corners on and off “in the middle of path” and different corners in the same
path can have different corner radii:
\begin{tikzpicture}
\draw (0,0) [rounded corners=10pt] -- (1,1) -- (2,1)
[sharp corners] -- (2,0)
[rounded corners=5pt] -- cycle;
\end{tikzpicture}
Here is a rectangle with rounded corners:
\tikz \draw[rounded corners=1ex] (0,0) rectangle (20pt,2ex);
You should be aware, that there are several pitfalls when using this option. First, the rounded corner
will only be an arc (part of a circle) if the angle is 90◦ . In other cases, the rounded corner will still be
round, but “not as nice.”
150
Second, if there are very short line segments in a path, the “rounding” may cause inadvertent effects.
In such case it may be necessary to temporarily switch off the rounding using sharp corners.
(no value)
/tikz/sharp corners
This options switches off any rounding on subsequent corners of the path.
14.6
The Circle and Ellipse Operations
Circles and ellipses are common path elements for which there is a special path operation.
\path . . . circle[hoptionsi] . . . ;
This command adds a circle to the current path where the center of the circle is the current point
by default, but you can use the at option to change this. The new current point of the path will be
(typically just remain) the center of the circle.
The radius of the circle is specified using the following options:
(no default)
/tikz/x radius=hvaluei
Sets the horizontal radius of the circle (which, when this value is different form the vertical radius,
is actually an ellipse). The hvaluei may either be a dimension or a dimensionless number. In the
latter case, the number is interpreted in the xy-coordinate system (if the x-unit is set to, say, 2cm,
then x radius=3 will have the same effect as x radius=6cm).
(no default)
/tikz/y radius=hvaluei
Works like the x radius.
(no default)
/tikz/radius=hvaluei
Sets the x radius and y radius simultaneously.
(no default)
/tikz/at=hcoordinatei
If this option is explicitly set inside the hoptionsi (or indirectly via the every circle style), the
hcoordinatei is used as the center of the circle instead of the current point. Setting at to some value
in an enclosing scope has no effect.
The hoptionsi may also contain additional options like, say, a rotate or scale, that will only have an
effect on the circle.
\begin{tikzpicture}
\draw (1,0) circle [radius=1.5];
\fill (1,0) circle [x radius=1cm, y radius=5mm, rotate=30];
\end{tikzpicture}
It is possible to set the radius also in some enclosing scope, in this case the options can be left out (but
see the note below on what may follow):
\begin{tikzpicture}[radius=2pt]
\draw (0,0) circle -- (1,1) circle -- ++(0,1) circle;
\end{tikzpicture}
The following style is used with every circle:
(style, no value)
/tikz/every circle
You can use this key to set up, say, a default radius for every circle. The key will also be used with
the ellipse operation.
151
In case you feel that the names radius and x radius are too long for your taste, you can easily created
shorter aliases:
\tikzset{r/.style={radius=#1},rx/.style={x radius=#1},ry/.style={y radius=#1}}
You can then say circle [r=1cm] or circle [rx=1,ry=1.5]. The reason Tik Z uses the longer names
by default is that it encourages people to write more readable code.
Note: There also exists an older syntax for circles, where the radius of the circle is given in parentheses
right after the circle command as in circle (1pt). Although this syntax is a bit more succinct, it
is harder to understand for readers of the code and the use of parentheses for something other than a
coordinate is ill-chosen.
Tik Z will use the following rule to determine whether the old or the normal syntax is used: If circle
is directly followed by something that (expands to) an opening parenthesis, then the old syntax is used
and inside these following parentheses there must be a single number or dimension representing a radius.
In all other cases the new syntax is used.
\path . . . ellipse[hoptionsi] . . . ;
This command has exactly the same effect as circle. The older syntax for this command is ellipse
(hx radiusi and hy radiusi). As for the circle command, this syntax is not as good as the standard
syntax.
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\draw (1,1) ellipse [x radius=1cm,y radius=.5cm];
\end{tikzpicture}
14.7
The Arc Operation
The arc operation allows you to add an arc to the current path.
\path . . . arc[hoptionsi] . . . ;
The arc operation adds a part of an ellipse to the current path. The radii of the ellipse are given by
the values of x radius and y radius, which should be set in the hoptionsi. The arc will start at the
current point and will end at the end of the arc. The arc will start and end at angles computed from the
three keys start angle, end angle, and delta angle. Normally, the first two keys specify the start
and end angle. However, in case one of them is empty, it is computed from the other key plus or minus
the delta angle. In detail, if end angle is empty, it is set to the start angle plus the delta angle. If
the start angle is missing, it is set to the end angle minus the delta angle. If all three keys are set, the
delta angle is ignored.
(no default)
/tikz/start angle=hdegreesi
Sets the start angle.
(no default)
/tikz/end angle=hdegreesi
Sets the end angle.
(no default)
/tikz/delta angle=hdegreesi
Sets the delta angle.
152
\begin{tikzpicture}[radius=1cm]
\draw (0,0) arc[start angle=180, end angle=90]
-- (2,.5) arc[start angle=90, delta angle=-90];
\draw (4,0) -- +(30:1cm)
arc [start angle=30, delta angle=30] -- cycle;
\draw (8,0) arc [start angle=0,
end angle=270,
x radius=1cm, y radius=5mm] -- cycle;
\end{tikzpicture}
α
β
\begin{tikzpicture}[radius=1cm,delta angle=30]
\draw (-1,0) -- +(3.5,0);
\draw (1,0) ++(210:2cm) -- +(30:4cm);
\draw (1,0) +(0:1cm) arc [start angle=0];
\draw (1,0) +(180:1cm) arc [start angle=180];
\path (1,0) ++(15:.75cm) node{$\alpha$};
\path (1,0) ++(15:-.75cm) node{$\beta$};
\end{tikzpicture}
There also exists a shorter syntax for the arc operation, namely arc begin directly followed by (hstart
anglei:hend anglei:hradiusi). However, this syntax is harder to read, so the normal syntax should be
preferred in general.
14.8
The Grid Operation
You can add a grid to the current path using the grid path operation.
\path . . . grid[hoptionsi]hcorner or cyclei . . . ;
This operations adds a grid filling a rectangle whose two corners are given by hcorner i and by the
previous coordinate. (Instead of a coordinate you can also say cycle to use the position of the last
move-to as the corner coordinate, but it not very natural to do so.) corner Thus, the typical way in
which a grid is drawn is \draw (1,1) grid (3,3);, which yields a grid filling the rectangle whose
corners are at (1, 1) and (3, 3). All coordinate transformations apply to the grid.
\tikz[rotate=30] \draw[step=1mm] (0,0) grid (2,2);
The hoptionsi, which are local to the grid operation, can be used to influence the appearance of the
grid. The stepping of the grid is governed by the following options:
/tikz/step=hnumber or dimension or coordinatei
(no default, initially 1cm)
Sets the stepping in both the x and y-direction. If a dimension is provided, this is used directly. If
a number is provided, this number is interpreted in the xy-coordinate system. For example, if you
provide the number 2, then the x-step is twice the x-vector and the y-step is twice the y-vector set
by the x= and y= options. Finally, if you provide a coordinate, then the x-part of this coordinate
will be used as the x-step and the y-part will be used as the y-coordinate.
153
\begin{tikzpicture}[x=.5cm]
\draw[thick] (0,0) grid [step=1]
(3,2);
\draw[red]
(0,0) grid [step=.75cm] (3,2);
\end{tikzpicture}
\begin{tikzpicture}
\draw
(0,0) circle [radius=1];
\draw[blue] (0,0) grid [step=(45:1)] (3,2);
\end{tikzpicture}
A complication arises when the x- and/or y-vector do not point along the axes. Because
of this, the actual rule for computing the x-step and the y-step is the following: As the
x- and y-steps we use the x- and y-components or the following two vectors: The first vector is either (hx-grid-step-number i, 0) or (hx-grid-step-dimensioni, 0pt), the second vector is
(0, hy-grid-step-number i) or (0pt, hx-grid-step-dimensioni).
/tikz/xstep=hdimension or number i
(no default, initially 1cm)
Sets the stepping in the x-direction.
\tikz \draw (0,0) grid [xstep=.5,ystep=.75] (3,2);
/tikz/ystep=hdimension or number i
(no default, initially 1cm)
Sets the stepping in the y-direction.
It is important to note that the grid is always “phased” such that it contains the point (0, 0) if that point
happens to be inside the rectangle. Thus, the grid does not always have an intersection at the corner
points; this occurs only if the corner points are multiples of the stepping. Note that due to rounding
errors, the “last” lines of a grid may be omitted. In this case, you have to add an epsilon to the corner
points.
The following style is useful for drawing grids:
(style, initially line width=0.2pt,gray)
/tikz/help lines
This style makes lines “subdued” by using thin gray lines for them. However, this style is not
installed automatically and you have to say for example:
\tikz \draw[help lines] (0,0) grid (3,3);
14.9
The Parabola Operation
The parabola path operation continues the current path with a parabola. A parabola is a (shifted and
scaled) curve defined by the equation f (x) = x2 and looks like this: .
\path . . . parabola[hoptionsi]bendhbend coordinateihcoordinate or cyclei . . . ;
This operation adds a parabola through the current point and the given hcoordinatei or, if cycle is used
instead of coordinate at the end, the hcoordinatei is set to the position of the last move-to and the path
gets closed after the parabola. If the bend is given, it specifies where the bend should go; the hoptionsi
can also be used to specify where the bend is. By default, the bend is at the old current point.
154
\begin{tikzpicture}
\draw
\draw[xshift=1.5cm]
\draw[xshift=3cm]
\draw[yshift=-2cm]
(0,0)
(0,0)
(0,0)
(0,0)
(0,0)
(0,0)
rectangle
parabola
rectangle
parabola[bend at end]
rectangle
parabola bend (.75,1.75)
(1,1.5) -(0,0) parabola
(1,1.5)
(1,1.5);
(1,1.5)
(1,1.5);
(1,1.5)
(1,1.5);
cycle;
\end{tikzpicture}
The following options influence parabolas:
(no default)
/tikz/bend=hcoordinatei
Has the same effect as saying bendhcoordinatei outside the hoptionsi. The option specifies that
the bend of the parabola should be at the given hcoordinatei. You have to take care yourself
that the bend position is a “valid” position; which means that if there is no parabola of the form
f (x) = ax2 + bx + c that goes through the old current point, the given bend, and the new current
point, the result will not be a parabola.
There is one special property of the hcoordinatei: When a relative coordinate is given like +(0,0),
the position relative to this coordinate is “flexible.” More precisely, this position lies somewhere on
a line from the old current point to the new current point. The exact position depends on the next
option.
(no default)
/tikz/bend pos=hfractioni
Specifies where the “previous” point is relative to which the bend is calculated. The previous point
will be at the hfractionith part of the line from the old current point to the new current point.
The idea is the following: If you say bend pos=0 and bend +(0,0), the bend will be at the old
current point. If you say bend pos=1 and bend +(0,0), the bend will be at the new current point.
If you say bend pos=0.5 and bend +(0,2cm) the bend will be 2cm above the middle of the line
between the start and end point. This is most useful in situations such as the following:
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw (-1,0) parabola[bend pos=0.5] bend +(0,2) +(3,0);
\end{tikzpicture}
In the above example, the bend +(0,2) essentially means “a parabola that is 2cm high” and +(3,0)
means “and 3cm wide.” Since this situation arises often, there is a special shortcut option:
(no default)
/tikz/parabola height=hdimensioni
This option has the same effect as [bend pos=0.5,bend={+(0pt,hdimensioni)}].
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw (-1,0) parabola[parabola height=2cm] +(3,0);
\end{tikzpicture}
The following styles are useful shortcuts:
(style, no value)
/tikz/bend at start
This places the bend at the start of a parabola.
bend pos=0,bend={+(0,0)}.
It is a shortcut for the following options:
(style, no value)
/tikz/bend at end
This places the bend at the end of a parabola.
155
14.10
The Sine and Cosine Operation
The sin and cos operations are similar to the parabola operation. They, too, can be used to draw (parts
of) a sine or cosine curve.
\path . . . sinhcoordinate or cyclei . . . ;
The effect of sin is to draw a scaled and shifted version of a sine curve in the interval [0, π/2]. The
scaling and shifting is done in such a way that the start of the sine curve in the interval is at the old
current point and that the end of the curve in the interval is at hcoordinatei. Here is an example that
should clarify this:
\tikz \draw (0,0) rectangle (1,1)
(0,0) sin (1,1)
(2,0) rectangle +(1.57,1) (2,0) sin +(1.57,1);
\path . . . coshcoordinate or cyclei . . . ;
This operation works similarly, only a cosine in the interval [0, π/2] is drawn. By correctly alternating
sin and cos operations, you can create a complete sine or cosine curve:
\begin{tikzpicture}[xscale=1.57]
\draw (0,0) sin (1,1) cos (2,0) sin (3,-1) cos (4,0) sin (5,1);
\draw[color=red] (0,1.5) cos (1,0) sin (2,-1.5) cos (3,0) sin (4,1.5) cos (5,0);
\end{tikzpicture}
Note that there is no way to (conveniently) draw an interval on a sine or cosine curve whose end points
are not multiples of π/2.
14.11
The SVG Operation
The svg operation can be used to extend the current path by a path given in the svg path data syntax.
This syntax is described in detail in Section 8.3 of the svg 1.1 specification, please consult this specification
for details.
\path . . . svg[hoptionsi]{hpath datai} . . . ;
This operation adds the path specified in the hpath datai in svg 1.1 path data syntax to the current
path. Unlike the svg-specification, it is permissible that the path data does not start with a move-to
command (m or M), in which case the last point of the current path is used as start point. The optional hoptionsi apply locally to this path operation, typically you will use them to set up, say, some
transformations.
upper left
\begin{tikzpicture}
\filldraw [fill=red!20] (0,1) svg[scale=2] {h 10 v 10 h -10}
node [above left] {upper left} -- cycle;
\draw svg {M 0 0 L 20 20 h 10 a 10 10 0 0 0 -20 0};
\end{tikzpicture}
An svg coordinate like 10 20 is always interpreted as (10pt,20pt), so the basic unit is always points
(pt). The xy-coordinate system is not used. However, you can use scaling to (locally) change the basic
unit. For instance, svg[scale=1cm] (yes, this works, although some rather evil magic is involved) will
cause 1cm to be the basic unit.
156
Instead of curly braces, you can also use quotation marks to indicate the start and end of the svg path.
Warning: The arc operations (a and A) are numerically instable. This means that they will be quite
imprecise, except when the angle is a multiple of 90◦ (as is, fortunately, most often the case).
14.12
The Plot Operation
The plot operation can be used to append a line or curve to the path that goes through a large number of
coordinates. These coordinates are either given in a simple list of coordinates, read from some file, or they
are computed on the fly.
Since the syntax and the behaviour of this command are a bit complex, they are described in the separated
Section 22.
14.13
The To Path Operation
The to operation is used to add a user-defined path from the previous coordinate to the following coordinate.
When you write (a) to (b), a straight line is added from a to b, exactly as if you had written (a) --(b).
However, if you write (a) to [out=135,in=45] (b) a curve is added to the path, which leaves at an angle
of 135◦ at a and arrives at an angle of 45◦ at b. This is because the options in and out trigger a special
path to be used instead of the straight line.
\path . . . to[hoptionsi] hnodesi hcoordinate or cyclei . . . ;
This path operation inserts the path currently set via the to path option at the current position. The
hoptionsi can be used to modify (perhaps implicitly) the to path and to set up how the path will be
rendered.
Before the to path is inserted, a number of macros are set up that can “help” the to path. These are
\tikztostart, \tikztotarget, and \tikztonodes; they are explained in the following.
Start and Target Coordinates. The to operation is always followed by a hcoordinatei, called the
target coordinate, or the text cycle, in which case the last move-to is used as a coordinate and the path
gets closed. The macro \tikztotarget is set to this coordinate (without its parentheses). There is also
a start coordinate, which is the coordinate preceding the to operation. This coordinate can be accessed
via the macro \tikztostart. In the following example, for the first to, the macro \tikztostart is
0pt,0pt and the \tikztotarget is 0,2. For the second to, the macro \tikztostart is 10pt,10pt and
\tikztotarget is a. For the third, they are set to a and current subpath start.
a
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\node
(a)
at (2,2) {a};
\draw
(0,0)
to (0,2);
\draw[red] (10pt,10pt) to (a);
\draw[blue] (3,0) -- (3,2) -- (a) to cycle;
\end{tikzpicture}
Nodes on to–paths. It is possible to add nodes to the paths constructed by a to operation. To do
so, you specify the nodes between the to keyword and the coordinate (if there are options to the to
operation, these come first). The effect of (a) to node {x} (b) (typically) is the same as if you had
written (a) --node {x} (b), namely that the node is placed on the to. This can be used to add labels
to tos:
\begin{tikzpicture}
\draw (0,0) to node [sloped,above] {x} (3,2);
x
x
\draw (0,0) to[out=90,in=180] node [sloped,above] {x} (3,2);
\end{tikzpicture}
Instead of writing the node between the to keyword and the target coordinate, you may also use the
following keys to create such nodes:
157
/tikz/edge node=hnode specificationi
(no default)
This key can be used inside the hoptionsi of a to path command. It will add the hnode specificationi
to the list of nodes to be placed on the connecting line, just as if you had written the hnode
specificationi directly after the to keyword:
\begin{tikzpicture}
\draw (0,0) to [edge node={node [sloped,above] {x}}] (3,2);
x
x
\draw (0,0) to [out=90,in=180,
edge node={node [sloped,above] {x}}] (3,2);
\end{tikzpicture}
This key is mostly useful to create labels automatically using other keys.
(no default)
/tikz/edge label=htexti
A shorthand for edge node={node[auto]{htexti}}.
\tikz \draw (0,0) to [edge label=x] (3,2);
x
(no default)
/tikz/edge label’=htexti
A shorthand for edge node={node[auto,swap]{htexti}}.
\tikz \draw (0,0) to [edge label=x, edge label’=y] (3,2);
x
y
When the quotes library is loaded, additional ways of specifying nodes on to–paths become available,
see Section 17.12.2.
Styles for to-paths. In addition to the hoptionsi given after the to operation, the following style is
also set at the beginning of the to path:
(style, initially empty)
/tikz/every to
This style is installed at the beginning of every to.
\tikz[every to/.style={bend left}]
\draw (0,0) to (3,2);
Note that, as explained below, every to path is implicitly surrounded by curly braces. This means
that options like draw given in an every to do not actually influence the path. You can fix this
by using the append after command option:
\tikz[every to/.style={append after command={[draw,dashed]}}]
\draw (0,0) to (3,2);
158
Options. The hoptionsi given with the to allow you to influence the appearance of the to path.
Mostly, these options are used to change the to path. This can be used to change the path from a
straight line to, say, a curve.
The path used is set using the following option:
(no default)
/tikz/to path=hpathi
Whenever an to operation is used, the hpathi is inserted. More precisely, the following path is
added:
{[every to,hoptionsi] hpathi }
The hoptionsi are the options given to the to operation, the hpathi is the path set by this option
to path.
Inside the hpathi, different macros are used to reference the from- and to-coordinates. In detail,
these are:
• \tikztostart will expand to the from-coordinate (without the parentheses).
• \tikztotarget will expand to the to-coordinate.
• \tikztonodes will expand to the nodes between the to operation and the coordinate. Furthermore, these nodes will have the pos option set implicitly.
Let us have a look at a simple example. The standard straight line for a to is achieved by the
following hpathi:
--(\tikztotarget) \tikztonodes
Indeed, this is the default setting for the path. When we write (a) to (b), the hpathi will expand
to (a) --(b), when we write
(a) to[red] node {x} (b)
the hpathi will expand to
(a) --(b) node[red] {x}
It is not possible to specify the path
--\tikztonodes (\tikztotarget)
since Tik Z does not allow one to have a macro after -- that expands to a node.
Now let us have a look at how we can modify the hpathi sensibly. The simplest way is to use a
curve.
\begin{tikzpicture}[to path={
.. controls +(1,0) and +(1,0) .. (\tikztotarget) \tikztonodes}]
c
\node (a) at (0,0) {a};
\node (b) at (2,1) {b};
\node (c) at (1,2) {c};
b
x
a
\draw (a) to node {x} (b)
(a) to
(c);
\end{tikzpicture}
Here is another example:
0
qa
1
qb
\tikzset{
my loop/.style={to path={
.. controls +(80:1) and +(100:1) .. (\tikztotarget) \tikztonodes}},
my state/.style={circle,draw}}
\begin{tikzpicture}[shorten >=2pt]
\node [my state] (a) at (210:1) {$q_a$};
\node [my state] (b) at (330:1) {$q_b$};
\draw[->] (a) to
node[below]
{1} (b)
to [my loop] node[above right] {0} (b);
\end{tikzpicture}
159
(no default)
/tikz/execute at begin to=hcodei
The hcodei is executed prior to the to. This can be used to draw one or more additional paths
or to do additional computations.
(no default)
/tikz/execute at end to=hcodei
Works like the previous option, only this code is executed after the to path has been added.
(style, initially empty)
/tikz/every to
This style is installed at the beginning of every to.
There are a number of predefined to paths, see Section 70 for a reference.
14.14
The Foreach Operation
\path . . . foreachhvariablesi[hoptionsi] in {hpath commandsi} . . . ;
The foreach operation can be used to repeatedly insert the hpath commandsi into the current path.
Naturally, the hpath commandsi should internally reference some of the hvariablesi so that you do not
insert exactly the same path repeatedly, but rather variations. For historical reasons, you can also write
\foreach instead of foreach.
\tikz \draw (0,0) foreach \x in {1,...,3} { -- (\x,1) -- (\x,0) };
See Section 83 for more details on the for-each-command.
14.15
The Let Operation
The let operation is the first of a number of path operations that do not actually extend that path, but have
different, mostly local, effects.
\path . . . lethassignmenti ,hassignmenti,hassignmenti. . . in . . . ;
When this path operation is encountered, the hassignmentis are evaluated, one by one. This will store
coordinate and number in special registers (which are local to Tik Z, they have nothing to do with TEX
registers). Subsequently, one can access the contents of these registers using the macros \p, \x, \y, and
\n.
The first kind of permissible hassignmentis have the following form:
\nhnumber register i={hformulai}
When an assignment has this form, the hformulai is evaluated using the \pgfmathparse operation. The
result is stored in the hnumber register i. If the hformulai involves a dimension anywhere (as in 2*3cm/2),
then the hnumber register i stores the resulting dimension with a trailing pt. A hnumber register i can be
named arbitrarily and is a normal TEX parameter to the \n macro. Possible names are {left corner},
but also just a single digit like 5.
Let us call the path that follows a let operation its body. Inside the body, the \n macro can be used to
access the register.
\n{hnumber register i}
When this macro is used on the left-hand side of an =-sign in a let operation, it has no effect and
is just there for readability. When the macro is used on the right-hand side of an =-sign or in the
body of the let operation, then it expands to the value stored in the hnumber register i. This will
either be a dimensionless number like 2.0 or a dimension like 5.6pt.
For instance, if we say let \n1={1pt+2pt}, \n2={1+2} in ..., then inside the ... part the
macro \n1 will expand to 3pt and \n2 expands to 3.
The second kind of hassignmentsi have the following form:
\phpoint register i={hformulai}
160
Point position registers store a single point, consisting of an x-part and a y-part measured in TEX points
(pt). In particular, point registers do not store nodes or node names. Here is an example:
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\draw let \p{foo} = (1,1), \p2 = (2,0) in
(0,0) -- (\p2) -- (\p{foo});
\end{tikzpicture}
\p{hpoint register i}
When this macro is used on the left-hand side of an =-sign in a let operation, it has no effect and
is just there for readability. When the macro is used on the right-hand side of an =-sign or in the
body of the let operation, then it expands to the x-part (measured in TEX points) of the coordinate
stored in the hregister i, followed, by a comma, followed by the y-part.
For instance, if we say let \p1=(1pt,1pt+2pt) in ..., then inside the ... part the macro \p1
will expand to exactly the seven characters “1pt,3pt”. This means that you when you write (\p1),
this expands to (1pt,3pt), which is presumably exactly what you intended.
\x{hpoint register i}
This macro expands just to the x-part of the point register. If we say as above, as we did above,
let \p1=(1pt,1pt+2pt) in ..., then inside the ... part the macro \x1 expands to 1pt.
\y{hpoint register i}
Works like \x, only for the y-part.
Note that the above macros are available only inside a let operation.
Here is an example where let clauses are used to assemble a coordinate from the x-coordinate of a first
point and the y-coordinate of a second point. Naturally, using the |- notation, this could be written
much more compactly.
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\draw
(1,0) coordinate (first point)
-- (3,2) coordinate (second point);
\fill[red] let \p1 = (first point),
\p2 = (second point) in
(\x1,\y2) circle [radius=2pt];
\end{tikzpicture}
Note that the effect of a let operation is local to the body of the let operation. If you wish to access a
computed coordinate outside the body, you must use a coordinate path operation:
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\path % let’s define some points:
let
\p1
= (1,0),
\p2
= (3,2),
\p{center} = ($ (\p1) !.5! (\p2) $) % center
in
coordinate (p1) at (\p1)
coordinate (p2) at (\p2)
coordinate (center) at (\p{center});
\draw (p1) -- (p2);
\fill[red] (center) circle [radius=2pt];
\end{tikzpicture}
For a more useful application of the let operation, let us draw a circle that touches a given line:
161
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,3);
x
\coordinate (a) at (rnd,rnd);
\coordinate (b) at (3-rnd,3-rnd);
\draw (a) -- (b);
\node (c) at (1,2) {x};
\draw let \p1 = ($ (a)!(c)!(b) - (c) $),
\n1 = {veclen(\x1,\y1)}
in circle [at=(c), radius=\n1];
\end{tikzpicture}
14.16
The Scoping Operation
When Tik Z encounters and opening or a closing brace ({ or }) at some point where a path operation should
come, it will open or close a scope. All options that can be applied “locally” will be scoped inside the scope.
For example, if you apply a transformation like [xshift=1cm] inside the scoped area, the shifting only
applies to the scope. On the other hand, an option like color=red does not have any effect inside a scope
since it can only be applied to the path as a whole.
Concerning the effect of scopes on relative coordinates, please see Section 13.4.3.
14.17
The Node and Edge Operations
The node operation adds a so-called node to a path. This operation is special in the following sense: It does
not change the current path in any way. In other words, this operation is not really a path operation, but
has an effect that is “external” to the path. The edge operation has similar effect in that it adds something
after the main path has been drawn. However, it works like the to operation, that is, it adds a to path to
the picture after the main path has been drawn.
Since these operations are quite complex, they are described in the separate Section 17.
14.18
The Graph Operation
The graph operation can be used to specify easily how a large number of nodes are connected. This operation
is documented in a separate section, see Section 19.
14.19
The Pic Operation
The pic operation is used to insert a “short picture” (hence the “short” name) at the current position of the
path. This operation is somewhat similar to the node operation and discussed in detail in Section 18.
14.20
The PGF-Extra Operation
In some cases you may need to “do some calculations or some other stuff” while a path is constructed. For
this, you would like to suspend the construction of the path and suspend Tik Z’s parsing of the path, you
would then like to have some TEX code executed, and would then like to resume the parsing of the path.
This effect can be achieved using the following path operation \pgfextra. Note that this operation should
only be used by real experts and should only be used deep inside clever macros, not on normal paths.
\pgfextra{hcodei}
This command may only be used inside a Tik Z path. There it is used like a normal path operation.
The construction of the path is temporarily suspended and the hcodei is executed. Then, the path
construction is resumed.
\newdimen\mydim
\begin{tikzpicture}
\mydim=1cm
\draw (0pt,\mydim) \pgfextra{\mydim=2cm} -- (0pt,\mydim);
\end{tikzpicture}
162
\pgfextrahcodei \endpgfextra
This is an alternative syntax for the \pgfextra command. If the code following \pgfextra does not
start with a brace, the hcodei is executed until \endpgfextra is encountered. What actually happens
is that when \pgfextra is not followed by a brace, this completely shuts down the Tik Z parser and
\endpgfextra is a normal macro that restarts the parser.
\newdimen\mydim
\begin{tikzpicture}
\mydim=1cm
\draw (0pt,\mydim)
\pgfextra \mydim=2cm \endpgfextra -- (0pt,\mydim);
\end{tikzpicture}
163
15
Actions on Paths
15.1
Overview
Once a path has been constructed, different things can be done with it. It can be drawn (or stroked) with a
“pen,” it can be filled with a color or shading, it can be used for clipping subsequent drawing, it can be used
to specify the extend of the picture—or any combination of these actions at the same time.
To decide what is to be done with a path, two methods can be used. First, you can use a special-purpose
command like \draw to indicate that the path should be drawn. However, commands like \draw and \fill
are just abbreviations for special cases of the more general method: Here, the \path command is used to
specify the path. Then, options encountered on the path indicate what should be done with the path.
For example, \path (0,0) circle (1cm); means “This is a path consisting of a circle around the origin.
Do not do anything with it (throw it away).” However, if the option draw is encountered anywhere on the
path, the circle will be drawn. “Anywhere” is any point on the path where an option can be given, which is
everywhere where a path command like circle (1cm) or rectangle (1,1) or even just (0,0) would also
be allowed. Thus, the following commands all draw the same circle:
\path [draw] (0,0) circle (1cm);
\path (0,0) [draw] circle (1cm);
\path (0,0) circle (1cm) [draw];
Finally, \draw (0,0) circle (1cm); also draws a path, because \draw is an abbreviation for \path
[draw] and thus the command expands to the first line of the above example.
Similarly, \fill is an abbreviation for \path[fill] and \filldraw is an abbreviation for the command
\path[fill,draw]. Since options accumulate, the following commands all have the same effect:
\path [draw,fill]
(0,0) circle (1cm);
\path [draw] [fill] (0,0) circle (1cm);
\path [fill] (0,0) circle (1cm) [draw];
\draw [fill] (0,0) circle (1cm);
\fill (0,0) [draw] circle (1cm);
\filldraw (0,0) circle (1cm);
In the following subsection the different actions that can be performed on a path are explained. The
following commands are abbreviations for certain sets of actions, but for many useful combinations there are
no abbreviations:
\draw
Inside {tikzpicture} this is an abbreviation for \path[draw].
\fill
Inside {tikzpicture} this is an abbreviation for \path[fill].
\filldraw
Inside {tikzpicture} this is an abbreviation for \path[fill,draw].
\pattern
Inside {tikzpicture} this is an abbreviation for \path[pattern].
\shade
Inside {tikzpicture} this is an abbreviation for \path[shade].
\shadedraw
Inside {tikzpicture} this is an abbreviation for \path[shade,draw].
\clip
Inside {tikzpicture} this is an abbreviation for \path[clip].
\useasboundingbox
Inside {tikzpicture} this is an abbreviation for \path[use as bounding box].
164
15.2
Specifying a Color
The most unspecific option for setting colors is the following:
/tikz/color=hcolor namei
(no default)
This option sets the color that is used for fill, drawing, and text inside the current scope. Any special
settings for filling colors or drawing colors are immediately “overruled” by this option.
The hcolor namei is the name of a previously defined color. For LATEX users, this is just a normal
“LATEX-color” and the xcolor extensions are allowed. Here is an example:
\tikz \fill[color=red!20] (0,0) circle (1ex);
It is possible to “leave out” the color= part and you can also write:
\tikz \fill[red!20] (0,0) circle (1ex);
What happens is that every option that Tik Z does not know, like red!20, gets a “second chance” as a
color name.
For plain TEX users, it is not so easy to specify colors since plain TEX has no “standardized” color naming
mechanism. Because of this, pgf emulates the xcolor package, though the emulation is extremely basic
(more precisely, what I could hack together in two hours or so). The emulation allows you to do the
following:
• Specify a new color using \definecolor. Only the two color models gray and rgb are supported3 .
Example: \definecolor{orange}{rgb}{1,0.5,0}
• Use \colorlet to define a new color based on an old one. Here, the ! mechanism is supported,
though only “once” (use multiple \colorlet for more fancy colors).
Example: \colorlet{lightgray}{black!25}
• Use \color{hcolor namei} to set the color in the current TEX group. \aftergroup-hackery is used
to restore the color after the group.
As pointed out above, the color= option applies to “everything” (except to shadings), which is not always
what you want. Because of this, there are several more specialized color options. For example, the draw=
option sets the color used for drawing, but does not modify the color used for filling. These color options
are documented where the path action they influence is described.
15.3
Drawing a Path
You can draw a path using the following option:
/tikz/draw=hcolor i
(default is scope’s color setting)
Causes the path to be drawn. “Drawing” (also known as “stroking”) can be thought of as picking up a
pen and moving it along the path, thereby leaving “ink” on the canvas.
There are numerous parameters that influence how a line is drawn, like the thickness or the dash pattern.
These options are explained below.
If the optional hcolor i argument is given, drawing is done using the given hcolor i. This color can be
different from the current filling color, which allows you to draw and fill a path with different colors. If
no hcolor i argument is given, the last usage of the color= option is used.
If the special color name none is given, this option causes drawing to be “switched off.” This is useful
if a style has previously switched on drawing and you locally wish to undo this effect.
Although this option is normally used on paths to indicate that the path should be drawn, it also
makes sense to use the option with a {scope} or {tikzpicture} environment. However, this will not
cause all paths to be drawn. Instead, this just sets the hcolor i to be used for drawing paths inside the
environment.
3 ConT Xt users should be aware that \definecolor has a different meaning in ConT Xt. There is a low-level equivalent
E
E
named \pgfutil@definecolor which can be used instead.
165
\begin{tikzpicture}
\path[draw=red] (0,0) -- (1,1) -- (2,1) circle (10pt);
\end{tikzpicture}
The following subsections list the different options that influence how a path is drawn. All of these
options only have an effect if the draw option is given (directly or indirectly).
15.3.1
Graphic Parameters: Line Width, Line Cap, and Line Join
(no default, initially 0.4pt)
/tikz/line width=hdimensioni
Specifies the line width. Note the space.
\tikz \draw[line width=5pt] (0,0) -- (1cm,1.5ex);
There are a number of predefined styles that provide more “natural” ways of setting the line width. You
can also redefine these styles.
(style, no value)
/tikz/ultra thin
Sets the line width to 0.1pt.
\tikz \draw[ultra thin] (0,0) -- (1cm,1.5ex);
(style, no value)
/tikz/very thin
Sets the line width to 0.2pt.
\tikz \draw[very thin] (0,0) -- (1cm,1.5ex);
(style, no value)
/tikz/thin
Sets the line width to 0.4pt.
\tikz \draw[thin] (0,0) -- (1cm,1.5ex);
(style, no value)
/tikz/semithick
Sets the line width to 0.6pt.
\tikz \draw[semithick] (0,0) -- (1cm,1.5ex);
(style, no value)
/tikz/thick
Sets the line width to 0.8pt.
\tikz \draw[thick] (0,0) -- (1cm,1.5ex);
(style, no value)
/tikz/very thick
Sets the line width to 1.2pt.
\tikz \draw[very thick] (0,0) -- (1cm,1.5ex);
(style, no value)
/tikz/ultra thick
Sets the line width to 1.6pt.
\tikz \draw[ultra thick] (0,0) -- (1cm,1.5ex);
166
(no default, initially butt)
/tikz/line cap=htypei
Specifies how lines “end.” Permissible htypei are round, rect, and butt. They have the following effects:
\begin{tikzpicture}
\begin{scope}[line width=10pt]
\draw[line cap=rect] (0,0 ) -- (1,0);
\draw[line cap=butt] (0,.5) -- (1,.5);
\draw[line cap=round] (0,1 ) -- (1,1);
\end{scope}
\draw[white,line width=1pt]
(0,0 ) -- (1,0) (0,.5) -- (1,.5) (0,1 ) -- (1,1);
\end{tikzpicture}
(no default, initially miter)
/tikz/line join=htypei
Specifies how lines “join.” Permissible htypei are round, bevel, and miter. They have the following
effects:
\begin{tikzpicture}[line width=10pt]
\draw[line join=round] (0,0) -- ++(.5,1) -- ++(.5,-1);
\draw[line join=bevel] (1.25,0) -- ++(.5,1) -- ++(.5,-1);
\draw[line join=miter] (2.5,0) -- ++(.5,1) -- ++(.5,-1);
\useasboundingbox (0,1.5); % enlarge bounding box
\end{tikzpicture}
/tikz/miter limit=hfactor i
(no default, initially 10)
When you use the miter join and there is a very sharp corner (a small angle), the miter join may
protrude very far over the actual joining point. In this case, if it were to protrude by more than
hfactor i times the line width, the miter join is replaced by a bevel join.
\begin{tikzpicture}[line width=5pt]
\draw
(0,0) -- ++(5,.5) -- ++(-5,.5);
\draw[miter limit=25] (6,0) -- ++(5,.5) -- ++(-5,.5);
\useasboundingbox (14,0); % make bounding box bigger
\end{tikzpicture}
15.3.2
Graphic Parameters: Dash Pattern
/tikz/dash pattern=hdash patterni
(no default)
Sets the dashing pattern. The syntax is the same as in metafont. For example following pattern on
2pt off 3pt on 4pt off 4pt means “draw 2pt, then leave out 3pt, then draw 4pt once more, then
leave out 4pt again, repeat”.
\begin{tikzpicture}[dash pattern=on 2pt off 3pt on 4pt off 4pt]
\draw (0pt,0pt) -- (3.5cm,0pt);
\end{tikzpicture}
/tikz/dash phase=hdash phasei
(no default, initially 0pt)
Shifts the start of the dash pattern by hphasei.
\begin{tikzpicture}[dash pattern=on 20pt off 10pt]
\draw[dash phase=0pt] (0pt,3pt) -- (3.5cm,3pt);
\draw[dash phase=10pt] (0pt,0pt) -- (3.5cm,0pt);
\end{tikzpicture}
As for the line thickness, some predefined styles allow you to set the dashing conveniently.
167
(style, no value)
/tikz/solid
Shorthand for setting a solid line as “dash pattern.” This is the default.
\tikz \draw[solid] (0pt,0pt) -- (50pt,0pt);
(style, no value)
/tikz/dotted
Shorthand for setting a dotted dash pattern.
\tikz \draw[dotted] (0pt,0pt) -- (50pt,0pt);
(style, no value)
/tikz/densely dotted
Shorthand for setting a densely dotted dash pattern.
\tikz \draw[densely dotted] (0pt,0pt) -- (50pt,0pt);
(style, no value)
/tikz/loosely dotted
Shorthand for setting a loosely dotted dash pattern.
\tikz \draw[loosely dotted] (0pt,0pt) -- (50pt,0pt);
(style, no value)
/tikz/dashed
Shorthand for setting a dashed dash pattern.
\tikz \draw[dashed] (0pt,0pt) -- (50pt,0pt);
(style, no value)
/tikz/densely dashed
Shorthand for setting a densely dashed dash pattern.
\tikz \draw[densely dashed] (0pt,0pt) -- (50pt,0pt);
(style, no value)
/tikz/loosely dashed
Shorthand for setting a loosely dashed dash pattern.
\tikz \draw[loosely dashed] (0pt,0pt) -- (50pt,0pt);
/tikz/dash dot
Shorthand for setting a dashed and dotted dash pattern.
(style, no value)
\tikz \draw[dash dot] (0pt,0pt) -- (50pt,0pt);
(style, no value)
/tikz/densely dash dot
Shorthand for setting a densely dashed and dotted dash pattern.
\tikz \draw[densely dash dot] (0pt,0pt) -- (50pt,0pt);
(style, no value)
/tikz/loosely dash dot
Shorthand for setting a loosely dashed and dotted dash pattern.
\tikz \draw[loosely dash dot] (0pt,0pt) -- (50pt,0pt);
(style, no value)
/tikz/dash dot dot
Shorthand for setting a dashed and dotted dash pattern with more dots.
\tikz \draw[dash dot dot] (0pt,0pt) -- (50pt,0pt);
168
(style, no value)
/tikz/densely dash dot dot
Shorthand for setting a densely dashed and dotted dash pattern with more dots.
\tikz \draw[densely dash dot dot] (0pt,0pt) -- (50pt,0pt);
(style, no value)
/tikz/loosely dash dot dot
Shorthand for setting a loosely dashed and dotted dash pattern with more dots.
\tikz \draw[loosely dash dot dot] (0pt,0pt) -- (50pt,0pt);
15.3.3
Graphic Parameters: Draw Opacity
When a line is drawn, it will normally “obscure” everything behind it as if you had used perfectly opaque
ink. It is also possible to ask Tik Z to use an ink that is a little bit (or a big bit) transparent using the
draw opacity option. This is explained in Section 23 on transparency in more detail.
15.3.4
Graphic Parameters: Double Lines and Bordered Lines
/tikz/double=hcore color i
(default white)
This option causes “two” lines to be drawn instead of a single one. However, this is not what really
happens. In reality, the path is drawn twice. First, with the normal drawing color, secondly with the
hcore color i, which is normally white. Upon the second drawing, the line width is reduced. The net
effect is that it appears as if two lines had been drawn and this works well even with complicated, curved
paths:
\tikz \draw[double]
plot[smooth cycle] coordinates{(0,0) (1,1) (1,0) (0,1)};
You can also use the doubling option to create an effect in which a line seems to have a certain “border”:
\begin{tikzpicture}
\draw (0,0) -- (1,1);
\draw[draw=white,double=red,very thick] (0,1) -- (1,0);
\end{tikzpicture}
(no default, initially 0.6pt)
/tikz/double distance=hdimensioni
Sets the distance the “two” lines are spaced apart. In reality, this is the thickness of the line that is used
to draw the path for the second time. The thickness of the first time the path is drawn is twice the
normal line width plus the given hdimensioni. As a side-effect, this option “selects” the double option.
\begin{tikzpicture}
\draw[very thick,double]
(0,0) arc (180:90:1cm);
\draw[very thick,double distance=2pt] (1,0) arc (180:90:1cm);
\draw[thin,double distance=2pt]
(2,0) arc (180:90:1cm);
\end{tikzpicture}
/tikz/double distance between line centers=hdimensioni
(no default)
This option works like double distance, only the distance is not the distance between (inner) borders
of the two main lines, but between their centers. Thus, the thickness the first time the path is drawn is
the normal line width plus the given hdimensioni, while the line width of the second line that is drawn
is hdimensioni minus the normal line width. As a side-effect, this option “selects” the double option.
\begin{tikzpicture}[double distance between line centers=3pt]
\foreach \lw in {0.5,1,1.5,2,2.5}
\draw[line width=\lw pt,double] (\lw,0) -- ++(4mm,0);
\end{tikzpicture}
\begin{tikzpicture}[double distance=3pt]
\foreach \lw in {0.5,1,1.5,2,2.5}
\draw[line width=\lw pt,double] (\lw,0) -- ++(4mm,0);
\end{tikzpicture}
169
(style, no value)
/tikz/double equal sign distance
This style selects a double line distance such that it corresponds to the distance of the two lines in an
equal sign.
= =⇒
\Huge $=\implies$\tikz[baseline,double equal sign distance]
\draw[double,thick,-implies](0,0.55ex) --++(3ex,0);
= =⇒
= =⇒
15.4
\normalsize $=\implies$\tikz[baseline,double equal sign distance]
\draw[double,-implies](0,0.6ex) --++(3ex,0);
\tiny $=\implies$\tikz[baseline,double equal sign distance]
\draw[double,very thin,-implies](0,0.5ex) -- ++(3ex,0);
Adding Arrow Tips to a Path
In different situations, Tik Z will add arrow tips to the end of a path. For this to happen, a number of
different things need to be specified:
1. You must have used the arrows key, explained in detail in Section 16, to setup which kinds of arrow
tips you would like.
2. The path may not be closed (like a circle or a rectangle) and, if it consists of several subpath, further
restrictions apply as explained in Section 16.
3. The tips key must be set to an appropriate value, see Section 16 once more.
For the current section on paths, it is only important that when you add the tips option to a path that
is not drawn, arrow tips will still be added at the beginning and at the end of the current path. This is true
even when “only” arrow tips get drawn for a path without drawing the path itself. Here is an example:
\tikz \path[tips, -{Latex[open,length=10pt,bend]}] (0,0) to[bend left] (1,0);
\tikz \draw[tips, -{Latex[open,length=10pt,bend]}] (0,0) to[bend left] (1,0);
15.5
Filling a Path
To fill a path, use the following option:
/tikz/fill=hcolor i
(default is scope’s color setting)
This option causes the path to be filled. All unclosed parts of the path are first closed, if necessary.
Then, the area enclosed by the path is filled with the current filling color, which is either the last
color set using the general color= option or the optional color hcolor i. For self-intersection paths and
for paths consisting of several closed areas, the “enclosed area” is somewhat complicated to define and
two different definitions exist, namely the nonzero winding number rule and the even odd rule, see the
explanation of these options, below.
Just as for the draw option, setting hcolor i to none disables filling locally.
\begin{tikzpicture}
\fill (0,0) -- (1,1) -- (2,1);
\fill (4,0) circle (.5cm) (4.5,0) circle (.5cm);
\fill[even odd rule] (6,0) circle (.5cm) (6.5,0) circle (.5cm);
\fill (8,0) -- (9,1) -- (10,0) circle (.5cm);
\end{tikzpicture}
If the fill option is used together with the draw option (either because both are given as options or
because a \filldraw command is used), the path is filled first, then the path is drawn second. This
170
is especially useful if different colors are selected for drawing and for filling. Even if the same color is
used, there is a difference between this command and a plain fill: A “filldrawn” area will be slightly
larger than a filled area because of the thickness of the “pen.”
\begin{tikzpicture}[fill=yellow!80!black,line width=5pt]
\filldraw (0,0) -- (1,1) -- (2,1);
\filldraw (4,0) circle (.5cm) (4.5,0) circle (.5cm);
\filldraw[even odd rule] (6,0) circle (.5cm) (6.5,0) circle (.5cm);
\filldraw (8,0) -- (9,1) -- (10,0) circle (.5cm);
\end{tikzpicture}
15.5.1
Graphic Parameters: Fill Pattern
Instead of filling a path with a single solid color, it is also possible to fill it with a tiling pattern. Imagine a
small tile that contains a simple picture like a star. Then these tiles are (conceptually) repeated infinitely
in all directions, but clipped against the path.
Tiling patterns come in two variants: inherently colored patterns and form-only patterns. An inherently
colored pattern is, say, a red star with a black border and will always look like this. A form-only pattern
may have a different color each time it is used, only the form of the pattern will stay the same. As such,
form-only patterns do not have any colors of their own, but when it is used the current pattern color is used
as its color.
Patterns are not overly flexible. In particular, it is not possible to change the size or orientation of a
pattern without declaring a new pattern. For complicated cases, it may be easier to use two nested \foreach
statements to simulate a pattern, but patterns are rendered much more quickly than simulated ones.
(default is scope’s pattern)
/tikz/pattern=hnamei
This option causes the path to be filled with a pattern. If the hnamei is given, this pattern is used,
otherwise the pattern set in the enclosing scope is used. As for the draw and fill options, setting
hnamei to none disables filling locally.
The pattern works like a fill color. In particular, setting a new fill color will fill the path with a solid
color once more.
Strangely, no hnameis are permissible by default. You need to load for instance the patterns library,
see Section 60, to install predefined patterns.
\begin{tikzpicture}
\draw[pattern=dots] (0,0) circle (1cm);
\draw[pattern=fivepointed stars] (0,0) rectangle (3,1);
\end{tikzpicture}
/tikz/pattern color=hcolor i
(no default)
This option is used to set the color to be used for form-only patterns. This option has no effect on
inherently colored patterns.
\begin{tikzpicture}
\draw[pattern color=red,pattern=fivepointed stars] (0,0) circle (1cm);
\draw[pattern color=blue,pattern=fivepointed stars] (0,0) rectangle (3,1);
\end{tikzpicture}
171
\begin{tikzpicture}
\def\mypath{(0,0) -- +(0,1) arc (180:0:1.5cm) -- +(0,-1)}
\fill
[red]
\mypath;
\pattern[pattern color=white,pattern=bricks] \mypath;
\end{tikzpicture}
15.5.2
Graphic Parameters: Interior Rules
The following two options can be used to decide how interior points should be determined:
(no value)
/tikz/nonzero rule
If this rule is used (which is the default), the following method is used to determine whether a given
point is “inside” the path: From the point, shoot a ray in some direction towards infinity (the direction
is chosen such that no strange borderline cases occur). Then the ray may hit the path. Whenever it
hits the path, we increase or decrease a counter, which is initially zero. If the ray hits the path as the
path goes “from left to right” (relative to the ray), the counter is increased, otherwise it is decreased.
Then, at the end, we check whether the counter is nonzero (hence the name). If so, the point is deemed
to lie “inside,” otherwise it is “outside.” Sounds complicated? It is.
crossings: −1 + 1 = 0
\begin{tikzpicture}
\filldraw[fill=yellow!80!black]
% Clockwise rectangle
(0,0) -- (0,1) -- (1,1) -- (1,0) -- cycle
% Counter-clockwise rectangle
(0.25,0.25) -- (0.75,0.25) -- (0.75,0.75) -- (0.25,0.75) -- cycle;
\draw[->] (0,1) -- (.4,1);
\draw[->] (0.75,0.75) -- (0.3,.75);
crossings: 1 + 1 = 2
\draw[->] (0.5,0.5) -- +(0,1) node[above] {crossings: $-1+1 = 0$};
\begin{scope}[yshift=-3cm]
\filldraw[fill=yellow!80!black]
% Clockwise rectangle
(0,0) -- (0,1) -- (1,1) -- (1,0) -- cycle
% Clockwise rectangle
(0.25,0.25) -- (0.25,0.75) -- (0.75,0.75) -- (0.75,0.25) -- cycle;
\draw[->] (0,1) -- (.4,1);
\draw[->] (0.25,0.75) -- (0.4,.75);
\draw[->] (0.5,0.5) -- +(0,1) node[above] {crossings: $1+1 = 2$};
\end{scope}
\end{tikzpicture}
(no value)
/tikz/even odd rule
This option causes a different method to be used for determining the inside and outside of paths. While
it is less flexible, it turns out to be more intuitive.
With this method, we also shoot rays from the point for which we wish to determine whether it is inside
or outside the filling area. However, this time we only count how often we “hit” the path and declare
the point to be “inside” if the number of hits is odd.
Using the even-odd rule, it is easy to “drill holes” into a path.
crossings: 1 + 1 = 2
\begin{tikzpicture}
\filldraw[fill=yellow!80!black,even odd rule]
(0,0) rectangle (1,1) (0.5,0.5) circle (0.4cm);
\draw[->] (0.5,0.5) -- +(0,1) [above] node{crossings: $1+1 = 2$};
\end{tikzpicture}
172
15.5.3
Graphic Parameters: Fill Opacity
Analogously to the draw opacity, you can also set the fill opacity. Please see Section 23 for more details.
15.6
Generalized Filling: Using Arbitrary Pictures to Fill a Path
Sometimes you wish to “fill” a path with something even more complicated than a pattern, let alone a single
color. For instance, you might wish to use an image to fill the path or some other, complicated drawing. In
principle, this effect can be achieved by first using the path for clipping and then, subsequently, drawing the
desired image or picture. However, there is an option that makes this process much easier:
(no default)
/tikz/path picture=hcodei
When this option is given on a path and when the hcodei is not empty, the following happens: After
all other “filling” operations are done with the path, which are caused by the options fill, pattern
and shade, a local scope is opened and the path is temporarily installed as a clipping path. Then, the
hcodei is executed, which can now draw something. Then, the local scope ends and, possibly, the path
is stroked, provided the draw option has been given.
As with other keys like fill or draw this option needs to be given on a path, setting the path picture
outside a path has no effect (the path picture is cleared at the beginning of each path).
The hcodei can be any normal Tik Z code like \draw ... or \node .... As always, when you include
an external graphic, you need to put it inside a \node.
Note that no special actions are taken to transform the origin in any way. This means that the coordinate
(0,0) is still where is was when the path was being constructed and not – as one might expect – at the
lower left corner of the path. However, you can use the following special node to access the size of the
path:
Predefined node path picture bounding box
This node is of shape rectangle. Its size and position are those of current path bounding box
just before the hcodei of the path picture started to be executed. The hcodei can construct its own
paths, so accessing the current path bounding box inside the hcodei yields the bounding box of
any path that is currently being constructed inside the hcodei.
This is a long text.
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\filldraw [fill=blue!10,draw=blue,thick] (1.5,1) circle (1)
[path picture={
\node at (path picture bounding box.center) {
This is a long text.
};}
];
\end{tikzpicture}
\begin{tikzpicture}[cross/.style={path picture={
\draw[black]
(path picture bounding box.south east) -(path picture bounding box.north west)
(path picture bounding box.south west) -(path picture bounding box.north east);
}}]
\draw [help lines] (0,0) grid (3,2);
\filldraw [cross,fill=blue!10,draw=blue,thick] (1,1) circle (1);
\path
[cross,top color=red,draw=red,thick] (2,0) -- (3,2) -- (3,0);
\end{tikzpicture}
173
\begin{tikzpicture}[path image/.style={
path picture={
\node at (path picture bounding box.center) {
\includegraphics[height=3cm]{#1}
};}}]
\draw
[help lines] (0,0) grid (3,2);
\draw [path image=brave-gnu-world-logo,draw=blue,thick]
(0,1) circle (1);
\draw [path image=brave-gnu-world-logo,draw=red,very thick,->]
(1,0) parabola[parabola height=2cm] (3,0);
\end{tikzpicture}
15.7
Shading a Path
You can shade a path using the shade option. A shading is like a filling, only the shading changes its color
smoothly from one color to another.
(no value)
/tikz/shade
Causes the path to be shaded using the currently selected shading (more on this later). If this option
is used together with the draw option, then the path is first shaded, then drawn.
It is not an error to use this option together with the fill option, but it makes no sense.
\tikz \shade (0,0) circle (1ex);
\tikz \shadedraw (0,0) circle (1ex);
For some shadings it is not really clear how they can “fill” the path. For example, the ball shading
normally looks like this: . How is this supposed to shade a rectangle? Or a triangle?
To solve this problem, the predefined shadings like ball or axis fill a large rectangle completely in a
sensible way. Then, when the shading is used to “shade” a path, what actually happens is that the path is
temporarily used for clipping and then the rectangular shading is drawn, scaled and shifted such that all
parts of the path are filled.
The default shading is a smooth transition from gray to white and from top to bottom. However, other
shadings are also possible, for example a shading that will sweep a color from the center to the corners
outward. To choose the shading, you can use the shading= option, which will also automatically invoke the
shade option. Note that this does not change the shading color, only the way the colors sweep. For changing
the colors, other options are needed, which are explained below.
(no default)
/tikz/shading=hnamei
This selects a shading named hnamei. The following shadings are predefined: axis, radial, and
ball.
\tikz \shadedraw [shading=axis] (0,0) rectangle (1,1);
\tikz \shadedraw [shading=radial] (0,0) rectangle (1,1);
\tikz \shadedraw [shading=ball] (0,0) circle (.5cm);
The shadings as well as additional shadings are described in more detail in Section 65.
To change the color of a shading, special options are needed like left color, which sets the color of
an axis shading from left to right. These options implicitly also select the correct shading type, see the
following example
\tikz \shadedraw [left color=red,right color=blue]
(0,0) rectangle (1,1);
For a complete list of the possible options see Section 65 once more.
174
(no default, initially 0)
/tikz/shading angle=hdegreesi
This option rotates the shading (not the path!) by the given angle. For example, we can turn a
top-to-bottom axis shading into a left-to-right shading by rotating it by 90◦ .
\tikz \shadedraw [shading=axis,shading angle=90] (0,0) rectangle (1,1);
You can also define new shading types yourself. However, for this, you need to use the basic layer directly,
which is, well, more basic and harder to use. Details on how to create a shading appropriate for filling paths
are given in Section 109.3.
15.8
Establishing a Bounding Box
pgf is reasonably good at keeping track of the size of your picture and reserving just the right amount
of space for it in the main document. However, in some cases you may want to say things like “do not
count this for the picture size” or “the picture is actually a little large.” For this you can use the option
use as bounding box or the command \useasboundingbox, which is just a shorthand for \path[use as
bounding box].
/tikz/use as bounding box
(no value)
Normally, when this option is given on a path, the bounding box of the present path is used to determine
the size of the picture and the size of all subsequent paths are ignored. However, if there were previous
path operations that have already established a larger bounding box, it will not be made smaller by
this operation (consider the \pgfresetboundingbox command to reset the previous bounding box).
In a sense, use as bounding box has the same effect as clipping all subsequent drawing against the
current path—without actually doing the clipping, only making pgf treat everything as if it were
clipped.
The first application of this option is to have a {tikzpicture} overlap with the main text:
Left of picture
right of picture.
Left of picture\begin{tikzpicture}
\draw[use as bounding box] (2,0) rectangle (3,1);
\draw (1,0) -- (4,.75);
\end{tikzpicture}right of picture.
In a second application this option can be used to get better control over the white space around the
picture:
Left of picture
right of picture.
Left of picture
\begin{tikzpicture}
\useasboundingbox (0,0) rectangle (3,1);
\fill (.75,.25) circle (.5cm);
\end{tikzpicture}
right of picture.
Note: If this option is used on a path inside a TEX group (scope), the effect “lasts” only until the end
of the scope. Again, this behavior is the same as for clipping.
Consider using \useasboundingbox together with \pgfresetboundingbox in order to replace the
bounding box with a new one.
There is a node that allows you to get the size of the current bounding box. The current bounding box
node has the rectangle shape and its size is always the size of the current bounding box.
Similarly, the current path bounding box node has the rectangle shape and the size of the bounding
box of the current path.
175
\begin{tikzpicture}
\draw[red] (0,0) circle (2pt);
\draw[red] (2,1) circle (3pt);
\draw (current bounding box.south west) rectangle
(current bounding box.north east);
\draw[red] (3,-1) circle (4pt);
\draw[thick] (current bounding box.south west) rectangle
(current bounding box.north east);
\end{tikzpicture}
Occasionally, you may want to align multiple tikzpicture environments horizontally and/or vertically
at some prescribed position. The vertical alignment can be realized by means of the baseline option since
TEX supports the concept of box depth natively. For horizontal alignment, things are slightly more involved.
The following approach is realized by means of negative \hspaces before and/or after the picture, thereby
removing parts of the picture. However, the actual amount of negative horizontal space is provided by means
of image coordinates using the trim left and trim right keys:
/tikz/trim left=hdimension or coordinate or default i
(default 0pt)
The trim left key tells pgf to discard everything which is left of the provided hdimension or
coordinatei. Here, hdimensioni is a single x coordinate of the picture and hcoordinatei is a point
with x and y coordinates (but only its x coordinate will be used). The effect is the same as if you issue
\hspace{-s} where s is the difference of the picture’s bounding box lower left x coordinate and the x
coordinate specified as hdimension or coordinatei:
Text before image.
Text after image.
Text before image.%
\begin{tikzpicture}[trim left]
\draw (-1,-1) grid (3,2);
\fill (0,0) circle (5pt);
\end{tikzpicture}%
Text after image.
Since trim left uses the default trim left=0pt, everything left of x = 0 is removed from the bounding
box.
The following example has once the relative long label −1 and once the shorter label 1. Horizontal
alignment is established with trim left:
176
\begin{tikzpicture}
\draw (0,1) -- (0,0) -- (1,1) -\fill (0,0) circle (2pt);
\node[left] at (0,0) {$-1$};
\end{tikzpicture}
\par
\begin{tikzpicture}
\draw (0,1) -- (0,0) -- (1,1) -\fill (0,0) circle (2pt);
\node[left] at (0,0) {$1$};
\end{tikzpicture}
\par
\begin{tikzpicture}[trim left]
\draw (0,1) -- (0,0) -- (1,1) -\fill (0,0) circle (2pt);
\node[left] at (0,0) {$-1$};
\end{tikzpicture}
\par
\begin{tikzpicture}[trim left]
\draw (0,1) -- (0,0) -- (1,1) -\fill (0,0) circle (2pt);
\node[left] at (0,0) {$1$};
\end{tikzpicture}
−1
1
−1
1
cycle;
cycle;
cycle;
cycle;
Use trim left=default to reset the value.
/tikz/trim right=hdimension or coordinate or default i
(no default)
This key is similar to trim left: it discards everything which is right of the provided hdimension or
coordinatei. As for trim left, hdimensioni denotes a single x coordinate of the picture and hcoordinatei
a coordinate with x and y value (although only its x component will be used).
We use the same example from above and add trim right:
Text before image.
Text after image.
Text before image.%
\begin{tikzpicture}[trim left, trim right=2cm, baseline]
\draw (-1,-1) grid (3,2);
\fill (0,0) circle (5pt);
\end{tikzpicture}%
Text after image.
In addition to trim left=0pt, we also discard everything which is right of x=2cm. Furthermore, the
baseline key supports vertical alignment as well (using the y=0cm baseline).
Use trim right=default to reset the value.
Note that baseline, trim left and trim right are currently the only supported way of truncated
bounding boxes which are compatible with image externalization (see the external library for details).
(no default, initially false)
/pgf/trim lowlevel=true|false
This affects only the basic level image externalization: the initial configuration trim lowlevel=false
stores the normal image, without trimming, and the trimming into a separate file. This allows reduced
bounding boxes without clipping the rest away. The trim lowlevel=true information causes the image
externalization to store the trimmed image, possibly resulting in clipping.
15.9
Clipping and Fading (Soft Clipping)
Clipping path means that all painting on the page is restricted to a certain area. This area need not be
rectangular, rather an arbitrary path can be used to specify this area. The clip option, explained below, is
used to specify the region that is to be used for clipping.
177
A fading (a term that I propose, fadings are commonly known as soft masks, transparency masks,
opacity masks or soft clips) is similar to clipping, but a fading allows parts of the picture to be only “half
clipped.” This means that a fading can specify that newly painted pixels should be partly transparent. The
specification and handling of fadings is a bit complex and it is detailed in Section 23, which is devoted to
transparency in general.
(no value)
/tikz/clip
This option causes all subsequent drawings to be clipped against the current path and the size of
subsequent paths will not be important for the picture size. If you clip against a self-intersecting path,
the even-odd rule or the nonzero winding number rule is used to determine whether a point is inside or
outside the clipping region.
The clipping path is a graphic state parameter, so it will be reset at the end of the current scope.
Multiple clippings accumulate, that is, clipping is always done against the intersection of all clipping
areas that have been specified inside the current scopes. The only way of enlarging the clipping area is
to end a {scope}.
\begin{tikzpicture}
\draw[clip] (0,0) circle (1cm);
\fill[red] (1,0) circle (1cm);
\end{tikzpicture}
It is usually a very good idea to apply the clip option only to the first path command in a scope.
If you “only wish to clip” and do not wish to draw anything, you can use the \clip command, which is
a shorthand for \path[clip].
\begin{tikzpicture}
\clip (0,0) circle (1cm);
\fill[red] (1,0) circle (1cm);
\end{tikzpicture}
To keep clipping local, use {scope} environments as in the following example:
\begin{tikzpicture}
\draw (0,0) -- ( 0:1cm);
\draw (0,0) -- (10:1cm);
\draw (0,0) -- (20:1cm);
\draw (0,0) -- (30:1cm);
\begin{scope}[fill=red]
\fill[clip] (0.2,0.2) rectangle (0.5,0.5);
\draw (0,0) -- (40:1cm);
\draw (0,0) -- (50:1cm);
\draw (0,0) -- (60:1cm);
\end{scope}
\draw (0,0) -- (70:1cm);
\draw (0,0) -- (80:1cm);
\draw (0,0) -- (90:1cm);
\end{tikzpicture}
There is a slightly annoying catch: You cannot specify certain graphic options for the command used
for clipping. For example, in the above code we could not have moved the fill=red to the \fill
command. The reasons for this have to do with the internals of the pdf specification. You do not want
to know the details. It is best simply not to specify any options for these commands.
15.10
Doing Multiple Actions on a Path
If more than one of the basic actions like drawing, clipping and filling are requested, they are automatically
applied in a sensible order: First, a path is filled, then drawn, and then clipped (although it took Apple two
mayor revisions of their operating system to get this right. . . ). Sometimes, however, you need finer control
over what is done with a path. For instance, you might wish to first fill a path with a color, then repaint the
178
path with a pattern and then repaint it with yet another pattern. In such cases you can use the following
two options:
(no default)
/tikz/preaction=hoptionsi
This option can be given to a \path command (or to derived commands like \draw which internally call
\path). Similarly to options like draw, this option only has an effect when given to a \path or as part
of the options of a node; as an option to a {scope} it has no effect.
When this option is used on a \path, the effect is the following: When the path has been completely
constructed and is about to be used, a scope is created. Inside this scope, the path is used but not with
the original path options, but with hoptionsi instead. Then, the path is used in the usual manner. In
other words, the path is used twice: Once with hoptionsi in force and then again with the normal path
options in force.
Here is an example in which the path consists of a rectangle. The main action is to draw this path in
red (which is why we see a red rectangle). However, the preaction is to draw the path in blue, which is
why we see a blue rectangle behind the red rectangle.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
[preaction={draw,line width=4mm,blue}]
[line width=2mm,red] (0,0) rectangle (2,2);
\end{tikzpicture}
Note that when the preactions are preformed, then the path is already “finished.” In particular, applying
a coordinate transformation to the path has no effect. By comparison, applying a canvas transformation
does have an effect. Let us use this to add a “shadow” to a path. For this, we use the preaction to fill
the path in gray, shifted a bit to the right and down:
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
[preaction={fill=black,opacity=.5,
transform canvas={xshift=1mm,yshift=-1mm}}]
[fill=red] (0,0) rectangle (1,2)
(1,2) circle (5mm);
\end{tikzpicture}
Naturally, you would normally create a style shadow that contains the above code. The shadow library,
see Section 66, contains predefined shadows of this kind.
It is possible to use the preaction option multiple times. In this case, for each use of the preaction
option, the path is used again (thus, the hoptionsi do not accumulate in a single usage of the path).
The path is used in the order of preaction options given.
In the following example, we use one preaction to add a shadow and another to provide a shading,
while the main action is to use a pattern.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw [pattern=fivepointed stars]
[preaction={fill=black,opacity=.5,
transform canvas={xshift=1mm,yshift=-1mm}}]
[preaction={top color=blue,bottom color=white}]
(0,0) rectangle (1,2)
(1,2) circle (5mm);
\end{tikzpicture}
A complicated application is shown in the following example, where the path is used several times with
different fadings and shadings to create a special visual effect:
179
Small
Big
\begin{tikzpicture}
[
% Define an interesting style
button/.style={
% First preaction: Fuzzy shadow
preaction={fill=black,path fading=circle with fuzzy edge 20 percent,
opacity=.5,transform canvas={xshift=1mm,yshift=-1mm}},
% Second preaction: Background pattern
preaction={pattern=#1,
path fading=circle with fuzzy edge 15 percent},
% Third preaction: Make background shiny
preaction={top color=white,
bottom color=black!50,
shading angle=45,
path fading=circle with fuzzy edge 15 percent,
opacity=0.2},
% Fourth preaction: Make edge especially shiny
preaction={path fading=fuzzy ring 15 percent,
top color=black!5,
bottom color=black!80,
shading angle=45},
inner sep=2ex
},
button/.default=horizontal lines light blue,
circle
]
\draw [help lines] (0,0) grid (4,3);
\node [button] at (2.2,1) {\Huge Big};
\node [button=crosshatch dots light steel blue,
text=white] at (1,1.5) {Small};
\end{tikzpicture}
(no default)
/tikz/postaction=hoptionsi
The postactions work in the same way as the preactions, only they are applied after the main action
has been taken. Like preactions, multiple postaction options may be given to a \path command, in
which case the path is reused several times, each time with a different set of options in force.
If both pre- and postactions are specified, then the preactions are taken first, then the main action, and
then the post actions.
In the first example, we use a postaction to draw the path, after it has already been drawn:
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
[postaction={draw,line width=2mm,blue}]
[line width=4mm,red,fill=white] (0,0) rectangle (2,2);
\end{tikzpicture}
In another example, we use a postaction to “colorize” a path:
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
[postaction={path fading=south,fill=white}]
[postaction={path fading=south,fading angle=45,fill=blue,opacity=.5}]
[left color=black,right color=red,draw=white,line width=2mm]
(0,0) rectangle (1,2)
(1,2) circle (5mm);
\end{tikzpicture}
15.11
Decorating and Morphing a Path
Before a path is used, it is possible to first “decorate” and/or “morph” it. Morphing means that the path
is replaced by another path that is slightly varied. Such morphings are a special case of the more general
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“decorations” described in detail in Section 24. For instance, in the following example the path is drawn
twice: Once normally and then in a morphed (=decorated) manner.
\begin{tikzpicture}
\draw (0,0) rectangle (3,2);
\draw [red, decorate, decoration=zigzag]
(0,0) rectangle (3,2);
\end{tikzpicture}
Naturally, we could have combined this into a single command using pre- or postaction. It is also possible
to deform shapes:
Hello!
\begin{tikzpicture}
\node [circular drop shadow={shadow scale=1.05},minimum size=3.13cm,
decorate, decoration=zigzag,
fill=blue!20,draw,thick,circle] {Hello!};
\end{tikzpicture}
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16
Arrows
16.1
Overview
Tik Z allows you to add (multiple) arrow tips to the end of lines as in
or in
. It is possible to change
which arrow tips are used “on-the-fly,” you can have several arrow tips in a row, and you can change the
appearance of each of them individually using a special syntax. The following example is a perhaps slightly
“excessive” demonstration of what you can do (you need to load the arrows.meta library for it to work):
A
B
\tikz {
\node [circle,draw] (A)
{A};
\node [circle,draw] (B) [right=of A] {B};
\draw [draw = blue, thick,
arrows={
Computer Modern Rightarrow [sep]
- Latex[blue!50,length=8pt,bend,line width=0pt]
Stealth[length=8pt,open,bend,sep]}]
(A) edge [bend left=45] (B)
(B) edge [in=-110, out=-70,looseness=8] (B);
}
There are a number of predefined generic arrow tip kinds whose appearance you can modify in many
ways using various options. It is also possible to define completely new arrow tip kinds, see Section 100, but
doing this is somewhat harder than configuring an existing kind (it is like the difference between using a
font at different sizes or faces like italics, compared to designing a new font yourself).
In the present section, we go over the various ways in which you can configure which particular arrow
tips are used. The glorious details of how new arrow tips can be defined are explained in Section 100.
At the end of the present section, Section 16.5, you will find a description of the different predefined
arrow tips from the arrows.meta library.
Remark: Almost all of the features described in the following were introduced in version 3.0 of Tik Z.
For compatibility reasons, the old arrow tips are still available. To differentiate between the old and new
arrow tips, the following rule is used: The new, more powerful arrow tips start with an uppercase letter as
in Latex, compared to the old arrow tip latex.
Remark: The libraries arrows and arrows.spaced are deprecated. Use arrows.meta instead/additionally, which allows you to do all that the old libraries offered, plus much more. However, the old libraries
still work and you can even mix old and new arrow tips (only, the old arrow tips cannot be configured in
the ways described in the rest of this section; saying scale=2 for a latex arrow has no effect for instance,
while for Latex arrows it doubles their size as one would expect.)
16.2
Where and When Arrow Tips Are Placed
In order to add arrow tips to the lines you draw, the following conditions must be met:
1. You have specified that arrow tips should be added to lines, using the arrows key or its short form.
2. You set the tips key to some value that causes tips to be drawn (to be explained later).
3. You do not use the clip key (directly or indirectly) with the current path.
4. The path actually has two “end points” (it is not “closed”).
Let us start with an introduction to the basics of the arrows key:
/tikz/arrows=hstart arrow specificationi-hend arrow specificationi
(no default)
This option sets the arrow tip(s) to be used at the start and end of lines. An empty value as in -> for
the start indicates that no arrow tip should be drawn at the start.
Note: Since the arrow option is so often used, you can leave out the text arrows=. What happens is
that every (otherwise unknown) option that contains a - is interpreted as an arrow specification.
\begin{tikzpicture}
\draw[->]
(0,0)
-- (1,0);
\draw[>-Stealth] (0,0.3) -- (1,0.3);
\end{tikzpicture}
182
In the above example, the first start specification is empty and the second is >. The end specifications
are > for the first line and Stealth for the second line. Note that it makes a difference whether > is
used in a start specification or in an end specification: In an end specification it creates, as one would
expect, a pointed tip at the end of the line. In the start specification, however, it creates a “reversed”
version if this arrow – which happens to be what one would expect here.
The above specifications are very simple and only select a single arrow tip without any special configuration options, resulting in the “natural” versions of these arrow tips. It is also possible to “configure”
arrow tips in many different ways, as explained in detail in Section 16.3 below by adding options in
square brackets following the arrow tip kind:
\begin{tikzpicture}
\draw[-{Stealth[red]}] (0,0)
\end{tikzpicture}
-- (1,0);
Note that in the example I had to surround the end specification by braces. This is necessary so that
Tik Z does not mistake the closing square bracket of the Stealth arrow tip’s options for the end of
the options of the \draw command. In general, you often need to add braces when specifying arrow
tips except for simple case like -> or «->, which are pretty frequent, though. When in doubt, say
arrows={hstart speci-hend speci}, that will always work.
It is also possible to specify multiple (different) arrow tips in a row inside a specification, see Section 16.4
below for details.
As was pointed out earlier, to add arrow tips to a path, the path must have “end points” and not be
“closed” – otherwise adding arrow tips makes little sense, after all. However, a path can actually consist of
several subpath, which may be open or not and may even consist of only a single point (a single move-to).
In this case, it is not immediately obvious, where arrow heads should be placed. The actual rules that Tik Z
uses are goverened by the setting of the key tips:
(default true, initially on draw)
/pgf/tips=hvaluei
alias /tikz/tips
This key governs in what situations arrow tips are added to a path. The following hvaluesi are permissible:
• true (the value used when no hvaluei is specified)
• proper
• on draw (the initial value, if the key has not yet been used at all)
• on proper draw
• never or false (same effect)
Firstly, there are a whole bunch of situations where the setting of these (or other) options causes no
arrow tips to be shown:
• If no arrow tips have been specified (for instance, by having said arrows=-), no arrow tips are
drawn.
• If the clip option is set, no arrow tips are drawn.
• If tips has been set to never or false, no arrow tips are drawn.
• If tips has been set to on draw or on proper draw, but the draw option is not set, no arrow tips
are drawn.
• If the path is empty (as in \path ;), no arrow tips are drawn.
• If at least one of the subpaths of a path is closed (cycle is used somewhere or something like
circle or rectangle), arrow tips are never drawn anywhere – even if there are open subpaths.
Now, if we pass all of the above tests, we must have a closer look at the path. All its subpaths must
now be open and there must be at least one subpath. We conside the last one. Arrow tips will only be
added to this last subpath.
1. If this last subpath not degenerate (all coordinates on the subpath are the same as in a single
“move-to” \path (0,0); or in a “move-to” followed by a “line-to” to the same position as in \path
(1,2) --(1,2)), arrow tips are added to this last subpath now.
183
2. If the last subpath is degenerate, we add arrow tips pointing upward at the single coordinate
mentioned in the path, but only for tips begin set to true or to on draw – and not for proper
nor for on proper draw. In other words, “proper” suppresses arrow tips on degenerate paths.
% No path, no arrow tips:
\tikz [<->] \draw;
% Degenerate path, draw arrow tips (but no path, it is degenerate...)
\tikz [<->] \draw (0,0);
% Degenerate path, tips=proper suppresses arrows
\tikz [<->] \draw [tips=proper] (0,0);
% Normal case:
\tikz [<->] \draw (0,0) -- (1,0);
% Two subpaths, only second gets tips
\tikz [<->] \draw (0,0) -- (1,0) (2,0) -- (3,0);
% Two subpaths, second degenerate, but still gets tips
\tikz [<->] \draw (0,0) -- (1,0) (2,0);
% Two subpaths, second degenerate, proper suppresses them
\tikz [<->] \draw [tips=on proper draw] (0,0) -- (1,0) (2,0);
% Two subpaths, but one is closed: No tips, even though last subpath is open
\tikz [<->] \draw (0,0) circle[radius=2pt] (2,0) -- (3,0);
One common pitfall when arrow tips are added to a path should be addressed right here at the beginning:
When Tik Z positions an arrow tip at the start, for all its computations it only takes into account the first
segment of the subpath to which the arrow tip is added. This “first segment” is the first line-to or curve-to
operation (or arc or parabola or a similar operation) of the path; but note that decorations like snake will
add many small line segments to paths. The important point is that if this first segment is very small,
namely smaller that the arrow tip itself, strange things may result. As will be explained in Section 16.3.8,
Tik Z will modify the path by shortening the first segment and shortening a segment below its length may
result in strange effects. Similarly, for tips at the end of a subpath, only the last segment is considered.
The bottom line is that wherever an arrow tip is added to a path, the line segment where it is added
should be “long enough.”
16.3
Arrow Keys: Configuring the Appearance of a Single Arrow Tip
For standard arrow tip kinds, like Stealth or Latex or Bar, you can easily change their size, aspect ratio,
color, and other parameters. This is similar to selecting a font face from a font family: “This text” is not
just typeset in the font “Computer Modern,” but rather in “Computer Modern, italic face, 11pt size, medium
weight, black color, no underline, . . . ” Similarly, an arrow tip is not just a “Stealth” arrow tip, but rather a
“Stealth arrow tip at its natural size, flexing, but not bending along the path, miter line caps, draw and fill
colors identical to the path draw color, . . . ”
Just as most programs make it easy to “configure” which font should be used at a certain point in a text,
Tik Z tries to make it easy to specify which configuration of an arrow tip should be used. You use arrow keys,
where a certain parameter like the length of an arrow is set to a given value using the standard key–value
syntax. You can provide several arrow keys following an arrow tip kind in an arrow tip specification as in
Stealth[length=4pt,width=2pt].
While selecting a font may be easy, designing a new font is a highly creative and difficult process and
more often than not, not all faces of a font are available on any given system. The difficulties involved in
designing a new arrow tip are somewhat similar to designing a new letter for a font and, thus, it may also
happen that not all configuration options are actually implemented for a given arrow tip. Naturally, for the
184
standard arrow tips, all configuration options are available – but for special-purpose arrow tips it may well
happen that an arrow tip kind simply “ignores” some of the configurations given by you.
Some of the keys explained in the following are defined in the library arrows.meta, others are always
available. This has to do with the question of whether the arrow key needs to be supported directly in the
pgf core or not. In general, the following explanations assume that arrows.meta has been loaded.
16.3.1
Size
The most important configuration parameter of an arrow tip is undoubtedly its size. The following two keys
are the main keys that are important in this context:
/pgf/arrow keys/length=hdimensionihline width factor ihouter factor i
(no default)
This parameter is usually the most important parameter that governs the size of an arrow tip: The
hdimensioni that you provide dictates the distance from the “very tip” of the arrow to its “back end”
along the line:
5mm
\tikz{
\draw [-{Stealth[length=5mm]}] (0,0) -- (2,0);
\draw [|<->|] (1.5,.4) -- node[above=1mm] {5mm} (2,.4);
}
5mm
\tikz{
\draw [-{Latex[length=5mm]}] (0,0) -- (2,0);
\draw [|<->|] (1.5,.4) -- node[above=1mm] {5mm} (2,.4);
}
5mm
\tikz{
\draw [-{Classical TikZ Rightarrow[length=5mm]}] (0,0) -- (2,0);
\draw [|<->|] (1.5,.6) -- node[above=1mm] {5mm} (2,.6);
}
The Line Width Factors. Following the hdimensioni, you may put a space followed by a hline width
factor i, which must be a plain number (no pt or cm following). When you provide such a number, the
size of the arrow tip is not just hdimensioni, but rather hdimensioni + hline width factor i · w where w
is the width of the to-be-drawn path. This makes it easy to vary the size of an arrow tip in accordance
with the line width – usually a very good idea since thicker lines will need thicker arrow tips.
As an example, when you write length=0pt 5, the length of the arrow will be exactly five times the
current line width. As another example, the default length of a Latex arrow is length=3pt 4.5 0.8.
Let us ignore the 0.8 for a moment; the 4pt 4.5 then means that for the standard line width of 0.4pt,
the length of a Latex arrow will be exactly 4.8pt (3pt plus 4.5 times 0.4pt).
Following the line width factor, you can additionally provide an houter factor i, again preceded by a
space (the 0.8 in the above example). This factor is taken into consideration only when the double
option is used, that is, when a so-called “inner line width”. For a double line, we can identify three
different “line widths”, namely the inner line width wi , the line width wo of the two outer lines, and the
“total line width” wt = wi + 2wo . In the below examples, we have wi = 3pt, wo = 1pt, and wt = 5pt.
It is not immediately clear which of these line widths should be considered as w in the above formula
hdimensioni + hline width factor i · w for the computation of the length. One can argue both for wt and
also for wo . Because of this, you use the houter factor i to decide on one of them or even mix them:
Tik Z sets w = houter factor iwo + (1 − houter factor i)wt . Thus, when the outer factor is 0, as in the
first of the following examples and as is the default when it is not specified, the computed w will be the
total line width wt = 5pt. Since w = 5pt, we get a total length of 15pt in the first example (because of
the factor 3). In contrast, in the last example, the outer factor is 1 and, thus, w = wo = 1pt and the
resulting length is 3pt. Finally, for the middle case, the “middle” between 5pt and 1pt is 3pt, so the
length is 9pt.
\tikz \draw [line width=1pt, double distance=3pt,
arrows = {-Latex[length=0pt 3 0]}] (0,0) -- (1,0);
185
\tikz \draw [line width=1pt, double distance=3pt,
arrows = {-Latex[length=0pt 3 .5]}] (0,0) -- (1,0);
\tikz \draw [line width=1pt, double distance=3pt,
arrows = {-Latex[length=0pt 3 1]} ] (0,0) -- (1,0);
The Exact Length. For an arrow tip kind that is just an outline that is filled with a color, the specified
length should exactly equal the distance from the tip to the back end. However, when the arrow tip is
drawn by stroking a line, it is no longer obvious whether the length should refer to the extend of the
stroked lines’ path or of the resulting pixels (which will be wider because of the thickness of the stroking
pen). The rules are as follows:
1. If the arrow tip consists of a closed path (like Stealth or Latex), imagine the arrow tip drawn
from left to right using a miter line cap. Then the length should be the horizontal distance from
the first drawn “pixel” to the last drawn “pixel”. Thus, the thickness of the stroked line and also
the miter ends should be taken into account:
10mm
\tikz{
\draw [line width=1mm, -{Stealth[length=10mm, open]}]
(0,0) -- (2,0);
\draw [|<->|] (2,.6) -- node[above=1mm] {10mm} ++(-10mm,0);
}
2. If, in the above case, the arrow is drawn using a round line join (see Section 16.3.7 for details on
how to select this), the size of the arrow should still be the same as in the first case (that is, as if a
miter join were used). This creates some “visual consistency” if the two modes are mixed or if you
later one change the mode.
10mm
\tikz{
\draw [line width=1mm, -{Stealth[length=10mm, open, round]}]
(0,0) -- (2,0);
\draw [|<->|] (2,.6) -- node[above=1mm] {10mm} ++(-10mm,0);
}
As the above example shows, however, a rounded arrow will still exactly “tip” the point where the
line should end (the point (2,0) in the above case). It is only the scaling of the arrow that is not
affected.
/pgf/arrow keys/width=hdimensionihline width factor ihouter factor i
(no default)
This key works line the length key, only it specifies the “width” of the arrow tip; so if width and
length are identical, the arrow will just touch the borders of a square. (An exception to this rule are
“halved” arrow tips, see Section 16.3.5.) The meaning of the two optional factor numbers following the
hdimensioni is the same as for the length key.
\tikz \draw [arrows = {-Latex[width=10pt, length=10pt]}] (0,0) -- (1,0);
\tikz \draw [arrows = {-Latex[width=0pt 10, length=10pt]}] (0,0) -- (1,0);
/pgf/arrow keys/width’=hdimensionihlength factor ihline width factor i
(no default)
The key (note the prime) has a similar effect as the width key. The difference is that the second, still
optional paraemter hlength factor i specifies the width of the key not as a multiple of the line width, but
as a multiple of the arrow length.
The idea is that if you write, say, width’=0pt 0.5, the width of the arrow will be half its length. Indeed,
for standard arrow tips like Stealth the default width is specified in this way so that if you change the
length of an arrow tip, you also change the width in such a way that the aspect ratio of the arrow tip is
kept. The other way round, if you modify the factor in width’ without changing the length, you change
the aspect ratio of the arrow tip.
Note that later changes of the length are taken into account for the computation. For instance, if you
write
186
length = 10pt, width’=5pt 2, length=7pt
the resulting width will be 19pt = 5pt + 2 · 7pt.
\tikz \draw [arrows = {-Latex[width’=0pt .5, length=10pt]}] (0,0) -- (1,0);
\tikz \draw [arrows = {-Latex[width’=0pt .5, length=15pt]}] (0,0) -- (1,0);
The third, also optional, parameter allows you to add a multiple of the line width to the value computed
in terms of the length.
/pgf/arrow keys/inset=hdimensionihline width factor ihouter factor i
(no default)
The key is relevant only for some arrow tips such as the Stealth arrow tip. It specifies a distance by
which something inside the arrow tip is set inwards; for the Stealth arrow tip it is the distance by
which the back angle is moved inwards.
The computation of the distance works in the same way as for length and width: To the hdimensioni
we add hline width factor i times that line width, where the line width is computed based on the houter
factor i as described for the length key.
\tikz \draw [arrows = {-Stealth[length=10pt, inset=5pt]}] (0,0) -- (1,0);
\tikz \draw [arrows = {-Stealth[length=10pt, inset=2pt]}] (0,0) -- (1,0);
For most arrows for which there is no “natural inset” like, say, Latex, this key has no effect.
/pgf/arrow keys/inset’=hdimensionihlength factor ihline width factor i
(no default)
This key works like inset, only like width’ the second parameter is a factor of the arrow length rather
than of the line width. For instance, the Stealth arrow sets inset’ to 0pt 0.325 to ensure that the
inset is always at 13/40th of the arrow length if nothing else is specified.
/pgf/arrow keys/angle=hanglei:hdimensionihline width factor ihouter factor i
(no default)
This key sets the length and the width of an arrow tip at the same time. The lenght will be the cosine
of hanglei, while the width will be twice the sine of half the hanglei (this slightly awkward rule ensures
that a Stealth arrow will have an opening angle of hanglei at its tip if this option is used). As for
the length key, if the optional factors are given, they add a certain multiple of the line width to the
hdimensioni before the sine and cosines are computed.
\tikz \draw [arrows = {-Stealth[inset=0pt, angle=90:10pt]}] (0,0) -- (1,0);
\tikz \draw [arrows = {-Stealth[inset=0pt, angle=30:10pt]}] (0,0) -- (1,0);
(no default)
/pgf/arrow keys/angle’=hanglei
Sets the width of the arrow to twice the tangent of hanglei/2 times the arrow length. This results in an
arrow tip with an opening angle of hanglei at its tip and with the specified length unchanged.
\tikz \draw [arrows = {-Stealth[inset=0pt, length=10pt, angle’=90]}]
(0,0) -- (1,0);
\tikz \draw [arrows = {-Stealth[inset=0pt, length=10pt, angle’=30]}]
(0,0) -- (1,0);
187
16.3.2
Scaling
In the previous section we saw that there are many options for getting “fine control” overt the length and
width of arrow tips. However, in some cases, you do not really care whether the arrow tip is 4pt long or
4.2pt long, you “just want it to be a little bit larger than usual.” In such cases, the following keys are useful:
/pgf/arrows keys/scale=hfactor i
(no default, initially 1)
After all the other options listed in the previous (and also the following sections) have been processed,
Tik Z applies a scaling to the computed length, inset, and width of the arrow tip (and, possibly, to other
size parameters defined by special-purpose arrow tip kinds). Everything is simply scaled by the given
hfactor i.
\tikz {
\draw [arrows = {-Stealth[]}]
(0,1)
-- (1,1);
\draw [arrows = {-Stealth[scale=1.5]}] (0,0.5) -- (1,0.5);
\draw [arrows = {-Stealth[scale=2]}]
(0,0)
-- (1,0);
}
Note that scaling has no effect on the line width (as usual) and also not on the arrow padding (the sep).
You can get even more fine-grained control over scaling using the following keys (the scale key is just a
shorthand for setting both of the following keys simultaneously):
/pgf/arrows keys/scale length=hfactor i
(no default, initially 1)
This factor works like scale, only it is applied only to dimensions “along the axis of the arrow,” that
is, to the length and to the inset, but not to the width.
\tikz {
\draw [arrows = {-Stealth[]}]
(0,1)
-- (1,1);
\draw [arrows = {-Stealth[scale length=1.5]}] (0,0.5) -- (1,0.5);
\draw [arrows = {-Stealth[scale length=2]}]
(0,0)
-- (1,0);
}
/pgf/arrows keys/scale width=hfactor i
(no default, initially 1)
Like scale length, but for dimensions related to the width.
\tikz {
\draw [arrows = {-Stealth[]}]
(0,1)
-- (1,1);
\draw [arrows = {-Stealth[scale width=1.5]}] (0,0.5) -- (1,0.5);
\draw [arrows = {-Stealth[scale width=2]}]
(0,0)
-- (1,0);
}
16.3.3
Arc Angles
A few arrow tips consist mainly of arcs, whose length can be specified. For these arrow tips, you use the
following key:
(no default, initially 180)
/pgf/arrow keys/arc=hdegreesi
Sets the angle of arcs in arrows to hdegreesi. Note that this key is quite different from the angle key,
which is “just a fancy way of setting the length and width.” In contrast, the arc key is used to set the
degrees of arcs that are part of an arrow tip:
\tikz [ultra thick] {
\draw [arrows = {-Hooks[]}]
\draw [arrows = {-Hooks[arc=90]}]
\draw [arrows = {-Hooks[arc=270]}]
}
16.3.4
Slanting
You can “slant” arrow tips using the following key:
188
(0,1)
-- (1,1);
(0,0.5) -- (1,0.5);
(0,0)
-- (1,0);
/pgf/arrow keys/slant=hfactor i
(no default, initially 0)
Slanting is used to create an “italics” effect for arrow tips: All arrow tips get “slanted” a little bit relative
to the axis of the arrow:
\tikz {
\draw [arrows = {->[]}]
(0,1)
-- (1,1);
\draw [arrows = {->[slant=.5]}] (0,0.5) -- (1,0.5);
\draw [arrows = {->[slant=1]}] (0,0)
-- (1,0);
}
There is one thing to note about slanting: Slanting is done using a so-called “canvas transformation”
and has no effect on positioning of the arrow tip. In particular, if an arrow tip gets slanted so strongly
that it starts to protrude over the arrow tip end, this does not change the positioning of the arrow tip.
Here is another example where slanting is used to match italic text:
A
16.3.5
B
C
\tikz [>={[slant=.3] To[] To[]}]
\graph [math nodes] { A -> B <-> C };
Reversing, Halving, Swapping
(no value)
/pgf/arrow keys/reverse
Adding this key to an arrow tip will “reverse its direction” so that is points in the opposite direction
(but is still at that end of the line where the non-reversed arrow tip would have been drawn; so only
the tip is reversed). For most arrow tips, this just results in an internal flip of a coordinate system, but
some arrow tips actually use a slightly different version of the tip for reversed arrow tips (namely when
the joining of the tip with the line would look strange). All of this happens automatically, so you do
not need to worry about this.
If you apply this key twice, the effect cancels, which is useful for the definition of shorthands (which
will be discussed later).
\tikz [ultra thick] \draw [arrows = {-Stealth[reversed]}] (0,0) -- (1,0);
\tikz [ultra thick] \draw [arrows = {-Stealth[reversed, reversed]}] (0,0) -- (1,0);
(no value)
/pgf/arrow keys/harpoon
The key requests that only the “left half” of the arrow tip should drawn:
\tikz [ultra thick] \draw [arrows = {-Stealth[harpoon]}] (0,0) -- (1,0);
\tikz [ultra thick] \draw [arrows = {->[harpoon]}] (0,0) -- (1,0);
Unlike the reverse key, which all arrows tip kinds support at least in a basic way, designers of arrow
tips really need to take this key into account in their arrow tip code and often a lot of special attention
needs to do be paid to this key in the implementation. For this reason, only some arrow tips will support
it.
(no value)
/pgf/arrow keys/swap
This key flips that arrow tip along the axis of the line. It makes sense only for asymmetric arrow tips
like the harpoons created using the harpoon option.
\tikz [ultra thick] \draw [arrows = {-Stealth[harpoon]}] (0,0) -- (1,0);
\tikz [ultra thick] \draw [arrows = {-Stealth[harpoon,swap]}] (0,0) -- (1,0);
Swapping is always possible, no special code is needed on behalf of an arrow tip implementer.
(no value)
/pgf/arrow keys/left
A shorthand for harpoon.
189
(no value)
/pgf/arrow keys/right
A shorthand for harpoon, swap.
\tikz [ultra thick] \draw [arrows = {-Stealth[left]}] (0,0) -- (1,0);
\tikz [ultra thick] \draw [arrows = {-Stealth[right]}] (0,0) -- (1,0);
16.3.6
Coloring
Arrow tips are drawn using the same basic mechanisms as normal paths, so arrow tips can be stroked (drawn)
and/or filled. However, we usually want the color of arrow tips to be identical to the color used to draw the
path, even if a different color is used for filling the path. On the other hand, we may also sometimes wish
to use a special color for the arrow tips that is different from both the line and fill colors of the main path.
The following options allow you to configure how arrow tips are colored:
/pgf/arrow keys/color=hcolor or emptyi
(no default, initially empty)
Normally, an arrow tip gets the same color as the path to which it is attached. More precisely, it will
get the current “draw color”, also known as “stroke color,” which you can set using draw=hsome color i.
By adding the option color= to an arrow tip (note that an “empty” color is specified in this way), you
ask that the arrow tip gets this default draw color of the path. Since this is the default behaviour, you
usually do not need to specify anything:
\tikz [ultra thick] \draw [red, arrows = {-Stealth}] (0,0) -- (1,0);
\tikz [ultra thick] \draw [blue, arrows = {-Stealth}] (0,0) -- (1,0);
Now, when you provide a hcolor i with this option, you request that the arrow tip should get this color
instead of the color of the main path:
\tikz [ultra thick] \draw [red, arrows = {-Stealth[color=blue]}] (0,0) -- (1,0);
\tikz [ultra thick] \draw [red, arrows = {-Stealth[color=black]}] (0,0) -- (1,0);
Similar to the color option used in normal Tik Z options, you may omit the color= part of the option.
Whenever an harrow keyi is encountered that Tik Z does not recognize, it will test whether the key is
the name of a color and, if so, execute color=harrow keyi. So, the first of the above examples can be
rewritten as follows:
\tikz [ultra thick] \draw [red, arrows = {-Stealth[blue]}] (0,0) -- (1,0);
The hcolor i will apply both to any drawing and filling operations used to construct the path. For
instance, even though the Stealth arrow tips looks like a filled quadrilateral, it is actually constructed
by drawing a quadrilateral and then filling it in the same color as the drawing (see the fill option
below to see the difference).
When color is set to an empty text, the drawing color is always used to fill the arrow tips, even if a
different color is specified for filling the path:
\tikz [ultra thick] \draw [draw=red, fill=red!50, arrows = {-Stealth[length=10pt]}]
(0,0) -- (1,1) -- (2,0);
As you can see in the above example, the filled area is not quite what you might have expected. The
reason is that the path was actually internally shortened a bit so that the end of the “fat line” as inside
the arrow tip and we get a “clear” arrow tip.
In general, it is a good idea not to add arrow tips to paths that are filled.
190
/pgf/arrow keys/fill=hcolor or none i
(no default)
Use this key to explicitly set the color used for filling the arrow tips. This color can be different from
the color used to draw (stroke) the arrow tip:
\tikz {
\draw [help lines] (0,-.5) grid [step=1mm] (1,.5);
\draw [thick, red, arrows = {-Stealth[fill=white,length=15pt]}] (0,0) -- (1,0);
}
You can also specify the special “color” none. In this case, the arrow tip is not filled at all (not even
with white):
\tikz {
\draw [help lines] (0,-.5) grid [step=1mm] (1,.5);
\draw [thick, red, arrows = {-Stealth[fill=none,length=15pt]}] (0,0) -- (1,0);
}
Note that such “open” arrow tips are a bit difficult to draw in some case: The problem is that the line
must be shortened by just the right amount so that it ends exactly on the back end of the arrow tip.
In some cases, especially when double lines are used, this will not be possible.
(no value)
/pgf/arrow keys/open
A shorthand for fill=none.
When you use both the color and fill option, the color option must come first since it will reset the
filling to the color specified for drawing.
\tikz {
\draw [help lines] (0,-.5) grid [step=1mm] (1,.5);
\draw [thick, red, arrows = {-Stealth[color=blue, fill=white, length=15pt]}]
(0,0) -- (1,0);
}
Note that by setting fill to the special color pgffillcolor, you can cause the arrow tips to be filled
using the color used to fill the main path. (This special color is always available and always set to the
current filling color of the graphic state.):
\tikz [ultra thick] \draw [draw=red, fill=red!50,
arrows = {-Stealth[length=15pt, fill=pgffillcolor]}]
(0,0) -- (1,1) -- (2,0);
16.3.7
Line Styling
Arrow tips are created by drawing and possibly filling a path that makes up the arrow tip. When Tik Z draws
a path, there are different ways in which such a path can be drawn (such as dashing). Three particularly
important parameters are the line join, the line cap, see Section 15.3.1 for an introduction, and the line
width (thickness)
Tik Z resets the line cap and line join each time it draws an arrow tip since you usually do not want their
settings to “spill over” to the way the arrow tips are drawn. You can, however, change there values explicitly
for an arrow tip:
/pgf/arrow keys/line cap=hround or butt i
(no default)
Sets the line cap of all lines that are drawn in the arrow to a round cap or a butt cap. (Unlike for
normal lines, the rect cap is not allowed.) Naturally, this key has no effect for arrows whose paths are
closed.
Each arrow tip has a default value for the line cap, which can be overruled using this option.
Changing the cap should have no effect on the size of the arrow. However, it will have an effect on
where the exact “tip” of the arrow is since this will always be exactly at the end of the arrow:
\tikz [line width=2mm]
\draw [arrows = {-Computer Modern Rightarrow[line cap=butt]}]
(0,0) -- (1,0);
191
\tikz [line width=2mm]
\draw [arrows = {-Computer Modern Rightarrow[line cap=round]}]
(0,0) -- (1,0);
\tikz [line width=2mm]
\draw [arrows = {-Bracket[reversed,line cap=butt]}]
(0,0) -- (1,0);
\tikz [line width=2mm]
\draw [arrows = {-Bracket[reversed,line cap=round]}]
(0,0) -- (1,0);
/pgf/arrow keys/line join=hround or miter i
(no default)
Sets the line join to round or miter (bevel is not allowed). This time, the key only has an effect on
paths that have “corners” in them. The same rules as for line cap apply: the size is not affects, but
the tip end is:
\tikz [line width=2mm]
\draw [arrows = {-Computer Modern Rightarrow[line join=miter]}]
(0,0) -- (1,0);
\tikz [line width=2mm]
\draw [arrows = {-Computer Modern Rightarrow[line join=round]}]
(0,0) -- (1,0);
\tikz [line width=2mm]
\draw [arrows = {-Bracket[reversed,line join=miter]}]
(0,0) -- (1,0);
\tikz [line width=2mm]
\draw [arrows = {-Bracket[reversed,line join=round]}]
(0,0) -- (1,0);
The following keys set both of the above:
(no value)
/pgf/arrow keys/round
A shorthand for line cap=round, line join=round, resulting in “rounded” arrow heads.
\tikz [line width=2mm]
\draw [arrows = {-Computer Modern Rightarrow[round]}] (0,0) -- (1,0);
\tikz [line width=2mm]
\draw [arrows = {-Bracket[reversed,round]}] (0,0) -- (1,0);
(no value)
/pgf/arrow keys/sharp
A shorthand for line cap=butt, line join=miter, resulting in “sharp” or “pointed” arrow heads.
\tikz [line width=2mm]
\draw [arrows = {-Computer Modern Rightarrow[sharp]}] (0,0) -- (1,0);
\tikz [line width=2mm]
\draw [arrows = {-Bracket[reversed,sharp]}] (0,0) -- (1,0);
192
You can also set the width of lines used inside arrow tips:
/pgf/arrow keys/line width=hdimensionihline width factor ihouter factor i
(no default)
This key sets the line width inside an arrow tip for drawing (out)lines of the arrow tip. When you set
this width to 0pt, which makes sense only for closed tips, the arrow tip is only filled. This can result
in better rendering of some small arrow tips and in case of bend arrow tips (because the line joins will
also be bend and not “mitered”.)
The meaning of the factors is as usual the same as for length or width.
\tikz \draw [arrows = {-Latex[line width=0.1pt, fill=white, length=10pt]}] (0,0) -- (1,0);
\tikz \draw [arrows = {-Latex[line width=1pt, fill=white, length=10pt]}] (0,0) -- (1,0);
/pgf/arrow keys/line width’=hdimensionihlength factor i
(no default)
Works like line width only the factor is with respect to the length.
16.3.8
Bending and Flexing
Up to now, we have only added arrow tip to the end of straight lines, which is in some sense “easy.” Things
get far more difficult, if the line to which we wish to end an arrow tip is curved. In the following, we have a
look at the different actions that can be taken and how they can be configured.
To get a feeling for the difficulties involved, consider the following situation: We have a “gray wall” at
the x-coordinate of and a red line that ends in its middle.
\def\wall{ \fill
[fill=black!50] (1,-.5) rectangle (2,.5);
\pattern [pattern=bricks] (1,-.5) rectangle (2,.5);
\draw
[line width=1pt] (1cm+.5pt,-.5) -- ++(0,1); }
\begin{tikzpicture}
\wall
% The "line"
\draw [red,line width=1mm] (-1,0) -- (1,0);
\end{tikzpicture}
Now we wish to add a blue open arrow tip the red line like, say, Stealth[length=1cm,open,blue]:
\begin{tikzpicture}
\wall
\draw [red,line width=1mm,-{Stealth[length=1cm,open,blue]}]
(-1,0) -- (1,0);
\end{tikzpicture}
There are several noteworthy things about the blue arrow tip:
1. Notice that the red line no longer goes all the way to the wall. Indeed, the red line ends more or less
exactly where it meets the blue line, leaving the arrow tip empty. Now, recall that the red line was
supposed to be the path (-2,0)--(1,0); however, this path has obviously become much shorter (by
6.25mm to be precise). This effect is called path shortening in Tik Z.
2. The very tip of the arrow just “touches” the wall, even we zoom out a lot. This point, where the
original path ended and where the arrow tip should now lie, is called the tip end in Tik Z.
3. Finally, the point where the red line touches the blue line is the point where the original path “visually
ends.” Notice that this is not the same as the point that lies at a distance of the arrow’s length from
the wall – rather it lies at a distance of length minus the inset. Let us call this point the visual end
of the arrow.
As pointed out earlier, for straight lines, shortening the path and rotating and shifting the arrow tip so
that it ends precisely at the tip end and the visual end lies on a line from the tip end to the start of the line
is relatively easy.
For curved lines, things are much more difficult and Tik Z copes with the difficulties in different ways,
depending on which options you add to arrows. Here is now a curved red line to which we wish to add our
arrow tip (the original straight red line is shown in light red):
193
\begin{tikzpicture}
\wall
\draw [red!25,line width=1mm] (-1,0) -- (1,0);
\draw [red,line width=1mm] (-1,-.5) .. controls (0,-.5) and (0,0) .. (1,0);
\end{tikzpicture}
The first way of dealing with curved lines is dubbed the “quick and dirty” way (although the option for
selecting this option is politely just called “quick” . . . ):
/pgf/arrow keys/quick
(no value)
Recall that curves in Tik Z are actually Bézier curves, which means that they start and end at certain
points and we specify two vectors, one for the start and one for the end, that provide tangents to the
curve at these points. In particular, for the end of the curve, there is a point called the second support
point of the curve such that a tangent to the curve at the end goes through this point. In our above
example, the second support point is at the middle of the light red line and, indeed, a tangent to the
red line at the point touching the wall is perfectly horizontal.
In order to add our arrow tip to the curved path, our first objective is to “shorten” the path by 6.25mm.
Unfortunately, this is now much more difficult than for a straight path. When the quick option is added
to an arrow tip (it is also the default if no special libraries are loaded), we cheat somewhat: Instead
of really moving along 6.25mm along the path, we simply shift the end of the curve by 6.25mm along
the tangent (which is easy to compute). We also have to shift the second support point by the same
amount to ensure that the line still has the same tangent at the end. This will result in the following:
\begin{tikzpicture}
\wall
\draw [red!25,line width=1mm] (-1,0) -- (1,0);
\draw [red,line width=1mm,-{Stealth[length=1cm,open,blue,quick]}]
(-1,-.5) .. controls (0,-.5) and (0,0) .. (1,0);
\end{tikzpicture}
They main problem with the above picture is that the red line is no longer equal to the original red
line (notice much sharper curvature near its end). In our example this is not such a bad thing, but it
certainly “not a nice thing” that adding arrow tips to a curve changes the overall shape of the curves.
This is especially bothersome if there are several similar curves that have different arrow heads. In this
case, the similar curves now suddenly look different.
Another big problem with the above approach is that it works only well if there is only a single arrow
tip. When there are multiple ones, simply shifting them along the tangent as the quick option does
produces less-than-satisfactory results:
\begin{tikzpicture}
\wall
\draw [red!25,line width=1mm] (-1,0) -- (1,0);
\draw [red,line width=1mm,-{[quick,sep]»>}]
(-1,-.5) .. controls (0,-.5) and (0,0) .. (1,0);
\end{tikzpicture}
Note that the third arrow tip does not really lie on the curve any more.
Because of the shortcomings of the quick key, more powerful mechanisms for shortening lines and rotating
arrows tips have been implemented. To use them, you need to load the following library:
Tik Z Library bending
\usetikzlibrary{bending} % LATEX and plain TEX
\usetikzlibrary[bending] % ConTEXt
Load this library to use the flex, flex’, or bending arrow keys. When this library is loaded, flex
becomes the default mode that is used with all paths, unless quick is explicitly selected for the arrow
tip.
/pgf/arrow keys/flex=hfactor i
(default 1)
When the bending library is loaded, this key is applied to all arrow tips by default. It has the following
effect:
194
1. Instead of simply shifting the visual end of the arrow along the tangent of the curve’s end, we
really move it along the curve by the necessary distance. This operation is more expensive than
the quick operation – but not that expensive, only expensive enough so that it is not selected
by default for all arrow tips. Indeed, some compromises are made in the implementation where
accuracy was traded for speed, so the distance by which the line end is shifted is not necessarily
exactly 6.25mm; only something reasonably close.
2. The supports of the line are updated accordingly so that the shortened line will still follow exactly
the original line. This means that the curve deformation effect caused by the quick command does
not happen here.
3. Next, the arrow tip is rotated and shifted as follows: First, we shift it so that its tip is exactly at
the tip end, where the original line ended. Then, the arrow is rotated so the the visual end lies on
the line:
\begin{tikzpicture}
\wall
\draw [red!25,line width=1mm] (-1,0) -- (1,0);
\draw [red,line width=1mm,-{Stealth[length=1cm,open,blue,flex]}]
(-1,-.5) .. controls (0,-.5) and (0,0) .. (1,0);
\end{tikzpicture}
As can be seen in the example, the flex option gives a result that is visually pleasing and does not
deform the path.
There is, however, one possible problem with the flex option: The arrow tip no longer points along the
tangent of the end of the path. This may or may not be a problem, put especially for larger arrow tips
readers will use the orientation of the arrow head to gauge the direction of the tangent of the line. If
this tangent is important (for example, if it should be horizontal), then it may be necessary to enforce
that the arrow tip “really points in the direction of the tangent.
To achieve this, the flex option takes an optional hfactor i parameter, which defaults to 1. This factor
specifies how much the arrow tip should be rotated: If set to 0, the arrow points exactly along a tangent
to curve at its tip. If set to 1, the arrow point exactly along a line from the visual end point on the
curve to the tip. For values in the middle, we interpolate the rotation between these two extremes; so
flex=.5 will rotate the arrow’s visual end “halfway away from the tangent towards the actual position
on the line.”
\begin{tikzpicture}
\wall
\draw [red!25,line width=1mm] (-1,0) -- (1,0);
\draw [red,line width=1mm,-{Stealth[length=1cm,open,blue,flex=0]}]
(-1,-.5) .. controls (0,-.5) and (0,0) .. (1,0);
\end{tikzpicture}
\begin{tikzpicture}
\wall
\draw [red!25,line width=1mm] (-1,0) -- (1,0);
\draw [red,line width=1mm,-{Stealth[length=1cm,open,blue,flex=.5]}]
(-1,-.5) .. controls (0,-.5) and (0,0) .. (1,0);
\end{tikzpicture}
Note how in the above examples the red line is visible inside the open arrow tip. Open arrow tips do
not go well with a flex value other than 1. Here is a more realistic use of the flex=0 key:
\begin{tikzpicture}
\wall
\draw [red!25,line width=1mm] (-1,0) -- (1,0);
\draw [red,line width=1mm,-{Stealth[length=1cm,flex=0]}]
(-1,-.5) .. controls (0,-.5) and (0,0) .. (1,0);
\end{tikzpicture}
If there are several arrow tips on a path, the flex option positions them independently, so that each of
them lies optimally on the path:
195
\begin{tikzpicture}
\wall
\draw [red!25,line width=1mm] (-1,0) -- (1,0);
\draw [red,line width=1mm,-{[flex,sep]»>}]
(-1,-.5) .. controls (0,-.5) and (0,0) .. (1,0);
\end{tikzpicture}
/pgf/arrow keys/flex’=hfactor i
(default 1)
The flex’ key is almost identical to the flex key. The only difference is that a factor of 1 corresponds
to rotating the arrow tip so that the instead of the visual end, the “ultimate back end” of the arrow tip
lies on the red path. In the example instead of having the arrow tip at a distance of 6.25mm from the
tip lie on the path, we have the point at a distance of 1cm from the tip lie on the path:
\begin{tikzpicture}
\wall
\draw [red!25,line width=1mm] (-1,0) -- (1,0);
\draw [red,line width=1mm,-{Stealth[length=1cm,open,blue,flex’]}]
(-1,-.5) .. controls (0,-.5) and (0,0) .. (1,0);
\end{tikzpicture}
Otherwise, the factor works as for flex and, indeed flex=0 and flex’=0 have the same effect.
The main use of this option is not so much with an arrow tip like Stealth but rather with tips like the
standard > in the context of a strongly curved line:
\begin{tikzpicture}
\wall
\draw [red!25,line width=1mm] (-1,0) -- (1,0);
\draw [red,line width=1mm,-{Computer Modern Rightarrow[flex]}]
(0,-.5) .. controls (1,-.5) and (0.5,0) .. (1,0);
\end{tikzpicture}
In the example, the flex option does not really flex the arrow since for a tip like the Computer Modern
arrow, the visual end is the same as the arrow tip – after all, the red line does, indeed, end almost
exactly where it used to end.
Nevertheless, you may feel that the arrow tip looks “wrong” in the sense that it should be rotated. This
is exactly what the flex’ option does since it allows us to align the “back end” of the tip with the red
line:
\begin{tikzpicture}
\wall
\draw [red!25,line width=1mm] (-1,0) -- (1,0);
\draw [red,line width=1mm,-{Computer Modern Rightarrow[flex’=.75]}]
(0,-.5) .. controls (1,-.5) and (0.5,0) .. (1,0);
\end{tikzpicture}
In the example, I used flex’=.75 so as not to overpronounce the effect. Usually, you will have to fiddle
with it sometime to get the “perfectly aligned arrow tip,” but a value of .75 is usually a good start.
(no value)
/pgf/arrow keys/bend
Bending an arrow tip is a radical solution to the problem of positioning arrow tips on a curved line:
The arrow tip is no longer “rigid” but the drawing itself will now bend along the curve. This has
the advantage that all the problems of flexing with wrong tangents and overflexing disappear. The
downsides are longer computation times (bending an arrow is much more expensive that flexing it, let
alone than quick mode) and also the fact that excessive bending can lead to ugly arrow tips. On the
other hand, for most arrow tips their bend version are visually quite pleasing and create a sophisticated
look:
\begin{tikzpicture}
\wall
\draw [red!25,line width=1mm] (-1,0) -- (1,0);
\draw [red,line width=1mm,-{Stealth[length=20pt,bend]}]
(-1,-.5) .. controls (0,-.5) and (0,0) .. (1,0);
\end{tikzpicture}
196
\begin{tikzpicture}
\wall
\draw [red!25,line width=1mm] (-1,0) -- (1,0);
\draw [red,line width=1mm,-{[bend,sep]»>}]
(-1,-.5) .. controls (0,-.5) and (0,0) .. (1,0);
\end{tikzpicture}
\begin{tikzpicture}
\wall
\draw [red!25,line width=1mm] (-1,0) -- (1,0);
\draw [red,line width=1mm,-{Stealth[bend,round,length=20pt]}]
(0,-.5) .. controls (1,-.5) and (0.25,0) .. (1,0);
\end{tikzpicture}
16.4
Arrow Tip Specifications
16.4.1
Syntax
When you select the arrow tips for the start and the end of a path, you can specify a whole sequence of
arrow tips, each having its own local options. At the beginning of this section, it was pointed out that the
syntax for selecting the start and end arrow tips is the following:
hstart specificationi-hend specificationi
We now have a closer look at what these specifications may look like. The general syntax of the hstart
specificationi is as follows:
[hoptions for all tipsi] hfirst arrow tip speci hsecond arrow tip speci hthird arrow tip speci . . .
As can be seen, an arrow tip specification may start with some options in brackets. If this is the case, the
hoptions for all tipsi will, indeed, be applied to all arrow tips that follow. (We will see, in a moment, that
there are even more places where options may be specified and a list of the ordering in which the options
are applied will be given later.)
The main part of a specification is taken up by a sequence of individual arrow tip specifications. Such a
specification can be of three kinds:
1. It can be of the form harrow tip kind namei[hoptionsi].
2. It can be of the form hshorthand i[hoptionsi].
3. It can be of the form hsingle char shorthand i[hoptionsi]. Note that only for this form the brackets
are optional.
The easiest kind is the first one: This adds an arrow tip of the kind harrow tip kind namei to the sequence
of arrow tips with the hoptionsi applied to it at the start (for the hstart specificationi) or at the end (for the
hend specificationi). Note that for the hstart specificationi the first arrow tip specified in this way will be
at the very start of the curve, while for the hend specificationi the ordering is reversed: The last arrow tip
specified will be at the very end of the curve. This implies that a specification like
Stealth[] Latex[] - Latex[] Stealth[]
will give perfectly symmetric arrow tips on a line (as one would expect).
It is important that even if there are no hoptionsi for an arrow tip, the square brackets still need to be
written to indicate the end of the arrow tip’s name. Indeed, the opening brackets are used to divide the
arrow tip specification into names.
Instead of a harrow tip kind namei, you may also provide the name of a so-called shorthand. Shorthands
look like normal arrow tip kind names and, indeed, you will often be using shorthands without noticing
that you do. The idea is that instead of, say, Computer Modern Rightarrow you might wish to just write
Rightarrow or perhaps just To or even just >. For this, you can create a shorthand that tells Tik Z that
whenever this shorthand is used, another arrow tip kind is meant. (Actually, shorthands are somewhat more
powerful, we have a detailed look at them in Section 16.4.4.) For shorthands, the same rules apply as for
normal arrow tip kinds: You need to provide brackets so that Tik Z can find the end of the name inside a
longer specification.
197
The third kind of arrow tip specifications consist of just a single letter like > or ) or * or even o or x
(but you may not use [, ], or - since they will confuse the parser). These single letter arrow specifications
will invariably be shorthands that select some “real” arrow tip instead. An important feature of single letter
arrow tips is that they do not need to be followed by options (but they may).
Now, since we can use any letter for single letter shorthands, how can Tik Z tell whether by foo[] we
mean an arrow tip kind foo without any options or whether we mean an arrow tip called f, followed by
two arrow tips called o? Or perhaps an arrow tip called f followed by an arrow tip called oo? To solve
this problem, the following rule is used to determine which of the three possible specifications listed above
applies: First, we check whether everything from the current position up to the next opening bracket (or up
to the end) is the name of an arrow tip or of a shorthand. In our case, foo would first be tested under this
rule. Only if foo is neither the name of an arrow tip kind nor of a shorthand does Tik Z consider the first
letter of the specification, f in our case. If this is not the name of a shorthand, an error is raised. Otherwise
the arrow tip corresponding to f is added to the list of arrow tips and the process restarts with the rest.
Thus, we would next text whether oo is the name of an arrow tip or shorthand and, if not, whether o is such
a name.
All of the above rules mean that you can rather easily specify arrow tip sequences if they either mostly
consist of single letter names or of longer names. Here are some examples:
• -»> is interpreted as three times the > shorthand since »> is not the name of any arrow tip kind (and
neither is »).
• ->[]» has the same effect as the above.
• -[]»> also has the same effect.
• ->[]>[]>[] so does this.
• ->Stealth yields an arrow tip > followed by a Stealth arrow at the end.
• -Stealth> is illegal since there is no arrow tip Stealth> and since S is also not the name of any arrow
tip.
• -Stealth[] > is legal and does what was presumably meant in the previous item.
• < Stealth- is legal and is the counterpart to -Stealth[] >.
• -Stealth[length=5pt] Stealth[length=6pt] selects two stealth arrow tips, but at slightly different
sizes for the end of lines.
An interesting question concerns how flexing and bending interact with multiple arrow tips: After all,
flexing and quick mode use different ways of shortening the path so we cannot really mix them. The following
rule is used: We check, independently for the start and the end specifications, whether at least one arrow
tip in them uses one of the options flex, flex’, or bend. If so, all quick settings in the other arrow tips
are ignored and treated as if flex had been selected for them, too.
16.4.2
Specifying Paddings
When you provide several arrow tips in a row, all of them are added to the start or end of the line:
\tikz \draw [«<-»»] (0,0) -- (2,0);
The question is now what will be distance between them? For this, the following arrow key is important:
/pgf/arrow keys/sep=hdimensionihline width factor ihouter factor i
(default 0.88pt .3 1)
When a sequence of arrow tips is specified in an arrow tip specification for the end of the line, the arrow
tips are normally arranged in such a way that the tip of each arrow ends exactly at the “back end” of the
next arrow tip (for start specifications, the ordering is inverted, of course). Now, when the sep option
is set, instead of exactly touching the back end of the next arrow, the specified hdimensioni is added
as additional space (the distance may also be negative, resulting in an overlap of the arrow tips). The
optional factors have the same meaning as for the length key, see that key for details.
Let us now have a look at some examples. First, we use two arrow tips with different separations
between them:
198
\tikz {
\draw [-{>[sep=1pt]>[sep= 2pt]>}] (0,1.0) -- (1,1.0);
\draw [-{>[sep=1pt]>[sep=-2pt]>}] (0,0.5) -- (1,0.5);
\draw [-{>
>[sep]
>}] (0,0.0) -- (1,0.0);
}
You can also specify a sep for the last arrow tip in the sequence (for end specifications, otherwise for
the first arrow tip). In this case, this first arrow tip will not exactly “touch” the point where the path
ends, but will rather leave the specified amount of space. This is usually quite desirable.
A
B
\tikz {
\node [draw] (A) {A};
\node [draw] (B) [right=of A] {B};
\draw [-{»[sep=2pt]}] (A) to [bend left=45] (B);
\draw [- »
] (A) to [bend right=45] (B);
}
Indeed, adding a sep to an arrow tip is very desirable, so you will usually write something like
>={To[sep]} somewhere near the start of your files.
One arrow tip kind can be quite useful in this context: The arrow tip kind _. It draws nothing and has
zero length, but it has sep set as a default option. Since it is a single letter shorthand, you can write
short and clean “code” in this way:
\tikz \draw [->_>] (0,0) -- (1,0);
\tikz \draw [->__>] (0,0) -- (1,0);
However, using the sep option will be faster than using the _ arrow tip and it also allows you to specify
the desired length directly.
16.4.3
Specifying the Line End
In the previous examples of sequences of arrow tips, the line of the path always ended at the last of the
arrow tips (for end specifications) or at the first of the arrow tips (for start specifications). Often, this is
what you may want, but not always. Fortunately, it is quite easy to specify the desired end of the line: The
special single char shorthand . is reserved to indicate that last arrow that is still part of the line; in other
words, the line will stop at the last arrow before . is encountered (for end specifications) are at the first
arrow following . (for start specifications).
\tikz [very thick] \draw [«<-»>] (0,0) -- (2,0);
\tikz [very thick] \draw [<.«->.»] (0,0) -- (2,0);
\tikz [very thick] \draw [«.<-.»>] (0,0) -- (2,0);
\tikz [very thick] \draw [«.<->.»] (0,0) to [bend left] (2,0);
It is permissible that there are several dots in a specification, in this case the first one “wins” (for end
specifications, otherwise the last one).
Note that . is parsed as any other shorthand. In particular, if you wish to add a dot after a normal
arrow tip kind name, you need to add brackets:
\tikz [very thick] \draw [-{Stealth[] . Stealth[] Stealth[]}] (0,0) -- (2,0);
Adding options to . is permissible, but they have no effect. In particular, sep has no effect since a dot
is not an arrow.
199
16.4.4
Defining Shorthands
It is often desirable to create “shorthands” for the names of arrow tips that you are going to use very often.
Indeed, in most documents you will only need a single arrow tip kind and it would be useful that you could
refer to it just as > in your arrow tip specifications. As another example, you might constantly wish to switch
between a filled and a non-filled circle as arrow tips and would like to use * and o are shorthands for these
case. Finally, you might just like to shorten a long name like Computer Modern Rightarrow down to just,
say To or something similar.
All of these case can be addressed by defining appropriate shorthands. This is done using the following
handler:
Key handler hkeyi/.tip=hend specificationi
Defined the hkeyi as a name that can be used inside arrow tip specifications. If the hkeyi has a path before
it, this path is ignored (so there is only one “namespace” for arrow tips). Whenever it is used, it will
be replaced by the hend specificationi. Note that you must always provide (only) an end specification;
when the hkeyi is used inside a start specification, the ordering and the meaning of the keys inside the
hend specificationi are translated automatically.
\tikz [foo /.tip = {Stealth[sep]. »}]
\draw [-foo] (0,0) -- (2,0);
\tikz [foo /.tip = {Stealth[sep] Latex[sep]},
bar /.tip = {Stealth[length=10pt,open]}]
\draw [-{foo[red] . bar}] (0,0) -- (2,0);
In the last of the examples, we used foo[red] to make the arrows red. Any options given to a shorthand upon use will be passed on to the actual arrows tip for which the shorthand stands. Thus, we
could also have written Stealth[sep,red] Latex[sep,red] instead of foo[red]. In other words, the
“replacement” of a shorthand by its “meaning” is a semantic replacement rather than a syntactic replacement. In particular, the hend specificationi will be parsed immediately when the shorthand is being
defined. However, this applies only to the options inside the specification, whose values are evaluated
immediately. In contrast, which actual arrow tip kind is meant by a given shorthand used inside the
hend specificationi is resolved only up each use of the shorthand. This means that when you write
dup /.tip = »
and then later write
> /.tip = whatever
then dup will have the effect as if you had written whatever[]whatever[]. You will find that this
behaviour is what one would expect.
There is one problem we have not yet addressed: The asymmetry of single letter arrow tips like > or ).
When someone writes
\tikz \draw [<->] (0,0) -- (1,0);
we rightfully expect one arrow tip pointing left at the left end and an arrow tip pointing right at the
right end. However, compare
\tikz \draw [>->] (0,0) -- (1,0);
\tikz \draw [Stealth-Stealth] (0,0) -- (1,0);
In both cases, we have identical text in the start and end specifications, but in the first case we rightfully
expect the left arrow to be flipped.
The solution to this problem is that it is possible to define two names for the same arrow tip, namely
one that is used inside start specifications and one for end specifications. Now, we can decree that the
“name of >” inside start specifications is simply < and the above problems disappear.
To specify different names for a shorthand in start and end specifications, use the following syntax:
Instead of hkeyi, you use hname in start specificationsi-hname in end specificationsi. Thus, to set the
> key correctly, you actually need to write
200
\tikz [<-> /.tip = Stealth] \draw [<-»] (0,0) -- (1,0);
\tikz [<-> /.tip = Latex] \draw [>-<] (0,0) -- (1,0);
Note that the above also works even though we have not set < as an arrow tip name for end specifications!
The reason this works is that the Tik Z (more precisely, pgf) actually uses the following definition
internally:
>-< /.tip = >[reversed]
Translation: “When < is used in an end specification, please replace it by >, but reversed. Also, when >
is used in a start specification, we also mean this inverted >.”
By default, > is a shorthand for To and To is a shorthand for to (an arrow from the old libraries) when
arrows.meta is not loaded library. When arrow.meta is loaded, To is redefined to mean the same as
Computer Modern Rightarrow.
/tikz/>=hend arrow specificationi
(no default)
This is a short way of saying <->/.tip=hend arrow specificationi.
\begin{tikzpicture}[scale=2,ultra thick]
\begin{scope}[>=Latex]
\draw[>->]
(0pt,3ex) -- (1cm,3ex);
\draw[|<-»|] (0pt,2ex) -- (1cm,2ex);
\end{scope}
\begin{scope}[>=Stealth]
\draw[>->]
(0pt,1ex) -- (1cm,1ex);
\draw[|«.<->|] (0pt,0ex) -- (1cm,0ex);
\end{scope}
\end{tikzpicture}
16.4.5
Scoping of Arrow Keys
There are numerous places where you can specify keys for an arrow tip. There is, however, one final place
that we have not yet mentioned:
/tikz/arrows=[harrow keysi]
(no default)
The arrows key, which is normally used to set the arrow tips for the current scope, can also be used
to set some arrow keys for the current scope. When the argument to arrows starts with an opening
bracket and only otherwise contains one further closing bracket at the very end, this semantic of the
arrow key is assumed.
The harrow keysi will be set for the rest of current scope. This is useful for generally setting some design
parameters or for generally switching on, say, bending as in:
\tikz [arrows={[bend]}] ... % Bend all arrows
We can now summarize which arrow keys are applied in what order when an arrow tip is used:
1. First, the so-called defaults are applied, which are values for the different parameters of a key. They
are fixed in the definition of the key and cannot be changed. Since they are executed first, they are
only the ultimate fallback.
2. The hkeysi from the use of arrows=[]hkeysi] in all enclosing scopes.
3. Recursively, the hkeysi provided with the arrow tip inside shorthands.
4. The keys provided at the beginning of an arrow tip specification in brackets.
5. The keys provided directly next to the arrow tip inside the specification.
201
16.5
Reference: Arrow Tips
Tik Z Library arrows.meta
\usepgflibrary{arrows.meta}
\usepgflibrary[arrows.meta]
\usetikzlibrary{arrows.meta}
\usetikzlibrary[arrows.meta]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library defines a large number of standard “meta” arrow tips. “Meta” means that you can configure
these arrow tips in many different ways like changing their size or their line caps and joins and many
other details.
The only reason this library is not loaded by default is for compatibility with older versions of Tik Z. You
can, however, safely load and use this library alongside the older libraries arrows and arrows.spaced.
The different arrow tip kinds defined in the arrows.meta library can be classified in different groups:
• Barbed arrow tips consist mainly of lines that “point backward” from the tip of the arrow and which
are not filled. For them, filling has no effect. A typical example is
. Here is the list of defined arrow
tips:
Appearance of the below at line width
0.4pt
0.8pt
1.6pt
thick
thick
thick
thick
thick
thick
thick
thin
thin
thin
thin
thin
thin
thin
Arc Barb[]
Bar[]
Bracket[]
Hooks[]
Parenthesis[]
Straight Barb[]
Tee Barb[]
All of these arrow tips can be configured and resized in many different ways as described in the
following. Above, they are shown at their “natural” sizes, which are chosen in such a way that for a
line width of 0.4pt their width matches the height of a letter “x” in Computer Modern at 11pt (with
some “overshooting” to create visual consistency).
• Mathematical arrow tips are actually a subclass of the barbed arrow tips, but we list them separately.
They contain arrow tips that look exactly like the tips of arrows used in mathematical fonts such as
the \to-symbol → from standard TEX.
Appearance of the below at line width
0.4pt
0.8pt
1.6pt
thick
thick
thick
thick
thin
thin
thin
thin
Classical TikZ Rightarrow[]
Computer Modern Rightarrow[]
Implies[] on double line
To[]
The To arrow tip is a shorthand for Computer Modern Rightarrow when arrows.meta is loaded.
• Geometric arrow tips consist of a filled shape like a kite or a circle or a “stealth-fighter-like” shape. A
typical example is
. These arrow tips can also be used in an “open” variant as in
.
Appearance of the below at line width
0.4pt
0.8pt
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
Circle[]
Diamond[]
Ellipse[]
Kite[]
Latex[]
Latex[round]
Rectangle[]
Square[]
Stealth[]
Stealth[round]
202
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thin
thin
Triangle[]
Turned Square[]
Here are the “open” variants:
Appearance of the below at line width
0.4pt
0.8pt
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
Circle[open]
Diamond[open]
Ellipse[open]
Kite[open]
Latex[open]
Latex[round,open]
Rectangle[open]
Square[open]
Stealth[open]
Stealth[round,open]
Triangle[open]
Turned Square[open]
Note that “open” arrow tips are not the same as “filled with white,” which is also available (just say
fill=white). The difference is that the background will “shine through” an open arrow, while a filled
arrow always obscures the background:
\tikz {
\shade [left color=white, right color=red!50] (0,0) rectangle (4,1);
\draw [ultra thick,-{Triangle[open]}]
(0,2/3) -- ++ (3,0);
\draw [ultra thick,-{Triangle[fill=white]}] (0,1/3) -- ++ (3,0);
}
• Cap arrow tips are used to add a “cap” to the end of a line. The graphic languages underlying Tik Z
(pdf, postscript or svg) all support three basic types of line caps on a very low level: round,
rectangular, and “butt.” Using cap arrow tips, you can add new caps to lines and use different caps
for the end and the start. An example is the line
.
Appearance of the below at line width
1ex
1em
Butt Cap[]
Fast Round[]
Fast Triangle[]
Round Cap[]
Triangle Cap[]
• Special arrow tips are used for some specific purpose and do not fit into the above categories.
Appearance of the below at line width
0.4pt
1.6pt
thick
thick
Barbed Arrow Tips
Arrow Tip Kind Arc Barb
length
This arrow tip attaches an arc to the end of the line whose angle is
given by the arc option. The length and width parameters refer
to the size of the arrow tip for arc set to 180 degrees, which is
why in the example for arc=210 the actual length is larger than
the specified length. The line width is taken into account for the
computation of the length and width. Use the round option to add
round caps to the end of the arcs.
203
width
16.5.1
0.8pt
thin
thin
Rays[]
Rays[n=8]
Appearance of the below at line width
Arc
Arc
Arc
Arc
Arc
Arc
Arc
Arc
Arc
Arc
Arc
Arc
Arc
Arc
Arc
0.4pt
0.8pt
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
Barb[]
Barb[sep] Arc Barb[]
Barb[sep] . Arc Barb[]
Barb[arc=120]
Barb[arc=270]
Barb[length=2pt]
Barb[length=2pt,width=5pt]
Barb[line width=2pt]
Barb[reversed]
Barb[round]
Barb[slant=.3]
Barb[left]
Barb[right]
Barb[harpoon,reversed]
Barb[red]
The following options have no effect: open, fill.
On double lines, the arrow tip will not look correct.
Arrow Tip Kind Bar
A simple bar. This is a simple instance of Tee Barb for length zero.
Arrow Tip Kind Bracket
This is an instance of the TeeBarb arrow tip that results in something resembling a bracket. Just like the Parenthesis arrow tip, a
Bracket is not modelled from a text square bracket, but rather its
size has been chosen so that it fits with the other arrow tips.
Appearance of the below at line width
0.4pt
0.8pt
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
Bracket[]
Bracket[sep] Bracket[]
Bracket[sep] . Bracket[]
Bracket[reversed]
Bracket[round]
Bracket[slant=.3]
Bracket[left]
Bracket[right]
Bracket[harpoon,reversed]
Bracket[red]
The following options have no effect: open, fill.
On double lines, the arrow tip will not look correct.
Arrow Tip Kind Hooks
length
Appearance of the below at line width
width
This arrow tip attaches two “hooks” to the end of the line. The
length and width parameters refer to the size of the arrow tip if
both arcs are 180 degrees; in the example the arc is 210 degrees and,
thus, the arrow is actually longer that the length dictates. The line
width is taken into account for the computation of the length and
width. The arc option is used to specify the angle of the arcs. Use
the round option to add round caps to the end of the arcs.
0.4pt
0.8pt
thin
thin
thin
thin
Hooks[]
Hooks[sep] Hooks[]
Hooks[sep] . Hooks[]
Hooks[arc=120]
204
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
Hooks[arc=270]
Hooks[length=2pt]
Hooks[length=2pt,width=5pt]
Hooks[line width=2pt]
Hooks[reversed]
Hooks[round]
Hooks[slant=.3]
Hooks[left]
Hooks[right]
Hooks[harpoon,reversed]
Hooks[red]
The following options have no effect: open, fill.
On double lines, the arrow tip will not look correct.
Arrow Tip Kind Parenthesis
This arrow tip is an instantiation of the ArcBarb so that it resembles a parenthesis. However, the idea is not to recreate a “real”
parenthesis as it is used in text, but rather a “bow” at a size that
harmonizes with the other arrow tips at their default sizes.
Appearance of the below at line width
0.4pt
0.8pt
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
Parenthesis[]
Parenthesis[sep] Parenthesis[]
Parenthesis[sep] . Parenthesis[]
Parenthesis[reversed]
Parenthesis[round]
Parenthesis[slant=.3]
Parenthesis[left]
Parenthesis[right]
Parenthesis[harpoon,reversed]
Parenthesis[red]
The following options have no effect: open, fill.
On double lines, the arrow tip will not look correct.
Arrow Tip Kind Straight Barb
length
Appearance of the below at line width
Straight
Straight
Straight
Straight
Straight
Straight
Straight
Straight
Straight
Straight
Straight
Straight
width
This is the “archetypal” arrow head, consisting of just two straight
lines. The length and width parameters refer to the horizontal
and vertical distances between the points on the path making up
the arrow tip. As can be seen, the line width of the arrow tip’s path
is not taken into account. The angle option is particularly useful
to set the opening angle at the tip of the arrow head. The round
option gives a “softer” or “rounder” version of the arrow tip.
0.4pt
0.8pt
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
Barb[]
Barb[] Straight Barb[]
Barb[] . Straight Barb[]
Barb[length=5pt]
Barb[length=5pt,width=5pt]
Barb[line width=2pt]
Barb[reversed]
Barb[angle=60:2pt 3]
Barb[round]
Barb[slant=.3]
Barb[left]
Barb[right]
205
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thin
thin
Straight Barb[harpoon,reversed]
Straight Barb[red]
The following options have no effect: open, fill.
On double lines, the arrow tip will not look correct.
Arrow Tip Kind Tee Barb
length
width
This arrow tip attaches a little “T” on both sides of the tip. The
arrow inset dictates the distance from the back end to the middle
of the stem of the T. When the inset is equal to the length, the arrow
tip is drawn as a single line, not as three lines (this is important for
the “round” version since, then, the corners get rounded).
inset
Appearance of the below at line width
Tee
Tee
Tee
Tee
Tee
Tee
Tee
Tee
Tee
Tee
Tee
Tee
Tee
0.4pt
0.8pt
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
Barb[]
Barb[sep] Tee Barb[]
Barb[sep] . Tee Barb[]
Barb[inset=0pt]
Barb[inset’=0pt 1]
Barb[line width=2pt]
Barb[round]
Barb[round,inset’=0pt 1]
Barb[slant=.3]
Barb[left]
Barb[right]
Barb[harpoon,reversed]
Barb[red]
The following options have no effect: open, fill.
On double lines, the arrow tip will not look correct.
16.5.2
Mathematical Barbed Arrow Tips
Arrow Tip Kind Classical TikZ Rightarrow
length
width
This arrow tip is the “old” or “classical” arrow tip that used to
be the standard in Tik Z in earlier versions. It was modelled on an
old version of the tip of \rightarrow (→) of the Computer Modern
fonts. However, this “old version” was really old, Donald Knuth (the
designer of both TEX and of the Computer Modern fonts) replaced
the arrow tip of the mathematical fonts in 1992.
The main problem with this arrow tip is that it is “too small” at its natural size. I recommend using the
new Computer Modern Rightarrow arrow tip instead, which matches the current →. This new version
is also the default used as > and as To, now.
Appearance of the below at line width
Classical
Classical
Classical
Classical
Classical
Classical
Classical
Classical
Classical
Classical
TikZ
TikZ
TikZ
TikZ
TikZ
TikZ
TikZ
TikZ
TikZ
TikZ
0.4pt
Rightarrow[]
Rightarrow[sep] Classical TikZ Rightarrow[]
Rightarrow[sep] . Classical TikZ Rightarrow[]
Rightarrow[length=3pt]
Rightarrow[sharp]
Rightarrow[slant=.3]
Rightarrow[left]
Rightarrow[right]
Rightarrow[harpoon,reversed]
Rightarrow[red]
206
0.8pt
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
The following options have no effect: open, fill.
On double lines, the arrow tip will not look correct.
Arrow Tip Kind Computer Modern Rightarrow
length
Appearance of the below at line width
Computer
Computer
Computer
Computer
Computer
Computer
Computer
Computer
Computer
Computer
Modern
Modern
Modern
Modern
Modern
Modern
Modern
Modern
Modern
Modern
width
For a line width of 0.4pt (the default), this arrow tip looks very
much like \rightarrow (→) of the Computer Modern math fonts.
However, it is not a “perfect” match: the line caps and joins of the
“real” → are rounded differently from this arrow tip; but it takes a
keen eye to notice the difference. When the arrow.meta library is
loaded, this arrow tip becomes the default of To and, thus, is used
whenever > is used (unless, of course, you redefined >).
0.4pt
0.8pt
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
Rightarrow[]
Rightarrow[sep] Computer Modern Rightarrow[]
Rightarrow[sep] . Computer Modern Rightarrow[]
Rightarrow[length=3pt]
Rightarrow[sharp]
Rightarrow[slant=.3]
Rightarrow[left]
Rightarrow[right]
Rightarrow[harpoon,reversed]
Rightarrow[red]
The following options have no effect: open, fill.
On double lines, the arrow tip will not look correct.
Arrow Tip Kind Implies
This arrow tip makes only sense in conjunction with the double option. The idea is that you attach it
to a double line to get something that looks like TEX’s \implies arrow ( =⇒ ). A typical use of this
arrow tip is
α
γ
β
\tikz \graph [clockwise=3, math nodes,
edges = {double equal sign distance, -Implies}] {
"\alpha", "\beta", "\gamma";
"\alpha" -> "\beta" -> "\gamma" -> "\alpha"
};
Appearance of the below at line width
0.4pt
0.8pt
1.6pt
thick
thick
thin
thin
Implies[] on double line
Implies[red] on double line
Arrow Tip Kind To
This is a shorthand for Computer Modern Rightarrow when the arrow.meta library is loaded. Otherwise, it is a shorthand for the classical Tik Z rightarrow.
16.5.3
Geometric Arrow Tips
Arrow Tip Kind Circle
length
Appearance of the below at line width
width
Although this tip is called “circle,” you can also use it to draw
ellipses if you set the length and width to different values. Neither
round nor reversed has any effect on this arrow tip.
0.4pt
0.8pt
thin
thin
Circle[]
Circle[sep] Circle[]
207
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thin
thin
thin
thin
thin
thin
thin
Circle[sep] . Circle[]
Circle[open]
Circle[length=3pt]
Circle[slant=.3]
Circle[left]
Circle[right]
Circle[red]
Arrow Tip Kind Diamond
This is an instance of Kite where the length is larger than the width.
Appearance of the below at line width
0.4pt
0.8pt
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
Diamond[]
Diamond[] Diamond[]
Diamond[] . Diamond[]
Diamond[open]
Diamond[length=10pt]
Diamond[round]
Diamond[slant=.3]
Diamond[left]
Diamond[right]
Diamond[red]
Diamond[fill=red!50]
Arrow Tip Kind Ellipse
This is a shorthand for a “circle” that is twice as wide as high.
Appearance of the below at line width
0.4pt
0.8pt
Arrow Tip Kind Kite
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
Ellipse[]
Ellipse[sep] Ellipse[]
Ellipse[sep] . Ellipse[]
Ellipse[open]
Ellipse[length=10pt]
Ellipse[round]
Ellipse[slant=.3]
Ellipse[left]
Ellipse[right]
Ellipse[red]
Ellipse[fill=red!50]
length
width
This arrow tip consists of four lines that form a “kite.” The inset
prescribed how far the width-axis of the kite is removed from the
back end. Note that the inset cannot be negative, use a Stealth
arrow tip for this.
inset
Appearance of the below at line width
0.4pt
0.8pt
thin
thin
thin
thin
thin
thin
thin
Kite[]
Kite[sep] Kite[]
Kite[sep] . Kite[]
Kite[open]
Kite[length=6pt,width=4pt]
Kite[length=6pt,width=4pt,inset=1.5pt]
Kite[round]
208
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thin
thin
thin
thin
Kite[slant=.3]
Kite[left]
Kite[right]
Kite[red]
Arrow Tip Kind Latex
length
Appearance of the below at line width
width
This arrow tip is the same as the arrow tip used in LATEX’s standard
pictures (via the \vec command), if you set the length to 4pt. The
default size for this arrow tip was set slightly larger so that it fits
better with the other geometric arrow tips.
0.4pt
0.8pt
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
Latex[]
Latex[sep] Latex[]
Latex[sep] . Latex[]
Latex[open]
Latex[length=4pt]
Latex[round]
Latex[slant=.3]
Latex[left]
Latex[right]
Latex[red]
Arrow Tip Kind LaTeX
Another spelling for the Latex arrow tip.
Arrow Tip Kind Rectangle
length
width
A rectangular arrow tip. By default, it is twice as long as high.
Appearance of the below at line width
0.4pt
0.8pt
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
Rectangle[]
Rectangle[sep] Rectangle[]
Rectangle[sep] . Rectangle[]
Rectangle[open]
Rectangle[length=4pt]
Rectangle[round]
Rectangle[slant=.3]
Rectangle[left]
Rectangle[right]
Rectangle[red]
Arrow Tip Kind Square
An instance of the Rectangle whose width is identical to the length.
Appearance of the below at line width
0.4pt
0.8pt
thin
thin
thin
thin
thin
thin
Square[]
Square[sep] Square[]
Square[sep] . Square[]
Square[open]
Square[length=4pt]
Square[round]
209
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thin
thin
thin
thin
Square[slant=.3]
Square[left]
Square[right]
Square[red]
Arrow Tip Kind Stealth
length
width
This arrow tip is similar to a Kite, only the inset now counts
“inwards.” Because of that sharp angles, for this arrow tip is makes
quite a difference, visually, if use the round option. Also, using
the harpoon option (or left or right) will lengthen the arrow tip
because of the even sharper corner at the tip.
inset
Appearance of the below at line width
0.4pt
0.8pt
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
Stealth[]
Stealth[sep] Stealth[]
Stealth[sep] . Stealth[]
Stealth[open]
Stealth[length=6pt,width=4pt]
Stealth[length=6pt,width=4pt,inset=1.5pt]
Stealth[round]
Stealth[slant=.3]
Stealth[left]
Stealth[right]
Stealth[red]
Arrow Tip Kind Triangle
An instance of a Kite with zero inset.
Appearance of the below at line width
0.4pt
0.8pt
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
Triangle[]
Triangle[sep] Triangle[]
Triangle[sep] . Triangle[]
Triangle[open]
Triangle[length=4pt]
Triangle[angle=45:1pt 3]
Triangle[angle=60:1pt 3]
Triangle[angle=90:1pt 3]
Triangle[round]
Triangle[slant=.3]
Triangle[left]
Triangle[right]
Triangle[red]
Arrow Tip Kind Turned Square
An instance of a Kite with identical width and height and mid-inset.
Appearance of the below at line width
Turned
Turned
Turned
Turned
Turned
Turned
Turned
Turned
0.4pt
0.8pt
thin
thin
thin
thin
thin
thin
thin
thin
Square[]
Square[sep] Turned Square[]
Square[sep] . Turned Square[]
Square[open]
Square[length=4pt]
Square[round]
Square[slant=.3]
Square[left]
210
1.6pt
thick
thick
thick
thick
thick
thick
thick
thick
16.5.4
thick
thick
thin
thin
Turned Square[right]
Turned Square[red]
Caps
Recall that a cap is a way of ending a line. The graphic languages underlying Tik Z (pdf, postscript or
svg) all support three basic types of line caps on a very low level: round, rectangular, and “butt.” Using
cap arrow tips, you can add new caps to lines and use different caps for the end and the start.
Arrow Tip Kind Butt Cap
This arrow tip ends the line “in the normal way” with a straight end. This arrow tip is only need to
“cover up” the actual line cap, if this happens to differ from the normal cap. In the following example,
the line cap is “round”, but, nevertheless, the right end is a “butt” cap:
\tikz \draw [line width=1ex, line cap=round, -Butt Cap] (0,0) -- (1,0);
Arrow Tip Kind Fast Round
length
This arrow tip is not really a cap, you use it in conjunction with
(typically) the RoundCap. The idea is that you end your line using
the round cap and then add several Fast Rounds. As for RoundCap,
the length parameter dictates the length is the length of the “main
part,” the inset sets the length of a line that comes before this tip.
inset
\tikz \draw [line width=1ex,
-{Round Cap []. Fast Round[] Fast Round[]}]
(0,0) -- (1,0);
Note that in conjunction with the bend option, this works even quite well for curves:
\tikz [f/.tip = Fast Round] % shorthand
\draw [line width=1ex, -{[bend] Round Cap[] . f f f}]
(0,0) to [bend left] (1,0);
Appearance of the below at line width
Fast
Fast
Fast
Fast
Fast
Fast
1ex
1em
Round[]
Round[reversed]
Round[cap angle=60]
Round[cap angle=60,inset=5pt]
Round[length=.5ex]
Round[slant=.3]
Arrow Tip Kind Fast Triangle
length
This arrow tip works like FastRound, only for triangular caps.
inset
\tikz \draw [line width=1ex,
-{Triangle Cap []. Fast Triangle[] Fast Triangle[]}]
(0,0) -- (1,0);
Again, this tip works well for curves:
\tikz [f/.tip = Fast Triangle] % shorthand
\draw [line width=1ex, -{[bend] Triangle Cap[] . f f f}]
(0,0) to [bend left] (1,0);
211
Appearance of the below at line width
Fast
Fast
Fast
Fast
Fast
Fast
1ex
1em
Triangle[]
Triangle[reversed]
Triangle[cap angle=60]
Triangle[cap angle=60,inset=5pt]
Triangle[length=.5ex]
Triangle[slant=.3]
Arrow Tip Kind Round Cap
length
This arrow tip ends the line using a half circle or, if the length has
been modified, a half-ellipse.
Appearance of the below at line width
Round
Round
Round
Round
1ex
1em
Cap[]
Cap[reversed]
Cap[length=.5ex]
Cap[slant=.3]
Arrow Tip Kind Triangle Cap
length
This arrow tip ends the line using a triangle whose length is given
by the length option.
You can get any angle you want at the tip by specifying a length that is an appropriate multiple of the
line width. The following options does this computation for you:
(no default)
/pgf/arrow keys/cap angle=hanglei
Sets length to an appropriate multiple of the line width so that the angle of a Triangle Cap is
exactly hanglei at the tip.
Appearance of the below at line width
Triangle
Triangle
Triangle
Triangle
Triangle
Triangle
16.5.5
1ex
1em
Cap[]
Cap[reversed]
Cap[cap angle=60]
Cap[cap angle=60,reversed]
Cap[length=.5ex]
Cap[slant=.3]
Special Arrow Tips
Arrow Tip Kind Rays
length
Appearance of the below at line width
width
This arrow tip attaches a “bundle of rays” to the tip. The number
of evenly spaced rays is given by the n arrow key (see below). When
the number is even, the rays will lie to the left and to the right of
the direction of the arrow; when the number is odd, the rays are
rotated in such a way that one of them points perpendicular to the
direction of the arrow (this is to ensure that no ray points in the
direction of the line, which would look strange). The length and
width describe the length and width of an ellipse into which the
rays fit.
0.4pt
0.8pt
1.6pt
Rays[]
Rays[sep] Rays[]
Rays[sep] . Rays[]
thin
thin
thin
thick
thick
thick
Rays[width’=0pt 2]
thin
thick
212
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
thin
Rays[round]
Rays[n=2]
Rays[n=3]
Rays[n=4]
Rays[n=5]
Rays[n=6]
Rays[n=7]
Rays[n=8]
Rays[n=9]
Rays[slant=.3]
Rays[left]
Rays[right]
Rays[left,n=5]
Rays[right,n=5]
Rays[red]
/pgf/arrow keys/n=hnumber i
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
thick
(no default, initially 4)
Sets the number of rays in a Rays arrow tip.
213
17
Nodes and Edges
17.1
Overview
In the present section, the usage of nodes in Tik Z is explained. A node is typically a rectangle or circle or
another simple shape with some text on it.
Nodes are added to paths using the special path operation node. Nodes are not part of the path itself.
Rather, they are added to the picture just before or after the path has been drawn.
In Section 17.2 the basic syntax of the node operation is explained, followed in Section 17.3 by the syntax
for multi-part nodes, which are nodes that contain several different text parts. After this, the different
options for the text in nodes are explained. In Section 17.5 the concept of anchors is introduced along
with their usage. In Section 17.7 the different ways transformations affect nodes are studied. Sections 17.8
and 17.9 are about placing nodes on or next to straight lines and curves. Section 17.11 explains how a node
can be used as a “pseudo-coordinate.” Section 17.12 introduces the edge operation, which works similar to
the to operation and also similar to the node operation.
17.2
Nodes and Their Shapes
In the simplest case, a node is just some text that is placed at some coordinate. However, a node can also
have a border drawn around it or have a more complex background and foreground. Indeed, some nodes do
not have a text at all, but consist solely of the background. You can name nodes so that you can reference
their coordinates later in the same picture or, if certain precautions are taken as explained in Section 17.13,
also in different pictures.
There are no special TEX commands for adding a node to a picture; rather, there is path operation called
node for this. Nodes are created whenever Tik Z encounters node or coordinate at a point on a path where
it would expect a normal path operation (like --(1,1) or rectangle (1,1)). It is also possible to give node
specifications inside certain path operations as explained later.
The node operation is typically followed by some options, which apply only to the node. Then, you can
optionally name the node by providing a name in parentheses. Lastly, for the node operation you must
provide some label text for the node in curly braces, while for the coordinate operation you may not. The
node is placed at the current position of the path either after the path has been drawn or (more seldomly
and only if you add the behind path option) just before the path is drawn. Thus, all nodes are drawn “on
top” or “behind” the path and are retained until the path is complete. If there are several nodes on a path,
perhaps some behind and some on top of the path, first come the nodes behind the path in the order they
were encountered, then comes that path, and then come the remaining node, again in the order they are
encountered.
second node
first node
17.2.1
third node
\tikz \fill [fill=yellow!80!black]
(0,0) node
{first node}
-- (1,1) node[behind path] {second node}
-- (2,0) node
{third node};
Syntax of the Node Command
The syntax for specifying nodes is the following:
\path . . . nodehforeach statementsi[hoptionsi](hnamei)at(hcoordinatei){hnode contentsi} . . . ;
Since this path operation is one of the most involved around, let us go over it step by step.
Order of the parts of the specification. Everything between “node” and the opening brace of a node
is optional. If there are hforeach statementsi, they must come first, directly following “node.” Other
than that, the ordering of all the other elements of a node specification (the hoptionsi, the hnamei, and
hcoordinatei) is arbitrary, indeed, there can be multiple occurrences of any of these elements (although
only for options this makes much sense).
The text of a node. At the end of a node, you must (normally) provide some hnode contentsi in
curly braces; indeed, the “end” of the node specification is detected by the opening curly brace. For
normal nodes it is possible to use “fragile” stuff inside the hnode contentsi like the \verb command (for
the technically savvy: code inside the hnode contentsi is allowed to change catcodes; however, this rule
does not apply to “nodes on a path” to be discussed later).
214
Instead of giving hnode contentsi at the end of the node in curly braces, you can also use the following
key:
/tikz/node contents=hnode contentsi
(no default)
This key sets the contents of the node to the given text as if you had given it at the end in
curly braces. When the option is used inside the options of a node, the parsing of the node stops
immediately after the end of the option block. In particular, the option block cannot be followed by
further option blocks or curly braces (or, rather, these do not count as part of the node specification.)
Also note that the hnode contentsi may not contain fragile stuff since the catcodes get fixed upon
reading the options. Here is an example:
A
B
C
D
\tikz {
\path (0,0)
(1,0)
(2,0)
(3,0)
}
node
node
node
node
[red]
{A}
[blue]
{B}
[green, node contents=C]
[node contents=D]
;
Specifying the location of the node. Nodes are placed at the last position mentioned on the path.
The effect of adding “at” to a node specification is that the coordinate given after at is used instead.
The at syntax is not available when a node is given inside a path operation (it would not make any
sense there).
/tikz/at=hcoordinatei
(no default)
This is another way of specifying the at coordinate. Note that, typically, you will have to enclose
the hcoordinatei in curly braces so that a comma inside the hcoordinatei does not confuse TEX.
Another aspect of the “location” of a node is whether it appears in front of or behind the current path.
You can change which of these two possibilities happens on a node-by-node basis using the following
keys:
(no value)
/tikz/behind path
When this key is set, either as a local option for the node or some surrounding scope, the node will
be drawn behind the current path. For this, Tik Z collects all nodes defined on the current path
with this option set and then inserts all of them, in the order they appear, just before it draws the
path. Thus, several nodes with this option set may obscure one anther, but never the path itself.
“Just before it draws the path” actually means that the nodes are inserted into the page output
just before any pre-actions are applied to the path (see below for what pre-actions are).
fourth node
third node
first nodesecond node
\tikz \fill [fill=blue!50,
(0,0)
node [behind
-- (1.5,0) node [behind
-- (1.5,1) node [behind
-- (0,1)
node [
draw=blue, very thick]
path, fill=red!50]
{first node}
path, fill=green!50] {second node}
path, fill=brown!50] {third node}
fill=blue!30] {fourth node};
Note that behind path only applies to the current path; not to the current scope or picture. To
put a node “behind everything” you need to use layers and options like on background layer, see
the background library in Section 43.
(no value)
/tikz/in front of path
This is the opposite of behind path: It causes nodes to be drawn on top of the path. Since this
is the default behaviour, you usually do not need this option; it is only needed when an enclosing
scope has used behind path and you now wish to “switch back” to the normal behaviour.
The name of a node. The (hnamei) is a name for later reference and it is optional. You may also
add the option name=hnamei to the hoptioni list; it has the same effect.
/tikz/name=hnode namei
(no default)
Assigns a name to the node for later reference. Since this is a “high-level” name (drivers never
know of it), you can use spaces, number, letters, or whatever you like when naming a node. Thus,
you can name a node just 1 or perhaps start of chart or even y_1. Your node name should not
215
contain any punctuation like a dot, a comma, or a colon since these are used to detect what kind
of coordinate you mean when you reference a node.
/tikz/alias=hanother node namei
(no default)
This option allows you to provide another name for the node. Giving this option multiple times
will allow you to access the node via several aliases. Using the node also syntax, you can also
assign an alias name to a node at a later point, see Section 17.14.
The options of a node. The hoptionsi is an optional list of options that apply only to the node and
have no effect outside. The other way round, most “outside” options also apply to the node, but not
all. For example, the “outside” rotation does not apply to nodes (unless some special options are used,
sigh). Also, the outside path action, like draw or fill, never applies to the node and must be given in
the node (unless some special other options are used, deep sigh).
The shape of a node. As mentioned before, we can add a border and even a background to a node:
third node
second node
\tikz \fill[fill=yellow!80!black]
(0,0) node {first node}
-- (1,1) node[draw, behind path] {second node}
-- (0,2) node[fill=red!20,draw,double,rounded corners] {third node};
first node
The “border” is actually just a special case of a much more general mechanism. Each node has a certain
shape which, by default, is a rectangle. However, we can also ask Tik Z to use a circle shape instead or
an ellipse shape (you have to include one of the shapes.geometric library for the latter shape):
\tikz \fill[fill=yellow!80!black]
(0,0) node
{first node}
-- (1,1) node[ellipse,draw, behind path] {second node}
-- (0,2) node[circle,fill=red!20]
{third node};
third node
second node
first node
There are many more shapes available such as, say, a shape for a resistor or a large arrow, see the
shapes library in Section 67 for details.
To select the shape of a node, the following option is used:
/tikz/shape=hshape namei
(no default, initially rectangle)
Select the shape either of the current node or, when this option is not given inside a node but
somewhere outside, the shape of all nodes in the current scope.
Since this option is used often, you can leave out the shape=. When Tik Z encounters an option like
circle that it does not know, it will, after everything else has failed, check whether this option is
the name of some shape. If so, that shape is selected as if you had said shape=hshape namei.
By default, the following shapes are available: rectangle, circle, coordinate. Details of these
shapes, like their anchors and size options, are discussed in Section 17.2.2.
The foreach statement for nodes. At the beginning of a node specification (and only there) you can
provide multiple hforeach statementsi, each of which has the form foreach hvar i in {hlisti} (note that
there is no slash before foreach). When they are given, instead of a single node, multiple nodes will
be created: The hvar i will iterate over all values of hlisti and for each of them, a new node is created.
These nodes are all created using all the text following the hforeach statementsi, but in each copy the
hvar i will have the current value of the current element in the hlisti.
As an example, the following two codes have the same effect:
1
2
3
\tikz \draw (0,0) node foreach \x in {1,2,3} at (\x,0) {\x};
216
1
2
3
\tikz \draw (0,0) node at (1,0) {1} node at (2,0) {2} node at (3,0) {3};
When you provide several foreach statements, they work like “nested loops”:
1,3
2,3
3,3
4,3
1,2
2,2
3,2
4,2
1,1
2,1
3,1
4,1
\tikz \node foreach \x in {1,...,4} foreach \y in {1,2,3}
[draw] at (\x,\y) {\x,\y};
As the example shows, a hlisti can contain ellipses (three dots) to indicated that a larger number of
numbers is meant. Indeed, you can use the full power of the \foreach command here, including multiple
parameters and options, see Section 83.
Styles for nodes. The following styles influence how nodes are rendered:
(style, initially empty)
/tikz/every node
This style is installed at the beginning of every node.
B
\begin{tikzpicture}[every node/.style={draw}]
\draw (0,0) node {A} -- (1,1) node {B};
\end{tikzpicture}
A
/tikz/every hshape i node
(style, initially empty)
These styles are installed at the beginning of a node of a given hshapei. For example, every
rectangle node is used for rectangle nodes, and so on.
B
A
\begin{tikzpicture}
[every rectangle node/.style={draw},
every circle node/.style={draw,double}]
\draw (0,0) node[rectangle] {A} -- (1,1) node[circle] {B};
\end{tikzpicture}
Name scopes. It turns out that the name of a node can further be influenced using two keys:
(no default, initially empty)
/tikz/name prefix=htexti
The value of this key is prefixed to every node inside the current scope. This includes both the
naming of the node (via the name key or via the implicit (hnamei) syntax) as well as any referencing
of the node. Outside the scope, the nodes can (and need to) be referenced using “full name”
consisting of the prefix and the node name.
The net effect of this is that you can set the name prefix at the beginning of a scope to some value
and then use short and simple names for the nodes inside the scope. Later, outside the scope, you
can reference the nodes via their full name:
A
B
A
B
\tikz {
\begin{scope}[name prefix = top-]
\node (A) at (0,1) {A};
\node (B) at (1,1) {B};
\draw (A) -- (B);
\end{scope}
\begin{scope}[name prefix = bottom-]
\node (A) at (0,0) {A};
\node (B) at (1,0) {B};
\draw (A) -- (B);
\end{scope}
\draw [red] (top-A) -- (bottom-B);
}
As can be seen, name prefixing makes it easy to write “recycable” code.
217
(no default, initially empty)
/tikz/name suffix=htexti
Works as name prefix, only the htexti is appended to every node name in the current scope.
There is a special syntax for specifying “light-weight” nodes:
\path . . . coordinate[hoptionsi](hnamei)at(hcoordinatei) . . . ;
This has the same effect as
\node[shape=coordinate][hoptionsi](hnamei)at(hcoordinatei){},
where the at part may be omitted.
Since nodes are often the only path operation on paths, there are two special commands for creating
paths containing only a node:
\node
Inside {tikzpicture} this is an abbreviation for \path node.
\coordinate
Inside {tikzpicture} this is an abbreviation for \path coordinate.
17.2.2
Predefined Shapes
pgf and Tik Z define three shapes, by default:
• rectangle,
• circle, and
• coordinate.
By loading library packages, you can define more shapes like ellipses or diamonds; see Section 67 for the
complete list of shapes.
The coordinate shape is handled in a special way by Tik Z. When a node x whose shape is coordinate
is used as a coordinate (x), this has the same effect as if you had said (x.center). None of the special “line
shortening rules” apply in this case. This can be useful since, normally, the line shortening causes paths to
be segmented and they cannot be used for filling. Here is an example that demonstrates the difference:
\begin{tikzpicture}[every node/.style={draw}]
\path[yshift=1.5cm,shape=rectangle]
(0,0) node(a1){} (1,0) node(a2){}
(1,1) node(a3){} (0,1) node(a4){};
\filldraw[fill=yellow!80!black] (a1) -- (a2) -- (a3) -- (a4);
\path[shape=coordinate]
(0,0) coordinate(b1) (1,0) coordinate(b2)
(1,1) coordinate(b3) (0,1) coordinate(b4);
\filldraw[fill=yellow!80!black] (b1) -- (b2) -- (b3) -- (b4);
\end{tikzpicture}
17.2.3
Common Options: Separations, Margins, Padding and Border Rotation
The exact behaviour of shapes differs, shapes defined for more special purposes (like a, say, transistor shape)
will have even more custom behaviors. However, there are some options that apply to most shapes:
(no default, initially .3333em)
/pgf/inner sep=hdimensioni
alias /tikz/inner sep
An additional (invisible) separation space of hdimensioni will be added inside the shape, between the
text and the shape’s background path. The effect is as if you had added appropriate horizontal and
vertical skips at the beginning and end of the text to make it a bit “larger.”
For those familiar with css, this is the same as padding.
default
loose
tight
\begin{tikzpicture}
\draw (0,0)
node[inner sep=0pt,draw] {tight}
(0cm,2em) node[inner sep=5pt,draw] {loose}
(0cm,4em) node[fill=yellow!80!black]
{default};
\end{tikzpicture}
218
(no default, initially .3333em)
/pgf/inner xsep=hdimensioni
alias /tikz/inner xsep
Specifies the inner separation in the x-direction, only.
(no default, initially .3333em)
/pgf/inner ysep=hdimensioni
alias /tikz/inner ysep
Specifies the inner separation in the y-direction, only.
/pgf/outer sep=hdimension or “auto” i
(no default)
alias /tikz/outer sep
This option adds an additional (invisible) separation space of hdimensioni outside the background path.
The main effect of this option is that all anchors will move a little “to the outside.”
For those familiar with css, this is same as margin.
The default for this option is half the line width. When the default is used and when the background
path is draw, the anchors will lie exactly on the “outside border” of the path (not on the path itself).
filled
drawn
scaled
\begin{tikzpicture}
\draw[line width=5pt]
(0,0) node[fill=yellow!80!black] (f) {filled}
(2,0) node[draw]
(d) {drawn}
(1,-2) node[draw,scale=2]
(s) {scaled};
\draw[->] (1,-1) -- (f);
\draw[->] (1,-1) -- (d);
\draw[->] (1,-1) -- (s);
\end{tikzpicture}
As the above example demonstrates, the standard settings for the outer sep are not always “correct.”
First, when a shape is filled, but not drawn, the outer sep should actually be 0. Second, when a node
is scaled, for instance by a factor of 5, the outer separation also gets scaled by a factor of 5, while the
line width stays at its original width; again causing problems.
In such cases, you can say outer sep=auto to make Tik Z try to compensate for the effects described
above. This is done by, firstly, setting the outer sep to 0 when no drawing is done and, secondly,
setting the outer separations to half the line width (as before) times two adjustment factors, one for
the horizontal separations and one for the vertical separations (see Section 103.2.5 for details on these
factors). Note, however, that these factors can compensate only for transformations that are either
scalings plus rotations or scalings with different magnitudes in the horizontal and the vertical direction.
If you apply slanting, the factors will only approximate the correct values.
In general, it is a good idea to say outer sep=auto at some early stage. It is not the default mainly
for compatibility with earlier versions.
filled
drawn
scaled
\begin{tikzpicture}[outer sep=auto]
\draw[line width=5pt]
(0,0) node[fill=yellow!80!black] (f) {filled}
(2,0) node[draw]
(d) {drawn}
(1,-2) node[draw,scale=2]
(s) {scaled};
\draw[->] (1,-1) -- (f);
\draw[->] (1,-1) -- (d);
\draw[->] (1,-1) -- (s);
\end{tikzpicture}
(no default, initially .5\pgflinewidth)
/pgf/outer xsep=hdimensioni
alias /tikz/outer xsep
Specifies the outer separation in the x-direction, only. This value will be overwritten when outer sep
is set, either to the value given there or a computed value in case of auto.
(no default, initially .5\pgflinewidth)
/pgf/outer ysep=hdimensioni
alias /tikz/outer ysep
Specifies the outer separation in the y-direction, only.
(no default, initially 0pt)
/pgf/minimum height=hdimensioni
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alias /tikz/minimum height
This option ensures that the height of the shape (including the inner, but ignoring the outer separation)
will be at least hdimensioni. Thus, if the text plus the inner separation is not at least as large as
hdimensioni, the shape will be enlarged appropriately. However, if the text is already larger than
hdimensioni, the shape will not be shrunk.
1cm
0cm
\begin{tikzpicture}
\draw (0,0) node[minimum height=1cm,draw] {1cm}
(2,0) node[minimum height=0cm,draw] {0cm};
\end{tikzpicture}
(no default, initially 0pt)
/pgf/minimum width=hdimensioni
alias /tikz/minimum width
Same as minimum height, only for the width.
\begin{tikzpicture}
\draw (0,0) node[minimum height=2cm,minimum width=3cm,draw] {$3 \times 2$};
\end{tikzpicture}
3×2
(no default)
/pgf/minimum size=hdimensioni
alias /tikz/minimum size
Sets both the minimum height and width at the same time.
square
\begin{tikzpicture}
\draw (0,0) node[minimum size=2cm,draw] {square};
\draw (0,-2) node[minimum size=2cm,draw,circle] {circle};
\end{tikzpicture}
circle
/pgf/shape aspect=haspect ratioi
(no default)
alias /tikz/shape aspect
Sets a desired aspect ratio for the shape. For the diamond shape, this option sets the ratio between
width and height of the shape.
\begin{tikzpicture}
\draw (0,0) node[shape aspect=1,diamond,draw] {aspect 1};
\draw (0,-2) node[shape aspect=2,diamond,draw] {aspect 2};
\end{tikzpicture}
aspect 1
aspect 2
A
B
C
D
Some shapes (but not all), support a special kind of rotation. This rotation affects only the border of a
shape and is independent of the node contents, but in addition to any other transformations.
\tikzstyle{every node}=[dart, shape border uses incircle,
inner sep=1pt, draw]
\tikz \node foreach \a/\b/\c in {A/0/0, B/45/0, C/0/45, D/45/45}
[shape border rotate=\b, rotate=\c] at (\b/36,-\c/36) {\a};
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There are two types of rotation: restricted and unrestricted. Which type of rotation is applied is determined by on how the shape border is constructed. If the shape border is constructed using an incircle,
that is, a circle that tightly fits the node contents (including the inner sep), then the rotation can be
unrestricted. If, however, the border is constructed using the natural dimensions of the node contents, the
rotation is restricted to integer multiples of 90 degrees.
Why should there be two kinds of rotation and border construction? Borders constructed using the
natural dimensions of the node contents provide a much tighter fit to the node contents, but to maintain
this tight fit, the border rotation must be restricted to integer multiples of 90 degrees. By using an incircle,
unrestricted rotation is possible, but the border will not make a very tight fit to the node contents.
abc
\tikzstyle{every node}=[isosceles triangle, draw]
\begin{tikzpicture}
\node {abc};
\node [shape border uses incircle] at (2,0) {abc};
\end{tikzpicture}
abc
There are pgf keys that determine how a shape border is constructed, and to specify its rotation. It
should be noted that not all shapes support these keys, so reference should be made to the documentation
for individual shapes.
(default true)
/pgf/shape border uses incircle=hbooleani
alias /tikz/shape border uses incircle
Determines if the border of a shape is constructed using the incircle. If no value is given hbooleani will
take the default value true.
(no default, initially 0)
/pgf/shape border rotate=hanglei
alias /tikz/shape border rotate
Rotates the border of a shape independently of the node contents, but in addition to any other transformations. If the shape border is not constructed using the incircle, the rotation will be rounded to
the nearest integer multiple of 90 degrees when the shape is drawn.
Note that if the border of the shape is rotated, the compass point anchors, and ‘text box’ anchors
(including mid east, base west, and so on), do not rotate, but the other anchors do:
A
B
\tikzstyle{every node}=[shape=trapezium, draw, shape border uses incircle]
\begin{tikzpicture}
\node at (0,0) (A) {A};
\node [shape border rotate=30] at (1.5,0) (B) {B};
\foreach \s/\t in
{left side/base east, bottom side/north, bottom left corner/base}{
\fill[red] (A.\s) circle(1.5pt) (B.\s) circle(1.5pt);
\fill[blue] (A.\t) circle(1.5pt) (B.\t) circle(1.5pt);
}
\end{tikzpicture}
Finally, a somewhat unfortunate side-effect of rotating shape borders is that the supporting shapes do
not distinguish between outer xsep and outer ysep, and typically, the larger of the two values will be
used.
17.3
Multi-Part Nodes
Most nodes just have a single simple text label. However, nodes of a more complicated shape might be made
up from several node parts. For example, in automata theory a so-called Moore state has a state name,
drawn in the upper part of the state circle, and an output text, drawn in the lower part of the state circle.
These two parts are quite independent. Similarly, a uml class shape would have a name part, a method
part, and an attributes part. Different molecule shapes might use parts for the different atoms to be drawn
at the different positions, and so on.
Both pgf and Tik Z support such multipart nodes. On the lower level, pgf provides a system for
specifying that a shape consists of several parts. On the Tik Z level, you specify the different node parts by
using the following command:
\nodepart[hoptionsi]{hpart namei}
This command can only be used inside the htexti argument of a node path operation. It works a little
bit like a \part command in LATEX. It will stop the typesetting of whatever node part was typeset until
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now and then start putting all following text into the node part named hpart namei—until another
\partname is encountered or until the node htexti ends. The hoptionsi will be local to this part.
q1
00
\begin{tikzpicture}
\node [circle split,draw,double,fill=red!20]
{
% No \nodepart has been used, yet. So, the following is put in the
% ‘‘text’’ node part by default.
$q_1$
\nodepart{lower} % Ok, end ‘‘text’’ part, start ‘‘output’’ part
$00$
}; % output part ended.
\end{tikzpicture}
You will have to lookup which parts are defined by a shape.
The following styles influences node parts:
/tikz/every hpart name i node part
(style, initially empty)
This style is installed at the beginning of every node part named hpart namei.
q1
\tikz [every lower node part/.style={red}]
\node [circle split,draw] {$q_1$ \nodepart{lower} $00$};
00
17.4
17.4.1
The Node Text
Text Parameters: Color and Opacity
The simplest option for the text in nodes is its color. Normally, this color is just the last color installed using
color=, possibly inherited from another scope. However, it is possible to specifically set the color used for
text using the following option:
/tikz/text=hcolor i
(no default)
Sets the color to be used for text labels. A color= option will immediately override this option.
red
red
red
\begin{tikzpicture}
\draw[red]
(0,0) -- +(1,1) node[above]
{red};
\draw[text=red] (1,0) -- +(1,1) node[above]
{red};
\draw
(2,0) -- +(1,1) node[above,red] {red};
\end{tikzpicture}
Just like the color itself, you may also wish to set the opacity of the text only. For this, use the
text opacity option, which is detailed in Section 23.
17.4.2
Text Parameters: Font
Next, you may wish to adjust the font used for the text. Naturally, you can just use a font command like
\small or \rm at the beginning of a node. However, the following two options make it easier to set the font
used in nodes on a general basis. Let us start with:
/tikz/node font=hfont commandsi
(no default)
This option sets the font used for all text used in a node.
italic
\begin{tikzpicture}
\draw[node font=\itshape] (1,0) -- +(1,1) node[above] {italic};
\end{tikzpicture}
Since the hfont commandsi are executed at a very early stage in the construction of the node, the font
selected using this command will also dictate the values of dimensions defined in terms of em or ex. For
instance, when the minimum height of a node is 3em, the actual height will be (at least) three times
the line distance selected by the hfont commandsi:
222
tiny
small
\tikz \node [node font=\tiny, minimum height=3em, draw] {tiny};
\tikz \node [node font=\small, minimum height=3em, draw] {small};
The other font command is:
/tikz/font=hfont commandsi
(no default)
Sets the font used for the text inside nodes. However, this font will not (yet) be installed when any of
the dimensions of the node are being computed, so dimensions like 1em will be with respect to the font
used outside the node (usually the font that was in force when the picture started).
italic
tiny
small
\begin{tikzpicture}
\node [font=\itshape] {italic};
\end{tikzpicture}
\tikz \node [font=\tiny, minimum height=3em, draw] {tiny};
\tikz \node [font=\small, minimum height=3em, draw] {small};
A useful example of how the font option can be used is the following:
state
output
\tikz [every text node part/.style={font=\itshape},
every lower node part/.style={font=\footnotesize}]
\node [circle split,draw] {state \nodepart{lower} output};
As can be seen, the font can be changed for each node part. This does not work with the node font
command since, as the name suggests, this command can only be used to select the “overall” font for
the node and this is done very early.
17.4.3
Text Parameters: Alignment and Width for Multi-Line Text
Normally, when a node is typeset, all the text you give in the braces is put in one long line (in an \hbox, to
be precise) and the node will become as wide as necessary.
From time to time you may wish to create nodes that contain multiple lines of text. There are three
different ways of achieving this:
1. Inside the node, you can put some standard environment that produces multi-line, aligned text. For
instance, you can use a {tabular} inside a node:
upper left
lower left
upper right
lower right
\tikz \node [draw] {
\begin{tabular}{cc}
upper left & upper right\\
lower left & lower right
\end{tabular}
};
This approach offers the most flexibility in the sense that it allows you to use all of the alignment
commands offered by your format of choice.
2. You use \\ inside your node to mark the end of lines and then request Tik Z to arrange these lines in
some manner. This will only be done, however, if the align option has been given.
This is a
demonstration.
\tikz[align=left] \node[draw] {This is a\\demonstration.};
This is a
demonstration.
\tikz[align=center] \node[draw] {This is a\\demonstration.};
The \\ command takes an optional extra space as an argument in square brackets.
223
This is a
demonstration text for
\tikz \node[fill=yellow!80!black,align=right]
{This is a\\[-2pt] demonstration text for\\[1ex] alignments.};
alignments.
3. You can request that Tik Z does an automatic line-breaking for you inside the node by specifying a fixed
text width for the node. In this case, you can still use \\ to enforce a line-break. Note that when
you specify a text width, the node will have this width, independently of whether the text actually
“reaches the end” of the node.
Let us now first have a look at the text width command.
(no default)
/tikz/text width=hdimensioni
This option will put the text of a node in a box of the given width (something akin to a {minipage}
of this width, only portable across formats). If the node text is not as wide as hdimensioni, it will
nevertheless be put in a box of this width. If it is larger, line breaking will be done.
By default, when this option is given, a ragged right border will be used (align=left). This is sensible
since, typically, these boxes are narrow and justifying the text looks ugly. You can, however, change the
alignment using align or directly using commands line \centering.
This is a demonstration text for
showing how line
breaking works.
\tikz \draw (0,0) node[fill=yellow!80!black,text width=3cm]
{This is a demonstration text for showing how line breaking works.};
Setting hdimensioni to an empty string causes the automatic line breaking to be disabled.
/tikz/align=halignment optioni
(no default)
This key is used to set up an alignment for multi-line text inside a node. If text width is set to some
width (let us call this alignment with line breaking), the align key will setup the \leftskip and the
\rightskip in such a way that the text is broken and aligned according to halignment optioni. If
text width is not set (that is, set to the empty string; let us call this alignment without line breaking), then a different mechanism is used internally, namely the key node halign header, is set to an
appropriate value. While this key, which is documented below, is not to be used by beginners, the net
effect is simple: When text width is not set, you can use \\ to break lines and align them according
to halignment optioni and the resulting node’s width will be minimal to encompass the resulting lines.
In detail, you can set halignment optioni to one of the following values:
align=left For alignment without line breaking, the different lines are simply aligned such that their
left borders are below one another.
This is a
demonstration text for
alignments.
\tikz \node[fill=yellow!80!black,align=left]
{This is a\\ demonstration text for\\ alignments.};
For alignment with line breaking, the same will happen only the lines will now, additionally, be
broken automatically:
This is a demonstration text for
showing how line
breaking works.
\tikz \node[fill=yellow!80!black,text width=3cm,align=left]
{This is a demonstration text for showing how line breaking works.};
align=flush left For alignment without line breaking this option has exactly the same effect as left.
However, for alignment with line breaking, there is a difference: While left uses the original plain
TEX definition of a ragged right border, in which TEX will try to balance the right border as well as
possible, flush left causes the right border to be ragged in the LATEX-style, in which no balancing
224
occurs. This looks ugly, but it may be useful for very narrow boxes and when you wish to avoid
hyphenations.
This is a
demonstration text
for showing how
line breaking
works.
\tikz \node[fill=yellow!80!black,text width=3cm,align=flush left]
{This is a demonstration text for showing how line breaking works.};
align=right Works like left, only for right alignment.
This is a
demonstration text for
alignments.
This is a demonstration text for
showing how line
breaking works.
\tikz \node[fill=yellow!80!black,align=right]
{This is a\\ demonstration text for\\ alignments.};
\tikz \node[fill=yellow!80!black,text width=3cm,align=right]
{This is a demonstration text for showing how line breaking works.};
align=flush right Works like flush left, only for right alignment.
This is a
demonstration text
for showing how
line breaking
works.
\tikz \node[fill=yellow!80!black,text width=3cm,align=flush right]
{This is a demonstration text for showing how line breaking works.};
align=center Works like left or right, only for centered alignment.
This is a
demonstration text for
alignments.
This is a demonstration text for
showing how line
breaking works.
\tikz \node[fill=yellow!80!black,align=center]
{This is a\\ demonstration text for\\ alignments.};
\tikz \node[fill=yellow!80!black,text width=3cm,align=center]
{This is a demonstration text for showing how line breaking works.};
There is one annoying problem with the center alignment (but not with flush center and the
other options): If you specify a large line width and the node text fits on a single line and is, in fact,
much shorter than the specified text width, an underfull horizontal box will result. Unfortunately,
this cannot be avoided, due to the way TEX works (more precisely, I have thought long and hard
about this and have not been able to figure out a sensible way to avoid this). For this reason,
Tik Z switches off horizontal badness warnings inside boxes with align=center. Since this will
also suppress some “wanted” warnings, there is also an option for switching the warnings on once
more:
/tikz/badness warnings for centered text=htrue or falsei
(no default, initially false)
If set to true, normal badness warnings will be issued for centered boxes. Note that you may
get annoying warnings for perfectly normal boxes, namely whenever the box is very large and
the contents is not long enough to fill the box sufficiently.
align=flush center Works like flush left or flush right, only for center alignment. Because of
all the trouble that results from the center option in conjunction with narrow lines, I suggest
225
picking this option rather than center unless you have longer text, in which case center will give
the typographically better results.
This is a
demonstration text
for showing how
line breaking
works.
\tikz \node[fill=yellow!80!black,text width=3cm,align=flush center]
{This is a demonstration text for showing how line breaking works.};
align=justify For alignment without line breaking, this has the same effect as left. For alignment
with line breaking, this causes the text to be “justified.” Use this only with rather broad nodes.
This is
stration
showing
breaking
a demontext for
how line
works.
\tikz \node[fill=yellow!80!black,text width=3cm,align=justify]
{This is a demonstration text for showing how line breaking works.};
In the above example, TEX complains (rightfully) about three very badly typeset lines. (For this
manual I asked TEX to stop complaining by using \hbadness=10000, but this is a foul deed,
indeed.)
align=none Disables all alignments and \\ will not be redefined.
/tikz/node halign header=hmacro storing a header i
(no default, initially empty)
This is the key that is used by align internally for alignment without line breaking. Read the following
only if you are familiar with the \halign command.
This key only has an effect if text width is empty, otherwise it is ignored. Furthermore, if hmacro
storing a header i is empty, then this key also has no effect. So, suppose text width is empty, but
hheader i is not. In this case the following happens:
When the node text is parsed, the command \\ is redefined internally. This redefinition is done in such
a way that the text from the start of the node to the first occurrence of \\ is put in an \hbox. Then
the text following \\ up to the next \\ is put in another \hbox. This goes on until the text between
the last \\ and the closing } is also put in an \hbox.
The hmacro storing a header i should be a macro that contains some text suitable for use as a header
for the \halign command. For instance, you might define
\def\myheader{\hfil\hfil##\hfil\cr}
\tikz [node halign header=\myheader] ...
You cannot just say node halign header=\hfil\hfil#\hfil\cr because this confuses TEX inside
matrices, so this detour via a macro is needed.
Next, conceptually, all these boxes are recursively put inside an \halign command. Assuming that
hfirsti is the first of the above boxes, the command \halign{hheader i \boxhfirsti \cr} is used to create
a new box, which we will call the hprevious box i. Then, the following box is created, where hsecond i
is the second input box: \halign{hheader i \boxhprevious box i \cr \boxhsecond i\cr}. Let us call the
resulting box the hprevious box i once more. Then the next box that is created is \halign{hheader i
\boxhprevious box i \cr \boxhthird i\cr}.
All of this means that if hheader i is an \halign header like \hfil#\hfil\cr, then all boxes will be
centered relative to one another. Similarly, a hheader i of \hfil#\cr causes the text to be flushed right.
Note that this mechanism is not flexible enough to all multiple columns inside hheader i. You will have
to use a tabular or a matrix in such cases.
One further note: Since the text of each line is placed in a box, settings will be local to each “line.” This
is very similar to the way a cell in a tabular or a matrix behaves.
17.4.4
Text Parameters: Height and Depth of Text
In addition to changing the width of nodes, you can also change the height of nodes. This can be done in
two ways: First, you can use the option minimum height, which ensures that the height of the whole node
226
is at least the given height (this option is described in more detail later). Second, you can use the option
text height, which sets the height of the text itself, more precisely, of the TEX text box of the text. Note
that the text height typically is not the height of the shape’s box: In addition to the text height, an
internal inner sep is added as extra space and the text depth is also taken into account.
I recommend using minimum size instead of text height except for special situations.
(no default)
/tikz/text height=hdimensioni
Sets the height of the text boxes in shapes. Thus, when you write something like node {text}, the
text is first typeset, resulting in some box of a certain height. This height is then replaced by the height
text height. The resulting box is then used to determine the size of the shape, which will typically be
larger. When you write text height= without specifying anything, the “natural” size of the text box
remains unchanged.
y y
\tikz \node[draw]
{y};
\tikz \node[draw,text height=10pt] {y};
(no default)
/tikz/text depth=hdimensioni
This option works like text height, only for the depth of the text box. This option is mostly useful
when you need to ensure a uniform depth of text boxes that need to be aligned.
17.5
Positioning Nodes
When you place a node at some coordinate, the node is centered on this coordinate by default. This is often
undesirable and it would be better to have the node to the right or above the actual coordinate.
17.5.1
Positioning Nodes Using Anchors
pgf uses a so-called anchoring mechanism to give you a very fine control over the placement. The idea is
simple: Imagine a node of rectangular shape of a certain size. pgf defines numerous anchor positions in
the shape. For example to upper right corner is called, well, not “upper right anchor,” but the north east
anchor of the shape. The center of the shape has an anchor called center on top of it, and so on. Here are
some examples (a complete list is given in Section 17.2.2).
north west
west
north
Big node
base
north east
east
Now, when you place a node at a certain coordinate, you can ask Tik Z to place the node shifted around
in such a way that a certain anchor is at the coordinate. In the following example, we ask Tik Z to shift the
first node such that its north east anchor is at coordinate (0,0) and that the west anchor of the second
node is at coordinate (1,1).
second node
first node
\tikz \draw
(0,0) node[anchor=north east] {first node}
rectangle (1,1) node[anchor=west] {second node};
Since the default anchor is center, the default behaviour is to shift the node in such a way that it is
centered on the current position.
/tikz/anchor=hanchor namei
(no default)
Causes the node to be shifted such that it’s anchor hanchor namei lies on the current coordinate.
The only anchor that is present in all shapes is center. However, most shapes will at least define
anchors in all “compass directions.” Furthermore, the standard shapes also define a base anchor, as well
as base west and base east, for placing things on the baseline of the text.
227
The standard shapes also define a mid anchor (and mid west and mid east). This anchor is half the
height of the character “x” above the base line. This anchor is useful for vertically centering multiple
nodes that have different heights and depth. Here is an example:
x y t
x y t
x y t
\begin{tikzpicture}[scale=3,transform shape]
% First, center alignment -> wobbles
\draw[anchor=center] (0,1) node{x} -- (0.5,1) node{y} -- (1,1) node{t};
% Second, base alignment -> no wobble, but too high
\draw[anchor=base]
(0,.5) node{x} -- (0.5,.5) node{y} -- (1,.5) node{t};
% Third, mid alignment
\draw[anchor=mid]
(0,0) node{x} -- (0.5,0) node{y} -- (1,0) node{t};
\end{tikzpicture}
17.5.2
Basic Placement Options
Unfortunately, while perfectly logical, it is often rather counter-intuitive that in order to place a node above
a given point, you need to specify the south anchor. For this reason, there are some useful options that
allow you to select the standard anchors more intuitively:
(default 0pt)
/tikz/above=hoffseti
Does the same as anchor=south. If the hoffseti is specified, the node is additionally shifted upwards by
the given hoffseti.
above
\tikz \fill (0,0) circle (2pt) node[above] {above};
above
\tikz \fill (0,0) circle (2pt) node[above=2pt] {above};
(default 0pt)
/tikz/below=hoffseti
Similar to above.
(default 0pt)
/tikz/left=hoffseti
Similar to above.
(default 0pt)
/tikz/right=hoffseti
Similar to above.
(no value)
/tikz/above left
Does the same as anchor=south east. Note that giving both above and left options does not have
the same effect as above left, rather only the last left “wins.” Actually, this option also takes an
hoffseti parameter, but using this parameter without using the positioning library is deprecated. (The
positioning library changes the meaning of this parameter to something more sensible.)
above left
\tikz \fill (0,0) circle (2pt) node[above left] {above left};
228
(no value)
/tikz/above right
Similar to above left.
above right
\tikz \fill (0,0) circle (2pt) node[above right] {above right};
(no value)
/tikz/below left
Similar to above left.
(no value)
/tikz/below right
Similar to above left.
(no value)
/tikz/centered
A shorthand for anchor=center.
17.5.3
Advanced Placement Options
While the standard placement options suffice for simple cases, the positioning library offers more convenient
placement options.
Tik Z Library positioning
\usetikzlibrary{positioning} % LATEX and plain TEX
\usetikzlibrary[positioning] % ConTEXt
The library defines additional options for placing nodes conveniently. It also redefines the standard
options like above so that they give you better control of node placement.
When this library is loaded, the options like above or above left behave differently.
(default 0pt)
/tikz/above=hspecificationi
With the positioning library loaded, the above option does not take a simple hdimensioni as its
parameter. Rather, it can (also) take a more elaborate hspecificationi as parameter. This hspecificationi
has the following general form: It starts with an optional hshifting parti and is followed by an optional
hof-parti. Let us start with the hshifting parti, which can have three forms:
1. It can simply be a hdimensioni (or a mathematical expression that evaluates to a dimension) like
2cm or 3cm/2+4cm. In this case, the following happens: the node’s anchor is set to south and the
node is vertically shifted upwards by hdimensioni.
above
\begin{tikzpicture}
\draw[help lines] (0,0) grid (2,2);
\node at (1,1) [above=2pt+3pt,draw] {above};
\end{tikzpicture}
This use of the above option is the same as if the positioning library were not loaded.
2. It can be a hnumber i (that is, any mathematical expression that does not include a unit like pt or
cm). Examples are 2 or 3+sin(60). In this case, the anchor is also set to south and the node is
vertically shifted by the vertical component of the coordinate (0,hnumber i).
above
\begin{tikzpicture}
\draw[help lines] (0,0) grid (2,2);
\node at (1,1) [above=.2,draw] {above};
% south border of the node is now 2mm above (1,1)
\end{tikzpicture}
229
3. It can be of the form hnumber or dimension 1 i and hnumber or dimension 2 i. This specification does not make particular sense for the above option, it is much more useful for options like
above left. The reason it is allowed for the above option is that it is sometimes automatically
used, as explained later.
The effect of this option is the following. First, the point (hnumber or dimension 2 i,hnumber or
dimension 1 i) is computed (note the inversed order), using the normal rules for evaluating such
a coordinate, yielding some position. Then, the node is shifted by the vertical component of this
point. The anchor is set to south.
above
\begin{tikzpicture}
\draw[help lines] (0,0) grid (2,2);
\node at (1,1) [above=.2 and 3mm,draw] {above};
% south border of the node is also 2mm above (1,1)
\end{tikzpicture}
The hshifting parti can optionally be followed by a hof-parti, which has one of the following forms:
1. The hof-parti can be of hcoordinatei, where hcoordinatei is not in parentheses and it is not just
a node name. An example would be of somenode.north or of 2,3. In this case, the following
happens: First, the node’s at parameter is set to the hcoordinatei. Second, the node is shifted
according to the hshift-parti. Third, the anchor is set to south.
Here is a basic example:
1cm of somenode.north
5mm of somenode.north east
\begin{tikzpicture}[every node/.style=draw]
\draw[help lines] (0,0) grid (2,2);
\node (somenode) at (1,1) {some node};
\node [above=5mm of somenode.north east] {\tiny 5mm of somenode.north east};
\node [above=1cm of somenode.north]
{\tiny 1cm of somenode.north};
\end{tikzpicture}
some node
As can be seen the above=5mm of somenode.north east option does, indeed, place the node
5mm above the north east anchor of somenode. The same effect could have been achieved writing
above=5mm followed by at=(somenode.north east).
If the hshifting-parti is missing, the shift is not zero, but rather the value of the node distance
key is used, see below.
2. The hof-parti can be of hnode namei. An example would be of somenode. In this case, the
following usually happens:
• The anchor is set to south.
• The node is shifted according to the hshifting parti or, if it is missing, according to the value
of node distance.
• The node’s at parameter is set to hnode namei.north.
The net effect of all this is that the new node will be placed in such a way that the distance between
is south border and hnode namei’s north border is exactly the given distance.
above=1cm of some node
1cm
some node
\begin{tikzpicture}[every node/.style=draw]
\draw[help lines] (0,0) grid (2,2);
\node (some node) at (1,1) {some node};
\node (other node) [above=1cm of some node] {\tiny above=1cm of some node};
\draw [<->] (some node.north) -- (other node.south)
node [midway,right,draw=none] {1cm};
\end{tikzpicture}
It is possible to change the behaviour of this hspecificationi rather drastically, using the following
key:
(no default, initially false)
/tikz/on grid=hbooleani
When this key is set to true, an hof-parti of the current form behaves differently: The anchors
set for the current node as well as the anchor used for the other hnode namei are set to center.
230
This has the following effect: When you say above=1cm of somenode with on grid set to
true, the new node will be placed in such a way that its center is 1cm above the center of
somenode. Repeatedly placing nodes in this way will result in nodes that are centered on “grid
coordinate,” hence the name of the option.
\begin{tikzpicture}[every node/.style=draw]
\draw[help lines] (0,0) grid (2,3);
a
a
fooy
fooy
not gridded
gridded
% Not
\node
\node
\node
gridded
(a1) at (0,0) {not gridded};
(b1) [above=1cm of a1] {fooy};
(c1) [above=1cm of b1] {a};
% gridded
\node (a2) at (2,0) {gridded};
\node (b2) [on grid,above=1cm of a2] {fooy};
\node (c2) [on grid,above=1cm of b2] {a};
\end{tikzpicture}
/tikz/node distance=hshifting parti
(no default, initially 1cm and 1cm)
The value of this key is used as hshifting parti is used if and only if a hof-parti is present, but no
hshifting parti.
\begin{tikzpicture}[every node/.style=draw,node distance=5mm]
\draw[help lines] (0,0) grid (2,3);
a
fooy
not gridded
a
fooy
gridded
% Not
\node
\node
\node
gridded
(a1) at (0,0) {not gridded};
(b1) [above=of a1] {fooy};
(c1) [above=of b1] {a};
% gridded
\begin{scope}[on grid]
\node (a2) at (2,0) {gridded};
\node (b2) [above=of a2] {fooy};
\node (c2) [above=of b2] {a};
\end{scope}
\end{tikzpicture}
(no default)
/tikz/below=hspecificationi
This key is redefined in the same manner as above.
(no default)
/tikz/left=hspecificationi
This key is redefined in the same manner as above, only all vertical shifts are replaced by horizontal
shifts.
/tikz/right=hspecificationi
This key is redefined in the same manner as left.
(no default)
/tikz/above left=hspecificationi
(no default)
This key is also redefined in a manner similar to the above, but behaviour of the hshifting parti is more
complicated:
1. When the hshifting parti is of the form hnumber or dimensioni and hnumber or dimensioni, it has
(essentially) the effect of shifting the node vertically upwards by the first hnumber or dimensioni and
to the left by the second. To be more precise, the coordinate (hsecond number or dimensioni,hfirst
number or dimensioni) is computed and then the node is shifted vertically by the y-part of the
resulting coordinate and horizontally be the negated x-part of the result. (This is exactly what
you expect, except possibly when you have used the x and y options to modify the xy-coordinate
system so that the unit vectors no longer point in the expected directions.)
2. When the hshifting parti is of the form hnumber or dimensioni, the node is shifted by this hnumber
or dimensioni in the direction of 135◦ . This means that there is a difference between a hshifting
parti of 1cm and of 1cm and 1cm: In the second case, the node is shifted by 1cm upward and 1cm
231
√
to the left; in the first case it is shifted by 12 2cm upward and by the same amount to the left. A
more mathematical way of phrasing this is the following: A plain hdimensioni is measured in the
l2 -norm, while a hdimensioni and hdimensioni is measured in the l1 -norm.
The following example should help to illustrate the difference:
3
5
1
6
2
b
7
8
4
3
5
6
a
1
2
7
8
4
5
3
6
1
b
2
7
4
8
5
1
7
5
3
3
a
4
6
a
1
7
4
2
8
5
3
6
1
b
2
7
4
8
6
2
8
\begin{tikzpicture}[every node/.style={draw,circle}]
\draw[help lines] (0,0) grid (2,5);
\begin{scope}[node distance=5mm and 5mm]
\node (b) at (1,4) {b};
\node [left=of b] {1};
\node [right=of b] {2};
\node [above=of b] {3};
\node [below=of b] {4};
\node [above left=of b] {5}; \node [above right=of b]
\node [below left=of b] {7}; \node [below right=of b]
\end{scope}
\begin{scope}[node distance=5mm]
\node (a) at (1,1) {a};
\node [left=of a] {1};
\node [right=of a] {2};
\node [above=of a] {3};
\node [below=of a] {4};
\node [above left=of a] {5}; \node [above right=of a]
\node [below left=of a] {7}; \node [below right=of a]
\end{scope}
\end{tikzpicture}
\begin{tikzpicture}[every node/.style={draw,rectangle}]
\draw[help lines] (0,0) grid (2,5);
\begin{scope}[node distance=5mm and 5mm]
\node (b) at (1,4) {b};
\node [left=of b] {1};
\node [right=of b] {2};
\node [above=of b] {3};
\node [below=of b] {4};
\node [above left=of b] {5}; \node [above right=of b]
\node [below left=of b] {7}; \node [below right=of b]
\end{scope}
\begin{scope}[node distance=5mm]
\node (a) at (1,1) {a};
\node [left=of a] {1};
\node [right=of a] {2};
\node [above=of a] {3};
\node [below=of a] {4};
\node [above left=of a] {5}; \node [above right=of a]
\node [below left=of a] {7}; \node [below right=of a]
\end{scope}
\end{tikzpicture}
\begin{tikzpicture}[every node/.style={draw,rectangle},on
\draw[help lines] (0,0) grid (4,4);
\begin{scope}[node distance=1]
\node (a) at (2,3) {a};
\node [left=of a] {1};
\node [right=of a] {2};
\node [above=of a] {3};
\node [below=of a] {4};
\node [above left=of a] {5}; \node [above right=of a]
\node [below left=of a] {7}; \node [below right=of a]
\end{scope}
\begin{scope}[node distance=1 and 1]
\node (b) at (2,0) {b};
\node [left=of b] {1};
\node [right=of b] {2};
\node [above=of b] {3};
\node [below=of b] {4};
\node [above left=of b] {5}; \node [above right=of b]
\node [below left=of b] {7}; \node [below right=of b]
\end{scope}
\end{tikzpicture}
{6};
{8};
{6};
{8};
{6};
{8};
{6};
{8};
grid]
{6};
{8};
{6};
{8};
(no default)
/tikz/below left=hspecificationi
Works similar to above left.
(no default)
/tikz/above right=hspecificationi
Works similar to above left.
(no default)
/tikz/below right=hspecificationi
Works similar to above left.
232
The positioning package also introduces the following new placement keys:
(no default)
/tikz/base left=hspecificationi
This key works like the left key, only instead of the east anchor, the base east anchor is used and,
when the second form of an hof-parti is used, the corresponding base west anchor.
This key is useful for chaining together nodes so that their base lines are aligned.
X
X
a
y
a
y
\begin{tikzpicture}[node distance=1ex]
\draw[help lines] (0,0) grid (3,1);
\huge
\node (X) at (0,1)
{X};
\node (a) [right=of X] {a};
\node (y) [right=of a] {y};
\node (X) at (0,0)
{X};
\node (a) [base right=of X] {a};
\node (y) [base right=of a] {y};
\end{tikzpicture}
(no default)
/tikz/base right=hspecificationi
Works like base left.
(no default)
/tikz/mid left=hspecificationi
Works like base left, but with mid east and mid west anchors instead of base east and base west.
(no default)
/tikz/mid right=hspecificationi
Works like mid left.
17.5.4
Advanced Arrangements of Nodes
The simple above and right options may not always suffice for arranging a large number of nodes. For
such situations Tik Z offers libraries that make positioning easier: The graphdrawing library and the matrix
library. These libraries for positioning nodes are described in two separate Sections 20 and 26.
17.6
Fitting Nodes to a Set of Coordinates
It is sometimes desirable that the size and position of a node is not given using anchors and size parameters,
rather one would sometimes have a box be placed and be sized such that it “is just large enough to contain
this, that, and that point.” This situation typically arises when a picture has been drawn and, afterwards,
parts of the picture are supposed to be encircled or highlighted.
In this situation the fit option from the fit library is useful, see Section 52 for the details. The idea is
that you may give the fit option to a node. The fit option expects a list of coordinates (one after the other
without commas) as its parameter. The effect will be that the node’s text area has exactly the necessary
size so that it contains all the given coordinates. Here is an example:
root
a
c
b
d
e
\begin{tikzpicture}[level distance=8mm]
\node (root) {root}
child { node (a) {a} }
child { node (b) {b}
child { node (d) {d} }
child { node (e) {e} } }
child { node (c) {c} };
\node[draw=red,inner sep=0pt,thick,ellipse,fit=(root) (b) (d) (e)] {};
\node[draw=blue,inner sep=0pt,thick,ellipse,fit=(b) (c) (e)] {};
\end{tikzpicture}
If you want to fill the fitted node you will usually have to place it on a background layer.
233
root
a
c
b
e
d
\begin{tikzpicture}[level distance=8mm]
\node (root) {root}
child { node (a) {a} }
child { node (b) {b}
child { node (d) {d} }
child { node (e) {e} } }
child { node (c) {c} };
\begin{scope}[on background layer]
\node[fill=red!20,inner sep=0pt,ellipse,fit=(root) (b) (d) (e)] {};
\node[fill=blue!20,inner sep=0pt,ellipse,fit=(b) (c) (e)] {};
\end{scope}
\end{tikzpicture}
17.7
Transformations
It is possible to transform nodes, but, by default, transformations do not apply to nodes. The reason is that
you usually do not want your text to be scaled or rotated even if the main graphic is transformed. Scaling
text is evil, rotating slightly less so.
However, sometimes you do wish to transform a node, for example, it certainly sometimes makes sense
to rotate a node by 90 degrees. There are two ways to achieve this:
1. You can use the following option:
(no value)
/tikz/transform shape
Causes the current “external” transformation matrix to be applied to the shape. For example, if
you said \tikz[scale=3] and then say node[transform shape] {X}, you will get a “huge” X in
your graphic.
2. You can give transformation options inside the option list of the node. These transformations always
apply to the node.
\begin{tikzpicture}[every node/.style={draw}]
\draw[help lines](0,0) grid (3,2);
\draw
(1,0) node{A}
(2,0) node[rotate=90,scale=1.5] {B};
\draw[rotate=30] (1,0) node{A}
(2,0) node[rotate=90,scale=1.5] {B};
\draw[rotate=60] (1,0) node[transform shape] {A}
(2,0) node[transform shape,rotate=90,scale=1.5] {B};
\end{tikzpicture}
A
B
B
B
A
A
Even though Tik Z currently does not allow you to configure so-called nonlinear transformations, see
Section 103.4, there is an option that influences how nodes are transformed when nonlinear transformations
are in force:
/tikz/transform shape nonlinear=htrue or falsei
(no default, initially false)
When set to true, Tik Z will try to apply any current nonlinear transformation also to nodes. Typically,
for the text in nodes this is not possible in general, in such cases a linear approximation of the nonlinear
transformation is used. For more details, see Section 103.4.
0
20
40
60 80
020
40
60
\begin{tikzpicture}
% Install a nonlinear transformation:
\pgfsetcurvilinearbeziercurve
{\pgfpoint{0mm}{20mm}}
{\pgfpoint{10mm}{20mm}}
{\pgfpoint{10mm}{10mm}}
{\pgfpoint{20mm}{10mm}}
\pgftransformnonlinear{\pgfpointcurvilinearbezierorthogonal\pgf@x\pgf@y}%
80
% Draw something:
\draw [help lines] (0,-30pt) grid [step=10pt] (80pt,30pt);
\foreach \x in {0,20,...,80}
\node [fill=red!20] at (\x pt, -20pt) {\x};
\foreach \x in {0,20,...,80}
\node [fill=blue!20, transform shape nonlinear] at (\x pt, 20pt) {\x};
\end{tikzpicture}
234
17.8
Placing Nodes on a Line or Curve Explicitly
Until now, we always placed node on a coordinate that is mentioned in the path. Often, however, we wish
to place nodes on “the middle” of a line and we do not wish to compute these coordinates “by hand.” To
facilitate such placements, Tik Z allows you to specify that a certain node should be somewhere “on” a line.
There are two ways of specifying this: Either explicitly by using the pos option or implicitly by placing the
node “inside” a path operation. These two ways are described in the following.
(no default)
/tikz/pos=hfractioni
When this option is given, the node is not anchored on the last coordinate. Rather, it is anchored on
some point on the line from the previous coordinate to the current point. The hfractioni dictates how
“far” on the line the point should be. A hfractioni of 0 is the previous coordinate, 1 is the current one,
everything else is in between. In particular, 0.5 is the middle.
Now, what is “the previous line”? This depends on the previous path construction operation.
In the simplest case, the previous path operation was a “line-to” operation, that is, a --hcoordinatei
operation:
9/10
1/2
\tikz \draw (0,0) -- (3,1)
node[pos=0]{0} node[pos=0.5]{1/2} node[pos=0.9]{9/10};
0
For the arc operation, the position is simply the corresponding position on the arc:
\tikz {
\draw [help lines] (0,0) grid (3,2);
\draw (2,0) arc [x radius=1, y radius=2, start angle=0, end angle=180]
node foreach \t in {0,0.125,...,1} [pos=\t,auto] {\t};
}
0.5
0.375
0.625
0.750.25
0.8750.125
1
0
The next case is the curve-to operation (the .. operation). In this case, the “middle” of the curve, that
is, the position 0.5 is not necessarily the point at the exact half distance on the line. Rather, it is some
point at “time” 0.5 of a point traveling from the start of the curve, where it is at time 0, to the end of
the curve, which it reaches at time 0.5. The “speed” of the point depends on the length of the support
vectors (the vectors that connect the start and end points to the control points). The exact math is a
bit complicated (depending on your point of view, of course); you may wish to consult a good book on
computer graphics and Bézier curves if you are intrigued.
1
0.875
0.75
0.625
\tikz \draw (0,0) .. controls +(right:3.5cm) and +(right:3.5cm) .. (0,3)
node foreach \p in {0,0.125,...,1} [pos=\p]{\p};
0.5
0.375
0.25
0.125
0
Another interesting case are the horizontal/vertical line-to operations |- and -|. For them, the position
(or time) 0.5 is exactly the corner point.
1/2
9/10
\tikz \draw (0,0) |- (3,1)
node[pos=0]{0} node[pos=0.5]{1/2} node[pos=0.9]{9/10};
0
9/10
0
\tikz \draw (0,0) -| (3,1)
node[pos=0]{0} node[pos=0.5]{1/2} node[pos=0.9]{9/10};
1/2
235
For all other path construction operations, the position placement does not work, currently.
(default is scope’s setting)
/tikz/auto=hdirectioni
This option causes an anchor positions to be calculated automatically according to the following rule.
Consider a line between to points. If the hdirectioni is left, then the anchor is chosen such that the
node is to the left of this line. If the hdirectioni is right, then the node is to the right of this line.
Leaving out hdirectioni causes automatic placement to be enabled with the last value of left or right
used. A hdirectioni of false disables automatic placement. This happens also whenever an anchor is
given explicitly by the anchor option or by one of the above, below, etc. options.
This option only has an effect for nodes that are placed on lines or curves.
e
f
e–f
f–g
g
d–e
g–h
h
d
c–d
h–a
b–c
a–b
a
c
\begin{tikzpicture}
[scale=.8,auto=left,every node/.style={circle,fill=blue!20}]
\node (a) at (-1,-2) {a};
\node (b) at ( 1,-2) {b};
\node (c) at ( 2,-1) {c};
\node (d) at ( 2, 1) {d};
\node (e) at ( 1, 2) {e};
\node (f) at (-1, 2) {f};
\node (g) at (-2, 1) {g};
\node (h) at (-2,-1) {h};
b
\foreach \from/\to in {a/b,b/c,c/d,d/e,e/f,f/g,g/h,h/a}
\draw [->] (\from) -- (\to)
node[midway,fill=red!20] {\from--\to};
\end{tikzpicture}
(no value)
/tikz/swap
This option exchanges the roles of left and right in automatic placement. That is, if left is the
current auto placement, right is set instead and the other way round.
0.5
0.6
0.6
0.7
0.4
0.8
\begin{tikzpicture}[auto]
\draw[help lines,use as bounding box] (0,-.5) grid (4,5);
0.4
0.3
0.2
0.8
0.2
0.9
\draw (0.5,0) .. controls (9,6) and (-5,6) .. (3.5,0)
node foreach \pos in {0,0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9,1}
[pos=\pos,swap,fill=red!20] {\pos}
node foreach \pos in {0.025,0.2,0.4,0.6,0.8,0.975}
[pos=\pos,fill=blue!20] {\pos};
\end{tikzpicture}
0.1
0.025
0.975
0
1
\begin{tikzpicture}[shorten >=1pt,node distance=2cm,auto]
\draw[help lines] (0,0) grid (3,2);
0
\node[state]
\node[state]
\node[state]
\node[state]
q1
0
1
q0
q3
1
0
q2
(q_0)
(q_1) [above right of=q_0]
(q_2) [below right of=q_0]
(q_3) [below right of=q_1]
\path[->] (q_0) edge
edge
(q_1) edge
edge [loop above]
(q_2) edge
edge [loop below]
\end{tikzpicture}
1
236
{$q_0$};
{$q_1$};
{$q_2$};
{$q_3$};
node
{0} (q_1)
node [swap] {1} (q_2)
node
{1} (q_3)
node
{0} ()
node [swap] {0} (q_3)
node
{1} ();
(no value)
/tikz/’
This is a very short alias for swap.
(no value)
/tikz/sloped
This option causes the node to be rotated such that a horizontal line becomes a tangent to the curve.
The rotation is normally done in such a way that text is never “upside down.” To get upside-down text,
use can use [rotate=180] or [allow upside down], see below.
1
\tikz \draw (0,0) .. controls +(up:2cm) and +(left:2cm) .. (1,3)
node foreach \p in {0,0.25,...,1} [sloped,above,pos=\p]{\p};
0.5
5
0.7
0
0.25
\begin{tikzpicture}[->]
\draw (0,0)
-- (2,0.5) node[midway,sloped,above] {$x$};
\draw (2,-.5) -- (0,0)
node[midway,sloped,below] {$y$};
\end{tikzpicture}
x
y
(default true, initially false)
/tikz/allow upside down=hbooleani
If set to true, Tik Z will not “righten” upside down text.
5
1
\tikz [allow upside down]
\draw (0,0) .. controls +(up:2cm) and +(left:2cm) .. (1,3)
node foreach \p in {0,0.25,...,1} [sloped,above,pos=\p]{\p};
0
0.25
0.5
0.7
x
\begin{tikzpicture}[->,allow upside down]
\draw (0,0)
-- (2,0.5) node[midway,sloped,above] {$x$};
\draw (2,-.5) -- (0,0)
node[midway,sloped,below] {$y$};
\end{tikzpicture}
y
There exist styles for specifying positions a bit less “technically”:
(style, no value)
/tikz/midway
This has the same effect as pos=0.5.
end
very nearatend
near end
midway
\tikz \draw (0,0) .. controls +(up:2cm) and +(left:3cm) .. (1,5)
node[at end]
{\texttt{at end}}
node[very near end]
{\texttt{very near end}}
node[near end]
{\texttt{near end}}
node[midway]
{\texttt{midway}}
node[near start]
{\texttt{near start}}
node[very near start] {\texttt{very near start}}
node[at start]
{\texttt{at start}};
near start
very near start
at start
237
(style, no value)
/tikz/near start
Set to pos=0.25.
(style, no value)
/tikz/near end
Set to pos=0.75.
(style, no value)
/tikz/very near start
Set to pos=0.125.
(style, no value)
/tikz/very near end
Set to pos=0.875.
(style, no value)
/tikz/at start
Set to pos=0.
(style, no value)
/tikz/at end
Set to pos=1.
17.9
Placing Nodes on a Line or Curve Implicitly
When you wish to place a node on the line (0,0) --(1,1), it is natural to specify the node not following
the (1,1), but “somewhere in the middle.” This is, indeed, possible and you can write (0,0) --node{a}
(1,1) to place a node midway between (0,0) and (1,1).
What happens is the following: The syntax of the line-to path operation is actually -- nodehnode
specificationihcoordinatei. (It is even possible to give multiple nodes in this way.) When the optional node
is encountered, that is, when the -- is directly followed by node, then the specification(s) are read and
“stored away.” Then, after the hcoordinatei has finally been reached, they are inserted again, but with the
pos option set.
There are two things to note about this: When a node specification is “stored,” its catcodes become
fixed. This means that you cannot use overly complicated verbatim text in them. If you really need, say, a
verbatim text, you will have to put it in a normal node following the coordinate and add the pos option.
Second, which pos is chosen for the node? The position is inherited from the surrounding scope. However,
this holds only for nodes specified in this implicit way. Thus, if you add the option [near end] to a scope,
this does not mean that all nodes given in this scope will be put on near the end of lines. Only the nodes
for which an implicit pos is added will be placed near the end. Typically, this is what you want. Here are
some examples that should make this clearer:
A
B
C
D
\begin{tikzpicture}[near end]
\draw (0cm,4em) -- (3cm,4em)
\draw (0cm,3em) -\draw (0cm,2em) -\draw (0cm,1em) -- (3cm,1em)
\end{tikzpicture}
node{A};
node{B}
(3cm,3em);
node[midway] {C} (3cm,2em);
node[midway] {D} ;
Like the line-to operation, the curve-to operation .. also allows you to specify nodes “inside” the operation.
After both the first .. and also after the second .. you can place node specifications. Like for the -operation, these will be collected and then reinserted after the operation with the pos option set.
17.10
The Label and Pin Options
17.10.1
Overview
In addition to the node path operation, the two options label and pin can be used to “add a node next to
another node”. As an example, suppose we want to draw a graph in which the nodes are small circles:
\tikz [circle]
\node [draw]
\node [draw]
\node [draw]
\node [draw]
}
{
(s)
(a)
(b)
(t)
{};
[right=of s] {} edge (s);
[right=of a] {} edge (a);
[right=of b] {} edge (b);
238
Now, in the above example, suppose we wish to indicate that the first node is the start node and the last
node is the target node. We could write \node (s) {$s$};, but this would enlarge the first node. Rather,
we want the “s” to be placed next to the node. For this, we need to create another node, but next to the
existing node. The label and pin option allow us to do exactly this without having to use the cumbersome
node syntax:
s
t
\tikz [circle]
\node [draw]
\node [draw]
\node [draw]
\node [draw]
}
17.10.2
{
(s)
(a)
(b)
(t)
[label=$s$]
[right=of s]
[right=of a]
[right=of b,
{};
{} edge (s);
{} edge (a);
label=$t$] {} edge (b);
The Label Option
(no default)
/tikz/label=[hoptionsi]hanglei:htexti
When this option is given to a node operation, it causes another node to be added to the path after
the current node has been finished. This extra node will have the text htexti. It is placed, in principle,
in the direction hanglei relative to the main node, but the exact rules are a bit complex. Suppose the
node currently under construction is called main node and let us call the label node label node. Then
the following happens:
1. The hanglei is used to determine a position on the border of the main node. If the hanglei is
missing, the value of the following key is used instead:
(no default, initially above)
/tikz/label position=hanglei
Sets the default position for labels.
The hanglei determines the position on the border of the shape in two different ways. Normally, the
border position is given by main node.hanglei. This means that the hanglei can either be a number
like 0 or -340, but it can also be an anchor like north. Additionally, the special angles above,
below, left, right, above left, and so on are automatically replaced by the corresponding angles
90, 270, 180, 0, 135, and so on.
A special case arises when the following key is set:
/tikz/absolute=htrue or falsei
(default true)
When this key is set, the hanglei is interpreted differently: We still use a point on the border of
the main node, but the angle is measured “absolutely,” that is, an angle of 0 refers to the point
on the border that lies on a straight line from the main node’s center to the right (relative to
the paper, not relative to the local coordinate system of either the node or the scope).
The difference can be seen in the following example:
ode
main n
\tikz [rotate=-80,every label/.style={draw,red}]
\node [transform shape,rectangle,draw,label=right:label] {main node};
label
ode
main n
\tikz [rotate=-80,every label/.style={draw,red},absolute]
\node [transform shape,rectangle,draw,label=right:label] {main node};
label
2. Then, an anchor point for the label node is computed. It is determined in such a way that the
label node will “face away” from the border of the main node. The anchor that is chosen depends
on the position of the border point that is chosen and its position relative to the center of the main
239
node and on whether the transform shape option is set. In detail, when the computed border
point is at 0◦ , the anchor west will be used. Similarly, when the border point is at 90◦ , the anchor
south will be used, and so on for 180◦ and 270◦ .
For angles between these “major” angles, like 30◦ or 110◦ , combined anchors, like south west for
30◦ or south east for 110◦ , are used. However, for angles close to the major angles, (differing
by up to 2◦ from the major angle), the anchor for the major angle is used. Thus, a label at a
border point for 2◦ will have the anchor west, while a label for 3◦ will have the anchor south
west, resulting in a “jump” of the anchor. You can set the anchor “by hand” using the anchor key
or indirect keys like left.
default 60◦
115◦
3◦
my
circle 2◦
◦
180
−90◦
\tikz
\node [circle, draw,
label=default,
label=60:$60^\circ$,
label=below:$-90^\circ$,
label=3:$3^\circ$,
label=2:$2^\circ$,
label={[below]180:$180^\circ$},
label={[centered]135:$115^\circ$}] {my circle};
main node
3. One hanglei is special: If you set the hanglei to center, then the label will be placed on the center
of the main node. This is mainly useful for adding a label text to an existing node, especially if it
has been rotated.
\tikz \node [transform shape,rotate=90,
rectangle,draw,label={[red]center:R}] {main node};
R
You can pass hoptionsi to the node label node. For this, you provide the options in square brackets
before the hanglei. If you do so, you need to add braces around the whole argument of the label
option and this is also the case if you have brackets or commas or semicolons or anything special in the
htexti.
\tikz \node [circle,draw,label={[red]above:X}] {my circle};
X
my circle
\begin{tikzpicture}
\node [circle,draw,label={[name=label node]above left:$a,b$}] {};
\draw (label node) -- +(1,1);
\end{tikzpicture}
a, b
If you provide multiple label options, then multiple extra label nodes are added in the order they are
given.
The following styles influence how labels are drawn:
(no default, initially 0pt)
/tikz/label distance=hdistancei
The hdistancei is additionally inserted between the main node and the label node.
\tikz[label distance=5mm]
\node [circle,draw,label=right:X,
label=above right:Y,
label=above:Z]
{my circle};
Z
Y
my circle
X
240
(style, initially empty)
/tikz/every label
This style is used in every node created by the label option. The default is draw=none,fill=none.
See Section 17.10.4 for an easier syntax for specifying nodes.
17.10.3
The Pin Option
(no default)
/tikz/pin=[hoptionsi]hanglei:htexti
This option is quite similar to the label option, but there is one difference: In addition to adding an
extra node to the picture, it also adds an edge from this node to the main node. This causes the node
to look like a pin that has been added to the main node:
q0
\tikz \node [circle,fill=blue!50,minimum size=1cm,pin=60:$q_0$] {};
The meaning of the hoptionsi and the hanglei and the htexti is exactly the same as for the node option.
Only, the options and styles the influence the way pins look are different:
(no default, initially 3ex)
/tikz/pin distance=hdistancei
This hdistancei is used instead of the label distance for the distance between the main node and
the label node.
\tikz[pin distance=1cm]
\node [circle,draw,pin=right:X,
pin=above right:Y,
pin=above:Z]
{my circle};
Z
Y
my circle
X
(style, initially draw=none,fill=none)
/tikz/every pin
This style is used in every node created by the pin option.
(no default, initially above)
/tikz/pin position=hanglei
The default pin position. Works like label position.
(style, initially help lines)
/tikz/every pin edge
This style is used in every edge created by the pin options.
\tikz [pin distance=15mm,
every pin edge/.style={<-,shorten <=1pt,decorate,
decoration={snake,pre length=4pt}}]
\node [circle,draw,pin=right:X,
pin=above right:Y,
pin=above:Z]
{my circle};
Z
Y
my circle
X
(no default, initially empty)
/tikz/pin edge=hoptionsi
This option can be used to set the options that are to be used in the edge created by the pin
option.
241
\tikz[pin distance=10mm]
\node [circle,draw,pin={[pin edge={blue,thick}]right:X},
pin=above:Z]
{my circle};
Z
my circle
start
17.10.4
X
my circle
\tikz [every pin edge/.style={},
initial/.style={pin={[pin distance=5mm,
pin edge={<-,shorten <=1pt}]left:start}}]
\node [circle,draw,initial] {my circle};
The Quotes Syntax
The label and pin option provide a syntax for creating nodes next to existing nodes, but this syntax is
often a bit too verbose. By including the following library, you get access to an even more concise syntax:
Tik Z Library quotes
\usetikzlibrary{quotes} % LATEX and plain TEX
\usetikzlibrary[quotes] % ConTEXt
Enables the quotes syntax for labels, pins, edge nodes, and pic texts.
Let us start with the basics of what this library does: Once loaded, inside the options of a node command,
instead of the usual hkeyi=hvaluei pairs, you may also provide strings of the following form (the actual syntax
slightly more general, see the detailed descriptions later on):
"htexti"hoptionsi
The hoptionsi must be surrounded in curly braces when they contain a comma, otherwise the curly braces
are optional. The may be preceded by an optional space.
When a hstringi of the above form is encountered inside the options of a node, then it is internally
transformed to
label={[]hoptionsi]htexti}
Let us have a look at an example:
my label
\tikz \node ["my label" red, draw] {my node};
my node
The above has the same effect as the following:
my label
\tikz \node [label={[red]my label}, draw] {my node};
my node
Here are further examples, one where no hoptionsi are added to the label, one where a position is
specified, and examples with more complicated options in curly braces:
242
label
A
label B
label
C
\begin{tikzpicture}
\matrix [row sep=5mm] {
\node [draw, "label"]
\node [draw, "label" left]
\node [draw, "label" centered]
\node [draw, "label" color=red]
\node [draw, "label" {red,draw,thick}]
};
\end{tikzpicture}
{A};
{B};
{C};
{D};
{E};
\\
\\
\\
\\
\\
label
D
label
E
Let us now have a more detailed look at what which commands this library provides:
(no value)
/tikz/quotes mean label
When this option is used (which is the default when this library is loaded), then, as described above,
inside the options of a node a special syntax check is done.
The syntax. For each string in the list of options it is tested whether it starts with a quotation mark
(note that this will never happen for normal keys since the normal keys of Tik Z do not start with
quotation marks). When this happens, the hstringi should not be a key–value pair, but, rather, must
have the form:
"htexti"’hoptionsi
(We will discuss the optional apostrophe in a moment. It is not really important for the current option,
but only for edge labels, which are discussed later).
Transformation to a label option. When a hstringi has the above form, it is treated (almost) as if
you had written
label={[]hoptionsi]htexti}
instead. The “almost” refers to the following additional feature: In reality, before the hoptionsi are
executed inside the label command, the direction keys above, left, below right and so on are
redefined so that above is a shorthand for label position=90 and similarly for the other keys. The
net effect is that in order to specify the position of the htexti relative to the main node you can just put
something like left or above right inside the hoptionsi:
90◦
\tikz
\node ["$90^\circ$" above, "$180^\circ$" left, circle, draw] {circle};
180◦ circle
Alternatively, you can also use hdirectioni:hactual texti as your htexti. This works since the label
command allows you to specify a direction at the beginning when it is separated by a colon:
90◦
\tikz
\node ["90:$90^\circ$", "left:$180^\circ$", circle, draw] {circle};
180◦ circle
Arguably, placing above or left behind the htexti seems more natural than having it inside the htexti.
In addition to the above, before the hoptionsi are executed, the following style is also executed:
(style, no value)
/tikz/every label quotes
243
90◦
\tikz [every label quotes/.style=red]
\node ["90:$90^\circ$", "left:$180^\circ$", circle, draw] {circle};
180◦ circle
Handling commas and colons inside the text. The htexti may not contain a comma, unless it is
inside curly braces. The reason is that the key handler separates the total options of a node along the
commas it finds. So, in order to have text containing a comma, just add curly braces around either the
comma or just around the whole htexti:
yes, we can
\tikz \node ["{yes, we can}", draw] {foo};
foo
The same is true for a colon, only in this case you may need to surround specifically the colon by curly
braces to stop the label option from interpreting everything before the colon as a direction:
yes: we can
\tikz \node ["yes{:} we can", draw] {foo};
foo
The optional apostrophe. Following the closing quotation marks in a hstringi there may (but need
not) be a single quotation mark (an apostrophe), possibly surrounded by whitespaces. If it is present,
it is simply added to the hoptionsi as another option (and, indeed, a single apostrophe is a legal option
in Tik Z, it is a shorthand for swap):
String
has the same effect as
"foo"’
"foo" {’}
"foo"’ red
"foo" {’,red}
"foo"’{red}
"foo" {’,red}
"foo"{’,red} "foo" {’,red}
"foo"{red,’} "foo" {red,’}
"foo"{’red}
"foo" {’red} (illegal; there is no key ’red)
"foo" red’
"foo" {red’} (illegal; there is no key red’)
(no value)
/tikz/quotes mean pin
This option has exactly the same effect as quotes mean label, only instead of transforming quoted
text to the label option, they get transformed to the pin option:
90◦
180◦
\tikz [quotes mean pin]
\node ["$90^\circ$" above, "$180^\circ$" left, circle, draw] {circle};
circle
Instead of every label quotes, the following style is executed with each such pin:
(style, no value)
/tikz/every pin quotes
If instead of labels or pins you would like quoted strings to be interpreted in a different manner, you
can also define your own handlers:
/tikz/node quotes mean=hreplacementi
(no default)
This key allows you to define your own handler for quotes options. Inside the options of a node, whenever
a key–value pair with the syntax
"htexti"’hoptionsi
244
is encountered, the following happens: The above string gets replaced by hreplacementi where inside
the hreplacementi the parameter #1 is htexti and #2 is hoptionsi. If the apostrophe is present (see also
the discussion of quotes mean label), the hoptionsi start with ’,.
The hreplacementi is then parsed normally as options (using \pgfkeys).
Here is an example, where the quotes are used to define labels that are automatically named according
to the text:
\tikzset{node quotes mean={label={[#2,name={#1}]#1}}}
1
2 circle
\tikz {
\node ["1", "2" label position=left, circle, draw] {circle};
\draw (1) -- (2);
}
Some further options provided by the quotes library concern labels next to edges rather than nodes and
they are described in Section 17.12.2.
17.11
Connecting Nodes: Using Nodes as Coordinates
Once you have defined a node and given it a name, you can use this name to reference it. This can be
done in two ways, see also Section 13.2.3. Suppose you have said \path(0,0) node(x) {Hello World!};
in order to define a node named x.
1. Once the node x has been defined, you can use (x.hanchor i) wherever you would normally use a
normal coordinate. This will yield the position at which the given hanchor i is in the picture. Note
that transformations do not apply to this coordinate, that is, (x.north) will be the northern anchor
of x even if you have said scale=3 or xshift=4cm. This is usually what you would expect.
2. You can also just use (x) as a coordinate. In most cases, this gives the same coordinate as (x.center).
Indeed, if the shape of x is coordinate, then (x) and (x.center) have exactly the same effect.
However, for most other shapes, some path construction operations like -- try to be “clever” when they
are asked to draw a line from such a coordinate or to such a coordinate. When you say (x)--(1,1),
the -- path operation will not draw a line from the center of x, but from the border of x in the direction
going towards (1,1). Likewise, (1,1)--(x) will also have the line end on the border in the direction
coming from (1,1).
In addition to --, the curve-to path operation .. and the path operations -| and |- will also handle
nodes without anchors correctly. Here is an example, see also Section 13.2.3:
label
Hello World!
R2
1
xdx
label
\begin{tikzpicture}
\path (0,0) node
(x) {Hello World!}
(3,1) node[circle,draw](y) {$\int_1^2 x \mathrm d x$};
\draw[->,blue]
(x) -- (y);
\draw[->,red]
(x) -| node[near start,below] {label} (y);
\draw[->,orange] (x) .. controls +(up:1cm) and +(left:1cm) .. node[above,sloped] {label} (y);
\end{tikzpicture}
17.12
Connecting Nodes: Using the Edge Operation
17.12.1
Basic Syntax of the Edge Operation
The edge operation works like a to operation that is added after the main path has been drawn, much like
a node is added after the main path has been drawn. This allows each edge to have a different appearance.
As the node operation, an edge temporarily suspends the construction of the current path and a new path
p is constructed. This new path p will be drawn after the main path has been drawn. Note that p can be
245
totally different from the main path with respect to its options. Also note that if there are several to and/or
node operations in the main path, each creates its own path(s) and they are drawn in the order that they
are encountered on the main path.
\path . . . edge[hoptionsi] hnodesi (hcoordinatei) . . . ;
The effect of the edge operation is that after the main path the following path is added to the picture:
\path[every edge,hoptionsi] (\tikztostart) hpathi;
Here, hpathi is the to path. Note that, unlike the path added by the to operation, the (\tikztostart)
is added before the hpathi (which is unnecessary for the to operation, since this coordinate is already
part of the main path).
The \tikztostart is the last coordinate on the path just before the edge operation, just as for the node
or to operations. However, there is one exception to this rule: If the edge operation is directly preceded
by a node operation, then this just-declared node is the start coordinate (and not, as would normally
be the case, the coordinate where this just-declared node is placed – a small, but subtle difference). In
this regard, edge differs from both node and to.
If there are several edge operations in a row, the start coordinate is the same for all of them as their
target coordinates are not, after all, part of the main path. The start coordinate is, thus, the coordinate
preceding the first edge operation. This is similar to nodes insofar as the edge operation does not
modify the current path at all. In particular, it does not change the last coordinate visited, see the
following example:
b
c
a
d
\begin{tikzpicture}
\node (a) at
(0:1) {$a$};
\node (b) at (90:1) {$b$} edge [->]
\node (c) at (180:1) {$c$} edge [->]
edge [<-]
\node (d) at (270:1) {$d$} edge [->]
edge [dotted]
edge [<-]
\end{tikzpicture}
(a);
(a)
(b);
(a)
(b)
(c);
A different way of specifying the above graph using the edge operation is the following:
\begin{tikzpicture}
\node foreach \name/\angle in {a/0,b/90,c/180,d/270}
(\name) at (\angle:1) {$\name$};
b
c
a
d
\path[->] (b) edge
edge
edge
(c) edge
edge
(d) edge
\end{tikzpicture}
(a)
(c)
[-,dotted] (d)
(a)
(d)
(a);
As can be seen, the path of the edge operation inherits the options from the main path, but you can
locally overrule them.
\begin{tikzpicture}
\node foreach \name/\angle in {a/0,b/90,c/180,d/270}
(\name) at (\angle:1.5) {$\name$};
b
5
missing
a
ve
r
ba y
d
c
d
\path[->] (b) edge
node[above right]
edge
edge [-,dotted] node[below,sloped]
(c) edge
edge
(d) edge [red]
node[above,sloped]
node[below,sloped]
\end{tikzpicture}
{$5$}
(a)
(c)
{missing} (d)
(a)
(d)
{very}
{bad}
(a);
Instead of every to, the style every edge is installed at the beginning of the main path.
(style, initially draw)
/tikz/every edge
Executed for each edge.
246
\begin{tikzpicture}[every to/.style={draw,dashed}]
\path (0,0) edge (3,2);
\end{tikzpicture}
17.12.2
Nodes on Edges: Quotes Syntax
The standard way of specifying nodes that are placed “on” an edge (or on a to-path; all of the following is
also true for to–paths) is to put node specifications after the edge keyword, but before the target coordinate.
Another way is to use the edge node option and its friends. Yet another way is to use the quotes syntax.
The syntax is essentially the same as for labels added to nodes as described in Section 17.10.4 and you
also need to load the quotes library.
In detail, when the quotes library is loaded, each time a key–value pair in a list of options passed to
an edge or a to path command starts with ", the key–value pair must actually be a string of the following
form:
"htexti"’hoptionsi
This string is transformed into the following:
edge node=node [every edge quotes]hoptionsi]{htexti}
As described in Section 17.10.4, the apostrophe becomes part of the hoptionsi, when present.
The following style is important for the placement of the labels:
(style, initially auto)
/tikz/every edge quotes
This style is auto by default, which causes labels specified using the quotes-syntax to be placed next to
the edges. Unless the setting of auto has been changed, they will be placed to the left.
left
\tikz \draw (0,0) edge ["left", ->] (2,0);
In order to place all labels to the right by default, change this style to auto=right:
right
\tikz [every edge quotes/.style={auto=right}]
\draw (0,0) edge ["right", ->] (2,0);
To place all nodes “on” the edge, just make this style empty (and, possibly, make your labels opaque):
mid
\tikz [every edge quotes/.style={fill=white,font=\footnotesize}]
\draw (0,0) edge ["mid", ->] (2,1);
You may often wish to place some edge nodes to the right of edges and some to the left. For this, the
special treatment of the apostrophe is particularly convenient: Recall that in Tik Z there is an option just
called ’, which is a shorthand for swap. Now, following the closing quotation mark come the options of an
edge node. Thus, if the closing quotation mark is followed by an apostrophe, the swap option will be added
to the edge label, causing it is be placed on the other side. Because of the special treatment, you can even
add another option like near end after the apostrophe without having to add curly braces and commas:
start
left
right
end
\tikz
\draw (0,0) edge ["left", "right"’,
"start" near start,
"end"’ near end] (4,0);
In order to modify the distance between the edge labels and the edge, you should consider introducing
some styles:
start
left
right
\tikz [tight/.style={inner sep=1pt}, loose/.style={inner sep=.7em}]
\draw (0,0) edge ["left"
tight,
"right"’ loose,
"start" near start] (4,0);
247
17.13
Referencing Nodes Outside the Current Picture
17.13.1
Referencing a Node in a Different Picture
It is possible (but not quite trivial) to reference nodes in pictures other than the current one. This means
that you can create a picture and a node therein and, later, you can draw a line from some other position
to this node.
To reference nodes in different pictures, proceed as follows:
1. You need to add the remember picture option to all pictures that contain nodes that you wish to
reference and also to all pictures from which you wish to reference a node in another picture.
2. You need to add the overlay option to paths or to whole pictures that contain references to nodes in
different pictures. (This option switches the computation of the bounding box off.)
3. You need to use a driver that supports picture remembering and you need to run TEX twice.
(For more details on what is going on behind the scenes, see Section 101.3.2.)
Let us have a look at the effect of these options.
(no default, initially false)
/tikz/remember picture=hbooleani
This option tells Tik Z that it should attempt to remember the position of the current picture on the
page. This attempt may fail depending on which backend driver is used. Also, even if remembering
works, the position may only be available on a second run of TEX.
Provided that remembering works, you may consider saying
\tikzstyle{every picture}+=[remember picture]
to make Tik Z remember all pictures. This will add one line in the .aux file for each picture in your
document – which typically is not very much. Then, you do not have to worry about remembered
pictures at all.
/tikz/overlay=hbooleani
(default true)
This option is mainly intended for use when nodes in other pictures are referenced, but you can also use
it in other situations. The effect of this option is that everything within the current scope is not taken
into consideration when the bounding box of the current picture is computed.
You need to specify this option on all paths (or at least on all parts of paths) that contain a reference
to a node in another picture. The reason is that, otherwise, Tik Z will attempt to make the current
picture large enough to encompass the node in the other picture. However, on a second run of TEX this
will create an even bigger picture, leading to larger and larger pictures. Unless you know what you are
doing, I suggest specifying the overlay option with all pictures that contain references to other pictures.
Let us now have a look at a few examples. These examples work only if this document is processed with
a driver that supports picture remembering.
248
Inside the current text we place two pictures, containing nodes named n1 and n2, using
\tikz[remember picture] \node[circle,fill=red!50] (n1) {};
which yields
, and
\tikz[remember picture] \node[fill=blue!50] (n2) {};
yielding the node . To connect these nodes, we create another picture using the overlay option and also
the remember picture option.
\begin{tikzpicture}[remember picture,overlay]
\draw[->,very thick] (n1) -- (n2);
\end{tikzpicture}
ple
Note that the last picture is seemingly empty. What happens is that it has zero size and contains an arrow
that lies well outside its bounds. As a last example, we connect a node in another picture to the first two
nodes. Here, we provide the overlay option only with the line that we do not wish to count as part of the
picture.
\begin{tikzpicture}[remember picture]
\node (c) [circle,draw] {Big circle};
Big circle
17.13.2
\draw [overlay,->,very thick,red,opacity=.5]
(c) to[bend left] (n1) (n1) -| (n2);
\end{tikzpicture}
Referencing the Current Page Node – Absolute Positioning
Ex
am
There is a special node called current page that can be used to access the current page. It is a node
of shape rectangle whose south west anchor is the lower left corner of the page and whose north east
anchor is the upper right corner of the page. While this node is handled in a special way internally, you can
reference it as if it were defined in some remembered picture other than the current one. Thus, by giving
the remember picture and the overlay options to a picture, you can position nodes absolutely on a page.
The first example places some text in the lower left corner of the current page:
\begin{tikzpicture}[remember picture,overlay]
\node [xshift=1cm,yshift=1cm] at (current page.south west)
[text width=7cm,fill=red!20,rounded corners,above right]
{
This is an absolutely positioned text in the
lower left corner. No shipout-hackery is used.
};
\end{tikzpicture}
The next example adds a circle in the middle of the page.
\begin{tikzpicture}[remember picture,overlay]
\draw [line width=1mm,opacity=.25]
(current page.center) circle (3cm);
\end{tikzpicture}
The final example overlays some text over the page (depending on where this example is found on the
page, the text may also be behind the page).
\begin{tikzpicture}[remember picture,overlay]
\node [rotate=60,scale=10,text opacity=0.2]
at (current page.center) {Example};
\end{tikzpicture}
17.14
Late Code and Late Options
All options given to a node only locally affect this one node. While this is a blessing in most cases, you may
sometimes want to cause options to have effects “later” on. The other way round, you may sometimes note
“only later” that some options should be added to the options of a node. For this, the following version of
the node path command can be used:
This is an absolutely positioned text in the
lower left corner. No shipout-hackery is
used.
249
\path . . . node also[hlate optionsi](hnamei) . . . ;
Note that the hnamei is compulsory and that no text may be given. Also, the ordering of options and
node label must be as above.
The effect of the above is the following effect: The node hnamei must already be existing. Now, the
hlate optionsi are executed in a local scope. Most of these options will have no effect since you cannot
change the appearance of the node, that is, you cannot change a red node into a green node using these
“late” options. However, giving the append after command and prefix after command options inside
the hlate optionsi (directly or indirectly) does have the desired effect: The given path gets executed
with the \tikzlastnode set to the determined node.
The net effect of all this is that you can provide, say, the label option inside the hoptionsi to a add a
label to a node that has already been constructed.
world
Hello
\begin{tikzpicture}
\node
[draw,circle]
(a) {Hello};
\node also [label=above:world] (a);
\end{tikzpicture}
As explained in Section 14, you can use the options append after command and prefix after command
to add a path after a node. The following macro may be useful there:
\tikzlastnode
Expands to the last node on the path.
Instead of the node also syntax, you can also the following option:
/tikz/late options=hoptionsi
(no default)
This option can be given on a path (but not as an argument to a node path command) and has the
same effect as the node also path command. Inside the hoptionsi, you should use the name option to
specify the node for which you wish to add late options:
world
Hello
\begin{tikzpicture}
\node
[draw,circle]
(a) {Hello};
\path [late options={name=a, label=above:world}];
\end{tikzpicture}
250
18
Pics: Small Pictures on Paths
18.1
Overview
A “pic” is a “short picture” (hence the short name. . . ) that can be inserted anywhere in Tik Z picture where
you could also insert a node. Similarly to nodes, pics have a “shape” (called type to avoid confusion) that
someone has defined. Each time a pic of a specified type is used, the type’s code is executed, resulting in
some drawings to be added to the current picture. The syntax for adding nodes and adding pics to a picture
are also very similar. The core difference is that pics are typically more complex than nodes and may consist
of a whole bunch of nodes themselves together with complex paths joining them.
As a very simple example, suppose we want to define a pic type seagull that just draw “two bumps.”
The code for this definition is quite easy:
\tikzset{
seagull/.pic={
% Code for a "seagull". Do you see it?...
\draw (-3mm,0) to [bend left] (0,0) to [bend left] (3mm,0);
}
}
The first line just tells TEX that you set some Tik Z options for the current scope (which is the whole
document); you could put seagull/.pic=... anywhere else where Tik Z options are allowed (which is just
about anywhere). We have now defined a seagull pic type and can use it as follows:
\tikz \fill [fill=blue!20]
(1,1)
-- (2,2) pic
-- (3,2) pic
-- (3,1) pic [rotate=30]
-- (2,1) pic [red]
{seagull}
{seagull}
{seagull}
{seagull};
As can be see, defining new types of pics is much easier than defining new shapes for nodes; but see
Section 18.3 for the fine details.
Since defining new pics types is easier than defining new node shapes and since using pics is as easy as
using nodes, why should you use nodes at all? There are chiefly two reasons:
1. Unlike nodes, pics cannot be referenced later on. You can reference nodes that are inside a pic, but not
“the pic itself.” In particular, you cannot draw lines between pics the way you can draw them between
nodes. In general, whenever it makes sense that some drawing could conceivably be connected to other
node-like-things, then a node is better than a pic.
2. If pics are used to emulate the full power of a node (which is possible, in principle), they will be slower
to construct and take up more memory than a node achieving the same effect.
Despite these drawbacks, pics are an excellent choice for creating highly configurable reusable pieces of
drawings that can be inserted into larger contexts.
18.2
The Pic Syntax
\pic
Inside {tikzpicture} this is an abbreviation for \path pic.
The syntax for adding a pic to a picture is very similar to the syntax used for nodes (indeed, internally the
same parser code is used). The main difference is that instead of a node contents you provide the picture’s
type between the braces:
\path . . . pichforeach statementsi[hoptionsi](hprefix i)at(hcoordinatei){hpic typei} . . . ;
Adds a pic to the current Tik Z picture of the specified hpic typei. The effect is, basically, that some
code associated with the hpic typei is executed (how this works, exactly, is explained later). This code
can consist of arbitrary Tik Z code. As for nodes, the current path will not be modified by this path
command, all drawings produced by the code are “external” to the path the same way neither a node
nor its border are part of the path on which they are specified.
Just like the node command, this path operation is somewhat complex and we go over it step by step.
251
Order of the parts of the specification. Just like for nodes, everything between “pic” and the
opening brace of the hpic typei is optional and can be given in any order. If there are hforeach statementsi,
they must come first, directly following “pic.” As for nodes, the “end” of the pic specification is normally
detected by the presence of the opening brace. You can, however, use the pic type option to specify
the pic type as an option.
/tikz/pic type=hpic typei
(no default)
This key sets the pic type of the current pic. When this option is used inside an option block
of a pic, the parsing of the pic ends immediately and no pic type in braces is expected. (In
other words, this option behaves exactly like the node contents option and, indeed, the two are
interchangeable.)
\tikz {
\path (0,0) pic [pic type = seagull]
(1,0) pic
{seagull};
}
The location of a pic. Just like nodes, pics are placed at the last position mentioned on the path or,
when at is used, at a specified position. “Placing” a pic somewhere actually means that the coordinate
system is translated (shifted) to this last position. This means that inside of the pic type’s code any
mentioning of the origin refers to the last position used on the path or to the specified at.
\tikz {
\draw
\pic
\path
\pic
}
% different ways of placing pics
[help lines] (0,0) grid (3,2);
at (1,0)
{seagull};
(2,1)
pic {seagull};
[at={(3,2)}] {seagull};
As for nodes, except for the described shifting, the coordinate system of a pic is reset prior to executing
the pic type’s code. This can be changed using the transform shape option, which has the same effect
as for nodes: The “outer” transformation gets applied to the node:
\tikz [scale=2] {
\pic at (0,0)
{seagull};
\pic at (1,0) [transform shape] {seagull};
}
When the hoptionsi contain transformation commands like scale or rotate, these transformations
always apply to the pic:
\tikz [rotate=30] {
\pic at (0,0)
{seagull};
\pic at (1,0) [rotate=90] {seagull};
}
Just like nodes, pics can also be positioned implicitly and, somewhat unsurprisingly, the same rules
concerning positioning and sloping apply:
\tikz \draw
(0,0) to [bend left]
pic [near start]
{seagull}
pic
{seagull}
pic [sloped, near end] {seagull} (4,0);
The options of a node. As always, any given hoptionsi apply only to the pic and have no effect
outside. As for nodes, most “outside” options also apply to the pics, but not the “action” options like
draw or fill. These must be given in the hoptionsi of the pic.
The code of a pic. As stated earlier, the main job of a pic is to execute some code in a scope that
is shifted according to the last point on the path or to the at position specified in the pic. It was also
claimed that this code is specified by the hpic typei. However, this specification is somewhat indirect.
What really happens is the following: When a pic is encountered, the current path is suspended and
a new internal scope is started. The hoptionsi are executed and also the hpic typei (as explained in a
moment). After all this is done, the code stored in the following key gets executed:
252
(no default)
/tikz/pics/code=hcodei
This key stores the hcodei that should be drawn in the current pic. Normally, setting this key is
done by the hpic typei, but you can also set it in the hoptionsi and leave the hpic typei empty:
\tikz \pic [pics/code={\draw (-3mm,0) to[bend left] (0,0)
to[bend left] (3mm,0);}]
{}; % no pic type specified
Now, how does the hpic typei set pics/code? It turns out that the hpic typei is actually just a list of keys
that are executed with the prefix /tikz/pics/. In the above examples, this “list of keys” just consisted
of the single key “seagull” that did not take any arguments, but, in principle, you could provide any
arbitrary text understood by \pgfkeys here. This means that when we write pic{seagull}, Tik Z will
execute the key /tikz/pics/seagull. It turns out, see Section 18.3, that this key is just a style set to
code={\draw(-3mm,0)...;}. Thus, pic{seagull} will cause the pics/code key to be set to the text
needed to draw the seagull.
Indeed, you can also use the hpic typei simply to set the code of the pic. This is useful for cases when
you have some code that you “just want to execute, but do not want to define a new pic type.” Here is
a typical example where we use pics to add some markings to a path:
\tikz \draw (0,0) .. controls(1,0) and (2,1) .. (3,1)
foreach \t in {0, 0.1, ..., 1} {
pic [pos=\t] {code={\draw circle [radius=2pt];}}
};
In our seagull example, we always explicitly used \draw to draw the seagull. This implies that when a
user writes something pic[fill]{seagull} in the hope of having a “filled” seagull, nothing special will
happen: The \draw inside the pic explicitly states that the path should be drawn, not filled, and the
fact that in the surrounding scope the fill option is set has no effect. The following key can be used
to change this:
(no value)
/tikz/pic actions
This key is a style that can be used (only) inside the code of a pic. There, it will set the “action”
keys set inside the hoptionsi of the pic (“actions” are drawing, filling, shading, and clipping or any
combination thereof).
To see how this key works, let us define the following pic:
\tikzset{
my pic/.pic = {
\path [pic actions] (0,0) circle[radius=3mm];
\draw (-3mm,-3mm) rectangle (3mm,3mm);
}
}
In the code, whether or not the circle gets drawn/filled/shaded depends on which options where
given to the pic command when it is used. In contrast, the rectangle will always (just) be
drawn.
\tikz
\tikz
\tikz
\tikz
\tikz
\tikz
\pic
\pic
\pic
\pic
\pic
\pic
[red]
[draw]
[draw=red]
[draw, shading=ball]
[fill=red!50]
{my
{my
{my
{my
{my
{my
pic};
pic};
pic};
pic};
pic};
pic};
\space
\space
\space
\space
\space
Code executed behind or in front of the path. As for nodes, a pic can be “behind” the current
path or “in front of it” and, just as for nodes, the two options behind path and in front of path
are used to specify which is meant. In detail, if node and pic are both used repeatedly on a path, in
the resulting picture we first see all nodes and pics with the behind path option set in the order they
appear on the path (nodes and pics are interchangeable in this regard), then comes the path, and then
come all nodes and pics that are in front of the path in the order they appeared.
253
\tikz \fill [fill=blue!20]
(1,1)
-- (2,2) pic [behind path]
-- (3,2) pic
-- (3,1) pic [rotate=30]
-- (2,1) pic [red, behind path]
{seagull}
{seagull}
{seagull}
{seagull};
In contrast to nodes, a pic need not only be completely behind the path or in front of the path as
specified by the user. Instead, a pic type may also specify that a certain part of the drawing should
always be behind the path and it may specify that a certain other part should always be before the
path. For this, the values of the following keys are relevant:
(no default)
/tikz/pics/foreground code=hcodei
This key stores hcodei that will always be drawn in front of the current path, even when
behind path is used. If behind path is not used and code is (also) set, the code of code is
drawn first, following by the foreground hcodei.
(no default)
/tikz/pics/background code=hcodei
Like foreground code, only that the hcodei is always put behind the path, never in front of it.
The foreach statement for pics. As for nodes, a pic specification may start with foreach. The
effect and semantics are the same as for nodes.
\tikz \pic foreach \x in {1,2,3} at (\x,0) {seagull};
Styles for pics. The following styles influence how nodes are rendered:
(style, initially empty)
/tikz/every pic
This style is installed at the beginning of every pic.
B
\begin{tikzpicture}[every node/.style={draw}]
\draw (0,0) node {A} -- (1,1) node {B};
\end{tikzpicture}
A
Name scopes. You can specify a hnamei for a pic using the key name=hnamei or by giving the name
in parenthesis inside the pic’s specification. The effect of this is, for once, quite different from what
happens for nodes: All that happens is that name prefix is set to hnamei at the beginning of the pic.
The name prefix key was already introduced in the description of the node command: It allows you
to set some text that is prefixed to all nodes in a scope. For pics this makes particular sense: All nodes
defined by a pic’s code can be referenced from outside the pic with the prefix provided.
To see how this works, let us add some nodes to the code of the seagull:
\tikzset{
seagull/.pic={
% Code for a "seagull". Do you see it?...
\coordinate (-left wing) at (-3mm,0);
\coordinate (-head)
at (0,0);
\coordinate (-right wing) at (3mm,0);
\draw (-left wing) to [bend left] (0,0) (-head) to [bend left] (-right wing);
}
}
Now, we can use it as follows:
\tikz {
\pic (Emma)
{seagull};
\pic (Alexandra) at (0,1) {seagull};
\draw (Emma-left wing) -- (Alexandra-right wing);
}
254
Sometimes, you may also wish your pic to access nodes outside the pic (typically, because they are given
as parameters). In this case, the name prefix gets in the way since the nodes outside the picture do not
have this prefix. The trick is to locally reset the name prefix to the value it had outside the picture,
which is achieved using the following style:
(no value)
/tikz/name prefix ..
This key is available only inside the code of a pic. There, it (locally) changes the name prefix to
the value it had outside the pic. This allows you to access nodes outside the current pic.
There are two general purpose keys that pics may find useful:
/tikz/pic text=htexti
(no default)
This macro stores the htexti in the macro \tikzpictext, which is \let to \relax by default. Setting
the pic text to some value is the “preferred” way of communicating a (single) piece of text that should
become part of a pic (typically of a node). In particular, the quotes library maps quoted parameters
to this key.
(no default)
/tikz/pic text options=hoptionsi
This macro stores the hoptionsi in the macro \tikzpictextoptions, which is \let to the empty string
by default. The quotes library maps options for quoted parameters to this key.
18.2.1
The Quotes Syntax
When you load the quotes library, you can use the “quotes syntax” inside the options of a pic. Recall that
for nodes this syntax is used to add a label to a node. For pics, the quotes syntax is used to set the pic text
key. Whether or not the pic type’s code takes this key into consideration is, however, up to the key.
In detail, when the quotes library is loaded, each time a key–value pair in a list of options passed to an
pic starts with ", the key–value pair must actually be a string of the following form:
"htexti"’hoptionsi
This string is transformed into the following:
every pic quotes/.try,pic text=htexti, pic text options={hoptionsi}
As example of a pic type that takes these values into account is the angle pic type:
α
\tikz \draw (3,0) coordinate (A)
-- (0,1) coordinate (B)
-- (1,2) coordinate (C)
pic [draw, "$\alpha$"] {angle};
As described in Section 17.10.4, the apostrophe becomes part of the hoptionsi, when present. As can be
seen above, the following style is executed:
(style, initially empty)
/tikz/every pic quotes
18.3
Defining New Pic Types
As explained in the description of the pic command, in order to define a new pic type you need to
1. define a key with the path prefix /tikz/pics that
2. sets the key /tikz/pics/code to the code of the pic.
It turns out that this is easy enough to achieve using styles:
\tikzset{
pics/seagull/.style ={
% Ok, this is the key that should, when
% executed, set the code key:
code = { %
\draw (...) ... ;
}
}
}
255
Even though the above pattern is easy enough, there is a special so-called key handler that allows us to
write even simpler code, namely:
\tikzset{
seagull/.pic = {
\draw (...) ... ;
}
}
Key handler hkeyi/.pic=hsome codei
This handler can only be used with a key with the prefix /tikz/, so just should normally use it only as
an option to a Tik Z command or to the \tikzset command. It takes the hkeyi’s path and, inside that
path, it replaces /tikz/ by /tikz/pics/ (so, basically, it adds the “missing” pics part of the path).
Then, it sets up things so that the resulting name to key is a style that executes code=some code.
In almost all cases, the .pic key handler will suffice to setup keys. However, there are cases where you
really need to use the first version using .style and code=:
• Whenever your pic type needs to set the foreground or the background code.
• In case of complicated arguments given to the keys.
As an example, let us define a simple pic that draws a filled circle behind the path. Furthermore, we
make the circle’s radius a parameter of the pic:
\tikzset{
pics/my circle/.style = {
background code = { \fill circle [radius=#1]; }
}
}
\tikz [fill=blue!30]
\draw (0,0) pic {my circle=2mm} -- (1,1) pic {my circle=5mm};
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19
19.1
Specifying Graphs
Overview
Tik Z offers a powerful path command for specifying how the nodes in a graph are connected by edges and
arcs: The graph path command, which becomes available when you load the graphs library.
Tik Z Library graphs
\usetikzlibrary{graphs} % LATEX and plain TEX
\usetikzlibrary[graphs] % ConTEXt
The package must be loaded to use the graph path command.
In this section, by graph we refer to a set of nodes together with some edges (sometimes also called arcs,
in case they are directed) such as the following:
a
d
\tikz \graph { a -> {b, c} -> d };
a
1
\tikz \graph {
subgraph I_nm [V={a, b, c}, W={1,...,4}];
b
2
a -> { 1, 2, 3 };
b -> { 1, 4 };
c -> { 2 [>green!75!black], 3, 4 [>red]}
c
3
b
c
};
4
\tikz
\graph [nodes={draw, circle}, clockwise, radius=.5cm, empty nodes, n=5] {
subgraph I_n [name=inner] --[complete bipartite]
subgraph I_n [name=outer]
};
\tikz
\graph [nodes={draw, circle}, clockwise, radius=.75cm, empty nodes, n=8] {
subgraph C_n [name=inner] <->[shorten <=1pt, shorten >=1pt]
subgraph C_n [name=outer]
};
257
a
n
f
g
n
g
f
a
a
n
g
a
n
n
\tikz [>={To[sep]}, rotate=90, xscale=-1,
mark/.style={fill=black!50}, mark/.default=]
\graph [trie, simple,
nodes={circle,draw},
edges={nodes={
inner sep=1pt, anchor=mid,
fill=graphicbackground}}, % yellowish background
put node text on incoming edges]
{
root[mark] -> {
a -> n -> {
g [mark],
f -> a -> n -> g [mark]
},
f -> a -> n -> g [mark],
g[mark],
n -> {
g[mark],
f -> a -> n -> g[mark]
}
},
{ [edges=red] % highlight one path
root -> f -> a -> n
}
};
g
g
f
g
The nodes of a graph are normal Tik Z nodes, the edges are normal lines drawn between nodes. There is
nothing in the graph library that you cannot do using the normal \node and the edge commands. Rather,
its purpose is to offer a concise and powerful way of specifying which nodes are present and how they are
connected. The graph library only offers simple methods for specifying where the nodes should be shown, its
main strength is in specifying which nodes and edges are present in principle. The problem of finding “good
positions on the canvas” for the nodes of a graph is left to graph drawing algorithms, which are covered in
Part IV of this manual and which are not part of the graphs library; indeed, these algorithms can be used
also with graphs specified using node and edge commands. As an example, consider the above drawing of
a trie, which is drawn without using the graph drawing libraries. Its layout can be somewhat improved by
loading the layered graph drawing library, saying \tikz[layered layout,..., and then using LuaTEX,
resulting in the following drawing of the same graph:
a
f
g
n
n
g
f
a
a
n
g
a
n
g
f
n
g
g
The graph library uses a syntax that is quite different from the normal Tik Z syntax for specifying nodes.
The reason for this is that for many medium-sized graphs it can become quite cumbersome to specify all the
nodes using \node repeatedly and then using a great number of edge command; possibly with complicated
\foreach statements. Instead, the syntax of the graph library is loosely inspired by the dot format, which
is quite useful for specifying medium-sized graphs, with some extensions on top.
19.2
Concepts
The present section aims at giving a quick overview of the main concepts behind the graph command. The
exact syntax is explained in more detail in later sections.
19.2.1
Concept: Node Chains
The basic way of specifying a graph is to write down a node chain as in the following example:
foo
bar
blub
\tikz [every node/.style = draw]
\graph { foo -> bar -> blub };
258
As can be seen, the text foo -> bar -> my node creates three nodes, one with the text foo, one with
bar and one with the text blub. These nodes are connected by arrows, which are caused by the -> between
the node texts. Such a sequence of node texts and arrows between them is called a chain in the following.
Inside a graph there can be more than one chain:
a
b
c
d
e
f
\tikz \graph {
a -> b -> c;
d -> e -> f;
g -> f;
};
g
Multiple chains are separated by a semicolon or a comma (both have exactly the same effect). As the
example shows, when a node text is seen for the second time, instead of creating a new node, a connection
is created to the already existing node.
When a node like f is created, both the node name and the node text are identical by default. This is
not always desirable and can be changed by using the as key or by providing another text after a slash:
x1
x3 , x 4
x2
\tikz \graph {
x1/$x_1$ -> x2 [as=$x_2$, red] -> x34/{$x_3,x_4$};
x1 -> [bend left] x34;
};
When you wish to use a node name that contains special symbols like commas or dashes, you must
surround the node name by quotes. This allows you to use quite arbitrary text as a “node name”:
x1
19.2.2
x3 , x 4
x2
\tikz \graph {
"$x_1$" -> "$x_2$"[red] -> "$x_3,x_4$";
"$x_1$" ->[bend left] "$x_3,x_4$";
};
Concept: Chain Groups
Multiple chains that are separated by a semicolon or a comma and that are surrounded by curly braces form
what will be called a chain group or just a group. A group in itself has no special effect. However, things
get interesting when you write down a node or even a whole group and connect it to another group. In this
case, the “exit points” of the first node or group get connected to the “entry points” of the second node or
group:
a
b
c
d
e
f
\tikz \graph {
a -> {
b -> c,
d -> e
} -> f
};
Chain groups make it easy to create tree structures:
root
child 1
child 2
grand child 1
child 3
grand child 2
grand child 3
\tikz
\graph [grow down,
branch right=2.5cm] {
root -> {
child 1,
child 2 -> {
grand child 1,
grand child 2
},
child 3 -> {
grand child 3
}
}
};
As can be seen, the placement is not particularly nice by default, use the algorithms from the graph
drawing libraries to get a better layout. For instance, adding tree layout to the above code results in the
following somewhat more pleasing rendering:
259
root
child 1
child 2
grand child 1
19.2.3
child 3
grand child 2
grand child 3
Concept: Edge Labels and Styles
When connectors like -> or -- are used to connect nodes or whole chain groups, one or more edges will
typically be created. These edges can be styles easily by providing options in square brackets directly after
these connectors:
a
c
b
\tikz \graph {
a ->[red] b --[thick] {c, d};
};
d
Using the quotes syntax, see Section 17.10.4, you can even add labels to the edges easily by putting the
labels in quotes:
a
foo
b
bar
c
bar
\tikz \graph {
a ->[red, "foo"] b --[thick, "bar"] {c, d};
};
d
For the first edge, the effect is as desired, however between b and the group {c,d} two edges are inserted
and the options thick and the label option "bar" is applied to both of them. While this is the correct and
consistent behaviour, we typically might wish to specify different labels for the edge going from b to c and
the edge going from b to d. To achieve this effect, we can no longer specify the label as part of the options
of --. Rather, we must pass the desired label to the nodes c and d, but we must somehow also indicate that
these options actually “belong” to the edge “leading to” to nodes. This is achieved by preceding the options
with a greater-than sign:
a
b
foo
bar
c
\tikz \graph {
a -> b -- {c [> "foo"], d [> "bar"’]};
};
d
Symmetrically, preceding the options by < causes the options and labels to apply to the “outgoing” edges
of the node:
a
b
bar
c
\tikz \graph {
a [< red] -> b -- {c [> blue], d [> "bar"’]};
};
d
This syntax allows you to easily create trees with special edge labels as in the following example of a
treap:
9
h
4
c
7
2 0
a
e
j
\tikz
\graph [edge quotes={fill=white,inner sep=1pt},
grow down, branch right, nodes={circle,draw}] {
"" -> h [>"9"] -> {
c [>"4"] -> {
a [>"2"],
e [>"0"]
},
j [>"7"]
}
};
260
19.2.4
Concept: Node Sets
When you write down some node text inside a graph command, a new node is created by default unless this
node has already been created inside the same graph command. In particular, if a node has already been
declared outside of the current graph command, a new node of the same name gets created.
This is not always the desired behaviour. Often, you may wish to make nodes part of a graph than have
already been defined prior to the use of the graph command. For this, simply surround a node name by
parentheses. This will cause a reference to be created to an already existing node:
A
B
C
\tikz {
\node (a) at (0,0) {A};
\node (b) at (1,0) {B};
\node (c) at (2,0) {C};
\graph { (a) -> (b) -> (c) };
}
You can even go a step further: A whole collection of nodes can all be flagged to belong to a node set by
adding the option set=hnode set namei. Then, inside a graph command, you can collectively refer to these
nodes by surrounding the node set name in parentheses:
\tikz [new set=my nodes] {
\node [set=my nodes, circle,
\node [set=my nodes, rectangle,
\node [set=my nodes, diamond,
\node (d)
[star,
A
X
B
D
at
at
at
at
(1,1)
(1.5,0)
(1,-1)
(3,0)
{A};
{B};
{C};
{D};
\graph { X -> (my nodes) -> (d) };
C
19.2.5
draw]
draw]
draw]
draw]
}
Concept: Graph Macros
Often, a graph will consist – at least in parts – of standard parts. For instance, a graph might contain a
cycle of certain size or a path or a clique. To facilitate specifying such graphs, you can define a graph macro.
Once a graph macro has been defined, you can use the name of the graph to make a copy of the graph part
of the graph currently being specified:
\tikz \graph { subgraph K_n [n=6, clockwise] };
1
6
2
5
3
4
\tikz \graph { subgraph C_n [n=5, clockwise] -> mid };
1
5
2
mid
4
3
The library graphs.standard defines a number of such graphs, including the complete clique Kn on n
nodes, the complete bipartite graph Kn,m with shores sized n and m, the cycle Cn on n nodes, the path Pn
on n nodes, and the independent set In on n nodes.
19.2.6
Concept: Graph Expressions and Color Classes
When a graph is being constructed using the graph command, it is constructed recursively by uniting smaller
graphs to larger graphs. During this recursive union process the nodes of the graph get implicitly colored
(conceptually) and you can also explicitly assign colors to individual nodes and even change the colors as
the graph is being specified. All nodes having the same color form what is called a color class.
The power of color class is that special connector operators allow you to add edges between nodes
having certain colors. For instance, saying clique=red at the beginning of a group will cause all nodes
261
that have been flagged as being (conceptually) “red” to be connected as a clique. Similarly, saying
complete bipartite={red}{green} will cause edges to be added between all red and all green nodes.
More advanced connectors, like the butterfly connector, allow you to add edges between color classes in a
fancy manner.
\tikz [x=8mm, y=6mm, circle]
\graph [nodes={fill=blue!70}, empty nodes, n=8] {
subgraph I_n [name=A] --[butterfly={level=4}]
subgraph I_n [name=B] --[butterfly={level=2}]
subgraph I_n [name=C] --[butterfly]
subgraph I_n [name=D] -subgraph I_n [name=E]
};
19.3
Syntax of the Graph Path Command
19.3.1
The Graph Command
In order to construct a graph, you should use the graph path command, which can be used anywhere on a
path at any place where you could also use a command like, say, plot or --.
\graph
Inside a {tikzpicture} this is an abbreviation for \path graph.
\path . . . graph[hoptionsi]hgroup specificationi . . . ;
When this command is encountered on a path, the construction of the current path is suspended
(similarly to an edge command or a node command). In a local scope, the hoptionsi are first executed
with the key path /tikz/graphs using the following command:
\tikzgraphsset{hoptionsi}
Executes the hoptionsi with the path prefix /tikz/graphs.
Apart from the keys explained in the following, further permissible keys will be listed during the course
of the rest of this section.
(style, no value)
/tikz/graphs/every graph
This style is executed at the beginning of every graph path command prior to the hoptionsi.
Once the scope has been set up and once the hoptionsi have been executed, a parser starts to parse
the hgroup specificationi. The exact syntax of such a group specification in explained in detail in
Section 19.3.2. Basically, a group specification is a list of chain specifications, separated by commas or
semicolons.
Depending on the content of the hgroup specificationi, two things will happen:
1. A number of new nodes may be created. These will be inserted into the picture in the same order
as if they had been created using multiple node path commands at the place where the graph path
command was used. In other words, all nodes created in a graph path command will be painted
on top of any nodes created earlier in the path and behind any nodes created later in the path.
Like normal nodes, the newly created nodes always lie on top of the path that is currently being
created (which is often empty, for instance when the \graph command is used).
2. Edges between the nodes may be added. They are added in the same order as if the edge command
had been used at the position where the graph command is being used.
Let us now have a look at some common keys that may be used inside the hoptionsi:
(no default)
/tikz/graphs/nodes=hoptionsi
262
This option causes the hoptionsi to be applied to each newly created node inside the hgroup
specificationi.
a
c
b
\tikz \graph [nodes=red] { a -> b -> c };
Multiple uses of this key accumulate.
(no default)
/tikz/graphs/edges=hoptionsi
This option causes the hoptionsi to be applied to each newly created edge inside the hgroup
specificationi.
a
c
b
\tikz \graph [edges={red,thick}] { a -> b -> c };
Again, multiple uses of this key accumulate.
(no default)
/tikz/graphs/edge=hoptionsi
This is an alias for edges.
/tikz/graphs/edge node=hnode specificationi
(no default)
This key specifies that the hnode specificationi should be added to each newly created edge as an
implicitly placed node.
a
Xc
Xb
\tikz \graph [edge node={node [red, near end] {X}}] { a -> b -> c };
Again, multiple uses of this key accumulate.
a YX b YX c
\tikz \graph [edge node={node [near end] {X}},
edge node={node [near start] {Y}}] { a -> b -> c };
(no default)
/tikz/graphs/edge label=htexti
This key is an abbreviation for edge node=node[auto]{htexti}. The net effect is that the text is
placed next to the newly created edges.
a
x
x
b
x
c
\tikz \graph [edge label=x] { a -> b -> {c,d} };
d
(no default)
/tikz/graphs/edge label’=htexti
This key is an abbreviation for edge node=node[auto],swap]{htexti}.
out
1
5
in in
\tikz \graph [edge label=out, edge label’=in]
{ subgraph C_n [clockwise, n=5] };
2
in
in
4
out
in
3
out
out
19.3.2
out
Syntax of Group Specifications
A hgroup specificationi inside a graph path command has the following syntax:
{[hoptionsi]hlist of chain specificationsi}
263
The hchain specificationsi must contain chain specifications, whose syntax is detailed in the next section,
separated by either commas or semicolons; you can freely mix them. It is permissible to use empty lines
(which are mapped to \par commands internally) to structure the chains visually, they are simply ignored
by the parser.
In the following example, the group specification consists of three chain specifications, namely of a ->
b, then c alone, and finally d -> e -> f:
a
\tikz \graph {
a -> b,
c;
b
c
d -> e -> f
};
d
e
f
The above has the same effect as the more compact group specification {a->b,c,d->e->f}.
Commas are used to detect where chain specifications end. However, you will often wish to use a comma
also inside the options of a single node like in the following example:
a
b
c
\tikz \graph {
a [red, draw] -> b [blue, draw],
c [brown, draw, circle]
};
Note that the above example works as expected: The first comma inside the option list of a is not
interpreted as the end of the chain specification “a [red”. Rather, commas inside square brackets are
“protected” against being interpreted as separators of group specifications.
The hoptionsi that can be given at the beginning of a group specification are local to the group. They
are executed with the path prefix /tikz/graphs. Note that for the outermost group specification of a graph
it makes no difference whether the options are passed to the graph command or whether they are given at
the beginning of this group. However, for groups nested inside other groups, it does make a difference:
a
b
d
c
\tikz \graph {
a -> { [nodes=red] % the option is local to these nodes:
b, c
} ->
d
};
Using foreach. There is special support for the \foreach statement inside groups: You may use the
statement inside a group specification at any place where a hchain specificationi would normally go. In
this case, the \foreach statement is executed and for each iteration the content of the statement’s body is
treated and parsed as a new chain specification.
a
a1
a2
a3
x1
y1
x2
y2
x3
y3
\tikz \graph [math nodes, branch down=5mm] {
a -> {
\foreach \i in {1,2,3} {
a_\i -> { x_\i, y_\i }
},
b
}
};
b
Using macros. In some cases you may wish to use macros and TEX code to compute which nodes and
edges are present in a group. You cannot use macros in the normal way inside a graph specification since
the parser does not expand macros as it scans for the start and end of groups and node names. Rather, only
after commas, semicolons, and hyphens have already been detected and only after all other parsing decisions
have been made will macros be expanded. At this point, when a macro expands to, say a,b, this will not
result in two nodes to be created since the parsing is already done. For these reasons, a special key is needed
to make it possible to “compute” which nodes should be present in a group.
264
(no default)
/tikz/graph/parse=htexti
This key can only be used inside the hoptionsi of a hgroup specificationi. Its effect is that the htexti is
inserted at the beginning of the current group as if you had entered it there. Naturally, it makes little
sense to just write down some static htexti since you could just as well directly place it at the beginning
of the group. The real power of this command stems from the fact that the keys mechanism allows you
to say, for instance, parse/.expand once to insert the text stored in some macro into the group.
a
b
d
e
c
\def\mychain{ a -> b -> c; }
\tikz \graph { [parse/.expand once=\mychain] d -> e };
In the following, more fancy example we use a loop to create a chain of dynamic length.
1
2
3
4
\def\mychain#1{
\def\mytext{1}
\foreach \i in {2,...,#1} {
\xdef\mytext{\mytext -> \i}
}
}
\tikzgraphsset{my chain/.style={
/utils/exec=\mychain{#1},
parse/.expand once=\mytext}
}
\tikz \graph { [my chain=4] };
Multiple uses of this key accumulate, that is, all the texts given in the different uses is inserted in the
order it is given.
19.3.3
Syntax of Chain Specifications
A hchain specificationi has the following syntax: It consists of a sequence of hnode specificationsi, where
subsequent node specifications are separated by hedge specificationsi. Node specifications, which typically
consist of some text, are discussed in the next section in more detail. They normally represent a single node
that is either newly created or exists already, but they may also specify a whole set of nodes.
An hedge specificationi specifies which of the node(s) to the left of the edge specification should be
connected to which node(s) to the right of it and it also specifies in which direction the connections go. In
the following, we only discuss how the direction is chosen, the powerful mechanism behind choosing which
nodes should be connect is detailed in Section 19.7.
The syntax of an edge specification is always one of the following five possibilities:
-> [hoptionsi]
-- [hoptionsi]
<- [hoptionsi]
<-> [hoptionsi]
-!- [hoptionsi]
The first four correspond to a directed edge, an undirected edge, a “backward” directed edge, and a
bidirected edge, respectively. The fifth edge specification means that there should be no edge (this specification can be used together with the simple option to remove edges that have previously been added, see
Section 19.5).
Suppose the nodes hleft nodesi are to the left of the hedge specificationi and hright nodesi are to the right
and suppose we have written -> between them. Then the following happens:
1. The hoptionsi are executed (inside a local scope) with the path /tikz/graphs. These options may
setup the connector algorithm (see below) and may also use keys like edge or edge label to specify
how the edge should look like. As a convenience, whenever an unknown key is encountered for the
path /tikz/graphs, the key is passed to the edge key. This means that you can directly use options
like thick or red inside the hoptionsi and they will apply to the edge as expected.
2. The chosen connector algorithm, see Section 19.7, is used to compute from which of the hleft nodesi
an edge should lead to which of the hright nodesi. Suppose that (l1 , r1 ), . . . , (ln , rn ) is the list of node
pairs that result (so there should be an edge between l1 and r1 and another edge between l2 and r2
and so on).
265
3. For each pair (li , ri ) an edge is created. This is done by calling the following key (for the edge
specification ->, other keys are executed for the other kinds of specifications):
/tikz/graphs/new ->={hleft nodei}{hright nodei}{hedge optionsi}{hedge nodesi}
(no default)
This key will be called for a -> edge specification with the following four parameters:
(a) hleft nodei is the name of the “left” node, that is, the name of li .
(b) hright nodei is the name of the right node.
(c) hedge optionsi are the accumulated options from all calls of /tikz/graph/edges in groups
that surround the edge specification.
(d) hedge nodesi is text like node {A} node {B} that specifies some nodes that should be put as
labels on the edge using Tik Z’s implicit positioning mechanism.
By default, the key executes the following code:
\path [->,every new ->]
(hleft nodei\tikzgraphleftanchor) edge [hedge optionsi] hedge nodesi
(hright nodei\tikzgraphrightanchor);
You are welcome to change the code underlying the key.
(style, no value)
/tikz/every new ->
This key gets executed by default for a new ->.
/tikz/graphs/left anchor=hanchor i
(no default)
This anchor is used for the node that is to the left of an edge specification. Setting this anchor
to the empty string means that no special anchor is used (which is the default). The hanchor i is
stored in the macro \tikzgraphleftanchor with a leading dot.
a
e
b
f
c
g
a
e
b
f
c
g
\tikz \graph {
{a,b,c} -> [complete bipartite] {e,f,g}
};
\tikz \graph [left anchor=east, right anchor=west] {
{a,b,c} -- [complete bipartite] {e,f,g}
};
/tikz/graphs/right anchor=hanchor i
(no default)
Works like left anchor, only for \tikzgraphrightanchor.
For the other three kinds of edge specifications, the following keys will be called:
/tikz/graphs/new –={hleft nodei}{hright nodei}{hedge optionsi}{hedge nodesi}
(no default)
This key is called for -- with the same parameters as above. The only difference in the definition
is that in the \path command the -> gets replaced by -.
(style, no value)
/tikz/every new –
/tikz/graphs/new <->={hleft nodei}{hright nodei}{hedge optionsi}{hedge nodesi}
(no default)
Called for <-> with the same parameters as above. The -> is replaced by <(style, no value)
/tikz/every new <->
266
/tikz/graphs/new <-={hleft nodei}{hright nodei}{hedge optionsi}{hedge nodesi}
(no default)
Called for <- with the same parameters as above.4
(style, no value)
/tikz/every new b;
c -- d;
e <- f;
g <-> h;
i -!- j;
};
Syntax of Node Specifications
Node specifications are the basic building blocks of a graph specification. There are three different possible
kinds of node specifications, each of which has a different syntax:
Direct Node Specification
"hnode namei"/"htexti" [hoptionsi]
(note that the quotation marks are optional and only needed when the hnode namei contains special
symbols)
Reference Node Specification
(hnode name or node set namei)
Group Node Specification
hgroup specificationi
The rule for determining which of the possible kinds is meant is as follows: If the node specification starts
with an opening parenthesis, a reference node specification is meant; if it starts with an opening curly brace,
a group specification is meant; and in all other cases a direct node specification is meant.
Direct Node Specifications. If after reading the first symbol of a node specification is has been
detected to be direct, Tik Z will collect all text up to the next edge specification and store it as the hnode
namei; however, square brackets are used to indicate options and a slash ends the hnode namei and start a
special htexti that is used as a rendering text instead of the original hnode namei.
Due to the way the parsing works and due to the restrictions on node names, most special characters
are forbidding inside the hnode namei, including commas, semicolons, hyphens, braces, dots, parentheses,
slashes, dashes, and more (but spaces, single underscores, and the hat character are allowed). To use
special characters in the name of a node, you can optionally surround the hnode namei and/or the htexti
by quotation marks. In this case, you can use all of the special symbols once more. The details of what
happens, exactly, when the hnode namei is surrounded by quotation marks is explained later; surrounding
the htexti by quotation marks has essentially the same effect as surrounding it by curly braces.
Once the node name has been determined, it is checked whether the same node name was already used
inside the current graph. If this is the case, then we say that the already existing node is referenced ; otherwise
we say that the node is fresh.
a
c
b
\tikz \graph {
a -> b; % both are fresh
c -> a; % only c is fresh, a is referenced
};
This behaviour of deciding whether a node is fresh or referenced can, however, be modified by using the
following keys:
4 You might wonder why this key is needed: It seems more logical at first sight to just call newedgedirected with swapped
first parameters. However, a positioning algorithm might wish to take the fact into account that an edge is “backward” rather
than “forward” in order to improve the layout. Also, different arrow heads might be used.
267
/tikz/graphs/use existing node=htrue or falsei
(default true)
When this key is set to true, all nodes will be considered to the referenced, no node will be fresh. This
option is useful if you have already created all the nodes of a graph prior to using the graph command
and you now only wish to connect the nodes.
/tikz/graphs/fresh nodes=htrue or falsei
(default true)
When this key is set to true, all nodes will be considered to be fresh. This option is useful when you
create for instance a tree with many identical nodes.
When a node name is encountered that was already used previously, a new name is chosen is follows:
An apostrophe (’) is appended repeatedly until a node name is found that has not yet been used:
a
b
b
b
c
c
c
c
c
c
\tikz \graph [branch down=5mm] {
{ [fresh nodes]
a -> {
b -> {c, c},
b -> {c, c},
b -> {c, c},
}
},
b’ -- b”
};
/tikz/graphs/number nodes=hstart number i
(default 1)
When this key is used in a scope, each encountered node name will get appended a new number, starting
with hstarti. Typically, this ensures that all node names are different. Between the original node name
and the appended number, the setting of the following will be inserted:
(no default, initially space)
/tikz/graphs/number nodes sep=htexti
a
b
b
b
c
c
c
c
c
c
\tikz \graph [branch down=5mm] {
{ [number nodes]
a -> {
b -> {c, c},
b -> {c, c},
b -> {c, c},
}
},
b 2 -- b 5
};
When a fresh node has been detected, a new node is created in the inside a protecting scope. For this, the
current placement strategy is asked to compute a default position for the node, see Section 19.9 for details.
Then, the command
\node (hfull node namei) [hnode optionsi] {htexti};
is called. The different parameters are as follows:
• The hfull node namei is normally the hnode namei that has been determined as described before.
However, there are two exceptions:
First, if the hnode namei is empty (which happens when there is no hnode namei before the slash),
then a fresh internal node name is created and used as hfull node namei. This name is guaranteed to
be different from all node names used in this or any other graph. Thus, a direct node starting with a
slash represents an anonymous fresh node.
Second, you can use the following key to prefix the hnode namei inside the hfull node namei:
(no default)
/tikz/graphs/name=htexti
This key prepends the htexti, followed by a separating symbol (a space by default), to all hnode
nameis inside a hfull node namei. Repeated calls of this key accumulate, leading to ever-longer
“name paths”:
268
1
1
2
2
3
3
\begin{tikzpicture}
\graph {
{ [name=first] 1, 2, 3} -{ [name=second] 1, 2, 3}
};
\draw [red] (second 1) circle [radius=3mm];
\end{tikzpicture}
Note that, indeed, in the above example six nodes are created even though the first and second
set of nodes have the same hnode namei. The reason is that the full names of the six nodes are all
different. Also note that only the hnode namei is used as the node text, not the full name. This
can be changed as described later on.
This key can be used repeatedly, leading to ever longer node names.
(no default, initially \space)
/tikz/graphs/name separator=hsymbolsi
Changes the symbol that is used to separate the htexti from the hnode namei. The default is
\space, resulting in a space.
1
1
2
2
3
3
1
1
2
2
3
3
\begin{tikzpicture}
\graph [name separator=] { % no separator
{ [name=first] 1, 2, 3} -{ [name=second] 1, 2, 3}
};
\draw [red] (second1) circle [radius=3mm];
\end{tikzpicture}
\begin{tikzpicture}
\graph [name separator=-] {
{ [name=first] 1, 2, 3} -{ [name=second] 1, 2, 3}
};
\draw [red] (second-1) circle [radius=3mm];
\end{tikzpicture}
• The hnode optionsi are
1. The options that have accumulated in calls to nodes from the surrounding scopes.
2. The local hoptionsi.
The options are executed with the path prefix /tikz/graphs, but any unknown key is executed with
the prefix /tikz. This means, in essence, that some esoteric keys are more difficult to use inside the
options and that any key with the prefix /tikz/graphs will take precedence over a key with the prefix
/tikz.
• The htexti that is passed to the \node command is computed as follows: First, you can use the following
key to directly set the htexti:
(no default)
/tikz/graphs/as=htexti
The htexti is used as the text of the node. This allows you to provide a text for the node that
differs arbitrarily from the name of the node.
x
y5
a–b
\tikz \graph { a [as=$x$] -- b [as=$y_5$] -> c [red, as={a--b}] };
This key always takes precedence over all of the mechanisms described below.
In case the as key is not used, a default text is chosen as follows: First, when a direct node specification
contains a slash (or, for historical reasons, a double underscore), the text to the right of the slash (or
double underscore) is stored in the macro \tikzgraphnodetext; if there is no slash, the hnode namei
is stored in \tikzgraphnodetext, instead. Then, the current value of the following key is used as
htexti:
269
(no default)
/tikz/graphs/typeset=hcodei
The macro or code stored in this key is used as the htexti if the node. Inside the hcodei, the
following macros are available:
\tikzgraphnodetext
This macro expands to the htexti to the right of the double underscore or slash in a direct
node specification or, if there is no slash, to the hnode namei.
\tikzgraphnodename
This macro expands to the name of the current node with the path.
\tikzgraphnodepath
This macro expands to the current path of the node. These paths result from the use of the
name key as described above.
\tikzgraphnodefullname
This macro contains the concatenation of the above two.
By default, the typesetter is just set to \tikzgraphnodetext, which means that the default text of a
node is its name. However, it may be useful to change this: For instance, you might wish that the text
of all graph nodes is, say, surrounded by parentheses:
(a)
(b)
(c)
\tikz \graph [typeset=(\tikzgraphnodetext)]
{ a -> b -> c };
A more advanced macro might take apart the node text and render it differently:
a1,...,n
b2,...,m
\def\mytypesetter{\expandafter\myparser\tikzgraphnodetext\relax}
\def\myparser#1 #2 #3\relax{%
$#1_{#2,\dots,#3}$
}
\tikz \graph [typeset=\mytypesetter, grow down]
{ a 1 n -> b 2 m -> c 4 nm };
c4,...,nm
The following styles install useful predefined typesetting macros:
(no value)
/tikz/graphs/empty nodes
Just sets typeset to nothing, which causes all nodes to have an empty text (unless, of course, the
as option is used):
\tikz \graph [empty nodes, nodes={circle, draw}] { a -> {b, c} };
(no value)
/tikz/graphs/math nodes
Sets typeset to $\tikzgraphnodetext$, which causes all nodes names to be typeset in math
mode:
a1
b2
\tikz \graph [math nodes, nodes={circle, draw}] { a_1 -> {b^2, c_3^n} };
cn3
If a node is referenced instead of fresh, then this node becomes the node that will be connected by the
preceding or following edge specification to other nodes. The hoptionsi are executed even for a referenced
node, but they cannot be used to change the appearance of the node (because the node exists already).
Rather, the hoptionsi can only be used to change the logical coloring of the node, see Section 19.7 for details.
270
Quoted Node Names. When the hnode namei and/or the htexti of a node is surrounded by quotation
marks, you can use all sorts of special symbols as part of the text that are normally forbidden:
’s
It
t!
an
rt
po
im
Hi, World!
actual text
\begin{tikzpicture}
\graph [grow right=2cm] {
"Hi, World!"
-> "It’s \emph{important}!"[red,rotate=-45];
"name"/actual text -> "It’s \emph{important}!";
};
\draw (name) circle [radius=3pt];
\end{tikzpicture}
In detail, for the following happens when qutation marks are encountered at the beginning of a node
name or its text:
• Everything following the quotation mark up to the next single quotation mark is collected into a
macro hcollected i. All sorts of special characters, including commas, square brackets, dashes, and even
backslashes are allowed here. Basically, the only restriction is that braces must be balanced.
• A double quotation mark ("") does not count as the “next single quotation mark.” Rather, it is
replaced by a single quotation mark. For instance, "He said, ""Hello world.""" would be stored
inside hcollected i as He said, "Hello world." However, this rule applies only on the outer-most level
of braces. Thus, in
"He {said, ""Hello world.""}"
we would get He {said, ""Hello world.""} as hcollected i.
• “The next single quotation mark” refers to the next quotation mark on the current level of braces, so
in "hello {"} world", the next quotation mark would be the one following world.
Now, once the hcollected i text has been gather, it is used as follows: When used as htexti (what is actually
displayed), it is just used “as is”. When it is used as hnode namei, however, the following happens: Every
“special character” in hcollected i is replaced by its Unicode name, surrounded by @-signs. For instance, if
hcollected i is Hello, world!, the hnode namei is the somewhat longer text Hello@COMMA@ world@EXCLAMATION MARK@. Admittedly, referencing such a node from outside the graph is cumbersome, but when you
use exactly the same hcollected i text once more, the same hnode namei will result. The following characters
are considered “special”:
|$&^~_[](){}/.-,+*’‘!":;<=>?@#%\{}
These are exactly the Unicode character with a decimal code number between 33 and 126 that are neither
digits nor letters.
Reference Node Specifications. A reference node specification is a node specification that starts with
an opening parenthesis. In this case, parentheses must surround a hnamei as in (foo), where foo is the
hnamei. The following will now happen:
1. It is tested whether hnamei is the name of a currently active node set. This case will be discussed in
a moment.
2. Otherwise, the hnamei is interpreted and treated as a referenced node, but independently of whether
the node has already been fresh in the current graph or not. In other words, the node must have been
defined either already inside the graph (in which case the parenthesis are more or less superfluous) or
it must have been defined outside the current picture.
The way the referenced node is handled is the same way as for a direct node that is a referenced node.
If the node does not already exist, an error message is printed.
Let us now have a look at node sets. Inside a {tikzpicture} you can locally define a node set by using
the following key:
/tikz/new set=hset namei
(no default)
This will setup a node set named hset namei within the current scope. Inside the scope, you can add
nodes to the node set using the set key. If a node set of the same name already exists in the current
scope, it will be reset and made empty for the current scope.
Note that this command has the path /tikz and is normally used outside the graph command.
271
/tikz/set=hset namei
(no default)
This key can be used as an option with a node command. The hset namei must be the name of a node
set that has previously been created inside some enclosing scope via the new set key. The effect is that
the current node is added to the node set.
When you use a graph command inside a scope where some node set called hset namei is defined, then
inside this graph command you use (hset namei) to reference all of the nodes in the node set. The effect
is the same as if instead of the reference to the set name you had created a group specification containing a
list of references to all the nodes that are part of the node set.
g1
g2
g3
r1
r2
r3
root
\begin{tikzpicture}[new set=red, new set=green, shorten >=2pt]
\foreach \i in {1,2,3} {
\node [draw, red!80,
set=red]
(r\i) at (\i,1) {$r_\i$};
\node [draw, green!50!black, set=green] (g\i) at (\i,2) {$g_\i$};
}
\graph {
root [xshift=2cm] ->
(red)
-> [complete bipartite, right anchor=south]
(green)
};
\end{tikzpicture}
There is an interesting caveat with referencing node sets: Suppose that at the beginning of a graph you
just say (foo); where foo is a set name. Unless you have specified special options, this will cause the
following to happen: A group is created whose members are all the nodes of the node set foo. These nodes
become referenced nodes, but otherwise nothing happens since, by default, the nodes of a group are not
connected automatically. However, the referenced nodes have now been referenced inside the graph, you can
thus subsequently access them as if they had been defined inside the graph. Here is an example showing how
you can create nodes outside a graph command and then connect them inside as if they had been declared
inside:
a
b
c
e
d
\begin{tikzpicture}[new set=import nodes]
\begin{scope}[nodes={set=import nodes}] % make all nodes part of this set
\node [red] (a) at (0,1) {$a$};
\node [red] (b) at (1,1) {$b$};
\node [red] (d) at (2,1) {$d$};
\end{scope}
\graph {
(import nodes);
% "import" the nodes
a -> b -> c -> d -> e;
};
\end{tikzpicture}
% only c and e are new
Group Node Specifications. At a place where a node specification should go, you can also instead
provide a group specification. Since nodes specifications are part of chain specifications, which in turn are
part of group specifications, this is a recursive definition.
a
b
e
\tikz \graph { a -> {b,c,d} -> {e -> {f,g}, h} };
g
c
d
f
h
As can be seen in the above example, when two groups of nodes are connected via an edge specification,
it is not immediately obvious which connecting edges are added. This is detailed in Section 19.7.
19.3.5
Specifying Tries
In computer science, a trie is a special kind of tree, where for each node and each symbol of an alphabet,
there is at most one child of the node labeled with this symbol.
The trie key is useful for drawing tries, but it can also be used in other situations. What it does,
essentially, is to prepend the node names of all nodes before the current node of the current chain to the
272
node’s name. This will often make it easier or more natural to specify graphs in which several nodes have
the same label.
/tikz/graphs/trie=htrue or falsei
(default true, initially false)
If this key is set to true, after a node has been created on a chain, the name key is executed with the
node’s hnode namei. Thus, all nodes later on this chain have the “path” of nodes leading to this node
as their name. This means, in particular, that
1. two nodes of the same name but in different parts of a chain will be different,
2. while if another chain starts with the same nodes, no new nodes get created.
In total, this is exactly the behaviour you would expect of a trie:
a
a
c
a
b
\tikz \graph [trie] {
a -> {
a,
c -> {a, b},
b
}
};
b
You can even “reiterate” over a path in conjunction with the simple option. However, in this case,
the default placement strategies will not work and you will need options like layered layout from the
graph drawing libraries, which need LuaTEX.
a
b
a
d
a
\tikz \graph [trie, simple, layered layout] {
a -> b -> a,
a -> b -> c,
a -> {d,a}
};
c
In the following example, we setup the typeset key so that it shows the complete names of the nodes:
a
ab
aba
ad
aa
\tikz \graph [trie, simple, layered layout,
typeset=\tikzgraphnodefullname] {
a -> b -> a,
a -> b -> c,
a -> {d,a}
};
abc
You can also use the trie key locally and later reference nodes using their full name:
a
b
c
19.4
a
\tikz \graph {
{ [trie, simple]
a -> {
b,
c -> a
}
},
a b ->[red] a c a
};
Quick Graphs
The graph syntax is powerful, but this power comes at a price: parsing the graph syntax, which is done by
TEX, can take some time. Normally, the parsing is fast enough that you will not notice it, but it can be
bothersome when you have graphs with hundreds of nodes as happens frequently when nodes are generated
algorithmically by some other program. Fortunately, when another program generated a graph specification,
we typically do not need the full power of the graph syntax. Rather, a small subset of the graph syntax
273
would suffice that allows to specify nodes and edges. For these reasons, the is a special “quick” version of
the graph syntax.
Note, however, that using this syntax will usually at most halve the time needed to parse a graph. Thus,
it really mostly makes sense in conjunction with large, algorithmically generated graphs.
(no value)
/tikz/graphs/quick
When you provide this key with a graph, the syntax of graph specifications gets restricted. You are
no longer allowed to use certain features of the graph syntax; but all features that are still allowed are
also allowed in the same way when you do not provide the quick option. Thus, leaving out the quick
option will never hurt.
Since the syntax is so severely restricted, it is easier to explain which aspects of the graph syntax will
still work:
1. A quick graph consists of a sequence of either nodes, edges sequences, or groups. These are
separated by commas or semicolons.
2. Every node is of the form
"hnode namei"/"hnode texti"[hoptionsi]
The quotation marks are mandatory. The part /"hnode texti" may be missing, in which case the
node name is used as the node text. The hoptionsi may also be missing. The hnode namei may
not contain any “funny” characters (unlike in the normal graph command).
3. Every chain is of the form
hnode speci hconnector i hnode speci hconnector i . . . hconnector i hnode speci;
Here, the hnode speci are node specifications as described above, the hconnector i is one of the four
connectors ->, <-, --, and <-> (the connector -!- is not allowed since the simple option is also
not allowed). Each connector may be followed by options in square brackets. The semicolon may
be replaced by a comma.
4. Every group is of the form
{ [hoptionsi] hchains and groupsi };
The hoptionsi are compulsory. The semicolon can, again, be replaced by a comma.
5. The number nodes option will work as expected.
Here is a typical way this syntax might be used:
a
foo
\tikz \graph [quick] { "a" --["foo"] "b"[x=1] };
b
d
a
b
c
\tikz \graph [quick] {
"a"/"$a$" -- "b"[x=1] --[red] "c"[x=2];
{ [nodes=blue] "a" -- "d"[y=1]; };
};
Let us now have a look at the most important things that will not work when the quick option is used:
• Connecting a node and a group as in a->{b,c}.
• Node names without quotation marks as in a--b.
• Everything described in subsequent subsections, which includes subgraphs (graph macros), graph
sets, graph color classes, anonymous nodes, the fresh nodes option, sublayouts, simple graphs,
edge annotations.
• Placement strategies – you either have to define all node positions explicitly using at= or x= and
y= or you must use a graph drawing algorithm like layered layout.
274
19.5
Simple Versus Multi-Graphs
The graph library allows you to construct both simple graphs and multi-graphs. In a simple graph there can
be at most one edge between any two vertices, while in a multi-graph there can be multiple edges (hence the
name). The two keys multi and simple allow you to switch (even locally inside on of the graph’s scopes)
between which kind of graph is being constructed. By default, the graph command produces a multi-graph
since these are faster to construct.
(no value)
/tikz/graphs/multi
When this edge is set for a whole graph (which is the default) or just for a group (which is useful if the
whole graph is simple in general, but a part is a multi-graph), then when you specify an edge between
two nodes several times, several such edges get created:
a
b
\tikz \graph [multi] { % "multi" is not really necessary here
a ->[bend left, red] b;
a ->[bend right, blue] b;
};
In case multi is used for a scope inside a larger scope where the simple option is specified, then inside
the local multi scope edges are immediately created and they are completely ignored when it comes to
deciding which kind of edges should be present in the surrounding simple graph. From the surrounding
scope’s point of view it is as if the local multi graph contained no edges at all.
This means, in particular, that you can use the multi option with a single edge to “enforce” this edge
to be present in a simple graph.
(no value)
/tikz/graphs/simple
In contrast a multi-graph, in a simple graph, at most one edge gets created for every pair of vertices:
a
b
\tikz \graph [simple]{
a ->[bend left, red] b;
a ->[bend right, blue] b;
};
As can be seen, the second edge “wins” over the first edge. The general rule is as follows: In a simple
graph, whenever an edge between two vertices is specified multiple times, only the very last specification
and its options will actually be executed.
The real power of the simple option lies in the fact that you can first create a complicated graph and
then later redirect and otherwise modify edges easily:
a
e
b
f
c
g
d
h
\tikz \graph [simple, grow right=2cm] {
{a,b,c,d} ->[complete bipartite] {e,f,g,h};
{ [edges={red,thick}] a -> e -> d -> g -> a };
};
One particularly interesting kind of edge specification for a simple graph is -!-. Recall that this is used
to indicate that “no edge” should be added between certain nodes. In a multi-graph, this key usually
has no effect (unless the key new -!- has been redefined) and is pretty superfluous. In a simple graph,
however, it counts as an edge kind and you can thus use it to remove an edge that been added previously:
8
1
2
7
3
6
5
4
\tikz \graph [simple] {
subgraph K_n [n=8, clockwise];
% Get rid of the following edges:
1 -!- 2;
3 -!- 4;
6 -!- 8;
% And make one edge red:
1 --[red] 3;
};
275
Creating a graph such as the above in other fashions is pretty awkward.
For every unordered pair {u, v} of vertices at most one edge will be created in a simple graph. In
particular, when you say a -> b and later also a <- b, then only the edge a <- b will be created.
Similarly, when you say a -> b and later b -> a, then only the edge b -> a will be created.
The power of the simple command comes at a certain cost: As the graph is being constructed, a
(sparse) array is created that keeps track for each edge of the last edge being specified. Then, at the
end of the scope containing the simple command, for every pair of vertices the edge is created. This is
implemented by two nested loops iterating over all possible pairs of vertices – which may take quite a
while in a graph of, say, 1000 vertices. Internally, the simple command is implemented as an operator
that adds the edges when it is called, but this should be unimportant in normal situations.
19.6
Graph Edges: Labeling and Styling
When the graph library creates an edge between two nodes in a graph, the appearance (called “styling” in
Tik Z) can be specified in different ways. Sometimes you will simply wish to say “the edges between these
two groups of node should be red,” but sometimes you may wish to say “this particular edge going into this
node should be red.” In the following, different ways of specifying such styling requirements are discussed.
Note that adding labels to edges is, from Tik Z’s point of view, almost the same as styling edges, since they
are also specified using options.
19.6.1
Options For All Edges Between Two Groups
When you write ... ->[options] ... somewhere inside your graph specification, this typically cause one
or more edges to be created between the nodes in the chain group before the -> and the nodes in the chain
group following it. The options are applied to all of them. In particular, if you use the quotes library and
you write some text in quotes inside the options, this text will be added as a label to each edge:
a x
x
x
b x
c
d
\tikz
\graph [edge quotes=near start] {
{ a, b } -> [red, "x", complete bipartite] { c, d };
};
As documented in the quotes library in more detail, you can easily modify the appearance of edge labels
created using the quotes syntax by adding options after the closing quotes:
a
x
b y c
z
d
\tikz \graph {
a ->["x"] b ->["y"’] c ->["z" red] d;
};
The following options make it easy to setup the styling of nodes created in this way:
/tikz/graphs/edge quotes=hoptionsi
A shorthand for setting the style every edge quotes to hoptionsi.
a
x
b y c
b
(no default)
\tikz \graph [edge quotes={blue,auto}] {
a ->["x"] b ->["y"’] c ->["b" red] d;
d
};
(no value)
/tikz/graphs/edge quotes center
A shorthand for edge quotes to anchor=center.
a x b y c z d
\tikz \graph [edge quotes center] {
a ->["x"] b ->["y"] c ->["z" red] d;
};
(no value)
/tikz/graphs/edge quotes mid
A shorthand for edge quotes to anchor=mid.
a x b y c z d
\tikz \graph [edge quotes mid] {
a ->["x"] b ->["y"] c ->["z" red] d;
};
276
19.6.2
Changing Options For Certain Edges
Consider the following tree-like graph:
a
b
\tikz \graph { a -> {b,c} };
c
Suppose we wish to specify that the edge from a to b should be red, while the edge from a to c should
be blue. The difficulty lies in the fact that both edges are created by the single -> operator and we can only
add one of these option red or blue to the operator.
There are several ways to solve this problem. First, we can simply split up the specification and specify
the two edges separately:
a
b
c
\tikz \graph {
a -> [red] b;
a -> [blue] c;
};
While this works quite well, we can no longer use the nice chain group syntax of the graphs library. For
the rather simple graph a->{b,c} this is not a big problem, but if you specify a tree with, say, 30 nodes it
is really worthwhile being able to specify the tree “in its natural form in the TEX code” rather than having
to list all of the edges explicitly. Also, as can be seen in the above example, the node placement is changed,
which is not always desirable.
One can sidestep this problem using the simple option: This option allows you to first specify a graph
and then, later on, replace edges by other edges and, thereby, provide new options:
a
b
c
\tikz \graph [simple] {
a -> {b,c};
a -> [red] b;
a -> [blue] c;
};
The first line is the original specification of the tree, while the following two lines replace some edges of
the tree (in this case, all of them) by edges with special options. While this method is slower and in the
above example creates even longer code, it is very useful if you wish to, say, highlight a path in a larger
tree: First specify the tree normally and, then, “respecify” the path or paths with some other edge options
in force. In the following example, we use this to highlight a whole subtree of a larger tree:
a
b
c
d
e
f
g
\tikz \graph [simple] {
% The larger tree, no special options in force
a -> {
b -> {c,d},
e -> {f,g},
h
},
{ [edges=red] % Now highlight a part of the tree
a -> e -> {f,g}
}
};
h
19.6.3
Options For Incoming and Outgoing Edges
When you use the syntax ... ->[options] ... to specify options, you specify options for the “connections
between two sets of nodes”. In many cases, however, it will be more natural to specify options “for the edges
lead to or coming from a certain node” and you will want to specify these options “at the node”. Returning
to the example of the graph a->{b,c} where we want a red edge between a and b and a blue edge between
a and c, this could also be phrased as follows: “Make the edge leading to b red and make the edge leading
to c blue.”
For this situation, the graph library offers a number of special keys, which are documented in the
following. However, most of the time you will not use these keys directly, but, rather, use a special syntax
explained in Section 19.6.4.
277
(no default)
/tikz/graphs/target edge style=hoptionsi
This key can (only) be used with a node inside a graph specification. When used, the hoptionsi will be
added to every edge that is created by a connector like -> in which the node is a target. Consider the
following example:
a
c
e
b
d
f
\tikz \graph {
{ a, b } ->
{ c [target edge style=red], d } ->
{ e, f }
};
In the example, only when the edge from a to c is created, c is the “target” of the edge. Thus, only this
edge becomes red.
When an edge already has options set directly, the hoptionsi are executed after these direct options,
thus, they “overrule” them:
a
c
e
b
d
f
\tikz \graph {
{ a, b } -> [blue, thick]
{ c [target edge style=red], d } ->
{ e, f }
};
The hoptionsi set in this way will stay attached to the node, so also for edges created later on that lead
to the node will have these options set:
a
c
e
b
d
f
\tikz \graph {
{ a, b } ->
{ c [target edge style=red], d } ->
{ e, f },
b -> c
};
Multiple uses of this key accumulate. However, you may sometimes also wish to “clear” these options
for a key since at some later point you no longer wish the hoptionsi to be added when some further
edges are added. This can be achieved using the following key:
(no value)
/tikz/graphs/target edge clear
Clears all hoptionsi for edges with the node as a target and also edge labels (see below) for this
node.
a
c
b
d
\tikz \graph {
{ a, b } ->
{ c [target edge style=red], d },
b -> c[target edge clear]
};
/tikz/graphs/target edge node=hnode specificationi
(no default)
This key works like target edge style, only the hnode specificationi will not be added as options to
any newly created edges with the current node as their target, but rather it will be added as a node
specification.
a X c
e
b
f
d
\tikz \graph {
{ a, b } ->
{ c [target edge node=node{X}], d } ->
{ e, f }
};
As for target edge style multiple uses of this key accumulate and the key target edge clear will
(also) clear all target edge nodes that have been set for a node earlier on.
(no default)
/tikz/graphs/source edge style=hoptionsi
Works exactly like target edge style, only now the hoptionsi are only added when the node is a
source of a newly created edge:
278
a
c
e
b
d
f
\tikz \graph {
{ a, b } ->
{ c [source edge style=red], d } ->
{ e, f }
};
If both for the source and also for the target of an edge hoptionsi have been specified, the options are
applied in the following order:
1. First come the options from the edge itself.
2. Then come the options contributed by the source node using this key.
3. Then come the options contributed by the target node using target node style.
a
b
\tikz \graph {
a [source edge style=red] ->[green]
b [target edge style=blue] % blue wins
};
/tikz/graphs/source edge node=hnode specificationi
(no default)
Works like source edge style and target edge node.
/tikz/graphs/source edge clear=hnode specificationi
(no default)
Works like target edge clear.
19.6.4
Special Syntax for Options For Incoming and Outgoing Edges
The keys target node style and its friends are powerful, but a bit cumbersome to write down. For this
reason, the graphs library introduces a special syntax that is based on what I call the “first-char syntax” of
keys. Inside the options of a node inside a graph, the following special rules apply:
1. Whenever an option starts with >, the rest of the options are passed to target edge style. For
instance, when you write a[>red], then this has the same effect as if you had written
a[target edge style={red}]
2. Whenever an options starts with <, the rest of the options are passed to source edge style.
3. In both of the above case, in case the options following the > or < sign start with a quote, the created
edge label is passed to source edge node or target edge node, respectively.
This is exactly what you want to happen.
Additionally, the following styles provide shorthands for “clearing” the target and source options:
(no value)
/tikz/graphs/clear >
A more easy-to-remember shorthand for target edge clear.
(no value)
/tikz/graphs/clear <
A more easy-to-remember shorthand for source edge clear.
These mechanisms make it especially easy to create trees in which the edges are labeled in some special
way:
9
h
4
c
7
2 0
a
e
j
\tikz
\graph [edge quotes={fill=white,inner sep=1pt},
grow down, branch right] {
/ -> h [>"9"] -> {
c [>"4" text=red] -> {
a [>"2", >thick],
e [>"0"]
},
j [>"7"]
}
};
279
19.6.5
Placing Node Texts on Incoming Edges
Normally, the text of a node is shown (only) inside the node. In some case, for instance when drawing certain
kind of trees, the nodes themselves should not get any text, but rather the edge leading to the node should
be labeled as in the following example:
a
b
c
d
\tikz \graph [empty nodes]
{
root -> {
a [>"a"],
b [>"b"] -> {
c [>"c"],
d [>"d"]
}
}
};
As the example shows, it is a bit cumbersome that we have to label the nodes and then specify the same
text once more using the incoming edge syntax.
For these cases, it would be better if the text of the node where not used with the node but, rather, be
passed directly to the incoming or the outgoing edge. The following styles do exactly this:
/tikz/graphs/put node text on incoming edges=hoptionsi
(no default)
When this key is used with a node or a group, the following happens:
1. The command target edge node={node[]hoptionsi]{\tikzgraphnodetext}} is executed. This
means that all incoming edges of the node get a label with the text that would usually be displayed
in the node. You can use keys like math nodes normally.
2. The command as={} is executed. This means that the node itself will display nothing.
Here is an example that show how this command is used.
b
c
d
\tikz \graph [put node text on incoming edges,
math nodes, nodes={circle,draw}]
{ a -> b -> {c, d} };
/tikz/graphs/put node text on outgoing edges=hoptionsi
(no default)
Works like the previous key, only with target replaced by source.
19.7
Graph Operators, Color Classes, and Graph Expressions
Tik Z’s graph command employs a powerful mechanism for adding edges between nodes and sets of nodes.
To a graph theorist, this mechanism may be known as a graph expression: A graph is specified by starting
with small graphs and then applying operators to them that form larger graphs and that connect and recolor
colored subsets of the graph’s node in different ways.
19.7.1
Color Classes
Tik Z keeps track of a (multi)coloring of the graph as it is being constructed. This does not mean that the
actual color of the nodes on the page will be different, rather, in the following we refer to “logical” colors in the
way graph theoreticians do. These “logical” colors are only important while the graph is being constructed
and they are “thrown away” at the end of the construction. The actual (“physical”) colors of the nodes are
set independently of these logical colors.
As a graph is being constructed, each node can be part of one or more overlapping color classes. So,
unlike what is sometimes called a legal coloring, the logical colorings that Tik Z keeps track of may assign
multiple colors to the same node and two nodes connected by an edge may well have the same color.
Color classes must be declared prior to use. This is done using the following key:
/tikz/graphs/color class=hcolor class namei
(no default)
This sets up a new color class called hcolor class namei. Nodes and whole groups of nodes can now be
colored with hcolor class namei. This is done using the following keys, which become available inside
the current scope:
280
/tikz/graphs/hcolor class name i
(no value)
This key internally uses the operator command to setup an operator that will cause all nodes
of the current group to get the “logical color” hcolor class namei. Nodes retain this color in all
encompassing scopes, unless it is explicitly changed (see below) or unset (again, see below).
a
b
c
d
\tikz \graph [color class=red] {
[cycle=red] % causes all "logically" red nodes to be connected in
% a cycle
a,
b [red],
{ [red] c ->[bend right] d },
e
};
e
r1
g3
r2
g2
g1
\tikz \graph [color class=red, color class=green,
math nodes, clockwise, n=5] {
[complete bipartite={red}{green}]
{ [red]
r_1, r_2 },
{ [green] g_1, g_2, g_3 }
};
/tikz/graphs/not hcolor class name i
(no value)
Sets up an operator for the current scope so that all nodes in it loose the color hcolor class namei.
You can also use !hcolor class namei as an alias for this key.
r1
g3
r2
g2
g1
\tikz \graph [color class=red, color class=green,
math nodes, clockwise, n=5] {
[complete bipartite={red}{green}]
{ [red]
r_1, r_2 },
{ [green] g_1, g_2, g_3 },
g_2 [recolor green by=red]
};
/tikz/graphs/recolor hcolor class name i by=hnew color i
(no default)
Causes all keys having color hcolor class namei to get hnew color i instead. They loose having color
hcolor class namei, but other colors are not affected.
r1
g3
r2
g2
g1
\tikz \graph [color class=red, color class=green,
math nodes, clockwise, n=5] {
[complete bipartite={red}{green}]
{ [red]
r_1, r_2 },
{ [green] g_1, g_2, g_3 },
g_2 [not green]
};
The following color classes are available by default:
• Color class all. Every node is part of this class by default. This is useful to access all nodes of a
(sub)graph, since you can simply access all nodes of this color class.
• Color classes source and target. These classes are used to identify nodes that lead “into” a group of
nodes and nodes from which paths should “leave” the group. Details on how these colors are assigned
are explained in Section 19.7.3. By saying not source or not target with a node, you can influence
how it is connected:
a
b
e
\tikz \graph { a -> { b, c, d } -> e };
c
d
281
a
e
b
\tikz \graph { a -> { b[not source], c, d[not target] } -> e };
c
d
• Color classes source’ and target’. These are temporary colors that are also explained in Section 19.7.3.
19.7.2
Graph Operators on Groups of Nodes
Recall that the graph command constructs graphs recursively from nested hgroup specificationsi. Each such
hgroup specificationi describes a subset of the nodes of the final graph. A graph operator is an algorithm
that gets the nodes of a group as input and (typically) adds edges between these nodes in some sensible way.
For instance, the clique operator will simply add edges between all nodes of the group.
(no default)
/tikz/graphs/operator=hcodei
This key has an effect in three places:
1. It can be used in the hoptionsi of a hdirect node specificationi.
2. It can be used in the hoptionsi of a hgroup specificationi.
3. It can be used in the hoptionsi of an hedge specificationi.
The first case is a special case of the second, since it is treated like a group specification containing a
single node. The last case is more complicated and discussed in the next section. So, let us focus on
the second case.
Even though the hoptionsi of a group are given at the beginning of the hgroup specificationi, the hcodei
is only executed when the group has been parsed completely and all its nodes have been identified. If
you use the operator multiple times in the hoptionsi, the effect accumulates, that is, all code passed to
the different calls of operator gets executed in the order it is encountered.
The hcodei can do “whatever it wants,” but it will typically add edges between certain nodes. You can
configure what kind of edges (directed, undirected, etc.) are created by using the following keys:
(no default, initially –)
/tikz/graphs/default edge kind=hvaluei
This key stores one of the five edge kinds --, <-, ->, <->, and -!-. When an operator wishes to
create a new edge, it should typically set
\tikzgraphsset{new \pfkeysvalueof{/tikz/graphs/default edge kind}=...}
While this key can be set explicitly, it may be more convenient to use the abbreviating keys listed
below. Also, this key is automatically set to the current value of hedge specificationi when a joining
operator is called, see the discussion of joining operators in Section 19.7.3.
(no value)
/tikz/graphs/–
Sets the default edge kind to --.
\tikz \graph { subgraph K_n [--, n=5, clockwise, radius=6mm] };
1
5
2
4
3
(no value)
/tikz/graphs/->
Sets the default edge kind to ->.
\tikz \graph { subgraph K_n [->, n=5, clockwise, radius=6mm] };
1
5
2
4
3
282
(no value)
/tikz/graphs/
Sets the default edge kind to <->.
\tikz \graph { subgraph K_n [<->, n=5, clockwise, radius=6mm] };
1
5
2
4
3
(no value)
/tikz/graphs/-!Sets the default edge kind to -!-.
When the hcodei of an operator is executed, the following commands can be used to find the nodes that
should be connected:
\tikzgraphforeachcolorednode{hcolor namei}{hmacroi}
When this command is called inside hcodei, the following will happen: Tik Z will iterate over all
nodes inside the just-specified group that have the color hcolor namei. The order in which they
are iterated over is the order in which they appear inside the group specification (if a node is
encountered several times inside the specification, only the first occurrence counts). Then, for each
node the hmacroi is executed with the node’s name as the only argument.
In the following example we use an operator to connect every node colored all inside the subgroup
to he node root.
root
x
\def\myconnect#1{\tikzset{graphs/new ->={root}{#1}{}{}}}
a
\begin{tikzpicture}
\node (root) at (-1,-1) {root};
b
c
\graph {
x,
{
[operator=\tikzgraphforeachcolorednode{all}{\myconnect}]
a, b, c
}
};
\end{tikzpicture}
\tikzgraphpreparecolor{hcolor namei}{hcounter i}{hprefix i}
This command is used to “prepare” the nodes of a certain color for random access. The effect is
the following: It is counted how many nodes there are having color hcolor namei in the current
group and the result is stored in hcounter i. Next, macros named hprefix i1, hprefix i2, and so on
are defined, that store the names of the first, second, third, and so on node having the color hcolor
namei.
The net effect is that after you have prepared a color, you can quickly iterate over them. This is
especially useful when you iterate over several color at the same time.
As an example, let us create an operator then adds a zig-zag path between two color classes:
283
a
d
b
e
c
f
\newcount\leftshorecount
\newcount\rightshorecount
\newcount\mycount
\newcount\myothercount
\def\zigzag{
\tikzgraphpreparecolor{left shore}\leftshorecount{left shore prefix}
\tikzgraphpreparecolor{right shore}\rightshorecount{right shore prefix}
\mycount=0\relax
\loop
\advance\mycount by 1\relax%
% Add the "forward" edge
\tikzgraphsset{new ->=
{\csname left shore prefix\the\mycount\endcsname}
{\csname right shore prefix\the\mycount\endcsname}{}{}}
\myothercount=\mycount\relax%
\advance\myothercount by1\relax%
\tikzgraphsset{new <-=
{\csname left shore prefix\the\myothercount\endcsname}
{\csname right shore prefix\the\mycount\endcsname}{}{}}
\ifnum\myothercount<\leftshorecount\relax
\repeat
}
\begin{tikzpicture}
\graph [color class=left shore, color class=right shore]
{ [operator=\zigzag]
{ [left shore, Cartesian placement]
a, b, c },
{ [right shore, Cartesian placement, nodes={xshift=1cm}] d, e, f }
};
\end{tikzpicture}
Naturally, in order to turn the above code into a usable operator, some more code would be needed
(like default values and taking care of shores of different sizes).
There are a number of predefined operators, like clique or cycle, see the reference Section 19.10 for a
complete list.
19.7.3
Graph Operators for Joining Groups
When you join two nodes foo and bar by the edge specification ->, it is fairly obvious, what should happen:
An edge from (foo) to (bar) should be created. However, suppose we use an edge specification between
two node sets like {a,b,c} and {d,e,f}. In this case, it is not so clear which edges should be created. One
might argue that all possible edges from any node in the first set to any node in the second set should be
added. On the other hand, one might also argue that only a matching between these two sets should be
created. Things get even more muddy when a longer chain of node sets are joined.
Instead of fixing how edges are created between two node sets, Tik Z takes a somewhat more general,
but also more complicated approach, which can be broken into two parts. In the following, assume that the
following chain specification is given:
hspec1 i hedge specificationi hspec2 i
An example might be {a,b,c} -> {d, e->f}.
The source and target vertices. Let us start with the question of which vertices of the first node set
should be connected to vertices in the second node set.
There are two predefined special color classes that are used for this: source and target. For every group
specification, some vertices are colored as source vertices and some vertices are target vertices (a node can
both be a target and a source). Initially, every vertex is both a source and a target, but that can change as
we will see in a moment.
The intuition behind source and target vertices is that, in some sense, edges “from the outside” lead into
the group via the source vertices and lead out of the group via the target vertices. To be more precise, the
following happens:
1. The target vertices of the first group are connected to the source vertices of the second group.
2. In the group resulting from the union of the nodes from hspec1 i and hspec2 i, the source vertices are
only those from the first group, and the target vertices are only those from the second group.
Let us go over the effect of these rules for the example {a,b,c} -> {d, e->f}. First, each individual
node is initially both a source and a target vertex. Then, in {a,b,c} all nodes are still both source and
284
target vertices since just grouping vertices does not change their colors. Now, in e->f something interesting
happens for the first time: the target vertices of the “group” e (which is just the node e) are connected to the
source vertices of the “group” f. This means, that an edge is added from e to f. Then, in the resulting group
e->f the only source vertex is e and the only target vertex is f. This implies that in the group {d,e->f}
the sources are d and e and the targets are d and f.
Now, in {a,b,c} -> {d,e->f} the targets of {a,b,c} (which are all three of them) are connected to
the sources of {d,e->f} (which are just d and e). Finally, in the whole graph only a, b, and c are sources
while only d and f are targets.
a
d
b
e
f
\def\hilightsource#1{\fill [green, opacity=.25] (#1) circle [radius=2mm]; }
\def\hilighttarget#1{\fill [red,
opacity=.25] (#1) circle [radius=2mm]; }
\tikz \graph
[operator=\tikzgraphforeachcolorednode{source}{\hilightsource},
operator=\tikzgraphforeachcolorednode{target}{\hilighttarget}]
{ {a,b,c} -> {d, e->f} };
c
The next objective is to make more precise what it means that “the targets of the first graph” and the
“sources of the second graph” should be connected. We know already of a general way of connecting nodes of
a graph: operators! Thus, we use an operator for this job. For instance, the complete bipartite operator
adds an edge from every node having a certain color to every node have a certain other color. This is exactly
what we need here: The first color is “the color target restricted to the nodes of the first graph” and the
second color is “the color source restricted to the nodes of the second graph.”
However, we cannot really specify that only nodes from a certain subgraph are meant – the operator
machinery only operates on all nodes of the current graph. For this reason, what really happens is the
following: When the graph command encounters hspec1 i hedge specificationi hspec2 i, it first computes and
colors the nodes of the first and the second specification independently. Then, the target nodes of the
first graph are recolored to target’ and the source nodes of the second graph are recolored to source’.
Then, the two graphs are united into one graph and a joining operator is executed, which should add edges
between target’ and source’. Once this is done, the colors target’ and source’ get erased. Note that in
the resulting graph only the source nodes from the first graph are still source nodes and likewise for the
target nodes of the second graph.
The joining operators. The job of a joining operator is to add edges between nodes colored target’
and source’. The following rule is used to determine which operator should be chosen for performing this
job:
1. If the hedge specificationi explicitly sets the operator key to something non-empty (and also not to
\relax), then the hcodei of this operator call is used.
2. Otherwise, the current value of the following key is used:
/tikz/graphs/default edge operator=hkeyi
(no default)
This key stores the name of a hkeyi that is executed for every hedge specificationi whose hoptionsi
do not contain the operator key.
a
c
f
i
b
d
g
j
e
h
k
\tikz
{a,
{c,
{f,
{i,
};
\graph [default edge operator=matching] {
b}
->[matching and star]
d, e} --[complete bipartite]
g, h} -j, k}
A typical joining operator is complete bipartite. It takes the names of two color classes as input and
adds edges from all vertices of the first class to all vertices of the second class. Now, the trick is that the
default value for the complete bipartite key is {target’}{source’}. Thus, if you just write ->[complete
bipartite], the same happens as if you had written
->[complete bipartite={target’}{source’}]
This is exactly what we want to happen. The same default values are also set for other joining operators
like matching or butterfly.
285
Even though an operator like complete bipartite is typically used together with an edge specification,
it can also be used as a normal operator together with a group specification. In this case, however, the color
classes must be named explicitly:
r1
g1
r2
g2
r3
g3
\begin{tikzpicture}
\graph [color class=red, color class=green, math nodes]
{ [complete bipartite={red}{green}]
{ [red,
Cartesian placement]
r_1, r_2, r_3 },
{ [green, Cartesian placement, nodes={xshift=1cm}] g_1, g_2, g_3 }
};
\end{tikzpicture}
A list of predefined joining operators can be found in the reference Section 19.10.
The fact that joining operators can also be used as normal operators leads to a subtle problem: A normal
operator will typically use the current value of default edge kind to decide which kind of edges should be
put between the identified vertices, while a joining operator should, naturally, use the kind of edge specified
by the hedge specificationi. This problem is solved as follows: Like a normal operator, a joining operator
should also use the current value of default edge kind for the edges it produces. The trick is that this
will automatically be set to the current hedge specificationi when the operator explicitly in the hoptionsi of
the edge specification or implicitly in the default edge operator.
19.8
Graph Macros
A graph macro is a small graph that is inserted at some point into the graph that is currently being
constructed. There is special support for such graph macros in Tik Z. You might wonder why this is necessary
– can’t one use TEX’s normal macro mechanism? The answer is “no”: one cannot insert new nodes into a
graph using normal macros because the chains, groups, and nodes are determined prior to macro expansion.
Thus, any macro encountered where some node text should go will only be expanded when this node is being
named and typeset.
A graph macro is declared using the following key:
/tikz/graphs/declare={hgraph namei}{hspecificationi}
(no default)
This key declares that hgraph namei can subsequently be used as a replacement for a hnode namei.
Whenever the hgraph namei is used in the following, a graph group will be inserted instead whose
content is exactly hspecificationi. In case hgraph namei is used together with some hoptionsi, they are
executed prior to inserting the hspecificationi.
a
1
2
3
4
\tikz \graph [branch down=4mm, declare={claw}{1 -- {2,3,4}}] {
a;
claw;
b;
};
b
In the next example, we use a key to configure a subgraph:
root
1
2
3
4
5
\tikz \graph [ n/.code=\def\n{#1}, branch down=4mm,
declare={star}{root -- { \foreach \i in {1,...,\n} {\i} }}]
{ star [n=5]; };
Actually, the n key is already defined internally for a similar purpose.
As a last example, let us define a somewhat more complicated graph macro.
286
\newcount\mycount
\tikzgraphsset{
levels/.store in=\tikzgraphlevel,
levels=1,
declare={bintree}{%
[/utils/exec={%
\ifnum\tikzgraphlevel=1\relax%
\def\childtrees{ / }%
\else%
\mycount=\tikzgraphlevel%
\advance\mycount by-1\relax%
\edef\childtrees{
/ -> {
bintree[levels=\the\mycount],
bintree[levels=\the\mycount]
}}
\fi%
},
parse/.expand once=\childtrees
]
% Everything is inside the \childtrees...
}
}
\tikz \graph [grow down=5mm, branch right=5mm] { bintree [levels=5] };
Note that when you use a graph macro several time inside the same graph, you will typically have to use
the name option so that different copies of the subgraph are created:
1
1
2
3
4
2
3
4
\tikz \graph [branch down=4mm, declare={claw}{1 -- {2,3,4}}] {
claw [name=left],
claw [name=right]
};
You will find a list of useful graph macros in the reference section, Section 19.10.1.
19.9
Online Placement Strategies
The main job of the graph library is to make it easy to specify which nodes are present in a graph and
how they are connected. In contrast, it is not the primary job of the library to compute good positions for
nodes in a graph – use for instance a \matrix, specify good positions “by hand” or use the graph drawing
facilities. Nevertheless, some basic support for automatic node placement is provided for simple cases. The
graph library will provide you with information about the position of nodes inside their groups and chains.
As a graph is being constructed, a placement strategy is used to determine a (reasonably good) position
for the nodes as they are created. These placement strategies get some information about what Tik Z has
already seen concerning the already constructed nodes, but it gets no information concerning the upcoming
nodes. Because of this lack of information concerning the future, the strategies need to be what is called an
online strategy in computer science. (The opposite are offline strategies, which get information about the
whole graph and all the sizes of the nodes in it. The graph drawing libraries employ such offline strategies.)
Strategies are selected using keys like no placement or Cartesian placement. It is permissible to use
different strategies inside different parts of a graph, even though the different strategies do not always work
together in perfect harmony.
19.9.1
Manual Placement
(no value)
/tikz/graphs/no placement
This strategy simply “switches off” the whole placement mechanism, causing all nodes to be placed at
the origin by default. You need to use this strategy if you position nodes “by hand”. For this, you can
use the at key, the shift keys:
c
a
b
\tikz \graph [no placement]
{
a[at={(0:0)}] -> b[at={(1,0)}] -> c[yshift=1cm];
};
287
Since the syntax and the many braces and parentheses are a bit cumbersome, the following two keys
might also be useful:
/tikz/graphs/x=hx dimensioni
(no default)
When you use this key, it will have the same effect as if you had written at={(hx dimensioni,hy
dimensioni)}, where hy dimensioni is a value set using the y key:
c
a
b
\tikz \graph [no placement]
{
a[x=0,y=0] -> b[x=1,y=0] -> c[x=0,y=1];
};
Note that you can specify an x or a y key for a whole scope and then vary only the other key:
c
a
b
\tikz \graph [no placement]
{
a ->
{ [x=1] % group option
b [y=0] -> c[y=1]
};
};
Note that these keys have the path /tikz/graphs/, so they will be available inside graphs and
will not clash with the usual x and y keys of Tik Z, which are used to specify the basic lengths of
vectors.
/tikz/graphs/y=hy dimensioni
(no default)
See above.
19.9.2
Placement on a Grid
(no value)
/tikz/graphs/Cartesian placement
This strategy is the default strategy. It works, roughly, as follows: For each new node on a chain,
advance a “logical width” counter and for each new node in a group, advance a “logical depth” counter.
When a chain contains a whole group, then the “logical width” taken up by the group is the maximum
over the logical widths taken up by the chains inside the group; and symmetrically the logical depth of
a chain is the maximum of the depths of the groups inside it.
This slightly confusing explanation is perhaps best exemplified. In the below example, the two numbers
indicate the two logical width and depth of each node as computed by the graph library. Just ignore
the arcane code that is used to print these numbers.
a
0
0
b
0
1.0
c
d
e
f
g
j
0
2.0
1.0
2.0
2.0
2.0
3.0
2.0
4.0
2.0
5.0
2.0
k
l
0
4.0
1.0
4.0
h
i
2.0
3.0
3.0
3.0
\tikz
\graph [nodes={align=center, inner sep=1pt}, grow right=7mm,
typeset={\tikzgraphnodetext\\[-4pt]
\tiny\mywidth\\[-6pt]\tiny\mydepth},
placement/compute position/.append code=
\pgfkeysgetvalue{/tikz/graphs/placement/width}{\mywidth}
\pgfkeysgetvalue{/tikz/graphs/placement/depth}{\mydepth}]
{
a,
b,
c -> d -> {
e -> f -> g,
h -> i
} -> j,
k -> l
};
You will find a detailed description of how these logical units are computed, exactly, in Section 19.9.6.
Now, even though we talk about “widths” and “depths” and even though by default a graph “grows” to
the right and down, this is by no means fixed. Instead, you can use the following keys to change how
widths and heights are interpreted:
(no default, initially (1,0))
/tikz/graphs/chain shift=hcoordinatei
288
Under the regime of the Cartesian placement strategy, each node is shifted by the current logical
width times this hcoordinatei.
c
b
a
\tikz \graph [chain shift=(45:1)] {
a -> b -> c;
d -> e;
f -> g -> h;
};
e
h
d
g
f
(no default, initially (0,-1))
/tikz/graphs/group shift=hcoordinatei
Like for chain shift, each node is shifted by the current logical depth times this hcoordinatei.
c
b
a
e
h
g
d
\tikz \graph [chain shift=(45:7mm), group shift=(-45:7mm)] {
a -> b -> c;
d -> e;
f -> g -> h;
};
f
/tikz/graphs/grow up=hdistancei
(default 1)
Sets the chain shift to (hdistancei,0), so that chains “grow upward.” The distance by which the
center of each new element is removed from the center of the previous one is hdistancei.
c
\tikz \graph [grow up=7mm] { a -> b -> c};
b
a
(default 1)
/tikz/graphs/grow down=hdistancei
Like grow up.
a
\tikz \graph [grow down=7mm] { a -> b -> c};
b
c
(default 1)
/tikz/graphs/grow left=hdistancei
Like grow up.
c
b
a
\tikz \graph [grow left=7mm] { a -> b -> c};
(default 1)
/tikz/graphs/grow right=hdistancei
Like grow up.
a
b
c
\tikz \graph [grow right=7mm] { a -> b -> c};
289
(default 1)
/tikz/graphs/branch up=hdistancei
Sets the group shift so that groups “branch upward.” The distance by which the center of each new
element is removed from the center of the previous one is hdistancei.
e
\tikz \graph [branch up=7mm] { a -> b -> {c, d, e} };
d
a
c
b
Note that when you draw a tree, the branch ... keys specify how siblings (or adjacent branches) are
arranged, while the grow ... keys specify in which direction the branches “grow”.
(default 1)
/tikz/graphs/branch down=hdistancei
a
c
b
\tikz \graph [branch down=7mm] { a -> b -> {c, d, e}};
d
e
(default 1)
/tikz/graphs/branch left=hdistancei
a
\tikz \graph [branch left=7mm, grow down=7mm] { a -> b -> {c, d, e}};
b
e
d
c
(default 1)
/tikz/graphs/branch right=hdistancei
\tikz \graph [branch right=7mm, grow down=7mm] { a -> b -> {c, d, e}};
a
b
c
d
e
The following keys place nodes in a N × M grid.
(no value)
/tikz/graphs/grid placement
This key works similar to Cartesian placement. As for that placement strategy, a node has logical
width and depth 1. However, the computed total width and depth are mapped to a N × M grid. The
values of N and M depend on the size of the graph and the value of wrap after.
The number of
√
columns M is either set to wrap after explicitly or computed automatically as |V|. N is the number
of rows needed to lay out the graph in a grid with M columns.
1
2
3
4
5
6
1
2
3
4
5
6
7
8
9
% An example with 6 nodes, 3 columns and therefor 2 rows
\tikz \graph [grid placement] { subgraph I_n[n=6, wrap after=3] };
% An example with 9 nodes with columns and rows computed automatically
\tikz \graph [grid placement] { subgraph Grid_n [n=9] };
290
9
8
7
6
5
4
3
2
1
% Directions can be changed
\tikz \graph [grid placement, branch up, grow left] { subgraph Grid_n [n=9] };
In case a user-defined graph instead of a pre-defined subgraph is to be layed out using grid placement,
n has to be specified explicitly:
19.9.3
a
b
c
d
e
f
\tikz \graph [grid placement] {
[n=6, wrap after=3]
a -- b -- c -- d -- e -- f
};
Placement Taking Node Sizes Into Account
Options like grow up or branch right do not take the sizes of the to-be-positioned nodes into account – all
nodes are placed quite “dumbly” at grid positions. It turns out that the Cartesian placement can also be
used to place notes in such a way that their height and/or width is taken into account. Note, however, that
while the following options may yield an adequate placement in many situations, when you need advanced
alignments you should use a matrix or advanced offline strategies to place the nodes.
(default 1em)
/tikz/graphs/grow right sep=hdistancei
This key has several effects, but let us start with the bottom line: Nodes along a chain are placed in
such a way that the left end of a new node is hdistancei from the right end of the previous node:
start
long text
more text
short
end
very long text
long
longer
longest
\tikz \graph [grow right sep, left anchor=east, right anchor=west] {
start -- {
long text -- {short, very long text} -- more text,
long -- longer -- longest
} -- end
};
What happens internally is the following: First, the anchor of the nodes is set to west (or north west
or south west, see below). Second, the logical width of a node is no longer 1, but set to the actual
width of the node (which we define as the horizontal difference between the west anchor and the east
anchor) in points. Third, the chain shift is set to (1pt,0pt).
(default 1em)
/tikz/graphs/grow left sep=hdistancei
longest
longer
long
\tikz \graph [grow left sep] { long -- longer -- longest };
(default 1em)
/tikz/graphs/grow up sep=hdistancei
291
\tikz \graph [grow up sep] {
a / $a=x$ -b / {$b=\displaystyle \int_0^1 x dx$} -c [draw, circle, inner sep=7mm]
};
c
1
Z
b=
xdx
0
a=x
(default 1em)
/tikz/graphs/grow down sep=hdistancei
As above.
(default 1em)
/tikz/graphs/branch right sep=hdistancei
This key works like grow right sep, only it affects groups rather than chains.
start
an even longer text
short
very long text
more text
long
some text
longer
a
longest
b
end
\tikz \graph [grow
start -- {
an even longer
long -- longer
some text -- a
} -- end
};
down, branch right sep] {
text -- {short, very long text} -- more text,
-- longest,
-- b
When both this key and, say, grow down sep are set, instead of the west anchor, the north west
anchor will be selected automatically.
(default 1em)
/tikz/graphs/branch left sep=hdistancei
start
some text
a
b
long
longer
an even longer text
very long text
short
more text
end
\tikz \graph [grow down sep, branch left sep] {
start -- {
an even longer text -- {short, very long text} -- more text,
long -- longer,
some text -- a -- b
} -- end
};
292
(default 1em)
/tikz/graphs/branch up sep=hdistancei
\tikz \graph [branch up sep] { a, b, c[draw, circle, inner sep=7mm] };
c
b
a
(default 1em)
/tikz/graphs/branch down sep=hdistancei
19.9.4
Placement On a Circle
The following keys place nodes on circles. Note that, typically, you do not use circular placement directly,
but rather use one of the two keys clockwise or counterclockwise.
(no value)
/tikz/graphs/circular placement
This key works quite similar to Cartesian placement. As for that placement strategy, a node has logical
width and depth 1. However, the computed total width and depth are mapped to polar coordinates
rather than Cartesian coordinates.
/tikz/graphs/chain polar shift=(hanglei:hradiusi)
(no default, initially (0:1))
Under the regime of the circular placement strategy, each node on a chain is shifted by (hlogical
widthihanglei:hlogical widthihanglei).
c
b
e
\tikz \graph [circular placement] {
a -> b -> c;
d -> e;
f -> g -> h;
};
a
d
f
g
h
/tikz/graphs/group polar shift=(hanglei:hradiusi)
(no default, initially (45:0))
Like for group shift, each node on a chain is shifted by (hlogical depthihanglei:hlogical
depthihanglei).
c
b
e
h
g
d
\tikz \graph [circular placement, group polar shift=(30:0)] {
a -> b -> c;
d -> e;
f -> g -> h;
};
a
f
293
f
g
d
e
h
b
a
\tikz \graph [circular placement,
chain polar shift=(30:0),
group polar shift=(0:1cm)] {
a -- b -- c;
d -- e;
f -- g -- h;
};
c
(no default, initially 1cm)
/tikz/graphs/radius=hdimensioni
This is an initial value that is added to the total computed radius when the polar shift of a node
has been calculated. Essentially, this key allows you to set the hradiusi of the innermost circle.
b
c
a
\tikz \graph [circular placement, radius=5mm] { a, b, c, d };
d
a
\tikz \graph [circular placement, radius=1cm] { a, b, c, d };
b
c
d
(no default, initially 90)
/tikz/graphs/phase=hanglei
This is an initial value that is added to the total computed angle when the polar shift of a node
has been calculated.
a
\tikz \graph [circular placement] { a, b, c, d };
b
c
d
c
\tikz \graph [circular placement, phase=0] { a, b, c, d };
b
a
d
/tikz/graphs/clockwise=hnumber i
(default \tikzgraphVnum)
This key sets the group shift so that if there are exactly hnumber i many nodes in a group, they will
form a complete circle. If you do not provide a hnumber i, the current value of \tikzgraphVnum is used,
which is exactly what you want when you use predefined graph macros like subgraph K_n.
\tikz \graph [clockwise=4] { a, b, c, d };
a
d
b
c
294
\tikz \graph [clockwise] { subgraph K_n [n=5] };
1
5
2
4
3
/tikz/graphs/counterclockwise=hnumber i
(default \tikzgraphVnum)
Works like clockwise, only the direction is inverted.
19.9.5
Levels and Level Styles
As a graph is being parsed, the graph command keeps track of a parameter called the level of a node.
Provided that the graph is actually constructed in a tree-like manner, the level is exactly equal to the level
of the node inside this tree.
(no value)
/tikz/graphs/placement/level
This key stores a number that is increased for each element on a chain, but gets reset at the end of a
group:
a:1
b:2
c:2
d:3
e:3
f:4
g:4
h:3
j:2
\tikz \graph [ branch down=5mm, typeset=
\tikzgraphnodetext:\pgfkeysvalueof{/tikz/graphs/placement/level}]
{
a -> {
b,
c -> {
d,
e -> {f,g},
h
},
j
}
};
Unlike the parameters depth and width described in the next section, the key level is always available.
In addition to keeping track of the value of the level key, the graph command also executes the following
keys whenever it creates a node:
/tikz/graph/level=hlevel i
(style, no default)
This key gets executed for each newly created node with hlevel i set to the current level of the node.
You can use this key to, say, reconfigure the node distance or the node color.
/tikz/graph/level hlevel i
(style, no value)
This key also gets executed for each newly created node with hlevel i set to the current level of the
node.
a
b
c
d
e
h
j
f
g
\tikz \graph [
branch down=5mm,
level 1/.style={nodes=red},
level 2/.style={nodes=green!50!black},
level 3/.style={nodes=blue}]
{
a -> {
b,
c -> {
d,
e -> {f,g},
h
},
j
}
};
295
a
b
c
d
e f
g
h
j
19.9.6
\tikz \graph [
branch down=5mm,
level 1/.style={grow right=2cm},
level 2/.style={grow right=1cm},
level 3/.style={grow right=5mm}]
{
a -> {
b,
c -> {
d,
e -> {f,g},
h
},
j
}
};
Defining New Online Placement Strategies
In the following the details of how to define a new placement strategy are explained. Most readers may wish
to skip this section.
As a graph specification is being parsed, the graph library will keep track of different numbers that
identify the positions of the nodes. Let us start with what happens on a chain. First, the following counter
is increased for each element of the chain:
(no value)
/tikz/graphs/placement/element count
This key stores a number that tells us the position of the node on the current chain. However, you
only have access to this value inside the code passed to the macro compute position, explained later
on.
a:0
b:1
d:0
e:0
f:0
c:2
j:2
h:1
\tikz \graph [
grow right sep, typeset=\tikzgraphnodetext:\mynum,
placement/compute position/.append code=
\pgfkeysgetvalue{/tikz/graphs/placement/element count}{\mynum}]
{
a -> b -> c,
d -> {e, f->h} -> j
};
As can be seen, each group resets the element counter.
The second value that is computed is more complicated to explain, but it also gives more interesting
information:
(no value)
/tikz/graphs/placement/width
This key stores the “logical width” of the nodes parsed up to now in the current group or chain (more
precisely, parsed since the last call of place in an enclosing group). This is not necessarily the “total
physical width” of the nodes, but rather a number representing how “big” the elements prior to the
current element were. This may be their width, but it may also be their height or even their number
(which, incidentally, is the default). You can use the width to perform shifts or rotations of to-be-created
nodes (to be explained later).
The logical width is defined recursively as follows. First, the width of a single node is computed by
calling the following key:
/tikz/graphs/placement/logical node width=hfull node namei
(no default)
This key is called to compute a physical or logical width of the node hfull node namei. You can
change the code of this key. The code should return the computed value in the macro \pgfmathresult. By default, this key returns 1.
The width of a chain is the sum of the widths of its elements. The width of a group is the maximum of
the widths of its elements.
To get a feeling what the above rules imply in practice, let us first have a look at an example where
each node has logical width and height 1 (which is the default). The arcane options at the beginning
of the code just setup things so that the computed width and depth of each node is displayed at the
bottom of each node.
296
a
0
0
b
0
1.0
c
d
e
f
g
j
0
2.0
1.0
2.0
2.0
2.0
3.0
2.0
4.0
2.0
5.0
2.0
k
l
0
4.0
1.0
4.0
h
i
2.0
3.0
3.0
3.0
\tikz
\graph [nodes={align=center, inner sep=1pt}, grow right=7mm,
typeset={\tikzgraphnodetext\\[-4pt]
\tiny\mywidth\\[-6pt]\tiny\mydepth},
placement/compute position/.append code=
\pgfkeysgetvalue{/tikz/graphs/placement/width}{\mywidth}
\pgfkeysgetvalue{/tikz/graphs/placement/depth}{\mydepth}]
{
a,
b,
c -> d -> {
e -> f -> g,
h -> i
} -> j,
k -> l
};
In the next example the “logical” width and depth actually match the “physical” width and height. This
is caused by the grow right sep option, which internally sets the logical node width key so that it
returns the width of its parameter in points.
a
Width: 0
Depth: 0
b
Width: 0
Depth: 31.67404
c
e
d
Width: 0
Depth: 65.93079
Width: 61.57303
Depth: 65.93079
k
l
Width: 0
Depth: 134.44427
Width: 64.97498
Depth: 134.44427
Width: 123.72232
Depth: 65.93079
f
Width: 189.27356
Depth: 65.93079
h
i
Width: 123.72232
Depth: 100.18753
Width: 189.27356
Depth: 100.18753
g
j
Width: 254.8248
Depth: 65.93079
Width: 316.97409
Depth: 65.93079
\tikz
\graph [grow right sep, branch down sep, nodes={align=left, inner sep=1pt},
typeset={\tikzgraphnodetext\\[-4pt] \tiny Width: \mywidth\\[-6pt] \tiny Depth: \mydepth},
placement/compute position/.append code=
\pgfkeysgetvalue{/tikz/graphs/placement/width}{\mywidth}
\pgfkeysgetvalue{/tikz/graphs/placement/depth}{\mydepth}]
{
a,
b,
c -> d -> {
e -> f -> g,
h -> i
} -> j,
k -> l
};
Symmetrically to chains, as a group is being constructed, counters are available for the number of chains
encountered so far in the current group and for the logical depth of the current group:
(no value)
/tikz/graphs/placement/element count
This key stores a number that tells us the sequence number of the chain in the current group.
a:0
b:0
f:1
g:2
h:2
c:0
d:1
e:2
\tikz \graph [
grow right sep, branch down=5mm, typeset=\tikzgraphnodetext:\mynum,
placement/compute position/.append code=
\pgfkeysgetvalue{/tikz/graphs/placement/chain count}{\mynum}]
{
a -> b -> {c,d,e},
f,
g -> h
};
297
(no value)
/tikz/graphs/placement/depth
Similarly to the width key, this key stores the “logical depth” of the nodes parsed up to now in the current
group or chain and, also similarly, this key may or may not be related to the actual depth/height of
the current node. As for the width, the exact definition is as follows: For a single node, the depth is
computed by the following key:
/tikz/graphs/placement/logical node depth=hfull node namei
(no default)
The code behind this key should return the “logical height” of the node hfull node namei in the
macro \pgfmathresult.
Second, the depth of a group is the sum of the depths of its elements. Third, the depth of a chain is
the maximum of the depth of its elements.
The width, depth, element count, and chain count keys get updated automatically, but do not have
an effect by themselves. This is to the following two keys:
/tikz/graphs/placement/compute position=hcodei
(no default)
The hcodei is called by the graph command just prior to creating a new node (the exact moment when
this key is called is detailed in the description of the place key). When the hcodei is called, all of the
keys described above will hold numbers computed in the way described above.
The job of the hcodei is to setup node options appropriately so that the to-be-created node will be placed
correctly. Thus, the hcodei should typically set the key nodes={shift=hcoordinatei} where hcoordinatei
is the computed position for the node. The hcodei could also set other options like, say, the color of a
node depending on its depth.
The following example appends some code to the standard code of compute position so that “deeper”
nodes of a tree are lighter. (Naturally, the same effect could be achieved much more easily using the
level key.)
a
b
c
e
f
g
h
d
\newcount\mycount
\def\lightendeepernodes{
\pgfmathsetcount{\mycount}{
100-20*\pgfkeysvalueof{/tikz/graphs/placement/width}
}
\edef\mydepth{\the\mycount}
\tikzset{nodes={fill=red!\mydepth,circle,text=white}}
}
\tikz
\graph [placement/compute position/.append code=\lightendeepernodes]
{
a -> {
b -> c -> d,
e -> {
f,
g
},
h
}
};
(no value)
/tikz/graphs/placement/place
Executing this key has two effects: First, the key compute position is called to compute a good position
for future nodes (usually, these “future nodes” are just a single node that is created immediately). Second,
all of the above counters like depth or width are reset (but not level).
There are two places where this key is sensibly called: First, just prior to creating a node, which happens
automatically. Second, when you change the online strategy. In this case, the computed width and depth
values from one strategy typically make no sense in the other strategy, which is why the new strategy
should proceed “from a fresh start.” In this case, the implicit call of compute position ensures that
the new strategy gets the last place the old strategy would have used as its starting point, while the
computation of its positions is now relative to this new starting point.
For these reasons, when an online strategy like Cartesian placement is called, this key gets called
implicitly. You will rarely need to call this key directly, except when you define a new online strategy.
298
19.10
Reference: Predefined Elements
19.10.1
Graph Macros
Tik Z Library graph.standard
\usetikzlibrary{graph.standard} % LATEX and plain TEX
\usetikzlibrary[graph.standard] % ConTEXt
This library defines a number of graph macros that are often used in the literature. When new graphs
are added to this collection, they will follow the definitions in the Mathematica program, see mathworld.wolfram.com/topics/SimpleGraphs.html.
Graph subgraph I_n
This graph consists just of n unconnected vertices. The following key is used to specify the set of these
vertices:
/tikz/graphs/V={hlist of verticesi}
(no default)
Sets a list of vertex names for use with graphs like subgraph I_n and also other graphs. This
list is available in the macro \tikzgraphV. The number of elements of this list is available in
\tikzgraphVnum.
/tikz/graphs/n=hnumber i
(no default)
This is an abbreviation for V={1,...,hnumber i}, name shore V={name=V}.
a
b
c
\tikz \graph [branch right, nodes={draw, circle}]
{ subgraph I_n [V={a,b,c}] };
This graph is not particularly exciting by itself. However, it is often used to introduce nodes into a
graph that are then connected as in the following example:
\tikz \graph [clockwise, clique] { subgraph I_n [n=4] };
1
4
2
3
Graph subgraph I_nm
This graph consists of two sets of once n unconnected vertices and then m unconnected vertices. The
first set consists of the vertices set by the key V, the other set consists of the vertices set by the key
W.
1
a
2
b
3
c
\tikz \graph { subgraph I_nm [V={1,2,3}, W={a,b,c}] };
In order to set the graph path name of the two sets, the following keys get executed:
/tikz/graphs/name shore V
(style, initially empty)
Set this style to, say, name=my V set in order to set a name for the V set.
(style, initially empty)
/tikz/graphs/name shore W
Same as for name shore V.
/tikz/graphs/W={hlist of verticesi}
(no default)
Sets the list of vertices for the W set. The elements and their number are available in the macros
\tikzgraphW and \tikzgraphWnum, respectively.
299
/tikz/graphs/m=hnumber i
(no default)
This is an abbreviation for W={1,...,hnumber i}, name shore W={name=W}.
The main purpose of this subgraph is to setup the nodes in a bipartite graph:
1
1
2
2
3
3
\tikz \graph {
subgraph I_nm [n=3, m=4];
V 1 -- { W 2, W 3 };
V 2 -- { W 1, W 3 };
V 3 -- { W 1, W 4 };
};
4
Graph subgraph K_n
This graph is the complete clique on the vertices from the V key.
\tikz \graph [clockwise] { subgraph K_n [n=7] };
1
7
2
6
3
5
4
Graph subgraph K_nm
This graph is the complete bipartite graph with the two shores V and W as in subgraph I_nm.
6
7
8
9
b
c
d
e
1
2
3
a
b
c
d
\tikz \graph [branch right, grow down]
{ subgraph K_nm [V={6,...,9}, W={b,...,e}] };
\tikz \graph [simple, branch right, grow down]
{
subgraph K_nm [V={1,2,3}, W={a,b,c,d}, ->];
subgraph K_nm [V={2,3},
W={b,c},
<-];
};
Graph subgraph P_n
This graph is the path on the vertices in V.
1
2
3
\tikz \graph [branch right] { subgraph P_n [n=3] };
Graph subgraph C_n
This graph is the cycle on the vertices in V.
\tikz \graph [clockwise] { subgraph C_n [n=7, ->] };
1
7
2
6
3
5
4
Graph subgraph Grid_n
This graph is a grid of the vertices in V.
300
/tikz/graphs/wrap after=hnumber i
(no default)
Defines the number of nodes placed in a single row of the grid. This value implicitly defines the
number of grid columns as well. In the following example a grid placement is used to visualize the
edges created between the nodes of a Grid_n subgraph using different values for wrap after.
\tikz \graph [grid placement] { subgraph Grid_n [n=3,wrap after=1] };
\tikz \graph [grid placement] { subgraph Grid_n [n=3,wrap after=3] };
1
2
3 1
19.10.2
2
3
1
2 1
2
3
4 3
4
\tikz \graph [grid placement] { subgraph Grid_n [n=4,wrap after=2] };
\tikz \graph [grid placement] { subgraph Grid_n [n=4] };
Group Operators
The following keys use the operator key to setup operators that connect the vertices of the current group
having a certain color in a specific way.
/tikz/graphs/clique=hcolor i
(default all)
Adds an edge between all vertices of the current group having the (logical) color hcolor i. Since, by
default, this color is set to all, which is a color that all nodes get by default, when you do not specify
anything, all nodes will be connected.
a
e
b
c
d
a
e
b
\tikz \graph [clockwise, n=5] {
a,
b,
{
[clique]
c, d, e
}
};
\tikz \graph [color class=red, clockwise, n=5] {
[clique=red, ->]
a, b[red], c[red], d, e[red]
};
c
d
/tikz/graphs/induced independent set=hcolor i
(default all)
This key is the “opposite” of a clique: It removes all edges in the current group having belonging to
color class hcolor i. More precisely, an edge of kind -!- is added for each pair of vertices. This means
that edge only get removed if you specify the simple option.
\tikz \graph [simple] {
subgraph K_n [<->, n=7, clockwise]; % create lots of edges
1
7
2
{ [induced independent set] 1, 3, 4, 5, 6 }
6
3
5
};
4
/tikz/graphs/cycle=hcolor i
(default all)
Connects the nodes colored hcolor i is a cyclic fashion. The ordering is the ordering in which they appear
in the whole graph specification.
301
a
f
e
b
\tikz \graph [clockwise, n=6, phase=60] {
{ [cycle, ->] a, b, c },
{ [cycle, <-] d, e, f }
};
c
d
/tikz/graphs/induced cycle=hcolor i
(default all)
While the cycle command will only add edges, this key will also remove all other edges between the
nodes of the cycle, provided we are constructing a simple graph.
\tikz \graph [simple] {
subgraph K_n [n=7, clockwise]; % create lots of edges
1
7
2
{ [induced cycle, ->, edge=red] 2, 3, 4, 6, 7 },
6
3
};
4
5
/tikz/graphs/path=hcolor i
(default all)
Works like cycle, only there is no edge from the last to the first vertex.
a
f
b
e
c
\tikz \graph [clockwise, n=6] {
{ [path, ->] a, b, c },
{ [path, <-] d, e, f }
};
d
/tikz/graphs/induced path=hcolor i
(default all)
Works like induced cycle, only there is no edge from the last to the first vertex.
\tikz \graph [simple] {
subgraph K_n [n=7, clockwise]; % create lots of edges
1
7
2
{ [induced path, ->, edges=red] 2, 3, 4, 6, 7 },
6
3
4
5
19.10.3
};
Joining Operators
The following keys are typically used as options of an hedge specificationi, but can also be called in a group
specification (however, then, the colors need to be set explicitly).
/tikz/graphs/complete bipartite=hfrom color ihto color i
(default {source’}{target’})
Adds all possible edges from every node having color hfrom color i to every node having color hto
color i:
a
c
g
b
d
h
e
i
k
\tikz \graph { {a, b}
->[complete bipartite]
{c, d, e}
--[complete bipartite]
{g, h, i, j} --[complete bipartite]
k };
j
302
a
f
b
e
c
\tikz \graph [color class=red, color class=green, clockwise, n=6] {
[complete bipartite={red}{green}, ->]
a [red], b[red], c[red], d[green], e[green], f[green]
};
d
(no value)
/tikz/graphs/induced complete bipartite
Works like the complete bipartite operator, but in a simple graph any edges between the vertices
in either shore are removed (more precisely, they get replaced by -!- edges).
\tikz \graph [simple] {
subgraph K_n [n=5, clockwise];
1
5
2
% Lots of edges
{2, 3} ->[induced complete bipartite] {4, 5}
};
4
3
/tikz/graphs/matching=hfrom color ihto color i
(default {source’}{target’})
This joining operator forms a maximum matching between the nodes of the two sets of nodes having
colors hfrom color i and hto color i, respectively. The first node of the from set is connected to the first
node of to set, the second node of the from set is connected to the second node of the to set, and so on.
If the sets have the same size, what results is what graph theoreticians call a perfect matching, otherwise
only a maximum, but not perfect matching results.
a
d
g
i
b
e
h
j
c
f
\tikz
{a,
{d,
{g,
{i,
};
\graph {
b, c} ->[matching]
e, f} --[matching]
h}
--[matching]
j, k}
k
/tikz/graphs/matching and star=hfrom color ihto color i
(default {source’}{target’})
The matching and star connector works like the matching connector, only it behaves differently when
the two to-be-connected sets have different size. In this case, all the surplus nodes get connected to the
last node of the other set, resulting in what is known as a star in graph theory. This simple rule allows
for some powerful effects (since this connector is the default, there is no need to add it here):
a
b
d
c
e
f
\tikz \graph { a -> {b, c} -> {d, e} -- f};
The matching and star connector also makes it easy to create trees and series-parallel graphs.
(no default)
/tikz/graphs/butterfly=hoptionsi
The butterfly connector is used to create the kind of connections present between layers of a so-called
butterfly network. As for other connectors, two sets of nodes are connected, which are the nodes having
color target’ and source’ by default. In a level l connection, the first l nodes of the first set are
connected to the second l nodes of the second set, while the second l nodes of the first set get connected
to the first l nodes of the second set. Then, for next 2l nodes of both sets a similar kind of connection
is installed. Additionally, each node gets connected to the corresponding node in the other set with the
same index (as in a matching):
303
1
2
3
4
5
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
9
10
11
12
\tikz \graph [left anchor=east, right anchor=west,
branch down=4mm, grow right=15mm] {
subgraph I_n [n=12, name=A] --[butterfly={level=3}]
subgraph I_n [n=12, name=B] --[butterfly={level=2}]
subgraph I_n [n=12, name=C]
};
Unlike most joining operators, the colors of the nodes in the first and the second set are not passed as
parameters to the butterfly key. Rather, they can be set using the hoptionsi, which are executed with
the path prefix /tikz/graphs/butterfly.
/tikz/graphs/butterfly/level=hlevel i
(no default, initially 1)
Sets the level l for the connections.
/tikz/graphs/butterfly/from=hcolor i
(no default, initially target’)
Sets the color class of the from nodes.
/tikz/graphs/butterfly/to=hcolor i
(no default, initially source’)
Sets the color class of the to nodes.
304
20
Matrices and Alignment
20.1
Overview
When creating pictures, one often faces the problem of correctly aligning parts of the picture. For example,
you might wish that the baselines of certain nodes should be on the same line and some further nodes
should be below these nodes with, say, their centers on a vertical lines. There are different ways of solving
such problems. For example, by making clever use of anchors, nearly all such alignment problems can be
solved. However, this often leads to complicated code. An often simpler way is to use matrices, the use of
which is explained in the current section.
A Tik Z matrix is similar to LATEX’s {tabular} or {array} environment, only instead of text each cell
contains a little picture or a node. The sizes of the cells are automatically adjusted such that they are large
enough to contain all the cell contents.
Matrices are a powerful tool and they need to be handled with some care. For impatient readers who
skip the rest of this section: you must end every row with \\. In particular, the last row must be ended
with \\.
Many of the ideas implemented in Tik Z’s matrix support are due to Mark Wibrow – many thanks to
Mark at this point!
20.2
Matrices are Nodes
Matrices are special in many ways, but for most purposes matrices are treated like nodes. This means, that
you use the node path command to create a matrix and you only use a special option, namely the matrix
option, to signal that the node will contain a matrix. Instead of the usual TEX-box that makes up the text
part of the node’s shape, the matrix is used. Thus, in particular, a matrix can have a shape, this shape
can be drawn or filled, it can be used in a tree, and so on. Also, you can refer to the different anchors of a
matrix.
/tikz/matrix=htrue or falsei
(default true)
This option can be passed to a node path command. It signals that the node will contain a matrix.
Hello
\begin{tikzpicture}
\draw[help lines] (0,0) grid (4,2);
\node [matrix,fill=red!20,draw=blue,very thick] (my matrix) at (2,1)
{
\draw (0,0)
circle (4mm); & \node[rotate=10] {Hello};
\\
\draw (0.2,0) circle (2mm); & \fill[red]
(0,0) circle (3mm); \\
};
\draw [very thick,->] (0,0) |- (my matrix.west);
\end{tikzpicture}
The exact syntax of the matrix is explained in the course of this section.
(style, initially empty)
/tikz/every matrix
This style is used in every matrix.
Even more so than nodes, matrices will often be the only object on a path. Because of this, there is a
special abbreviation for creating matrices:
\matrix
Inside {tikzpicture} this is an abbreviation for \path node[matrix].
Even though matrices are nodes, some options do not have the same effect as for normal nodes:
1. Rotations and scaling have no effect on a matrix as a whole (however, you can still transform the
contents of the cells normally). Before the matrix is typeset, the rotational and scaling part of the
transformation matrix is reset.
2. For multi-part shapes you can only set the text part of the node.
3. All options starting with text such as text width have no effect.
305
20.3
Cell Pictures
A matrix consists of rows of cells. Each row (including the last one!) is ended by the command \\. The
character & is used to separate cells. Inside each cell, you must place commands for drawing a picture,
called the cell picture in the following. (However, cell pictures are not enclosed in a complete {pgfpicture}
environment, they are a bit more light-weight. The main difference is that cell pictures cannot have layers.)
It is not necessary to specify beforehand how many rows or columns there are going to be and if a row
contains less cell pictures than another line, empty cells are automatically added as needed.
20.3.1
Alignment of Cell Pictures
For each cell picture a bounding box is computed. These bounding boxes and the origins of the cell pictures
determine how the cells are aligned. Let us start with the rows: Consider the cell pictures on the first row.
Each has a bounding box and somewhere inside this bounding box the origin of the cell picture can be found
(the origin might even lie outside the bounding box, but let us ignore this problem for the moment). The
cell pictures are then shifted around such that all origins lie on the same horizontal line. This may make it
necessary to shift some cell pictures upwards and others downwards, but it can be done and this yields the
vertical alignment of the cell pictures this row. The top of the row is then given by the top of the “highest”
cell picture in the row, the bottom of the row is given by the bottom of the lowest cell picture. (To be more
precise, the height of the row is the maximum y-value of any of the bounding boxes and the depth of the
row is the negated minimum y-value of the bounding boxes).
aXg
\begin{tikzpicture}
[every node/.style={draw=black,anchor=base,font=\huge}]
\matrix [draw=red]
{
\node {a}; \fill[blue] (0,0) circle (2pt); &
\node {X}; \fill[blue] (0,0) circle (2pt); &
\node {g}; \fill[blue] (0,0) circle (2pt); \\
};
\end{tikzpicture}
Each row is aligned in this fashion: For each row the cell pictures are vertically aligned such that the
origins lie on the same line. Then the second row is placed below the first row such that the bottom of the
first row touches the top of the second row (unless a row sep is used to add a bit of space). Then the bottom
of the second row touches the top of the third row, and so on. Typically, each row will have an individual
height and depth.
a X g
a X g
a X g
a X g
\begin{tikzpicture}
[every node/.style={draw=black,anchor=base}]
\matrix [draw=red]
{
\node {a}; & \node {X}; & \node {g}; \\
\node {a}; & \node {X}; & \node {g}; \\
};
\matrix [row sep=3mm,draw=red] at (0,-2)
{
\node {a}; & \node {X}; & \node {g}; \\
\node {a}; & \node {X}; & \node {g}; \\
};
\end{tikzpicture}
Let us now have a look at the columns. The rules for how the pictures on any given column are aligned are
very similar to the row alignment: Consider all cell pictures in the first column. Each is shifted horizontally
such that the origins lie on the same vertical line. Then, the left end of the column is at the left end of the
bounding box that protrudes furthest to the left. The right end of the column is at the right end of the
bounding box that protrudes furthest to the right. This fixes the horizontal alignment of the cell pictures
in the first column and the same happens the cell pictures in the other columns. Then, the right end of the
first column touches the left end of the second column (unless column sep is used). The right end of the
second column touches the left end of the third column, and so on. (Internally, two columns are actually
used to achieve the desired horizontal alignment, but that is only an implementation detail.)
306
Hallo
X
g
8
3
4
20.3.2
1
5
9
6
7
2
\begin{tikzpicture}[every
\matrix [draw=red]
{
\node[left] {Hallo};
\node
{X};
\node[right] {g};
};
\end{tikzpicture}
node/.style={draw}]
\fill[blue] (0,0) circle (2pt); \\
\fill[blue] (0,0) circle (2pt); \\
\fill[blue] (0,0) circle (2pt); \\
\begin{tikzpicture}[every node/.style={draw}]
\matrix [draw=red,column sep=1cm]
{
\node {8}; & \node{1}; & \node {6}; \\
\node {3}; & \node{5}; & \node {7}; \\
\node {4}; & \node{9}; & \node {2}; \\
};
\end{tikzpicture}
Setting and Adjusting Column and Row Spacing
There are different ways of setting and adjusting the spacing between columns and rows. First, you can use
the options column sep and row sep to set a default spacing for all rows and all columns. Second, you can
add options to the & character and the \\ command to adjust the spacing between two specific columns or
rows. Additionally, you can specify whether the space between two columns or rows should be considered
between the origins of cells in the column or row or between their borders.
/tikz/column sep=hspacing listi
(no default)
This option sets a default space that is added between every two columns. This space can be positive
or negative and is zero by default. The hspacing listi normally contains a single dimension like 2pt.
123
12
1
1cm
1
12
123
1
1
1
\begin{tikzpicture}
\matrix [draw,column sep=1cm,nodes=draw]
{
\node(a) {123}; & \node (b) {1};
& \node {1}; \\
\node
{12}; & \node
{12}; & \node {1}; \\
\node(c) {1};
& \node (d) {123}; & \node {1}; \\
};
\draw [red,thick] (a.east) -- (a.east |- c)
(d.west) -- (d.west |- b);
\draw [<->,red,thick] (a.east) -- (d.west |- b)
node [above,midway] {1cm};
\end{tikzpicture}
More generally, the hspacing listi may contain a whole list of numbers, separated by commas, and
occurrences of the two key words between origins and between borders. The effect of specifying
such a list is the following: First, all numbers occurring in the list are simply added to compute the final
spacing. Second, concerning the two keywords, the last occurrence of one of the keywords is important.
If the last occurrence is between borders or if neither occurs, then the space is inserted between the
two columns normally. However, if the last occurs is between origins, then the following happens:
The distance between the columns is adjusted such that the difference between the origins of all the
cells in the first column (remember that they all lie on straight line) and the origins of all the cells in
the second column is exactly the given distance.
The between origins option can only be used for columns mentioned in the first row, that is, you
cannot specify this option for columns introduced only in later rows.
307
1cm
123
1
12
12
1
123
1
1
1
\begin{tikzpicture}
\matrix [draw,column sep={1cm,between origins},nodes=draw]
{
\node(a) {123}; & \node (b) {1};
& \node {1}; \\
\node
{12}; & \node
{12}; & \node {1}; \\
\node
{1};
& \node
{123}; & \node {1}; \\
};
\draw [<->,red,thick] (a.center) -- (b.center) node [above,midway] {1cm};
\end{tikzpicture}
/tikz/row sep=hspacing listi
(no default)
This option works like column sep, only for rows. Here, too, you can specify whether the space is added
between the lower end of the first row and the upper end of the second row, or whether the space is
computed between the origins of the two rows.
123
1
1
1cm
12
12 1
1
123 1
123 1 1
1cm
12 12 1
1
123 1
\begin{tikzpicture}
\matrix [draw,row sep=1cm,nodes=draw]
{
\node (a) {123}; & \node {1};
& \node {1}; \\
\node (b) {12}; & \node {12}; & \node {1}; \\
\node
{1};
& \node {123}; & \node {1}; \\
};
\draw [<->,red,thick] (a.south) -- (b.north) node [right,midway] {1cm};
\end{tikzpicture}
\begin{tikzpicture}
\matrix [draw,row sep={1cm,between origins},nodes=draw]
{
\node (a) {123}; & \node {1};
& \node {1}; \\
\node (b) {12}; & \node {12}; & \node {1}; \\
\node
{1};
& \node {123}; & \node {1}; \\
};
\draw [<->,red,thick] (a.center) -- (b.center) node [right,midway] {1cm};
\end{tikzpicture}
The row-end command \\ allows you to provide an optional argument, which must be a dimension.
This dimension will be added to the list in row sep. This means that, firstly, any numbers you list in
this argument will be added as an extra row separation between the line being ended and the next line and,
secondly, you can use the keywords between origins and between borders to locally overrule the standard
setting for this line pair.
1cm
\begin{tikzpicture}
\matrix [row sep=1mm]
{
\draw (0,0) circle (2mm); & \draw (0,0) circle (2mm); \\
\draw (0,0) circle (2mm); & \draw (0,0) circle (2mm); \\[-1mm]
\draw (0,0) coordinate (a) circle (2mm); &
\draw (0,0) circle (2mm); \\[1cm,between origins]
\draw (0,0) coordinate (b) circle (2mm); &
\draw (0,0) circle (2mm); \\
};
\draw [<->,red,thick] (a.center) -- (b.center) node [right,midway] {1cm};
\end{tikzpicture}
The cell separation character & also takes an optional argument, which must also be a spacing list. This
spacing list is added to the column sep having a similar effect as the option for the \\ command for rows.
This optional spacing list can only be given the first time a new column is started (usually in the first
row), subsequent usages of this option in later rows have no effect.
8
3
4
1 6
5 7
9 2
\begin{tikzpicture}
\matrix [draw,nodes=draw,column sep=1mm]
{
\node {8}; &[2mm] \node{1}; &[-1mm] \node {6}; \\
\node {3}; &
\node{5}; &
\node {7}; \\
\node {4}; &
\node{9}; &
\node {2}; \\
};
\end{tikzpicture}
308
11mm
1
6
5
7
9
2
\begin{tikzpicture}
\matrix [draw,nodes=draw,column sep=1mm]
{
\node {8}; &[2mm] \node(a){1}; &[1cm,between origins] \node(b){6}; \\
\node {3}; &
\node
{5}; &
\node
{7}; \\
\node {4}; &
\node
{9}; &
\node
{2}; \\
};
\draw [<->,red,thick] (a.center) -- (b.center) node [above,midway] {11mm};
\end{tikzpicture}
10mm 10mm
8
1
6
3
5
7
4
9
2
\begin{tikzpicture}
\matrix [draw,nodes=draw,column sep={1cm,between origins}]
{
\node (a) {8}; & \node (b) {1}; &[between borders] \node (c) {6}; \\
\node
{3}; & \node
{5}; &
\node
{7}; \\
\node
{4}; & \node
{9}; &
\node
{2}; \\
};
\draw [<->,red,thick] (a.center) -- (b.center) node [above,midway] {10mm};
\draw [<->,red,thick] (b.east) -- (c.west) node [above,midway] {10mm};
\end{tikzpicture}
8
3
4
20.3.3
Cell Styles and Options
The following styles and options are useful for changing the appearance of all cell pictures:
/tikz/every cell={hrow i}{hcolumni}
(style, no default, initially empty)
This style is installed at the beginning of each cell picture with the two parameters being the current
hrow i and hcolumni of the cell. Note that setting this style to draw will not cause all nodes to be drawn
since the draw option has to be passed to each node individually.
Inside this style (and inside all cells), the current hrow i and hcolumni number are also accessible via the
counters \pgfmatrixcurrentrow and \pgfmatrixcurrentcolumn.
(no default)
/tikz/cells=hoptionsi
This key adds the hoptionsi to the style every cell. It is mainly just a shorthand for the code
every cell/.append style=hoptionsi.
(no default)
/tikz/nodes=hoptionsi
This key adds the hoptionsi to the style every node. It is mainly just a shorthand for the code
every node/.append style=hoptionsi.
The main use of this option is the install some options for the nodes inside the matrix that should not
apply to the matrix itself.
8 1 6
3 5 7
4 9 2
\begin{tikzpicture}
\matrix [nodes={fill=blue!20,minimum size=5mm}]
{
\node {8}; & \node{1}; & \node {6}; \\
\node {3}; & \node{5}; & \node {7}; \\
\node {4}; & \node{9}; & \node {2}; \\
};
\end{tikzpicture}
The next set of styles can be used to change the appearance of certain rows, columns, or cells. If more
than one of these styles is defined, they are executed in the below order (the every cell style is executed
before all of the below).
/tikz/column hnumber i
(style, no value)
This style is used for every cell in column hnumber i.
(style, no value)
/tikz/every odd column
This style is used for every cell in an odd column.
(style, no value)
/tikz/every even column
This style is used for every cell in an even column.
309
/tikz/row hnumber i
(style, no value)
This style is used for every cell in row hnumber i.
(style, no value)
/tikz/every odd row
This style is used for every cell in an odd row.
(style, no value)
/tikz/every even row
This style is used for every cell in an even row.
/tikz/row hrow number i column hcolumn number i
(style, no value)
This style is used for the cell in row hrow number i and column hcolumn number i.
8 1 6
3 5 7
4 9 2
\begin{tikzpicture}
[row 1/.style={red},
column 2/.style={green!50!black},
row 3 column 3/.style={blue}]
\matrix
{
\node {8}; & \node{1}; & \node {6}; \\
\node {3}; & \node{5}; & \node {7}; \\
\node {4}; & \node{9}; & \node {2}; \\
};
\end{tikzpicture}
You can use the column hnumber i option to change the alignment for different columns.
123 456 789
12
45 78
1
4 7
\begin{tikzpicture}
[column 1/.style={anchor=base west},
column 2/.style={anchor=base east},
column 3/.style={anchor=base}]
\matrix
{
\node {123}; & \node{456}; & \node {789}; \\
\node {12}; & \node{45}; & \node {78}; \\
\node {1}; & \node{4}; & \node {7}; \\
};
\end{tikzpicture}
In many matrices all cell pictures have nearly the same code. For example, cells typically start with
\node{ and end };. The following options allow you to execute such code in all cells:
(no default)
/tikz/execute at begin cell=hcodei
The code will be executed at the beginning of each nonempty cell.
(no default)
/tikz/execute at end cell=hcodei
The code will be executed at the end of each nonempty cell.
(no default)
/tikz/execute at empty cell=hcodei
The code will be executed inside each empty cell.
8 1 6
3 5 7
4 9 2
\begin{tikzpicture}
[matrix of nodes/.style={
execute at begin cell=\node\bgroup,
execute at end cell=\egroup;%
}]
\matrix [matrix of nodes]
{
8 & 1 & 6 \\
3 & 5 & 7 \\
4 & 9 & 2 \\
};
\end{tikzpicture}
310
8 1 –
3 – 7
– – 2
\begin{tikzpicture}
[matrix of nodes/.style={
execute at begin cell=\node\bgroup,
execute at end cell=\egroup;,%
execute at empty cell=\node{--};%
}]
\matrix [matrix of nodes]
{
8 & 1 &
\\
3 &
& 7 \\
&
& 2 \\
};
\end{tikzpicture}
The matrix library defines a number of styles that make use of the above options.
20.4
Anchoring a Matrix
Since matrices are nodes, they can be anchored in the usual fashion using the anchor option. However, there
are two ways to influence this placement further. First, the following option is often useful:
/tikz/matrix anchor=hanchor i
(no default)
This option has the same effect as anchor, but the option applies only to the matrix itself, not to the
cells inside. If you just say anchor=north as an option to the matrix node, all nodes inside matrix will
also have this anchor, unless it is explicitly set differently for each node. By comparison, matrix anchor
sets the anchor for the matrix, but for the nodes inside the value of anchor remain unchanged.
123
12
1
123
12
1
\begin{tikzpicture}
\matrix [matrix anchor=west] at (0,0)
{
\node {123}; \\ % still center anchor
\node {12}; \\
\node {1}; \\
};
\matrix [anchor=west] at (0,-2)
{
\node {123}; \\ % inherited west anchor
\node {12}; \\
\node {1}; \\
};
\end{tikzpicture}
The second way to anchor a matrix is to use an anchor of a node inside the matrix. For this, the anchor
option has a special effect when given as an argument to a matrix:
/tikz/anchor=hanchor or node.anchor i
(no default)
Normally, the argument of this option refers to anchor of the matrix node, which is the node that includes
all of the stuff of the matrix. However, you can also provide an argument of the form hnodei.hanchor i
where hnodei must be node defined inside the matrix and hanchor i is an anchor of this node. In this
case, the whole matrix is shifted around in such a way that this particular anchor of this particular node
lies at the at position of the matrix. The same is true for matrix anchor.
a b c d
a b c d
a b c d
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\matrix[matrix anchor=inner node.south,anchor=base,row sep=3mm]
{
\node {a}; & \node
{b}; & \node {c}; & \node {d};
\node {a}; & \node(inner node) {b}; & \node {c}; & \node {d};
\node {a}; & \node
{b}; & \node {c}; & \node {d};
};
\draw (inner node.south) circle (1pt);
\end{tikzpicture}
311
at (1,1)
\\
\\
\\
20.5
Considerations Concerning Active Characters
Even though Tik Z seems to use & to separate cells, pgf actually uses a different command to separate cells,
namely the command \pgfmatrixnextcell and using a normal & character will normally fail. What happens
is that, Tik Z makes & an active character and then defines this character to be equal to \pgfmatrixnextcell.
In most situations this will work nicely, but sometimes & cannot be made active; for instance because the
matrix is used in an argument of some macro or the matrix contains nodes that contain normal {tabular}
environments. In this case you can use the following option to avoid having to type \pgfmatrixnextcell
each time:
/tikz/ampersand replacement=hmacro name or emptyi
(no default)
If a macro name is provided, this macro will be defined to be equal to \pgfmatrixnextcell inside
matrices and & will not be made active. For instance, you could say ampersand replacement=\& and
then use \& to separate columns as in the following example:
Hello
20.6
\tikz
\matrix [ampersand replacement=\&]
{
\draw (0,0)
circle (4mm); \& \node[rotate=10] {Hello};
\\
\draw (0.2,0) circle (2mm); \& \fill[red]
(0,0) circle (3mm); \\
};
Examples
The following examples are adapted from code by Mark Wibrow. The first two redraw pictures from Timothy
van Zandt’s PStricks documentation:
U
x
y
X ×Z Y
p
X
q
f
Y
Z
g
\begin{tikzpicture}
\matrix [matrix of math nodes,row sep=1cm]
{
|(U)| U &[2mm]
&[8mm]
\\
&
|(XZY)| X \times_Z Y &
|(X)| X \\
&
|(Y)|
Y
&
|(Z)| Z \\
};
\begin{scope}[every node/.style={midway,auto,font=\scriptsize}]
\draw [double, dashed] (U)
-- node {$x$} (X);
\draw
(X)
-- node {$p$} (X -| XZY.east)
(X)
-- node {$f$} (Z)
-- node {$g$} (Y)
-- node {$q$} (XZY)
-- node {$y$} (U);
\end{scope}
\end{tikzpicture}
A
f
e
g
B
b
a
E
C
b
c
D
312
\begin{tikzpicture}[>=stealth,->,shorten >=2pt,looseness=.5,auto]
\matrix [matrix of math nodes,
column sep={2cm,between origins},
row sep={3cm,between origins},
nodes={circle, draw, minimum size=7.5mm}]
{
& |(A)| A &
\\
|(B)| B & |(E)| E & |(C)| C \\
& |(D)| D
\\
};
\begin{scope}[every node/.style={font=\small\itshape}]
\draw (A) to [bend left] node [midway]
{g} (B);
\draw (B) to [bend left] node [midway]
{f} (A);
\draw (D) -node [midway]
{c} (B);
\draw (E) -node [midway]
{b} (B);
\draw (E) -node [near end] {a} (C);
\draw [-,line width=8pt,draw=graphicbackground]
(D) to [bend right, looseness=1] (A);
\draw (D) to [bend right, looseness=1]
node [near start] {b} node [near end] {e} (A);
\end{scope}
\end{tikzpicture}
\begin{tikzpicture}
\matrix (network)
[matrix of nodes,%
nodes in empty cells,
nodes={outer sep=0pt,circle,minimum size=4pt,draw},
column sep={1cm,between origins},
row sep={1cm,between origins}]
{
&
&
& \\
&
&
& \\
|[draw=none]| & |[xshift=1mm]| & |[xshift=-1mm]|
\\
};
\foreach \a in {1,...,4}{
\draw (network-3-2) -- (network-2-\a);
\draw (network-3-3) -- (network-2-\a);
\draw [-stealth] ([yshift=5mm]network-1-\a.north) -- (network-1-\a);
\foreach \b in {1,...,4}
\draw (network-1-\a) -- (network-2-\b);
}
\draw [stealth-] ([yshift=-5mm]network-3-2.south) -- (network-3-2);
\draw [stealth-] ([yshift=-5mm]network-3-3.south) -- (network-3-3);
\end{tikzpicture}
The following example is adapted from code written by Kjell Magne Fauske, which is based on the following paper: K. Bossley, M. Brown, and C. Harris, Neurofuzzy identification of an autonomous underwater
vehicle, International Journal of Systems Science, 1999, 30, 901–913.
313
initialize
model
expert
system
identify
candidate
model
update
model
yes
evaluate
candidate
models
is best
candidate
no
stop
314
\begin{tikzpicture}
[auto,
decision/.style={diamond, draw=blue, thick, fill=blue!20,
text width=4.5em,align=flush center,
inner sep=1pt},
block/.style
={rectangle, draw=blue, thick, fill=blue!20,
text width=5em,align=center, rounded corners,
minimum height=4em},
line/.style
={draw, thick, -latex’,shorten >=2pt},
cloud/.style
={draw=red, thick, ellipse,fill=red!20,
minimum height=2em}]
\matrix [column sep=5mm,row sep=7mm]
{
% row 1
\node [cloud] (expert)
{expert}; &
\node [block] (init)
{initialize model}; &
\node [cloud] (system)
{system}; \\
% row 2
& \node [block] (identify) {identify candidate model}; & \\
% row 3
\node [block] (update)
{update model}; &
\node [block] (evaluate) {evaluate candidate models}; & \\
% row 4
& \node [decision] (decide) {is best candidate}; & \\
% row 5
& \node [block] (stop)
{stop}; & \\
};
\begin{scope}[every path/.style=line]
\path
(init)
-- (identify);
\path
(identify) -- (evaluate);
\path
(evaluate) -- (decide);
\path
(update)
|- (identify);
\path
(decide)
-| node [near start] {yes} (update);
\path
(decide)
-- node [midway] {no} (stop);
\path [dashed] (expert)
-- (init);
\path [dashed] (system)
-- (init);
\path [dashed] (system)
|- (evaluate);
\end{scope}
\end{tikzpicture}
315
21
Making Trees Grow
21.1
Introduction to the Child Operation
Trees are a common way of visualizing hierarchical structures. A simple tree looks like this:
root
left
right
child child
\begin{tikzpicture}
\node {root}
child {node {left}}
child {node {right}
child {node {child}}
child {node {child}}
};
\end{tikzpicture}
Admittedly, in reality trees are more likely to grow upward and not downward as above. You can tell
whether the author of a paper is a mathematician or a computer scientist by looking at the direction their
trees grow. A computer scientist’s trees will grow downward while a mathematician’s tree will grow upward.
Naturally, the correct way is the mathematician’s way, which can be specified as follows:
child child
left
right
root
\begin{tikzpicture}
\node {root} [grow’=up]
child {node {left}}
child {node {right}
child {node {child}}
child {node {child}}
};
\end{tikzpicture}
In Tik Z, there are two ways of specifying trees: Using either the graph path operation, which is covered
in Section 19, or using the child path operation, which is covered in the present section. Both methods
have their advantages.
In Tik Z, trees are specified by adding children to a node on a path using the child operation:
\path . . . child[hoptionsi]foreachhvariablesiin{hvaluesi}{hchild pathi} . . . ;
This operation should directly follow a completed node operation or another child operation, although
it is permissible that the first child operation is preceded by options (we will come to that).
When a node operation like node {X} is followed by child, Tik Z starts counting the number of child
nodes that follow the original node {X}. For this, it scans the input and stores away each child and
its arguments until it reaches a path operation that is not a child. Note that this will fix the character
codes of all text inside the child arguments, which means, in essence, that you cannot use verbatim text
inside the nodes inside a child. Sorry.
Once the children have been collected and counted, Tik Z starts generating the child nodes. For each
child of a parent node Tik Z computes an appropriate position where the child is placed. For each child,
the coordinate system is transformed so that the origin is at this position. Then the hchild pathi is
drawn. Typically, the child path just consists of a node specification, which results in a node being
drawn at the child’s position. Finally, an edge is drawn from the first node in the hchild pathi to the
parent node.
The optional foreach part (note that there is no backslash before foreach) allows you to specify
multiple children in a single child command. The idea is the following: A \foreach statement is
(internally) used to iterate over the list of hvaluesi. For each value in this list, a new child is added to
the node. The syntax for hvariablesi and for hvaluesi is the same as for the \foreach statement, see
Section 83. For example, when you say
node {root} child [red] foreach \name in {1,2} {node {\name}}
the effect will be the same as if you had said
node {root} child[red] {node {1}} child[red] {node {2}}
When you write
node {root} child[\pos] foreach \name/\pos in {1/left,2/right} {node[\pos] {\name}}
the effect will be the same as for
316
node {root} child[left] {node[left] {1}} child[right] {node[right] {2}}
You can nest things as in the following example:
\begin{tikzpicture}
[level distance=4mm,level/.style={sibling distance=8mm/#1}]
\coordinate
child foreach \x in {0,1}
{child foreach \y in {0,1}
{child foreach \z in {0,1}}};
\end{tikzpicture}
The details and options for this operation are described in the rest of this present section.
21.2
Child Paths and Child Nodes
For each child of a root node, its hchild pathi is inserted at a specific location in the picture (the placement
rules are discussed in Section 21.5). The first node in the hchild pathi, if it exists, is special and called
the child node. If there is no first node in the hchild pathi, that is, if the hchild pathi is missing (including
the curly braces) or if it does not start with node or with coordinate, then an empty child node of shape
coordinate is automatically added.
Consider the example \node {x} child {node {y}} child;. For the first child, the hchild pathi has
the child node node {y}. For the second child, no child node is specified and, thus, it is just coordinate.
As for any normal node, you can give the child node a name, shift it around, or use options to influence
how it is rendered.
root
right
left
\begin{tikzpicture}[sibling distance=15mm]
\node[rectangle,draw] {root}
child {node[circle,draw,yshift=-5mm] (left node) {left}}
child {node[ellipse,draw] (right node) {right}};
\draw[dashed,->] (left node) -- (right node);
\end{tikzpicture}
In many cases, the hchild pathi will just consist of a specification of a child node and, possibly, children
of this child node. However, the node specification may be followed by arbitrary other material that will be
added to the picture, transformed to the child’s coordinate system. For your convenience, a move-to (0,0)
operation is inserted automatically at the beginning of the path. Here is an example:
root
\begin{tikzpicture}
\node {root}
child {[fill] circle (2pt)}
child {[fill] circle (2pt)};
\end{tikzpicture}
At the end of the hchild pathi you may add a special path operation called edge from parent. If this
operation is not given by yourself somewhere on the path, it will be automatically added at the end. This
option causes a connecting edge from the parent node to the child node to be added to the path. By
giving options to this operation you can influence how the edge is rendered. Also, nodes following the
edge from parent operation will be placed on this edge, see Section 21.6 for details.
To sum up:
1. The child path starts with a node specification. If it is not there, it is added automatically.
2. The child path ends with a edge from parent operation, possibly followed by nodes to be put on this
edge. If the operation is not given at the end, it is added automatically.
21.3
Naming Child Nodes
Child nodes can be named like any other node using either the name option or the special syntax in which
the name of the node is placed in round parentheses between the node operation and the node’s text.
If you do not assign a name to a child node, Tik Z will automatically assign a name as follows: Assume
that the name of the parent node is, say, parent. (If you did not assign a name to the parent, Tik Z will do
so itself, but that name will not be user-accessible.) The first child of parent will be named parent-1, the
second child is named parent-2, and so on.
317
This naming convention works recursively. If the second child parent-2 has children, then the first of
these children will be called parent-2-1 and the second parent-2-2 and so on.
If you assign a name to a child node yourself, no name is generated automatically (the node does not have
two names). However, “counting continues,” which means that the third child of parent is called parent-3
independently of whether you have assigned names to the first and/or second child of parent.
Here is an example:
root
root-1
root-2
special
21.4
root-2-2
\begin{tikzpicture}[sibling distance=15mm]
\node (root) {root}
child
child {
child {coordinate (special)}
child
};
\node at (root-1) {root-1};
\node at (root-2) {root-2};
\node at (special) {special};
\node at (root-2-2) {root-2-2};
\end{tikzpicture}
Specifying Options for Trees and Children
Each child may have its own hoptionsi, which apply to “the whole child,” including all of its grandchildren.
Here is an example:
\begin{tikzpicture}
[thick,level 1/.style={sibling distance=15mm},
level 2/.style={sibling distance=10mm}]
\coordinate
child[red]
{child child}
child[green] {child child[blue]};
\end{tikzpicture}
The options of the root node have no effect on the children since the options of a node are always “local”
to that node. Because of this, the edges in the following tree are black, not red.
root
\begin{tikzpicture}[thick]
\node [red] {root}
child
child;
\end{tikzpicture}
This raises the problem of how to set options for all children. Naturally, you could always set options for
the whole path as in \path [red] node {root} child child; but this is bothersome in some situations.
Instead, it is easier to give the options before the first child as follows:
root
\begin{tikzpicture}[thick]
\node [red] {root}
[green] % option applies to all children
child
child;
\end{tikzpicture}
Here is the set of rules:
1. Options for the whole tree are given before the root node.
2. Options for the root node are given directly to the node operation of the root.
3. Options for all children can be given between the root node and the first child.
4. Options applying to a specific child path are given as options to the child operation.
5. Options applying to the node of a child, but not to the whole child path, are given as options to the
node command inside the hchild pathi.
318
\begin{tikzpicture}
\scoped
[...]
\node[...] {root}
[...]
child[...]
{
node[...] {}
...
}
child[...]
;
\end{tikzpicture}
%
%
%
%
Options
Options
Options
Options
apply
apply
apply
apply
to
to
to
to
the whole tree
the root node only
all children
this child and all its children
% Options apply to the child node only
% Options apply to this child and all its children
There are additional styles that influence how children are rendered:
(style, initially empty)
/tikz/every child
This style is used at the beginning of each child, as if you had given the style’s contents as options to
the child operation.
(style, initially empty)
/tikz/every child node
This style is used at the beginning of each child node in addition to the every node style.
/tikz/level=hnumber i
(style, no default, initially empty)
This style is executed at the beginning of each set of children, where hnumber i is the current level in
the current tree. For example, when you say \node {x} child child;, then level=1 is used before
the first child. The style or code of this key will be passed hnumber i as its first parameter. If this first
child has children itself, then level=2 would be used for them.
root
\begin{tikzpicture}[level/.style={sibling distance=20mm/#1}]
\node {root}
child { child child }
child { child child child };
\end{tikzpicture}
/tikz/level hnumber i
(style, initially empty)
This style is used in addition to the level style. So, when you say \node {x} child child;, then the
following key list is executed: level=1,level 1.
root
21.5
21.5.1
\begin{tikzpicture}
[level 1/.style={sibling distance=20mm},
level 2/.style={sibling distance=5mm}]
\node {root}
child { child child }
child { child child child };
\end{tikzpicture}
Placing Child Nodes
Basic Idea
Perhaps the most difficult part in drawing a tree is the correct layout of the children. Typically, the children
have different sizes and it is not easy to arrange them in such a manner that not too much space is wasted, the
children do not overlap, and they are either evenly spaced or their centers are evenly distributed. Calculating
good positions is especially difficult since a good position for the first child may depend on the size of the
last child.
In basic Tik Z, when you do not make use of the graph drawing facilities explained in Part IV, a comparatively simple approach is taken to placing the children. In order to compute a child’s position, all that
is taken into account is the number of the current child in the list of children and the number of children in
this list. Thus, if a node has five children, then there is a fixed position for the first child, a position for the
second child, and so on. These positions do not depend on the size of the children and, hence, children can
319
easily overlap. However, since you can use options to shift individual children a bit, this is not as great a
problem as it may seem.
Although the placement of the children only depends on their number in the list of children and the
total number of children, everything else about the placement is highly configurable. You can change the
distance between children (appropriately called the sibling distance) and the distance between levels of
the tree. These distances may change from level to level. The direction in which the tree grows can be
changed globally and for parts of the tree. You can even specify your own “growth function” to arrange
children on a circle or along special lines or curves.
21.5.2
Default Growth Function
The default growth function works as follows: Assume that we are given a node and five children. These
children will be placed on a line with their centers (or, more generally, with their anchors) spaced apart by
the current sibling distance. The line is orthogonal to the current direction of growth, which is set with
the grow and grow’ option (the latter option reverses the ordering of the children). The distance from the
line to the parent node is given by the level distance.
4
sibling
distanc
e
3
level
root distance
2
1
\begin{tikzpicture}[sibling distance=15mm, level distance=15mm]
\path [help lines]
node (root) {root}
[grow=-10]
child {node {1}}
child {node {2}}
child {node {3}}
child {node {4}};
\draw[|<->|,thick] (root-1.center)
-- node[above,sloped] {sibling distance} (root-2.center);
\draw[|<->|,thick] (root.center)
-- node[above,sloped] {level distance} +(-10:\tikzleveldistance);
\end{tikzpicture}
(no default, initially 15mm)
/tikz/level distance=hdistancei
This key determines the distance between different levels of the tree, more precisely, between the parent
and the line on which its children are arranged. When given to a single child, this will set the distance
for this child only.
root
\begin{tikzpicture}
\node {root}
[level distance=20mm]
child
child {
[level distance=5mm]
child
child
child
}
child[level distance=10mm];
\end{tikzpicture}
root
\begin{tikzpicture}
[level 1/.style={level distance=10mm},
level 2/.style={level distance=5mm}]
\node {root}
child
child {
child
child[level distance=10mm]
child
}
child;
\end{tikzpicture}
320
(no default, initially 15mm)
/tikz/sibling distance=hdistancei
This key specifies the distance between the anchors of the children of a parent node.
\begin{tikzpicture}
[level distance=4mm,
level 1/.style={sibling distance=8mm},
level 2/.style={sibling distance=4mm},
level 3/.style={sibling distance=2mm}]
\coordinate
child {
child {child child}
child {child child}
}
child {
child {child child}
child {child child}
};
\end{tikzpicture}
31
30
20
20
10
19
18
5 4 9 1 1
\begin{tikzpicture}
[level distance=10mm,
every node/.style={fill=red!60,circle,inner sep=1pt},
level 1/.style={sibling distance=20mm,nodes={fill=red!45}},
level 2/.style={sibling distance=10mm,nodes={fill=red!30}},
level 3/.style={sibling distance=5mm,nodes={fill=red!25}}]
\node {31}
child {node {30}
child {node {20}
child {node {5}}
child {node {4}}
}
child {node {10}
child {node {9}}
child {node {1}}
}
}
child {node {20}
child {node {19}
child {node {1}}
child[missing]
}
child {node {18}}
};
\end{tikzpicture}
(no default)
/tikz/grow=hdirectioni
This key is used to define the hdirectioni in which the tree will grow. The hdirectioni can either be
an angle in degrees or one of the following special text strings: down, up, left, right, north, south,
east, west, north east, north west, south east, and south west. All of these have “their obvious
meaning,” so, say, south west is the same as the angle −135◦ .
As a side effect, this option installs the default growth function.
In addition to setting the direction, this option also has a seemingly strange effect: It sets the sibling
distance for the current level to 0pt, but leaves the sibling distance for later levels unchanged.
This somewhat strange behaviour has a highly desirable effect: If you give this option before the list
of children of a node starts, the “current level” is still the parent level. Each child will be on a later
level and, hence, the sibling distance will be as specified originally. This will cause the children to be
neatly aligned in a line orthogonal to the given hdirectioni. However, if you give this option locally to a
single child, then “current level” will be the same as the child’s level. The zero sibling distance will then
cause the child to be placed exactly at a point at distance level distance in the direction hdirectioni.
However, the children of the child will be placed “normally” on a line orthogonal to the hdirectioni.
These placement effects are best demonstrated by some examples:
\tikz \node {root} [grow=right] child child;
root
321
root
\begin{tikzpicture}[level distance=10mm,sibling distance=5mm]
\node {root}
[grow=down]
child
child
child[grow=right] {
child child child
};
\end{tikzpicture}
root
H
\tikz \node {root} [grow=south west] child child;
H
H
C
C
H
H
H
This is wrong!
the middle is here
end
\begin{tikzpicture}[level distance=2em]
\node {C}
child[grow=up]
{node {H}}
child[grow=left] {node {H}}
child[grow=down] {node {H}}
child[grow=right] {node {C}
child[grow=up]
{node {H}}
child[grow=right] {node {H}}
child[grow=down] {node {H}}
edge from parent[double]
coordinate (wrong)
};
\draw[<-,red] ([yshift=-2mm]wrong) -- +(0,-1)
node[below]{This is wrong!};
\end{tikzpicture}
\begin{tikzpicture}
\node[rectangle,draw] (a) at (0,0) {start node};
\node[rectangle,draw] (b) at (2,1) {end};
\draw (a) -- (b)
node[coordinate,midway] {}
child[grow=100,<-] {node[above] {the middle is here}};
\end{tikzpicture}
start node
(no default)
/tikz/grow’=hdirectioni
This key has the same effect as grow, only the children are arranged in the opposite order.
21.5.3
Missing Children
Sometimes one or more of the children of a node are “missing.” Such a missing child will count as a child
with respect to the total number of children and also with respect to the current child count, but it will not
be rendered.
/tikz/missing=htrue or falsei
(default true)
If this option is given to a child, the current child counter is increased, but the child is otherwise ignored.
In particular, the normal contents of the child is completely ignored.
root
1 2 3
5 6
\begin{tikzpicture}[level distance=10mm,sibling distance=5mm]
\node {root} [grow=down]
child
{ node {1} }
child
{ node {2} }
child
{ node {3} }
child[missing] { node {4} }
child
{ node {5} }
child
{ node {6} };
\end{tikzpicture}
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21.5.4
Custom Growth Functions
/tikz/growth parent anchor=hanchor i
(no default, initially center)
This key allows you to specify which anchor of the parent node is to be used for computing the children’s
position. For example, when there is only one child and the level distance is 2cm, then the child
node will be placed two centimeters below the hanchor i of the parent node. “Being placed” means that
the child node’s anchor (which is the anchor specified using the anchor= option in the node command
of the child) is two centimeters below the parent node’s hanchor i.
In the following example, the two red lines both have length 1cm.
root
root
\begin{tikzpicture}[level distance=1cm]
\node [rectangle,draw] (a) at (0,0) {root}
[growth parent anchor=south] child;
\node [rectangle,draw] (b) at (2,0) {root}
[growth parent anchor=north east] child;
\draw [red,thick,dashed] (a.south) -- (a-1);
\draw [red,thick,dashed] (b.north east) -- (b-1);
\end{tikzpicture}
In the next example, the top and bottom nodes are aligned at the top and the bottom, respectively.
root
big root
small
big
\begin{tikzpicture}
[level distance=2cm,growth parent anchor=north,
every node/.style={anchor=north,rectangle,draw}
every child node/.style={anchor=south}]
\node at (0,0) {root} child {node {small}};
\node at (2,0) {big root} child {node {\large big}};
\end{tikzpicture}
/tikz/growth function=hmacro namei
(no default, initially an internal function)
This rather low-level option allows you to set a new growth function. The hmacro namei must be the
name of a macro without parameters. This macro will be called for each child of a node. The initial
function is an internal function that corresponds to downward growth.
The effect of executing the macro should be the following: It should transform the coordinate system
in such a way that the origin becomes the place where the current child should be anchored. When the
macro is called, the current coordinate system will be set up such that the anchor of the parent node
is in the origin. Thus, in each call, the hmacro namei must essentially do a shift to the child’s origin.
When the macro is called, the TEX counter \tikznumberofchildren will be set to the total number of
children of the parent node and the counter \tikznumberofcurrentchild will be set to the number of
the current child.
The macro may, in addition to shifting the coordinate system, also transform the coordinate system
further. For example, it could be rotated or scaled.
Additional growth functions are defined in the library, see Section 72.
21.6
Edges From the Parent Node
Every child node is connected to its parent node via a special kind of edge called the edge from parent.
This edge is added to the hchild pathi when the following path operation is encountered:
\path . . . edge from parent[hoptionsi] . . . ;
This path operation can only be used inside hchild pathsi and should be given at the end, possibly
followed by hnode specificationsi like node {a}. If a hchild pathi does not contain this operation, it will
be added at the end of the hchild pathi automatically.
By default, this operation does the following:
1. The following style is executed:
323
(style, initially draw)
/tikz/edge from parent
This style is inserted right before the edge from parent path and before the hoptionsi are
inserted.
root
left
right
child child
\begin{tikzpicture}
[edge from parent/.style={draw,red,thick}]
\node {root}
child {node {left} edge from parent[dashed]}
child {node {right}
child {node {child}}
child {node {child} edge from parent[draw=none]}
};
\end{tikzpicture}
2. Next, the hoptionsi are executed.
3. Next, the text stored in the following key is inserted:
(no default, initially code shown below)
/tikz/edge from parent path=hpathi
This option allows you to set the edge from parent path to a new path. Initially, this path
is the following:
(\tikzparentnode\tikzparentanchor) -- (\tikzchildnode\tikzchildanchor)
The \tikzparentnode is a macro that will expand to the name of the parent node. This
works even when you have not assigned a name to the parent node, in this case an internal
name is automatically generated. The \tikzchildnode is a macro that expands to the name
of the child node. The two ...anchor macros are empty by default. So, what is essentially
inserted is just the path segment (\tikzparentnode) --(\tikzchildnode); which is exactly
an edge from the parent to the child.
You can modify this edge from parent path to achieve all sorts of effects. For example, we
could replace the straight line by a curve as follows:
root
right
left
child
child
\begin{tikzpicture}[level distance=15mm, sibling distance=15mm,
edge from parent path=
{(\tikzparentnode.south) .. controls +(0,-1) and +(0,1)
.. (\tikzchildnode.north)}]
\node {root}
child {node {left}}
child {node {right}
child {node {child}}
child {node {child}}
};
\end{tikzpicture}
Further useful edge from parent paths are defined in the tree library, see Section 72.
The nodes in a hnode specificationi following the edge from parent path command get executed as if the pos option had been added to all these nodes, see also Section 17.8.
As an example, consider the following code:
\node (root) {} child {node (child) {} edge to parent node {label}};
The edge to parent operation and the following node operation will, together, have the same
effect as if we had said:
(root) -- (child) node [pos=0.5] {label}
Here is a more complicated example:
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root
a bx
left right
c
child child
\begin{tikzpicture}
\node {root}
child {
node {left}
edge from parent
node[left] {a}
node[right] {b}
}
child {
node {right}
child {
node {child}
edge from parent
node[left] {c}
}
child {node {child}}
edge from parent
node[near end] {x}
};
\end{tikzpicture}
As said before, the anchors in the default edge from parent path are empty. However, you
can set them using the following keys:
/tikz/child anchor=hanchor i
(no default, initially border)
Specifies the anchor where the edge from parent meets the child node by setting the macro
\tikzchildanchor to .hanchor i.
If you specify border as the hanchor i, then the macro \tikzchildanchor is set to the
empty string. The effect of this is that the edge from the parent will meet the child on
the border at an automatically calculated position.
root
left
right
child child
\begin{tikzpicture}
\node {root}
[child anchor=north]
child {node {left} edge from parent[dashed]}
child {node {right}
child {node {child}}
child {node {child} edge from parent[draw=none]}
};
\end{tikzpicture}
/tikz/parent anchor=hanchor i
(no default, initially border)
This option works the same way as the child anchor, only for the parent.
All of the above describes the standard functioning of the edge from parent command. You may, however, sometimes need even more fine-grained control (the graph drawing engine needs it, for instance).
In such cases the following key gives you complete control:
(no default)
/tikz/edge from parent macro=hmacroi
The hmacroi gets expanded each time the edge from parent path operation is used. This hmacroi
must take two parameters and must expand to some text that is subsequently parsed by the
parser. The first parameter will be the set of hoptionsi that where passed to the edge from parent
command, the second parameter will be the hnode specificationsi that following the command.
The standard behaviour of drawing a straight line from the parent node to the child node could be
achieved by setting the hmacroi to the following:
\def\mymacro#1#2{
[style=edge from parent, #1]
(\tikzparentnode\tikzparentanchor) -- #2 (\tikzchildnode\tikzchildanchor)
}
Note that #2 is placed between -- and the node to ensure that nodes are put “on top” of the line.
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22
Plots of Functions
A warning before we get started: If you are looking for an easy way to create a normal plot of a function with
scientific axes, ignore this section and instead look at the pgfplots package or at the datavisualization
command from Part VI.
22.1
Overview
Tik Z can be used to create plots of functions, a job that is normally handled by powerful programs like
gnuplot or mathematica. These programs can produce two different kinds of output: First, they can
output a complete plot picture in a certain format (like pdf) that includes all low-level commands necessary
for drawing the complete plot (including axes and labels). Second, they can usually also produce “just plain
data” in the form of a long list of coordinates. Most of the powerful programs consider it a to be “a bit
boring” to just output tabled data and very much prefer to produce fancy pictures. Nevertheless, when
coaxed, they can also provide the plain data.
The advantage of creating plots directly using Tik Z is consistency: Plots created using Tik Z will automatically have the same styling and fonts as those used in the rest of a document – something that is hard to
do right when an external program gets involved. Other problems people encounter with external programs
include: Formulas will look different, if they can be rendered at all; line widths will usually be too thick
or too thin; scaling effects upon inclusion can create a mismatch between sizes in the plot and sizes in the
text; the automatic grid generated by most programs is mostly distracting; the automatic ticks generated
by most programs are cryptic numerics (try adding a tick reading “π” at the right point); most programs
make it very easy to create “chart junk” in a most convenient fashion; arrows and plot marks will almost
never match the arrows used in the rest of the document. This list is not exhaustive, unfortunately.
There are basically three ways of creating plots using Tik Z:
1. Use the plot path operation. How this works is explained in the present section. This is the most
“basic” of the three options and forces you to do a lot of things “by hand” like adding axes or ticks.
2. Use the datavisualization path command, which is documented in Part VI. This command is much
more powerful than the plot path operation and produces complete plots including axes and ticks.
The downside is that you cannot use it to “just” quickly plot a simple curve (or, more precisely, it is
hard to use it in this way).
3. Use the pgfplots package, which is basically an alternative to the datavisualization command.
While the underlying philosophy of this package is not as “ambitious” as that of the command
datavisualization, it is somewhat more mature, has a simpler design, and wider support base.
22.2
The Plot Path Operation
The plot path operation can be used to append a line or curve to the path that goes through a large number
of coordinates. These coordinates are either given in a simple list of coordinates, read from some file, or
they are computed on the fly.
The syntax of the plot comes in different versions.
\path . . . --plothfurther argumentsi . . . ;
This operation plots the curve through the coordinates specified in the hfurther argumentsi. The current
(sub)path is simply continued, that is, a line-to operation to the first point of the curve is implicitly
added. The details of the hfurther argumentsi will be explained in a moment.
\path . . . plothfurther argumentsi . . . ;
This operation plots the curve through the coordinates specified in the hfurther argumentsi by first
“moving” to the first coordinate of the curve.
The hfurther argumentsi are used in different ways to specifying the coordinates of the points to be
plotted:
1. --plot[hlocal optionsi]coordinates{hcoordinate 1 ihcoordinate 2 i. . . hcoordinate ni}
2. --plot[hlocal optionsi]file{hfilenamei}
326
3. --plot[hlocal optionsi]hcoordinate expressioni
4. --plot[hlocal optionsi]function{hgnuplot formulai}
These different ways are explained in the following.
22.3
Plotting Points Given Inline
Points can be given directly in the TEX-file as in the following example:
\tikz \draw plot coordinates {(0,0) (1,1) (2,0) (3,1) (2,1) (10:2cm)};
Here is an example showing the difference between plot and --plot:
\begin{tikzpicture}
\draw (0,0) -- (1,1) plot coordinates {(2,0) (4,0)};
\draw[color=red,xshift=5cm]
(0,0) -- (1,1) -- plot coordinates {(2,0) (4,0)};
\end{tikzpicture}
22.4
Plotting Points Read From an External File
The second way of specifying points is to put them in an external file named hfilenamei. Currently, the only
file format that Tik Z allows is the following: Each line of the hfilenamei should contain one line starting
with two numbers, separated by a space. A line may also be empty or, if it starts with # or % it is considered
empty. For such lines, a “new data set” is started, typically resulting in a new subpath being started in the
plot (see Section 107.2.2 on how to change this behaviour, if necessary). For lines containing two numbers,
they must be separated by a space. They may be following by arbitrary text, which is ignored, except if
it is o or u. In the first case, the point is considered to be an outlier and normally also results in a new
subpath being started. In the second case, the point is considered to be undefined, which also results in a
new subpath being started. Again, see Section 107.2.2 on how to change this, if necessary. (This is exactly
the format that gnuplot produces when you say set terminal table.)
\tikz \draw plot[mark=x,smooth] file {plots/pgfmanual-sine.table};
The file plots/pgfmanual-sine.table reads:
#Curve 0, 20 points
#x y type
0.00000 0.00000 i
0.52632 0.50235 i
1.05263 0.86873 i
1.57895 0.99997 i
...
9.47368 -0.04889 i
10.00000 -0.54402 i
It was produced from the following source, using gnuplot:
set table "../plots/pgfmanual-sine.table"
set format "%.5f"
set samples 20
plot [x=0:10] sin(x)
The hlocal optionsi of the plot operation are local to each plot and do not affect other plots “on the same
path.” For example, plot[yshift=1cm] will locally shift the plot 1cm upward. Remember, however, that
327
most options can only be applied to paths as a whole. For example, plot[red] does not have the effect of
making the plot red. After all, you are trying to “locally” make part of the path red, which is not possible.
22.5
Plotting a Function
When you plot a function, the coordinates of the plot data can be computed by evaluating a mathematical
expression. Since pgf comes with a mathematical engine, you can specify this expression and then have
Tik Z produce the desired coordinates for you, automatically.
Since this case is quite common when plotting a function, the syntax is easy: Following the plot command
and its local options, you directly provide a hcoordinate expressioni. It looks like a normal coordinate, but
inside you may use a special macro, which is \x by default, but this can be changed using the variable
option. The hcoordinate expressioni is then evaluated for different values for \x and the resulting coordinates
are plotted.
Note that you will often have to put the x- or y-coordinate inside braces, namely whenever you use an
expression involving a parenthesis.
The following options influence how the hcoordinate expressioni is evaluated:
(no default, initially x)
/tikz/variable=hmacroi
Sets the macro whose value is set to the different values when hcoordinate expressioni is evaluated.
/tikz/samples=hnumber i
(no default, initially 25)
Sets the number of samples used in the plot.
/tikz/domain=hstarti:hend i
(no default, initially -5:5)
Sets the domain from which the samples are taken.
/tikz/samples at=hsample listi
(no default)
This option specifies a list of positions for which the variable should be evaluated. For instance, you
can say samples at={1,2,8,9,10} to have the variable evaluated exactly for values 1, 2, 8, 9, and 10.
You can use the \foreach syntax, so you can use ... inside the hsample listi.
When this option is used, the samples and domain option are overruled. The other way round, setting
either samples or domain will overrule this option.
f (x)
f (x) = x
f (x) =
1 x
20 e
x
f (x) = sin x
\begin{tikzpicture}[domain=0:4]
\draw[very thin,color=gray] (-0.1,-1.1) grid (3.9,3.9);
\draw[->] (-0.2,0) -- (4.2,0) node[right] {$x$};
\draw[->] (0,-1.2) -- (0,4.2) node[above] {$f(x)$};
\draw[color=red]
plot (\x,\x)
% \x r means to convert ’\x’ from degrees to
\draw[color=blue]
plot (\x,{sin(\x r)})
\draw[color=orange] plot (\x,{0.05*exp(\x)})
\end{tikzpicture}
node[right] {$f(x) =x$};
_r_adians:
node[right] {$f(x) = \sin x$};
node[right] {$f(x) = \frac{1}{20} \mathrm e^x$};
328
\tikz \draw[scale=0.5,domain=-3.141:3.141,smooth,variable=\t]
plot ({\t*sin(\t r)},{\t*cos(\t r)});
\tikz \draw[domain=0:360,smooth,variable=\t]
plot ({sin(\t)},\t/360,{cos(\t)});
22.6
Plotting a Function Using Gnuplot
Often, you will want to plot points that are given via a function like f (x) = x sin x. Unfortunately, TEX
does not really have enough computational power to generate the points of such a function efficiently (it is
a text processing program, after all). However, if you allow it, TEX can try to call external programs that
can easily produce the necessary points. Currently, Tik Z knows how to call gnuplot.
When Tik Z encounters your operation plot[id=hid i] function{x*sin(x)} for the first time, it will
create a file called hprefix ihid i.gnuplot, where hprefix i is \jobname. by default, that is, the name of your
main .tex file. If no hid i is given, it will be empty, which is alright, but it is better when each plot has
a unique hid i for reasons explained in a moment. Next, Tik Z writes some initialization code into this file
followed by plot x*sin(x). The initialization code sets up things such that the plot operation will write
the coordinates into another file called hprefix ihid i.table. Finally, this table file is read as if you had said
plot file{hprefix ihid i.table}.
For the plotting mechanism to work, two conditions must be met:
1. You must have allowed TEX to call external programs. This is often switched off by default since this
is a security risk (you might, without knowing, run a TEX file that calls all sorts of “bad” commands).
To enable this “calling external programs” a command line option must be given to the TEX program.
Usually, it is called something like shell-escape or enable-write18. For example, for my pdflatex
the option --shell-escape can be given.
2. You must have installed the gnuplot program and TEX must find it when compiling your file.
Unfortunately, these conditions will not always be met. Especially if you pass some source to a coauthor
and the coauthor does not have gnuplot installed, he or she will have trouble compiling your files.
For this reason, Tik Z behaves differently when you compile your graphic for the second time:
If upon reaching plot[id=hid i] function{...} the file hprefix ihid i.table already exists and if the
hprefix ihid i.gnuplot file contains what Tik Z thinks that it “should” contain, the .table file is immediately read without trying to call a gnuplot program. This approach has the following advantages:
1. If you pass a bundle of your .tex file and all .gnuplot and .table files to someone else, that person
can TEX the .tex file without having to have gnuplot installed.
2. If the \write18 feature is switched off for security reasons (a good idea), then, upon the first compilation of the .tex file, the .gnuplot will still be generated, but not the .table file. You can then
simply call gnuplot “by hand” for each .gnuplot file, which will produce all necessary .table files.
3. If you change the function that you wish to plot or its domain, Tik Z will automatically try to regenerate
the .table file.
4. If, out of laziness, you do not provide an id, the same .gnuplot will be used for different plots, but
this is not a problem since the .table will automatically be regenerated for each plot on-the-fly. Note:
If you intend to share your files with someone else, always use an id, so that the file can by typeset
without having gnuplot installed. Also, having unique ids for each plot will improve compilation
speed since no external programs need to be called, unless it is really necessary.
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When you use plot function{hgnuplot formulai}, the hgnuplot formulai must be given in the gnuplot
syntax, whose details are beyond the scope of this manual. Here is the ultra-condensed essence: Use x as
the variable and use the C-syntax for normal plots, use t as the variable for parametric plots. Here are some
examples:
f (x)
f (x) = x
f (x) =
1 x
20 e
x
f (x) = sin x
\begin{tikzpicture}[domain=0:4]
\draw[very thin,color=gray] (-0.1,-1.1) grid (3.9,3.9);
\draw[->] (-0.2,0) -- (4.2,0) node[right] {$x$};
\draw[->] (0,-1.2) -- (0,4.2) node[above] {$f(x)$};
\draw[color=red]
plot[id=x]
function{x}
node[right] {$f(x) =x$};
\draw[color=blue]
plot[id=sin] function{sin(x)}
node[right] {$f(x) = \sin x$};
\draw[color=orange] plot[id=exp] function{0.05*exp(x)} node[right] {$f(x) = \frac{1}{20} \mathrm e^x$};
\end{tikzpicture}
The plot is influenced by the following options: First, the options samples and domain explained earlier.
Second, there are some more specialized options.
(default true)
/tikz/parametric=hbooleani
Sets whether the plot is a parametric plot. If true, then t must be used instead of x as the parameter and
two comma-separated functions must be given in the hgnuplot formulai. An example is the following:
\tikz \draw[scale=0.5,domain=-3.141:3.141,smooth]
plot[parametric,id=parametric-example] function{t*sin(t),t*cos(t)};
/tikz/range=hstarti:hend i
(no default)
This key sets the range of the plot. If set, all points whose y-coordinates lie outside this range will be
considered to be outliers and will cause jumps in the plot, by default:
\tikz \draw[scale=0.5,domain=-3.141:3.141, samples=100, smooth, range=-3:3]
plot[id=tan-example] function{tan(x)};
/tikz/yrange=hstarti:hend i
(no default)
Same as range.
330
/tikz/xrange=hstarti:hend i
(no default)
Set the x-range. This makes sense only for parametric plots.
\tikz \draw[scale=0.5,domain=-3.141:3.141,smooth,xrange=0:1]
plot[parametric,id=parametric-example-cut] function{t*sin(t),t*cos(t)};
/tikz/id=hid i
(no default)
Sets the identifier of the current plot. This should be a unique identifier for each plot (though things will
also work if it is not, but not as well, see the explanations above). The hid i will be part of a filename,
so it should not contain anything fancy like * or $.
/tikz/prefix=hprefix i
(no default)
The hprefix i is put before each plot file name. The default is \jobname., but if you have many plots,
it might be better to use, say plots/ and have all plots placed in a directory. You have to create the
directory yourself.
(no value)
/tikz/raw gnuplot
This key causes the hgnuplot formulai to be passed on to gnuplot without setting up the samples or
the plot operation. Thus, you could write
plot[raw gnuplot,id=raw-example] function{set samples 25; plot sin(x)}
This can be useful for complicated things that need to be passed to gnuplot. However, for really complicated situations you should create a special external generating gnuplot file and use the file-syntax
to include the table “by hand.”
The following styles influence the plot:
(style, initially empty)
/tikz/every plot
This style is installed in each plot, that is, as if you always said
plot[every plot,...]
This is most useful for globally setting a prefix for all plots by saying:
\tikzset{every plot/.style={prefix=plots/}}
22.7
Placing Marks on the Plot
As we saw already, it is possible to add marks to a plot using the mark option. When this option is used, a
copy of the plot mark is placed on each point of the plot. Note that the marks are placed after the whole
path has been drawn/filled/shaded. In this respect, they are handled like text nodes.
In detail, the following options govern how marks are drawn:
/tikz/mark=hmark mnemonici
(no default)
Sets the mark to a mnemonic that has previously been defined using the \pgfdeclareplotmark. By
default, *, +, and x are available, which draw a filled circle, a plus, and a cross as marks. Many more
marks become available when the library plotmarks is loaded. Section 62.6 lists the available plot
marks.
One plot mark is special: the ball plot mark is available only in Tik Z. The ball color option determines the balls’s color. Do not use this option with a large number of marks since it will take very long
to render in PostScript.
Option
Effect
mark=ball
331
/tikz/mark repeat=hr i
(no default)
This option tells Tik Z that only every rth mark should be drawn.
\tikz \draw plot[mark=x,mark repeat=3,smooth] file {plots/pgfmanual-sine.table};
(no default)
/tikz/mark phase=hpi
This option tells Tik Z that the first mark to be draw should be the pth, followed by the (p + r)th, then
the (p + 2r)th, and so on.
\tikz \draw plot[mark=x,mark repeat=3,mark phase=6,smooth] file {plots/pgfmanual-sine.table};
(no default)
/tikz/mark indices=hlisti
This option allows you to specify explicitly the indices at which a mark should be placed. Counting
starts with 1. You can use the \foreach syntax, that is, ... can be used.
\tikz \draw plot[mark=x,mark indices={1,4,...,10,11,12,...,16,20},smooth]
file {plots/pgfmanual-sine.table};
(no default)
/tikz/mark size=hdimensioni
Sets the size of the plot marks. For circular plot marks, hdimensioni is the radius, for other plot marks
hdimensioni should be about half the width and height.
This option is not really necessary, since you achieve the same effect by specifying scale=hfactor i as
a local option, where hfactor i is the quotient of the desired size and the default size. However, using
mark size is a bit faster and more natural.
(style, no value)
/tikz/every mark
This style is installed before drawing plot marks. For example, you can scale (or otherwise transform)
the plot mark or set its color.
(no default)
/tikz/mark options=hoptionsi
Redefines every mark such that it sets {hoptionsi}.
\tikz \fill[fill=blue!20]
plot[mark=triangle*,mark options={color=blue,rotate=180}]
file{plots/pgfmanual-sine.table} |- (0,0);
332
(style, no value)
/tikz/no marks
Disables markers (the same as mark=none).
(style, no value)
/tikz/no markers
Disables markers (the same as mark=none).
22.8
Smooth Plots, Sharp Plots, Jump Plots, Comb Plots and Bar Plots
There are different things the plot operation can do with the points it reads from a file or from the inlined
list of points. By default, it will connect these points by straight lines. However, you can also use options
to change the behavior of plot.
(no value)
/tikz/sharp plot
This is the default and causes the points to be connected by straight lines. This option is included only
so that you can “switch back” if you “globally” install, say, smooth.
(no value)
/tikz/smooth
This option causes the points on the path to be connected using a smooth curve:
\tikz\draw plot[smooth] file{plots/pgfmanual-sine.table};
Note that the smoothing algorithm is not very intelligent. You will get the best results if the bending
angles are small, that is, less than about 30◦ and, even more importantly, if the distances between points
are about the same all over the plotting path.
(no default)
/tikz/tension=hvaluei
This option influences how “tight” the smoothing is. A lower value will result in sharper corners, a
higher value in more “round” curves. A value of 1 results in a circle if four points at quarter-positions
on a circle are given. The default is 0.55. The “correct” value depends on the details of plot.
\begin{tikzpicture}[smooth cycle]
\draw
plot[tension=0.2]
coordinates{(0,0) (1,1) (2,0) (1,-1)};
\draw[yshift=-2.25cm] plot[tension=0.5]
coordinates{(0,0) (1,1) (2,0) (1,-1)};
\draw[yshift=-4.5cm] plot[tension=1]
coordinates{(0,0) (1,1) (2,0) (1,-1)};
\end{tikzpicture}
(no value)
/tikz/smooth cycle
This option causes the points on the path to be connected using a closed smooth curve.
\tikz[scale=0.5]
\draw plot[smooth cycle] coordinates{(0,0) (1,0) (2,1) (1,2)}
plot
coordinates{(0,0) (1,0) (2,1) (1,2)} -- cycle;
333
(no value)
/tikz/const plot
This option causes the points on the path to be connected using piecewise constant series of lines:
\tikz\draw plot[const plot] file{plots/pgfmanual-sine.table};
(no value)
/tikz/const plot mark left
Just an alias for /tikz/const plot.
\tikz\draw plot[const plot mark left,mark=*] file{plots/pgfmanual-sine.table};
(no value)
/tikz/const plot mark right
A variant of /tikz/const plot which places its mark on the right ends:
\tikz\draw plot[const plot mark right,mark=*] file{plots/pgfmanual-sine.table};
(no value)
/tikz/const plot mark mid
A variant of /tikz/const plot which places its mark in the middle of the horizontal lines:
\tikz\draw plot[const plot mark mid,mark=*] file{plots/pgfmanual-sine.table};
More precisely, it generates vertical lines in the middle between each pair of consecutive points. If the
mesh width is constant, this leads to symmetrically placed marks (“middle”).
(no value)
/tikz/jump mark left
This option causes the points on the path to be drawn using piecewise constant, non-connected series
of lines. If there are any marks, they will be placed on left open ends:
\tikz\draw plot[jump mark left, mark=*] file{plots/pgfmanual-sine.table};
334
(no value)
/tikz/jump mark right
This option causes the points on the path to be drawn using piecewise constant, non-connected series
of lines. If there are any marks, they will be placed on right open ends:
\tikz\draw plot[jump mark right, mark=*] file{plots/pgfmanual-sine.table};
(no value)
/tikz/jump mark mid
This option causes the points on the path to be drawn using piecewise constant, non-connected series
of lines. If there are any marks, they will be placed in the middle of the horizontal line segments:
\tikz\draw plot[jump mark right, mark=*] file{plots/pgfmanual-sine.table};
In case of non–constant mesh widths, the same remarks as for const plot mark mid apply.
(no value)
/tikz/ycomb
This option causes the plot operation to interpret the plotting points differently. Instead of connecting
them, for each point of the plot a straight line is added to the path from the x-axis to the point, resulting
in a sort of “comb” or “bar diagram.”
\tikz\draw[ultra thick] plot[ycomb,thin,mark=*] file{plots/pgfmanual-sine.table};
\begin{tikzpicture}[ycomb]
\draw[color=red,line width=6pt]
plot coordinates{(0,1) (.5,1.2) (1,.6) (1.5,.7) (2,.9)};
\draw[color=red!50,line width=4pt,xshift=3pt]
plot coordinates{(0,1.2) (.5,1.3) (1,.5) (1.5,.2) (2,.5)};
\end{tikzpicture}
(no value)
/tikz/xcomb
This option works like ycomb except that the bars are horizontal.
\tikz \draw plot[xcomb,mark=x] coordinates{(1,0) (0.8,0.2) (0.6,0.4) (0.2,1)};
(no value)
/tikz/polar comb
This option causes a line from the origin to the point to be added to the path for each plot point.
335
\tikz \draw plot[polar comb,
mark=pentagon*,mark options={fill=white,draw=red},mark size=4pt]
coordinates {(0:1cm) (30:1.5cm) (160:.5cm) (250:2cm) (-60:.8cm)};
/tikz/ybar
(no value)
This option produces fillable bar plots. It is thus very similar to ycomb, but it employs rectangular
shapes instead of line-to operations. It thus allows to use any fill- or pattern style.
\tikz\draw[draw=blue,fill=blue!60!black] plot[ybar] file{plots/pgfmanual-sine.table};
\begin{tikzpicture}[ybar]
\draw[color=red,fill=red!80,bar width=6pt]
plot coordinates{(0,1) (.5,1.2) (1,.6) (1.5,.7) (2,.9)};
\draw[color=red!50,fill=red!20,bar width=4pt,bar shift=3pt]
plot coordinates{(0,1.2) (.5,1.3) (1,.5) (1.5,.2) (2,.5)};
\end{tikzpicture}
The use of bar width and bar shift is explained in the plot handler library documentation, section 62.4. Please refer to page 676.
(no value)
/tikz/xbar
This option works like ybar except that the bars are horizontal.
\tikz \draw[pattern=north west lines] plot[xbar]
coordinates{(1,0) (0.4,1) (1.7,2) (1.6,3)};
(no value)
/tikz/ybar interval
As /tikz/ybar, this options produces vertical bars. However, bars are centered at coordinate intervals
instead of interval edges, and the bar’s width is also determined relatively to the interval’s length:
\begin{tikzpicture}[ybar interval,x=10pt]
\draw[color=red,fill=red!80]
plot coordinates{(0,2) (2,1.2) (3,.3) (5,1.7) (8,.9) (9,.9)};
\end{tikzpicture}
Since there are N intervals [xi , xi+1 ] for given N + 1 coordinates, you will always have one coordinate
more than bars. The last y value will be ignored.
You can configure relative shifts and relative bar widths, which is explained in the plot handler library
documentation, section 62.4. Please refer to page 677.
336
(no value)
/tikz/xbar interval
Works like ybar interval, but for horizontal bar plots.
\begin{tikzpicture}[xbar interval,x=0.5cm,y=0.5cm]
\draw[color=red,fill=red!80]
plot coordinates {(3,0) (2,1) (4,1.5) (1,4) (2,6) (2,7)};
\end{tikzpicture}
(no value)
/tikz/only marks
This option causes only marks to be shown; no path segments are added to the actual path. This can
be useful for quickly adding some marks to a path.
\tikz \draw (0,0) sin (1,1) cos (2,0)
plot[only marks,mark=x] coordinates{(0,0) (1,1) (2,0) (3,-1)};
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23
Transparency
23.1
Overview
Normally, when you paint something using any of Tik Z’s commands (this includes stroking, filling, shading,
patterns, and images), the newly painted objects totally obscure whatever was painted earlier in the same
area.
You can change this behaviour by using something that can be thought of as “(semi)transparent colors.”
Such colors do not completely obscure the background, rather they blend the background with the new color.
At first sight, using such semitransparent colors might seem quite straightforward, but the math going on
in the background is quite involved and the correct handling of transparency fills some 64 pages in the PDF
specification.
In the present section, we start with the different ways of specifying “how transparent” newly drawn
objects should be. The simplest way is to just specify a percentage like “60% transparent.” A much more
general way is to use something that I call a fading, also known as a soft mask or a mask.
At the end of the section we address the problem of creating so-called transparency groups. This problem
arises when you paint over a position several times with a semitransparent color. Sometimes you want the
effect to accumulate, sometimes you do not.
Note: Transparency is best supported by the pdfTEX driver. The svg driver also has some support. For
PostScript output, opacity is rendered correctly only with the most recent versions of Ghostscript. Printers
and other programs will typically ignore the opacity setting.
23.2
Specifying a Uniform Opacity
Specifying a stroke and/or fill opacity is quite easy using the following options.
(no default)
/tikz/draw opacity=hvaluei
This option sets “how transparent” lines should be. A value of 1 means “fully opaque” or “not transparent
at all,” a value of 0 means “fully transparent” or “invisible.” A value of 0.5 yields lines that are
semitransparent.
Note that when you use PostScript as your output format, this option works only with recent versions
of Ghostscript.
\begin{tikzpicture}[line width=1ex]
\draw (0,0) -- (3,1);
\filldraw [fill=yellow!80!black,draw opacity=0.5] (1,0) rectangle (2,1);
\end{tikzpicture}
Note that the draw opacity options only sets the opacity of drawn lines. The opacity of fillings is set
using the option fill opacity (documented in Section 15.5.3. The option opacity sets both at the same
time.
(no default)
/tikz/opacity=hvaluei
Sets both the drawing and filling opacity to hvaluei.
The following predefined styles make it easier to use this option:
/tikz/transparent
Makes everything totally transparent and, hence, invisible.
(style, no value)
\tikz{\fill[red]
(0,0)
rectangle (1,0.5);
\fill[transparent,red] (0.5,0) rectangle (1.5,0.25); }
(style, no value)
/tikz/ultra nearly transparent
Makes everything, well, ultra nearly transparent.
\tikz{\fill[red]
(0,0)
rectangle (1,0.5);
\fill[ultra nearly transparent] (0.5,0) rectangle (1.5,0.25); }
338
(style, no value)
/tikz/very nearly transparent
\tikz{\fill[red]
(0,0)
rectangle (1,0.5);
\fill[very nearly transparent] (0.5,0) rectangle (1.5,0.25); }
(style, no value)
/tikz/nearly transparent
\tikz{\fill[red]
(0,0)
rectangle (1,0.5);
\fill[nearly transparent] (0.5,0) rectangle (1.5,0.25); }
(style, no value)
/tikz/semitransparent
\tikz{\fill[red]
(0,0)
rectangle (1,0.5);
\fill[semitransparent] (0.5,0) rectangle (1.5,0.25); }
(style, no value)
/tikz/nearly opaque
\tikz{\fill[red]
(0,0)
rectangle (1,0.5);
\fill[nearly opaque] (0.5,0) rectangle (1.5,0.25); }
(style, no value)
/tikz/very nearly opaque
\tikz{\fill[red]
(0,0)
rectangle (1,0.5);
\fill[very nearly opaque] (0.5,0) rectangle (1.5,0.25); }
(style, no value)
/tikz/ultra nearly opaque
\tikz{\fill[red]
(0,0)
rectangle (1,0.5);
\fill[ultra nearly opaque] (0.5,0) rectangle (1.5,0.25); }
/tikz/opaque
This yields completely opaque drawings, which is the default.
(style, no value)
\tikz{\fill[red]
(0,0)
rectangle (1,0.5);
\fill[opaque] (0.5,0) rectangle (1.5,0.25); }
(no default)
/tikz/fill opacity=hvaluei
This option sets the opacity of fillings. In addition to filling operations, this opacity also applies to text
and images.
Note, again, that when you use PostScript as your output format, this option works only with recent
versions of Ghostscript.
\begin{tikzpicture}[thick,fill opacity=0.5]
\filldraw[fill=red]
(0:1cm)
circle (12mm);
\filldraw[fill=green] (120:1cm) circle (12mm);
\filldraw[fill=blue] (-120:1cm) circle (12mm);
\end{tikzpicture}
B
\begin{tikzpicture}
\fill[red] (0,0) rectangle (3,2);
\node
at (0,0) {\huge A};
\node[fill opacity=0.5] at (3,2) {\huge B};
\end{tikzpicture}
A
339
(no default)
/tikz/text opacity=hvaluei
Sets the opacity of text labels, overriding the fill opacity setting.
Upper node
Lower node
\begin{tikzpicture}[every node/.style={fill,draw}]
\draw[line width=2mm,blue!50,line cap=round] (0,0) grid (3,2);
\node[opacity=0.5] at (1.5,2) {Upper node};
\node[draw opacity=0.8,fill opacity=0.2,text opacity=1]
at (1.5,0) {Lower node};
\end{tikzpicture}
Note the following effect: If you set up a certain opacity for stroking or filling and you stroke or fill the
same area twice, the effect accumulates:
\begin{tikzpicture}[fill opacity=0.5]
\fill[red] (0,0) circle (1);
\fill[red] (1,0) circle (1);
\end{tikzpicture}
Often, this is exactly what you intend, but not always. You can use transparency groups, see the end of
this section, to change this.
23.3
Blend Modes
A blend mode specifies how colors mix when you paint on a canvas. Normally, if you paint a red box on a
green circle, the red color will completely replace the green circle. However, in some situations you might
also wish the red color to somehow “mix” or “blend” with the green circle. We already saw that, using
transparency, we can draw something without completely obscuring the background. Blending is a similar
operation, only here we mix colors in more complicated ways.
Note: Blending is a rather “advanced” feature of pdf. Most renderers, let alone printers, will have trouble
rendering blending correctly.
(no default)
/tikz/blend mode=hmodei
Sets the current blend mode to hmodei. Here hmodei must be one of the modes listed below. More
details on these modes can also be found in Section 7.2.4 of the pdf Specification, version 1.7.
In the following example, the blend mode is only used and set inside a transparency group (see also
Section 23.5). This is because most renderers (viewing programs) have trouble rendering blending
correctly otherwise. For instance, at the time of writing, the versions of Adobe’s Reader and Apple’s
Preview render the following drawing very differently, if the transparency group is not used in the
following example.
\tikz {
\begin{scope}[transparency group]
\begin{scope}[blend mode=screen]
\fill[red!90!black]
( 90:.6) circle (1);
\fill[green!80!black] (210:.6) circle (1);
\fill[blue!90!black] (330:.6) circle (1);
\end{scope}
\end{scope}
}
Because of the trouble with rendering blending correctly outside transparency groups, there is a special
key that establishes a transparency group and sets a blend mode simultaneously:
(no default)
/tikz/blend group=hmodei
This key can only be used with a scope (like transparency group). It will cause the current scope
to become a transparency group and, inside this group, the blend mode will be set to hmodei.
340
\tikz [blend group=screen] {
\fill[red!90!black]
( 90:.6) circle (1);
\fill[green!80!black] (210:.6) circle (1);
\fill[blue!90!black] (330:.6) circle (1);
}
Here is an overview of the effects of the different available blend modes. In the examples, we always
have three circles drawn on top of each other (as in the example code earlier): We start with a triple
of pure red, green, and blue. Below it, we have a triple of light versions of these three colors (red!50,
green!50, and blue!50). Next comes the triple yellow, cyan, and magenta; again with a triple of light
versions below it. The large example consists of three balls (produced using ball color) having the
colors red, green, and blue, are drawn on top of each other just like the circles.
Example
Mode
Explanations quoted from Table 7.2 of the pdf
Specification, Version 1.7
normal
When painting a pixel with a some color (called the
“source color”), the background color (called the
“backdrop”) is completely ignored.
multiply
Multiplies the backdrop and source color values. The
result color is always at least as dark as either of the two
constituent colors. Multiplying any color with black
produces black; multiplying with white leaves the original
color unchanged. Painting successive overlapping objects
with a color other than black or white produces
progressively darker colors.
screen
Multiplies the complements of the backdrop and source
color values, then complements the result. The result color
is always at least as light as either of the two constituent
colors. Screening any color with white produces white;
screening with black leaves the original color unchanged.
The effect is similar to projecting multiple photographic
slides simultaneously onto a single screen.
overlay
Multiplies or screens the colors, depending on the
backdrop color value. Source colors overlay the backdrop
while preserving its highlights and shadows. The backdrop
color is not replaced but is mixed with the source color to
reflect the lightness or darkness of the backdrop.
darken
Selects the darker of the backdrop and source colors. The
backdrop is replaced with the source where the source is
darker; otherwise, it is left unchanged.
lighten
Selects the lighter of the backdrop and source colors. The
backdrop is replaced with the source where the source is
lighter; otherwise, it is left unchanged.
colordodge Brightens the backdrop color to reflect the source color.
Painting with black produces no changes.
341
colorburn
Darkens the backdrop color to reflect the source color.
Painting with white produces no change.
hardlight
Multiplies or screens the colors, depending on the source
color value. The effect is similar to shining a harsh
spotlight on the backdrop.
softlight
Darkens or lightens the colors, depending on the source
color value. The effect is similar to shining a diffused
spotlight on the backdrop.
difference Subtracts the darker of the two constituent colors from
the lighter color. Painting with white inverts the backdrop
color; painting with black produces no change.
exclusion
Produces an effect similar to that of the Difference mode
but lower in contrast. Painting with white inverts the
backdrop color; painting with black produces no change.
hue
Creates a color with the hue of the source color and the
saturation and luminosity of the backdrop color.
saturation Creates a color with the saturation of the source color and
the hue and luminosity of the backdrop color. Painting
with this mode in an area of the backdrop that is a pure
gray (no saturation) produces no change.
color
Creates a color with the hue and saturation of the source
color and the luminosity of the backdrop color. This
preserves the gray levels of the backdrop and is useful for
coloring monochrome images or tinting color images.
luminosity Creates a color with the luminosity of the source color and
the hue and saturation of the backdrop color. This
produces an inverse effect to that of the Color mode.
23.4
Fadings
For complicated graphics, uniform transparency settings are not always sufficient. Suppose, for instance,
that while you paint a picture, you want the transparency to vary smoothly from completely opaque to
completely transparent. This is a “shading-like” transparency. For such a form of transparency I will use the
term fading (as a noun). They are also known as soft masks, opacity masks, masks, or soft clips.
23.4.1
Creating Fadings
How do we specify a fading? This is a bit of an art since the underlying mechanism is quite powerful, but a
bit difficult to use.
Let us start with a bit of terminology. A fading specifies for each point of an area the transparency of
that point. This transparency can by any number between 0 and 1. A fading picture is a normal graphic
that, in a way to be described in a moment, determines the transparency of points inside the fading. Each
fading has an underlying fading picture.
342
The fading picture is a normal graphic drawn using any of the normal graphic drawing commands. A
fading and its fading picture are related as follows: Given any point of the fading, the transparency of this
point is determined by the luminosity of the fading picture at the same position. The luminosity of a point
determines “how bright” the point is. The brighter the point in the fading picture, the more opaque is the
point in the fading. In particular, a white point of the fading picture is completely opaque in the fading and
a black point of the fading picture is completely transparent in the fading. (The background of the fading
picture is always transparent in the fading as if the background were black.)
It is rather counter-intuitive that a white pixel of the fading picture will be opaque in the fading and a
black pixel will be transparent. For this reason, Tik Z defines a color called transparent that is the same as
black. The nice thing about this definition is that the color transparent!hpercentagei in the fading picture
yields a pixel that is hpercentagei percent transparent in the fading.
Turning a fading picture into a normal picture is achieved using the following commands, which
are only defined in the library, namely the library fadings. So, to use them, you have to say
\usetikzlibrary{fadings} first.
\begin{tikzfadingfrompicture}[hoptionsi]
henvironment contentsi
\end{tikzfadingfrompicture}
This command works like a {tikzpicture}, only the picture is not shown, but instead a fading is
defined based on this picture. To set the name of the picture, use the name option (which is normally
used to set the name of a node).
(no default)
/tikz/name={hnamei}
Use this option with the {tikzfadingfrompicture} environment to set the name of the fading.
You must provide this option.
The following shading is 2cm by 2cm and gets more and more transparent from left to right, but is 50%
transparent for a large circle in the middle.
\begin{tikzfadingfrompicture}[name=fade right]
\shade[left color=transparent!0,
right color=transparent!100] (0,0) rectangle (2,2);
\fill[transparent!50] (1,1) circle (0.7);
\end{tikzfadingfrompicture}
% Now we use the fading in another picture:
\begin{tikzpicture}
% Background
\fill [black!20] (-1.2,-1.2) rectangle (1.2,1.2);
\pattern [pattern=checkerboard,pattern color=black!30]
(-1.2,-1.2) rectangle (1.2,1.2);
\fill [path fading=fade right,red] (-1,-1) rectangle (1,1);
\end{tikzpicture}
In the next example we create a fading picture that contains some text. When the fading is used, we
only see the shading “through it.”
TikZ
\begin{tikzfadingfrompicture}[name=tikz]
\node [text=transparent!20]
{\fontfamily{ptm}\fontsize{45}{45}\bfseries\selectfont Ti\emph{k}Z};
\end{tikzfadingfrompicture}
% Now we use the fading in another picture:
\begin{tikzpicture}
\fill [black!20] (-2,-1) rectangle (2,1);
\pattern [pattern=checkerboard,pattern color=black!30]
(-2,-1) rectangle (2,1);
\shade[path fading=tikz,fit fading=false,
left color=blue,right color=black]
(-2,-1) rectangle (2,1);
\end{tikzpicture}
The same effect can also be achieved using knockout groups, see Section 23.5.
\tikzfadingfrompicture[hoptionsi]
343
henvironment contentsi
\endtikzfadingfrompicture
The plainTEX version of the environment.
\starttikzfadingfrompicture[hoptionsi]
henvironment contentsi
\stoptikzfadingfrompicture
The ConTEXt version of the environment.
\tikzfading[hoptionsi]
This command is used to define a fading similarly to the way a shading is defined. In the hoptionsi you
should
1. use the name=hnamei option to set a name for the fading,
2. use the shading option to set the name of the shading that you wish to use,
3. extra options for setting the colors of the shading (typically you will set them to the color transparent!hpercentagei).
Then, a new fading named hnamei will be created based on the shading.
\tikzfading[name=fade right,
left color=transparent!0,
right color=transparent!100]
% Now we use the fading in another picture:
\begin{tikzpicture}
% Background
\fill [black!20] (-1.2,-1.2) rectangle (1.2,1.2);
\path [pattern=checkerboard,pattern color=black!30]
(-1.2,-1.2) rectangle (1.2,1.2);
\fill [red,path fading=fade right] (-1,-1) rectangle (1,1);
\end{tikzpicture}
\tikzfading[name=fade out,
inner color=transparent!0,
outer color=transparent!100]
% Now we use the fading in another picture:
\begin{tikzpicture}
% Background
\fill [black!20] (-1.2,-1.2) rectangle (1.2,1.2);
\path [pattern=checkerboard,pattern color=black!30]
(-1.2,-1.2) rectangle (1.2,1.2);
\fill [blue,path fading=fade out] (-1,-1) rectangle (1,1);
\end{tikzpicture}
23.4.2
Fading a Path
A fading specifies for each pixel of a certain area how transparent this pixel will be. The following options
are used to install such a fading for the current scope or path.
(default scope’s setting)
/tikz/path fading=hnamei
This option tells Tik Z that the current path should be faded with the fading hnamei. If no hnamei is
given, the hnamei set for the whole scope is used. Similarly to options like draw or fill, this option
is reset for each path, so you have to add it to each path that should be faded. You can also specify
none as hnamei, in which case fading for the path will be switched off in case it has been switched on
by previous options or styles.
344
\begin{tikzpicture}[path fading=south]
% Checker board
\fill [black!20] (0,0) rectangle (4,3);
\pattern [pattern=checkerboard,pattern color=black!30]
(0,0) rectangle (4,3);
\fill [color=blue]
(0.5,1.5) rectangle +(1,1);
\fill [color=blue,path fading=north] (2.5,1.5) rectangle +(1,1);
\fill [color=red,path fading]
\fill [color=red]
\end{tikzpicture}
(1,0.75) ellipse (.75 and .5);
(3,0.75) ellipse (.75 and .5);
(default true, initially true)
/tikz/fit fading=hbooleani
When set to true, the fading is shifted and resized (in exactly the same way as a shading) so that
it covers the current path. When set to false, the fading is only shifted so that it is centered on
the path’s center, but it is not resized. This can be useful for special-purpose fadings, for instance
when you use a fading to “punch out” something.
/tikz/fading transform=htransformation optionsi
(no default)
The htransformation optionsi are applied to the fading before it is used. For instance, if
htransformation optionsi is set to rotate=90, the fading is rotated by 90 degrees.
\begin{tikzpicture}[path fading=fade down]
% Checker board
\fill [black!20] (0,0) rectangle (4,1.5);
\path [pattern=checkerboard,pattern color=black!30] (0,0) rectangle (4,1.5);
\fill [red,path fading,fading transform={rotate=90}]
(1,0.75) ellipse (.75 and .5);
\fill [red,path fading,fading transform={rotate=30}]
(3,0.75) ellipse (.75 and .5);
\end{tikzpicture}
(no default)
/tikz/fading angle=hdegreei
A shortcut for fading transform={rotate=hdegreei}.
Note that you can “fade just about anything.” In particular, you can fade a shading.
\begin{tikzpicture}
% Checker board
\fill [black!20] (0,0) rectangle (4,4);
\path [pattern=checkerboard,pattern color=black!30] (0,0) rectangle (4,4);
\shade [ball color=blue,path fading=south] (2,2) circle (1.8);
\end{tikzpicture}
The fade inside of the following example is more transparent in the middle than on the outside.
\tikzfading[name=fade inside,
inner color=transparent!80,
outer color=transparent!30]
\begin{tikzpicture}
% Checker board
\fill [black!20] (0,0) rectangle (4,4);
\path [pattern=checkerboard,pattern color=black!30] (0,0) rectangle (4,4);
\shade [ball color=red] (3,3) circle (0.8);
\shade [ball color=white,path fading=fade inside] (2,2) circle (1.8);
\end{tikzpicture}
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Note that adding the path fading option to a node fades the (background) path, not the text itself.
To fade the text, you need to use a scope fading (see below).
Note that using fadings in conjunction with patterns can create visually rather pleasing effects:
\tikzfading[name=middle,
top color=transparent!50,
bottom color=transparent!50,
middle color=transparent!20]
\begin{tikzpicture}
\node
[circle,circular drop shadow,
pattern=horizontal lines dark blue,
path fading=south,
minimum size=3.6cm] {};
\pattern
[path fading=north,
pattern=horizontal lines dark gray]
(0,0) circle (1.8cm);
\pattern
[path fading=middle,
pattern=crosshatch dots light steel blue]
(0,0) circle (1.8cm);
\end{tikzpicture}
23.4.3
Fading a Scope
In addition to fading individual paths, you may also wish to “fade a scope,” that is, you may wish to install
a fading that is used globally to specify the transparency for all objects drawn inside a scope. This effect
can also be thought of as a “soft clip” and it works in a similar way: You add the scope fading option to a
path in a scope – typically the first one – and then all subsequent drawings in the scope are faded. You will
use a transparency group in conjunction, see the end of this section.
(no default)
/tikz/scope fading=hfadingi
In principle, this key works in exactly the same way as the path fading key. The only difference is, that
the effect of the fading will persist after the current path till the end of the scope. Thus, the hfadingi
is applied to all subsequent drawings in the current scope, not just to the current path. In this regard,
the option works very much like the clip option. (Note, however, that, unlike the clip option, fadings
to not accumulate unless a transparency group is used.)
The keys fit fading and fading transform have the same effect as for path fading. Also that,
just as for path fading, providing the scope fading option with a {scope} only sets the name of the
fading to be used. You have to explicitly provide the scope fading with a path to actually install a
fading.
\begin{tikzpicture}
\fill [black!20] (-2,-2) rectangle (2,2);
\pattern [pattern=checkerboard,pattern color=black!30]
(-2,-2) rectangle (2,2);
% The bounding box of the shading:
\draw [red] (-50bp,-50bp) rectangle (50bp,50bp);
\path [scope fading=south,fit fading=false] (0,0);
% fading is centered at its natural size
\fill[red]
( 90:1) circle (1);
\fill[green] (210:1) circle (1);
\fill[blue] (330:1) circle (1);
\end{tikzpicture}
In the following example we resize the fading to the size of the whole picture:
346
\begin{tikzpicture}
\fill [black!20] (-2,-2) rectangle (2,2);
\pattern [pattern=checkerboard,pattern color=black!30]
(-2,-2) rectangle (2,2);
\path [scope fading=south] (-2,-2) rectangle (2,2);
\fill[red]
( 90:1) circle (1);
\fill[green] (210:1) circle (1);
\fill[blue] (330:1) circle (1);
\end{tikzpicture}
Scope fadings are also needed if you wish to fade a node.
This is some text that
will fade out as we go
right and down. It is
pretty hard to achieve
this effect in other
ways.
23.5
\tikz \node [scope fading=south,fading angle=45,text width=3.5cm]
{
This is some text that will fade out as we go right
and down. It is pretty hard to achieve this effect in
other ways.
};
Transparency Groups
Consider the following cross and sign. They “look wrong” because we can see how they were constructed,
while this is not really part of the desired effect.
\begin{tikzpicture}[opacity=.5]
\draw [line width=5mm] (0,0) -- (2,2);
\draw [line width=5mm] (2,0) -- (0,2);
\end{tikzpicture}
\begin{tikzpicture}
\node at (0,0) [forbidden sign,line width=2ex,draw=red,fill=white] {Smoking};
Smoking
Smoking
\node [opacity=.5]
at (2,0) [forbidden sign,line width=2ex,draw=red,fill=white] {Smoking};
\end{tikzpicture}
Transparency groups are used to render them correctly:
\begin{tikzpicture}[opacity=.5]
\begin{scope}[transparency group]
\draw [line width=5mm] (0,0) -- (2,2);
\draw [line width=5mm] (2,0) -- (0,2);
\end{scope}
\end{tikzpicture}
\begin{tikzpicture}
\node at (0,0) [forbidden sign,line width=2ex,draw=red,fill=white] {Smoking};
Smoking
Smoking
\begin{scope}[opacity=.5,transparency group]
\node at (2,0) [forbidden sign,line width=2ex,draw=red,fill=white]
{Smoking};
\end{scope}
\end{tikzpicture}
(no default)
/tikz/transparency group=[hoptionsi]
This option can be given to a scope. It will have the following effect: The scope’s contents is stroked /
filled “ignoring any outside transparency.” This means, all previous transparency settings are ignored
347
(you can still set transparency inside the group, but never mind). For instance, in the forbidden sign
example, the whole sign is first painted (conceptually) like the image on the left hand side. Note that
some pixels of the sign are painted multiple times (up to three times), but only the last color “wins.”
Then, when the scope is finished, it is painted as a whole. The fill transparency settings are now applied
to the resulting picture. For instance, the pixel that has been painted three times is just red at the end,
so this red color will be blended with whatever is “behind” the group on the page.
Smoking
Smoking
\begin{tikzpicture}
\pattern[pattern=checkerboard,pattern color=black!15](-1,-1) rectangle (3,1);
\node at (0,0) [forbidden sign,line width=2ex,draw=red,fill=white] {Smoking};
\begin{scope}[transparency group,opacity=.5]
\node at (2,0) [forbidden sign,line width=2ex,draw=red,fill=white]
{Smoking};
\end{scope}
\end{tikzpicture}
Note that in the example, the opacity=.5 is not active inside the transparency group: The group is
only established at beginning of the scope and all options given to the {scope} environment are set
before the group is established. To change the opacity inside the group, you need to open another scope
inside it or use the opacity key with a command inside the group:
Smoking
Smoking
\begin{tikzpicture}
\pattern[pattern=checkerboard,pattern color=black!15](-1,-1) rectangle (3,1);
\node at (0,0) [forbidden sign,line width=2ex,draw=red,fill=white] {Smoking};
\begin{scope}[transparency group,opacity=.5]
\node (s) at (2,0) [forbidden sign,line width=2ex,draw=red,fill=white]
{Smoking};
\draw [opacity=.5, line width=2ex, blue] (1.2,0) -- (2.8,0);
\end{scope}
\end{tikzpicture}
The hoptionsi are a list of comma-separated options:
• knockout When this option is given inside the hoptionsi, the group becomes a so-called knockout
group. This means, essentially, that inside the group everything is painted as if the “opacity” of a
line or area were just another color channel. In particular, if you paint a pixel with opacity 0 inside
a knockout group, this pixel becomes perfectly transparent immediately. In contrast, painting a
pixel with something of opacity 0 normally has no effect.
Not all renderers, let alone printers, will support this. At the time of writing, Apple’s Preview will
not show the following correctly (you should see the text Tik Z in the middle):
TikZ
\begin{tikzpicture}
\shade [left color=red,right color=blue] (-2,-1) rectangle (2,1);
\begin{scope}[transparency group=knockout]
\fill [white] (-1.9,-.9) rectangle (1.9,.9);
\node [opacity=0,font=\fontfamily{ptm}\fontsize{45}{45}\bfseries]
{Ti\emph{k}Z};
\end{scope}
\end{tikzpicture}
In the example, we first draw a large shading and then, inside the transparency group “overwrite”
most of this shading by a big white rectangle. The interesting part is the text of the node, which
has opacity 0. Normally, this would mean that nothing is shown. However, in a knockout group,
we “paint” the text with an “opacity zero” color. The effect is that part of the totally opaque white
rectangle gets overwritten by a perfectly transparent area (namely exactly the area taken up by
the pixels of the text). When this whole knockout group is then placed on top of the shading, the
shading will “shine through” at the knocked-out pixels.
• isolated=false A group can be isolated or not. By default, they are isolated, since this is
typically what you want. For details on what isolated groups are, exactly, see Section 7.3.4 of the
pdf Specification, version 1.7.
Note that when a transparency group is created, Tik Z must correctly determine the size of the
material inside the group. Usually, this is no problem, but when you use things like overlay or
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transform canvas, trouble may result. In this case, please consult Section 110 on how to sidestep
this problem in such cases.
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24
24.1
Decorated Paths
Overview
Decorations are a general concept to make (sub)paths “more interesting.” Before we have a look at the
details, let us have a look at some examples:
\begin{tikzpicture}[thick]
\draw
\draw[decorate,decoration=zigzag]
\draw[decorate,decoration=brace]
\draw[decorate,decoration=triangles]
\draw[decorate,decoration={coil,segment length=4pt}]
\draw[decorate,decoration={coil,aspect=0}]
\draw[decorate,decoration={expanding waves,angle=7}]
\end{tikzpicture}
Bumpy
(0,3)
(0,2.5)
(0,2)
(0,1.5)
(0,1)
(0,.5)
(0,0)
--------
(3,3);
(3,2.5);
(3,2);
(3,1.5);
(3,1);
(3,.5);
(3,0);
\begin{tikzpicture}
\node [fill=red!20,draw,decorate,decoration={bumps,mirror},
minimum height=1cm]
{Bumpy};
\end{tikzpicture}
\begin{tikzpicture}
\filldraw[fill=blue!20]
(0,3)
decorate [decoration=saw]
{ -- (3,3) }
decorate [decoration={coil,aspect=0}] { -- (2,1) }
decorate [decoration=bumps]
{ -| (0,3) };
\end{tikzpicture}
Saved from trash
\begin{tikzpicture}
\node [fill=yellow!50,draw,thick, minimum height=2cm, minimum width=3cm,
decorate, decoration={random steps,segment length=3pt,amplitude=1pt}]
{Saved from trash};
\end{tikzpicture}
The general idea of decorations is the following: First, you construct a path using the usual path construction commands. The resulting path is, in essence, a series of straight and curved lines. Instead of directly
using this path for filling or drawing, you can then specify that it should form the basis for a decoration. In
this case, depending on which decoration you use, a new path is constructed “along” the path you specified.
For instance, with the zigzag decoration, the new path is a zigzagging line that goes along the old path.
Let us have a look at an example: In the first picture, we see a path that consists of a line, an arc, and
a line. In the second picture, this path has been used as the basis of a decoration.
\tikz \fill
[fill=blue!20,draw=blue,thick] (0,0) -- (2,1) arc (90:-90:.5) -- cycle;
\tikz \fill [decorate,decoration={zigzag}]
[fill=blue!20,draw=blue,thick] (0,0) -- (2,1) arc (90:-90:.5) -- cycle;
It is also possible to decorate only a subpath (the exact syntax will be explained later in this section).
\tikz \fill [decoration={zigzag}]
[fill=blue!20,draw=blue,thick] (0,0) -- (2,1)
decorate { arc (90:-90:.5) } -- cycle;
The zigzag decoration will be called a path morphing decoration because it morphs a path into a different,
but topologically equivalent path. Not all decorations are path morphing; rather there are three kinds of
decorations.
350
1. The just-mentioned path morphing decorations morph the path in the sense that what used to be a
straight line might afterwards be a squiggly line or might have bumps. However, a line is still and a
line and path deforming decorations do not change the number of subpaths.
Examples of such decorations are the snake or the zigzag decoration. Many such decorations are
defined in the library decorations.pathmorphing.
2. Path replacing decorations completely replace the path by a different path that is only “loosely based”
on the original path. For instance, the crosses decoration replaces a path by a path consisting of a
sequence of crosses. Note how in the following example filling the path has no effect since the path
consist only of (numerous) unconnected straight line subpaths:
\tikz \fill [decorate,decoration={crosses}]
[fill=blue!20,draw=blue,thick] (0,0) -- (2,1) arc (90:-90:.5) -- cycle;
Examples of path replacing decorations are crosses or ticks or shape backgrounds. Such decorations
are defined in the library decorations.pathreplacing, but also in decorations.shapes.
3. Path removing decorations completely remove the to-be-decorated path. Thus, they have no effect
on the main path that is being constructed. Instead, they typically have numerous side effects. For
instance, they might “write some text” along the (removed) path or they might place nodes along this
path. Note that for such decorations the path usage command for the main path have no influence on
how the decoration looks like.
is
ex t
alo
ng a
Th
t
is a
\tikz \fill [decorate,decoration={text along path,
text=This is a text along a path. Note how the path is lost.}]
[fill=blue!20,draw=blue,thick] (0,0) -- (2,1) arc (90:-90:.5) -- cycle;
path. Note how
Decorations are defined in different decoration libraries, see Section 48 for details. It is also possible to
define your own decorations, see Section 98, but you need to use the pgf basic layer and a bit of theory is
involved.
Decorations can be used to decorate already decorated paths. In the following three graphics, we start
with a simple path, then decorate it once, and then decorate the decorated path once more.
\tikz \fill [fill=blue!20,draw=blue,thick]
(0,0) rectangle (3,2);
\tikz \fill [fill=blue!20,draw=blue,thick]
decorate[decoration={zigzag,segment length=10mm,amplitude=2.5mm}]
{ (0,0) rectangle (3,2) };
\tikz \fill [fill=blue!20,draw=blue,thick]
decorate[decoration={crosses,segment length=2mm}] {
decorate[decoration={zigzag,segment length=10mm,amplitude=2.5mm}] {
(0,0) rectangle (3,2)
}
};
One final word of warning: Decorations can be pretty slow to typeset and they can be inaccurate. The
reason is that pgf has to a lot of rather difficult computations in the background and TEX is not very
good at doing math. Decorations are fastest when applied to straight line segments, but even then they are
351
much slower than other alternatives. For instance, the ticks decoration can be simulated by clever use of a
dashing pattern and the dashing pattern will literally be thousands of times faster to typeset. However, for
most decorations there are no real alternatives.
Tik Z Library decorations
\usetikzlibrary{decorations} % LATEX and plain TEX
\usetikzlibrary[decorations] % ConTEXt
In order to use decorations, you first have to load a decoration library. This decoration library defines
the basic options described in the following, but it does not define any new decorations. This is done by
libraries like decorations.text. Since these more specialized libraries include the decoration library
automatically, you usually do not have to bother about it.
24.2
Decorating a Subpath Using the Decorate Path Command
The most general way to decorate a (sub)path is the following path command.
\path . . . decorate[hoptionsi]{hsubpathi} . . . ;
This path operation causes the hsubpathi to be decorated using the current decoration. Depending on
the decoration, this may or may not extend the current path.
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\draw decorate [decoration={name=zigzag}]
{ (0,0) .. controls (0,2) and (3,0) .. (3,2) |- (0,0) };
\end{tikzpicture}
The path can include straight lines, curves, rectangles, arcs, circles, ellipses, and even already decorated
paths (that is, you can nest applications of the decorate path command, see below).
Due to the limits on the precision in TEX, some inaccuracies in positioning when crossing input segment
boundaries may occasionally be found.
You can use nodes normally inside the hsubpathi.
Hi!
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\draw decorate [decoration={name=zigzag}]
{ (0,0) -- (2,2) node (hi) [left,draw=red] {Hi!} arc(90:0:1)};
\draw [blue] decorate [decoration={crosses}] {(3,0) -- (hi)};
\end{tikzpicture}
The following key is used to select the decoration and also to select further “rendering options” for the
decoration.
/pgf/decoration=hdecoration optionsi
(no default)
alias /tikz/decoration
This option is used to specify which decoration is used and how it will look like. Note that this key
will not cause any decorations to be applied, immediately. It takes the decorate path command
or the decorate option to actually decorate a path. The decoration option is only used to specify
which decoration should be used, in principle. You can also use this option at the beginning of a
picture or a scope to specify the decoration to be used with each invocation of the decorate path
command. Naturally, any local options of the decorate path command override these “global”
options.
\begin{tikzpicture}[decoration=zigzag]
\draw
decorate
{(0,0) -- (3,2)};
\draw [red] decorate [decoration=crosses] {(0,2) -- (3,0)};
\end{tikzpicture}
352
The hdecoration optionsi are special options (which have the path prefix /pgf/decoration/) that
determine the properties of the decoration. Which options are appropriate for a decoration strongly
depend on the decoration, you will have to look up the appropriate options in the documentation
of the decoration, see Section 48.
There is one option (available only in Tik Z) that is special:
(no default, initially none)
/pgf/decoration/name=hnamei
Use this key to set which decoration is to be used. The hnamei can both be a decoration or a
meta-decoration (you need to worry about the difference only if you wish to define your own
decorations).
If you set hnamei to none, no decorations are added.
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\draw decorate [decoration={name=zigzag}]
{ (0,0) .. controls (0,2) and (3,0) .. (3,2) };
\end{tikzpicture}
Since this option is used so often, you can also leave out the name= part. Thus, the above
example can be rewritten more succinctly:
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\draw decorate [decoration=zigzag]
{ (0,0) .. controls (0,2) and (3,0) .. (3,2) };
\end{tikzpicture}
In general, when hdecoration optionsi are parsed, for each unknown key it is checked whether
that key happens to be a (meta-)decoration and, if so, the name option is executed for this key.
Further options allow you to adjust the position of decorations relative to the to-be-decorated path.
See Section 24.4 below for details.
Recall that some decorations actually completely remove the to-be-decorated path. In such cases, the
construction of the main path is resumed after the decorate path command ends.
around
\begin{tikzpicture}[decoration={text along path,text=
around and around and around and around we go}]
\draw (0,0) -- (1,1) decorate { -- (2,1) } -- (3,0);
\end{tikzpicture}
It is permissible to nest decorate commands. In this case, the path resulting from the first decoration
process is used as the to-be-decorated path for the second decoration process. This is especially useful
for drawing fractals. The Koch snowflake decoration replaces a straight line like
by
.
Repeatedly applying this transformation to a triangle yields a fractal that looks a bit like a snowflake,
hence the name.
\begin{tikzpicture}[decoration=Koch snowflake,draw=blue,fill=blue!20,thick]
\filldraw (0,0) -- ++(60:1) -- ++(-60:1) -- cycle ;
\filldraw decorate{ (0,-1) -- ++(60:1) -- ++(-60:1) -- cycle };
\filldraw decorate{ decorate{ (0,-2.5) -- ++(60:1) -- ++(-60:1) -- cycle }};
\end{tikzpicture}
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24.3
Decorating a Complete Path
You may sometimes wish to decorate a path over whose construction you have no control. For instance, the
path of the background of a node is created without having a chance to issue a decorate path command.
In such cases you can use the following option, which allows you to decorate a path “after the fact.”
(default true)
/tikz/decorate=hbooleani
When this key is set, the whole path is decorated after it has been finished. The decoration used for
decorating the path is set via the decoration way, in exactly the same way as for the decorate path
command. Indeed, the following two commands have the same effect:
1. \path decorate[hoptionsi] {hpathi};
2. \path [decorate,hoptionsi] hpathi;
The main use or the decorate option is the you can also use it with the nodes. It then causes the
background path of the node to be decorated. Note that you can decorate a background path only once
in this manner. That is, in contrast to the decorate path command you cannot apply this option twice
(this would just set it to true, once more).
\begin{tikzpicture}[decoration=zigzag]
\draw [help lines] (0,0) grid (3,5);
\draw [fill=blue!20,decorate] (1.5,4) circle (1cm);
\node at (1.5,2.5) [fill=red!20,decorate,ellipse] {Ellipse};
\node at (1.5,1) [inner sep=6mm,fill=red!20,decorate,ellipse,decoration=
{text along path,text={This is getting silly}}] {Ellipse};
\end{tikzpicture}
Ellipse
etting silly
s
Thi
is
g
Ellipse
In the last example, the text along path decoration removes the path. In such cases it is useful to use
a pre- or postaction to cause the decoration to be applied only before or after the main path has been
used. Incidentally, this is another application of the decorate option that you cannot achieve with the
decorate path command.
etting silly
s
Thi
is
g
Ellipse
\begin{tikzpicture}[decoration=zigzag]
\node at (1.5,1) [inner sep=6mm,fill=red!20,ellipse,
postaction={decorate,decoration=
{text along path,text={This is getting silly}}}] {Ellipse};
\end{tikzpicture}
u
aro
go
and
aro u n d w
e
24.4.1
d
24.4
ro
d a un
Here is more useful example, where a postaction is used to add the path after the main path has been
drawn.
a n d aro u n d a
\begin{tikzpicture}
n
nd
\draw [help lines] grid (3,2);
\fill [draw=red,fill=red!20,
postaction={decorate,decoration={raise=2pt,text along path,
text=around and around and around and around we go}}]
(0,1) arc (180:-180:1.5cm and 1cm);
\end{tikzpicture}
Adjusting Decorations
Positioning Decorations Relative to the To-Be-Decorate Path
The following option, which are only available with Tik Z, allow you to modify the positioning of decorations
relative to the to-be-decorated path.
354
(no default, initially 0pt)
/pgf/decoration/raise=hdimensioni
The segments of the decoration are raised by hdimensioni relative to the to-be-decorated path. More
precisely, the segments of the path are offset by this much “to the left” of the path as we travel along
the path. This raising is done after and in addition to any transformations set using the transform
option (see below).
A negative hdimensioni will offset the decoration “to the right” of the to-be-decorated path.
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\draw (0,0) -- (1,1) arc (90:0:2 and 1);
\draw
decorate [decoration=crosses]
{ (0,0) -- (1,1) arc (90:0:2 and 1) };
\draw[red] decorate [decoration={crosses,raise=5pt}]
{ (0,0) -- (1,1) arc (90:0:2 and 1) };
\end{tikzpicture}
(no default)
/pgf/decoration/mirror=hbooleani
Causes the segments of the decoration to be mirrored along the to-be-decorated path. This is done after
and in addition to any transformations set using the transform and/or raise options.
B
A
\begin{tikzpicture}
\node (a)
{A};
\node (b) at (2,1) {B};
\draw
\draw[decorate,decoration=brace]
\draw[decorate,decoration={brace,mirror},red]
\draw[decorate,decoration={brace,mirror,raise=5pt},blue]
\end{tikzpicture}
(a)
(a)
(a)
(a)
-----
(b);
(b);
(b);
(b);
(no default)
/pgf/decoration/transform=htransformationsi
This key allows you to specify general htransformationsi to be applied to the segments of a decoration.
These transformations are applied before and independently of raise and mirror transformations. The
htransformationsi should be normal Tik Z transformations like shift or rotate.
In the following example the shift only transformation is used to make sure that the crosses are not
sloped along the path.
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\draw (0,0) -- (1,1) arc (90:0:2 and 1);
\draw[red,very thick] decorate [decoration={
crosses,transform={shift only},shape size=1.5mm}]
{ (0,0) -- (1,1) arc (90:0:2 and 1) };
\end{tikzpicture}
24.4.2
Starting and Ending Decorations Early or Late
You sometimes may wish to “end” a decoration a bit early on the path. For instance, you might wish a snake
decoration to stop 5mm before the end of the path and to continue in a straight line. There are different
ways of achieving this effect, but the easiest may be the pre and post options, which only have an effect in
Tik Z. Note, however, that they can only be used with decorations, not with meta-decorations.
(no default, initially lineto)
/pgf/decoration/pre=hdecorationi
This key sets a decoration that should be used before the main decoration starts. The hdecorationi will
be used for a length of pre length, which 0pt by default. Thus, for the pre option to have any effect,
you also need to set the pre length option.
\begin{tikzpicture}
\tikz [decoration={zigzag,pre=lineto,pre length=1cm}]
\draw [decorate] (0,0) -- (2,1) arc (90:0:1);
\end{tikzpicture}
355
\begin{tikzpicture}
\tikz [decoration={zigzag,pre=moveto,pre length=1cm}]
\draw [decorate] (0,0) -- (2,1) arc (90:0:1);
\end{tikzpicture}
\begin{tikzpicture}
\tikz [decoration={zigzag,pre=crosses,pre length=1cm}]
\draw [decorate] (0,0) -- (2,1) arc (90:0:1);
\end{tikzpicture}
Note that the default pre option is lineto, not curveto. This means that the default pre decoration
will not follow curves (for efficiency reasons). Change the pre key to curveto if you have a curved
path.
\begin{tikzpicture}
\tikz [decoration={zigzag,pre length=3cm}]
\draw [decorate] (0,0) -- (2,1) arc (90:0:1);
\end{tikzpicture}
\begin{tikzpicture}
\tikz [decoration={zigzag,pre=curveto,pre length=3cm}]
\draw [decorate] (0,0) -- (2,1) arc (90:0:1);
\end{tikzpicture}
(no default, initially 0pt)
/pgf/decoration/pre length=hdimensioni
This key sets the distance along which the pre-decoration should be used. If you do not need/wish a
pre-decoration, set this key to 0pt (exactly this string, not just to something that evaluates to the same
things such as 0cm).
(no default, initially lineto)
/pgf/decorations/post=hdecorationi
Works like pre, only for the end of the decoration.
(no default, initially 0pt)
/pgf/decorations/post length=hdimensioni
Works like pre length, only for the end of the decoration.
Here is a typical example that shows how these keys can be used:
\begin{tikzpicture}
[decoration=snake,
line around/.style={decoration={pre length=#1,post length=#1}}]
\draw[->,decorate]
\draw[->,decorate,line around=5pt]
\draw[->,decorate,line around=1cm]
\end{tikzpicture}
356
(0,0)
-- ++(3,0);
(0,-5mm) -- ++(3,0);
(0,-1cm) -- ++(3,0);
25
Transformations
pgf has a powerful transformation mechanism that is similar to the transformation capabilities of metafont.
The present section explains how you can access it in Tik Z.
25.1
The Different Coordinate Systems
It is a long process from a coordinate like, say, (1, 2) or (1cm, 5pt), to the position a point is finally placed
on the display or paper. In order to find out where the point should go, it is constantly “transformed,” which
means that it is mostly shifted around and possibly rotated, slanted, scaled, and otherwise mutilated.
In detail, (at least) the following transformations are applied to a coordinate like (1, 2) before a point on
the screen is chosen:
1. pgf interprets a coordinate like (1, 2) in its xy-coordinate system as “add the current x-vector once
and the current y-vector twice to obtain the new point.”
2. pgf applies its coordinate transformation matrix to the resulting coordinate. This yields the final
position of the point inside the picture.
3. The backend driver (like dvips or pdftex) adds transformation commands such that the coordinate
is shifted to the correct position in TEX’s page coordinate system.
4. pdf (or PostScript) apply the canvas transformation matrix to the point, which can once more change
the position on the page.
5. The viewer application or the printer applies the device transformation matrix to transform the coordinate to its final pixel coordinate on the screen or paper.
In reality, the process is even more involved, but the above should give the idea: A point is constantly
transformed by changes of the coordinate system.
In Tik Z, you only have access to the first two coordinate systems: The xy-coordinate system and the
coordinate transformation matrix (these will be explained later). pgf also allows you to change the canvas
transformation matrix, but you have to use commands of the core layer directly to do so and you “better
know what you are doing” when you do this. The moment you start modifying the canvas matrix, pgf
immediately loses track of all coordinates and shapes, anchors, and bounding box computations will no
longer work.
25.2
The XY- and XYZ-Coordinate Systems
The first and easiest coordinate systems are pgf’s xy- and xyz-coordinate systems. The idea is very simple:
Whenever you specify a coordinate like (2,3) this means 2vx + 3vy , where vx is the current x-vector and vy
is the current y-vector. Similarly, the coordinate (1,2,3) means vx + 2vy + 3vz .
Unlike other packages, pgf does not insist that vx actually has a y-component of 0, that is, that it is a
horizontal vector. Instead, the x-vector can point anywhere you want. Naturally, normally you will want
the x-vector to point horizontally.
One undesirable effect of this flexibility is that it is not possible to provide mixed coordinates as in
(1, 2pt). Life is hard.
To change the x-, y-, and z-vectors, you can use the following options:
(no default, initially 1cm)
/tikz/x=hvaluei
If hvaluei is a dimension, the x-vector of pgf’s xyz-coordinate system is set up to point hvaluei to the
right, that is, to (hvaluei, 0pt).
\begin{tikzpicture}
\draw
(0,0)
-- +(1,0);
\draw[x=2cm,color=red] (0,0.1) -- +(1,0);
\end{tikzpicture}
\tikz \draw[x=1.5cm] (0,0) grid (2,2);
357
The last example shows that the size of steppings in grids, just like all other dimensions, are not affected
by the x-vector. After all, the x-vector is only used to determine the coordinate of the upper right corner
of the grid.
If hvaluei is a coordinate, the x-vector of pgf’s xyz-coordinate system to the specified coordinate. If
hvaluei contains a comma, it must be put in braces.
\begin{tikzpicture}
\draw
(0,0) -- (1,0);
\draw[x={(2cm,0.5cm)},color=red] (0,0) -- (1,0);
\end{tikzpicture}
You can use this, for example, to exchange the meaning of the x- and y-coordinate.
\begin{tikzpicture}[smooth]
\draw plot coordinates{(1,0) (2,0.5) (3,0) (3,1)};
\draw[x={(0cm,1cm)},y={(1cm,0cm)},color=red]
plot coordinates{(1,0) (2,0.5) (3,0) (3,1)};
\end{tikzpicture}
(no default, initially 1cm)
/tikz/y=hvaluei
Works like the x= option, only if hvaluei is a dimension, the resulting vector points to (0, hvaluei).
(no default, initially −3.85mm)
/tikz/z=hvaluei
Works like the y= option, but now a dimension is the point (hvaluei, hvaluei).
\begin{tikzpicture}[z=-1cm,->,thick]
\draw[color=red] (0,0,0) -- (1,0,0);
\draw[color=blue] (0,0,0) -- (0,1,0);
\draw[color=orange] (0,0,0) -- (0,0,1);
\end{tikzpicture}
25.3
Coordinate Transformations
pgf and Tik Z allow you to specify coordinate transformations. Whenever you specify a coordinate as in
(1,0) or (1cm,1pt) or (30:2cm), this coordinate is first “reduced” to a position of the form “x points to the
72
right and y points upwards.” For example, (1in,5pt) is reduced to “72 100
points to the right and 5 points
upwards” and (90:100pt) means “0pt to the right and 100 points upwards.”
The next step is to apply the current coordinate transformation matrix to the coordinate. For example,
the coordinate transformation matrix might currently be set such that it adds a certain constant to the x
value. Also, it might be set up such that it, say, exchanges the x and y value. In general, any “standard”
transformation like translation, rotation, slanting, or scaling or any combination thereof is possible. (Internally, pgf keeps track of a coordinate transformation matrix very much like the concatenation matrix used
by pdf or PostScript.)
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw (0,0) rectangle (1,0.5);
\begin{scope}[xshift=1cm]
\draw
[red]
(0,0) rectangle (1,0.5);
\draw[yshift=1cm] [blue]
(0,0) rectangle (1,0.5);
\draw[rotate=30] [orange] (0,0) rectangle (1,0.5);
\end{scope}
\end{tikzpicture}
The most important aspect of the coordinate transformation matrix is that it applies to coordinates only!
In particular, the coordinate transformation has no effect on things like the line width or the dash pattern or
the shading angle. In certain cases, it is not immediately clear whether the coordinate transformation matrix
should apply to a certain dimension. For example, should the coordinate transformation matrix apply to
358
grids? (It does.) And what about the size of arced corners? (It does not.) The general rule is “If there is no
‘coordinate’ involved, even ‘indirectly,’ the matrix is not applied.” However, sometimes, you simply have to
try or look it up in the documentation whether the matrix will be applied.
Setting the matrix cannot be done directly. Rather, all you can do is to “add” another transformation to
the current matrix. However, all transformations are local to the current TEX-group. All transformations
are added using graphic options, which are described below.
Transformations apply immediately when they are encountered “in the middle of a path” and they apply
only to the coordinates on the path following the transformation option.
\tikz \draw (0,0) rectangle (1,0.5) [xshift=2cm] (0,0) rectangle (1,0.5);
A final word of warning: You should refrain from using “aggressive” transformations like a scaling of a
factor of 10000. The reason is that all transformations are done using TEX, which has a fairly low accuracy.
Furthermore, in certain situations it is necessary that Tik Z inverts the current transformation matrix and
this will fail if the transformation matrix is badly conditioned or even singular (if you do not know what
singular matrices are, you are blessed).
(no default)
/tikz/shift={hcoordinatei}
Adds the hcoordinatei to all coordinates.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (1,1) -- (1,0);
\draw[shift={(1,1)},blue]
(0,0) -- (1,1) -- (1,0);
\draw[shift={(30:1cm)},red] (0,0) -- (1,1) -- (1,0);
\end{tikzpicture}
(no value)
/tikz/shift only
This option does not take any parameter. Its effect is to cancel all current transformations except for
the shifting. This means that the origin will remain where it is, but any rotation around the origin or
scaling relative to the origin or skewing will no longer have an effect.
This option is useful in situations where a complicated transformation is used to “get to a position,” but
you then wish to draw something “normal” at this position.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (1,1) -- (1,0);
\draw[rotate=30,xshift=2cm,blue]
(0,0) -- (1,1) -- (1,0);
\draw[rotate=30,xshift=2cm,shift only,red] (0,0) -- (1,1) -- (1,0);
\end{tikzpicture}
(no default)
/tikz/xshift=hdimensioni
Adds hdimensioni to the x value of all coordinates.
\begin{tikzpicture}
\draw[help lines] (0,0)
\draw
\draw[xshift=2cm,blue]
\draw[xshift=-10pt,red]
\end{tikzpicture}
grid (3,2);
(0,0) -- (1,1) -- (1,0);
(0,0) -- (1,1) -- (1,0);
(0,0) -- (1,1) -- (1,0);
(no default)
/tikz/yshift=hdimensioni
Adds hdimensioni to the y value of all coordinates.
/tikz/scale=hfactor i
(no default)
Multiplies all coordinates by the given hfactor i. The hfactor i should not be excessively large in absolute
terms or very close to zero.
359
\begin{tikzpicture}
\draw[help lines] (0,0) grid
\draw
(0,0) -\draw[scale=2,blue] (0,0) -\draw[scale=-1,red] (0,0) -\end{tikzpicture}
(3,2);
(1,1) -- (1,0);
(1,1) -- (1,0);
(1,1) -- (1,0);
/tikz/scale around={hfactor i:hcoordinatei}
(no default)
Scales the coordinate system by hfactor i, with the “origin of scaling” centered on hcoordinatei rather
than the origin.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (1,1) -- (1,0);
\draw[scale=2,blue]
(0,0) -- (1,1) -- (1,0);
\draw[scale around={2:(1,1)},red] (0,0) -- (1,1) -- (1,0);
\end{tikzpicture}
/tikz/xscale=hfactor i
(no default)
Multiplies only the x-value of all coordinates by the given hfactor i.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (1,1) -- (1,0);
\draw[xscale=2,blue] (0,0) -- (1,1) -- (1,0);
\draw[xscale=-1,red] (0,0) -- (1,1) -- (1,0);
\end{tikzpicture}
/tikz/yscale=hfactor i
(no default)
Multiplies only the y-value of all coordinates by hfactor i.
/tikz/xslant=hfactor i
(no default)
Slants the coordinate horizontally by the given hfactor i:
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (1,1) -- (1,0);
\draw[xslant=2,blue] (0,0) -- (1,1) -- (1,0);
\draw[xslant=-1,red] (0,0) -- (1,1) -- (1,0);
\end{tikzpicture}
/tikz/yslant=hfactor i
(no default)
Slants the coordinate vertically by the given hfactor i:
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (1,1) -- (1,0);
\draw[yslant=2,blue] (0,0) -- (1,1) -- (1,0);
\draw[yslant=-1,red] (0,0) -- (1,1) -- (1,0);
\end{tikzpicture}
360
(no default)
/tikz/rotate=hdegreei
Rotates the coordinate system by hdegreei:
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (1,1) -- (1,0);
\draw[rotate=40,blue] (0,0) -- (1,1) -- (1,0);
\draw[rotate=-20,red] (0,0) -- (1,1) -- (1,0);
\end{tikzpicture}
(no default)
/tikz/rotate around={hdegreei:hcoordinatei}
Rotates the coordinate system by hdegreei around the point hcoordinatei.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (1,1) -- (1,0);
\draw[rotate around={40:(1,1)},blue] (0,0) -- (1,1) -- (1,0);
\draw[rotate around={-20:(1,1)},red] (0,0) -- (1,1) -- (1,0);
\end{tikzpicture}
(no default)
/tikz/rotate around x=hanglei
This key sets the x, y and z vectors of the pgf xyz-coordinate system so that they are rotated by
hanglei around the axis corresponding to the x-vector. The rotation is applied so that when looking
towards the origin along this axis, positive angles result in an anticlockwise rotation.
\begin{tikzpicture}[>=stealth]
\draw [->] (0,0,0) -- (2,0,0) node [at end, right] {$x$};
\draw [->] (0,0,0) -- (0,2,0) node [at end, left] {$y$};
\draw [->] (0,0,0) -- (0,0,2) node [at end, left] {$z$};
y
x
z
\draw [red,
rotate around x=0] (0,0,0) -- (1,1,0) -- (1,0,0);
\draw [green, rotate around x=45] (0,0,0) -- (1,1,0) -- (1,0,0);
\draw [blue, rotate around x=90] (0,0,0) -- (1,1,0) -- (1,0,0);
\end{tikzpicture}
(no default)
/tikz/rotate around y=hanglei
This key sets the x, y and z vectors of the pgf xyz-coordinate system so that they are rotated by
hanglei around the axis corresponding to the y-vector. The rotation is applied so that when looking
towards the origin along this axis, positive angles result in an anticlockwise rotation.
\begin{tikzpicture}[>=stealth]
\draw [->] (0,0,0) -- (2,0,0) node [at end, right] {$x$};
\draw [->] (0,0,0) -- (0,2,0) node [at end, left] {$y$};
\draw [->] (0,0,0) -- (0,0,2) node [at end, left] {$z$};
y
x
z
\draw [red,
rotate around y=0]
(0,0,0) -- (1,1,0) -- (1,0,0);
\draw [green, rotate around y=-45] (0,0,0) -- (1,1,0) -- (1,0,0);
\draw [blue, rotate around y=-90] (0,0,0) -- (1,1,0) -- (1,0,0);
\end{tikzpicture}
(no default)
/tikz/rotate around z=hanglei
This key sets the x, y and z vectors of the pgf xyz-coordinate system so that they are rotated by
hanglei around the axis corresponding to the z-vector. The rotation is applied so that when looking
towards the origin along this axis, positive angles result in an anticlockwise rotation.
361
\begin{tikzpicture}[>=stealth]
\draw [->] (0,0,0) -- (2,0,0) node [at end, right] {$x$};
\draw [->] (0,0,0) -- (0,2,0) node [at end, left] {$y$};
\draw [->] (0,0,0) -- (0,0,2) node [at end, left] {$z$};
y
x
z
\draw [red,
rotate around z=0] (0,0) -- (1,1) -- (1,0);
\draw [green, rotate around z=45] (0,0) -- (1,1) -- (1,0);
\draw [blue, rotate around z=90] (0,0) -- (1,1) -- (1,0);
\end{tikzpicture}
(no default)
/tikz/cm={hai,hbi,hci,hdi,hcoordinatei}
applies the following transformation to all coordinates: Let (x, y) be the coordinate to be transformed
and let hcoordinatei specify the point (tx , ty ). Then the new coordinate is given by ( ab dc ) ( xy ) + ttxy .
Usually, you do not use this option directly.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (1,1) -- (1,0);
\draw[cm={1,1,0,1,(0,0)},blue]
(0,0) -- (1,1) -- (1,0);
\draw[cm={0,1,1,0,(1cm,1cm)},red] (0,0) -- (1,1) -- (1,0);
\end{tikzpicture}
(no value)
/tikz/reset cm
Completely resets the coordinate transformation matrix to the identity matrix. This will destroy not only
the transformations applied in the current scope, but also all transformations inherited from surrounding
scopes. Do not use this option, unless you really, really know what you are doing.
25.4
Canvas Transformations
A canvas transformation, see Section 94.4 for details, is best thought of as a transformation in which the
drawing canvas is stretched or rotated. Imaging writing something on a balloon (the canvas) and then
blowing air into the balloon: Not only does the text become larger, the thin lines also become larger. In
particular, if you scale the canvas by a factor of two, all lines are twice as thick.
Canvas transformations should be used with great care. In most circumstances you do not want line
widths to change in a picture as this creates visual inconsistency.
Just as important, when you use canvas transformations pgf loses track of positions of nodes and of
picture sizes since it does not take the effect of canvas transformations into account when it computes
coordinates of nodes (do not, however, rely on this; it may change in the future).
Finally, note that a canvas transformation always applies to a path as a whole, it is not possible (as for
coordinate transformations) to use different transformations in different parts of a path.
In short, you should not use canvas transformations unless you really know what you are doing.
(no default)
/tikz/transform canvas=hoptionsi
The hoptionsi should contain coordinate transformations options like scale or xshift. Multiple options
can be given, their effects accumulate in the usual manner. The effect of these hoptionsi (immediately)
changes the current canvas transformation matrix. The coordinate transformation matrix is not changed.
Tracking of the picture size is (locally) switched off and the node coordinate will no longer be correct.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (1,1) -- (1,0);
\draw[transform canvas={scale=2},blue]
(0,0) -- (1,1) -- (1,0);
\draw[transform canvas={rotate=180},red] (0,0) -- (1,1) -- (1,0);
\end{tikzpicture}
362
Part IV
Graph Drawing
by Till Tantau et al.
Graph drawing algorithms do the tough work of computing a layout of a graph for you. Tik Z comes with
powerful such algorithms, but you can also implement new algorithms in the Lua programming language.
5th Edition
6th Edition
LSX
Mini Unix
Wollongong
Interdata
7th Edition
32V
Xenix
3 BSD
PWB 1.0
UniPlus+
1 BSD
USG 1.0
CB Unix 1
USG 2.0
CB Unix 2
USG 3.0
2 BSD
PDP-11 Sys V
Ultrix-11
Unix/TS 1.0
Unix/TS 3.0
Unix/TS++
V7M
2.8 BSD
PWB 2.0
CB Unix 3
4 BSD
4.1 BSD
PWB 1.2
TS 4.0
8th Edition
9th Edition
2.9 BSD
4.2 BSD
4.3 BSD
System V.0
Ultrix-32
System V.2
System V.3
\tikz [nodes={text height=.7em, text depth=.2em,
draw=black!20, thick, fill=white, font=\footnotesize},
>=spaced stealth’, rounded corners, semithick]
\graph [layered layout, level distance=1cm, sibling sep=.5em, sibling distance=1cm] {
"5th Edition" -> { "6th Edition", "PWB 1.0" };
"6th Edition" -> { "LSX" [>child anchor=45], "1 BSD", "Mini Unix", "Wollongong", "Interdata" };
"Interdata" -> { "Unix/TS 3.0", "PWB 2.0", "7th Edition" };
"7th Edition" -> { "8th Edition", "32V", "V7M", "Ultrix-11", "Xenix", "UniPlus+" };
"V7M" -> "Ultrix-11";
"8th Edition" -> "9th Edition";
"1 BSD" -> "2 BSD" -> "2.8 BSD" -> { "Ultrix-11", "2.9 BSD" };
"32V" -> "3 BSD" -> "4 BSD" -> "4.1 BSD" -> { "4.2 BSD", "2.8 BSD", "8th Edition" };
"4.2 BSD" -> { "4.3 BSD", "Ultrix-32" };
"PWB 1.0" -> { "PWB 1.2" -> "PWB 2.0", "USG 1.0" -> { "CB Unix 1", "USG 2.0" }};
"CB Unix 1" -> "CB Unix 2" -> "CB Unix 3" -> { "Unix/TS++", "PDP-11 Sys V" };
{ "USG 2.0" -> "USG 3.0", "PWB 2.0", "Unix/TS 1.0" } -> "Unix/TS 3.0";
{ "Unix/TS++", "CB Unix 3", "Unix/TS 3.0" } -> "TS 4.0" -> "System V.0" -> "System V.2" -> "System V.3";
};
363
26
Introduction to Algorithmic Graph Drawing
by Till Tantau
26.1
What Is Algorithmic Graph Drawing?
Algorithmic graph drawing (or just graph drawing in the following) is the process of computing algorithmically
where the nodes of a graph are positioned on a page so that the graph “looks nice.” The idea is that you,
as human (or you, as a machine, if you happen to be a machine and happen to be reading this document)
just specify which nodes are present in a graph and which edges are present. Additionally, you may add
some “hints” like “this node should be near the center” or “this edge is pretty important.” You do not specify
where, exactly, the nodes and edges should be. This is something you leave to a graph drawing algorithm.
The algorithm gets your description of the graph as an input and then decides where the nodes should go
on the page.
4
3
10
0
8
1
6
9
7
Haus
2
N
i
5
as
ko
4
laus
D
1
vom
5
\tikz \graph [binary tree layout, level distance=5mm] {
4 -- {
3 -- 0 -- 1[second],
10 -- {
8 -- {
6 -- {5,7},
9
} } }
};
ist
das
\tikz \graph [spring layout,
edge quotes mid,
edges={nodes={font=\scriptsize, fill=white, sloped, inner sep=1pt}}]
{
1 ->["Das"] 2 ->["ist"] 3 ->["das"] 4 ->["Haus"]
2 ->["vom" near start] 5 ->["Ni"] 4 ->["ko" near start]
1 ->["laus", orient=right] 5;
};
3
Naturally, graph drawing is a bit of a (black?) art. There is no “perfect” way of drawing a graph, rather,
depending on the circumstances there are several different ways of drawing the same graph and often it will
just depend on the aesthetic sense of the reader which layout he or she would prefer. For this reason, there
are a huge number of graph drawing algorithms “out there” and there are scientific conference devoted to
such algorithms, where each year dozens of new algorithms are proposed.
Unlike the rest of pgf and Tik Z, which is implemented purely in TEX, the graph drawing algorithms
are simply too complex to be implemented directly in TEX. Instead, the programming language Lua is used
by the graph drawing library – a programming language that has been integrated into recent versions of
TEX. This means that (a) as a user of the graph drawing engine you run TEX on your documents in the
usual way, no external programs are called since Lua is already integrated into TEX, and (b) it is pretty
easy to implement new graph drawing algorithms for Tik Z since Lua can be used and no TEX programming
knowledge is needed.
26.2
Using the Graph Drawing System
“Users” of the graph drawing engine can invoke the graph drawing algorithms often by just adding a single
option to their picture. Here is a typical example, where the layered layout option tells Tik Z that the
graph should be drawn (“should be layed out”) using a so-called “layered graph drawing algorithm” (what
these are will be explained later):
364
first root
1
second root
x
6
2
3
third root
a
7
c
b
u
4
child
v
grandchild
youngster
d
w
5
z
\tikz [>=spaced stealth’]
\graph [layered layout, components go right top aligned, nodes=draw, edges=rounded corners]
{
first root -> {1 -> {2, 3, 7} -> {4, 5}, 6 }, 4 -- 5;
second root -> x -> {a -> {u,v}, b, c -> d -> {w,z} };
third root -> child -> grandchild -> youngster -> third root;
};
Here is another example, where a different layout method is used that is more appropriate for trees:
5
3
6
9
4
8
2
7
1
\tikz [grow’=up, binary tree layout, nodes={circle,draw}]
\node {1}
child { node {2}
child { node {3} }
child { node {4}
child { node {5} }
child { node {6} }
}
}
child { node {7}
child { node {8}
child[missing]
child { node {9} }
}
};
A final example, this time using a “spring electrical layout” (whatever that might be. . . ):
\tikz [spring electrical layout, node distance=1.3cm,
every edge/.style={
decoration={coil, aspect=-.5, post length=1mm,
segment length=1mm, pre length=2mm},
decorate, draw}]
{
\foreach \i in {1,...,6}
\node (node \i) [fill=blue!50, text=white, circle] {\i};
1
2
4
\draw (node 1) edge
(node 2) edge
edge
(node 3) edge
edge
edge
3
6
5
(node
(node
(node
(node
(node
(node
2)
3)
4)
4)
5)
6);
}
In all of the example, the positions of the nodes have only been computed after all nodes have
been created and the edges have been specified. For instance, in the last example, without the option
spring electrical layout, all of the nodes would have been placed on top of each other.
26.3
Extending the Graph Drawing System
The graph drawing engine is also intended to make is (relatively) easy to implement new graph drawing
algorithms. These algorithms can either be implemented in the Lua programming language (which is much
easier to program than TEX itself) or in C/C++ (but at a great cost regarding portability). The Lua code
for a graph drawing algorithm gets an object-oriented model of the input graph as an input and must just
365
compute the desired new positions of the nodes. The complete handling of passing options and configurations
back-and-forth between the different Tik Z and pgf layers is handled by the graph drawing engine.
As a caveat, the graph drawing engine comes with a library of functions and methods that simplify the
writing of new graph drawing algorithms. As a typical example, when you implement a graph drawing
algorithm for trees, you typically require that your input is a tree; but you can bet that users will feed all
sorts of graphs to your algorithm, including disjoint unions of cliques. The graph drawing engine offers you
to say that a precondition to running your algorithm is that the graph is a tree and instead of the original
graph your algorithm will be provided with a spanning tree of the graph on which it can work. There are
numerous further automatic pre- and postprocessing steps that include orienting, anchoring, and packing of
components, to name a few.
The bottom line is that the graph drawing engine makes it easy to try out new graph drawing algorithms
for medium sized graphs (up to a few hundred nodes) in Lua. For larger graphs, C/C++ code must be used.
26.4
The Layers of the Graph Drawing System
Even though the graph drawing system presented in the following sections was developed as part of pgf, it
can be used independently of pgf and Tik Z: It was (re)designed so that it can be used by arbitrary programs
as long as they are able to run Lua. To achieve this, the graph drawing system consists of three layers:
1. At the “bottom” we have the algorithmic layer. This layer, written in Lua, contains all graph drawing
algorithms. Interestingly, options must also be declared on this layer, so an algorithm together with
all options it uses can and must be specified entirely on this layer. If you intend to implement a new
graph drawing algorithm, you will only be interested in the functionality of this layer.
Algorithm “communicate” with the graph drawing system through a well-defined interface, encapsulated
in the class InterfaceToAlgorithms.
2. At the “top” we have the display layer. This layer is not actually part of the graph drawing system.
Rather, it is a piece of software that “displays” graphs and Tik Z is just one example of such a software.
Another example might be a graph editor that uses the graph drawing system to lay out the graph
it displays. Yet another example might be a command line tool for drawing graphs described in a
file. Finally, you may also wish to use the graph drawing system as a simple subroutine for rendering
graphs produced in a larger program.
Since the different possible instantiations of the display layer are quite heterogeneous, all display layers
must communicate with the graph drawing system through a special interface, encapsulated in the
class InterfaceToDisplay.
The main job of this class is to provide a set of methods for specifying that a graph has certain nodes
and edges and that certain options have been set for them. However, this interface also allows you to
query all options that have been declared by algorithms, including their documentation. This way, an
editor or a command line tool can display a list of all graph drawing algorithms and how they can be
configured.
3. The algorithm layer and the display layer are “bound together” through the binding layer. Most of the
bookkeeping concerning the to-be-drawn graphs is done by the graph drawing system independently of
which algorithm is used and also independently of which display layer is used, but some things are still
specific to each display layer. For instance, some algorithms may create new nodes and the algorithms
may then need to know how large these nodes will be. For this, the display layer must be “queried”
during a run of the algorithm – and it is the job of the binding layer to achieve this callback.
As a rule, the binding layer implements the “backward” communication from the graph drawing system
back to the display layer, while the display layer’s interface class provides only functions that are called
from the display layer but which will not “talk back”.
All of the files concerned with graph drawing reside in the graphdrawing subdirectory of generic/pgf.
26.5
Organisation of the Graph Drawing Documentation
The documentation of the graph drawing engine is structured as follows:
1. Following this overview section, the next section documents the graph drawing engine from “the Tik Z
user’s point of view”. No knowledge of Lua or algorithmic graph drawing is needed for this section,
everyone who intends to use algorithmic graph drawing in Tik Z may be interested in reading it.
366
2. You will normally only use Tik Z’s keys and commands in order to use the graph drawing system, but,
internally, these keys call more basic pgf commands that do the “hard work” of binding the world of
TEX boxes and macros to the object-oriented world of Lua. Section 28 explains how this works and
which commands are available for authors of packages that directly need to use the graph drawing
system inside pgf, avoiding the overhead incurred by Tik Z.
Most readers can safely skip this section.
3. The next sections detail which graph drawing algorithms are currently implemented as part of the
Tik Z distribution, see Sections 29 to 34.
4. Section 35 is addressed at readers who wish to implement their own graph drawing algorithms. For
this, no knowledge at all of TEX programming is needed. The section explains the graph model used
in Lua, the available libraries, the graph drawing pipeline, and everything else that is part of the Lua
side of the engine.
5. Section 37 details the display layer of the graph drawing system. You should read this section if you
wish to implement a new display system (that is, a non-TEX-based program) that intends to use the
graph drawing system.
6. Section 38 explains how binding layers can be implemented. This section, too, is of interest only to
readers who wish to write new display systems.
26.6
Acknowledgements
Graph drawing in Tik Z began as a student’s project under my supervision. Renée Ahrens, Olof-Joachim
Frahm, Jens Kluttig, Matthias Schulz, and Stephan Schuster wrote the first prototype of a graph drawing
system inside Tik Z that uses LuaTEX for the implementation of graph drawing algorithms.
This first, early version was greatly extended on the algorithmic side by Jannis Pohlmann who wrote
his Diploma thesis on graph drawing under my supervision. He implemented, in particular, the Sugiyama
method (layered layout) and force based algorithms. Also, he rewrote some of the code of the prototype.
At some point it became apparent that the first implementation had a number of deficiencies, both
concerning the structure, the interfaces, and (in particular) the performance. Because of this, I rewrote the
code of the graph drawing system, both on the TEX side and on the Lua side in its current form. However, I
would like to stress that without the work of the people mentioned above graph drawing in Tik Z would not
exist.
The documentation was written almost entirely by myself, though I did copy some paragraphs from
Jannis’s Diploma thesis, which I can highly recommend everyone to read.
In the future, I hope that other people will contribute algorithms, which will be available as libraries.
367
27
Using Graph Drawing in Tik Z
by Till Tantau
Tik Z Library graphdrawing
\usetikzlibrary{graphdrawing} % LATEX and plain TEX
\usetikzlibrary[graphdrawing] % ConTEXt
This package provides capabilities for automatic graph drawing. It requires that the document is typeset
using LuaTEX. This package should work with LuaTEX 0.54 or higher.
27.1
Choosing a Layout and a Library
The graph drawing engine is initialized when you load the library graphdrawing. This library provides the
basic framework for graph drawing, including all options and keys described in the present section. However,
this library does not load any actual algorithms for drawing graphs. For this, you need to use the following
command, which is defined by the graphdrawing library:
\usegdlibrary{hlist of librariesi}
This command is used to load the special graph drawing libraries (the gd in the name of the command
stands for “graph drawing”). The hlist of librariesi is a comma-separated list of library written in the
Lua programming language (which is why a special command is needed).
In detail, this command does the following. For each hnamei in the hlist of librariesi we do:
1. Check whether LuaTEX can call require on the library file pgf.gd.hnamei.library. LuaTEX’s
usual file search mechanism will search the texmf-trees in the usual manner and the dots in the file
name get converted into directory slashes.
2. If the above failed, try to require the string pgf.gd.hnamei.
3. If this fails, try to require the string hnamei.library.
4. If this fails, try to require the string hnamei. If this fails, print an error message.
The net effect of the above is the following: Authors of graph drawing algorithms can bundle together
multiple algorithms in a library by creating a ...xyz/library.lua file that internally just calls require
for all files containing declarations. On the other hand, if a graph drawing algorithm completely fits
inside a single file, it can also be read directly using \usegdlibrary.
\usetikzlibrary{graphdrawing}
\usegdlibrary{trees,force}
The different graph drawing libraries are documented in the following Sections 29 to 34.
Note that in addition to the graph drawing libraries, you may also wish to load the normal Tik Z library
graphs. It provides the powerful graph path command with its easy-to-use syntax for specifying graphs,
but you can use the graph drawing engine independently of the graphs library, for instance in conjunction
with the child or the edge syntax. Here is a typical setup:
\usetikzlibrary{graphs, graphdrawing}
\usegdlibrary{trees, layered}
Having set things up, you must then specify for which scopes the graph drawing engine should apply a
layout algorithm to the nodes in the scope. Typically, you just add an option ending with ... layout to
the graph path operation and then let the graph drawing do its magic:
a
c
d
b
e
f
\tikz [rounded corners]
\graph [layered layout, sibling distance=8mm, level distance=8mm]
{
a -> {
b,
c -> { d, e }
} ->
f ->
a
};
Whenever you use such an option, you can:
368
• Create nodes in the usual way. The nodes will be created completely, but then tucked away in an
internal table. This means that all of Tik Z’s options for nodes can be applied. You can also name a
node and reference it later.
• Create edges using either the syntax of the graph command (using --, <-, ->, or <->), or using the
edge command, or using the child command. These edges will, however, not be created immediately. Instead, the basic layer’s command \pgfgdedge will be called, which stores “all the information
concerning the edge.” The actual drawing of the edge will only happen after all nodes have been
positioned.
• Most of the keys that can be passed to an edge will work as expected. In particular, you can add labels
to edges using the usual node syntax for edges.
• The label and pin options can be used in the usual manner with nodes inside a graph drawing scope.
Only, the labels and nodes will play no role in the positioning of the nodes and they are added when
the nodes are finally positioned.
• Similarly, nodes that are placed “on an edge” using the implicit positioning syntax can be used in the
usual manner.
Here are some things that will not work:
• Only edges created using the graph syntax, the edge command, or the child command will correctly
pass their connection information to the basic layer. When you write \draw (a)--(b); inside a graph
drawing scope, where a and b are nodes that have been created inside the scope, you will get an error
message / things will look wrong. The reason is that the usual -- is not “caught” by the graph drawing
engine and, thus, tries to immediately connect two nodes that do not yet exist (except inside some
internal table).
• The options of edges are executed twice: Once when the edge is “examined” by the \pgfgdedge
command (using some magic to shield against the side effects) and then once more when the edge is
actually created. Fortunately, in almost all cases, this will not be a problem; but if you do very evil
magic inside your edge options, you must roll a D100 to see what strange things will happen. (Do no
evil, by the way.)
If you are really interested in the “fine print” of what happens, please see Section 28.
27.2
Graph Drawing Parameters
Graph drawing algorithms can typically be configured in some way. For instance, for a graph drawing
algorithm that visualizes its nodes as a tree, it will typically be useful when the user can change the so-called
level distance and the sibling distance. For other algorithms, like force-based algorithms, a large number of
parameters influence the way the algorithms work. Options that influence graph drawing algorithms will be
called (graph drawing) parameters in the following. From the user’s point of view, these parameters look
like normal Tik Z keys and you set them in the usual way. Internally, they are treated a bit differently from
normal keys since their “effect” becomes apparent only later on, namely during the run of the graph drawing
algorithm.
A graph drawing algorithm may or may not take different graph parameters into account. After all, these
options may even outright contradict each other, so an algorithm can only try to “do its best”. While many
graph parameters are very specific to a single algorithm, a number of graph parameters will be important
for many algorithms and they are documented in the course of the present section. Here is an example of
an option the “always works”:
1
\tikz \graph [spring layout, vertical=1 to 2] { 1--2--3--1 };
3
2
369
27.3
Padding and Node Distances
In many drawings, you may wish to specify how “near” two nodes should be placed by a graph drawing
algorithm. Naturally, this depends strongly on the specifics of the algorithm, but there are a number of
general keys that will be used by many algorithms.
There are different kinds of objects for which you can specify distances and paddings:
• You specify the “natural” distance between nodes connected by an edge using node distance, which
is also available in normal Tik Z albeit for a slightly different purpose. However, not every algorithm
will (or can) honour the key; see the description of each algorithm what it will “make of this option”.
• A number of graph drawing algorithms arrange nodes in layers (or levels); we refer to the nodes on the
same layer as siblings (although, in a tree, siblings are only nodes with the same parent; nevertheless
we use “sibling” loosely also for nodes that are more like “cousins”).
• When a graph consists of several connected component, many graph drawing algorithms will layout
these components individually. The different components will then be arranged next to each other, see
Section 27.7 for the details, such that between the nodes of any two components a padding is avaiable.
/graph drawing/node distance=hlengthi
(initially 1cm)
This is minimum distance that the centers of nodes connected by an edge should have. It will not always
be possible to satisfy this desired distance, for instance in case the nodes are too big. In this case, the
hlengthi is just considered as a lower bound.
Example
.
\begin{tikzpicture}
\graph [simple necklace layout, node distance=1cm, node sep=0pt,
nodes={draw,circle,as=.}]
{
1 -- 2 [minimum size=2cm] -- 3 -4 -- 5 -- 6 -- 7 --[orient=up] 8
};
\draw [red,|-|] (1.center) -- ++(0:1cm);
\draw [red,|-|] (5.center) -- ++(180:1cm);
\end{tikzpicture}
.
.
.
.
.
.
.
(initially .333em)
/graph drawing/node pre sep=hlengthi
This is a minimum “padding” or “separation” between the border of nodes connected by an edge. Thus,
if nodes are so big that nodes with a distance of node distance would overlap (or just come with
hdimensioni distance of one another), their distance is enlarged so that this distance is still satisfied.
The pre means that the padding is added to the node “at the front.” This make sense only for some
algorithms, like for a simple necklace layout.
Examples
1
2
5
3
2
\tikz \graph [simple necklace layout, node distance=0cm, nodes={circle,draw}]
{ 1--2--3--4--5--1 };
4
1
3
5
4
\tikz \graph [simple necklace layout, node distance=0cm, node sep=0mm,
nodes={circle,draw}]
{ 1--2--3[node pre sep=5mm]--4--5[node pre sep=1mm]--1 };
(initially .333em)
/graph drawing/node post sep=hlengthi
Works like node pre sep.
370
/graph drawing/node sep=hlengthi
A shorthand for setting both node pre sep and node post sep to hlengthi/2.
(initially 1cm)
/graph drawing/level distance=hlengthi
This is minimum distance that the centers of nodes on one level should have from the centers of nodes
on the next level. It will not always be possible to satisfy this desired distance, for instance in case the
nodes are too big. In this case, the hlengthi is just considered as a lower bound.
Example
1
1
\begin{tikzpicture}[inner sep=2pt]
\draw [help lines] (0,0) grid (3.5,2);
\graph [layered layout, level distance=1cm, level sep=0]
{ 1 [x=1,y=2] -- 2 -- 3 -- 1 };
\graph [layered layout, level distance=5mm, level sep=0]
{ 1 [x=3,y=2] -- 2 -- 3 -- 1, 3 -- {4,5} -- 6 -- 3 };
\end{tikzpicture}
2
3
2
4
5
3
6
/graph drawing/layer distance=hlengthi
An alias for level distance
(initially .333em)
/graph drawing/level pre sep=hlengthi
This is a minimum “padding” or “separation” between the border of the nodes on a level to any nodes on
the previous level. Thus, if nodes are so big that nodes on consecutive levels would overlap (or just come
with hlrngthi distance of one another), their distance is enlarged so that this distance is still satisfied.
If a node on the previous level also has a level post sep, this post padding and the hdimensioni add
up. Thus, these keys behave like the “padding” keys rather than the “margin” key of cascading style
sheets.
Example
1
2
2
3
5
1
3
4
4
5
\begin{tikzpicture}[inner sep=2pt, level sep=0pt, sibling distance=0pt]
\draw [help lines] (0,0) grid (3.5,2);
\graph [layered layout, level distance=0cm, nodes=draw]
{ 1 [x=1,y=2] -- {2,3[level pre sep=1mm],4[level pre sep=5mm]} -- 5 };
\graph [layered layout, level distance=0cm, nodes=draw]
{ 1 [x=3,y=2] -- {2,3,4} -- 5[level pre sep=5mm] };
\end{tikzpicture}
(initially .333em)
/graph drawing/level post sep=hlengthi
Works like level pre sep.
/graph drawing/layer pre sep=hlengthi
An alias for level pre sep.
/graph drawing/layer post sep=hlengthi
An alias for level post sep.
/graph drawing/level sep=hlengthi
A shorthand for setting both level pre sep and level post sep to hlengthi/2. Note that if you set
level distance=0 and level sep=1em, you get a layout where any two consecutive layers are “spaced
apart” by 1em.
/graph drawing/layer sep=hnumber i
An alias for level sep.
(initially 1cm)
/graph drawing/sibling distance=hlengthi
This is minimum distance that the centers of node should have to the center of the next node on the
same level. As for levels, this is just a lower bound. For some layouts, like a simple necklace layout, the
hlengthi is measured as the distance on the circle.
371
Examples
1
2
\tikz \graph [tree layout, sibling distance=1cm, nodes={circle,draw}]
{ 1--{2,3,4,5} };
3
4
5
1
2
3
4
5
1
2
3
4
5
\tikz \graph [tree layout, sibling distance=0cm, sibling sep=0pt,
nodes={circle,draw}]
{ 1--{2,3,4,5} };
\tikz \graph [tree layout, sibling distance=0cm, sibling sep=0pt,
nodes={circle,draw}]
{ 1--{2,3[sibling distance=1cm],4,5} };
(initially .333em)
/graph drawing/sibling pre sep=hlengthi
Works like level pre sep, only for siblings.
Example
1
2
3
4
5
\tikz \graph [tree layout, sibling distance=0cm, nodes={circle,draw},
sibling sep=0pt]
{ 1--{2,3[sibling pre sep=1cm],4,5} };
(initially .333em)
/graph drawing/sibling post sep=hlengthi
Works like sibling pre sep.
/graph drawing/sibling sep=hlengthi
A shorthand for setting both sibling pre sep and sibling post sep to hlengthi/2.
(initially 1.5cm)
/graph drawing/part distance=hlengthi
This is minimum distance between the centers of “parts” of a graph. What a “part” is depends on the
algorithm.
(initially 1em)
/graph drawing/part pre sep=hlengthi
A pre-padding for parts.
(initially 1em)
/graph drawing/part post sep=hlengthi
A post-padding for pars.
/graph drawing/part sep=hlengthi
A shorthand for setting both part pre sep and part post sep to hlengthi/2.
(initially 1.5em)
/graph drawing/component sep=hlengthi
This is pading between the bounding boxes that nodes of different connected components will have when
they are placed next to each other.
Examples
1 a
2
3
6
y
b
7 c z
4
5
x
u
d
e
\tikz \graph [binary tree layout, sibling distance=4mm, level distance=8mm,
components go right top aligned,
component sep=1pt, nodes=draw]
{
1 -> 2 -> {3->4[second]->5,6,7};
a -> b[second] -> c[second] -> d -> e;
x -> y[second] -> z -> u[second] -> v;
};
v
372
a
1
2
3
6
x
y
b
c
7
4
z
u
d
e
5
\tikz \graph [binary tree layout, sibling distance=4mm, level distance=8mm,
components go right top aligned,
component sep=1em, nodes=draw]
{
1 -> 2 -> {3->4[second]->5,6,7};
a -> b[second] -> c[second] -> d -> e;
x -> y[second] -> z -> u[second] -> v;
};
v
(initially 2cm)
/graph drawing/component distance=hlengthi
This is the minimum distance between the centers of bounding boxes of connected components when
they are placed next to each other. (Not used, currently.)
27.4
Anchoring a Graph
A graph drawing algorithm must compute positions of the nodes of a graph, but the computed positions
are only relative (“this node is left of this node, but above that other node”). It is not immediately obvious
where the “the whole graph” should be placed absolutely once all relative positions have been computed. In
case that the graph consists of several unconnected components, the situation is even more complicated.
The order in which the algorithm layer determines the node at which the graph should be anchored:
1. If the anchor node=hnode namei option given to the graph as a whole, the graph is anchored at hnode
namei, provided there is a node of this name in the graph. (If there is no node of this name or if it is
misspelled, the effect is the same as if this option had not been given at all.)
2. Otherwise, if there is a node where the anchor here option is specified, the first node with this option
set is used.
3. Otherwise, if there is a node where the desired at option is set (perhaps implicitly through keys like
x), the first such node is used.
4. Finally, in all other cases, the first node is used.
In the above description, the “first” node refers to the node first encountered in the specification of the
graph.
Once the node has been determined, the graph is shifted so that this node lies at the poistion specified
by anchor at.
/graph drawing/desired at=hcoordinatei
When you add this key to a node in a graph, you “desire” that the node should be placed at the
hcoordinatei by the graph drawing algorithm. Now, when you set this key for a single node of a graph,
then, by shifting the graph around, this “wish” can obviously always be fulfill:
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\graph [spring layout]
{
a [desired at={(1,2)}] -- b -- c -- a;
};
\end{tikzpicture}
a
c
b
a
c
b
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\graph [spring layout]
{
a -- b[desired at={(2,1)}] -- c -- a;
};
\end{tikzpicture}
373
Since the key’s name is a bit long and since the many braces and parentheses are a bit cumbersome,
there is a special support for this key inside a graph: The standard /tikz/at key is redefined inside a
graph so that it points to /graph drawing/desired at instead. (Which is more logical anyway, since
it makes no sense to specify an at position for a node whose position it to be computed by a graph
drawing algorithm.) A nice side effect of this is that you can use the x and y keys (see Section 19.9.1)
to specify desired positions:
a
c
b
a
c
b
e
f
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\graph [spring layout]
{
a -- b[x=2,y=0] -- c -- a;
};
\end{tikzpicture}
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\graph [layered layout]
{
a [x=1,y=2] -- { b, c } -- {e, f} -- a
};
\end{tikzpicture}
A problem arises when two or more nodes have this key set, because then your “desires” for placement
and the positions computed by the graph drawing algorithm may clash. Graph drawing algorithms are
“told” about the desired positions. Most algorithms will simply ignore these desired positions since they
will be taken care of in the so-called post-anchoring phase, see below. However, for some algorithms it
makes a lot of sense to fix the positions of some nodes and only compute the positions of the other nodes
relative to these nodes. For instance, for a spring layout it makes perfect sense that some nodes are
“nailed to the canvas” while other nodes can “move freely”.
Examples
g
f
d
e
a
h
c
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\graph [spring layout]
{
a[x=1] -- { b, c, d, e -- {f,g,h} };
{ h, g } -- a;
};
\end{tikzpicture}
b
d
h
a
b
f
e
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\graph [spring layout]
{
a -- { b, c, d[x=0], e -- {f[x=2], g, h[x=1]} };
{ h, g } -- a;
};
\end{tikzpicture}
g
c
374
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\graph [spring layout]
{
a -- { b, c, d[x=0], e -- {f[x=2,y=1], g, h[x=1]} };
{ h, g } -- a;
};
\end{tikzpicture}
f
d
e
h
g
a
b
c
/graph drawing/anchor node=hstringi
This option can be used with a graph to specify a node that should be used for anchoring the whole
graph. When this option is specified, after the layout has been computed, the whole graph will be
shifted in such a way that the hnode namei is either
• at the current value of anchor at or
• at the position that is specified in the form of a desired at for the hnode namei.
Note how in the last example c is placed at (1,1) rather than b as would happen by default.
Examples
x
a
y
z
c
b
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
d
b
\tikz \draw (0,0)
-- (1,0.5) graph [edges=red, layered layout, anchor node=a] { a -> {b,c} }
-- (1.5,0) graph [edges=blue, layered layout,
anchor node=y, anchor at={(2,0)}]
{ x -> {y,z} };
\graph [layered layout, anchor node=c, edges=rounded corners]
{ a -- {b [x=1,y=1], c [x=1,y=1] } -- d -- a};
\end{tikzpicture}
c
a
/graph drawing/anchor at=hcanvas coordinatei
(initially (0pt,0pt))
The coordinate at which the graph should be anchored when no explicit anchor is given for any node.
The initial value is the origin.
Example
a
b
\begin{tikzpicture}
\draw [help lines] (0,0) grid (2,2);
\graph [layered layout, edges=rounded corners, anchor at={(1,2)}]
{ a -- {b, c [anchor here] } -- d -- a};
\end{tikzpicture}
c
d
(default true)
/graph drawing/anchor here=hbooleani
This option can be passed to a single node (rather than the graph as a whole) in order to specify that
this node should be used for the anchoring process. In the example, c is placed at the origin since this
is the default anchor at position.
Example
375
\begin{tikzpicture}
\draw [help lines] (0,0) grid (2,2);
a
\graph [layered layout, edges=rounded corners]
{ a -- {b, c [anchor here] } -- d -- a};
\end{tikzpicture}
c
b
d
27.5
Orienting a Graph
Just as a graph drawing algorithm cannot know where a graph should be placed on a page, it is also often
unclear which orientation it should have. Some graphs, like trees, have a natural direction in which they
“grow”, but for an “arbitrary” graph the “natural orientation” is, well, arbitrary.
There are two ways in which you can specify an orientation: First, you can specify that the line from a
certain vertex to another vertex should have a certain slope. How these vertices and slopes are specified in
explained momentarily. Second, you can specify a so-called “growth direction” for trees.
(default 0)
/graph drawing/orient=hdirectioni
This key specifies that the straight line from the orient tail to the orient head should be at an
angle of hdirectioni relative to the right-going x-axis. Which vertices are used as tail an head depends
on where the orient option is encountered: When used with an edge, the tail is the edge’s tail und the
head is the edge’s head. When used with a node, the tail or the head must be specified explicitly and
the node is used as the node missing in the specification. When used with a graph as a whole, both the
head and tail nodes must be specified explicitly.
Note that the hdirectioni is independent of the actual to-path of an edge, which might define a bend
or more complicated shapes. For instance, a hanglei of 45 requests that the end node is “up and right”
relative to the start node.
You can also specify the standard direction texts north or south east and so forth as hdirectioni and
also up, down, left, and right. Also, you can specify - for “right” and | for “down.”
Examples
c
b
d
a
h
e
\tikz \graph [spring layout]
{
a -- { b, c, d, e -- {f, g, h} };
h -- [orient=30] a;
};
g
f
c
b
a
h
e
d
\tikz \graph [spring layout]
{
a -- { b, c, d[> orient=right], e -- {f, g, h} };
h -- a;
};
g
f
(default 0)
/graph drawing/orient’=hdirectioni
Same as orient, only the rest of the graph should be flipped relative to the connection line.
Example
376
f
g
e
h
a
c
d
\tikz \graph [spring layout]
{
a -- { b, c, d[> orient’=right], e -- {f, g, h} };
h -- a;
};
b
/graph drawing/orient tail=hstringi
Specifies the tail vertex for the orientation of a graph. See orient for details.
Examples
f
e
h
\tikz \graph [spring layout] {
a [orient=|, orient tail=f] -- { b, c, d, e -- {f, g, h} };
{ h, g } -- a;
};
g
a
c
d
b
f
h
e
c
a
g
\tikz \graph [spring layout] {
a [orient=down, orient tail=h] -- { b, c, d, e -- {f, g, h} };
{ h, g } -- a;
};
b
d
/graph drawing/orient head=hstringi
Specifies the head vertex for the orientation of a graph. See orient for details.
Examples
b
c
d
a
g
h
e
\tikz \graph [spring layout]
{
a [orient=|, orient head=f] -- { b, c, d, e -- {f, g, h} };
{ h, g } -- a;
};
f
a
b
a
c
b
\tikz \graph [spring layout] { a -- b -- c -- a };
\tikz \graph [spring layout, orient=10,
orient tail=a, orient head=b] { a -- b -- c -- a };
c
/graph drawing/horizontal=hstringi
A shorthand for specifying orient tail, orient head and orient=0. The tail will be everything before
the part “ to ” and the head will be everything following it.
Example
377
a
a
b
c
b
\tikz \graph [spring layout]
{ a -- b -- c -- a };
\tikz \graph [spring layout, horizontal=a to b] { a -- b -- c -- a };
c
/graph drawing/horizontal’=hstringi
Like horizontal, but with a flip.
/graph drawing/vertical=hstringi
A shorthand for specifying orient tail, orient head and orient=-90.
Example
a
a
\tikz \graph [spring layout]
{ a -- b -- c -- a };
\tikz \graph [spring layout, vertical=a to b] { a -- b -- c -- a };
c c
b
b
/graph drawing/vertical’=hstringi
Like vertical, but with a flip.
/graph drawing/grow=hdirectioni
This key specifies in which direction the neighbors of a node “should grow.” For some graph drawing
algorithms, especially for those that layout trees, but also for those that produce layered layouts, there is
a natural direction in which the “children” of a node should be placed. For instance, saying grow=down
will cause the children of a node in a tree to be placed in a left-to-right line below the node (as
always, you can replace the hanglei by direction texts). The children are requested to be placed in a
counter-clockwise fashion, the grow’ key will place them in a clockwise fashion.
Note that when you say grow=down, it is not necessarily the case that any particular node is actually
directly below the current node; the key just requests that the direction of growth is downward.
In principle, you can specify the direction of growth for each node individually, but do not count on
graph drawing algorithms to honour these wishes.
When you give the grow=right key to the graph as a whole, it will be applied to all nodes. This happens
to be exactly what you want:
Examples
h
a
g
e
d
f
\tikz \graph [layered layout, sibling distance=5mm]
{
a [grow=right] -- { b, c, d, e -- {f, g, h} };
{ h, g } -- a;
};
c
b
h
a
g
e
d
f
\tikz \graph [layered layout, grow=right, sibling distance=5mm]
{
a -- { b, c, d, e -- {f, g, h} };
{ h, g } -- a;
};
c
b
378
c
b
a
f
d
e
i
h
g
\tikz
\graph [layered layout, grow=-80]
{
{a,b,c} --[complete bipartite] {e,d,f}
--[complete bipartite] {g,h,i};
};
/graph drawing/grow’=hdirectioni
Same as grow, only with the children in clockwise order.
Example
b
c
d
f
e
a
\tikz \graph [layered layout, sibling distance=5mm]
{
a [grow’=right] -- { b, c, d, e -- {f, g, h} };
{ h, g } -- a;
};
g
h
27.6
Fine-Tuning Positions of Nodes
/graph drawing/nudge=hcanvas coordinatei
This option allows you to slightly “nudge” (move) nodes after they have been positioned by the given
offset. The idea is that this nudging is done after the position of the node has been computed, so
nudging has no influence on the actual graph drawing algorithms. This, in turn, means that you can use
nudging to “correct” or “optimize” the positioning of nodes after the algorithm has computed something.
Example
a
b
c
d
\tikz \graph [edges=rounded corners, nodes=draw,
layered layout, sibling distance=0] {
a -- {b, c, d[nudge=(up:2mm)]} -- e -- a;
};
e
/graph drawing/nudge up=hlengthi
A shorthand for nudging a node upwards.
Example
a
b
c
d
\tikz \graph [edges=rounded corners, nodes=draw,
layered layout, sibling distance=0] {
a -- {b, c, d[nudge up=2mm]} -- e -- a;
};
e
/graph drawing/nudge down=hlengthi
Like nudge up, but downwards.
/graph drawing/nudge left=hlengthi
Like nudge up, but left.
379
Example
a
\tikz \graph [edges=rounded corners, nodes=draw,
layered layout, sibling distance=0] {
a -- {b, c, d[nudge left=2mm]} -- e -- a;
};
c d
b
e
/graph drawing/nudge right=hlengthi
Like nudge left, but right.
/graph drawing/regardless at=hcanvas coordinatei
Using this option you can provide a position for a node to wish it will be forced after the graph algorithms
have run. So, the node is positioned normally and the graph drawing algorithm does not know about
the position specified using regardless at. However, afterwards, the node is placed there, regardless
of what the algorithm has computed (all other nodes are unaffected).
Example
a
b
d
c
\tikz \graph [edges=rounded corners, nodes=draw,
layered layout, sibling distance=0] {
a -- {b,c,d[regardless at={(1,0)}]} -- e -- a;
};
e
/graph drawing/nail at=hcanvas coordinatei
This option combines desired at and regardless at. Thus, the algorithm is “told” about the desired
position. If it fails to place the node at the desired position, it will be put there regardless. The name
of the key is intended to remind one of a node being “nailed” to the canvas.
Example
a
c
d
b
\tikz \graph [edges=rounded corners, nodes=draw,
layered layout, sibling distance=0] {
a -- {b,c,d[nail at={(1,0)}]} -- e[nail at={(1.5,-1)}] -- a;
};
e
27.7
Packing of Connected Components
Graphs may be composed of subgraphs or components that are not connected to each other. In order to
draw these nicely, most graph drawing algorithms split them into separate graphs, compute their layouts
with the same graph drawing algorithm independently and, in a postprocessing step, arrange them next to
each other. Note, however, that some graph drawing algorithms can also arrange the nodes of the graph in
a uniform way even for unconnected components (the simple necklace layout is a case in point); for such
algorithms you can choose whether they should be applied to each component individually or not (if not,
the following options do not apply). To configure which is the case, use the componentwise key.
The default method for placing the different components works as follows:
1. For each component, a layout is determined and the component is oriented as described Section 27.5
on the orientation of graphs.
2. The components are sorted as prescribed by the component order key.
3. The first component is now placed (conceptually) at the origin. (The final position of this and all other
components will be determined later, namely in the anchoring phase, but let us imagine that the first
component lies at the origin at this point.)
380
4. The second component is now positioned relative to the first component. The “direction” in which
the next component is placed relative to the first one is determined by the component direction
key, so components can be placed from left to right or up to down or in any other direction (even
something like 30◦ ). However, both internally and in the following description, we assume that the
components are placed from left to right; other directions are achieved by doing some (clever) rotating
of the arrangement achieved in this way.
So, we now wish to place the second component to the right of the first component. The component is
first shifted vertically according to some alignment strategy. For instance, it can be shifted so that the
topmost node of the first component and the topmost node of the second component have the same
vertical position. Alternatively, we might require that certain “alignment nodes” in both components
have the same vertical position. There are several other strategies, which can be configured using the
component align key.
One the vertical position has been fixed, the horizontal position is computed. Here, two different
strategies are available: First, image rectangular bounding boxed to be drawn around both components.
Then we shift the second component such that the right border of the bounding box of the first
component touches the left border of the bounding box of the second component. Instead of having
the bounding boxes “touch,” we can also have a padding of component sep between them. The second
strategy is more involved and also known as a “skyline” strategy, where (roughly) the components are
“moved together as near as possible so that nodes do not touch”.
5. After the second component has been placed, the third component is considered and positioned relative
to the second one, and so on.
6. At the end, as hinted at earlier, the whole arrangement is rotate so that instead of “going right” the
component go in the direction of component direction. Note, however, that this rotation applies
only to the “shift” of the components; the components themselves are not rotated. Fortunately, this
whole rotation process happens in the background and the result is normally exactly what you would
expect.
In the following, we go over the different keys that can be used to configure the component packing.
(default true)
/graph drawing/componentwise=hbooleani
For algorithms that also support drawing unconnected graphs, use this key to enforce that the components of the graph are, nevertheless, laid out individually. For algorithms that do not support laying
out unconnected graphs, this option has no effect; rather it works as if this option were always set.
Examples
a
3
b
c
2
1
d
a
b
c
,
27.7.1
,
1
d
\tikz \graph [simple necklace layout]
{
a -- b -- c -- d -- a,
1 -- 2 -- 3 -- 1
};
2
3
\tikz \graph [simple necklace layout, componentwise]
{
a -- b -- c -- d -- a,
1 -- 2 -- 3 -- 1
};
Ordering the Components
The different connected components of the graph are collected in a list. The ordering of the nodes in this
list can be configured using the following key.
(initially by first specified node)
/graph drawing/component order=hstringi
Selects a “strategy” for ordering the components. By default, they are ordered in the way they appear
in the input.
The following values are permissible for hstrategyi
381
• by first specified node
The components are ordered “in the way they appear in the input specification of the graph”. More
precisely, for each component consider the node that is first encountered in the description of the
graph. Order the components in the same way as these nodes appear in the graph description.
• increasing node number
The components are ordered by increasing number of nodes. For components with the same number
of nodes, the first node in each component is considered and they are ordered according to the
sequence in which these nodes appear in the input.
• decreasing node number As above, but in decreasing order.
Examples
a
b
c
f
d
g
\tikz \graph [tree layout, nodes={inner sep=1pt,draw,circle},
component order=by first specified node]
{ a, b, c, f -- g, c -- d -- e };
e
a
b
f
c
g
d
\tikz \graph [tree layout, nodes={inner sep=1pt,draw,circle},
component order=increasing node number]
{ a, b, c -- d -- e, f -- g };
e
/graph drawing/small components first=hstringi
A shorthand for component order=increasing node number.
/graph drawing/large components first=hstringi
A shorthand for component order=decreasing node number.
Example
c
f
d
g
a
b
\tikz \graph [tree layout, nodes={inner sep=1pt,draw,circle},
large components first]
{ a, b, c -- d -- e, f -- g };
e
27.7.2
Arranging Components in a Certain Direction
/graph drawing/component direction=hdirectioni
(initially 0)
The hanglei is used to determine the relative position of each component relative to the previous one.
The direction need not be a multiple of 90. As usual, you can use texts like up or right instead of a
number.
As the examples show, the direction only has an influence on the relative positions of the components,
not on the direction of growth inside the components. In particular, the components are not rotated by
this option in any way. You can use the grow option or orient options to orient individual components.
Examples
f
c
g
d
b
a
\tikz \graph [tree layout, nodes={inner sep=1pt,draw,circle},
component direction=left]
{ a, b, c -- d -- e, f -- g };
e
382
a
f
c
b
g
d
\tikz \graph [tree layout, nodes={inner sep=1pt,draw,circle},
component direction=10]
{ a, b, c -- d -- e, f -- g };
e
g
\tikz \graph [tree layout, nodes={inner sep=1pt,draw,circle},
component direction=up]
{ a, b, c [grow=right] -- d -- e, f[grow=45] -- g };
f
c
e
d
b
a
27.7.3
Aligning Components
When components are placed next to each from left to right, it is not immediately clear how the components
should be aligned vertically. What happens is that in each component a horizontal line is determined and
then all components are shifted vertically so that the lines are aligned. There are different strategies for
choosing these “lines”, see the description of the options described later on. When the component direction
option is used to change the direction in which components are placed, it certainly make no longer sense to
talk about “horizontal” and “vertical” lines. Instead, what actually happens is that the alignment does not
consider “horizontal” lines, but lines that go in the direction specified by component direction and aligns
them by moving components along a line that is perpendicular to the line. For these reasons, let us call the
line in the component direction the alignment line and a line that is perpendicular to it the shift line.
The first way of specifying through which point of a component the alignment line should get is to use
the option align here. In many cases, however, you will not wish to specify an alignment node manually in
each component. Instead, you will use the component align key to specify a strategy that should be used
to automatically determine such a node.
Using a combination of component direction and component align, numerous different packing strategies can be configured. However, since names like counterclockwise are a bit hard to remember and to
apply in practice, a number of easier-to-remember keys are predefined that combine an alignment and a
direction.
(default true)
/graph drawing/align here=hbooleani
When this option is given to a node, this alignment line will go through the origin of this node. If this
option is passed to more than one node of a component, the node encountered first in the component is
used.
Example
b
a
d
c
\tikz \graph [binary tree layout, nodes={draw}]
{ a, b -- c[align here], d -- e[second, align here] -- f };
e
f
(initially first node)
/graph drawing/component align=hstringi
Specifies a “strategy” for the alignment of components.
The following values are permissible:
• first node In each component, the alignment line goes through the center of the first node of the
component encountered during specification of the component.
383
a
b
\tikz \graph [binary tree layout, nodes={draw},
component align=first node]
{ a, b -- c, d -- e[second] -- f };
d
c
e
f
• center
The nodes of the component are projected onto the shift line. The alignment line is now chosen
so that it is exactly in the middle between the maximum and minimum value that the projected
nodes have on the shift line.
\tikz \graph [binary tree layout, nodes={draw},
component align=center]
{ a, b -- c, d -- e[second] -- f };
d
b
a
e
c
f
d
e
\tikz \graph [binary tree layout, nodes={draw},
component direction=90,
component align=center]
{ a, b -- c, d -- e[second] -- f };
f
b
c
a
• counterclockwise
As for center, we project the nodes of the component onto the shift line. The alignment line is
now chosen so that it goes through the center of the node whose center has the highest projected
value.
a
b
\tikz \graph [binary tree layout, nodes={draw},
component align=counterclockwise]
{ a, b -- c, d -- e[second] -- f };
d
c
e
f
d
e
\tikz \graph [binary tree layout, nodes={draw},
component direction=90,
component align=counterclockwise]
{ a, b -- c, d -- e[second] -- f };
f
b
c
a
384
The name counterclockwise is intended to indicate that the align line goes through the node
that comes last if we go from the alignment direction in a counter-clockwise direction.
• clockwise
Works like counterclockwise, only in the other direction:
\tikz \graph [binary tree layout, nodes={draw},
component align=clockwise]
{ a, b -- c, d -- e[second] -- f };
d
e
b
a
c
f
d
e
\tikz \graph [binary tree layout, nodes={draw},
component direction=90,
component align=clockwise]
{ a, b -- c, d -- e[second] -- f };
f
b
c
a
• counterclockwise bounding box
This method is quite similar to counterclockwise, only the alignment line does not go through
the center of the node with a maximum projected value on the shift line, but through the maximum
value of the projected bounding boxes. For a left-to-right packing, this means that the components
are aligned so that the bounding boxes of the components are aligned at the top.
a high
node
a high
node
b
b
\tikz \graph [tree layout, nodes={draw, align=center},
component sep=0pt,
component align=counterclockwise]
{ a, "high\\node" -- b};\quad
\tikz \graph [tree layout, nodes={draw, align=center},
component sep=0pt,
component align=counterclockwise bounding box]
{ a, "high\\node" -- b};
• clockwise bounding box
Works like counterclockwise bounding box.
/graph drawing/components go right top aligned=hstringi
Shorthand for component direction=right and component align=counterclockwise. This means
that, as the name suggest, the components will be placed left-to-right and they are aligned such that
their top nodes are in a line.
Example
a
high
node
\tikz \graph [tree layout, nodes={draw, align=center},
components go right top aligned]
{ a, "high\\node" -- b};
b
/graph drawing/components go right absolute top aligned=hstringi
385
Like components go right top aligned, but with component align set to counterclockwise
bounding box. This means that the components will be aligned with their bounding boxed being
top-aligned.
Example
a
high
node
\tikz \graph [tree layout, nodes={draw, align=center},
components go right absolute top aligned]
{ a, "high\\node" -- b};
b
/graph drawing/components go right bottom aligned=hstringi
See the other components go ... keys.
/graph drawing/components go right absolute bottom aligned=hstringi
See the other components go ... keys.
/graph drawing/components go right center aligned=hstringi
See the other components go ... keys.
/graph drawing/components go right=hstringi
Shorthand for component direction=right and component align=first node.
/graph drawing/components go left top aligned=hstringi
See the other components go ... keys.
Example
high
node
a
\tikz \graph [tree layout, nodes={draw, align=center},
components go left top aligned]
{ a, "high\\node" -- b};
b
/graph drawing/components go left absolute top aligned=hstringi
See the other components go ... keys.
/graph drawing/components go left bottom aligned=hstringi
See the other components go ... keys.
/graph drawing/components go left absolute bottom aligned=hstringi
See the other components go ... keys.
/graph drawing/components go left center aligned=hstringi
See the other components go ... keys.
/graph drawing/components go left=hstringi
See the other components go ... keys.
/graph drawing/components go down right aligned=hstringi
See the other components go ... keys.
Examples
a
\tikz \graph [tree layout, nodes={draw, align=center},
components go down left aligned]
{ a, hello -- {world,s} };
hello
world
s
386
hello
world
s
\tikz \graph [tree layout, nodes={draw, align=center},
components go up absolute left aligned]
{ a, hello -- {world,s}};
a
/graph drawing/components go down absolute right aligned=hstringi
See the other components go ... keys.
/graph drawing/components go down left aligned=hstringi
See the other components go ... keys.
/graph drawing/components go down absolute left aligned=hstringi
See the other components go ... keys.
/graph drawing/components go down center aligned=hstringi
See the other components go ... keys.
/graph drawing/components go down=hstringi
See the other components go ... keys.
/graph drawing/components go up right aligned=hstringi
See the other components go ... keys.
/graph drawing/components go up absolute right aligned=hstringi
See the other components go ... keys.
/graph drawing/components go up left aligned=hstringi
See the other components go ... keys.
/graph drawing/components go up absolute left aligned=hstringi
See the other components go ... keys.
/graph drawing/components go up center aligned=hstringi
See the other components go ... keys.
/graph drawing/components go up=hstringi
See the other components go ... keys.
27.7.4
The Distance Between Components
Once the components of a graph have been oriented, sorted, aligned, and a direction has been chosen, it
remains to determine the distance between adjacent components. Two methods are available for computing
this distance, as specified by the following option:
(initially skyline)
/graph drawing/component packing=hstringi
Given two components, their distance is computed as follows in depencende of hmethod i:
• rectangular
Imagine a bounding box to be drawn around both components. They are then shifted such that the
padding (separating distance) between the two boxes is the current value of component sep.
a
longer text
long text
b
\tikz \graph [tree layout, nodes={draw}, component sep=0pt,
component packing=rectangular]
{ a -- long text, longer text -- b};
387
• skyline
The “skyline method” is used to compute the distance. It works as follows: For simplicity, assume
that the component direction is right (other case work similary, only everything is rotated). Imaging
the second component to be placed far right beyond the first component. Now start moving the
second component back to the left until one of the nodes of the second component touches a node
of the first component, and stop. Again, the padding component sep can be used to avoid the
nodes actually touching each other.
a longer text
long text
\tikz \graph [tree layout, nodes={draw}, component sep=0pt,
level distance=1.5cm,
component packing=skyline]
{ a -- long text, longer text -- b};
b
In order to avoid nodes of the second component “passing through a hole in the first component,”
the actual algorithm is a bit more complicated: For both components, a “skyline” is computed.
For the first component, consider an arbitrary horizontal line. If there are one or more nodes on
this line, the rightmost point on any of the bounding boxes of these nodes will be the point on the
skyline of the first component for this line. Similarly, for the second component, for each horizontal
level the skyline is given by the leftmost point on any of the bounding boxes intersecting the line.
Now, the interesting case are horizontal lines that do not intersect any of the nodes of the first
and/or second component. Such lines represent “holes” in the skyline. For them, the following
rule is used: Move the horizontal line upward and downward as little as possible until a height is
reached where there is a skyline defined. Then the skyline position on the original horizontal line
is the skyline position at the reached line, minus (or, for the second component, plus) the distance
by which the line was moved. This means that the holes are “filled up by slanted roofs.”
a
longer text
long text
27.8
b
\begin{tikzpicture}
\graph [tree layout, nodes={draw}, component sep=0pt,
component packing=skyline]
{ a -- long text, longer text -- b};
\draw[red] (long text.north east) -- ++(north west:1cm);
\end{tikzpicture}
Anchoring Edges
When a graph has been layed out completely, the edges between the nodes must be drawn. Conceptually,
an edge is “between two nodes,” but when we actually draw the node, we do not really want the edge’s path
to start “in the middle” of the node; rather, we want it to start “on the border” and also end there.
Normally, computing such border positions for nodes is something we would leave to the so-called display
layer (which is typically Tik Z and Tik Z is reasonably good at computing border positions). However, different
display layers may behave differently here and even Tik Z fails when the node shapes are very involved and
the paths also.
For these reasons, computing the anchor positions where edges start and end is done inside the graph
drawing system. As a user, you specify a tail anchor and a head anchor, which are points inside the tail
and head nodes, respectively. The edge path will then start and end at these points, however, they will
usually be shortened so that they actually start and end on the intersection of the edge’s path with the
nodes’ paths.
/graph drawing/tail anchor=hstringi
Specifies where in the tail vertex the edge should start.
This is either a string or a number, interpreted as an angle (with 90 meaning “up”). If it is a string,
when the start of the edge is computed, we try to look up the anchor in the tail vertex’s table of anchors
(some anchors get installed in this table by the display system). If it is not found, we test whether it is
one of the special “direction anchors” like north or south east. If so, we convert them into points on
the border of the node that lie in the direction of a line starting at the center to a point on the bounding
box of the node in the designated direction. Finally, if the anchor is a number, we use a point on the
border of the node that is on a line from the center in the specified direction.
388
If the anchor is set to the empty string (which is the default), the anchor is interpreted as the center
anchor inside the graph drawing system. However, a display system may choose to make a difference
between the center anchor and an empty anchor (Tik Z does: for options like bend left if the anchor
is empty, the bend line starts at the border of the node, while for the anchor set explicitly to center it
starts at the center).
Note that graph drawing algorithms need not take the setting of this option into consideration. However,
the final rendering of the edge will always take it into consideration (only, the setting may not be very
sensible if the algorithm ignored it).
/graph drawing/head anchor=hstringi
See tail anchor
(default true, initially true)
/graph drawing/tail cut=hbooleani
Decides whether the tail of an edge is “cut”, meaning that the edge’s path will be shortened at the
beginning so that it starts only of the node’s border rather than at the exact position of the tail anchor,
which may be inside the node.
(default true, initially true)
/graph drawing/head cut=hbooleani
See tail cut.
(initially as edge requests)
/graph drawing/cut policy=hstringi
The policy for cutting edges entering or leaving a node.
This option is important for nodes only. It can have three possible values:
• as edge requests Whether or not an edge entering or leaving the node is cut depends on the
setting of the edge’s tail cut and head cut options. This is the default.
• all All edges entering or leaving the node are cut, regardless of the edges’ cut values.
• none No edge entering or leaving the node is cut, regardless of the edges’ cut values.
(default true, initially true)
/graph drawing/allow inside edges=hbooleani
Decides whether an edge between overlapping nodes should be drawn.
If two vertices overlap, it may happen that when you draw an edge between them, this edges would be
completely inside the two vertices. In this case, one could either not draw them or one could draw a
sort of “inside edge”.
Examples
a
a
27.9
b
b
c
c
\tikz \graph [no layout, nodes={draw, minimum size=20pt}] {
a [x=0, y=0] -- b [x=15pt, y=10pt] -- c[x=40pt]
};
\tikz \graph [no layout, nodes={draw, minimum size=20pt},
allow inside edges=false] {
a [x=0, y=0] -- b [x=15pt, y=10pt] -- c[x=40pt]
};
Hyperedges
(style)
/graph drawing/hyper
A hyperedge of a graph does not connect just two nodes, but is any subset of the node set (although
a normal edge is also a hyperedge that happens to contain just two nodes). Internally, a collection of
kind hyper is created. Currently, there is no default renderer for hyper edges.
389
\graph {
% The nodes:
a, b, c, d;
% The edges:
{[hyper] a,b,c};
{[hyper] b,c,d};
{[hyper] a,c};
{[hyper] d}
};
27.10
Using Several Different Layouts to Draw a Single Graph
Inside each graph drawing scope, a main algorithm is used to perform the graph drawing. However, parts
of the graph may be drawn using different algorithms: For instance, a graph might consist of several, say,
cliques that are arranged in a tree-like fashion. In this case, it might be useful to layout each clique using a
circular layout, but then lay out all laid out cliques using a tree drawing algorithm.
In order to lay out a graph using multiple algorithms, we need two things: First, we must be able to
specify which algorithms should be used where and, second, we must be able to resolve conflicts that may
result from different algorithms “having different ideas” concerning where nodes should be placed.
27.10.1
Sublayouts
Specifying different layouts for a graph is easy: Inside a graph drawing scope, simply open scopes, in which
you use an option like tree layout for the nodes mentioned in this scope. Inside these scopes, you can
open even subscopes for sublayouts, and so on. Furthermore, the graphs library has special support for
sublayouts.
Let us start with the “plain” syntax for opening sublayouts: You pass a key for creating layouts to a
scope:
a
b
c
1
\tikz [spring layout] {
\begin{scope}[tree layout]
\node (a) {a};
\node (b) {b};
\node (c) {c};
\draw (a) edge (b) edge (c);
\end{scope}
2
\begin{scope}[tree layout]
\node (1) {1};
\node (2) {2};
\draw (1) edge (2);
\end{scope}
\draw (a) edge (1);
}
Let us see, what is going on here. The main layout (spring layout) contains two sublayouts (the two
tree layouts). Both of them are laid out independently (more on the details in a moment). Then, from
the main layout’s point of view, the sublayouts behave like “large nodes” and, thus, the edge between a and
1 is actually the only edge that is used by the spring layout – resulting in a simple layout consisting of
one big node at the top and a big node at the bottom.
The graphs library has a special support for sublayouts: The syntax is as follows: wherever a normal
node would go, you can write
// [hlayout optionsi] {hsublayouti}
Following the double slash, you may provide hlayout optionsi in square brackets. However, you must
provide a sublayout in braces. The contents of hsublayouti will be parsed using the usual graph syntax, but
will form a sublayout.
390
a
c
b
1
\tikz \graph [spring layout] {
// [tree layout] { a -- {b, c} };
// [tree layout] { 1 -- 2 };
a -- 1;
};
2
In the above example, there is no node before the double slash, which means that the two sublayouts will
be part of the main graph, but will not be indicated otherwise.
\tikz \graph [simple necklace layout] {
// [simple necklace layout] { a -> b -> c -> d -> e -> f -> a };
a
b
f
1
// [tree layout] { % first tentacle
a -> {1, 2};
};
2
c
e
d
3
// [tree layout] {% second tentacle
d -> {3, 4 -> {5, 6}}
};
};
4
5
6
In the above example, the first sublayout is the one for the nodes with letter names. These nodes are
arranged using a simple necklace layout as the sublayout inherits this option from the main layout. The
two small trees (a -> {1, 2} and the tree starting at the d node) are also sublayouts, triggered by the
tree layout option. They are also arranged. Then, all of the layouts are merged (as described later). The
result is actually a single node, so the main layout does nothing here.
Compare the above to the following code:
\tikz \graph [simple necklace layout] {
// [tree layout] { % first ‘‘giant node’’
a -> {1, 2};
};
a
1
2
f
b
a -> b -> c -> d;
e
c
// [tree layout] {% second ‘‘giant node’’
d -> {3, 4 -> {5, 6}}
},
d
3
4
d -> e -> f -> a;
};
5
6
Here, only the two trees are laid out first. They are then contracted into “giant nodes” and these are
then part of the set of nodes that are arranged by the simple necklace layout. For details of how this
contracting works, see below.
27.10.2
Subgraph Nodes
A subgraph node is a special kind of node that “surrounds” the vertices of a subgraph. The special property
of a subgraph node opposed to a normal node is that it is created only after the subgraph has been laid out.
However, the difference to a collection like hyper is that the node is available immediately as a normal node
in the sense that you can connect edges to it.
The syntax used to declare a subgraph node in a graph specification is as follows:
"hnode namei"/"htexti" [hnode optionsi] // [hlayout optionsi] {hsubgraphi}
The idea ist that a subgraph node is declared like a normal node specification, but is followed by a double
slash and a subgraph:
391
\tikz \graph [simple necklace layout] {
tree 1[draw, circle] // [tree layout] { a -> {1, 2}; }
-> b
-> c
-> tree 2[draw] // [tree layout] { d -> {3, 4 -> {5, 6} } }
-> e
-> f
-> tree 1;
};
tree 1
a
1
2
f
b
c
e
tree 2
d
3
4
5
6
Note how the two subgraph nodes tree 1 and tree 2 surround the two smaller trees. In the example,
both had trees as contents and these trees were rendered using a sublayout. However, a subgraph layout does
not need to have its own layout: If you do not provide a layout name after the double slash, the subgraph
node will simply surround all nodes that were placed by the main layout wherever they were placed:
\tikz [subgraph text bottom=text centered,
subgraph nodes={font=\itshape}]
\graph [tree layout] {
a -> { b -> {c, d}, e -> {f, g -> h} };
a
e
b
c
d
left [draw] // { b, c, d };
right [draw] // { e, f, g, h};
g
f
left
left <-> right;
};
h
right
Every time a subgraph node is created, the following style is execute:
(no value)
/tikz/every subgraph node
Set a subgraph node style.
(no default)
/tikz/subgraph nodes=hstylei
Sets the every subgraph node style to hstylei.
\tikz [subgraph text bottom=text centered,
subgraph nodes=red]
\graph [tree layout] {
a -> { b -> {c, d}, e -> {f, g -> h} };
a
e
b
c
d
left [draw] // { b, c, d };
right [draw] // { e, f, g, h};
g
f
left
left <-> right;
h
};
right
(no value)
/tikz/subgraph text none
When this option is used, the text of a subgraph node is not shown. Adding a slash after the node name
achieves roughly the same effect, but this option is useful in situations when subgraph nodes generally
should not have any text inside them.
392
\tikz [subgraph text none]
\graph [tree layout] {
a -> { b -> {c, d}, e -> {f, g -> h} };
a
e
b
left [draw] // { b, c, d };
right [draw] // { e, f, g, h};
c
d
g
f
left <-> right;
};
h
/tikz/subgraph text top=htext alignment optionsi
(default text ragged right)
Specifies that the text of a subgraph node should be placed at the top of the subgraph node: Still inside
the node, but above all nodes inside the subgraph node.
\tikz [subgraph text top=text ragged left]
\graph [tree layout] {
a -> { b -> {c, d}, e -> {f, g -> h} };
a
left
right
e
b
c
left [draw] // { b, c, d };
right [draw] // { e, f, g, h};
d
g
f
left <-> right;
};
h
You can pass any of the htext alignment optionsi understood by Tik Z, such as text centered:
\tikz [subgraph text top=text centered]
\graph [tree layout] {
a -> { b -> {c, d}, e -> {f, g -> h} };
a
left
e
b
left [draw, circle] // { b, c, d };
};
c
d
f
g
h
To place a label outside the subgraph node, use a label, typically defined using the quotes library:
left
a
b
right
\tikz \graph [tree layout] {
a -> { b -> {c, d}, e -> {f, g -> h} };
e
/ ["left", draw] // { b, c, d } <->
/ ["right", draw] // { e, f, g, h};
};
c
d
f
g
h
/tikz/subgraph text bottom=htext alignment optionsi
(default ragged right)
Works like subgraph text top, only the text placed at the bottom.
Note that there are no keys subgraph text left or ...
right, for somewhat technical reasons.
(no default, initially .1em)
/tikz/subgraph text sep=hdimensioni
Some space added between the inner nodes of a subgraph node and the text labels.
393
27.10.3
Overlapping Sublayouts
Nodes and edges can be part of several layouts. This will inevitably lead to conflicts because algorithm will
disagree on where a node should be placed on the canvas. For this reason, there are some rules governing
how such conflicts are resolved: Given a layout, starting with the main layout, the graph drawing system
does the following:
1. We start by first processing the (direct) sublayouts of the current layout (recursively). Sublayouts
may overlap (they may share one or more nodes), but we run the specified layout algorithm for each
sublayout independently on a “fresh copy” of all the nodes making up the sublayout. In particular,
different, conflicting positions may be computed for nodes when they are present in several sublayouts.
2. Once all nodes in the sublayouts have been laid out in this way, we join overlapping elements. The
idea is that if two layouts share exactly one vertex, we can shift them around so that his vertex is at
the same position in both layouts. In more detail, the following happens:
We build a (conceptual) graph whose nodes are the sublayouts and in which there is an edge between
two nodes if the sublayouts represented by these elements have a node in common. Inside the resulting
graph, we treat each connected component separately. Each component has the property that the
sublayouts represented by the nodes in the component overlap by at least one node. We now join them
as follows: We start with the first sublayout in the component (“first” with respect to the order in
which they appear in the input graph) and “mark” this sublayout. We loop the following instructions
as long as possible: Search for the first sublayout (again, with respect to the order in which they
appear in the input) that is connect by an edge to a marked sublayout. The sublayout will now have
at least one node in common with the marked sublayouts (possibly, even more). We consider the first
such node (again, first respect to the input ordering) and shift the whole sublayout is such a way that
this particular node is at the position is has in the marked sublayouts. Note that after the shift, other
nodes that are also present in the marked sublayouts may lie at a different position in the current
sublayout. In this case, the position in the marked sublayouts “wins.” We then mark the sublayout.
3. When the above algorithm has run, we will have computed positions for all nodes in all sublayouts of
each of the components. For each component, we contract all nodes of the component to a single node.
This new node will be “large” in the sense that its convex hull is the convex hull of all the nodes in the
component. All nodes that used to be part of the component are removed and the new large node is
added (with arcs adjusted appropriately).
4. We now run the layout’s algorithm on the resulting nodes (the remaining original nodes and the
contracted nodes).
5. In a last step, once the graph has been laid out, we expand the nodes that were previously contracted.
For this, the nodes that were deleted earlier get reinserted, but shifted by whatever amount the
contraction node got shifted.
27.11
Miscellaneous Options
(default true)
/graph drawing/nodes behind edges=hbooleani
Specifies, that nodes should be drawn behind the edges
Once a graph drawing algorithm has determined positions for the nodes, they are drawn before the
edges are drawn; after all, it is hard to draw an edge between nodes when their positions are not yet
known. However, we typically want the nodes to be rendered after or rather on top of the edges. For
this reason, the default behaviour is that the nodes at their final positions are collected in a box that
is inserted into the output stream only after the edges have been drawn – which has the effect that the
nodes will be placed “on top” of the edges.
This behaviour can be changed using this option. When the key is invoked, nodes are placed behind the
edges.
Example
394
2
7
1
3
6
4
\tikz \graph [simple necklace layout, nodes={draw,fill=white},
nodes behind edges]
{ subgraph K_n [n=7], 1 [regardless at={(0,-1)}] };
5
/graph drawing/edges behind nodes=hstringi
This is the default placemenet of edges: Behind the nodes.
Example
2
7
1
3
6
4
\tikz \graph [simple necklace layout, nodes={draw,fill=white},
edges behind nodes]
{ subgraph K_n [n=7], 1 [regardless at={(0,-1)}] };
5
/graph drawing/random seed=hnumber i
(initially 42)
To ensure that the same is always shown in the same way when the same algorithm is applied, the
random is seed is reset on each call of the graph drawing engine. To (possibly) get different results on
different runs, change this value.
/graph drawing/variation=hnumber i
An alias for random seed.
/graph drawing/weight=hnumber i
(initially 1)
Sets the “weight” of an edge or a node. For many algorithms, this number tells the algorithm how
“important” the edge or node is. For instance, in a layered layout, an edge with a large weight will
be as short as possible.
Examples
a
c
b
\tikz \graph [layered layout] {
a -- {b,c,d} -- e -- a;
};
d
e
a
b
c
\tikz \graph [layered layout] {
a -- {b,c,d} -- e --[weight=3] a;
};
d
e
(initially 1)
/graph drawing/length=hlengthi
Sets the “length” of an edge. Algorithms may take this value into account when drawing a graph.
Example
395
a
\tikz \graph [phylogenetic tree layout] {
a --[length=2] b --[length=1] {c,d};
a --[length=3] e
};
b
e
d
c
/graph drawing/radius=hnumber i
(initially 0)
The radius of a circular object used in graph drawing.
/graph drawing/no layout=hstringi
This layout does nothing.
396
28
Using Graph Drawing in PGF
by Till Tantau
PGF Library graphdrawing
\usepgflibrary{graphdrawing}
\usepgflibrary[graphdrawing]
% LATEX and plain TEX
% ConTEXt
This package provides the core support for graph drawing inside pgf. It does so by providing pgf
macros for controlling the graph drawing system, but also implements the binding to the graph drawing
system (see Section 38 for details on bindings).
28.1
Overview
Just like everywhere else in pgf, Tik Z is “just a convenient syntax” in the context of graph drawing. The
“hard work” of binding the internal representations of nodes and edges with the graph drawing system written
in Lua is not done by Tik Z, but rather by a set of macros that are part of the basic pgf layer.
The documentation of the pgf part of the graph drawing system that is presented in the following
includes only those macros that other TEX packages could conceivably call in order to use the graph drawing
system without using Tik Z; for instance, for efficiency reasons. (The internal callback functions defined in
the graph drawing library that are part of the binding between pgf and the graph drawing system are not
documented, should not be called, and may change in the future.)
28.2
How Graph Drawing in PGF Works
The core idea behind graph drawing in pgf is that inside special graph drawing scopes whenever pgf creates a
node, we intercept this node creation and do not immediately place the node. Rather, we pass it down to Lua
part of the graph drawing system via calls to appropriate methods of the (Lua) class InterfaceToDisplay.
The effect will be that the nodes are “tucked away” in some internal tables. For edges, we introduce a
special command called \pgfgdedge that tells the graph drawing system that there is an edge between two
tucked-away nodes. Then, at the end of the graph drawing scope, a graph drawing algorithm written in Lua
starts to work on the graph by computing new positions for the nodes. Once the algorithm has finished,
the graph drawing system starts sending back the nodes and edges to pgf via the methods of the class
BindingToPGF. These methods reinsert some code into the TEX output stream that finally places the nodes
at their final positions. Note that graph drawing algorithms are perfectly oblivious to all of this; indeed, the
graph drawing algorithms can even be used independently of TEX.
Let us have a look at a simple example to see what happens when a graph is specified:
Hello
\tikz[tree layout]
\graph {root [as=Hello] -> World[fill=blue!20]};
World
The key tree layout internally calls the key request scope and layout, which in turn calls the macro
\pgfgdbeginscope, which starts a graph drawing scope inside the graph drawing system. Once this macro
has been called, until the next call of \pgfgdendscope, all nodes that are created actually get passed down
to the graph drawing engine. This is implemented on the lowest layer, namely by directly intercepting nodes
freshly created using \pgfnode. In our example, this happens in two places: For the root node and for the
World node. The graph library and Tik Z internally call the \pgfnode macro for these two nodes (after a
large number of internal syntax translations, but the graph drawing system does not care about them).
Note that the node boxes will have been fully created before they are passed down to the graph drawing
engine – only their final position is not yet fixed. It is not possible to modify the size of nodes inside the
graph drawing engine, but you can create new nodes in certain situations.
In contrast, the single edge of the graph that is created by the -> command is not fully created before it is
passed down to the graph drawing system. This would not really make sense since before the final positions
of the nodes are fixed, we cannot even begin to compute the length of this edge, let alone where it should
start or end. For this reason, on the upper Tik Z layer, the normal edge creation that would be caused by
-> via new -> is suppressed. Instead, the command \pgfgdedge is called. Similarly, inside a graph drawing
scope, Tik Z will suppress both the edge and the edge from parent command and cause \pgfgdedge to be
called instead.
397
An overview of what happens is illustrated by the following call graph:
Tik Z layer (TEX)
\graph[...
layout]{
a -> b;
};
pgf layer (TEX)
Display layer (Lua)
\pgfgdbeginscope
beginGraphDrawingScope(...)
\pgfnode
createVertex(...)
\pgfgdedge
createEdge(...)
\pgfgdendscope
runGraphDrawingAlgorithm()
invoke algorithm
endGraphDrawingScope()
\pgfgdcallbackbeginshipout
\pgfgdcallbackrendernode
\pgfgddefaultedgecallback
\pgfgdcallbackendshipout
The above diagram glosses over the fact that the display layer does not actually call any of the macros of
TEX directly, but uses a so called binding (see the class BindingToPGF). However, this will not be important
for the present section since you cannot access the binding directly.
28.2.1
Graph Drawing Scopes
When the graph drawing system is active, some pretty basic things inside pgf change – such as the fact
that nodes are no longer created in the normal manner. For this reason, the graph drawing system must
be switched on and of explicitly through opening and closing a so called graph drawing scope. These scopes
can, in principle, be nested, namely a graph contains a node that contains some text that in turn contains
a subpicture that contains a drawing of a graph. However, this is not the same as subgraphs nodes and
sublayouts, which are all part of the same graph drawing scope. Normally, graph drawing scopes are not
nested.
Graph drawing scopes are created using the following commands:
\pgfgdbeginscope
This macro starts a TEX scope inside which the following things happen:
1. The display layer method beginGraphDrawingScope is called, which created a new graph drawing
scope inside the graph drawing system and places it on top of an internal stack. From now on, all
subsequent interface calls will refer to this scope until \pgfgdendscope is called, which will pop
the scope once more.
2. Inside the TEX scope, nodes are not placed immediately. Rather, \pgfpositionnodelater, see
Section 101.2.3, is used to call InterfaceToDisplay.createVertex for all nodes created inside
the scope. This will cause them to be put inside some internal table.
3. Some additional hcodei is executed, which has been set using the following command:
\pgfgdaddspecificationhook{hcodei}
This command adds the hcodei to the code that is executed whenever a graph drawing scope
starts. For instance, the Tik Z library graphdrawing uses this macro to add some hcodei that
will redirect the edge and edge from parent path commands to \pgfgdedge.
398
4. \pgftransformreset is called.
5. The following TEX-if is set to true:
\ifpgfgdgraphdrawingscopeactive
Will be true inside a graph drawing scope.
The above has a number of consequences for what can happen inside a graph drawing scope:
• Since nodes are not actually created before the end of the scope, you cannot reference these nodes.
Thus, you cannot write
\tikz [spring layout] {
\node (a) {a};
\node (b) {b};
\draw (a) -- (b);
}
The problem is that we cannot connect (a) and (b) via a straight line since these nodes do not
exist at that point (they are available only deeply inside the Lua).
• In order to create edges between nodes inside a graph drawing scope, you need to call the
\pgfgdedge command, described below.
Additionally, when Tik Z is used, the following things also happen:
• If the graphs library has been loaded, the default positioning mechanisms of this library are
switched off, leaving the positioning to the graph drawing engine. Also, when an edge is created
by the graphs library, this is signalled to the graph drawing library. (To be more precise: The
keys new -> and so on are redefined so that they call \pgfgdedge instead of creating an edge.
• The edge path command is modified so that it also calls \pgfgdedge instead of immediately
creating any edges.
• The edge from parent path command is modified so that is also calls \pgfgdedge.
• The keys append after command and prefix after command keys are modified so that they are
executed only via late options when the node has “reached its final parking position”.
Note that inside a graph drawing scope you first have to open a (main) layout scope (using the
\pgfgdbeginlayout command described later on) before you can add nodes and edges to the scope.
\pgfgdendscope
This macro is used to end a graph drawing scope. It must be given on the same TEX grouping level as
the corresponding \pgfgdbeginscope. When the macro is called, it triggers a lot of new calls:
1. The special treatment of newly created boxes is ended. Nodes are once more created normally.
2. The effects of the hcodei that was inserted via the specification hook command also ends (provided
it had no global effects).
3. We call InterfaceToDisplay.runGraphDrawingAlgorithm. This will cause the algorithm(s) for
the graph to be executed (since a graph can have sublayouts, several algorithms may be run). See
Section 28.3 below.
4. Next, we call InterfaceToDisplay.endGraphDrawingScope. This causes all nodes that were
intercepted during the graph drawing scope to be reinserted into the output stream at the positions
that were computed for them. Also, for each edge that was requested via \pgfgdedge, the callback
macro is called (see below).
Inside a graph drawing scope, nodes are automatically passed down to the graph drawing engine, while
for edges a command has to be called explicitly:
\pgfgdedge{hfirst nodei}{hsecond nodei}{hedge directioni}{hedge optionsi}{hedge nodesi}
This command is used to tell the graph drawing engine that there is an edge between hfirst nodei and
hsecond nodei in your graph. The “kind” of connection is indicated by hdirectioni, which may be one of
the following:
• -> indicates a directed edge (also known as an arc) from hfirst nodei to hsecond nodei.
399
• -- indicates an undirected edge between hfirst nodei and hsecond nodei,
• <- indicates a directed edge from hsecond nodei to hfirst nodei, but with the “additional hint” that
this is a “backward” edge. A graph drawing algorithm may or may not take this hint into account.
• <-> indicates a bi-directed edge between hfirst nodei and hsecond nodei.
• -!- indicates that the edge from hfirst nodei to hsecond nodei is “missing”.
Note that in all cases, the syntatic digraph will contain an arc from hfirst nodei to hsecond nodei,
regardless of the value of hdirectioni. The hdirectioni is “just” a “semantic annotation”.
The parameters hedge optionsi and hedge nodesi are a bit more tricky. When an edge between two
vertices of a graph is created via \pgfgdedge, nothing is actually done immediately. After all, without
knowing the final positions of the nodes hfirst nodei and hsecond nodei, there is no way of creating the
actual drawing commands for the edge. Thus, the actual drawing of the edge is done only when the
graph drawing algorithm is done (namely in the macro \pgfgdedgecallback, see later).
Because of this “delayed” drawing of edges, options that influence the edge must be retained until
the moment when the edge is actually drawn. Parameters hedge optionsi and hedge nodesi store such
options.
Let us start with hedge optionsi. This parameter should be set to a list of key-value pairs like
/tikz/.cd, color=red, very thick, orient=down
Some of these options may be of interest to the graph drawing algorithm (like the last option) while
others will only be important during the drawing of edge (like the first option). The options that are
important for the graph drawing algorithm must be pushed onto the graph drawing system’s option
stack.
The tricky part is that options that are of interest to the graph drawing algorithm must be executed
before the algorithm starts, but the options as a whole are usually only executed during the drawing of
the edges, which is after the algorithm has finished. To overcome this problem, the following happens:
The options in hedge optionsi are executed “tentatively” inside \pgfgdedge. However, this execution is
done in a “heavily guarded sandbox” where all effects of the options (like changing the color or the line
width) do not propagate beyond the sandbox. Only the changes of the graph drawing edge parameters
leave the sandbox. These parameters are then passed down to the graph drawing system.
Later, when the edge is drawn using \pgfgdedgecallback, the options hedge optionsi are available once
more and then they are executed normally.
Note that when the options in hedge optionsi are executed, no path is preset. Thus, you typically need
to start it with, say, /tikz/.cd. Also note that the sandbox is not perfect and changing global values
will have an effect outside the sandbox. Indeed, “putting things in a sandbox” just means that the
options are executed inside a TEX scope inside an interrupted path inside a TEX box that is thrown
away immediately.
The text in hedge nodesi is some “auxilliary” text that is simply stored away and later directed to
\pgfgdedgecallback. This is used for instance by Tik Z to store its node labels.
\pgfgdsetedgecallback{hmacroi}
This command allows you to change the hmacroi that gets called form inside the graph drawing system
at the end of the creation of a graph, when the nodes have been positioned. The hmacroi will be called
once for each edge with the following parameters:
hmacroi{hfirst nodei}{hsecond nodei}{hdirectioni}{hedge optionsi}{hedge nodesi}
{halgorithm-generated optionsi}{hbend informationi}
The first five parameters are the original values that were passed down to the \pgfgdedge command.
The halgorithm-generated optionsi have been “computed by the algorithm”. For instance, an algorithm
might have determined, say, flow capacities for edges and it might now wish to communicate this
information back to the upper layers. These options should be executed with the path /graph drawing.
The parameter hbend informationi contains algorithmically-computed information concerning how the
edge should bend. This will be a text like (10pt,20pt)--(30pt,40pt) in Tik Z-syntax and may include
the path commands --, .. (followed by Bézier coordintes), and --cycle.
400
The default hmacroi simply draws a line between the nodes. When the graphdrawing library of the
Tik Z layer is loaded, a more fancy hmacroi is used that takes all of the parameters into account.
28.3
Layout Scopes
As described in Section 27.10, the graph drawing engine does not always apply only a single algorithm.
Rather, several different algorithm may be applied to different parts of the graph. How this happens,
exactly, is goverened by a hierarchy of layouts, which are setup using the commands \pgfgdbeginlayout
and \pgfgdendlayout.
\pgfgdbeginlayout
This command first starts a new TEX scope and then informs the display layer that a new (sub)layout
should be started. For each graph there may be a hierarchy of layouts, each of which contains a
certain number of vertices and edges. This hierarchy is created through calls to this macros and the
corresponding calls of \pgfgdendlayout. For each graph drawing scope there has to be exactly one
main layout that encompasses all nodes and edges and also all sublayouts. Thus, after a graph drawing
scope has been opened, a layout scope also needs to be opened almost immediately.
For each layout created via this macro, a graph drawing algorithm will be run later on on the subgraph
of all nodes that make up the layout. Which algorithm is run for the layout is dictated by which layout
key (one of the ... layout keys) is “in force” when the macro is called. Thus, using a layout key for
selecting an algorithm must always be done before the layout is started. (However, see the discussion
of layout keys in the next subsection for more details on what really happens.)
A vertex can be part of several layouts, either because they are nested or because they overlap (this
happens when a node is later on added to another layout by calling \pgfgdsetlatenodeoption). This
means that it is not immediately obvious how conflicts arising from the different ways different algorithms “would like to place nodes” should be resolved. The method for this resolving is detailed in
Section 27.10.3.
\pgfgdendlayout
This command ends the TEX scope of the current layout. Once closed, no nodes or edges can be added
to a layout.
\pgfgdsetlatenodeoption{hnode namei}
This command can only be called when the node named hnode namei has already been created inside
the current graph drawing scope. The effect of calling this macro will be that all options currently on
the graph drawing system’s option stack will be added to the node’s option, possibly overwriting the
original option settings. Furthermore, the node will become part of all layouts currently on the option
stack. This means that you can use this command to add a node to several layouts that are not included
in one another.
28.4
Layout Keys
Layout keys are keys like tree layout or layered layout that are used to select a specific graph drawing
algorithm. From the graph drawing system’s point of view, these keys “just” select an algorithm and when
several layout keys are used in a row, the last one would “win”; just as when you say orient=90 directly
followed by orient=0, the result is that the orient key is set to 0 because the last key “wins.”
Unfortunately, if keys like tree layout were “just” to select an algorithm, we would still need a key or
some special syntax to actually start a (sub)layout. In early versions of the system this was exactly what
people had to do and this was somewhat awkward. Because of this problem, the behaviour of the layout
keys in pgf (and only there, other display layers need to implement their own behaviour) is now a bit more
involved. When you use a key like tree layout (more precisely, any key that was declared as an algorithm
key on the algorithm layer of the graph drawing system) in any scope in pgf, the following happens:
1. The graph drawing system is told that a specific algorithm has been selected (the Reingold–Tilfordalgorithm in this case; this information was communicated to the graph drawing system during the
declaration of the algorithm). Being “told” about this means that a special entry is pushed onto the
current options stack of the graph drawing system.
2. An internal “request” for a “scope and a layout” is made. This has several effects:
401
3. We first test whether we are already inside a layout scope. If not, we use \pgfgdbeginscope to open
a graph drawing scope. This scope will be closed appropriately (see \pgfgdsetrequestcallback for
details).
4. Next, a layout scope is opened using \pgfgdbeginlayout. It will also be closed appropriately.
The net effect of the above is that the first use of a layout key in a picture starts both a graph drawing
scope and also a main layout, while subsequent uses of layout keys inside a picture will only open sublayouts.
\pgfgdsetrequestcallback{hmacroi}
This command sets up hmacroi as the macro that is called whenever a layout key “requests” that a
layout and, possibly, a graph drawing scope is opened. When hmacroi is called, it gets two parameters,
the hbegin codei and the hend codei. In addition to whatever setup the hmacroi would like to do, it
should execute the hbegin codei at the beginning of a TEX scope (the code will open graph drawing and
layout scopes) and the hend codei at the end of the same TEX scope.
The need for this slightly strange macro arises from the fact that in Tik Z we often write things like
[spring layout,node sep=2cm]. The point is that when the spring layout key is executed, we do
not wish to open a layout scope immediately. Rather, this should happen only after the option nodes
sep=2cm has been executed. For this reason, Tik Z sets up a special hmacroi that “delays” the execution
of the hbegin codei until the end of the opening of the next scope.
Because of this, in Tik Z layout keys can only be used as an option when a Tik Z scope is started. Thus,
you can pass them to \tikz, to {tikzpicture}, to \scoped, to {scope}, to graph, and to {graph}.
For instance, the tree layout option can be used in the following ways:
1
b
2
c b
3
c b
4
c b
5
c b
6
c b
\tikz [tree layout] \graph
\tikz \graph [tree layout]
\tikz \path graph [tree layout]
{1 -> {b,c}};
{2 -> {b,c}};
{3 -> {b,c}};
\begin{tikzpicture}[tree layout]
\graph
\end{tikzpicture}
{4 -> {b,c}};
\begin{tikzpicture}
\scoped [tree layout] \graph
c
{5 -> {b,c}};
\begin{scope}[tree layout, xshift=1.5cm]
\graph
{6 -> {b,c}};
\end{scope}
\end{tikzpicture}
You can not use layout keys with a single node or on a path. In particular, to typeset a tree given in the
child syntax somewhere inside a {tikzpicture}, you must prefix it with the \scoped command:
root
left child
right child
\begin{tikzpicture}
\scoped [tree layout]
\node {root}
child { node {left child} }
child { node {right child} };
\end{tikzpicture}
Naturally, the above could have been written more succinctly as
root
left child
right child
\tikz [tree layout]
\node {root}
child { node {left child} }
child { node {right child} };
Or even more succinctly:
402
root
left child
28.5
\tikz \graph [tree layout] { root -- {left child, right child} };
right child
Parameters
When a graph drawing algorithm starts working, a set of options, called “graph drawing parameters” or just
“parameters” can influence the way the algorithm works. For instance, a graph drawing parameter might
be the average distance between vertices which the algorithm should take into account. Another example
might be the fact the certain nodes are special nodes and that a certain edge should have a large label.
These graph drawing parameters are different from “usual” pgf options: An alogrithmic parameter
influences the way the algorithm works, while usual options influence the way the result looks like. For
instance, the fact that a node is red is not a graph drawing parameter, while the shape of a node might be
an graph drawing parameter.
The possible graph parameters are declared by the algorithmic layer through the declare method; you
cannot declare parameters on the pgf layer since this would not be compatible across different display
systems.
Users use a graph parameter in the same way as a normal key. The difference is that each time a key
representing a graph drawing parameter is used, a special function of the graph drawing system’s interface
is called to “push” the parameter onto an internal option stack (and elements are popped from this stack
whenever the TEX scope closes in which the key was used).
The net effect of all of this is that the graph drawing system keeps track of a stack of option in parallel
to TEX. You cannot, however, access the current values of graph drawing parameters from TEX since they
are tucked away deep inside the graph drawing system.
28.6
Events
Events are used to pass information from the parser about the syntactic structure of a graph to graph
drawing algorithms. Consider, for instance, a graph that is actually a tree in which some node “misses” its
first child. In this case, the information that the child is missing is neither part of any node (because the
node is missing, after all) nor is it an option of the whole graph. However, events are created by the parser
the allow an algorithm to reconstruct the fact that the child is missing. Naturally, graph drawing algorithms
may choose to ignore events and most will.
Most of the creation and handling of events is done automatically. The only reason you might wish
to use the following commands is when you write a “parser extension” together with a new graph drawing
algorithm. For instance, you might come up with new options that, when used, trigger events.
\pgfgdevent{hkind i}{hparameter i}
Calls createEvent of the graph drawing system’s interface class. This creates a new Event object on
the Lua layer whose kind field is set to hkind i and the parameters field to hparameter i. You must be
inside a graph drawing scope to use this command.
\pgfgdbegineventgroup{hparameter i}
Starts an event group.
hparameter i.
This just means that an Event of kind begin is created with the given
\pgfgdendeventgroup
Ends an event group. This is done by adding an event of kind end without any parameters to the event
string.
\pgfgdeventgroup{hparametersi}
Starts an event group just like \pgfgdbegineventgroup, but adds a corresponding closing end event at
the end of the current TEX group (using \aftergroup).
403
28.7
Subgraph Nodes
\pgfgdsubgraphnode{hnamei}{hnode optionsi}{hnode texti}
A subgraph node is a node that “surrounds” the nodes of a subgraph. The special property of a subgraph
node opposed to a normal node is that it is created only after the subgraph has been laid out. However,
the difference to a collection like hyper is that the node is availble immediately as a normal node in the
sense that you can connect edges to it.
What happens internally is that subgraph nodes get “registered” immediately both on the pgf level and
on the Lua level, but the actual node is only created inside the layout pipeline using a callback. The
actual node creation happens when the innermost layout in which the subgraph node is declared has
finished.
When you create a subgraph node using this macro, you also start a collection (of an internal kind) that
stores the subgraph. All following nodes in the current TEX scope will become part of this collection.
The hnamei is the node name by which you can refer to this node in the following. The hnode optionsi
are normal pgf options (like red or draw or circle) that will influence the appearance when it is
created later on. The hnode texti is the text that will be passed to \pgfnode upon creation of the node.
See InterfaceToDisplay.pushSubgraphVertex for more details.
404
29
Graph Drawing Layouts: Trees
by Till Tantau
Graph Drawing Library trees
\usegdlibrary{trees} % LATEX and plain TEX
\usegdlibrary[trees] % ConTEXt
Tik Z offers several different syntax to specify trees (see Sections 19 and 21). The job of the graph
drawing algorithms from this library is to turn the specification of trees into beautiful layouts.
We start this section with a description of algorithms, then we have a look at how missing children can
be specified and at what happens when the input graph is not a tree.
29.1
The Tree Layouts
29.1.1
The Reingold–Tilford Layout
/graph drawing/tree layout=hstringi
This layout uses the Reingold–Tilform method for drawing trees. The Reingold–Tilford method is a
standard method for drawing trees. It is described in:
• E. M. Reingold and J. S. Tilford, Tidier drawings of trees, IEEE Transactions on Software
Engineering, 7(2), 223–228, 1981.
My implementation in graphdrawing.trees follows the following paper, which introduces some nice
extensions of the basic algorithm:
• A. Brüggemann-Klein, D. Wood, Drawing trees nicely with TEX, Electronic Publishing, 2(2),
101–115, 1989.
As a historical remark, Brüggemann-Klein and Wood have implemented their version of the Reingold–
Tilford algorithm directly in TEX (resulting in the TreeTEX style). With the power of LuaTEX at our
disposal, the 2012 implementation in the graphdrawing.tree library is somewhat more powerful and
cleaner, but it really was an impressive achievement to implement this algorithm back in 1989 directly
in TEX.
The basic idea of the Reingold–Tilford algorithm is to use the following rules to position the nodes of
a tree (the following description assumes that the tree grows downwards, other growth directions are
handled by the automatic orientation mechanisms of the graph drawing library):
1. For a node, recursively compute a layout for each of its children.
2. Place the tree rooted at the first child somewhere on the page.
3. Place the tree rooted at the second child to the right of the first one as near as possible so that no
two nodes touch (and such that the sibling sep padding is not violated).
4. Repeat for all subsequent children.
5. Then place the root above the child trees at the middle position, that is, at the half-way point
between the left-most and the right-most child of the node.
The standard keys level distance, level sep, sibling distance, and sibling sep, as well as the
pre and post versions of these keys, as taken into consideration when nodes are positioned. See also
Section 27.3 for details on these keys.
Handling of Missing Children. As described in Section 29.2, you can specify that some child nodes
are “missing” in the tree, but some space should be reserved for them. This is exactly what happens:
When the subtrees of the children of a node are arranged, each position with a missing child is treated
as if a zero-width, zero-height subtree were present at that positions:
r
a
b
\tikz [tree layout, nodes={draw,circle}]
\node {r}
child { node {a}
child [missing]
child { node {b} }
}
child[missing];
405
or in graph syntax:
\tikz \graph [tree layout, nodes={draw,circle}]
{
r -> {
a -> {
, %missing
b},
% missing
}
};
r
a
b
More than one child can go missing:
r
a
e
b
c
d
\tikz \graph [tree layout, nodes={draw,circle}, sibling sep=0pt]
{ r -> { a, , ,b -> {c,d}, ,e} };
Although missing children are taken into consideration for the computation of the placement of the
children of a root node relative to one another and also for the computation of the position of the root
node, they are usually not considered as part of the “outline” of a subtree (the minimum number of
children key ensures that b, c, e, and f all have a missing right child):
\tikz \graph [tree layout, minimum number of children=2,
nodes={draw,circle}]
{ a -> { b -> c -> d, e -> f -> g } };
a
e
b
c
d
f
g
This behaviour of “ignoring” missing children in later stages of the recursion can be changed using the
key missing nodes get space.
Significant Pairs of Siblings. Brüggemann-Klein and Wood have proposed an extension of the
Reingold–Tilford method that is intended to better highlight the overall structure of a tree. Consider
the following two trees:
\tikz [baseline=(a.base), tree layout, minimum number of children=2,
sibling distance=5mm, level distance=5mm]
\graph [nodes={circle, inner sep=0pt, minimum size=2mm, fill, as=}]{
a -- { b -- c -- { d -- e, f -- { g, h }}, i -- j -- k[second] }
};\quad
\tikz [baseline=(a.base), tree layout, minimum number of children=2,
sibling distance=5mm, level distance=5mm]
\graph [nodes={circle, inner sep=0pt, minimum size=2mm, fill, as=}]{
a -- { b -- c -- d -- e, i -- j -- { f -- {g,h}, k } }
};
As observed by Brüggemann-Klein and Wood, the two trees are structurally quite different, but the
Reingold–Tilford method places the nodes at exactly the same positions and only one edge “switches”
positions. In order to better highlight the differences between the trees, they propose to add a little extra
separation between siblings that form a significant pair. They define such a pair as follows: Consider
the subtrees of two adjacent siblings. There will be one or more levels where these subtrees have a
minimum distance. For instance, the following two trees the subtrees of the nodes a and b have a
minimum distance only at the top level in the left example, and in all levels in the second example. A
significant pair is a pair of siblings where the minimum distance is encountered on any level other than
406
the first level. Thus, in the first example there is no significant pair, while in the second example a and
b form such a pair.
a
a
b
b
\tikz \graph [tree layout, minimum number of children=2,
level distance=5mm, nodes={circle,draw}]
{ / -> { a -> / -> /, b -> /[second] -> /[second] }};
\quad
\tikz \graph [tree layout, minimum number of children=2,
level distance=5mm, nodes={circle,draw}]
{ / -> { a -> / -> /, b -> / -> / }};
Whenever the algorithm encounters a significant pair, it adds extra space between the siblings as specified
by the significant sep key.
Examples
\tikz [tree layout, sibling distance=8mm]
\graph [nodes={circle, draw, inner sep=1.5pt}]{
1 -- { 2 -- 3 -- { 4 -- 5, 6 -- { 7, 8, 9 }}, 10 -- 11 -- { 12, 13 } }
};
1
2
10
3
11
4
5
7
6
12
8
9
13
10
11
1
13
12
2
9
6
3
\tikz [tree layout, grow=-30,
sibling distance=0mm, level distance=0mm]
\graph [nodes={circle, draw, inner sep=1.5pt}]{
1 -- { 2 -- 3 -- { 4 -- 5, 6 -- { 7, 8, 9 }}, 10 -- 11 -- { 12, 13 } }
};
8
7
4
5
/graph drawing/missing nodes get space=hbooleani
(default true)
When set to true, missing children are treated as if they where zero-width, zero-height nodes during the
whole tree layout process.
Example
\tikz \graph [tree layout, missing nodes get space,
minimum number of children=2, nodes={draw,circle}]
{ a -> { b -> c -> d, e -> f -> g } };
a
e
b
c
d
f
g
407
(initially 0)
/graph drawing/significant sep=hlengthi
This space is added to signifcant pairs by the modified Reingold–Tilford algorithm.
Example
\tikz [baseline=(a.base), tree layout, significant sep=1em,
minimum number of children=2,
sibling distance=5mm, level distance=5mm]
\graph [nodes={circle, inner sep=0pt, minimum size=2mm, fill, as=}]{
a -- { b -- c -- { d -- e, f -- { g, h }}, i -- j -- k[second] }
};\quad
\tikz [baseline=(a.base), tree layout, significant sep=1em,
minimum number of children=2,
sibling distance=5mm, level distance=5mm]
\graph [nodes={circle, inner sep=0pt, minimum size=2mm, fill, as=}]{
a -- { b -- c -- d -- e, i -- j -- { f -- {g,h}, k } }
};
/graph drawing/binary tree layout=hstringi
A layout based on the Reingold–Tilford method for drawing binary trees. This key executes:
1. tree layout, thereby selecting the Reingold–Tilford method,
2. minimum number of children=2, thereby ensuring the all nodes have (at least) two children or
none at all, and
3. significant sep=10pt to highlight significant pairs.
In the examples, the last one is taken from the paper of Brüggemann-Klein and Wood. It demonstrates
nicely the advantages of having the full power of Tik Z’s anchoring and the graph drawing engine’s
orientation mechanisms at one’s disposal.
Examples
g
e
h
d
f
k
c
\tikz [grow’=up, binary tree layout, sibling distance=7mm, level distance=7mm]
\graph {
a -- { b -- c -- { d -- e, f -- { g, h }}, i -- j -- k[second] }
};
j
i
b
a
Knuth
Beeton
Beeton
Tobin
Kellermann
Plass
Carnes
Kellermann
Knuth
Lamport
Plass
Carnes
Lamport
Tobin
Spivak
408
Spivak
\tikz \graph [binary tree layout] {
Knuth -> {
Beeton -> Kellermann [second] -> Carnes,
Tobin -> Plass -> { Lamport, Spivak }
}
};\qquad
\tikz [>=spaced stealth’]
\graph [binary tree layout, grow’=right, level sep=1.5em,
nodes={right, fill=blue!50, text=white, chamfered rectangle},
edges={decorate,decoration={snake, post length=5pt}}]
{
Knuth -> {
Beeton -> Kellermann [second] -> Carnes,
Tobin -> Plass -> { Lamport, Spivak }
}
};
/graph drawing/extended binary tree layout=hstringi
This algorithm is similar to binary tree layout, only the option missing nodes get space is executed and the significant sep is zero.
Example
g
e
d
h
f
k
c
j
\tikz [grow’=up, extended binary tree layout,
sibling distance=7mm, level distance=7mm]
\graph {
a -- { b -- c -- { d -- e, f -- { g, h }}, i -- j -- k[second] }
};
i
b
a
29.2
Specifying Missing Children
In the present section we discuss keys for specifying missing children in a tree. For many certain kind of
trees, in particular for binary trees, there are not just “a certain number of children” at each node, but,
rather, there is a designated “first” (or “left”) child and a “second” (or “right”) child. Even if one of these
children is missing and a node actually has only one child, the single child will still be a “first” or “second”
child and this information should be taken into consideration when drawing a tree.
The first useful key for specifying missing children is missing number of children which allows you to
state how many children there are, at minimum.
Once the minimum number of children has been set, we still need a way of specifying “missing first
children” or, more generally, missing children that are not “at the end” of the list of children. For this, there
are three methods:
1. When you use the child syntax, you can use the missing key with the child command to indicate a
missing child:
a
b
c
d
e
f
g
\tikz [binary tree layout, level distance=5mm]
\node {a}
child { node {b}
child { node {c}
child { node {d} }
} }
child { node {e}
child [missing]
child { node {f}
child [missing]
child { node {g}
} } };
409
2. When using the graph syntax, you can use an “empty node”, which really must be completely empty
and may not even contain a slash, to indicate a missing node:
\tikz [binary tree layout, level distance=5mm]
\graph { a -> { b -> c -> d, e -> { , f -> { , g} } } };
a
e
b
c
f
g
d
3. You can simply specify the index of a child directly using the key desired child index.
/graph drawing/minimum number of children=hnumber i
(initially 0)
Specifies how many children a tree node must have at least. If there are less, “virtual” children are
added.
When this key is set to 2 or more, the following happens: We first compute a spanning tree for the
graph, see Section 29.3. Then, whenever a node is not a leaf in this spanning tree (when it has at least
one child), we add “virtual” or “dummy” nodes as children of the node until the total number of real
and dummy children is at least hnumber i. If there where at least hnumber i children at the beginning,
nothing happens.
The new children are added after the existing children. This means that, for instance, in a tree with
hnumber i set to 2, for every node with a single child, this child will be the first child and the second
child will be missing.
Example
a
e
b
c
d
\tikz \graph [binary tree layout,level distance=5mm]
{ a -> { b->c->d, e->f->g } };
f
g
/graph drawing/desired child index=hnumber i
Pass this key to a node to tell the graph drawing engine which child number you “desired” for the node.
Whenever all desires for the children of a node are conflict-free, they will all be met; children for which
no desired indices were given will remain at their position, whenever possible, but will “make way” for
children with a desired position.
In detail, the following happens: We first determine the total number of children (real or dummy)
needed, which is the maximum of the actual number of children, of the minimum number of children,
and of the highest desired child index. Then we go over all children that have a desired child index
and put they at this position. If the position is already taken (because some other child had the same
desired index), the next free position is used with a wrap-around occurring at the end. Next, all children
without a desired index are place using the same mechanism, but they want to be placed at the position
they had in the original spanning tree.
While all of this might sound a bit complicated, the application of the key in a binary tree is pretty
straightforward: To indicate that a node is a “right” child in a tree, just add desired child index=2
to it. This will make it a second child, possibly causing the fist child to be missing. If there are two
nodes specified as children of a node, by saying desired child index=hnumber i for one of them, you
will cause it be first or second child, depending on hnumber i, and cause the other child to become the
other child.
Since desired child index=2 is a bit long, the following shortcuts are available: first, second,
third, and fourth. You might wonder why second is used rather than right. The reason is that trees
may also grow left and right and, additionally, the right and left keys are already in use for anchoring.
Naturally, you can locally redefine them, if you want.
Examples
410
a
b
\tikz \graph [binary tree layout, level distance=5mm]
{ a -> b[second] };
b
\tikz \graph [binary tree layout, level distance=5mm]
{ a -> { b[second], c} };
b
\tikz \graph [binary tree layout, level distance=5mm]
{ a -> { b, c[first]} };
b
\tikz \graph [binary tree layout, level distance=5mm]
{ a -> { b[second], c[second]} };
b
\tikz \graph [binary tree layout, level distance=5mm]
{ a -> { b[third], c[first], d} };
a
c
a
c
a
c
a
c
d
/graph drawing/first=hstringi
A shorthand for setting the desired child number to 1.
/graph drawing/second=hstringi
A shorthand for setting the desired child number to 2.
/graph drawing/third=hstringi
A shorthand for setting the desired child number to 3.
/graph drawing/fourth=hstringi
A shorthand for setting the desired child number to 4.
29.3
Spanning Tree Computation
Although the algorithms of this library are tailored to layout trees, they will work for any graph as input.
First, if the graph is not connected, it is decomposed into connected components and these are laid out
individiually. Second, for each component, a spanning tree of the graph is computed first and the layout
is computed for this spanning tree; all other edges will still be drawn, but they have no impact on the
placement of the nodes. If the graph is already a tree, the spanning tree will be the original graph.
The computation of the spanning tree is a non-trivial process since a non-tree graph has many different
possible spanning trees. You can choose between different methods for deciding on a spanning tree, it is
even possible to implement new algorithms. (In the future, the computation of spanning trees and the cylce
removal in layered graph drawing algorithms will be unified, but, currently, they are implemented differently.)
Selects the (sub)algorithm that is to be used for computing spanning trees whenever this is requested by
a tree layout algorithm. The default algorithm is breadth first spanning tree.
1
2
3
4
5
\tikz \graph [tree layout, breadth first spanning tree]
{
1 -- {2,3,4,5} -- 6;
};
6
411
\tikz \graph [tree layout, depth first spanning tree]
{
1 --[bend right] {2,3,4,5 [>bend left]} -- 6;
};
1
5
6
2
3
4
/graph drawing/breadth first spanning tree=hstringi
This key selects “breadth first” as the (sub)algorithm for computing spanning trees. Note that this key
does not cause a graph drawing scope to start; the key only has an effect in conjunction with keys like
tree layout.
The algorithm will be called whenever a graph drawing algorithm needs a spanning tree on which to
operate. It works as follows:
1. It looks for a node for which the root parameter is set. If there are several such nodes, the first
one is used. If there are no such nodes, the first node is used.
Let call the node determined in this way the root node.
2. For every edge, a priority is determined, which is a number between 1 and 10. How this happens,
exactly, will be explained in a moment. Priority 1 means “most important” while priority 10 means
“least important”.
3. Starting from the root node, we now perform a breadth first search through the tree, thereby
implicitly building a spanning tree: Suppose for a moment that all edges have priority 1. Then,
the algorithm works just the way that a normal breadth first search is performed: We keep a queue
of to-be-visited nodes and while this queue is not empty, we remove its first node. If this node has
not yet been visited, we add all its neighbors at the end of the queue. When a node is taken out
of the queue, we make it the child of the node whose neighbor it was when it was added. Since the
queue follows the “first in, first out” principle (it is a fifo queue), the children of the root will be
all nodes at distance 1 form the root, their children will be all nodes at distance 2, and so on.
4. Now suppose that some edges have a priority different from 1, in which case things get more
complicated. We now keep track of one fifo queue for each of the ten possible priorities. When we
consider the neighbors of a node, we actually consider all its incident edges. Each of these edges
has a certain priority and the neighbor is put into the queue of the edge’s priority. Now, we still
remove nodes normally from the queue for priority 1; only if this queue is empty and there is still
a node in the queue for priority 2 we remove the first element from this queue (and proceed as
before). If the second queue is also empty, we try the third, and so on up to the tenth queue. If
all queues are empty, the algorithm stops.
The effect of the ten queues is the following: If the edges of priority 1 span the whole graph, a spanning
tree consisting solely of these edges will be computed. However, if they do not, once we have visited
reachable using only priority 1 edges, we will extend the spanning tree using a priority 2 edge; but then
we once switch back to using only priority 1 edges. If neither priority 1 nor priority 2 edges suffice to
cover the whole graph, priority 3 edges are used, and so on.
/graph drawing/depth first spanning tree=hstringi
Works exactly like breadth first spanning tree (same handling of priorities), only the queues are
now lifo instead of fifo.
(default true)
/graph drawing/root=hbooleani
This Boolean parameter is used in the computation of spanning trees. When can be set for a node, this
node will be used as the root for the spanning tree computation. If several nodes have this option set,
the first node will be used.
/graph drawing/span priority=hnumber i
Explicitly sets the “span priority” of an edge to hnumber i, which must be a number between 1 and 10.
The priority of edges is used by spanning tree computations, see breadth first spanning tree.
412
/graph drawing/span edge=hstringi
An easy-to-remember shorthand for span priority=1. When this key is used with an edge, it will
always be preferred over other edges
/graph drawing/no span edge=hstringi
An easy-to-remember shorthand for span priority=10. This causes the edge to be used only as a last
resort as part of a spanning tree.
In the example, we add lots of edges that would normally be preferred in the computation of the spanning
tree, but use no span edge to cause the algorithm to ignore these edges.
Example
5
1,3
0
2
11
4
7,9
6
8
10
\tikz \graph [tree layout, nodes={draw}, sibling distance=0pt,
every group/.style={
default edge kind=->, no span edge,
path=source}]
{
5 -> {
"1,3" -> {0,2,4},
11
-> {
"7,9" -> { 6, 8, 10 }
}
}
};
/graph drawing/span priority ->=hnumber i
(initially 3)
This key stores the span priority of all edges whose direction is ->. There are similar keys for all other
directions, such as span priority <- and so on.
When you write
graph { a -> b -- c <- [span priority=2] d }
the priority of the edge from a to b would be the current value of the key span priority ->, the
priority of the edge from b to c would be the current value of span priority --, and the priority of
the edge from c to d would be 2, regardless of the value of span priority <-.
The defaults for the priorities are:
• span priority ->
= 3
• span priority --= 5
• span priority <-> = 5
• span priority <-
= 8
• span priority -!- = 10
/graph drawing/span priority reversed ->=hnumber i
(initially 9)
When you write
graph { a -> b -- c <- [span priority=2] d }
there are, in addition to the priorities indicated above, also further edge priorities: The priority of the
(reversed) edge b to a is span priority reversed ->, the priority of the (reversed) edge c to b is span
priority reversed --, and the span priority of the reversed edge d to c is 2, regardless of the value
of span priority reversed <-.
The defaults for the priorities are:
• span priority reversed ->
= 9
• span priority reversed --= 5
• span priority reversed <-> = 5
• span priority reversed <-
= 7
413
• span priority reversed -!- = 10
The default priorities are set in such a way, that non-reversed -> edges have top priorities, -- and <->
edges have the same priorities in either direction, and <- edges have low priority in either direction (but
going a <- b from b to a is given higher priority than going from a to b via this edge and also higher
priority than going from b to a in a -> b).
Keys like span using directed change the priorities “en bloc”.
/graph drawing/span using directed=hstringi
This style sets a priority of 3 for all edges that are directed and “go along the arrow direction”, that
is, we go from a to b with a priority of 3 for the cases a -> b, b <- a, a <-> b, and b <-> a. This
strategy is nice with trees specified with both forward and backward edges.
Example
5
3
1
8
4
7
9
\tikz \graph [tree layout, nodes={draw}, sibling distance=0pt,
span using directed]
{
3 <- 5[root] -> 8,
1 <- 3 -> 4,
7 <- 8 -> 9,
1 -- 4 -- 7 -- 9
};
/graph drawing/span using all=hstringi
Assings a uniform priority of 5 to all edges.
414
30
Graph Drawing Algorithms: Layered Layouts
by Till Tantau and Jannis Pohlmann
Graph Drawing Library layered
\usegdlibrary{layered} % LATEX and plain TEX
\usegdlibrary[layered] % ConTEXt
A “layered” layout of a graph tries to arrange the nodes in consecutive horizontal layers (naturally, by
rotating the graph, this can be changed in to vertical layers) such that edges tend to be only between
nodes on adjacent layers. Trees, for instance, can always be laid out in this way. This method of laying
out a graph is especially useful for hierarchical graphs.
The method implemented in this library is often called the Sugiyama method, which is a rather advanced
method of assigning nodes to layers and positions on these layers. The same method is also used in
the popular GraphViz program, indeed, the implementation in Tik Z is based on the same pseudo-code
from the same paper as the implementation used in GraphViz and both programs will often generate
the same layout (but not always, as explained below). The current implementation is due to Jannis
Pohlmann, who implemented it as part of his Diploma thesis. Please consult this thesis for a detailed
explanation of the Sugiyama method and its history:
• Jannis Pohlmann, Configurable Graph Drawing Algorithms for the Ti kZ Graphics Description
Language, Diploma Thesis, Institute of Theoretical Computer Science, Univeristät zu Lübeck,
2011.
Available online via http://www.tcs.uni-luebeck.de/downloads/papers/2011/
2011-configurable-graph-drawing-algorithms-jannis-pohlmann.pdf
(Note that since the publication of this thesis some option names have been changed. Most noticeably, the option name layered drawing was changed to layered layout, which is somewhat
more consistent with other names used in the graph drawing libraries. Furthermore, the keys for
choosing individual algorithms for the different algorithm phases, have all changed.)
The Sugiyama methods lays out a graph in five steps:
1. Cycle removal.
2. Layer assignment (sometimes called node ranking).
3. Crossing minimization (also referred to as node ordering).
4. Node positioning (or coordinate assignment).
5. Edge routing.
It turns out that behind each of these steps there lurks an NP-complete problem, which means, in
practice, that each step is impossible to perform optimally for larger graphs. For this reason, heuristics
and approximation algorithms are used to find a “good” way of performing the steps.
A distinctive feature of Pohlmann’s implementation of the Sugiyama method for Tik Z is that the
algorithms used for each of the steps can easily be exchanged, just specify a different option. For the
user, this means that by specifying a different option and thereby using a different heuristic for one of
the steps, a better layout can often be found. For the researcher, this means that one can very easily
test new approaches and new heuristics without having to implement all of the other steps anew.
30.1
The Modular Sugiyama Method
/graph drawing/layered layout=hstringi
The layered layout is the key used to select the modular Sugiyama layout algorithm.
This algorithm consists of five consecutive steps, each of which can be configured independently of the
other ones (how this is done is explained later in this section). Naturally, the “best” heuristics are
selected by default, so there is typically no need to change the settings, but what is the “best” method
for one graph need not be the best one for another graph.
As can be seen in the first example, the algorithm will not only position the nodes of a graph, but will
also perform an edge routing. This will look visually quite pleasing if you add the rounded corners
option:
415
Examples
a
c
d
e
\tikz \graph [layered layout, sibling distance=7mm]
{
a -> {
b,
c -> { d, e, f }
} ->
h ->
a
};
b
f
h
a
c
d
e
\tikz [rounded corners] \graph [layered layout, sibling distance=7mm]
{
a -> {
b,
c -> { d, e, f }
} ->
h ->
a
};
b
f
h
/graph drawing/minimum layers=hnumber i
(initially 1)
The minimum number of levels that an edge must span. It is a bit of the opposite of the weight
parameter: While a large weight causes an edge to become shorter, a larger minimum layers value
causes an edge to be longer.
Example
a
\tikz \graph [layered layout] {
a -- {b [> minimum layers=3], c, d} -- e -- a;
};
d
c
b
e
(style)
/graph drawing/same layer
The same layer collection allows you to enforce that several nodes a on the same layer of a layered
layout (this option is also known as same rank). You use it like this:
Examples
b
a
\tikz \graph [layered layout] {
a -- b -- c -- d -- e;
c
e
d
{ [same layer] a, b };
{ [same layer] d, e };
};
416
Thompson
1972
Mashey
1976
1978
1980
Bourne
Formshell
esh
csh
vsh
1982
System-V
ksh
1984
1986
ksh-i
1988
KornShell
1990
tcl
tcsh
v9sh
Perl
rc
Bash
future
POSIX
ksh-POSIX
\tikz [rounded corners] \graph [layered layout] {
1972 -> 1976 -> 1978 -> 1980 -> 1982 -> 1984 -> 1986 -> 1988 -> 1990 -> future;
{
{
{
{
{
{
{
{
{
{
[same
[same
[same
[same
[same
[same
[same
[same
[same
[same
layer]
layer]
layer]
layer]
layer]
layer]
layer]
layer]
layer]
layer]
1972, Thompson };
1976, Mashey, Bourne },
1978, Formshell, csh },
1980, esh, vsh },
1982, ksh, "System-V" },
1984, v9sh, tcsh },
1986, "ksh-i" },
1988, KornShell ,Perl, rc },
1990, tcl, Bash },
"future", POSIX, "ksh-POSIX" },
Thompson -> { Mashey, Bourne, csh -> tcsh},
Bourne -> { ksh, esh, vsh, "System-V", v9sh -> rc, Bash},
{ "ksh-i", KornShell } -> Bash,
{ esh, vsh, Formshell, csh } -> ksh,
{ KornShell, "System-V" } -> POSIX,
ksh -> "ksh-i" -> KornShell -> "ksh-POSIX",
Bourne -> Formshell,
{ [edge={draw=none}]
Bash -> tcl,
KornShell -> Perl
}
};
30.2
Cycle Removal
The Sugiyama method works only on directed acyclic graphs. For this reason, if the input graph is not
(yet) acyclic, a number of edges need to be redirected so that acyclicity arises. In the following, the different
options that allow you to fine-tune this process are documented.
/graph drawing/depth first cycle removal=hstringi
Selects a cycle removal algorithm that is especially appropriate for graphs specified “by hand”.
When graphs are created by humans manually, one can make assumptions about the input graph that
would otherwise not be possible. For instance, it seems reasonable to assume that the order in which
nodes and edges are entered by the user somehow reflects the natural flow the user has had in mind for
the graph.
417
In order to preserve the natural flow of the input graph, Gansner et al. propose to remove cycles by
performing a series of depth-first searches starting at individual nodes in the order they appear in the
graph. This algorithm implicitly constructs a spanning tree of the nodes reached during the searches.
It thereby partitions the edges of the graph into tree edges and non-tree edges. The non-tree edges are
further subdivided into forward edges, cross edges, and back edges. Forward edges point from a tree
nodes to one of their descendants. Cross edges connect unrelated branches in the search tree. Back
edges connect descendants to one of their ancestors. It is not hard to see that reversing back edges will
not only introduce no new cycles but will also make any directed graph acyclic. Gansner et al. argue
that this approach is more stable than others in that fewer inappropriate edges are reversed compared
to other methods, despite the lack of a provable upper bound for the number of reversed edges.
See section 4.1.1 of Pohlmann’s Diplom thesis for more details.
This is the default algorithm for cycle removals.
/graph drawing/prioritized greedy cycle removal=hstringi
This algorithm implements a greedy heuristic of Eades et al. for cycle removal that prioritizes sources
and sinks.
See section 4.1.1 of Pohlmann’s Diploma theses for details.
/graph drawing/greedy cycle removal=hstringi
This algorithm implements a greedy heuristic of Eades et al. for cycle removal that prioritizes sources
and sinks.
See section 4.1.1 of Pohlmann’s Diploma theses for details.
/graph drawing/naive greedy cycle removal=hstringi
This algorithm implements a greedy heuristic of Berger and Shor for cycle removal. It is not really
compared to the other heuristics and only included for demonstration purposes.
See section 4.1.1 of Pohlmann’s Diploma theses for details.
/graph drawing/random greedy cycle removal=hstringi
This algorithm implements a randomized greedy heuristic of Berger and Shor for cycle removal. It, too,
is not really compared to the other heuristics and only included for demonstration purposes.
See section 4.1.1 of Pohlmann’s Diploma theses for details.
30.3
Layer Assignment (Node Ranking)
Algorithms for producing layered drawings place nodes on discrete layers from top to bottom. Layer
assignment is the problem of finding a partition so that for all edges e = (u, v) ∈ E(G) the equation
layer (u) < layer (v) holds. Such a partition is called a layering. This definition can be extended by introducing edge weights or priorities and minimum length constraints which has practical applications and allows
users to fine-tune the results.
For more details, please see Section 4.1.2 of Pohlmann’s Diploma thesis.
/graph drawing/linear optimization layer assignment=hstringi
This layer assigment method, due to Gasner et al., is based on a linear optimization problem.
For more details, please see Section 4.1.2 of Pohlmann’s Diploma thesis.
This is the default algorithm for layer assignments.
/graph drawing/minimum height layer assignment=hstringi
This layer assigment method minimizes the height of the resulting graph.
For more details, please see Section 4.1.3 of Pohlmann’s Diploma thesis.
30.4
Crossing Minimization (Node Ordering)
The number of edge crossings in a layered drawing is determined by the ordering of nodes at each of its layers.
Therefore, crossing minimization is the problem of reordering the nodes at each layer so that the overall
number of edge crossings is minimized. The crossing minimization step takes a proper layering where every
418
edge connects nodes in neighbored layers, allowing algorithms to minimize crossings layer by layer rather
than all at once. While this does not reduce the complexity of the problem, it does make it considerably
easier to understand and implement. Techniques based on such an iterative approach are also known as
layer-by-layer sweep methods. They are used in many popular heuristics due to their simplicity and the
good results they produce.
Sweeping refers to moving up and down from one layer to the next, reducing crossings along the way.
In layer-by-layer sweep methods, an initial node ordering for one of the layers is computed first. Depending
on the sweep direction this can either be the first layer or the last; in rare occasions the layer in the middle
is used instead. Followed by this, the actual layer-by-layer sweep is performed. Given an initial ordering
for the first layer L1 , a downward sweep first holds the nodes in L1 fixed while reordering the nodes in the
second layer L2 to reduce the number of crossings between L1 and L2 . It then goes on to reorder the third
layer while holding the second layer fixed. This is continued until all layers except for the first one have been
examined. Upward sweeping and sweeping from the middle work analogous.
Obviously, the central aspect of the layer-by-layer sweep is how the nodes of a specific layer are reordered
using a neighbored layer as a fixed reference. This problem is known as one-sided crossing minimization,
which unfortunately is NP-hard. In the following various heuristics to solve this problem are presented.
For more details, please see Section 4.1.4 of Pohlmann’s Diploma thesis.
/graph drawing/sweep crossing minimization=hstringi
Gansner et al. combine an initial ordering based on a depth-first search with the median and greedy
switch heuristics applied in the form of an alternating layer-by-layer sweep based on a weighted median.
For more details, please see Section 4.1.4 of Pohlmann’s Diploma thesis.
This is the default algorithm for crossing minimization.
30.5
Node Positioning (Coordinate Assignment)
The second last step of the Sugiyama method decides about the final x- and y-coordinates of the nodes.
The main objectives of this step are to position nodes so that the number of edge bends is kept small and
edges are drawn as vertically as possible. Another goal is to avoid node and edge overlaps which is crucial
in particular if the nodes are allowed to have non-uniform sizes. The y-coordinates of the nodes have no
influence on the number of bends. Obviously, nodes need to be separated enough geometrically so that they
do not overlap. It feels natural to aim at separating all layers in the drawing by the same amount. Large
nodes, however, may force node positioning algorithms to override this uniform level distance in order to
avoid overlaps.
For more details, please see Section 4.1.2 of Pohlmann’s Diploma thesis.
/graph drawing/linear optimization node positioning=hstringi
This node positioning method, due to Gasner et al., is based on a linear optimization problem.
For more details, please see Section 4.1.3 of Pohlmann’s Diploma thesis.
This is the default algorithm for layer assignments.
30.6
Edge Routing
The original layered drawing method described by Eades and Sugiyama in does not include the routing or
shaping of edges as a main step. This makes sense if all nodes have the same size and shape. In practical
scenarios, however, this assumption often does not hold. In these cases, advanced techniques may have to
be applied in order to avoid overlaps of nodes and edges.
For more details, please see Section 4.1.5 of Pohlmann’s Diploma thesis.
/graph drawing/polyline layer edge routing=hstringi
This edge routing algorithm uses polygonal lines to connect nodes.
For more details, please see Section 4.1.5 of Pohlmann’s Diploma thesis.
This is the default algorithm for edge routing.
419
31
Graph Drawing Algorithms: Force-Based Methods
by Till Tantau and Jannis Pohlmann
Graph Drawing Library force
\usegdlibrary{force} % LATEX and plain TEX
\usegdlibrary[force] % ConTEXt
Nature creates beautiful graph layouts all the time. Consider a spider’s web: Nodes are connected by
edges in a visually most pleasing manner (if you ignore the spider in the middle). The layout of a
spider’s web is created just by the physical forces exerted by the threads. The idea behind force-based
graph drawing algorithms is to mimic nature: We treat edges as threads that exert forces and simulate
into which configuration the whole graph is “pulled” by these forces.
When you start thinking about for a moment, it turns out that there are endless variations of the force
model. All of these models have the following in common, however:
• “Forces” pull and push at the nodes in different directions.
• The effect of these forces is simulated by iteratively moving all the nodes simultaneously a little in
the direction of the forces and by then recalculating the forces.
• The iteration is stopped either after a certain number of iterations or when a global energy minimum
is reached (a very scientific way of saying that nothing happens anymore).
The main difference between the different force-based approaches is how the forces are determined. Here
are some ideas what could cause a force to be exerted between two nodes (and there are more):
• If the nodes are connected by an edge, one can treat the edge as a “spring” that has a “natural
spring dimension.” If the nodes are nearer than the spring dimension, they are push apart; if they
are farther aways than the spring dimension, they are pulled together.
• If two nodes are connected by a path of a certain length, the nodes may “wish to be at a distance
proportional to the path length”. If they are nearer, they are pushed apart; if they are farther,
they are pulled together. (This is obviously a generalization of the previous idea.)
• There may be a general force field that pushes nodes apart (an electrical field), so that nodes do
not tend to “cluster”.
• There may be a general force field that pulls nodes together (a gravitational field), so that nodes
are not too loosely scattered.
• There may be highly nonlinear forces depending on the distance of nodes, so that nodes very near
to each get pushed apart strongly, but the effect wears of rapidly at a distance. (Such forces are
known as strong nuclear forces.)
• There rotational forces caused by the angles between the edges leaving a node. Such forces try
to create a perfect angular resolution (a very scientific way of saying that all angles at a node are
equal).
Force-based algorithms combine one or more of the above ideas into a single algorithm that uses “good”
formulas for computing the forces.
Currently, three algorithms are implemented in this library, two of which are from the first of the
following paper, while the third is from the third paper:
• Y. Hu. Efficient, high-quality force-directed graph drawing. The Mathematica Journal, 2006.
• C. Walshaw. A multilevel algorithm for force-directed graph drawing. In J. Marks, editor, Graph
Drawing, Lecture Notes in Computer Science, 1984:31–55, 2001.
Our implementation is described in detail in the following diploma thesis:
• Jannis Pohlmann, Configurable Graph Drawing Algorithms for the Ti kZ Graphics Description
Language, Diploma Thesis, Institute of Theoretical Computer Science, Univeristät zu Lübeck,
2011.
Online at http://www.tcs.uni-luebeck.de/downloads/papers/2011/
2011-configurable-graph-drawing-algorithms-jannis-pohlmann.pdf
420
In the future, I hope that most, if not all, of the force-based algorithms become “just configuration
options” of a general force-based algorithm similar to the way the modular Sugiyama method is implemented in the layered graph drawing library.
31.1
Controlling and Configuring Force-Based Algorithms
All force-based algorithms are based on a general pattern which we detail in the following. Numerous
options can be used to influence the behaviour of this general pattern; more specific options that apply only
to individual algorithms are explained along with these algorithms.
31.1.1
Start Configuration
Currently, the start configuration for force-based algorithms is a random distribution of the vertices. You
can influence it by changing the random seed:
\tikz \graph [random seed=10, spring layout] {
a -- {b, c, d} -- e -- f -- {g,h} -- {a,b,e};
};
c
a
g
d
f
e
b
h
\tikz \graph [random seed=11, spring layout] {
a -- {b, c, d} -- e -- f -- {g,h} -- {a,b,e};
};
d
a
g
c
f
e
h
b
Other methods, like a planar preembedding, are not implemented currently.
31.1.2
The Iterative Process and Cooling
/graph drawing/iterations=hnumber i
(initially 500)
Limits the number of iterations of algorithms for force-based layouts to hnumber i.
Depending on the characteristics of the input graph and the parameters chosen for the algorithm,
minimizing the system energy may require many iterations.
In these situations it may come in handy to limit the number of iterations. This feature can also be
useful to draw the same graph after different iterations and thereby demonstrate how the spring or
spring-electrical algorithm improves the drawing step by step.
The examples shows two drawings generated using two different iteration limits.
Examples
1
\tikz \graph [spring layout, iterations=10]
2
3
4
421
{ subgraph K_n [n=4] };
1
\tikz \graph [spring layout, iterations=500] { subgraph K_n [n=4] };
2
3
4
1
2
\tikz \graph [spring electrical layout, iterations=10]
{ subgraph K_n [n=4] };
3
4
2
1
3
4
\tikz \graph [spring electrical layout, iterations=500]
{ subgraph K_n [n=4] };
(initially 0)
/graph drawing/initial step length=hlengthi
This parameter specifies the amount by which nodes will be displaced in each iteration, initially. If set
to 0 (which is the default), an appropriate value is computed automatically.
/graph drawing/cooling factor=hnumber i
(initially 0.95)
This parameter helps in controlling how layouts evolve over time. It is used to gradually reduce the
step size between one iteration to the next.
A small positive cooling factor ≥ 0 means that the movement of nodes is quickly or abruptly reduced,
while a large cooling factor ≤ 1 allows for a smoother step by step layout refinement at the cost of
more iterations. The following example demonstrates how a smaller cooling factor may result in a
less balanced drawing. By default, Hu2006 spring, Hu2006 spring electrical, and Walshaw2000 spring
electrical use a cooling factor of 0.95.
Examples
a
c
\tikz \graph [spring layout, cooling factor=0.1]
{ a -> b -> c -> a };
b
a
c
\tikz \graph [spring layout, cooling factor=0.5]
{ a -> b -> c -> a };
b
/graph drawing/convergence tolerance=hnumber i
(initially 0.01)
All spring and spring-electrical algorithms implemented in the thesis terminate as soon as the maximum
movement of any node drops below k · htolerancei. This tolerance factor can be changed with the
convergence tolerance option:
Examples
422
6
1
3
2
4
7
\tikz \graph [spring layout, convergence tolerance=0.001]
{ { [clique] 1, 2 } -- 3 -- 4 -- { 5, 6, 7 } };
5
1
7
31.1.3
23
\tikz \graph [spring layout, convergence tolerance=1.0]
{ { [clique] 1, 2 } -- 3 -- 4 -- { 5, 6, 7 } };
4
56
Forces and Their Effects: Springs
The most important parameter of springs is their “natural length”, which can be configured using the generalpurpose node distance parameter. It is the “equilibrium length” of a spring between two nodes in the graph.
When an edge has this lenght, no forces will “push” or “pull” along the edge.
The following examples shows how a simple graph can be scaled by changing the node distance:
1
1
3
1
3
3
2 2
2
\tikz \graph [spring layout, node distance=7mm] { subgraph C_n[n=3] };
\tikz \graph [spring layout]
{ subgraph C_n[n=3] };
\tikz \graph [spring layout, node distance=15mm]{ subgraph C_n[n=3] };
1
1
1
3
3
3
2
2
2
\tikz \graph [spring electrical layout, node distance=0.7cm] { subgraph C_n[n=3] };
\tikz \graph [spring electrical layout]
{ subgraph C_n[n=3] };
\tikz \graph [spring electrical layout, node distance=1.5cm] { subgraph C_n[n=3] };
/graph drawing/spring constant=hnumber i
(initially 0.01)
The “spring constant” is a factor from Hooke’s law describing the “stiffness” of a spring. This factor
is used inside spring-based algorithms to determine how strongly edges “pull” and “push” at the nodes
they connect.
31.1.4
Forces and Their Effects: Electrical Repulsion
/graph drawing/electric charge=hnumber i
(initially 1)
Defines the electric charge of the node. The stronger the electric charge of a node the stronger the
repulsion between the node and others in the graph. A negative electric charge means that other
nodes are further attracted to the node rather than repulsed, although in theory this effect strongly
depends on how the spring electrical layout algorithm works. Two typcal effects of increasing the
electric charge are distortion of symmetries and an upscaling of the drawings.
Examples
423
3
4
\tikz \graph [spring electrical layout, horizontal=0 to 1]
{ 0 [electric charge=1] -- subgraph C_n [n=10] };
2
5
0
6
1
10
7
9
8
3
4
2
5
0
6
1
10
7
8
9
\tikz \graph [spring electrical layout, horizontal=0 to 1]
{ 0 [electric charge=5] -- subgraph C_n [n=10] };
1
2
4
\tikz \graph [spring electrical layout, horizontal=0 to 1]
{ [clique] 1 [electric charge=5], 2, 3, 4 };
3
/graph drawing/electric force order=hnumber i
(initially 1)
Sometimes, when drawing symmetric and mesh-like graphs, the peripheral distortion caused by longrange electric forces may be undesired. Some electric force models allow to reduce long-range forces
and distortion effects by increasing the order (epxonent) of electric forces. Values between 0 and 1 increase long-range electric forces and the scaling of the generated layouts. Value greater than 1 decrease
long-range electric forces and results in shrinking drawings.
/graph drawing/approximate remote forces=hbooleani
(default true)
Force based algorithms often need to compute a force for each pair of vertices, which, for larger numbers
of vertices, can lead to a significant time overhead. This problem can be addressed by approximating
these forces: For a vertex far removed from a cluster of vertices, instead of computing the force contribution of each vertex of the cluster indiviually, we form a sort of “supervertex” at the “gravitational
center” of the cluster and then compute only the force between this supervertex and the single vertex.
Remark: Currently, the implementation seems to be broken, at least the results are somewhat strange
when this key is used.
31.1.5
Coarsening
(default true, initially true)
/graph drawing/coarsen=hbooleani
Defines whether or not a multilevel approach is used that iteratively coarsens the input graph into graphs
G1 , . . . , Gl with a smaller and smaller number of nodes. The coarsening stops as soon as a minimum
number of nodes is reached, as set via the minimum coarsening size option, or if, in the last iteration,
the number of nodes was not reduced by at least the ratio specified via downsize ratio.
A random initial layout is computed for the coarsest graph Gl first. Afterwards, it is laid out by
computing the attractive and repulsive forces between its nodes.
424
In the subsequent steps, the previous coarse graph Gl−1 is restored and its node positions are interpolated
from the nodes in Gl . The graph Gl−1 is again laid out by computing the forces between its nodes. These
steps are repeated with Gl−2 , . . . , G1 until the original input graph G0 has been restored, interpolated
and laid out.
The idea behind this approach is that, by arranging recursively formed supernodes first and then interpolating and arranging their subnodes step by step, the algorithm is less likely to settle in a local energy
minimum (of which there can be many, particularly for large graphs). The quality of the drawings with
coarsening enabled is expected to be higher than graphics where this feature is not applied.
The following example demonstrates how coarsening can improve the quality of graph drawings generated with Walshaw’s algorihtm spring electrical layout’.
Example
1
2
2
1
3
3
4
4
6 5
5
7
7
6
\tikz \graph [spring electrical layout’, coarsen=false, vertical=3 to 4]
{
{ [clique] 1, 2 } -- 3 -- 4 -- { 5, 6, 7 }
};
\tikz \graph [spring electrical layout’, coarsen, vertical=3 to 4]
{
{ [clique] 1, 2 } -- 3 -- 4 -- { 5, 6, 7 }
};
/graph drawing/minimum coarsening size=hnumber i
(initially 2)
Defines the minimum number of nodes down to which the graph is coarsened iteratively. The first graph
that has a smaller or equal number of nodes becomes the coarsest graph Gl , where l is the number of
coarsening steps. The algorithm proceeds with the steps described in the documentation of the coarsen
option.
In the following example the same graph is coarsened down to two and four nodes, respectively. The
layout of the original graph is interpolated from the random initial layout and is not improved further
because the forces are not computed (0 iterations). Thus, in the two graphs, the nodes are placed at
exactly two and four coordinates in the final drawing.
Example
78
1234
5678
34
56
12
\tikz \graph [spring layout, iterations=0,
minimum coarsening size=2]
{ subgraph C_n [n=8] };
\tikz \graph [spring layout, iterations=0,
minimum coarsening size=4]
{ subgraph C_n [n=8] };
/graph drawing/downsize ratio=hnumber i
(initially 0.25)
Minimum ratio between 0 and 1 by which the number of nodes between two coarse graphs Gi and
Gi+1 need to be reduced in order for the coarsening to stop and for the algorithm to use Gi+1 as the
coarsest graph Gl . Aside from the input graph, the optimal value of downsize ratio mostly depends
on the coarsening scheme being used. Possible schemes are collapse independent edges and connect
independent nodes.
Increasing this option possibly reduces the number of coarse graphs computed during the coarsening
phase as coarsening will stop as soon as a coarse graph does not reduce the number of nodes substan425
tially. This may speed up the algorithm but if the size of the coarsest graph Gl is much larger than
minimum coarsening size, the multilevel approach may not produce drawings as good as with a lower
downsize ratio.
Example
2
5
7
3
31
4
2
64
31.2
1
5
7
6
% 1. ratio too high, coarsening stops early, benefits are lost
\tikz \graph [spring electrical layout’,
downsize ratio=1.0,
node distance=7mm, vertical=3 to 4]
{ { [clique] 1, 2 } -- 3 -- 4 -- { 5, 6, 7 } };
% 2. ratio set to default, coarsening benefits are visible
\tikz \graph [spring electrical layout’,
downsize ratio=0.2,
node distance=7mm, vertical=3 to 4]
{ { [clique] 1, 2 } -- 3 -- 4 -- { 5, 6, 7 } };
Spring Layouts
/graph drawing/spring layout=hstringi
This key selects Hu’s 2006 spring layout with appropriate settings for some parameters.
/graph drawing/spring Hu 2006 layout=hstringi
Implementation of a spring graph drawing algorithm based on a paper by Hu.
• Y. Hu. Efficient, high-quality force-directed graph drawing. The Mathematica Journal, 2006.
There are some modifications compared to the original algorithm, see the Diploma thesis of Pohlmann
for details.
31.3
Spring Electrical Layouts
/graph drawing/spring electrical layout=hstringi
This key selects Hu’s 2006 spring electrical layout with appropriate settings for some parameters.
/graph drawing/spring electrical layout’=hstringi
This key selects Walshaw’s 2000 spring electrical layout with appropriate settings for some parameters.
/graph drawing/spring electrical Hu 2006 layout=hstringi
Implementation of a spring electrical graph drawing algorithm based on a paper by Hu.
• Y. Hu. Efficient, high-quality force-directed graph drawing. The Mathematica Journal, 2006.
There are some modifications compared to the original algorithm, see the Diploma thesis of Pohlmann
for details.
/graph drawing/spring electrical Walshaw 2000 layout=hstringi
Implementation of a spring electrical graph drawing algorithm based on a paper by Walshaw.
• C. Walshaw. A multilevel algorithm for force-directed graph drawing. In J. Marks, editor, Graph
Drawing, Lecture Notes in Computer Science, 1984:31–55, 2001.
The following modifications compared to the original algorithm were applied:
• An iteration limit was added.
• The natural spring length for all coarse graphs is computed based on the formula presented by
Walshaw, so that the natural spring length of the original graph (coarse graph 0) is the same as
the value requested by the user.
• Users can define custom node and edge weights.
• Coarsening stops when V(G_i+1)/V(G_i) < p where p = 0.75.
426
• Coarsening stops when the maximal matching is empty.
• Theruntime of the algorithm is improved by use of a quadtree data structure like Hu does in his
algorithm.
• A limiting the number of levels of the quadtree is not implemented.
427
32
Graph Drawing Algorithms: Circular Layouts
by Till Tantau
Graph Drawing Library circular
\usegdlibrary{circular} % LATEX and plain TEX
\usegdlibrary[circular] % ConTEXt
“Circular” graph drawing algorithms arrange the nodes of a graph on one of more circles.
/graph drawing/simple necklace layout=hstringi
This simple layout arranges the nodes in a circle, which is especially useful for drawing, well, circles
of nodes. The name simple necklace layout is reminiscent of the more general “necklace layout,” a
term coined by Speckmann and Verbeek in their paper
• Bettina Speckmann and Kevin Verbeek, Necklace Maps, IEEE Transactions on Visualization and
Computer Graphics, 16(6):881–889, 2010.
For a simple necklace layout, the centers of the nodes are placed on a counter-clockwise circle,
starting with the first node at the grow direction (for grow’, the circle is clockwise). The order of the
nodes is the order in which they appear in the graph, the edges are not taken into consideration, unless
the componentwise option is given.
x1
x2
xn
x3
xn−1
\tikz[>=spaced stealth’]
\graph [simple necklace layout, grow’=down, node sep=1em,
nodes={draw,circle}, math nodes]
{
x_1 -> x_2 -> x_3 -> x_4 ->
x_5 -> "\dots"[draw=none] -> "x_{n-1}" -> x_n -> x_1
};
x4
...
x5
When you give the componentwise option, the graph will be decomposed into connected components,
which are then laid out individually and packed using the usual component packing mechanisms:
\tikz \graph [simple necklace layout] {
a -- b -- c -- d -- a,
1 -- 2 -- 3 -- 1
};
a
3
b
c
2
1
d
a
b
1
d
2
3
\tikz \graph [simple necklace layout, componentwise] {
a -- b -- c -- d -- a,
1 -- 2 -- 3 -- 1
};
c
The nodes are placed in such a way that
1. The (angular) distance between the centers of consecutive nodes is at least node distance,
2. the distance between the borders of consecutive nodes is at least node sep, and
3. the radius is at least radius.
The radius of the circle is chosen near-minimal such that the above properties are satisfied. To be more
precise, if all nodes are circles, the radius is chosen optimally while for, say, rectangular nodes there
may be too much space between the nodes in order to satisfy the second condition.
Examples
428
1
7
2
6
3
\tikz \graph [simple necklace layout,
node sep=0pt, node distance=0pt,
nodes={draw,circle}]
{ 1 -- 2 [minimum size=30pt] -- 3 -4 [minimum size=50pt] -- 5 [minimum size=40pt] -- 6 -- 7 };
5
4
1
7
2
6
3
5
4
1
7
2
6
3
\begin{tikzpicture}[radius=1.25cm]
\graph [simple necklace layout,
node sep=0pt, node distance=0pt,
nodes={draw,circle}]
{ 1 -- 2 [minimum size=30pt] -- 3 -4 [minimum size=50pt] -- 5 [minimum size=40pt] -- 6 -- 7 };
\draw [red] (0,-1.25) circle [];
\end{tikzpicture}
\tikz \graph [simple necklace layout,
node sep=0pt, node distance=1cm,
nodes={draw,circle}]
{ 1 -- 2 [minimum size=30pt] -- 3 -4 [minimum size=50pt] -- 5 [minimum size=40pt] -- 6 -- 7 };
5
4
1
7
2
6
3
\tikz \graph [simple necklace layout,
node sep=2pt, node distance=0pt,
nodes={draw,circle}]
{ 1 -- 2 [minimum size=30pt] -- 3 -4 [minimum size=50pt] -- 5 [minimum size=40pt] -- 6 -- 7 };
5
4
1
2
\tikz \graph [simple necklace layout,
node sep=0pt, node distance=0pt,
nodes={rectangle,draw}]
{ 1 -- 2 [minimum size=30pt] -- 3 -4 [minimum size=50pt] -- 5 [minimum size=40pt] -- 6 -- 7 };
7
6
3
5
4
429
33
Graph Drawing Layouts: Phylogenetic Trees
by Sarah Mäusle and Till Tantau
Graph Drawing Library phylogenetics
\usegdlibrary{phylogenetics} % LATEX and plain TEX
\usegdlibrary[phylogenetics] % ConTEXt
A phylogenetic tree (or network) depicts the evolutionary histroy of species or, more generally, so called
taxa. The present library includes a number of algorithms for drawing phylogenetic trees.
/graph drawing/phylogenetic tree layout=hstringi
Layout for drawing phylogenetic trees.
...
Example
a
b
c
d
e
f
g
\tikz \graph [phylogenetic tree layout, upgma,
distance matrix={
0 4 9 9 9 9 9
4 0 9 9 9 9 9
9 9 0 2 7 7 7
9 9 2 0 7 7 7
9 9 7 7 0 3 5
9 9 7 7 3 0 5
9 9 7 7 5 5 0}]
{ a, b, c, d, e, f, g };
33.1
Generating a Phylogenetic Tree
...
When a phylogenetic tree is generated, new nodes and edges get created. In order to give you a chance
at styling them, the following styles are executed:
(style, no value)
/graph drawing/phylogenetic inner node
The style is added every newly created inner node. In this manual, this key is set to:
\pgfgdset{phylogenetic inner node/.style={
/tikz/.cd, draw, circle, inner sep=0pt, minimum size=5pt
}
}
(style, no default)
/graph drawing/phylogenetic edge=hlengthi
The style is added every newly created phylogenetic edge. The hlengthi will be set to the computed
evolutionary length of the edge. In this manual, this key is set to:
\pgfgdset{phylogenetic edge/.style={
/tikz/.cd, thick, rounded corners
}
}
430
/graph drawing/phylogenetic tree by author=hstringi
When this key is used, the phylogenetic tree must be specified by the author (rather than being generated
algorithmically).
A spanning tree of the input graph will be computed first (it must be connected, otherwise errors will
result). The evolutionary length of the edges must be specified through the use of the length key for
each edge.
Example
a
\tikz \graph [phylogenetic tree layout] {
a -- {
b [>length=2] --[length=1] { c, d },
e [>length=3]
}
};
b
e
d
c
/graph drawing/unweighted pair group method using arithmetic averages=hstringi
The UPGMA (Unweighted Pair Group Method using arithmetic Averages) algorithm of Sokal and
Michener, 1958. It generates a graph on the basis of such a distance matrix by generating nodes and
computing the edge lengths.
This algorithm uses a distance matrix, ideally an ultrametric one, to compute the graph.
Example
\tikz \graph [phylogenetic tree layout, sibling distance=0pt, sibling sep=2pt,
unweighted pair group method using arithmetic averages,
distance matrix={
0 4 9 9 9 9 9
4 0 9 9 9 9 9
9 9 0 2 7 7 7
9 9 2 0 7 7 7
9 9 7 7 0 3 5
9 9 7 7 3 0 5
9 9 7 7 5 5 0}]
{ a, b, c, d, e, f, g };
a b c d e f g
/graph drawing/upgma=hstringi
An shorthand for unweighted pair group method using arithmetic averages
/graph drawing/balanced minimum evolution=hstringi
The BME (Balanced Minimum Evolution) algorithm tries to minimize the total tree length.
This algorithm is from Desper and Gascuel, Fast and Accurate Phylogeny Reconstruction Algorithms
Based on the Minimum-Evolution Principle, 2002. The tree is built in a way that minimizes the total
tree length. The leaves are inserted into the tree one after another, creating new edges and new nodes.
After every insertion the distance matrix has to be updated.
Example
431
a
b
c
d
g
e
f
\tikz \graph [phylogenetic tree layout,
balanced minimum evolution,
grow’=right, sibling distance=0pt,
distance matrix={
0 4 9 9 9 9 9
4 0 9 9 9 9 9
9 9 0 2 7 7 7
9 9 2 0 7 7 7
9 9 7 7 0 3 5
9 9 7 7 3 0 5
9 9 7 7 5 5 0}]
{ a, b, c, d, e, f, g };
/graph drawing/balanced nearest neighbour interchange=hstringi
The BNNI (Balanced Nearest Neighbour Interchange) is a postprocessing algorithm for phylogenetic
trees. It swaps two distant 3-subtrees if the total tree length is reduced by doing so, until no such swaps
are left.
This algorithm is from Desper and Gascuel, Fast and Accurate Phylogeny Reconstruction Algorithms
Based on the Minimum-Evolution Principle, 2002.
/graph drawing/no phylogenetic tree optimization=hstringi
Switches off any phylogenetic tree optimization.
33.2
Laying out the Phylogram
/graph drawing/rooted rectangular phylogram=hstringi
A rooted rectangular phylogram is...
...
Example
c
a
d
g
e
f
b
432
\tikz \graph [phylogenetic tree layout,
rooted rectangular phylogram,
balanced minimum evolution,
distance matrix={
0 4 9 9 9 9 9
4 0 9 9 9 9 9
9 9 0 2 7 7 7
9 9 2 0 7 7 7
9 9 7 7 0 3 5
9 9 7 7 3 0 5
9 9 7 7 5 5 0}]
{ a, b, c, d, e, f, g };
/graph drawing/rectangular phylogram=hstringi
An alias for rooted rectangular phylogram
/graph drawing/rooted straight phylogram=hstringi
A rooted straight phylogram is...
...
Example
f
e
g
d
c
b
a
\tikz \graph [phylogenetic tree layout,
rooted straight phylogram,
balanced minimum evolution, grow=right,
distance matrix={
0 4 9 9 9 9 9
4 0 9 9 9 9 9
9 9 0 2 7 7 7
9 9 2 0 7 7 7
9 9 7 7 0 3 5
9 9 7 7 3 0 5
9 9 7 7 5 5 0}]
{ a, b, c, d, e, f, g };
/graph drawing/straight phylogram=hstringi
An alias for rooted straight phylogram
/graph drawing/unrooted rectangular phylogram=hstringi
A unrooted rectangular phylogram is...
...
Example
433
d
f
c
e
b
g
a
\tikz \graph [phylogenetic tree layout,
unrooted rectangular phylogram,
balanced minimum evolution, grow=right,
distance matrix={
0 4 9 9 9 9 9
4 0 9 9 9 9 9
9 9 0 2 7 7 7
9 9 2 0 7 7 7
9 9 7 7 0 3 5
9 9 7 7 3 0 5
9 9 7 7 5 5 0}]
{ a, b, c, d, e, f, g };
/graph drawing/unrooted straight phylogram=hstringi
A unrooted straight phylogram is...
...
Example
f
e
d
c
b
g
a
\tikz \graph [phylogenetic tree layout,
unrooted straight phylogram,
balanced minimum evolution, grow=right,
distance matrix={
0 4 9 9 9 9 9
4 0 9 9 9 9 9
9 9 0 2 7 7 7
9 9 2 0 7 7 7
9 9 7 7 0 3 5
9 9 7 7 3 0 5
9 9 7 7 5 5 0}]
{ a, b, c, d, e, f, g };
/graph drawing/evolutionary unit length=hlengthi
(initially 1cm)
Specifies how long a “unit” of evolutionary time should be on paper. For instance, if two nodes in a
phylogenetic tree have an evolutionary distance of 3 and this length is set to 1cm, then they will be 3cm
apart in a straight-line phylogram.
(This key used to be called distance scaling factor.)
434
34
Graph Drawing Algorithms: Edge Routing
by Till Tantau
Graph Drawing Library routing
\usegdlibrary{routing} % LATEX and plain TEX
\usegdlibrary[routing] % ConTEXt
This library contains algorithms for routing edges through a graph.
/graph drawing/necklace routing=hstringi
Bends all edges of a graph that lie on “necklaces” along these necklaces.
Some graph drawing algorithms lay out some or all nodes along a path, which is then called a necklace.
For instance, the simple necklace layout places all nodes on a circle and that circle is the “necklace.”
When the necklace rounting edge routing algorithm is selected, all edges that connect subsequent
nodes on such a necklace are bend in such a way that the “follow the necklace path.” In the example
case, this will cause all edges that connect adjacent nodes to become arcs on of the circle on which the
nodes lie.
Note that local edge routing options for an edge may overrule the edge routing computed by the
algorithm as in the edge from 6 to 7 in the example.
Example
1
2
\tikz \graph [simple necklace layout, node distance=1.5cm,
necklace routing,
nodes={draw,circle}, edges={>={Stealth[round,sep,bend]}}]
{ 1 -> 2 [minimum size=30pt] <- 3 <-> 4 -5 -- 6 -- [bend left] 7 -- 1 -- 4 };
7
3
6
4
5
435
35
The Algorithm Layer
by Till Tantau
35.1
Overview
The present section is addressed at readers interested in implementing new graph drawing algorithms for the
graph drawing system. Obviously, in order to do so, you need to have an algorithm in mind and also some
programming skills; but fortunately only in the Lua programming language: Even though the graph drawing
system was originally developed as an extension of Tik Z, is has been restructured so that the “algorithm
layer” where you define algorithms is scrupulously separated from Tik Z. In particular, an algorithm declared
and implemented on this layer can be used in with every “display layers,” see Section 37, without change.
Nevertheless, in the following we will use the Tik Z display layer and syntax in our examples.
Normally, new graph drawing algorithms can and must be implemented in the Lua programming language, which is a small, easy-to-learn (and quite beautiful) language integrated into current versions of TEX.
However, as explained in Section 36, you can also implement algorithms in C or C++ (and, possibly, in the
future also in other languages), but this comes at a great cost concerning portability. In the present section,
I assume that you are only interested in writing an algorithm using Lua.
In the following, after a small “hello world” example of graph drawing and a discussion of technical details
like how to name files so that TEX will find them, we have a look at the main parts of the algorithm layer:
• Section 35.3 gives and overview of the available namespaces and also of naming conventions used in
the graph drawing system.
• Section 35.4 explores what graph drawing scopes “look like on the algorithm layer.” As the graph of a
graph drawing scope is being parsed on the display layer, a lot of information is gathered: The nodes
and edges of the graph are identified and the object-oriented model is built, but other information is
also collected. For instance, a sequence of events is created during the parsing process. As another
example, numerous kinds of collections may be identified by the parser. The parsed graph together
with the event sequence and the collections are all gathered in a single table, called the scope table of
the current graph drawing scope. Algorithms can access this table to retrieve information that goes
beyond the “pure” graph model.
One entry in this table is of particular importance: The syntactic digraph. While most graph drawing
algorithms are not really interested in the “details” of how a graph was specified, for some algorithms
it makes a big difference whether you write a -> b or b <- a in your specification of the graph. These
algorithms can access the “fine details” of how the input graph was specified through the syntactic
digraph; all other algorithms can access their digraph or ugraph fields and do not have to worry about
the difference between a -> b and b <- a.
• Section 35.5 explains the object-oriented model of graphs used throughout the graph drawing system.
Graph drawing algorithms do not get the “raw” specification used by the user to specify a graph (like
{a -> {b,c}} in the graph syntax). Instead, what a graph drawing algorithm sees is “just” a graph
object that provides methods for accessing the vertices and arcs.
• Section 35.6 explains how the information in the graph drawing scope is processed. One might expect
that we simply run the algorithm selected by the user; however, things are more involved in practice.
When the layout of a graph needs to be computed, only very few algorithms will actually be able to
compute positions for the nodes of every graph. For instance, most algorithms implicitly assume that
the input graph is connected; algorithms for computing layouts for trees assume that the input is, well,
a tree; and so on. For this reason, graph drawing algorithms will not actually need the original input
graph as their input, but some transformed version of it. Indeed, all graph drawing algorithms are
treated as graph transformations by the graph drawing engine.
This section explains how transformations are chosen and which transformations are applied by default.
• Section 35.7 documents the interface-to-algorithm class. This interface encapsulates all that an algorithm “sees” of the graph drawing system (apart from the classes in model and lib).
• Section 35.8 provides a number of complete examples that show how graph drawing algorithms can,
actually, be implemented.
436
• Section 35.9 documents the different libraries functions that come with the graph drawing engine. For
instance, there are library functions for computing the (path) distance of nodes in a graph; a parameter
that is needed by some algorithms.
35.2
Getting Started
In this section, a “hello world” example of a graph drawing algorithm is given, followed by an overview of
the organization of the whole engine.
35.2.1
The Hello World of Graph Drawing
Let us start our tour of the algorithm layer with a “hello world” version of graph drawing: An algorithm that
simply places all nodes of a graph in a circle of a fixed radius. Naturally, this is not a particularly impressive
or intelligent graph drawing algorithm; but neither is the classical “hello world”. . . Here is a minimal version
of the needed code (this is not the typical way of formulating the code, but it is the shortest; we will have a
look at the more standard and verbose way in a moment):
pgf.gd.interface.InterfaceToAlgorithms.declare {
key = "very simple demo layout",
algorithm = {
run =
function (self)
local alpha = (2 * math.pi) / #self.ugraph.vertices
for i,vertex in ipairs(self.ugraph.vertices) do
vertex.pos.x = math.cos(i * alpha) * 25
vertex.pos.y = math.sin(i * alpha) * 25
end
end
}
}
This code declares a new algorithm (very simple demo layout) and includes an implementation of
the algorithm (through the run field of the algorithm field). When the run method is called, the self
parameter will contain the to-be-drawn graph in its ugraph field. It is now the job of the code to modify
the positions of the vertices in this graph (in the example, this is done by assigning values to vertex.pos.x
and vertex.pos.y).
In order to actually use the algorithm, the above code first needs to be executed somehow. For Tik Z, one
can just call \directlua on it or put it in a file and then use \directlua plus require (a better alternative)
or you put it in a file like simpledemo.lua and use \usegdlibrary{simpledemo} (undoubtedly the “best”
way). For another display layer, like a graphical editor, the code could also be executed through the use of
require.
Executing the code “just” declares the algorithm, this is what the declare function does. Inside some
internal tables, the algorithm layer will store the fact that a very simple demo layout is now available.
The algorithm layer will also communicate with the display layer through the binding layer to advertise this
fact to the “user.” In the case of Tik Z, this means that the option key very simple demo layout becomes
available at this point and we can use it like this:
d
b
f
a
\tikz [very simple demo layout]
\graph { f -> c -> e -> a -> {b -> {c, d, f}, e -> b}};
c
e
It turns out, that our little algorithm is already more powerful than one might expect. Consider the
following example:
d
a
1
c
\tikz [very simple demo layout, componentwise]
\graph {
1 -> 2 ->[orient=right] 3 -> 1;
a -- b --[orient=45] c -- d -- a;
};
b
2
3
437
Note that, in our algorithm, we “just” put all nodes on a circle around the origin. Nevertheless, the graph
gets decomposed into two connected components, the components are rotated so that the edge from node 2
to node 3 goes from left to right and the edge from b to c goes up at an angle of 45◦ , and the components
are placed next to each other so that some spacing is achieved.
The “magic” that achieves all this behind the scenes is called “graph transformations.” They will heavily
pre- and postprocess the input and output of graph drawing algorithms to achieve the above results.
Naturally, some algorithms may not wish their inputs and/or outputs to be “tampered” with. An algorithm can easily configure which transformations should be applied, by passing appropriate options to
declare.
35.2.2
Declaring an Algorithm
Let us now have a look at how one would “really” implement the example algorithm. First of all, we place
our algorithm in a separate file called, say, ExampleLayout.lua. This way, by putting it in a separate file,
all display layers can easily install the algorithm at runtime by saying require "ExampleLayout".
Next, the declare function is needed quite often, so it makes sense to create a short local name for it:
-- This is the file ExampleLayout.lua
local declare = require "pgf.gd.interface.InterfaceToAlgorithms".declare
The declare function is the work-horse of the algorithm layer. It takes a table that contains at least a
key field, which must be a unique string, and some other fields that specify in more detail what kind of key
is declared. Once declared through a call of declare, the “key” can be used on the display layer.
For declaring an algorithm, the table passed to declare must contain a field algorithm. This field, in
turn, must (normally) be set to a table that will become the algorithm class. In the above example, our
algorithm was so simple that we could place the whole definition of the class inside the call of declare, but
normally the class is defined in more detail after the call to declare:
local ExampleClass = {}
-- A local variable holding the class table
declare {
key = "very simple demo layout",
algorithm = ExampleClass
}
function ExampleClass:run ()
local alpha = (2 * math.pi) / #self.ugraph.vertices
...
end
The effect of the declare will be that the table stored in ExampleClass is setup to form a class in the
sense of object-oriented programming. In particular, a static new function is installed.
Now, whenever the user uses the key very simple demo layout on a graph, at some point the graph
drawing engine will create a new instance of the ExampleClass using new and will then call the run method
of this class. The class can have any number of other methods, but new and run are the only ones directly
called by the graph drawing system.
35.2.3
The Run Method
The run method of an algorithm classes lies at the heart of any graph drawing algorithm. This method will
be called whenever a graph needs to be laid out. Upon this call, the self object will have some important
fields set:
• ugraph This stands for “undirected graph” and is the “undirected” version of the to-be-laid out graph.
In this graph, whenever there is an arc between u and v, there is also an arc between v and u. It is
obtained by considering the syntactic digraph and then “forgetting” about the actual direction of the
edges.
When you have set certain preconditions in your algorithm class, like connected=true, the ugraph
will satisfy these conditions. In particular, the ugraph typically will not be the underlying undirected
graph of the complete syntactic digraph, but rather of some part of it. The use of (sub)layouts will
also modify the syntactic digraph is fancy ways.
Refer to this graph whenever your algorithm is “most comfortable” with an undirected graph, as is the
case for instance for most force-base algorithms.
438
• digraph This stands for “directed graph” and is the “semantically directed” version of the to-be-laid
out graph. Basically, when happens is that reverse edges in the syntactic digraph (an edge like b "
2. "--"
3. "<-"
4. "<->"
5. "-!-"
456
Field head
The head vertex of this edge.
Field tail
The tail vertex of this edge.
Field event
The creation Event of this edge.
Field options
A table of options that contains user-defined options.
Field direction
One of the directions named above.
Field path
A Path object that describes the path of the edge. The path’s coordinates are interpreted absolutely.
Field generated_options
This is an options array that is generated by the algorithm. When the edge is rendered later on,
this array will be passed back to the display layer. The syntax is the same as for the declare_parameter_sequence function, see InterfaceToAlgorithms.
Alphabetical method summary:
function Edge.new (values)
function Edge:headAnchorForEdgePath ()
function Edge:setPolylinePath (coordinates)
function Edge:tailAnchorForEdgePath ()
function Edge.new(values)
Create a new edge. The initial parameter allows you to setup some initial values.
Usage:
local v = Edge.new { tail = v1, head = v2 }
Parameters: 1. initial Values to override defaults. –
Returns: 1. A new edge object.
function Edge:tailAnchorForEdgePath()
This method returns a “coordinate factory” that can be used as the coordinate of a moveto at the
beginning of a path starting at the tail of the arc. Suppose you want to create a path starting at the
tail vertex, going to the coordinate (10, 10) and ending at the head vertex. The trouble is that when you
create the path corresponding to this route, you typically do not know where the tail vertex is going to
be. In this case, you use this method to get a function that will, later on, compute the correct position
of the anchor as needed.
Note that you typically do not use this function, but use the corresponding function of the Arc class.
Use this function only if there are multiple edges between two vertices that need to be routed differently.
Here is the code you would use to create the abovementioned path:
local a = g:connect(tail,head)
local e = a.syntactic_edges[1]
...
e.path = Path.new()
e.path:appendMoveto(e:tailAnchorForEdgePath())
e.path:appendLineto(10, 10)
e.path:appendLineto(e:headAnchorForEdgePath())
As for the Arc class, you can also setup a polyline more easily:
e:setPolylinePath { Coordinate.new (10, 10) }
457
function Edge:headAnchorForEdgePath()
See Arc:tailAnchorForArcPath.
function Edge:setPolylinePath(coordinates)
Setup the path field of an edge in such a way that it corresponds to a sequence of straight line segments
starting at the tail’s anchor and ending at the head’s anchor.
Parameters: 1. coordinates An array of Coordinates through which the line will go through.
35.5.5
Collections
Lua table Collection (declared in pgf.gd.model.Collection)
A collection is essentially a subgraph of a graph, that is, a “collection” of some nodes and some edges
of the graph. The name “collection” was chosen over “subgraph” since the latter are often thought of
as parts of a graph that are rendered in a special way (such as being surrounded by a rectangle), while
collections are used to model such diverse things as hyperedges, sets of vertices that should be on the
same level in a layered algorithm, or, indeed, subgraphs that are rendered in a special way.
Collections are grouped into “kinds.” All collections of a given kind can be accessed by algorithms
through an array whose elements are the collections. On the displya layer, for each kind a separate key
is available to indicate that a node or an edge belongs to a collection.
Collections serve two purposes: First, they can be seen as “hints” to graph drawing algorithms that
certain nodes and/or edges “belong together”. For instance, collections of kind same layer are used by
the Sugiyama algorithm to group together nodes that should appear at the same height of the output.
Second, since collections are also passed back to the display layer in a postprocessing step, they can be
used to render complicated concepts such as hyperedges (which are just collections of nodes, after all)
or subgraphs.
Field kind
The “kind” of the collection.
Field vertices
A lookup table of vertices (that is, both an array with the vertices in the order in which they appear
as well as a table such that vertices[vertex] == true whenever vertex is present in the table.
Field edges
A lookup table of edges (not arcs!).
Field options
An options table. This is the table of options that was in force when the collection was created.
Field child_collections
An array of all collections that are direct children of this collection (that is, they were defined while
the current collection was the most recently defined collection on the options stack). However, you
should use the methods children, descendants, and so to access this field.
Field parent_collection
The parent collection of the current colleciton. This field may be nil in case a collection has no
parent.
Field event
An Event object that was create for this collection. Its kind will be "collection" while its
parameter will be the collection kind.
Alphabetical method summary:
function Collection.new (t)
function Collection:childrenOfKind (kind)
function Collection:children ()
function Collection:descendantsOfKind (kind)
function Collection:descendants ()
458
function Collection.new(t)
Creates a new collection. You should not call this function directly, it is called by the interface classes.
Parameters: 1. t A table of initial values. The field t.kind must be a nonempty string.
Returns: 1. The new collection
function Collection:children()
A collection can have any number of child collections, which are collections nested inside the collection.
You can access the array of these children through this method. You may not modify the array returned
by this function.
Returns: 1. The array of children of self.
function Collection:childrenOfKind(kind)
This method works like the children method. However, the tree of collections is, conceptually, contracted by considering only these collections that have the kind given as parameter. For instance, if
self has a child collection of a kind different from kind, but this child collection has, in turn, a child
collection of kind kind, this latter child collection will be included in the array – but not any of its child
collections.
Parameters: 1. kind The collection kind to which the tree of collections should be restricted.
Returns: 1. The array of children of self in this contracted tree.
function Collection:descendants()
The descendants of a collection are its children, plus their children, plus their children, and so on.
Returns: 1. An array of all descendants of self. It will be in preorder.
function Collection:descendantsOfKind(kind)
The descendants of a collection of the given kind.
Parameters: 1. kind A colleciton kind.
Returns: 1. An array of all descendants of self of the given kind.
35.5.6
Coordinates, Paths, and Transformations
Lua table Coordinate (declared in pgf.gd.model.Coordinate)
A Coordinate models a position on the drawing canvas.
It has an x field and a y field, which are numbers that will be interpreted as TEX points (1/72.27th of
an inch). The x-axis goes right and the y-axis goes up.
Field x
Field y
There is also a static field called origin that is always equal to the origin.
Alphabetical method summary:
function Coordinate.__add (a,b)
function Coordinate.__div (a,b)
function Coordinate.__mul (a,b)
function Coordinate.__sub (a,b)
function Coordinate.__unm (a)
function Coordinate.boundingBox (array)
function Coordinate.new (x,y)
function Coordinate:apply (t)
function Coordinate:clone ()
function Coordinate:moveTowards (c,f)
function Coordinate:normalized ()
function Coordinate:normalize ()
459
function Coordinate:norm ()
function Coordinate:scale (s)
function Coordinate:shiftByCoordinate (c)
function Coordinate:shift (a,b)
function Coordinate:unshiftByCoordinate (c)
function Coordinate:unshift (a,b)
function Coordinate.new(x,y)
Creates a new coordinate.
Parameters: 1. x The x value 2. y The y value
Returns: 1. A coordinate
function Coordinate:clone()
Creates a new coordinate that is a copy of an existing one.
Returns: 1. A new coordinate at the same location as self
function Coordinate:apply(t)
Apply a transformation matrix to a coordinate, see pgf.gd.lib.Transform for details.
Parameters: 1. t A tansformation.
function Coordinate:shift(a,b)
Shift a coordinate
Parameters: 1. a An x offset 2. b A y offset
function Coordinate:unshift(a,b)
“Unshift” a coordinate (which is the same as shifting by the inversed coordinate; only faster).
Parameters: 1. a An x offset 2. b A y offset
function Coordinate:shiftByCoordinate(c)
Like shift, only for coordinate parameters.
Parameters: 1. c Another coordinate. The x- and y-values of self are increased by the x- and y-values
of this coordinate.
function Coordinate:unshiftByCoordinate(c)
Like unshift, only for coordinate parameters.
Parameters: 1. c Another coordinate.
function Coordinate:moveTowards(c,f)
Moves the coordinate a fraction of f along a straight line to c.
Parameters: 1. c Another coordinate 2. f A fraction
function Coordinate:scale(s)
Scale a coordinate by a factor
Parameters: 1. s A factor.
function Coordinate.__add(a,b)
Add two coordinates, yielding a new coordinate. Note that it will be a lot faster to call shift, whenever
this is possible.
Parameters: 1. a A coordinate 2. b A coordinate
function Coordinate.__sub(a,b)
Subtract two coordinates, yielding a new coordinate. Note that it will be a lot faster to call unshift,
whenever this is possible.
Parameters: 1. a A coordinate 2. b A coordinate
460
function Coordinate.__unm(a)
The unary minus (mirror the coordinate against the origin).
Parameters: 1. a A coordinate
function Coordinate.__mul(a,b)
The multiplication operator. Its effect depends on the parameters: If both are coordinates, their dotproduct is returned. If exactly one of them is a coordinate and the other is a number, the scalar multiple
of this coordinate is returned.
Parameters: 1. a A coordinate or a scalar 2. b A coordinate or a scalar
Returns: 1. The dot product or scalar product.
function Coordinate.__div(a,b)
The division operator. Returns the scalar division of a coordinate by a scalar.
Parameters: 1. a A coordinate 2. b A scalar (not equal to zero).
Returns: 1. The scalar product or a * (1/b).
function Coordinate:norm()
The norm function. Returns the norm of a coordinate.
Parameters: 1. a A coordinate
Returns: 1. The norm of the coordinate
function Coordinate:normalize()
Normalize a vector: Ensure that it has length 1. If the vector used to be the 0-vector, it gets replaced
by (1,0).
function Coordinate:normalized()
Normalized version of a vector: Like normalize, only the result is returned in a new vector.
Returns: 1. Normalized version of self
function Coordinate.boundingBox(array)
Compute a bounding box around an array of coordinates
Parameters: 1. array An array of coordinates
Returns: 1. min_x The minimum x value of the bounding box of the array
Returns: 1. min_y The minimum y value
Returns: 1. max_x
Returns: 1. max_y
Returns: 1. center_x The center of the bounding box
Returns: 1. center_y
Lua table Path (declared in pgf.gd.model.Path)
A Path models a path in the plane.
Following the PostScript/pdf/svg convention, a path consists of a series of path segments, each of
which can be closed or not. Each path segement, in turn, consists of a series of Bézier curvers and
straight line segments; see Section 14 for an introduction to paths in general.
A Path object is a table whose array part stores Coordinate objects, strings, and functions that
describe the path of the edge. The following strings are allowed in this array:
• "moveto" The line’s path should stop at the current position and then start anew at the next
coordinate in the array.
• "lineto" The line should continue from the current position to the next coordinate in the array.
• "curveto" The line should continue form the current position with a Bézier curve that is specified
bz the next three Coordinate objects (in the usual manner).
461
• "closepath" The line’s path should be “closed” in the sense that the current subpath that was
started with the most recent moveto operation should now form a closed curve.
Instead of a Coordinate, a Path may also contain a function. In this case, the function, when called,
must return the Coordinate that is “meant” by the position. This allows algorithms to add coordinates
to a path that are still not fixed at the moment they are added to the path.
Alphabetical method summary:
function Path.new (initial)
function Path:appendArcTo (target,radius_or_center,clockwise,trans)
function Path:appendArc (start_angle,end_angle,radius,trans)
function Path:appendClosepath ()
function Path:appendCurveto (a,b,c,d,e,f)
function Path:appendLineto (x,y)
function Path:appendMoveto (x,y)
function Path:boundingBox ()
function Path:clear ()
function Path:clone ()
function Path:coordinates ()
function Path:cutAtBeginning (index, time)
function Path:cutAtEnd (index, time)
function Path:intersectionsWith (path)
function Path:makeRigid ()
function Path:pad (padding)
function Path:reversed ()
function Path:shiftByCoordinate (x)
function Path:shift (x,y)
function Path:transform (t)
function Path.new(initial)
Creates an empty path.
Parameters: 1. initial A table containing an array of strings and coordinates that constitute the
path. Coordinates may be given as tables or as a pair of numbers. In this case, each pair of numbers is
converted into one coordinate. If omitted, a new empty path is created.
Returns: 1. A empty Path
function Path:clone()
Creates a copy of a path.
Returns: 1. A copy of the path
function Path:reversed()
Returns the path in reverse order.
Returns: 1. A copy of the reversed path
function Path:transform(t)
Transform all points on a path.
Parameters:
1. t A transformation, see pgf.gd.lib.Transform. It is applied to all Coordinate
objects on the path.
function Path:shift(x,y)
Shift all points on a path.
Parameters: 1. x An x-shift 2. y A y-shift
function Path:shiftByCoordinate(x)
Shift by all points on a path.
Parameters: 1. x A coordinate
462
function Path:clear()
Makes the path empty.
function Path:appendMoveto(x,y)
Appends a moveto to the path.
Parameters: 1. x A Coordinate or function or, if the y parameter is not nil, a number that is the
x-part of a coordiante . 2. y The y-part of the coordinate.
function Path:appendLineto(x,y)
Appends a lineto to the path.
Parameters: 1. x A Coordinate or function, if the y parameter is not nil, a number that is the
x-part of a coordiante . 2. y The y-part of the coordinate.
function Path:appendClosepath()
Appends a closepath to the path.
function Path:appendCurveto(a,b,c,d,e,f)
Appends a curveto to the path. There can be either three coordinates (or functions) as parameters (the
two support points and the target) or six numbers, where two consecutive numbers form a Coordinate.
Which case is meant is detected by the presence of a sixth non-nil parameter.
function Path:makeRigid()
Makes a path “rigid,” meaning that all coordinates that are only given as functions are replaced by the
values these functions yield.
function Path:coordinates()
Returns an array of all coordinates that are present in a path. This means, essentially, that all strings
are filtered out.
Returns: 1. An array of all coordinate objects on the path.
function Path:boundingBox()
Returns a bounding box of the path. This will not necessarily be the minimal bounding box in case the
path contains curves because, then, the support points of the curve are used for the computation rather
than the actual boinding box of the path.
If the path contains no coordinates, all return values are 0.
Returns: 1. min_x The minimum x value of the bounding box of the path
Returns: 1. min_y The minimum y value
Returns: 1. max_x
Returns: 1. max_y
Returns: 1. center_x The center of the bounding box
Returns: 1. center_y
function Path:intersectionsWith(path)
Computes all intersections of a path with another path and returns them as an array of coordinates.
The intersections will be sorted “along the path self.” The implementation uses a divide-and-conquer
approach that should be reasonably fast in practice.
Parameters: 1. path Another path
Returns: 1. Array of all intersections of path with self in the order they appear on self. Each entry
of this array is a table with the following fields:
• index The index of the segment in self where the intersection occurs.
• time The “time” at which a point travelling along the segment from its start point to its end point.
• point The point itself.
function Path:cutAtBeginning(index, time)
463
Shorten a path at the beginning. We are given the index of a segment inside the path as well as a
point in time along this segment. The path is now shortened so that everything before this segment
and everything in the segment before the given time is removed from the path.
Parameters: 1. index The index of a path segment. 2. time A time along the specified path segment.
function Path:cutAtEnd(index, time)
Shorten a path at the end. This method works like cutAtBeginning, only the path is cut at the end.
Parameters: 1. index The index of a path segment. 2. time A time along the specified path segment.
function Path:pad(padding)
“Pads” the path. The idea is the following: Suppose we stroke the path with a pen whose width is twice
the value padding. The outer edge of this stroked drawing is now a path by itself. The path will be a
bit longer and “larger.” The present function tries to compute an approximation to this resulting path.
The algorithm used to compute the enlarged part does not necessarily compute the precise new path.
It should work correctly for polyline paths, but not for curved paths.
Parameters: 1. padding A padding distance.
Returns: 1. The padded path.
function Path:appendArc(start_angle,end_angle,radius,trans)
Appends an arc (as in the sense of “a part of the circumference of a circle”) to the path. You may
optionally provide a transformation matrix, which will be applied to the arc. In detail, the following
happens: We first invert the transformation and apply it to the start point. Then we compute the arc
“normally”, as if no transformation matrix were present. Then we apply the transformation matrix to
all computed points.
Parameters:
1. start_angle The start angle of the arc. Must be specified in degrees.
2. end_angle the end angle of the arc. 3. radius The radius of the circle on which this arc lies.
4. trans A transformation matrix. If nil, the identity matrix will be assumed.
function Path:appendArcTo(target,radius_or_center,clockwise,trans)
Appends a clockwise arc (as in the sense of “a part of the circumference of a circle”) to the path such
that it ends at a given point. If a transformation matrix is given, both start and end point are first
transformed according to the inverted transformation, then the arc is computed and then transformed
back.
Parameters: 1. target The point where the arc should end. 2. radius_or_center If a number, it
is the radius of the circle on which this arc lies. If it is a Coordinate, this is the center of the circle.
3. clockwise If true, the arc will be clockwise. Otherwise (the default, if nothing or nil is given),
the arc will be counter clockise. 4. trans A transformation matrix. If missing, the identity matrix is
assumed.
Lua table Transform (declared in pgf.gd.lib.Transform)
The Transform table provides a set of static methods for creating and handling canvas transformation
matrices. Such a matrix is actually just an array of six numbers. The idea is that “applying” an array
a, b, c, d, e, f a vector (x, y) will yield the new vector (ax + by + e, cx + dy + f ). For details on how
such matrices work, see Section 103.2.1
Alphabetical method summary:
function Transform.concat (a,b)
function Transform.invert (t)
function Transform.new_rotation (angle)
function Transform.new_scaling (x_scale, y_scale)
function Transform.new_shift (x,y)
function Transform.new (a,b,c,d,x,y)
function Transform.new(a,b,c,d,x,y)
Creates a new transformation array.
464
Parameters: 1. a First component 2. b Second component
component 5. x The x shift 6. y The y shift
3. c Third component
4. d Fourth
Returns: 1. A transformation object.
function Transform.new_shift(x,y)
Creates a new transformation object that represents a shift.
Parameters: 1. x An x-shift 2. y A y-shift
Returns: 1. A transformation object
function Transform.new_rotation(angle)
Creates a new transformation object that represents a rotation.
Parameters: 1. angle An angle
Returns: 1. A transformation object
function Transform.new_scaling(x_scale, y_scale)
Creates a new transformation object that represents a scaling.
Parameters: 1. x The horizontal scaling 2. y The vertical scaling (if missing, the horizontal scaling is
used)
Returns: 1. A transformation object
function Transform.concat(a,b)
Concatenate two transformation matrices, returning the new one.
Parameters: 1. a The first transformation 2. b The second transformation
Returns: 1. The transformation representing first applying b and then applying a.
function Transform.invert(t)
Inverts a transformation matrix.
Parameters: 1. t The transformation.
Returns: 1. The inverted transformation
35.5.7
Options and Data Storages for Vertices, Arcs, and Digraphs
Many objects in the graph drawing system have an options table attached to them. These tables will
contain the different kinds options specified by the user for the object. For efficiency reasons, many objects
may share the same options table (since, more often than not, almost all objects have exactly the same
options table). For this reason, you cannot store anything in an options table, indeed, you should never
attemp to write anything into an options table. Instead, you should use a Storage.
Lua table Storage (declared in pgf.gd.lib.Storage)
A storage is an object that, as the name suggests, allows you to “store stuff concerning objects.” Basically,
it behaves like table having weak keys, which means that once the objects for which you “store stuff” go
out of scope, they are also removed from the storage. Also, you can specify that for each object of the
storage you store a table. In this case, there is no need to initialize this table for each object; rather,
when you write into such a table and it does not yet exist, it is created “on the fly”.
The typical way you use storages is best explained with the following example: Suppose you want to
write a depth-first search algorithm for a graph. This algorithm might wish to mark all nodes it has
visisted. It could just say v.marked = true, but this might clash with someone else also using the
marked key. The solution is to create a marked storage. The algorithm can first say
local marked = Storage.new()
and then say
marked[v] = true
to mark its objects. The marked storage object does not need to be created locally inside a function,
you can declare it as a local variable of the whole file; nevertheless, the entries for vertices no longer in
465
use get removed automatically. You can also make it a member variable of the algorithm class, which
allows you make the information about which objects are marked globally accessible.
Now suppose the algorithm would like to store even more stuff in the storage. For this, we might use a
table and can use the fact that a storage will automatically create a table when necessary:
local info = Storage.newTableStorage()
info[v].marked = true
info[v].foo
-- the "info[v]" table is
-- created automatically here
= "bar"
Again, once v goes out of scope, both it and the info table will removed.
Alphabetical method summary:
function Storage.newTableStorage ()
function Storage.new ()
function Storage.new()
Create a new storage object.
Returns: 1. A new Storage instance.
function Storage.newTableStorage()
Create a new storage object which will install a table for every entry automatilly.
Returns: 1. A new Storage instance.
35.5.8
Events
Lua table Event (declared in pgf.gd.lib.Event)
Events are used to communicate “interesting” events from the parser to the graph drawing algorithms.
As a syntactic description of some graph is being parsed, vertices, arcs, and a digraph object representing
this graph get constructed. However, even though syntactic annotations such as options for the vertices
and arcs are attached to them and can be accessed through the graph objects, some syntactic inforamtion
is neither represented in the digraph object nor in the vertices and the arcs. A typical example is a
“missing” node in a tree: Since it is missing, there is neither a vertex object nor arc objects representing
it. It is also not a global option of the graph.
For these reasons, in addition to the digraph object itself, additional information can be passed by a
parser to graph drawing algorithms through the means of events. Each Event consists of a kind field,
which is just some string, and a parameters field, which stores additional, kind-specific information. As
a graph is being parsed, a string of events is accumulated and is later on available through the events
field of the graph drawing scope.
The following events are created during the parsing process by the standard parsers of Tik Z:
node When a node of the input graph has been parsed and a Vertex object has been created for it, an
event with kind node is created. The parameter of this event is the just-created vertex.
The same kind of event is used to indicate “missing” nodes. In this case, the parameters field is
nil.
edge When an edge of the input graph has been parsed, an event is created of kind edge. The parameters
field will store an array with two entries: The first is the Arc object whose syntactic_edges field
stores the edge. The second is the index of the edge inside the syntactic_edges field.
begin Signals the beginning of a group, which will be ended with a corresponding end event later on.
The parameters field will indicate the kind of group. Currently, only the string "descendants"
is used as parameters, indicating the start of several nodes that are descendants of a given node.
This information can be used by algorithms for reconstructing the input structure of trees.
end Signals the end of a group begun by a begin event earlier on.
Field kind
A string representing the kind of the events.
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Field parameters
Kind-specific parameters.
Field index
A number that stores the events logical position in the sequence of events. The number need not
be an integer array index.
Alphabetical method summary:
function Event.new (values)
function Event.new(values)
Create a new event object
Parameters: 1. initial Initial fields of the new event.
Returns: 1. The new object
35.6
35.6.1
Graph Transformations
The Layout Pipeline
Lua table LayoutPipeline (declared in pgf.gd.control.LayoutPipeline)
This class controls the running of graph drawing algorithms on graphs. In particular, it performs preand posttransformations and also invokes the collapsing of sublayouts.
You do not call any of the methods of this class directly, the whole class is included only for documentation purposes.
Before an algorithm is applied, a number of transformations will have been applied, depending on the
algorithm’s preconditions field:
• connected
If this property is set for an algorithm (that is, in the declare statement for the algorithm the
predconditions field has the entry connected=true set), then the graph will be decomposed into
connected components. The algorithm is run on each component individually.
• tree
When set, the field spanning_tree of the algorithm will be set to a spanning tree of the graph.
This option implies connected.
• loop_free
When set, all loops (arcs from a vertex to itself) will have been removed when the algorithm runs.
• at_least_two_nodes
When explicitly set to false (this precondition is true by default), the algorithm will even be run
if there is only a single vertex in the graph.
Once the algorithm has run, the algorithm’s postconditions will be processed:
• upward_oriented
When set, the algorithm tells the layout pipeline that the graph has been laid out in a layered
manner with each layer going from left to right and layers at a whole going upwards (positive
y-coordinates). The graph will then be rotated and possibly swapped in accordance with the grow
key set by the user.
• fixed
When set, no rotational postprocessing will be done after the algorithm has run. Usually, a graph
is rotated to meet a user’s orient settings. However, when the algorithm has already “ideally”
rotated the graph, set this postcondition.
In addition to the above-described always-present and automatic transformations, users may also specify
additional pre- and posttransformations. This happens when users install additional algorithms in
appropriate phases. In detail, the following happens in order:
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1. If specified, the graph is decomposed into connected components and the following steps are applied
to each component individually.
2. All algorithms in the phase stack for the phase preprocessing are applied to the component.
These algorithms are run one after the other in the order they appear in the phase stack.
3. If necessary, the spanning tree is now computed and rotational information is gathered.
4. The single algorithm in phase main is called.
5. All algorithms in the phase stack for the phase edge routing are run.
6. All algorithms in the phase stack for phase postprocessing are run.
7. Edge syncing, orientation, and anchoring are applied.
If sublayouts are used, all of the above (except for anchoring) happens for each sublayout.
Alphabetical method summary:
function LayoutPipeline.anchor (graph, scope)
function LayoutPipeline.cutEdges (graph)
function LayoutPipeline.decompose (digraph)
function LayoutPipeline.orient (rotation_info, postconditions, graph, scope)
function LayoutPipeline.packComponents (syntactic_digraph, components)
function LayoutPipeline.prepareBoundingBoxes (rotation_info, adjusted_bb, graph, vertices)
function LayoutPipeline.prepareRotateAround (postconditions, graph)
function LayoutPipeline.anchor(graph, scope)
This function is called internally to perform the graph anchoring procedure described in Section 27.4.
These transformations are always performed.
Parameters: 1. graph A graph 2. scope The scope
function LayoutPipeline.prepareRotateAround(postconditions, graph)
This method tries to determine in which direction the graph is supposed to grow and in which direction
the algorithm will grow the graph. These two pieces of information togehter produce a necessary rotation
around some node. This rotation is returned in a table.
Note that this method does not actually cause a rotation to happen; this is left to other method.
Parameters: 1. postconditions The algorithm’s postconditions. 2. graph An undirected graph
Returns: 1. A table containing the computed information.
function LayoutPipeline.prepareBoundingBoxes(rotation_info, adjusted_bb, graph, vertices)
Compute growth-adjusted node sizes.
For each node of the graph, compute bounding box of the node that results when the node is rotated
so that it is in the correct orientation for what the algorithm assumes.
The “bounding box” actually consists of the fields
• sibling_pre,
• sibling_post,
• layer_pre, and
• layer_post,
which correspond to “min x”, “min y”, “min y”, and “max y” for a tree growing up.
The computation of the “bounding box” treats a centered circle in a special way, all other shapes are
currently treated like a rectangle.
Parameters:
1. rotation_info The table computed by the function prepareRotateAround
2. packing_storage A storage in which the computed distances are stored.
3. graph An graph
4. vertices An array of to-be-prepared vertices inside graph
function LayoutPipeline.orient(rotation_info, postconditions, graph, scope)
Performs a post-layout orientation of the graph by performing the steps documented in Section 27.5.
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Parameters: 1. rotation_info The info record computed by the function prepareRotateAround.
2. postconditions The algorithm’s postconditions. 3. graph A to-be-oriented graph. 4. scope The
graph drawing scope.
function LayoutPipeline.decompose(digraph)
This internal function is called to decompose a graph into its components. Whether or not this function
is called depends on whether the precondition connected is set for the algorithm class and whether the
componentwise key is used.
Parameters: 1. graph A to-be-decomposed graph
Returns: 1. An array of graph objects that represent the connected components of the graph.
function LayoutPipeline.packComponents(syntactic_digraph, components)
This internal function packs the components of a graph. See Section 27.7 for details.
Parameters: 1. graph The graph 2. components A list of components
function LayoutPipeline.cutEdges(graph)
Cut the edges. This function handles the “cutting” of edges. The idea is that every edge is a path going
from the center of the from node to the center of the target node. Now, we intersect this path with the
path of the start node and cut away everything before this intersection. Likewise, we intersect the path
with the head node and, again, cut away everything following the intersection.
These cuttings are not done if appropriate options are set.
35.6.2
Hints For Edge Routing
Lua table Hints (declared in pgf.gd.routing.Hints)
The Hints class provides a way for graph drawing algorithms to communicate certain possibilities
concerning the routing of edges to edge routing algorithms. This partly decouples the choice of the
vertex positioning algorithms from the choice of edge routing algorithm. For instance, for a simple
necklace routing, it is unclear whether the edges on the necklace should be routing “along the necklace”
or not. Thus, necklace routing algoirthms will “hint” that a necklace is present and only when the
necklace routing algorithm is selected will these hints lead to actual bending of edges.
For each kind of hint, there are methods in this class for creating the hints and other methods for
reading them. Hints are always local to the ugraph.
Alphabetical method summary:
function Hints.addNecklaceCircleHint (ugraph, necklace, center, clockwise)
function Hints.getNecklaceHints (ugraph)
function Hints.addNecklaceCircleHint(ugraph, necklace, center, clockwise)
Adds a necklace hint. In this case, the hint indicates that the given sequence of vertices lie on a circle.
The idea is that an algorithm may specify that in a given graph certain sequences of nodes form a
“necklace,” which is typically a circle. There may be more than one necklace inside a given graph. For
each necklace, whenever an arc connects subsequent nodes on the necklace, they get bend in such a way
that they lie follow the path of the necklace. If an arc lies on more than one necklace, the “last one
wins.”
Parameters: 1. ugraph The ugraph to which this hint is added 2. necklace The sequence of vertices
that form the necklace. If the necklace is closed, the last vertex must equal the first one. 3. center If
provided, must be Coordinate that specifies the center of the circle on which the vertices lie. If not
provided, the origin is assumed. 4. clockwise If true, the vertices are in clockwise order, otherwise
in counter-clockwise order.
function Hints.getNecklaceHints(ugraph)
Gets the necklace hints.
This function will return an array whose entries are necklace hints. Each entry in the array has a
necklace field, which is the field passed to the addNecklaceXxxx methods. For a circle necklace, the
center and clockwise fields will be set. (Other necklaces are not yet implemented.)
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Parameters: 1. ugraph The ugraph for which the necklace hints are requested.
Returns: 1. The array of necklaces as described above.
35.7
The Interface To Algorithms
Lua table InterfaceToAlgorithms (declared in pgf.gd.interface.InterfaceToAlgorithms)
This class provides the interface between the graph drawing system and algorithms. Another class,
InterfaceToDisplay, binds the display layers (like Tik Z or a graph drawing editor) to the graph
drawing system “from the other side”.
The functions declared here can be used by algorithms to communicate with the graph drawing system,
which will usually forward the “requests” of the algorithms to the display layers in some way. For
instance, when you declare a new parameter, this parameter will become available on the display layer.
Alphabetical method summary:
function InterfaceToAlgorithms.addHandler (test, handler)
function InterfaceToAlgorithms.createEdge (algorithm, tail, head, init)
function InterfaceToAlgorithms.createVertex (algorithm, init)
function InterfaceToAlgorithms.declare (t)
function InterfaceToAlgorithms.findVertexByName (name)
function InterfaceToAlgorithms.addHandler(test, handler)
Adds a handler for the declare function. The declare command is just a “dispatcher” to one of many
possible declaration functions. Which function is used, depends on which fields are present in the table
passed to declare. For each registered handler, we call the test function. If it returns neither nil nor
false, the handler field of this handler is called. If it returns true, the handler immediately finishes.
Otherwise, the next handler is tried.
function InterfaceToAlgorithms.declare(t)
This function is the “work-horse” for declaring things. It allows you to specify on the algorithmic
layer that a key “is available” for use on the display layer. There is just one function for handling all
declarations in order to make the declarations easy-to-use since you just need to import a single function:
local declare = require "pgf.gd.interface.InterfaceToAlgorithms".declare
You can now use declare it as follows: You pass it a table containing information about the to-bedeclared key. The table must have a field key whose value is unique and must be a string. If the value
of key is, say, "foo", the parameter can be set on the display layer such as, say, the Tik Z layer, using
/graph drawing/foo. Here is a typical example of how a declaration is done:
--declare {
key
= "electrical charge",
type
= "number",
initial = "1.0",
summary = "The “electrical charge” is a property...",
documentation = [[...]],
examples = [[...]]
}
Inlining Documentation. The three keys summary, documentation and examples are intended for
the display layer to give the users information about what the key does. The summary should be a string
that succinctly describes the option. This text will typically be displayed for instance as a “tool tip” or
in an option overview. The documentation optionally provides more information and should be typeset
using TEX. The examples can either be a single string or an array of strings. Each should be a Tik Z
example demonstrating how the key is used.
Note that you can take advantage of the Lua syntax of enclosing very long multi-line strings in [[ and
]]. As a bonus, if the summary, documentation, or an example starts and ends with a quote, these two
quotes will be stripped. This allows you to enclose the whole multi-line string (additionally) in quotes,
leading to better syntax highlighting in editors.
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External Documentation. It is sometimes more desirable to put the documentation of a key into
an external file. First, this makes the code leaner and, thus, faster to read (both for humans and for
computers). Second, for C code, it is quite inconvenient to have long strings inside a C file. In such
cases, you can use the documentation_in field:
--declare {
key
= "electrical charge",
type
= "number",
initial = "1.0",
documentation_in = "some_filename"
}
The some_filename must be the name of a Lua file that will be read “on demand,” that is, whenever
someone tries to access the documentation, summary, or examples field of the key, this file will be loaded
using require. The file should then use pgf.gd.doc to install the missing information in the keys.
The Use Field. When you declare a key, you can provide a use field. If present, you must set it to an
array of small tables which have two fields:
• key This is the name of another key or a function.
• value This is either a value (like a string or a number) or a function or nil.
Here is an example:
--declare {
key = "binary tree layout",
use = {
{ key = "minimum number of children", value = 2 },
{ key = "significant sep",
value = 12 },
{ key = "tree layout" }
},
summary = "The |binary tree layout| places node...",
documentation = ...,
examples = ...,
}
The effect of a use field is the following: Whenever the key is encountered on the option stack, the key
is first handled normally. Then, we iterate over all elements of the use array. For each element, we
perform the action as if the key of the array had been set explicitly to the value given by the value
field. If the value is a function, we pass a different value to the key, namely the result of applying the
function to the value originally passed to the original key. Here is a typical example:
--declare {
key = "level sep",
type = "length",
use = {
{ key = "level pre sep", value = function (v) return v/2 end },
{ key = "level post sep", value = function (v) return v/2 end }
},
summary = "..."
}
Just like the value, the key itself can also be a function. In this case, the to-be-used key is also computed
by applying the function to the value passed to the original key.
As mentioned at the beginning, declare is a work-horse that will call different internal functions depending on whether you declare a parameter key or a new algorithm or a collection kind. Which kind
of declaration is being done is detected by the presence of certain fields in the table passed to t. The
different kind of possible declarations are documented in the declare_... functions. Note that these
functions are internal and cannot be called from outside; you must use the declare function.
Parameters: 1. t A table contain the field key and other fields as described.
function declare_parameter(t)
This function is called by declare for “normal parameter keys,” which are all keys for which no special
field like algorithm or layer is declared. You write
471
--declare {
key
= "electrical charge",
type
= "number",
initial = "1.0",
summary = "The “electrical charge” is a property...",
documentation = [[...]],
examples = [[...]]
}
When an author writes my node[electrical charge=5-3] in the description of her graph, the object
vertex corresponding to the node my node will have a field options attached to it with
vertex.options["electrical charge"] == 2
The type field does not refer to Lua types. Rather, these types are sensible types for graph drawing
and they are mapped by the higher layers to Lua types. In detail, the following types are available:
• number A dimensionless number. Will be mapped to a normal Lua number. So, when the author
writes foo=5*2, the foo key of the options field of the corresponding object will be set to 10.0.
• length A “dimension” in the sense of TEX (a number with a dimension like cm attached to it). It
is the job of the display layer to map this to a number in “TEX points,” that is, to a multiple of
1/72.27th of an inch.
• string Some text. Will be mapped to a Lua string.
• canvas coordinate A position on the canvas. Will be mapped to a model.Coordinate.
• boolean A Boolean value.
• raw Some to-be-executed Lua text.
• direction Normally, an angle; however, the special values of down, up, left, right as well as the
directions north, north west, and so on are also legal on the display layer. All of them will be
mapped to a number. Furthermore, a vertical bar (|) will be mapped to -90 and a minus sign (-)
will be mapped to 0.
• hidden A key of this type “cannot be set,” that is, users cannot set this key at all. However
algorithms can still read this key and, through the use of alias, can use the key as a handle to
another key.
• user value The key stores a Lua user value (userdata). Such keys can only be set from C since
user values cannot be created in Lua (let alone in Tik Z).
If the type field is missing, it is automatically set to "string".
A parameter can have an initial value. This value will be used whenever the parameter has not been
set explicitly for an object.
A parameter can have a default value. This value will be used as the parameter value whenever the
parameter is explicitly set, but no value is provided. For a key of type "boolean", if no default is
provided, "true" will be used automatically.
A parameter can habe an alias field. This field must be set to the name of another key or to a function.
Whenever you access the current key and this key is not set, the alias key is tried instead. If it is set,
its value will be returned (if the alias key has itself an alias set, this is tried recursively). If the alias
is not set either and neither does it have an initial value, the initial value is used. Note that in case
the alias has its initial field set, the initial value of the current key will never be used.
The main purpose of the current key is to allow algorithms to introduce their own terminology for keys
while still having access to the standard keys. For instance, the OptimalHierarchyLayout class uses
the name layerDistance for what would be called level distance in the rest of the graph drawing
system. In this case, we can declare the layerDistance key as follows:
declare {
key
= "layerDistance",
type
= "length",
alias
= "level distance"
}
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Inside the algorithm, we can write ...options.layerDistance and will get the current value of the
level distance unless the layerDistance has been set explicitly. Indeed, we might set the type to
hidden to ensure that only the level distance can and must set to set the layerDistance.
Note that there is a difference between alias and the use field: Suppose we write
declare {
key
type
use
{ key
}
}
=
=
=
=
"layerDistance",
"length",
{
"level distance", value = lib.id }
Here, when you say layerDistance=1cm, the level distance itself will be modified.
level distance is set, however, the layerDistance will not be modified.
When the
If the alias is a function, it will be called with the option table as its parameter. You can thus say things
like
declare {
key
= "layerDistance",
type
= "length",
alias
= function (option)
return option["layer pre dist"] + option["layer post dist"]
end
}
As a special curtesy to C code, you can also set the key alias_function_string, which allows you to
put the function into a string that is read using loadstring.
(You cannot call this function directly, it is included for documentation purposes only.)
Parameters: 1. t The table originally passed to declare.
function declare_algorithm(t)
This function is called by declare for “algorithm keys.” These keys are normally used without a value
as in just \graph[tree layout], but you can optionally pass a value to them. In this case, this value
must be the name of a phase and the algorithm of this phase will be set (and not the default phase of
the key), see the description of phases below for details.
Algorithm keys are detected by the presence of the field algorithm in the table t passed to declare.
Here is an example of how it is used:
local ReingoldTilford1981 = {}
--declare {
key
= "tree layout",
algorithm = ReingoldTilford1981,
preconditions = {
connected = true,
tree
= true
},
postconditions = {
upward_oriented = true
},
summary = "The Reingold--Tilford method is...",
documentation = ...,
examples = ...,
}
function ReingoldTilford1981:run()
...
end
The algorithm field expects either a table or a string as value. If you provide a string, then require
will be applied to this string to obtain the table; however, this will happen only when the key is actually
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used for the first time. This means that you can declare (numerous) algorithms in a library without
these algorithms actually being loaded until they are needed.
Independently of how the table is obtained, it will be “upgraded” to a class by setting its __index field
and installing a static new function (which takes a table of initial values as argument). Both these
settings will only be done if they have not yet been performed.
Next, you can specify the fields preconditions and postconditions. The preconditions are a table that
tell the graph drawing engine what kind of graphs your algorithm expects. If the input graph is not of
this kind, it will be automatically transformed to meet this condition. Similarly, the postconditions tell
the engine about properties of your graph after the algorithm has run. Again, additional transformations
may be performed.
You can also specify the field phase. This tells the graph drawing engine which “phase” of the graph
drawing process your option applies to. Each time you select an algorithm later on through use of the
algorithm’s key, the algorithm for this phase will be set; algorithms of other phases will not be changed.
For instance, when an algorithm is part of the spanning tree computation, its phase will be "spanning
tree computation" and using its key does not change the main algorithm, but only the algorithm used
during the computation of a spanning tree for the current graph (in case this is needed by the main
algorithm). In case the phase field is missing, the phase main is used. Thus, when no phase field is
given, the key will change the main algorithm used to draw the graph.
Later on, the algorithm set for the current phase can be accessed through the special algorithm_phases
field of options tables. The algorithm_phases table will contain two fields for each phase for which
some algorithm has been set: One field is the name of the phase and its value will be the most recently
set algorithm (class) set for this phase. The other field is the name of the phase followed by " stack".
It will contain an array of all algorithm classes that have been set for this key with the most recently
at the end.
The following example shows the declaration of an algorithm that is the default for the phase "spanning
tree computation":
--declare {
key = "breadth first spanning tree",
algorithm = {
run =
function (self)
return SpanningTreeComputation.computeSpanningTree(self.ugraph, false, self.events)
end
},
phase = "spanning tree computation",
phase_default = true,
summary = ...
}
The algorithm is called as follows during a run of the main algorithms:
local graph = ... -- the graph object
local spanning_algorithm_class = graph.options.algorithm_phases["spanning tree computation"]
local spanning_algorithm =
spanning_algorithm_class.new{
ugraph = ugraph,
events = scope.events
}
local spanning_tree = spanning_algorithm:run()
If you set the phase_default field of t to true, the algorithm will be installed as the default algorithm
for the phase. This can be done only once per phase. Furthermore, for such a default algorithm the
algorithm key must be table, it may not be a string (in other words, all default algorithms are loaded
immediately). Accessing the algorithm_phases table for a phase for which no algorithm has been set
will result in the default algorithm and the phase stack will also contain this algorithm; otherwise the
phase stack will be empty.
(You cannot call this function directly, it is included for documentation purposes only.)
Parameters: 1. t The table originally passed to declare.
function declare_collection_kind(t)
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This function is called by declare for “collection kinds.” They are detected by the presence of the field
layer in the table t passed to declare. See the class Collection for details on what a collection and
a collection kind is.
The key field of the table t passed to this function is both the name of the to-be-declared collection
kind as well as the key that is used on the display layer to indicate that a node or edge belongs to a
collection.
The Display Layer. Let us first have a look at what happens on the display layer: A key t.key is
setup on the display layer that, when used inside a graph drawing scope, starts a new collection of the
specified kind. “Starts” means that all nodes and edges mentioned in the rest of the current option scope
will belong to a new collection of kind t.key.
declare { key = "hyper", layer = 1 }
you can say on the Tik Z layer
\graph {
a, b, c, d;
{ [hyper] a, b, c }
{ [hyper] b, c, d }
};
In this case, the nodes a, b, c will belong to a collection of kind hyper. The nodes b, c, and d will (also)
belong to another collection of the same kind hyper. You can nest collections; in this case, nodes will
belong to several collections.
The effect of declaring a collection kind on the algorithm layer it, first of all, that scope.collections
will have a field named by the collection kind. This field will store an array that contains all collections
that were declared as part of the graph. For instance, collections.hyper will contain all hyperedges,
each of which is a table with the following fields: The vertices and edges fields each contain arrays
of all objects being part of the collection. The sub field is an array of “subcollections,” that is, all
collections that were started inside another collection. (For the collection kinds hyper and same layer
this makes no sense, but subgraphs could, for instance, be nested.)
Rendering of Collections. For some kinds of collections, it makes sense to render them, but only after
the graph drawing algorithm has run. For this purpose, the binding layer will use a callback for each
collection kind and each collection, see the Binding class for details. Suppose, for instance, you would
like hyperedges to be rendered. In this case, a graph drawing algorithm should iterate over all collections
of type hyper and compute some hints on how to render the hyperedge and store this information in
the generated_options table of the hyperedge. Then, the binding layer will ask the dislay layer to run
some some code that is able to read key–value pairs passed to it (which are the key–value pairs of the
generated_options table) and use this information to nicely draw the hyperedge.
The number t.layer determines in which order the different collection kinds are rendered.
The last parameter, the layer number, is used to specify the order in which the different collection kinds
are rendered. The higher the number, the later the collection will be rendered. Thus, if there is a
collection kind with layer number 10 and another with layer number 20, all collections of the first kind
will be rendered first, followed by all collections of the second kind.
Collections whose layer kinds are non-negative get rendered after the nodes and edges have already
been rendered. In contrast, collections with a negative layer number get shown “below” the nodes and
edges.
(You cannot call this function directly, it is included for documentation purposes only.)
Parameters: 1. t The table originally passed to declare.
function InterfaceToAlgorithms.findVertexByName(name)
Finds a node by its name. This method should be used by algorithms for which a node name is specified
in some option and, thus, needs to be converted to a vertex object during a run of the algorithm.
Parameters: 1. name A node name
Returns: 1. The vertex of the given name in the syntactic digraph or nil.
function InterfaceToAlgorithms.createVertex(algorithm, init)
475
Generate a new vertex in the syntactic digraph. Calling this method allows algorithms to create vertices
that are not present in the original input graph. Using the graph drawing coroutine, this function will
pass back control to the display layer in order to render the vertex and, thereby, create precise size
information about it.
Note that creating new vertices in the syntactic digraph while the algorithm is already running is a bit at
odds with the notion of treating graph drawing as a series of graph transformations: For instance, when
a new vertex is created, the graph will (at least temporarily) no longer be connected; even though an
algorithm may have requested that it should only be fed connected graphs. Likewise, more complicated
requirements like insisting on the graph being a tree also cannot be met.
For these reasons, the following happens, when a new vertex is created using the function:
1. The vertex is added to the syntactic digraph.
2. It is added to all layouts on the current layout stack. When a graph drawing algorithm is run, it is
not necessarily run on the original syntactic digraph. Rather, a sequence / stack of nested layouts
may currently be processed and the vertex is added to all of them.
3. The vertex is added to both the digraph and the ugraph of the current algorithm.
Parameters:
1. algorithm An algorithm for whose syntactic digraph the node should be added
2. init A table of initial values for the node that is passed to Binding:createVertex, see that function
for details.
Returns: 1. The newly created node
function InterfaceToAlgorithms.createEdge(algorithm, tail, head, init)
Generate a new edge in the syntactic digraph. This method is quite similar to createVertex and has
the same effects with respect to the edge: The edge is added to the syntactic digraph and also to all
layouts on the layout stack. Forthermore, appropriate edges are added to the digraph and the ugraph
of the algorithm currently running.
Parameters:
1. algorithm An algorithm for whose syntactic digraph the node should be added
2. tail A syntactic tail vertex 3. head A syntactic head vertex 4. init A table of initial values for
the edge.
The following fields are useful for init:
• init.direction If present, a direction for the edge. Defaults to "–".
• init.options If present, some options for the edge.
• init.generated_options A table that is passed back to the display layer as a list of key-value
pairs in the syntax of declare_parameter.
35.8
Examples of Implementations of Graph Drawing Algorithms
Graph Drawing Library examples
\usegdlibrary{examples} % LATEX and plain TEX
\usegdlibrary[examples] % ConTEXt
This package presents some examples of how different aspects of the graph drawing engine can be used.
In particular, the algorithms of this package are not really meant to be used to layout graphs (although
they can be used, in principle); rather you are invited to have a look at their implementation and to
adapt them to your needs.
35.8.1
The “Hello World” of Graph Drawing
/graph drawing/simple demo layout=hstringi
This algorithm is the “Hello World” of graph drawing.
The algorithm arranges nodes in a circle (without paying heed to the sizes of the nodes or to the edges).
In order to “really” layout nodes in a circle, use simple necklace layout; the present layout is only
intended to demonstrate how much (or little) is needed to implement a graph drawing algorithm.
476
-- File pgf.gd.examples.SimpleDemo
local declare = require "pgf.gd.interface.InterfaceToAlgorithms".declare
declare {
key = "simple demo layout",
algorithm = {
run =
function (self)
local g = self.digraph
local alpha = (2 * math.pi) / #g.vertices
for i,vertex in ipairs(g.vertices) do
local radius = vertex.options[’radius’] or g.options[’radius’]
vertex.pos.x = radius * math.cos(i * alpha)
vertex.pos.y = radius * math.sin(i * alpha)
end
end
},
summary = "This algorithm is the ’Hello World’ of graph drawing.",
documentation = [["
This algorithm arranges nodes in a circle ...
"]]
}
On the display layer (Tik Z, that is) the algorithm can now immediately be employed; you just need to
say \usegdlibrary{examples.SimpleDemo} at the beginning somewhere.
35.8.2
How To Generate Edges Inside an Algorithm
/graph drawing/simple edge demo layout=hstringi
This algorithm shows how edges can be created by an algorithm.
For its job, the algorithm uses the function createEdge, which can be called during the run of the
algorithm to create edges in the syntactic graph. The algorithm first does exactly the same as the
simple demo layout, then it creates an edge for every node where the new edge to option is set. You
will see in the code how this option is declared and how we use it to look up a vertex in the graph by
its name.
\tikz [simple edge demo layout]
\graph [radius=2cm] {
a, b, c, d, e, f;
f
e
a
d
b
e -> [red] f; % normal edge
% Edges generated by the algorithm:
a[new edge to=b];
b[new edge to=d];
c[new edge to=f];
};
c
And the algorithm:
-- File pgf.gd.examples.SimpleEdgeDemo
-- Imports
local InterfaceToAlgorithms = require "pgf.gd.interface.InterfaceToAlgorithms"
local declare
= InterfaceToAlgorithms.declare
-- The class object
local SimpleEdgeDemo = {}
declare {
key = "simple edge demo layout",
algorithm = SimpleEdgeDemo,
summary = "This algorithm shows...",
}
Next comes the declaration of the new option new edge to:
477
declare {
key = "new edge to",
type = "string",
summary = "This option takes the name of a vertex..."
}
Finally, the algorithm’s code:
function SimpleEdgeDemo:run()
-- As in a SimpleDemo:
...
-- Now add some edges:
for _,tail in ipairs(g.vertices) do
local name = tail.options[’new edge to’]
if name then
local node = InterfaceToAlgorithms.findVertexByName(name)
if node and self.digraph:contains(node) then
InterfaceToAlgorithms.createEdge (self, tail, node)
end
end
end
end
/graph drawing/new edge to=hstringi
This option takes the name of a vertex. An edge leading to this vertex is added to the syntactic digraph.
35.8.3
How To Generate Nodes Inside an Algorithm
/graph drawing/simple Huffman layout=hstringi
This algorithm demonstrates how an algorithm can generate new nodes.
The input graph should just consist of some nodes (without edges) and each node should have a
probability key set. The nodes will then be arranged in a line (as siblings) and a Huffman tree
will be constructed “above” these nodes. For the construction of the Huffman tree, new nodes are
created and connected.
0.5 0.12 0.2 0.1 0.11
a
c
e
b
d
0 1
0 1
0
0
1
\tikz \graph [simple Huffman layout,
level distance=7mm, sibling distance=8mm, grow’=up]
{
a ["0.5", probability=0.5],
b ["0.12", probability=0.12],
c ["0.2", probability=0.2],
d ["0.1", probability=0.1],
e ["0.11", probability=0.11]
};
1
The file starts with some setups and declarations:
478
-- File pgf.gd.examples.SimpleHuffman
local declare = require "pgf.gd.interface.InterfaceToAlgorithms".declare
-- The class
local SimpleHuffman = {}
declare {
key
= "simple Huffman layout",
algorithm
= SimpleHuffman,
postconditions = { upward_oriented = true
summary = "..."
}
}
declare {
key = "probability",
type = "number",
initial = "1",
summary = "..."
}
-- Import
local layered = require "pgf.gd.layered"
local InterfaceToAlgorithms = require "pgf.gd.interface.InterfaceToAlgorithms"
local Storage = require "pgf.gd.lib.Storage"
local probability = Storage.new()
local layer
= Storage.new()
function SimpleHuffman:run()
-- Construct a Huffman tree on top of the vertices...
Next comes a setup, where we create the working list of vertices that changes as the Huffman coding
method proceeds:
-- Shorthand
local function prop (v)
return probability[v] or v.options[’probability’]
end
-- Copy the vertex table, since we are going to modify it:
local vertices = {}
for i,v in ipairs(self.ugraph.vertices) do
vertices[i] = v
end
The initial vertices are arranged in a line on the last layer. The function ideal_sibling_distance
takes care of the rather complicated handling of the (possibly rotated) bounding boxes and separations.
The props and layer are tables used by algorithms to “store stuff” at a vertex or at an arc. The table
will be accessed by arrange_layers_by_baselines to determine the ideal vertical placements.
-- Now, arrange the nodes in a line:
vertices [1].pos.x = 0
layer[ vertices [1] ] = #vertices
for i=2,#vertices do
local d = layered.ideal_sibling_distance(self.adjusted_bb, self.ugraph, vertices[i-1], vertices[i])
vertices [i].pos.x = vertices[i-1].pos.x + d
layer[ vertices [i] ] = #vertices
end
Now comes the actual Huffman algorithm: Always find the vertices with a minimal probability. . .
479
-- Now, do the Huffman thing...
while #vertices > 1 do
-- Find two minimum probabilities
local min1, min2
for i=1,#vertices do
if not min1 or prop(vertices[i]) < prop(vertices[min1]) then
min2 = min1
min1 = i
elseif not min2 or prop(vertices[i]) < prop(vertices[min2]) then
min2 = i
end
end
. . . and connect them with a new node. This new node gets the option HuffmanNode. It is now the job
of the higher layers to map this option to something “nice”.
-- Create new node:
local p = prop(vertices[min1]) + prop(vertices[min2])
local v = InterfaceToAlgorithms.createVertex(self, { generated_options = {{key="HuffmanNode"}}})
probability[v] = p
layer[v] = #vertices-1
v.pos.x = (vertices[min1].pos.x + vertices[min2].pos.x)/2
vertices[#vertices + 1] = v
InterfaceToAlgorithms.createEdge (self, v, vertices[min1],
{generated_options = {{key="HuffmanLabel", value = "0"}}})
InterfaceToAlgorithms.createEdge (self, v, vertices[min2],
{generated_options = {{key="HuffmanLabel", value = "1"}}})
table.remove(vertices, math.max(min1, min2))
table.remove(vertices, math.min(min1, min2))
end
Ok, we are mainly done now. Finish by computing vertical placements and do formal cleanup.
layered.arrange_layers_by_baselines(layers, self.adjusted_bb, self.ugraph)
end
In order to use the class, we have to make sure that, on the display layer, the options HuffmanLabel
and HuffmanNode are defined. This is done by adding, for instance, the following to Tik Z:
\pgfkeys{
/graph drawing/HuffmanLabel/.style={
/tikz/edge node={node[fill=white,font=\footnotesize,inner sep=1pt]{#1}}
},
/graph drawing/HuffmanNode/.style={
/tikz/.cd,circle,inner sep=0pt,outer sep=0pt,draw,minimum size=3pt
}
}
/graph drawing/probability=hnumber i
(initially 1)
The probability parameter. It is used by the Huffman algorithm to group nodes.
35.9
Support Libraries
The present section lists a number of general-purpose libraries that are used by different algorithms.
35.9.1
Basic Functions
Lua table pgf (declared in pgf)
The pgf namespace lies in the global namespace. It is the only global table defined by pgf. The whole
graph drawing system, in turn, lies in the table pgf.gd.
function pgf.debug(...)
Writes debug info on the TEX output, separating the parameters by spaces. The debug information will
include a complete traceback of the stack, allowing you to see “where you are” inside the Lua program.
480
Note that this function resides directly in the pgf table. The reason for this is that you can “always use
it” since pgf is always available in the global name space.
Parameters: 1. ... List of parameters to write to the TEX output.
Lua table lib (declared in pgf.gd.lib)
Basic library functions
Alphabetical method summary:
function lib.class (t)
function lib.copy (source, target)
function lib.find_min (array, f)
function lib.find (array, test)
function lib.icopy (source, target)
function lib.id (...)
function lib.imap (source, fun, new)
function lib.lookup_option (name, ...)
function lib.map (source, fun)
function lib.ondemand (filename, table, name)
function lib.random_permutation (n)
function lib.find(array, test)
Finds the first value in the array for which test is true.
Parameters: 1. array An array to search in. 2. test A function that is applied to each element of
the array together with the index of the element and the whole table.
Returns: 1. The value of the first value where the test is true.
Returns: 1. The index of the first value where the test is true.
Returns: 1. The function value of the first value where the test is true (only returned if test is a
function).
function lib.find_min(array, f)
Finds the first value in the array for which a function returns a minimal value
Parameters: 1. array An array to search in. 2. f A function that is applied to each element of
the array together with the index of the element and the whole table. It should return an integer and,
possibly, a value.
Among all elements for which a non-nil integer is returned, let i by the index of the element where this
integer is minimal.
Returns: 1. array[i]
Returns: 1. i
Returns: 1. The return value(s) of the function at array[i].
function lib.copy(source, target)
Copies a table while preserving its metatable.
Parameters: 1. source The table to copy. 2. target The table to which values are to be copied or
nil if a new table is to be allocated.
Returns: 1. The target table or a newly allocated table containing all keys and values of the source
table.
function lib.icopy(source, target)
Copies an array while preserving its metatable.
Parameters: 1. source The array to copy. 2. target The array to which values are to be copied or
nil if a new table is to be allocated. The elements of the source array will be added at the end.
Returns: 1. The target table or a newly allocated table containing all keys and values of the source
table.
481
function lib.map(source, fun)
Apply a function to all pairs of a table, resulting in a new table.
Parameters: 1. source The table. 2. fun A function taking two arguments (val and key, in that
order). Should return two values (a new_val and a new_key). This pair will be inserted into the new
table. If, however, new_key is nil, the new_value will be inserted at the position key. This means, in
particular, that if the fun takes only a single argument and returns only a single argument, you have a
“classical” value mapper. Also note that if new_value is nil, the value is removed from the table.
Returns: 1. The new table.
function lib.imap(source, fun, new)
Apply a function to all elements of an array, resulting in a new array.
Parameters: 1. source The array. 2. fun A function taking two arguments (val and i, the current
index). This function is applied to all elements of the array. The result of this function is placed at the
end of a new array, expect when the function returns nil, in which case the element is skipped. If this
function is not provided (is nil), the identity function is used. 3. new The target array (if nil, a new
array is create).
local a = lib.imap(array, function(v) if some_test(v) then return v end end)
The above code is a filter that will remove all elements from the array that do not pass some_test.
lib.imap(a, lib.id, b)
The above code has the same effect as lib.icopy(a,b).
Returns: 1. The new array
function lib.random_permutation(n)
Generate a random permutation of the numbers 1 to n in time O(n). Knuth’s shuffle is used for this.
Parameters: 1. n The desired size of the table
Returns: 1. A random permutation
function lib.id(...)
The identity function, so you can write lib.id instead of function (x) return x end.
function lib.lookup_option(name, ...)
Tries to find an option in different objects that have an options field.
This function iterates over all objects given as parameters. In each, it tries to find out whether the
options field of the object contains the option name and, if so, returns the value. The important point
is that checking whether the option table of an object contains the name field is done using rawget for
all but the last parameter. This means that when you write
lib.lookup_option("foo", vertex, graph)
and if /graph drawin/foo has an inital value set, if the parameter is not explicitly set in a vertex, you
will get the value set for the graph or, if it is not set there either, the initial value. In contrast, if you
write
vertex.options["foo"] or graph.options["foo"]
what happens is that the first access to .options will always return something when an initial parameter
has been set for the option foo.
Parameters: 1. name The name of the options 2. ... Any number of objects. Each must have an
options field.
Returns: 1. The found option
function lib.class(t)
Turns a table t into a class in the sense of object oriented programming. In detail, this means that t
is augmented by a new function, which takes an optional table of initial values and which outputs a
482
new table whose metatable is the class. The new function will call the function constructor if it exsist.
Furthermore, the class object’s __index is set to itself and its meta table is set to the base_class field
of the table. If t is nil, a new table is created.
Here is a typical usage of this function:
local Point = lib.class {}
function Point:length()
return math.sqrt(self.x*self.x + self.y*self.y)
end
local p = Point.new { x = 5, y = 6 }
print(p:length())
We can subclass this as follows:
local Point3D = lib.class { base_class = Point }
function Point3D:length()
local l = Point.length(self) -- Call base class’s function
return math.sqrt(l*l + self.z*self.zdy)
end
local p = Point3D.new { x = 5, y = 6, z = 6 }
print(p:length())
Parameters: 1. t A table that gets augmented to a class. If nil, a new table is created.
Returns: 1. The augmented table.
function lib.ondemand(filename, table, name)
Returns a method that is loaded only on demand for a class.
The idea behind this function is that you may have a class (or just a table) for which some methods are
needed only seldomly. In this case, you can put these methods in a separate file and then use ondemand
to indicate that the methods are found in a another file.
-- File Foo.lua
local Foo = {}
function Foo.bar () ... end
function Foo.bar2 () ... end
Foo.bar3 = lib.ondemand("Foo_extra", Foo, "bar3")
Foo.bar4 = lib.ondemand("Foo_extra", Foo, "bar4")
return Foo
-- Foo_extra.lua
local Foo = require "Foo"
function Foo.bar3 () ... end
function Foo.bar4 () ... end
Parameters: 1. filename The name of the file when extra methods are located. 2. table The table
for which the missing functions should be loaded when they are accessed. 3. method The name of the
method.
Returns: 1. A function that, when called, loads the filename using require and, then, forwards the
call to the method.
35.9.2
Lookup Tables
Lua table LookupTable (declared in pgf.gd.lib.LookupTable)
This table provides two utility functions for managing “lookup tables.” Such a table is a mixture of an
array and a hashtable: It stores (only) tables. Each table is stored once in a normal array position.
Additionally, the lookup table is also indexed at the position of the table (used as a key) and this
position is set to true. This means that you can test whether a table t is in the lookup table l simply
by testing whether l[t] is true.
483
Alphabetical method summary:
function LookupTable.addOne (l, e)
function LookupTable.add (l, array)
function LookupTable.remove (l, array)
function LookupTable.add(l, array)
Add all elements in the array to a lookup table. If an element of the array is already present in the
table, it will not be added again.
This operation takes time O(\verb!array!).
Parameters: 1. l Lookup table 2. array An array of to-be-added tables.
function LookupTable.addOne(l, e)
Add one element to a lookup table. If it is already present in the table, it will not be added again.
This operation takes time O(1).
Parameters: 1. l Lookup table 2. e The to-be-added element.
function LookupTable.remove(l, array)
Remove tables from a lookup table.
Note that this operation is pretty expensive insofar as it will always cost a traversal of the whole lookup
table. However, this is also the maximum cost, even when a lot of entries need to be deleted. Thus, it
is much better to “pool” multiple remove operations in a single one.
This operation takes time O(max{\verb!array!, \verb!l!}).
Parameters: 1. l Lookup table 2. t An array of to-be-removed tables.
35.9.3
Computing Distances in Graphs
Still needs to be ported to digraph classes!
35.9.4
Priority Queues
Lua table PriorityQueue (declared in pgf.gd.lib.PriorityQueue)
A PriorityQueue supports operations for quickly finding the minimum from a set of elements
Its implementation is based on (simplified) Fibonacci heaps.
Alphabetical method summary:
function PriorityQueue.new ()
function PriorityQueue:dequeue ()
function PriorityQueue:enqueue (value, priority)
function PriorityQueue:isEmpty ()
function PriorityQueue:updatePriority (value, priority)
function PriorityQueue.new()
Creates a new priority queue
Returns: 1. The newly created queue
function PriorityQueue:enqueue(value, priority)
Add an element with a certain priority to the queue
Parameters: 1. value An object 2. priority Its priority
function PriorityQueue:dequeue()
Removes the element with the minimum priority from the queue
Returns: 1. The element with the minimum priority
function PriorityQueue:updatePriority(value, priority)
Lower the priority of an element of a queue
Parameters:
priority
1. value An object
2. priority A new priority, which must be lower than the old
484
function PriorityQueue:isEmpty()
Tests, whether the queue is empty
Returns: 1. True, if the queue is empty
485
36
Writing Graph Drawing Algorithms in C
by Till Tantau
In the present section we have a look at how graph drawing algorithms written in the C programming
language (or in C++) can be used in the graph drawing framework.
Warning: Graph drawing algorithms written in C can be incredibly fast if you use the facilities
of C correctly. However, C code is much less portable than Lua code in the sense that it has to
be compiled for the specific platform used by the user and that it has to be linked dynamically
during a run of the TEX program. All of this in possible (and works, as demonstrated by the
linking of the ogdf framework), but it is much harder to get right than writing Lua code.
Bottom line, you really should be using this method only if it is really necessary (namely, when
Lua code is simply not fast enough).
In the following, I first explain how the link between TEX and C code works, in general. Then, in the
subsequent sections, we go over the different kinds of programming languages and frameworks for which
there is direct support for such a link.
36.1
How C and TEX Communicate
In order to use C code for graph drawing algorithms during a run of the TEX program, there is no need to
build a new version of TEX. Rather, it is possible that C code is linked into the TEX executable at runtime.
This is made possible by the fact that Lua (which part of LuaTEX. . . ) is able to link C libraries at runtime
– provided a strict regime of rules is adhered to:
1. When you say require in Lua, it will normally look for a .lua file; but it will also try to find a .so
file (a shared C library) as a fallback.
2. If it finds such a shared library, Lua(TEX) will try to link this library dynamically at runtime.
3. Inside the library, there must be a function (called an entry point) with a special name (it must start
with luaopen_ and it must otherwise be the path and name of the library with slashes replaced by
underscores).
4. This function gets called by Lua, once. Its job is to setup the library so that it can be used by Lua.
Mainly, this means that certain C functions get registered in such a way that Lua can call them.
5. At this point, control returns to Lua and, now, certain functions have become available on the Lua
layer that, when called, actually invoke the C code of our linked library.
For each of the above points, there are some bells and whistles:
1. LuaTEX looks at slightly inconvenient places for shared libraries: By default, (currently, 2013) it looks
in a lib subdirectory of the directory containing the LuaTEX executable. The logic behind is that the
shared libraries depend on the specific architecture of the executable. Thus, unlike normal Lua files,
the library needs to be installed “far away” from the actual package of which it is part.
2. Certain vesions of LuaTEX have a broken handling of filenames of libraries written in C. The TL2013
version of LuaTEX, for instance, crashes when the filename of a shared library does not contain the
complete path (while this works for normal file). Hopefully, this, too, will be fixed in future versions.
3. On certain platforms, the support for dynamic linking against LuaTEX is broken since the symbol table
of the Lua library has been stripped away. Hopefully, this will be fixed soon; in the meantime, a highly
fragile workaround is to link in another copy of the Lua library.
4. The entry point that is called by Lua requires a certain signature (it takes a Lua state as its only
parameter) and must return the number of objects it returns on the Lua stack.
5. The registration process of C functions is somewhat tricky and changes from Lua version to Lua version.
6. C functions that get called by Lua must follow all sorts of tricky rules in order to communicate with
Lua correctly.
486
Despite the above obstacles, one can use graph drawing algorithms written in C inside Lua, in principle,
as follows: One loads an appropriately prepared and located C library using require and this library uses
commands like declare to register its own functions into the graph drawing system so that when the run
method is called, a C functions gets called instead.
Unfortunately, the above approach is extremely tedious and error-prone and it is “no fun” to access Lua
data structures (such as the syntactic digraph) from C. For this reason, I have written some libraries that
encapsulate (as much as possible) of this communication between C and Lua. Indeed, when you use these
libraries, you can focus entirely on the graph drawing issues and you will not even notice that your code “is
talking to Lua.” (Except for the name of the entry point, which is fixed to start with luaopen_ and it is
impossible to change this without disrupting a lot inside Lua’s module system).
There are libraries available for simplifying the communication between the graph drawing system and
graph drawing algorithms written in
• C, see Section 36.2,
• C++, see Section 36.3,
• Open Graph Drawing Framework, see Section 36.4.
36.2
36.2.1
Writing Graph Drawing Algorithms in C
The Hello World of Graph Drawing in C
As our first example, as always, the “hello world” of graph drawing simply places nodes on a circle. For this,
we implement a function fast_hello_world in a file SimpleDemoC.c. It starts as follows:
#include
#include
static void fast_hello_world (pgfgd_SyntacticDigraph* graph) {
...
}
As we can see, we first include a special header file of a rather small library that does all the hard work
of translating between Lua and C for us (InterfaceFromC). These header files reside in the c subdirectory
of the pgf package. Note that we do not have to include the headers of the Lua library; indeed, you do not
need access to the source of Lua to use the interface headers. As a side effect, we will, however, have to write
struct lua_State instead of the more common lua_State once in our code, namely in the declaration of
the entry point; but that is the only downside.
The library InterfaceFromC declares the type pgfgd_SyntacticDigraph. In a moment, we will see that
we can setup a key fast simple demo layout such that when this key is used on the display layer, the
function fast_hello_world gets called. When it is called, the graph parameter will be a full representation
of the to-be-laid-out graph. We can access the fields of the graph and even directly modify some of its fields
(in particular, we can modify the pos fields of the vertices). Here is the complete code of the algorithm:
static void fast_hello_world (pgfgd_SyntacticDigraph* graph) {
double angle = 6.28318530718 / graph->vertices.length;
double radius = pgfgd_tonumber(graph->options, "fast simple demo radius");
int i;
for (i = 0; i < graph->vertices.length; i++) {
pgfgd_Vertex* v = graph->vertices.array[i];
v->pos.x = cos(angle*i) * radius;
v->pos.y = sin(angle*i) * radius;
}
}
That is all that is needed; the C library will take care of both creating the graph object as all well as of
deleting it and of copying back the computed values of the pos fields of the vertices.
Our next task is to setup the key fast simple demo layout. We can (and must) also do this from C,
using the following code:
487
int luaopen_pgf_gd_examples_c_SimpleDemoC (struct lua_State *state) {
pgfgd_Declaration* d = pgfgd_new_key ("fast simple demo layout");
pgfgd_key_summary
(d, "The C version of the hello world of graph drawing");
pgfgd_key_algorithm
(d, fast_hello_world);
pgfgd_key_add_precondition (d, "connected");
pgfgd_key_add_precondition (d, "tree");
pgfgd_declare
(state, d)
pgfgd_free_key
(d);
The function luaopen_pgf_gd_examples_c_SimpleDemoC is the function that will be called by Lua
(we will come to that). More important for us, at the moment, is the declaration of the key: We use
pgfgd_new_key to create a declaration record and then fill the different fields using appropriate function
calls. In particular, the call pgfgd_key_algorithm allows us to link the key with a particular C function.
The pgfgd_declare will then pass the whole declaration back to Lua, so the effect of the above is essentially
the same as if you had written in Lua:
declare {
key = "fast simple demo layout",
summary = "The C version of the hello world of graph drawing",
preconditions = {
connected = true,
tree = true,
},
algorithm = {
run = -- something magic we cannot express in Lua
}
}
In our algorithm, in addition to the above key, we also use the fast simple demo radius key, which is
a simple length key. This key, too, can be declared on the C layer:
d = pgfgd_new_key
pgfgd_key_summary
pgfgd_key_type
pgfgd_key_initial
pgfgd_declare
pgfgd_free_key
("fast simple demo radius");
(d, "A radius value for the hello world of graph drawing");
(d, "length");
(d, "1cm");
(state, d);
(d);
return 0;
}
We simply add this code to the startup function above.
Now it is time to compile and link the code. For this, you must, well, compile it, link it against the
library InterfaceFromC, and build a shared library out of it. Also, you must place it somewhere where
LuaTEX will find it. You will find a Makefile that should be able to achieve all of this in the directory
pgf/c/graphdrawing/pgf/gd/examples/c, where you will also find the code of the above example.
Now, all you need to do to use it is to write in Lua (after you have loaded the pgf.gd library, of course),
would normally be the call
require ’pgf.gd.examples.c.SimpleDemoC’
or in Tik Z
\usegdlibrary {examples.c.SimpleDemoC}
This should cause LuaTEX to find the shared library, load it, and then call the function in that library
with the lengthy name (the name is always luaopen_ followed by the path and filename with slashes replaced
by underscores).
Remark: Unfortunately, the above does not work with the TEXLive 2013 versions of LuaTEX due to a
bugs that causes the “replace dots by slashes” to fail. For this reason, we currently need to rename our
sharded library file to
pgf_gd_examples_c_SimpleDemoC.so
and then say
require ’pgf_gd_examples_c_SimpleDemoC’
or in Tik Z
488
\usegdlibrary {pgf_gd_examples_c_SimpleDemoC}
In future versions of LuaTEX, things should be “back to normal” in this regard. Also, the bug only
concerns shared libraries; you can still create a normal Lua file with a nice name and place at a nice location
and the only contents of this file is then the above require command.
Anyway, once we have loaded the shared library we can say:
\tikz \graph [fast simple demo layout, fast simple demo radius=1.25cm]
{ a -> b -> c -> d -> e -> a };
36.2.2
Documenting Algorithms Written in C
In our above example, we included a summary with the keys in the C code. It would be even better if we added
a longer documentation and some examples that show how the key works; but this is a bit impracticable in C
since multi-line strings are hard to write down in C. The trick is to use the documentation_in field of a key:
It allows us to specify the name of a Lua file that should be loaded (using require) to install the missing
documentation fields. As explained in Section 35.2.7, this Lua file may make good use the pgf.gd.doc
package. Note, also, that for keys documented in this way the documentation can easily be included in this
manual through the use of the \includedocumentationof command.
In our example, we would first add the following line twice in the C code (once for each key), assuming
that the documentation resides in the file pgf/gd/doc/examples/SimpleDemoC.lua:
pgfgd_key_documentation_in (d, "pgf.gd.doc.examples.SimpleDemoC");
Note that since the documentation is a normal Lua file, it will be searched in the usual places Lua files
are located (in the texmf trees) and not, like the C shared library, in the special lib subdirectory of the
LuaTEX binary.
Here are typical contents of the documentation file:
-- File pgf/gd/doc/examples/SimpleDemoC.lua
local key
= require ’pgf.gd.doc’.key
local documentation = require ’pgf.gd.doc’.documentation
local summary
= require ’pgf.gd.doc’.summary
local example
= require ’pgf.gd.doc’.example
key
"fast simple demo layout"
documentation
[[
This layout is used...
]]
example
[[
\tikz \graph [fast simple example layout]
{ a -- b -- c -- d -- e; };
]]
key
"fast simple demo radius"
documentation
[[
The radius parameter is used to ...
]]
example
[[
\tikz \graph [fast simple demo layout, fast simple demo radius=1.25cm]
{ a -> b -> c -> d -> e -> a };
]]
36.2.3
The Interface From C
In the above example, we already saw some of the functions from the library InterfaceFromC that translated from Lua to C for us. For a complete list of all functions available, currently please see graphdrawing/c/pgf/gd/interface/c/InterfaceFromC.h directly.
Currently, the library provides C functions to directly access all aspects of the syntactic digraph and also
of the graphs computed by the preprocessing of the layout pipeline. What is missing, however, is access to
the tree of (sub)layouts and to collections. Hopefully, these will be added in the future.
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36.3
Writing Graph Drawing Algorithms in C++
Built on top of the C interface presented in the previous section, there is also a C++ interface available. It
encapsulates as much of the C functions as possible in C++ classes. Thus, this interface is mostly there for
convenience, it does not offer fundamentally new functionality.
36.3.1
The Hello World of Graph Drawing in C++
Let us have a look at how our beloved hello world of graph drawing looks in C++. Although it is still
possible to put graph drawing algorithms inside functions, it is more natural in C++ to turn them into
methods of a class. Thus, we start the code of SimpleDemoCPlusPlus.c++ as follows:
#include
#include
#include
struct FastLayout : scripting::declarations, scripting::runner {
...
}
As can be seen, we do not only include the interface from C++, but also that from C (since, currently,
not all functionality of the C library is encapsulated in C++).
The interesting part is the struct FastLayout, which will contain our algorithm (you could just as well
have used a class instead of a struct). It is derived from two classes: First, from a declarations class
and, secondly, from a runner class. Both of them, just like everything else from the interface, reside in the
namespace scripting. This name was chosen since the main purpose of the interface is to provide “scripting
facilities” to C code through the use of Lua.
We are currently interested in the class runner. This class has a virtual function run that gets called
when, on the Lua side, someone has selected the algorithm represented by the class. Thus, we place our
algorithm in this method:
void run () {
pgfgd_SyntacticDigraph* graph = parameters->syntactic_digraph;
double angle = 6.28318530718 / graph->vertices.length;
double radius = parameters->option("fast simple demo radius c++");
for (int i = 0; i < graph->vertices.length; i++) {
pgfgd_Vertex* v = graph->vertices.array[i];
v->pos.x = cos(angle*i) * radius;
v->pos.y = sin(angle*i) * radius;
}
}
The run method has access to the member variable parameters, which contains all sorts of information
concerning the to-be-drawn graph. In particular, the syntactic_digraph field gives us access to the syntactic
digraph structure that was already available in the interface from plain C. However, we can also see that a
template function like option allows us to access the graph’s option table in a simple way.
As for C code, our next task is to setup a key that, when used on the Tik Z layer, will run our algorithm.
For this, we can use an object derived from a declarations. In our example, the FastLayout is both
derived from a runner (since it contains an algorithm) and also from declarations (since it also contains
the code necessary for declaring this algorithm). If you prefer, you can split this into two classes. A
declarations object must override the declare method. This method gets a script object as input, which
is the “representation” of Lua inside the C++ code:
490
void declare(scripting::script s) {
using namespace scripting;
s.declare(key ("fast simple demo layout c++")
.summary ("The C++ version of the hello world of graph drawing")
.precondition ("connected")
.precondition ("tree")
.algorithm (this));
s.declare(key ("fast simple demo radius c++")
.summary ("A radius value for the hello world of graph drawing")
.type ("length")
.initial ("1cm"));
}
For each key that we wish to declare, we call the script’s declare method once. This method takes a
key object as input, which can be configured through a sequence of calls to different member functions (like
summary or algorithm). Most of these member functions are rather self-explaining; only algorithm is a bit
trickier: It does not take a function as input, but rather an object of type runner and it will call the run
method of this object whenever the algorithm is run.
Lastly, we also need to write the entry point:
extern "C" int luaopen_pgf_gd_examples_c_SimpleDemoCPlusPlus (struct lua_State *state) {
scripting::script s (state);
s.declare (new FastLayout);
return 0;
}
Note that it is the job of the interface classes to free the passed declarations object. For this reason,
you really need to call new and cannot pass the address of a temporary object.
As before, because of the bug in some LuaTEX versions, to actually load the library at runtime, we need
to rename it to
pgf_gd_examples_c_SimpleDemoCPlusPlus.so
and then say
require ’pgf_gd_examples_c_SimpleDemoCPlusPlus’
or in Tik Z
\usegdlibrary {pgf_gd_examples_c_SimpleDemoCPlusPlus}
We can now use it:
\tikz \graph [fast simple demo layout c++, fast simple demo radius c++=1.25cm]
{ a -> b -> c -> d -> e -> a };
36.3.2
The Interface From C++
The header graphdrawing/c/pgf/gd/interface/c/InterfaceFromC++.h contains, as the name suggest,
the interface from C++. A complete documentation is still missing, but let us go over the main ideas:
Runners. Algorithms are represented by objects of type runner. An algorithm will overwrite the run
method, as we saw in the example, and it should modify the parameters of the runner object.
In addition to the run method, there are also two more virtual methods, called bridge and unbrigde.
The first is called before the run method is called and the second afterwards. The idea is that another
framework, such as ogdf, can implement a new class ogdf_runner that overrides these two methods in
order to transform the Lua/C representation of the input graph into an ogdf representation prior to the
run method being called. The run method can then access additional member variables that store the graph
representations in ogdf form (or another form, depending on the framework). The unbridge method allows
the framework to translate back.
Although a runner object must be created for every algorithm, an algorithm can also reside in a function.
The class function_runner is a simple wrapper that turns a function into such an object.
Keys. A key object is a temporary object that is passed to the declare method of a script. It represents
the table that is passed to the Lua function declare. In order to make setting its field easy, for each field
name there is a corresponding function (like summary) that takes the string that should be set to this field
and returns the key object once more, so that we can chain calls.
491
The algorithm method gets a runner object as parameter and will store a pointer to this object inside
Lua. Each time the algorithm is used, this object will be used to “run” the algorithm, that is, the methods
prepare, bridge, run, and unbridge will be called in that order. Since the object is reused each time, only
one object is needed; but this object may not be freed prematurely. Indeed, you will normally create the
object using new once and will then never delete it.
A typical idiom you may find in the code is
s.declare (key (...)
.algorithm(this)
...);
This code is seen inside the declare method of objects that are both declarations and runners. They
register “themselves” via the above code. Note, however, that this requires that the this pointer is not
a temporary object. (The typing rules of C++ make it hard for this situation to happen, but it can be
achieved.)
Reading options. Once options have been declared, your C++ algorithms will wish to read them back.
For this, the parameters field of a runner object provides a number of templated methods:
• The option_is_set method returns true if the passed option has been set and can be cast to
the type of the template. So, option_is_set("node distance") will return true if the
node distance key has been set for the graph as a whole (currently, there is no way to read the
options of a vertex or an edge from C++, use the C methods instead).
• The option function comes in two flavours: First, it takes a single option name and just returns the
option’s value. If, however, the option has not been set or has another type, some sort of null value
is returned. So, option("node distance") will return the configured node distance as a
double. When an option has an initial value, this call will always return a sensible value.
The second flavour of option allows you to pass a reference to an object in which the option’s value
should be stored and the function will return true if the option is set (and, thus, something was written
into the reference). This is the “safest” way to access an option:
double dist;
if (parameters->option ("node distance", dist))
...
Caution must be taken for char* options: The returned string must be explicitly freed; it will be a
copy of the string stored in the Lua table.
• The configure_option method is used to set a member of an object based on the value of a certain
option. For this, you must pass a pointer to a member function that sets the member. Here is an
example:
class MyClass {
public:
void setMyDistance (double distance);
...
};
...
MyClass m;
parameters->configure_option("node distance", &MyClass::setMyDistance, m);
If the option has not been set or does not have the correct type, the member function is not called.
Factories and modules. A Lua key is normally either a Boolean, a double, or a string. However, in C++,
we may also sometimes wish Lua users to configure which C function is used to achieve something. One
could do this using strings or numbers and then use search algorithms or a long switch, but this would
neither be flexible nor elegant.
Instead, it is possible to store factories in Lua keys. A factory is a class derived from factory that
implements the virtual function make. This function will return a new object of a template type. You can
store such a factory in a key.
The make method of a parameters object allows you to invoke the factory stored in a key. (If no factory
is stored in it, null is returned).
492
The configure_module method is akin to configure_option, only the result of applying the factory is
passed to the member function of the class.
Scripts. A “script” is the abstraction of the communication between Lua and C++. From C++’s point
of view, the script object offers different declare methods that allow us to “make objects and function
scriptable” in the sense that they can then be called and configured from Lua. The script must be initialized
with a Lua state and will be bound to that state (basically, the script only stores this single pointer).
When you call declare, you either pass a single key object (which is then declared on the Lua layer) or
you pass a declarations object, whose virtual declare method is then called. The declarations objects
are used to bundle several declarations into a single one.
36.4
Writing Graph Drawing Algorithms Using OGDF
Built on top of the C++ interface, a small interface allows you to easily link algorithms written for the ogdf
(Open Graph Drawing Framework) with graph drawing in Lua.
36.4.1
The Hello World of Graph Drawing in OGDF – From Scratch
We start with some startup code:
#include
#include
using namespace ogdf;
using namespace scripting;
Note that the interface from ogdf resides in the ogdf folder, not in the interface folder.
Like in the plain C++ interface, we must now subclass the runner class and the declarations class.
Also like the plain C++ interface, we can use multiple inheritance. The difference lies in the fact that we
do not directly subclass form runner, but rather from ogdf_runner. This class implements the complicated
“bridging” or “translation” process between the world of InterfaceFromC++ and ogdf:
struct FastLayoutOGDF : declarations, ogdf_runner {
void run () {
double angle = 6.28318530718 / graph.numberOfNodes();
double radius = parameters->option("my radius ogdf");
int i = 0;
for (node v = graph.firstNode(); v; v=v->succ(), i++) {
graph_attributes.x(v) = cos(angle*i) * radius;
graph_attributes.y(v) = sin(angle*i) * radius;
}
}
As can be seen, in a subclass of ogdf_runner, the run method will have access to a member called graph
and to another member called graph_attributes. These will have been setup with the graph from the Lua
layer and, after the algorithm has run, the information stored in the x and y fields of the graph attributes
and also the bend information of the edges will be written back automatically.
Next, we need to declare the algorithm. This is done as in the plain C++ interface:
void declare(script s) {
using namespace scripting;
s.declare(key ("fast simple demo layout ogdf")
.summary ("The OGDF version of the hello world of graph drawing")
.precondition ("connected")
.algorithm (this));
s.declare(key ("my radius ogdf")
.summary ("A radius value for the hello world of graph drawing")
.type ("length")
.initial ("1cm"));
}
};
Finally, we need the entry point, which is also “as usual”:
493
extern "C" int luaopen_pgf_gd_examples_c_SimpleDemoOGDF (struct lua_State *state) {
script (state).declare (new FastLayoutOGDF);
return 0;
}
Yet again, we need to rename the resulting shared library and then say require on it. We can now use
it:
\tikz \graph [fast simple demo layout ogdf, my radius ogdf=1cm]
{ a -> b -> c -> d -> e -> a };
36.4.2
The Hello World of Graph Drawing in OGDF – Adapting Existing Classes
In the previous example we implemented a graph drawing algorithm using ogdf for use with Lua “from
scratch.” In particular, the whole algorithm was contained in the run method of our main class. In practice,
however, graph drawing algorithms are typically placed in classes that “know nothing about scripting.” For
instance, our hello world of graph drawing might actually be implemented like this:
// File HelloWorldLayout.h
#include
class HelloWorldLayout : puplic ogdf::LayoutModule {
public:
virtual void call(ogdf::GraphAttributes &GA)
{
using namespace ogdf;
const Graph &graph = GA.constGraph();
double angle = 6.28318530718 / graph.numberOfNodes();
int i = 0;
for (node v = graph.firstNode(); v; v=v->succ(), i++) {
GA.x(v) = cos(angle*i) * radius;
GA.y(v) = sin(angle*i) * radius;
}
}
void setRadius (double r) { radius = r; }
private:
double radius;
};
Now, what we actually want to do is to “make this class scriptable”. For this, we setup a new class whose
run method will produce a new HelloWorldLayout, configure it, and then run it. Here is this run method:
void run ()
{
HelloWorldLayout layout;
parameters->configure_option("HelloWorldLayout.radius", &HelloWorldLayout::setRadius, layout);
layout.call(graph_attributes);
}
Next, we need to write the declarations code. This is very similar to the “from scratch” version:
void declare(script s) {
using namespace scripting;
s.declare(key ("HelloWorldLayout")
.summary ("The OGDF version of the hello world of graph drawing")
.precondition ("connected")
.algorithm (this));
s.declare(key ("HelloWorldLayout.radius")
.summary ("A radius value for the hello world of graph drawing")
.type ("length")
.alias ("radius"));
}
Two remarks are in order: First, it is customary to name the keys for the display system the same way
as the classes. Second, the different configuration options of the algorithm are named with the class name
494
followed by the option name. This makes it clear who, exactly, is being configured. However, these keys
should then also get an alias field set, which will cause an automatic forwarding of the key to something
more “user friendly” like just radius.
It remains to put the above methods in a “script” file. It is this file that, when compiled, must be linked
at runtime against LuaTEX.
// File HelloWorldLayout_script.c++
#include
#include
using namespace ogdf;
using namespace scripting;
struct HelloWorldLayout_script : declarations, ogdf_runner {
void run ()
{ ... see above ... }
void declare (script s) { ... see above ... }
};
extern "C" int luaopen_my_path_HelloWorldLayout_script (struct lua_State *state) {
script (state).declare (new HelloWorldLayout_script);
return 0;
}
36.4.3
Documenting OGDF Algorithms
As explained in Section 36.2.2, we can add external documentation to algorithms written in C and, using
the documentation_in method of the key class, we can use the exact same method to document ogdf
algorithms.
I strongly recommend making use of this feature since, currently, the documentation of many ogdf
classes is sketchy at best and using Tik Z examples seems to be a good way of explaining the effect of the
different parameters algorithms offer.
36.4.4
The Interface From OGDF
The support for ogdf offered inside InterfaceFromOGDF.h is just the class ogdf_runner we saw already in
the example. In addition, there is also a wrapper class ogdf_function_runner that allows you to wrap an
algorithm implemented in a function that uses ogdf, but I expect this to be the case only rarely.
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37
The Display Layer
by Till Tantau
You do not need to read this section in order to write new graph drawing algorithms. It is of
interest only to those wishing to write programs that wish to “use” the graph drawing system in a
similar way that Ti kZ does for laying out graphs that are generated and then passed down from
the program to the graph drawing system.
37.1
Introduction: The Interplay of the Different Layers
The job of the graph drawing system is to run graph drawing algorithms on graphs. Since graph drawing is
useful in many different contexts, not only in the context of Tik Z for which the present system was originally
developed, the graph drawing system was designed in such a way that it can be used independently of Tik Z.
To achieve this, the display layer provides an interface via which an arbitrary program (Tik Z, a graph editor,
a command line interface, etc.) “talk” to the graph drawing system.
To better understand how this works, let us consider the following setup:
• A program would like to communicate with the graph drawing system. It is written in Java and its
job is to analyse social networks. This software would like to use graph drawing to produce drawings
of some “social graphs” arising from its analyses. This software will be called “the display system” in
the following.
• There are two algorithms that the display system would like to apply to the graphs its produces. Let
us call these algorithms “A” and “B”. However, the display system would also, ideally, wish to make it
possible that its user chooses other algorithms “C” that are not necessarily part of its binary.
• The display system has internally generated a “social graph” that it would now like to draw.
For this setup, the communication between the different layers of the graph drawing system is as follows:
1. The display system, being written in Java, must embed Lua to use the graph drawing system.
2. The display system must initialize the graph drawing system. For this, it must use require on the file
InterfaceToDisplay, which, as the name suggests, contains the interface between the display system
and the graph drawing system.
It must also create a so-called “binding” between the graph drawing system and the display layer. See
Section 38 for more information on bindings.
3. The display system now needs to load the declarations of the algorithms A and B. For this, it just needs
to apply require to the files in which the algorithms reside. This will cause the declare function to
be called. This function is declared by InterfaceToAlgorithms and allows files to declare that certain
algorithms and options are now available.
Once this is done, the graph drawing system is fully initialized and can be used.
4. Later on, the display system wishes to lay out a social graph. Note that this is known as “drawing the
graph” in the graph drawing community, even though this only means the coordinates are computed
for the nodes of the graph. The actual “rendering” of the graph on the display is the job of the display
system (hence the name “display layer”).
5. To start the layout process, the display system calls the function beginGraphDrawingScope of the
class InterfaceToDisplay.
6. Next, for each vertex the function createVertex of the interface class must be called and similarly for
each edge. These calls will cause an internal model of the graph to be created on the algorithm layer.
Options that are attached to nodes and edges are also communicated to the graph drawing system
through function calls like pushOption.
7. When the graph is fully specified, the method runGraphDrawingAlgorithm must be called, which is
once more a method of the interface class. This function will internally discern which algorithms have
been chosen (via options) and invoke the code of the appropriate algorithms.
496
8. Next, the function renderGraph must be called. Its job is to “communicate back” which coordinates
have been computed. It will use the binding for this communication, see Section 38.
9. Finally, by calling endGraphDrawingScope, the resources needed for the layout process for the social
graph are freed once more.
A few points may be noteworthy:
• The whole communication between the display system and the graph drawing system goes through
the interface class via function calls. This makes it easy to communicate with display system whose
internal model of graphs is quite different from the one used in Lua (as is certainly the case for TEX,
but also the “social graph” mentioned above need not even exist as a separate entity inside the display
system).
The display system should only rely on the interface class. All communication has to go through this
class, the display system may not access the internals of the internally constructed graphs directly.
• New algorithms can be loaded at runtime, as long as the require method is supported.
• The display system can also use the interface class to query which algorithms and which options are
available in principle (and display this information to the user). The display system can even get access
the documentation of the options at runtime since the documentation is stored in fields of the declared
options.
In the following, we first present a simple display system other than Tik Z. The remainder of the section
then encompasses a documentation of the different functions of the class InterfaceToDisplay.
37.2
An Example Display System
In the following, we present the code of a very simple display system written in Lua (another such display
system is Tik Z itself, but the minimal system will allow us to focus on what is really needed). You will also
find it in pgf.gd.examples.ASCIIDisplayer.
The job of this display system is to parse a string that encodes a graph and to call the appropriate
functions of InterfaceToDisplay to lay out the graph. The actual calls for rendering the graph are part of
the binding, which is documented in Section 38.4.
The syntax of the to-be-laid-out graph is a reduced version of Tik Z’s graph syntax: The string must
start with graph[halgorithm’s namei]{ and end with }. Between the braces, all lines must either be of the
form hnode namei; or hname 1 i->hname 2 i; with optional spaces around the node names.
Let us now have a look at what we must do to use the graph drawing system. First, we load some
libraries and initialize the binding (see Section 38.4 for details on the binding; we can ignore it for now).
local InterfaceToDisplay = require "pgf.gd.interface.InterfaceToDisplay"
InterfaceToDisplay.bind(require "pgf.gd.examples.BindingToASCII")
-- Load two libraries that define graph drawing algorithms. We can do this only *after* the binding
-- has been created since they call the declare function internally.
require "pgf.gd.layered.library"
require "pgf.gd.force.library"
Now comes some preparation code that starts a graph drawing scope and sets up the algorithm to the
string provided between the square brackets:
local algorithm = io.read():match("%s*graph%s*%[(.-)%]")
InterfaceToDisplay.pushPhase(algorithm, "main", 1)
InterfaceToDisplay.pushOption("level distance", 6, 2)
InterfaceToDisplay.pushOption("sibling distance", 8, 3)
InterfaceToDisplay.beginGraphDrawingScope(3)
InterfaceToDisplay.pushLayout(4)
The numbers 1 to 4 are the positions on the options stack at which the options should be placed. See
the description of pushOption for more details.
We are now ready to create the vertices and edges via a very simple parser:
497
for line in io.lines() do
if line:match("}") then
break
elseif line:find("-") then
local n1, dir, n2 = string.match(line, "^%s*(.-)%s*(-.)%s*(.-)%s*;")
InterfaceToDisplay.createEdge(n1, n2, dir, 4)
else
local n1 = string.match(line, "^%s*(.-)%s*;")
InterfaceToDisplay.createVertex(n1, "rectangle", nil, 4)
end
end
The graph is now completely constructed inside the graph drawing system. We can now invoke the
algorithms:
InterfaceToDisplay.runGraphDrawingAlgorithm()
InterfaceToDisplay.renderGraph()
InterfaceToDisplay.endGraphDrawingScope()
We can now run the resulting file using the Lua interpreter. If we provide the input shown on the left,
we get the output shown on the right:
Input given to ASCIIDisplayer:
Output produced by ASCIIDisplayer:
graph [layered layout] {
Alice;
Bob;
Charly;
Dave;
Eve;
Fritz;
George;
Alice -> Bob;
Alice -> Charly;
Charly -> Dave;
Bob -> Dave;
Dave -> Eve;
Eve -> Fritz;
Fritz -> Alice;
George -> Eve;
George -> Fritz;
Alice -> George;
}
37.3
Alice
.......
.. . . .
... .
.
.
...
..
.
..
..
.
.
.
Charly
Bob
.
.
..
.
.
.
.
.
.
.
.
.
.
.
.. .
.
.
..
.
.
Dave
George
.
..
. ...
.
.
.
.. .
.
.
...
.. .
. ...
..
.
..
Eve
.
..
..
.
..
.
.
.
.
.
.
.. . ..
...
Fritz
The Interface to Display Systems
Lua table InterfaceToDisplay (declared in pgf.gd.interface.InterfaceToDisplay)
This class provides the interface between a display layer (like Tik Z or a graph editor) and graph drawing
system. Another class, InterfaceToAlgorithms, binds the algorithm layer (which are written in Lua)
to the graph drawing system.
The functions declared here are independent of the actual display layer. Rather, the differences between
the layers are encapsulated by subclasses of the Binding class, see that class for details. Thus, when a
new display layer is written, the present class is used, but not modified. Instead, only a new binding is
created and all display layer specific interaction is put there.
The job of this class is to provide convenient methods that can be called by the display layer. For
instance, it provides methods for starting a graph drawing scope, managing the stack of such scope,
adding a node to a graph and so on.
Alphabetical method summary:
function InterfaceToDisplay.addToVertexOptions (name, height)
498
function InterfaceToDisplay.beginGraphDrawingScope (height)
function InterfaceToDisplay.bind (class)
function InterfaceToDisplay.createEdge (tail, head, direction, height, binding_infos)
function InterfaceToDisplay.createEvent (kind, param)
function InterfaceToDisplay.createVertex (name, shape, path, height, binding_infos, anchors)
function InterfaceToDisplay.endGraphDrawingScope ()
function InterfaceToDisplay.getDeclaredKeys ()
function InterfaceToDisplay.pushLayout (height)
function InterfaceToDisplay.pushOption (key, value, height)
function InterfaceToDisplay.pushSubgraphVertex (name, height, info)
function InterfaceToDisplay.renderGraph ()
function InterfaceToDisplay.resumeGraphDrawingCoroutine ()
function InterfaceToDisplay.runGraphDrawingAlgorithm ()
function InterfaceToDisplay.bind(class)
Initiliaze the binding. This function is called once by the display layer at the very beginning. For
instance, Tik Z does the following call:
InterfaceToDisplay.bind(require "pgf.gd.bindings.BindingToPGF")
Inside this call, many standard declarations will be executed, that is, the declared binding will be used
immediately.
Subsequently, the binding field of the InterfaceCore can be used.
Parameters: 1. class A subclass of Binding.
function InterfaceToDisplay.beginGraphDrawingScope(height)
Start a graph drawing scope. Note that this is not the same as starting a subgraph / sublayout, which
are local to a graph drawing scope: When a new graph drawing scope is started, it is pushed on top
of a stack of graph drawing scopes and all other “open” scopes are no longer directly accessible. All
method calls to an Interface... object will refer to this newly created scope until either a new scope
is opened or until the current scope is closed once more.
Each graph drawing scope comes with a syntactic digraph that is build using methods like addVertex
or addEdge.
Parameters: 1. height The to-be-used height of the options stack. All options above this height will
be popped prior to attacking the options to the syntactic digraph.
function InterfaceToDisplay.runGraphDrawingAlgorithm()
Arranges the current graph using the specified algorithm and options.
This function should be called after the graph drawing scope has been opened and the syntactic digraph has been completely specified. It will now start running the algorithm specified through the
algorithm_phase options.
Internally, this function creates a coroutine that will run the current graph drawing algorithm. Coroutines are needed since a graph drawing algorithm may choose to create a new node. In this case, the
algorithm needs to be suspended and control must be returned back to the display layer, so that the
node can be typeset in order to determine the precise size information. Once this is done, control must
be passed back to the exact point inside the algorithm where the node was created. Clearly, all of these
actions are exactly what coroutines are for.
Returns: 1. Time it took to run the algorithm
function InterfaceToDisplay.resumeGraphDrawingCoroutine()
Resume the graph drawing coroutine.
This function is the work horse of the coroutine management. It gets called whenever control passes
back from the display layer to the algorithm level. We resume the graph drawing coroutine so that the
algorithm can start/proceed. The tricky part is when the algorithm yields, but is not done. In this case,
the code needed for creating a new node is passed back to the display layer through the binding, which
must then execute the code and then resuming the coroutine.
499
function InterfaceToDisplay.endGraphDrawingScope()
Ends the current graph drawing scope.
function InterfaceToDisplay.createVertex(name, shape, path, height, binding_infos,
anchors)
Creates a new vertex in the syntactic graph of the current graph drawing scope. The display layer
should call this function for each node of the graph. The name must be a unique string identifying
the node. The newly created vertex will be added to the syntactic digraph. The binding function
everyVertexCreation will then be called, allowing the binding to store information regarding the
newly created vertex.
For each vertex an event will be created in the event sequence. This event will have the kind "node"
and its parameter will be the vertex.
Parameters: 1. name Name of the vertex.
2. shape The shape of the vertex such as "circle" or "rectangle". This shape may help a graph
drawing algorithm figuring out how the node should be placed.
3. path A Path object representing the vertex’s path.
4. height The to-be-used height of the options stack. All options above this height will be popped
prior to attacking the options to the syntactic digraph.
5. binding_infos These options are passed to and are specific to the current Binding.
6. anchors A table of anchors (mapping anchor positions to Coordinates).
function InterfaceToDisplay.pushSubgraphVertex(name, height, info)
Creates a new vertex in the syntactic graph of the current graph drawing scope that is a subgraph
vertex. Such a vertex “surrounds” the vertices of a subgraph. The special property of a subgraph node
opposed to a normal node is that it is created only after the subgraph has been laid out. However, the
difference to a collection like hyper is that the node is availble immediately as a normal node in the
sense that you can connect edges to it.
What happens internally is that subgraph nodes get “registered” immediately both on the display level
and on the algorithm level, but the actual node is only created inside the layout pipeline using a callback
of the binding. The present function is used to perform this registering. The node creation happens
when the innermost layout in which the subgraph node is declared has finished. For each subgraph
node, a collection is created that contains all vertices (and edges) being part of the subgraph. For this
reason, this method is a push... method, since it pushes something on the options stack.
The init parameter will be used during the creation of the node, see Binding:createVertex for details
on the fields. Note that init.text is often not displayed for such “vast” nodes as those created for whole
subgraphs, but a shape may use it nevertheless (for instance, one might display this text at the top of
the node or, in case of a uml package, in a special box above the actual node).
The init.generated_options will be augmented by additional key–value pairs when the vertex is
created:
• The key subgraph point cloud will have as its value a string that is be a list of points (without
separating commas) like "(10pt,20pt)(0pt,0pt)(30pt,40pt)", always in this syntax. The list
will contain all points inside the subgraph. In particular, a bounding box around these points will
encompass all nodes and bend points of the subgraph. The bounding box of this point cloud is
guaranteed to be centered on the origin.
• The key subgraph bounding box width will have as its value the width of a bounding box (in
TEX points, as a string with the suffix "pt").
• The key subgraph bounding box height stores the height of a bounding box.
Parameters: 1. name The name of the node.
2. height Height of the options stack. Note that
this method pushes something (namely a collection) on the options stack. 3. info A table passed to
Binding:createVertex, see that function.
function InterfaceToDisplay.addToVertexOptions(name, height)
Add options for an already existing vertex.
500
This function allows you to add options to an already existing vertex. The options that will be added
are all options on the current options stack; they will overwrite existing options of the same name.
For collections, the vertex stays in all collections it used to, it is only added to all collections that are
currently on the options stack.
Parameters: 1. name Name of the vertex. 2. height The option stack height.
function InterfaceToDisplay.createEdge(tail, head, direction, height, binding_infos)
Creates a new edge in the syntactic graph of the current graph drawing scope. The display layer should
call this function for each edge that is created. Both the from vertex and the to vertex must exist (have
been created through createVertex) prior to your being able to call this function.
After the edge has been created, the binding layer’s function everyEdgeCreation will be called, allowing
the binding layer to store information about the edge.
For each edge an event is created, whose kind is "edge" and whose parameter is a two-element array
whose first entry is the edge’s arc in the syntactic digraph and whose second entry is the position of the
edge in the arc’s array of syntactic edges.
Parameters: 1. tail Name of the node the edge begins at. 2. head Name of the node the edge ends
at. 3. direction Direction of the edge (e.g. -- for an undirected edge or -> for a directed edge from
the first to the second node). 4. height The option stack height, see for instance createVertex.
5. binding_infos These options will be stored in the storage of the vertex at the field index by the
binding.
function InterfaceToDisplay.pushOption(key, value, height)
Push an option to the stack of options.
As a graph is parsed, a stack of “current options” is created. To add something to this table, the display
layers may call the method pushOption. To pop something from this stack, just set the height value
during the next push to the position to which you actually wish to push something; everything above
and including this position will be popped from the stack.
When an option is pushed, several additional options may also be pushed, namely whenever the option
has a use field set. These additional options may, in turn, also push new options. Because of this, this
function returns a new stack height, representing the resulting stack height.
In addition to this stack height, this function returns a Boolean value indicating whether a “main
algorithm phase was set.” This happens whenever a key is executed (directly or indirectly through the
use field) that selects an algorithm for the “main” algorithm phase. This information may help the
caller to setup the graph drawing scopes correctly.
Parameters: 1. key A parameter (must be a string). 2. value A value (can be anything). If it is a
string, it will be converted to whatever the key expects. 3. height A stack height at which to insert
the key. Everything above this height will be removed.
Returns: 1. A new stack height
Returns: 1. A Boolean that is true iff the main algorithm phase was set by the option or one option
used by it.
Returns: 1. The newly created entry on the stack. If more entries are created through the use of the
use field, the original entry is returned nevertheless.
function InterfaceToDisplay.pushLayout(height)
Push a layout on the stack of options. As long as this layout is on the stack, all vertices and edges will
be part of this layout. For details on layouts, please see Sublayouts.
Parameters: 1. height A stack height at which to insert the key. Everything above this height will be
removed.
function InterfaceToDisplay.createEvent(kind, param)
Creates an event and adds it to the event string of the current scope.
Parameters: 1. kind Name/kind of the event. 2. parameters Parameters of the event.
Returns: 1. The newly pushed event
function InterfaceToDisplay.getDeclaredKeys()
501
This method allows you to query the table of all declared keys. It contains them both as an array and
also as a table index by the keys’s names. In particular, you can then iterate over it using ipairs and
you can check whether a key is defined by accessing the table at the key’s name. Each entry of the table
is the original table passed to InterfaceToAlgorithms.declare.
Returns: 1. A lookup table of all declared keys.
function InterfaceToDisplay.renderGraph()
Renders the graph.
This function is called after the graph has been laid out by the graph drawing algorithms. It will trigger
a sequence of calls to the binding layer that will, via callbacks, start rendering the whole graph.
In detail, this function calls:
local binding = InterfaceCore.binding
binding:renderStart()
render_vertices()
render_edges()
render_collections()
binding:renderStop()
Here, the render_... functions are local, internal functions that are, nevertheless, documented here.
Parameters:
given name.
1. name Returns the algorithm class that has been declared using declare under the
function render_vertices(vertices)
Render the vertices after the graph drawing algorithm has finished. This function is local and internal
and included only for documenting the call graph.
When the graph drawing algorithm is done, the interface will start rendering the vertices by calling
appropriate callbacks of the binding layer.
Consider the following code:
\graph [... layout] {
a -- b -- c -- d;
};
In this case, after the graph drawing algorithm has run, the present function will call:
local binding = InterfaceCore.binding
binding:renderVerticesStart()
binding:renderVertex(vertex_a)
binding:renderVertex(vertex_b)
binding:renderVertex(vertex_c)
binding:renderVertex(vertex_d)
binding:renderVerticesStop()
Parameters: 1. vertices An array of all vertices in the syntactic digraph.
function render_collections(collections)
Render the collections whose layer is not 0. This local, internal function is called to render the different
collection kinds.
Collection kinds rendered in the order provided by the layer field passed to declare during the declaration of the colleciton kind, see also declare_collection. If several collection kinds have the same
layer, they are rendered in lexicographical ordering (to ensure that they are always rendered in the same
order).
Consider the following code:
declare { key = "hyper", layer = 1 }
you can say on the Tik Z layer
502
\graph {
a, b, c, d;
{ [hyper] a, b, c }
{ [hyper] b, c, d }
};
In this case, after the graph drawing algorithm has run, the present function will call:
local binding = InterfaceCore.binding
binding:renderCollectionStartKind("hyper", 1)
binding:renderCollection(collection_containing_abc)
binding:renderCollection(collection_containing_bcd)
binding:renderCollectionStopKind("hyper", 1)
Parameters: 1. collections The collections table of the current scope.
function render_edges(arcs)
Render the syntactic edges of a graph after the graph drawing algorithm has finished. This function is
local and internal and included only for documenting the call graph.
When the graph drawing algorithm is done, the interface will first rendering the vertices using render_vertices, followed by calling this function, which in turn calls appropriate callbacks to the binding
layer.
Consider the following code:
\graph [... layout] {
a -- b -- c -- d;
};
In this case, after the graph drawing algorithm has run, the present function will call:
local binding = InterfaceCore.binding
binding:renderEdgesStart()
binding:renderEdge(edge_from_a_to_b)
binding:renderEdge(edge_from_b_to_c)
binding:renderEdge(edge_from_c_to_d)
binding:renderEdgesStop()
Parameters: 1. arcs The array of arcs of the syntactic digraph.
function get_current_options_table(height, table)
Get the current options table.
An option table can be accessed like a normal table; however, there is a global fallback for this table.
If an index is not defined, the value of this index in the global fallback table is used. (This reduces the
overall amount of option keys that need to be stored with object.)
(This function is local and internal and included only for documentation purposes.)
Parameters: 1. height The stack height for which the option table is required. 2. table If non nil,
the options will be added to this table.
Returns: 1. The option table as described above.
503
38
The Binding Layer
38.1
Overview
This section explains how the binding of the graph drawing system to a particular display layer works. Let
me stress that all of this is important only for readers who
• either wish to write new display system (see Section 37)
• or wish to know more about how the graph drawing system works on the pure pgf layer (this is were
the binding occurs).
Bindings are used to encapsulate the details of the communication between the graph drawing system
and a display system (see Section 37 for an introduction to display systems).
Consider a display system that communicates with the graph drawing system. At some point, the display
system would like to run an algorithm to lay out a graph. To achieve this, it will call different functions from
the class InterfaceToDisplay and the effect of this is that a representation of the to-be-drawn graph is
constructed internally and that the appropriate algorithms are run. All of this is in some sense independent
of the actual display system, the class InterfaceToDisplay offers the same standard interface to all display
systems.
At some point, however, the graph drawing system may need to “talk back” to the display system. For
instance, once the graph has been laid out, to trigger the actual rendering of the graph, the graph drawing
system must “tell” the display layer where the vertices lie. For some display systems this is easy: if the display
system itself is written in Lua, it could just access the syntactic digraph directly. However, for systems like
Tik Z or systems written in another language, the graph drawing system needs a set of functions that it can
call that will tell the display system what is going on. This is were bindings come in.
The class Binding is an interface that defines numerous methods that will be called by the graph drawing
system in different situations (see the documentation below for details). For instance, there is a function
renderVertex that is called by the graph drawing system whenever a vertex should be rendered by the
display system. The class is really just an interface in the sense of object-oriented programming. For
each display system you need to create a subclass of Binding like BindingToPGF or BindingToASCII that
implement the methods declared by Binding. The number of methods that need to be implemented depends
on the display system.
In the following, you will find the documentation of the Binding class in Section 38.2. Following this, we
first have a quick look at how the BindingToPGF works and then go over a simple example of a binding to
a more or less imaginary display system. This example should help readers interested in implementing their
own bindings.
38.2
The Binding Class and the Interface Core
Lua table Binding (declared in pgf.gd.bindings.Binding)
This class provides a (non-functional) default implementation of a binding between a display layer and
the algorithm layer. Subclasses must implement most of the member functions declared in this class.
A instance of a subclass of this class encapsulates the complete implementation of all specific code
needed for the communication between the display layer and the graph drawing engine.
Note that you never call the methods of a Binding object directly, neither from the display layer
nor from the algorithm layer. Instead, you use the more powerful and more easy to use functions
from InterfaceToDisplay and InterfaceToAlgorithms. They call the appropriate Binding methods
internally.
Because of the above, in order to use the graph drawing system inside a new display layer, you need to
subclass Binding and implement all the functions. Then you need to write the display layer in such a
way that it calls the appropriate functions from InterfaceToDisplay.
Field storage
A Storage storing the information passed from the display layer. The interpretation of this left to
the actual binding.
Alphabetical method summary:
function Binding:createVertex (init)
504
function Binding:declareCallback (t)
function Binding:everyEdgeCreation (e)
function Binding:everyVertexCreation (v)
function Binding:renderCollectionStartKind (kind, layer)
function Binding:renderCollectionStopKind (kind, layer)
function Binding:renderCollection (collection)
function Binding:renderEdgesStart ()
function Binding:renderEdgesStop ()
function Binding:renderEdge (edge)
function Binding:renderStart ()
function Binding:renderStop ()
function Binding:renderVertex (vertex)
function Binding:renderVerticesStart ()
function Binding:renderVerticesStop ()
function Binding:declareCallback(t)
Declare a new key. This callback is called by declare. It is the job of the display layer to make the
parameter t.key available to the parsing process. Furthermore, if t.initial is not nil, the display
layer must convert it into a value that is stored as the initial value and call InterfaceToDisplay.setOptionInitial.
Parameters: 1. t See InterfaceToAlgorithms.declare for details.
function Binding:renderStart()
This function and, later on, renderStop are called whenever the rendering of a laid-out graph starts or
stops. See InterfaceToDisplay.render for details.
function Binding:renderStop()
See renderStart.
function Binding:renderCollectionStartKind(kind, layer)
This function and the correspoding ...Stop... functions are called whenever a collection kind should
be rendered. See InterfaceToDisplay.render_collections for details.
Parameters: 1. kind The kind (a string). 2. layer The kind’s layer (a number).
function Binding:renderCollectionStopKind(kind, layer)
The counterpart to renderCollectionStartKind.
Parameters: 1. kind The kind. 2. layer The kind’s layer.
function Binding:renderCollection(collection)
Renders a single collection, see renderCollectionStartKind for details.
Parameters: 1. collection The collection object.
function Binding:renderVerticesStart()
This function and the correspoding ...Stop... functions are called whenever a vertex should be
rendered. See InterfaceToDisplay.render_vertices for details.
function Binding:renderVerticesStop()
The counterpart to renderVerticesStop.
function Binding:renderVertex(vertex)
Renders a single vertex, see renderVertexStartKind for details.
Parameters: 1. vertex The Vertex object.
function Binding:everyVertexCreation(v)
505
This method is called by the interface to the display layer after the display layer has called createVertex
to create a new vertex. After having done its internal bookkeeping, the interface calls this function to
allow the binding to perform further bookkeeping on the node. Typically, this will be done using the
information stored in Binding.infos.
Parameters: 1. v The vertex.
function Binding:renderEdgesStart()
This function and the correspoding ...Stop... functions are called whenever an edge should be
rendered. See InterfaceToDisplay.render_edges for details.
function Binding:renderEdgesStop()
The counterpart to renderEdgesStop.
function Binding:renderEdge(edge)
Renders a single vertex, see renderEdgeStartKind for details.
Parameters: 1. edge The Edge object.
function Binding:everyEdgeCreation(e)
Like everyVertexCreation, only for edges.
Parameters: 1. e The edge.
function Binding:createVertex(init)
Generate a new vertex. This method will be called when the algorithm layer wishes to trigger the
creation of a new vertex. This call will be made while an algorithm is running. It is now the job of the
binding to cause the display layer to create the node. This is done by calling the yield method of the
scope’s coroutine.
Parameters: 1. init A table of initial values for the node. The following fields will be used:
• name If present, this name will be given to the node. If not present, an iternal name is generated.
Note that, unless the node is a subgraph node, this name may not be the name of an already
present node of the graph; in this case an error results.
• shape If present, a shape of the node.
• generated_options A table that is passed back to the display layer as a list of key-value pairs.
• text The text of the node, to be passed back to the higher layer. This is what should be displayed
as the node’s text.
Lua table InterfaceCore (declared in pgf.gd.interface.InterfaceCore)
This class provides the core functionality of the interface between all the different layers (display layer,
binding layer, and algorithm layer). The two classes InterfaceToAlgorithms and InterfaceToDisplay
use, in particular, the data structures provided by this class.
Field binding
This field stores the “binding.” The graph drawing system is “bound” to the display layer through
such a binding (a subclass of Binding). Such a binding can be thought of as a “driver” in operating
systems terminology: It is a small set of functions needed to adapt the functionality to one specific
display system. Note that the whole graph drawing scope is bound to exactly one display layer; to
use several bindings you need to setup a completely new Lua instance.
Field scopes
This is a stack of graph drawing scopes. All interface methods refer to the top of this stack.
Field collection_kinds
This table stores which collection kinds have been defined together with their properties.
Field algorithm_classes
A table that maps algorithm keys (like tree layout to class objects).
506
Field keys
A lookup table of all declared keys. Each entry of this table consists of the original entry passed
to the declare method. Each of these tables is both index at a number (so you can iterate over it
using ipairs) and also via the key’s name.
Alphabetical method summary:
function InterfaceCore.convert (s,t)
function InterfaceCore.topScope ()
function InterfaceCore.topScope()
Returns the top scope
Returns: 1. The current top scope, which is the scope in which everything should happen right now.
function InterfaceCore.convert(s,t)
Converts parameters types. This method is used by both the algorithm layer as well as the display layer
to convert strings into the different types of parameters. When a parameter is pushed onto the option
stack, you can either provide a value of the parameter’s type; but you can also provide a string. This
string can then be converted by this function to a value of the correct type.
Parameters: 1. s A parameter value or a string. 2. t The type of the parameter
Returns: 1. If s is not a string, it is just returned. If it is a string, it is converted to the type t.
38.3
The Binding To PGF
Lua table BindingToPGF (declared in pgf.gd.bindings.BindingToPGF)
This class, which is a subclass of Binding, binds the graph drawing system to the pgf display system
by overriding (that is, implementing) the methods of the Binding class. As a typical example, consider
the implementation of the function renderVertex:
function BindingToPGF:renderVertex(v)
local info = assert(self.infos[v], "thou shalt not modify the syntactic digraph")
tex.print(
string.format(
"\\pgfgdcallbackrendernode{%s}{%fpt}{%fpt}{%fpt}{%fpt}{%fpt}{%fpt}{%s}",
’not yet positionedPGFINTERNAL’ .. v.name,
info.x_min,
info.x_max,
info.y_min,
info.y_max,
v.pos.x,
v.pos.y,
info.box_count))
end
As can be seen, the main job of this function is to call a function on the TEX layer that is called
\pgfgdcallbackrendernode, which gets several parameters like the name of the to-be-rendered node
or the (new) position for the node. For almost all methods of the Binding class there is a corresponding
“callback” macro on the TEX layer, all of which are implemented in the pgf library graphdrawing. For
details on these callbacks, please consult the code of that file and of the class BindingToPGF (they are
not documented here since they are local to the binding and should not be called by anyone other than
the binding class).
38.4
An Example Binding Class
In the present section a complete binding is presented to an imaginary “ascii art display system” is presented.
The idea is that this display system will depict graphs using just normal letters and spaces so that, when
the text is typeset in a monospace font, a visualization of the graph results. For instance:
507
Graph rendered by BindingToPGF:
Graph rendered by BindingToASCII:
Alice
Charly
Alice
.......
.. . . .
... .
.
.
...
..
.
..
..
.
.
.
Charly
Bob
.
.
..
.
.
.
.
.
.
.
.
.
.
.
.. .
.
.
..
.
.
Dave
George
.
..
. ...
.
.
.
.. .
.
.
...
.. .
. ...
..
.
..
Eve
.
..
..
.
..
.
.
.
.
.
.
.. . ..
...
Fritz
Bob
Dave
George
Eve
Fritz
The binding will reside in a file BindingToASCII.lua, whose contents is detailed below, and which is
used by calling the bind function of InterfaceToDisplay, see its documentation for details.
The binding’s code starts with some initializations:
-- File BindingToASCII.lua
-- Imports
local lib = require "pgf.gd.lib"
-- Subclass the Binding class:
local BindingToASCII = lib.class { base_class = require "pgf.gd.bindings.Binding" }
The interesting code is the code for “rendering” a graph. The graph drawing system will invoke the
binding’s methods renderStart and renderStop to signal that the graph drawing algorithms have finished
and that the vertices and edges can now be drawn.
In our ascii renderer, we use a two-dimensional field holding characters that severs as the “drawing
canvas”. At the beginning of the rendering, we initialize it with blanks:
local canvas
function BindingToASCII:renderStart()
canvas = {}
-- Clear the canvas
for x=-30,30 do
canvas [x] = {}
for y=-30,30 do
canvas[x][y] = ’ ’
end
end
end
In order to “render” a vertex, the graph drawing system will call the renderVertex method. The binding
of Tik Z does a lot of complicated things in this method to retrieve the underlying node’s box from internal
table and to somehow reinstall the box in TEX’s output stream; for our ascii binding things are much simpler:
We simply put the vertex’s name at the canvas position corresponding to the vertex’s pos coordinate. Note
that this simple version of an ascii renderer does not try to scale things; thus, array out of bounds might
occur here.
508
function BindingToASCII:renderVertex(v)
canvas [math.floor(v.pos.x)][math.floor(v.pos.y)] = v.name
end
The rendering of edges is a more complicated process. Given two vertices, we put dots at the canvas
positions between them; provided there are no vertices (so edges are behind the nodes). Here is the essential
part of the code (for the complete code, have a look at pgf/gd/examples/BindingToASCII.lua):
function BindingToASCII:renderEdge(e)
local function connect (p,q)
-- Connect the points p and q
local x1, y1, x2, y2 = math.floor(p.x+0.5), math.floor(p.y+0.5), math.floor(q.x+0.5), math.floor(q.y+0.5)
...
local delta_x = x2-x1
local delta_y = y2-y1
...
local slope = delta_y/delta_x
for i=x1,x2 do
local x,y = i, math.floor(y1 + (i-x1)*slope + 0.5)
if canvas[x][y] == " " then
canvas[x][y] = ’.’
end
end
...
end
-- Iterate over all points on the path from tail to head:
local p = e.tail.pos
for i=1,#e.path do
connect(p, e.tail.pos + e.path[i])
p = e.tail.pos + e.path[i]
end
connect(p, e.head.pos)
end
The methods renderVertex and renderEdge will be called once for each vertex and edge of the to-berendered graph. At the end, the renderStop method is called. In our case, this method will output the
canvas using print. A slight complication arises when node names are longer than just one character. In this
case, the following code “centers” them on their coordinate and makes sure that they do not get overwritten
by the dots forming edges:
function BindingToASCII:renderStop()
for y=10,-30,-1 do
local t = {}
for x=-30,30 do
local s = canvas[x][y]
for i=1,#s do
pos = x+30+i-math.floor(#s/2)
if not t[pos] or t[pos] == " " or t[pos] == "." then
t[pos] = string.sub(s,i,i)
end
end
end
print(table.concat(t))
end
end
At the end, we need to return the created object:
return BindingToASCII
509
Part V
Libraries
by Till Tantau
In this part the library packages are documented. They provide additional predefined graphic objects like
new arrow heads or new plot marks, but sometimes also extensions of the basic pgf or Tik Z system. The
libraries are not loaded by default since many users will not need them.
Theoretical
Computer
Science
Theoretical
Computer
Science
Theoretical
Computer
Science
Theoretical
Computer
Science
\tikzset{
ld/.style={level distance=#1},lw/.style={line width=#1},
level 1/.style={ld=4.5mm, trunk,
lw=1ex ,sibling
level 2/.style={ld=3.5mm, trunk!80!leaf a,lw=.8ex,sibling
level 3/.style={ld=2.75mm,trunk!60!leaf a,lw=.6ex,sibling
level 4/.style={ld=2mm,
trunk!40!leaf a,lw=.4ex,sibling
level 5/.style={ld=1mm,
trunk!20!leaf a,lw=.3ex,sibling
level 6/.style={ld=1.75mm,leaf a,
lw=.2ex,sibling
}
\pgfarrowsdeclare{leaf}{leaf}
{\pgfarrowsleftextend{-2pt} \pgfarrowsrightextend{1pt}}
{
\pgfpathmoveto{\pgfpoint{-2pt}{0pt}}
\pgfpatharc{150}{30}{1.8pt}
\pgfpatharc{-30}{-150}{1.8pt}
\pgfusepathqfill
}
angle=60},
angle=56},
angle=52},
angle=48},
angle=44},
angle=40},
\newcommand{\logo}[5]
{
\colorlet{border}{#1}
\colorlet{trunk}{#2}
\colorlet{leaf a}{#3}
\colorlet{leaf b}{#4}
\begin{tikzpicture}
\scriptsize\scshape
\draw[border,line width=1ex,yshift=.3cm,
yscale=1.45,xscale=1.05,looseness=1.42]
(1,0) to [out=90, in=0]
(0,1) to [out=180,in=90] (-1,0)
to [out=-90,in=-180] (0,-1) to [out=0, in=-90] (1,0) -- cycle;
\coordinate (root) [grow cyclic,rotate=90]
child {
child [line cap=round] foreach \a in {0,1} {
child foreach \b in {0,1} {
child foreach \c in {0,1} {
child foreach \d in {0,1} {
child foreach \leafcolor in {leaf a,leaf b}
{ edge from parent [color=\leafcolor,-#5] }
} } }
} edge from parent [shorten >=-1pt,serif cm-,line cap=butt]
};
\node [align=center,below] at (0pt,-.5ex)
{ \textcolor{border}{T}heoretical \\ \textcolor{border}{C}omputer \\
\textcolor{border}{S}cience };
\end{tikzpicture}
}
\begin{minipage}{3cm}
\logo{green!80!black}{green!25!black}{green}{green!80}{leaf}\\
\logo{green!50!black}{black}{green!80!black}{red!80!green}{leaf}\\
\logo{red!75!black}{red!25!black}{red!75!black}{orange}{leaf}\\
\logo{black!50}{black}{black!50}{black!25}{}
\end{minipage}
510
39
Angle Library
Tik Z Library angles
\usetikzlibrary{angles} % LATEX and plain TEX
\usetikzlibrary[angles] % ConTEXt
This library defines pic types for drawing angles.
Pic type angle=hA i–hB i–hC i
This pic adds a drawing of an angle to the current path. This “drawing of an angle” consist of a “sector”
or “wedge” or “slice” whose pointed end is at point hB i and whose straight sides lie on the lines form
hB i to hAi and from hB i to hC i. The length of these lines is governed by the following key:
(no default, initially 5mm)
/tikz/angle radius=hdimensioni
The length of the sides of the angle’s wedge:
\tikz \draw (2,0) coordinate (A) -- (0,0) coordinate (B)
-- (-1,-1) coordinate (C)
pic [fill=black!50]
{angle = A--B--C}
pic [draw,->,red,thick,angle radius=1cm] {angle = C--B--A};
The three points hAi, hB i, and hC i must be the names of nodes or coordinates; you cannot use direct
coordinates like “(1,1)” here.
You can leave out the three points, in this case the text A--B--C is used; so in the above examples we
could just have written {angle} in the first pic.
Concerning the sector that makes up the drawing of the angle, the angular part of this sector is drawn
in front of the path if the draw option is given to the pic, while filled sector is drawn behind the pic,
provided an option like fill or shade is passed to the pic. The following example shows the difference:
\tikz \draw [line width=2mm]
(2,0) coordinate (A) -- (0,0) coordinate (B)
-- (1,1) coordinate (C)
pic [draw=blue, fill=blue!50, angle radius=1cm] {angle};
When pic text is set (which you typically do by using the quotes syntax), a node will be created whose
name is empty (and, thus, inherits the pic’s name) and which will be at the half-way angle between the
lines to hAi and hC i and whose distance from hB i is angle radius times the following factor:
/tikz/angle eccentricity=hfactor i
α
α
α
(no default, initially 0.6)
\tikz \draw (2,0) coordinate (A) -- (0,0) coordinate (B)
-- (1,1) coordinate (C)
pic ["$\alpha$", draw, ->] {angle};
\tikz \draw (2,0) coordinate (A) -- (0,0) coordinate (B)
-- (1,1) coordinate (C)
pic ["$\alpha$", draw, angle eccentricity=1] {angle};
\tikz {
\draw (2,0) coordinate (A) -- (0,0) coordinate (B)
-- (1,1) coordinate (C)
pic (alpha) ["$\alpha$", draw] {angle};
\draw (alpha) circle [radius=5pt];
}
511
40
Arrow Tip Library
The libraries arrows and arrows.spaced from older versions of pgf are still available for compatibility, but
they are considered deprecated.
The standard arrow tips, which are loaded by the library arrows.meta, are documented in Section 16.5.
512
41
Automata Drawing Library
Tik Z Library automata
\usetikzlibrary{automata} % LATEX and plain TEX
\usetikzlibrary[automata] % ConTEXt
This packages provides shapes and styles for drawing finite state automata and Turing machines.
41.1
Drawing Automata
The automata drawing library is intended to make it easy to draw finite automata and Turing machines.
It does not cover every situation imaginable, but most finite automata and Turing machines found in text
books can be drawn in a nice and convenient fashion using this library.
To draw an automaton, proceed as follows:
1. For each state of the automaton, there should be one node with the option state.
2. To place the states, you can either use absolute positions or relative positions, using options like above
or right.
3. Give a unique name to each state node.
4. Accepting and initial states are indicated by adding the options accepting and initial, respectively,
to the state nodes.
5. Once the states are fixed, the edges can be added. For this, the edge operation is most useful. It is,
however, also possible to add edges after each node has been placed.
6. For loops, use the edge [loop] operation.
Let us now see how this works for a real example. Let us consider a nondeterministic four state automaton
that checks whether an input contains the sequence 0∗ 1 or the sequence 1∗ 0.
0
q1
1
0
start
q0
q3
1
0
q2
1
\begin{tikzpicture}[shorten >=1pt,node distance=2cm,on grid,auto]
\draw[help lines] (0,0) grid (3,2);
\node[state,initial] (q_0)
\node[state]
(q_1) [above right=of q_0]
\node[state]
(q_2) [below right=of q_0]
\node[state,accepting](q_3) [below right=of q_1]
\path[->] (q_0) edge
edge
(q_1) edge
edge [loop above]
(q_2) edge
edge [loop below]
\end{tikzpicture}
{$q_0$};
{$q_1$};
{$q_2$};
{$q_3$};
node
{0} (q_1)
node [swap] {1} (q_2)
node
{1} (q_3)
node
{0} ()
node [swap] {0} (q_3)
node
{1} ();
513
41.2
States With and Without Output
The state style actually just “selects” a default underlying style. Thus, you can define multiple new complicated state style and then simply set the state style to your given style to get the desired kind of styles.
By default, the following state styles are defined:
(style, no value)
/tikz/state without output
This node style causes nodes to be drawn as circles. Also, this style calls every state.
(style, no value)
/tikz/state with output
This node style causes nodes to be drawn as split circles, that is, using the circle split shape. In the
upper part of the shape you have the name of the style, in the lower part the output is placed. To specify
the output, use the command \nodepart{lower} inside the node. This style also calls every state.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\node[state without output] {$q_0$};
q1
q0
\node[state with output] at (2,0) {$q_1$ \nodepart{lower} $00$};
\end{tikzpicture}
00
(style, initially state without output)
/tikz/state
You should redefine it to something else, if you wish to use states of a different nature.
q0
q1
11
00
\begin{tikzpicture}[state/.style=state with output]
\node[state]
{$q_0$ \nodepart{lower} $11$};
\node[state] at (2,0) {$q_1$ \nodepart{lower} $00$};
\end{tikzpicture}
(style, initially empty)
/tikz/every state
This style is used by state with output and also by state without output. By default, it does
nothing, but you can use it to make your state look more fancy:
0
q1
0
start
\begin{tikzpicture}[shorten >=1pt,node distance=2cm,on grid,>=stealth’,
every state/.style={draw=blue!50,very thick,fill=blue!20}]
\node[state,initial]
\node[state]
\node[state]
(q_0)
{$q_0$};
(q_1) [above right=of q_0] {$q_1$};
(q_2) [below right=of q_0] {$q_2$};
\path[->] (q_0) edge
edge
(q_1) edge [loop above]
(q_2) edge [loop below]
\end{tikzpicture}
q0
1
node [above left]
node [below left]
node
node
{0}
{1}
{0}
{1}
(q_1)
(q_2)
()
();
q2
1
41.3
Initial and Accepting States
The styles initial and accepting are similar to the state style as they also just select an “underlying”
style, which installs the actual settings for initial and accepting states.
Let us start with the initial states.
(style, initially initial by arrow)
/tikz/initial
This style is used to draw initial states.
514
(style, no value)
/tikz/initial by arrow
This style causes an arrow and, possibly, some text to be added to the node. The arrow points from the
text to the node. The node text and the direction and the distance can be set using the following key:
(no default, initially start)
/tikz/initial text=htexti
This key sets the text to be used. Use an empty text to suppress all text.
(no default, initially left)
/tikz/initial where=hdirectioni
Set the place where the text should be shown. Allowed values are above, below, left, and right.
(no default, initially 3ex)
/tikz/initial distance=hdistancei
Sets the length of the arrow leading from the text to the state node.
(style, initially empty)
/tikz/every initial by arrow
This style is executed at the beginning of every path that contains the arrow and the text. You
can use it to, say, make the text red or whatever.
q0
start
\begin{tikzpicture}[every initial by arrow/.style={text=red,-»}]
\node[state,initial,initial distance=2cm] {$q_0$};
\end{tikzpicture}
(style, no value)
/tikz/initial above
This is a shorthand for initial by arrow,initial where=above.
(style, no value)
/tikz/initial below
Works similarly to the previous option.
/tikz/initial left
Works similarly to the previous option.
(style, no value)
/tikz/initial right
(style, no value)
Works similarly to the previous option.
(style, no value)
/tikz/initial by diamond
This style uses a diamond to indicate an initial node.
For the accepting states, the situation is similar: There is also an accepting style that selects the way
accepting states are rendered. There are now two options: First, accepting by arrow, which works the
same way as initial by arrow, only with the direction of arrow reversed, and accepting by double,
where accepting states get a double line around them.
(style, initially accepting by double)
/tikz/accepting
This style is used to draw accepting states. You can replace this by the style accepting by arrow to
get accepting states with an arrow leaving them.
(style, no value)
/tikz/accepting by double
This style causes a double line to be drawn around a state.
(style, no value)
/tikz/accepting by arrow
This style causes an arrow and, possibly, some text to be added to the node. The arrow points to the
text from the node.
The same options as for initial states can be used, only with initial replaced by accepting:
(no default, initially empty)
/tikz/accepting text=htexti
This key sets the text to be used.
/tikz/accepting where=hdirectioni
(no default, initially right)
Set the place where the text should be shown. Allowed values are above, below, left, and right.
515
(no default, initially 3ex)
/tikz/initial distance=hdistancei
Sets the length of the arrow leading from the text to the state node.
/tikz/every accepting by arrow
(style, initially empty)
Executed at the beginning of every path that contains the arrow and the text.
0
q1
0
1
q0
q3
1
0
q2
1
\begin{tikzpicture}
[shorten >=1pt,node distance=2cm,on grid,>=stealth’,initial text=,
every state/.style={draw=blue!50,very thick,fill=blue!20},
accepting/.style=accepting by arrow]
\node[state,initial] (q_0)
\node[state]
(q_1) [above right=of q_0]
\node[state]
(q_2) [below right=of q_0]
\node[state,accepting](q_3) [below right=of q_1]
\path[->] (q_0) edge
edge
(q_1) edge
edge [loop above]
(q_2) edge
edge [loop below]
\end{tikzpicture}
node
node
node
node
node
node
{$q_0$};
{$q_1$};
{$q_2$};
{$q_3$};
[above left] {0} (q_1)
[below left] {1} (q_2)
[above right] {1} (q_3)
{0} ()
[below right] {0} (q_3)
{1} ();
(style, no value)
/tikz/accepting above
This is a shorthand for accepting by arrow,accepting where=above.
(style, no value)
/tikz/accepting below
Works similarly to the previous option.
(style, no value)
/tikz/accepting left
Works similarly to the previous option.
(style, no value)
/tikz/accepting right
Works similarly to the previous option.
41.4
Examples
In the following example, we once more typeset the automaton presented in the previous sections. This time,
we use the following rule for accepting/initial state: Initial states are red, accepting states are green, and
normal states are orange. Then, we must find a path from a red state to a green state.
516
\begin{tikzpicture}[shorten >=1pt,node distance=2cm,on grid,>=stealth’,thick,
every state/.style={fill,draw=none,orange,text=white,circular drop shadow},
accepting/.style ={green!50!black,text=white},
initial/.style
={red,text=white}]
0
q1
0
\node[state,initial] (q_0)
\node[state]
(q_1) [above right=of q_0]
\node[state]
(q_2) [below right=of q_0]
\node[state,accepting](q_3) [below right=of q_1]
1
q0
q3
1
0
q2
1
\path[->] (q_0) edge
edge
(q_1) edge
edge [loop above]
(q_2) edge
edge [loop below]
\end{tikzpicture}
node
node
node
node
node
node
[above left] {0} (q_1)
[below left] {1} (q_2)
[above right] {1} (q_3)
{0} ()
[below right] {0} (q_3)
{1} ();
The next example is the current candidate for the five-state busiest beaver:
1,1,L
qb
0,1,L
qa
start
0,1,L
1,1,R
0,1,R
qc
0,1,L
qd
1,0,R
1,0,R
1,1,R
qe
\begin{tikzpicture}[->,>=stealth’,shorten >=1pt,%
auto,node distance=2cm,on grid,semithick,
inner sep=2pt,bend angle=45]
\node[initial,state] (A)
{$q_a$};
\node[state]
(B) [above right=of A] {$q_b$};
\node[state]
(D) [below right=of A] {$q_d$};
\node[state]
(C) [below right=of B] {$q_c$};
\node[state]
(E) [below=of D]
{$q_e$};
\path [every node/.style={font=\footnotesize}]
(A) edge
node {0,1,L} (B)
edge
node {1,1,R} (C)
(B) edge [loop above] node {1,1,L} (B)
edge
node {0,1,L} (C)
(C) edge
node {0,1,L} (D)
edge [bend left] node {1,0,R} (E)
(D) edge [loop below] node {1,1,R} (D)
edge
node {0,1,R} (A)
(E) edge [bend left] node {1,0,R} (A);
\end{tikzpicture}
517
{$q_0$};
{$q_1$};
{$q_2$};
{$q_3$};
42
Babel Library
Tik Z Library babel
\usepgflibrary{babel}
\usepgflibrary[babel]
\usetikzlibrary{babel}
\usetikzlibrary[babel]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
A tiny library that make the interaction with the babel package easier. Despite the name, it may also
be useful in other contexts, namely whenever the catcodes of important symbols are changed globally.
Normally, using this library is always a good idea; it is not always loaded by default since in some rare
cases it may break old code.
The problems this library tries to fix have to do with the so-called “catcodes” of symbols used inside
Tik Z. In normal TEX operation, symbols like ! or " are “normal” characters and the Tik Z parser expects
them to be. Some packages, most noticably the babel package, agressively change these character codes so
that for instance a semicolon gets a little extra space in french mode or a quotation mark followed by a
vertical bar breaks ligatures in german mode.
Unfortunately, Tik Z expects the character codes of some symbols to be “normal.” In some important
cases it will tolerate changed character codes, but when the changes made by babel (or some other package)
are too “aggressive,” compilation of Tik Z code will fail.
The babel library of Tik Z is intended to help out in this situation. All this library does is to set the
following two keys to true. You can, however, also set these keys directly and also switch them off or on
individually and independently of this library.
/tikz/handle active characters in code=htrue or falsei
(no default, initially false)
When this key is set, at the beginning of every \tikz command and every {tikzpicture}, the character
codes of all symbols used by Tik Z are reset to their normal values. Furthermore, at the beginning of
each node, the catcodes are restored to the values they had prior to the current picture.
The net effect of this is that, in most cases, symbols having a special character code can be used nicely
both in Tik Z code and also in node texts.
In the following, slightly silly, example we make the dot an active character and define it in some
strange way. Now, in the later Tik Z command, the dot in 3.0cm may no longer be active and setting
the handle... option achieves exactly this. However, as can be seen, the dot is once more active inside
the node.
hallø peøple
\catcode‘\.=\active
\def.{\o}
\tikz [handle active characters in code]
\node [draw, minimum width=3.0cm] {hall. pe.ple};
/tikz/handle active characters in nodes=htrue or falsei
(no default, initially false)
This key is needed for a special situation: As explained for the handle ... code key, that key switches
off all special meaning of symbols and switches them back on again at the beginning of nodes. However,
there is one situation when this is not possible: When some text has already been read by TEX, the
catcodes can no longer change. Now, for normal nodes this is not a problem since their contents has
not been read at the moment the catcodes are restored. In contrast for label nodes for edges, nodes
produced by the graph and quotes libraries, and some others nodes, their text has already been read
when the catcodes get adjusted.
The present key may help in such situations: It causes the text of all such “indirectly created” nodes to
be surrounded by a call to the \scantokens command. This command attempts to reread an already
read text, but allows catcodes to change. As users of this command will know, it is not a perfect
substitute for directly reading the text by TEX, but it normally has the desired effect.
føø
hallø peøple
\catcode‘\.=\active
\def.{\o}
\tikz [handle active characters in code,
handle active characters in nodes]
\node [draw, label=f..] {hall. pe.ple};
518
43
Background Library
Tik Z Library backgrounds
\usetikzlibrary{backgrounds} % LATEX and plain TEX
\usetikzlibrary[backgrounds] % ConTEXt
This library defines “backgrounds” for pictures. This does not refer to background pictures, but rather
to frames drawn around and behind pictures. For example, this package allows you to just add the
framed option to a picture to get a rectangular box around your picture or gridded to put a grid
behind your picture.
The first use of this library is to make the following key available:
(no default)
/tikz/on background layer=hoptionsi
This key can (only) be used with a {scope} or \scoped. It will cause everything inside the scope to be
typeset on a background layer.
The hoptionsi will be executed inside background scope. This is useful since other options passed to
the {scope} environment will be executed before the actual background material starts and, thus, will
have no effect on it.
\begin{tikzpicture}
% On main layer:
\fill[blue] (0,0) circle (1cm);
\begin{scope}[on background layer={color=yellow}]
\fill (-1,-1) rectangle (1,1);
\end{scope}
\begin{scope}[on background layer]
\fill[black] (-.8,-.8) rectangle (.8,.8);
\end{scope}
% On main layer again:
\fill[blue!50] (-.5,-1) rectangle (.5,1);
\end{tikzpicture}
A scope with this option set should not be “deeply nested” inside the picture since changes to the graphic
state (like the color or the transformation matrix) “do not survive a layer switch,” see also Section 108
for details. In particular, setting, say, the line width at the beginning of a picture will not have an effect
on the background picture.
For this reason, it may be useful to setup the following style:
(style, no value)
/tikz/every on background layer
This style is executed at the beginning of each background layer. If you have a global setup in
every picture, you should consider putting that part of it that concerns the graphics state into
this style.
\tikzset{
every picture/.style={line width=1ex},
every on background layer/.style={every picture}
}
\begin{tikzpicture}
\draw [->] (0,0) -- (2,1);
\scoped[on background layer]
\draw[red] (0,1) -- (2,0);
\end{tikzpicture}
When this package is loaded, the following styles become available:
(style, no value)
/tikz/show background rectangle
This style causes a rectangle to be drawn behind your graphic. This style option must be given to the
{tikzpicture} environment or to the \tikz command.
519
\begin{tikzpicture}[show background rectangle]
\draw (0,0) ellipse (10mm and 5mm);
\end{tikzpicture}
The size of the background rectangle is determined as follows: We start with the bounding box of the
picture. Then, a certain separator distance is added on the sides. This distance can be different for the
x- and y-directions and can be set using the following options:
(no default, initially 1ex)
/tikz/inner frame xsep=hdimensioni
Sets the additional horizontal separator distance for the background rectangle.
(no default, initially 1ex)
/tikz/inner frame ysep=hdimensioni
Same for the vertical separator distance.
(no default)
/tikz/inner frame sep=hdimensioni
Sets the horizontal and vertical separator distances simultaneously.
The following two styles make setting the inner separator a bit easier to remember:
(style, no value)
/tikz/tight background
Sets the inner frame separator to 0pt. The background rectangle will have the size of the bounding
box.
(style, no value)
/tikz/loose background
Sets the inner frame separator to 2ex.
You can influence how the background rectangle is rendered by setting the following style:
/tikz/background rectangle
(style, initially draw)
This style dictates how the background rectangle is drawn or filled. The default setting causes
the path of the background rectangle to be drawn in the usual way. Setting this style to, say,
fill=blue!20 causes a light blue background to be added to the picture. You can also use more
fancy settings as shown in the following example:
\begin{tikzpicture}
[background rectangle/.style=
{double,ultra thick,draw=red,top color=blue,rounded corners},
show background rectangle]
\draw (0,0) ellipse (10mm and 5mm);
\end{tikzpicture}
Naturally, no one in their right mind would use the above, but here is a nice background:
\begin{tikzpicture}
[background rectangle/.style=
{draw=blue!50,fill=blue!20,rounded corners=1ex},
show background rectangle]
\draw (0,0) ellipse (10mm and 5mm);
\end{tikzpicture}
/tikz/framed
This is a shorthand for show background rectangle.
(style, no value)
/tikz/show background grid
(style, no value)
This style behaves similarly to the show background rectangle style, but it will not use a rectangle
path, but a grid. The lower left and upper right corner of the grid is computed in the same way as for
the background rectangle:
\begin{tikzpicture}[show background grid]
\draw (0,0) ellipse (10mm and 5mm);
\end{tikzpicture}
You can influence the background grid by setting the following style:
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(style, initially draw,help lines)
/tikz/background grid
This style dictates how the background grid path is drawn.
\begin{tikzpicture}
[background grid/.style={thick,draw=red,step=.5cm},
show background grid]
\draw (0,0) ellipse (10mm and 5mm);
\end{tikzpicture}
This option can be combined with the framed option (use the framed option first):
\tikzset{background grid/.style={thick,draw=red,step=.5cm},
background rectangle/.style={rounded corners,fill=yellow}}
\begin{tikzpicture}[framed,gridded]
\draw (0,0) ellipse (10mm and 5mm);
\end{tikzpicture}
(style, no value)
/tikz/gridded
This is a shorthand for show background grid.
(style, no value)
/tikz/show background top
This style causes a single line to be drawn at the top of the background rectangle. Normally, the line
coincides exactly with the top line of the background rectangle:
\begin{tikzpicture}[
background rectangle/.style={fill=yellow},
framed,show background top]
\draw (0,0) ellipse (10mm and 5mm);
\end{tikzpicture}
The following option allows you to lengthen (or shorten) the line:
(no default, initially 0pt)
/tikz/outer frame xsep=hdimensioni
The hdimensioni is added at the left and right side of the line.
\begin{tikzpicture}
[background rectangle/.style={fill=yellow},
framed,
show background top,
outer frame xsep=1ex]
\draw (0,0) ellipse (10mm and 5mm);
\end{tikzpicture}
(no default, initially 0pt)
/tikz/outer frame ysep=hdimensioni
This option does not apply to the top line, but to the left and right lines, see below.
(no default)
/tikz/outer frame sep=hdimensioni
Sets both the x- and y-separation.
\begin{tikzpicture}
[background rectangle={fill=blue!20},
outer frame sep=1ex,%
show background top,%
show background bottom,%
show background left,%
show background right]
\draw (0,0) ellipse (10mm and 5mm);
\end{tikzpicture}
You can influence how the line is drawn grid by setting the following style:
(style, initially draw)
/tikz/background top
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\tikzset{background rectangle/.style={fill=blue!20},
background top/.style={draw=blue!50,line width=1ex}}
\begin{tikzpicture}[framed,show background top]
\draw (0,0) ellipse (10mm and 5mm);
\end{tikzpicture}
(style, no value)
/tikz/show background bottom
Works like the style for the top line.
(style, no value)
/tikz/show background left
Works similarly.
(style, no value)
/tikz/show background right
Works similarly.
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44
Calc Library
Tik Z Library calc
\usetikzlibrary{calc} % LATEX and plain TEX
\usetikzlibrary[calc] % ConTEXt
The library allows advanced Coordinate Calculations. It is documented in all detail in Section 13.5 on
page 142.
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45
Calendar Library
Tik Z Library calendar
\usetikzlibrary{calendar} % LATEX and plain TEX
\usetikzlibrary[calendar] % ConTEXt
The library defines the \calendar command, which can be used to typeset calendars. The command
relies on the \pgfcalendar command from the pgfcalendar package, which is loaded automatically.
The \calendar command is quite configurable, allowing you to produce all kinds of different calendars.
45.1
Calendar Command
The core command for creating calendars in Tik Z is the \calendar command. It is available only inside
{tikzpicture} environments (similar to, say, the \draw command).
\calendarhcalendar specificationi;
The syntax for this command is similar to commands like \node or \matrix. However, it has its
complete own parser and only those commands described in the following will be recognized, nothing
else. Note, furthermore, that a hcalendar specificationi is not a path specification, indeed, no path is
created for the calendar.
The specification syntax. The hcalendar specificationi must be a sequence of elements, each of which
has one of the following structures:
• [hoptionsi]
You provide hoptionsi in square brackets as in [red,draw=none]. These hoptionsi can be any Tik Z
option and they apply to the whole calendar. You can provide this element multiple times, the
effect accumulates.
• (hnamei)
This has the same effect as saying [name=hnamei]. The effect of providing a hnamei is explained
later. Note already that a calendar is not a node and the hnamei is not the name of a node.
• at (hcoordinatei)
This has the same effect as saying [at=(hcoordinatei)].
• if (hdate conditioni) hoptions or commandsielsehelse options or commandsi
The effect of such an if is explained later.
At the beginning of every calendar, the following style is used:
(style, initially empty)
/tikz/every calendar
This style is used with every calendar.
The date range. The overall effect of the \calendar command is to execute code for each day of a
range of dates. This range of dates is set using the following option:
/tikz/dates=hstart dateitohend datei
(no default)
This option specifies the date range. Both the start and end date are specified as described on
page 906. In short: You can provide ISO-format type dates like 2006-01-02, you can replace the day
of month by last to refer to the last day of a month (so 2006-02-last is the same as 2006-02-28),
and you can add a plus sign followed by a number to specify an offset (so 2006-01-01+-1 is the
same as 2005-12-31).
It will be useful to fix two pieces of terminology for the following descriptions: The \calendar command
iterates over the dates in the range. The current date refers to the current date the command is
processing as it iterates over the dates. For each current date code is executed, which will be called the
current date code. The current date code consists of different parts, to be detailed later.
The central part of the current date code is the execution of the code \tikzdaycode. By default, this
code simply produces a node whose text is set to the day of month. This means that unless further
action is taken, all days of a calendar will be put on top of each other! To avoid this, you must modify the
current date code to shift days around appropriately. Predefined arrangements like day list downward
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or week list do this for you, but you can define arrangements yourself. Since defining an arrangement
is a bit tricky, it is explained only later on. For the time being, let us use a predefined arrangement to
produce our first calendar:
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\tikz \calendar[dates=2000-01-01 to 2000-01-31,week list];
Changing the spacing. In the above calendar, the spacing between the days is determined by numerous options. Most arrangements do not use all of these options, but only those that apply naturally.
(no default, initially 3.5ex)
/tikz/day xshift=hdimensioni
Specifies the horizontal shift between days. This is not the gap between days, but the shift between
the anchors of their nodes.
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\tikz \calendar[dates=2000-01-01 to 2000-01-31,week list,day xshift=3ex];
(no default, initially 3ex)
/tikz/day yshift=hdimensioni
Specifies the vertical shift between days. Again, this is the shift between the anchors of their
nodes.
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\tikz \calendar[dates=2000-01-01 to 2000-01-31,week list,day yshift=2ex];
(no default)
/tikz/month xshift=hdimensioni
Specifies an additional horizontal shift between different months.
(no default)
/tikz/month yshift=hdimensioni
Specifies an additional vertical shift between different months.
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\tikz \calendar[dates=2000-01-01 to 2000-02-last,week list,
month yshift=0pt];
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\tikz \calendar[dates=2000-01-01 to 2000-02-last,week list,
month yshift=1cm];
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Changing the position of the calendar. The calendar is placed in such a way that, normally, the
anchor of the first day label is at the origin. This can be changed by using the at option. When you
say at={(1,1)}, this anchor of the first day will lie at coordinate (1, 1).
In general, arrangements will not always place the anchor of the first day at the origin. Sometimes,
additional spacing rules get in the way. There are different ways of addressing this problem: First, you
can just ignore it. Since calendars are often placed in their own {tikzpicture} and since their size if
computed automatically, the exact position of the origin often does not matter at all. Second, you can
put the calendar inside a node as in ...node {\tikz \calendar...}. This allows you to position the
node in the normal ways using the node’s anchors. Third, you can be very clever and use a single-cell
matrix. The advantage is that a matrix allows you to provide any anchor of any node inside the matrix
as an anchor for the whole matrix. For example, the following calendar is placed in such a way the
center of 2000-01-20 lies on the position (2, 2):
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\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\matrix [anchor=cal-2000-01-20.center] at (2,2)
{ \calendar(cal)[dates=2000-01-01 to 2000-01-31,week list]; \\};
\end{tikzpicture}
Unfortunately, the matrix-base positions, which is the cleanest way, isn’t as portable as the other
approaches (it currently does not work with the svg backend for instance).
Changing the appearance of days. As mentioned before, each day in the above calendar is produced
by an execution of the \tikzdaycode. Each time this code is executed, the coordinate system will have
been set up appropriately to place the day of the month correctly. You can change both the code and
its appearance using the following options.
(no default, initially see below)
/tikz/day code=hcodei
This option allows you to change the code that is executed for each day. The default is to create a
node with an appropriate name, but you can change this:
\tikz \calendar[dates=2000-01-01 to 2000-01-31,week list,
day code={\fill[blue] (0,0) circle (2pt);}];
The default code is the following:
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\node[name=\pgfcalendarsuggestedname,every day]{\tikzdaytext};
The first part causes the day nodes to be accessible via the following names: If hnamei is the
name given to the calendar via a name= option or via the specification element (hnamei), then
\pgfcalendarsuggestedname will expand to hnamei-hdatei, where hdatei is the date of the day
that is currently being processed in ISO format .
For example, if January 1, 2006 is being processed and the calendar has been named mycal, then
the node containing the 1 for this date will be names mycal-2006-01-01. You can later reference
this node.
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\begin{tikzpicture}
\calendar (mycal) [dates=2000-01-01 to 2000-01-31,week list];
\draw[red] (mycal-2000-01-20) circle (4pt);
\end{tikzpicture}
(no default)
/tikz/day text=htexti
This option changes the setting of the \tikzdaytext. By default, this macro simply yields the
current day of month, but you can change it arbitrarily. Here is a silly example:
x
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x
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x
x
x
x
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\tikz \calendar[dates=2000-01-01 to 2000-01-31,week list,
day text=x];
More useful examples are based on using the \% command. This command is redefined inside a
\pgfcalendar to mean the same as \pgfcalendarshorthand. (The original meaning of \% is lost
inside the calendar, you need to save if before the calendar if you really need it.)
The \% inserts the current day/month/year/day of week in a certain format into the text. The
first letter following the \% selects the type (permissible values are d, m, y, w), the second letter
specifies how the value should be displayed (- means numerically, = means numerically with leading
space, 0 means numerically with leading zeros, t means textual, and . means textual, abbreviated). For example \%d0 gives the day with a leading zero (for more details see the description of
\pgfcalendarshorthand on page 911).
Let us redefine the day text so that it yields the day with a leading zero:
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\tikz \calendar[dates=2000-01-01 to 2000-01-31,week list,
day text=\%d0];
/tikz/every day (initially anchor=base east)
(no default)
This style is executed by the default node code for each day. The every day style is useful for
changing the way days look. For example, let us make all days red:
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\tikz[every day/.style=red]
\calendar[dates=2000-01-01 to 2000-01-31,week list];
Changing the appearance of month and year labels. In addition to the days of a calendar, labels
for the months and even years (for really long calendars) can be added. These labels are only added
once per month or year and this is not done by default. Rather, special styles starting with month
label place these labels and make them visible:
\tikz \calendar[dates=2000-01-01 to 2000-02-last,week list,
month label above centered];
January
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February
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The following options change the appearance of the month and year label:
(no default, initially see below)
/tikz/month code=hcodei
This option allows you to specify what the macro \tikzmonthcode should expand to.
By default, the \tikzmonthcode it is set to
\node[every month]{\tikzmonthtext};
Note that this node is not named by default.
(no default)
/tikz/month text=htexti
This option allows you to change the macro \tikzmonthtext. By default, the month text is a long
textual presentation of the current month being typeset.
January 2000
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\tikz \calendar[dates=2000-01-01 to 2000-01-31,week list,
month label above centered,
month text=\textcolor{red}{\%mt} \%y-];
(style, initially empty)
/tikz/every month
This style can be used to change the appearance of month labels.
(no default)
/tikz/year code=hcodei
Works like month code, only for years.
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(no default)
/tikz/year text=htexti
Works like month text, only for years.
(no value)
/tikz/every year
Works like every month, only for years.
Date ifs. Much of the power of the \calendar command comes from the use of conditionals. There
are two equivalent way of specifying such a conditional. First, you can add the text if (hconditionsi)
hcode or optionsi to your hcalendar specificationi, possibly followed by elsehelse code or optionsi. You
can have multiple such conditionals (but you cannot nest them in this simple manner). The second way
is to use the following option:
/tikz/if=(hconditionsi)hcode or optionsielsehelse code or optionsi
(no default)
This option has the same effect as giving a corresponding if in the hcalendar specificationi. The
option is mostly useful for use in the every calendar style, where you cannot provide if conditionals
otherwise.
Now, regardless of how you specify a conditional, it has the following effect (individually and independently for each date in the calendar):
1. It is checked whether the current date is one of the possibilities listed in hconditionsi. An example
of such a condition is Sunday. Thus, when you write if (Saturday,Sunday) {foo}, then foo will
be executed for every day in the calendar that is a Saturday or a Sunday.
The command \ifdate and, thereby, \pgfcalendarifdate are used to evaluate the hconditionsi,
see page 907 for a complete list of possible tests. The most useful tests are: Tests like Monday
and so on, workday for the days Monday to Friday, weekend for Saturday and Sunday, equals for
testing whether the current date equals a given date, at least and at least for comparing the
current date with a given date.
2. If the date passes the check, the hcode or optionsi is evaluated in a manner to be described in a
moment; if the date fails, the helse code or optionsi is evaluated, if present.
The hcode or optionsi can either be some code. This is indicated by surrounding the code with
curly braces. It can also be a list of Tik Z options. This is indicated by surrounding the options
with square brackets. For example in the date test if (Sunday) {\draw...} else {\fill...}
there are two pieces of code involved. By comparison, if (Sunday) [red] else [green] involves
two options.
If hcode or optionsi is code, it is simply executed (for the current day). If it is a list of options,
these options are passed to a scope surrounding the current date.
Let us now have a look at some examples. First, we use a conditional to make all Sundays red.
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\tikz
\calendar
[dates=2000-01-01 to 2000-01-31,week list]
if (Sunday) [red];
Next, let us do something on a specific date:
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\tikz
\calendar
[dates=2000-01-01 to 2000-01-31,week list]
if (Sunday)
[red]
if (equals=2000-01-20) {\draw (0,0) circle (8pt);};
You might wonder why the circle seems to be “off” the date. Actually, it is centered on the date, it is
just that the date label uses the base east anchor, which shifts the label up and right. To overcome
this problem we can change the anchor:
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\tikz [every day/.style={anchor=mid}]
\calendar
[dates=2000-01-01 to 2000-01-31,week list]
if (Sunday)
[red]
if (equals=2000-01-20) {\draw (0,0) circle (8pt);};
However, the single day dates are now no longer aligned correctly. For this, we can change the day text
to \%d=, which adds a space at the beginning of single day text.
In the following, more technical information is covered. Most readers may wish to skip it.
The current date code. As mentioned earlier, for each date in the calendar the current date code is
executed. It is the job of this code to shift around date nodes, to render the date nodes, to draw the
month labels and to do all other stuff that is necessary to draw a calendar.
The current date code consists of the following parts, in this order:
1. The before-scope code.
2. A scope is opened.
3. The at-begin-scope code.
4. All date-ifs from the hcalendar specificationi are executed.
5. The at-end-scope code.
6. The scope is closed.
7. The after-scope code.
All of the codes mentioned above can be changed using appropriate options, see below. In case you
wonder why so many are needed, the reason is that the current date code as a whole is not surrounded
by a scope or TEX group. This means that code executed in the before-scope code and in the after-scope
code has an effect on all following days. For example, if the after-scope code modifies the transformation
matrix by shifting everything downward, all following days will be shifted downward. If each day does
this, you get a list of days, one below the other.
However, you do not always want code to have an effect on everything that follows. For instance, if a
day has the date-if if (Sunday) [red], we only want this Sunday to red, not all following days also.
Similarly, sometimes it is easier to compute the position of a day relative to a fixed origin and we do
not want any modifications of the transformation matrix to have an effect outside the scope.
By cleverly adjusting the different codes, all sorts of different day arrangements are possible.
(no default)
/tikz/execute before day scope=hcodei
The hcodei is executed before everything else for each date. Multiple calls of this option have an
accumulative effect. Thus, if you use this option twice, the code from the first use is used first for
each day, followed by the code given the second time.
(no default)
/tikz/execute at begin day scope=hcodei
This code is execute before everything else inside the scope of the current date. Again, the effect
is accumulative.
(no default)
/tikz/execute at end day scope=hcodei
This code is executed just before the day scope is closed. The effect is also accumulative, however,
in reverse order. This is useful to pair, say, \scope and \endscope commands in at-begin- and
at-end-code.
(no default)
/tikz/execute after day scope=hcodei
This is executed at the very end of the current date, outside the scope. The accumulation is also
in reverse.
In the rest of the following subsections we have a look at how the different scope codes can be used to
create different calendar arrangements.
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45.1.1
Creating a Simple List of Days
We start with a list of the days of the calendar, one day below the other. For this, we simply shift the
coordinate system downward at the end of the code for each day. This shift must be outside the day scope
as we want day shifts to accumulate. Thus, we use the following code:
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\tikz
\calendar [dates=2000-01-01 to 2000-01-08,
execute after day scope=
{\pgftransformyshift{-1em}}];
Clearly, we can use this approach to create day lists going up, down, right, left, or even diagonally.
45.1.2
Adding a Month Label
We now want to add a month label to the left of the beginning of each month. The idea is to do two things:
1. We add code that is executed only on the first of each month.
2. The code is executed before the actual day is rendered. This ensures that options applying to the days
do not affect the month rendering.
We have two options where we should add the month code: Either we add it at the beginning of the day
scope or before. Either will work fine, but it might be safer to put the code inside the scope to ensure that
settings to not inadvertently “leak outside.”
January
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\tikz
\calendar
[dates=2000-01-01 to 2000-01-08,
execute after day scope={\pgftransformyshift{-1em}},
execute at begin day scope=
{\ifdate{day of month=1}{\tikzmonthcode}{}},
every month/.append style={anchor=base east,xshift=-2em}];
In the above code we used the \ifdate{hconditioni}{hthen codei}{helse codei} command, which is
described on page 909 in detail and which has much the same effect as if (hconditioni){hthen codei} else
{helse codei}, but works in normal code.
45.1.3
Creating a Week List Arrangement
Let us now address a more complicated arrangement: A week list. In this arrangement there is line for each
week. The horizontal placement of the days is thus that all Mondays lie below each other, likewise for all
Tuesdays, and so on.
In order to typeset this arrangement, we can use the following approach: The origin of the coordinate
system rests at the anchor for the Monday of each week. That means that at the end of each week the origin
is moved downward one line. On all other days, the origin at the end of the day code is the same as at
the beginning. To position each day correctly, we use code inside and at the beginning of the day scope to
horizontally shift the day according to its day of week.
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\tikz
\calendar
[dates=2000-01-01 to 2000-01-20,
% each day is shifted right according to the day of week
execute at begin day scope=
{\pgftransformxshift{\pgfcalendarcurrentweekday em}},
% after each week, the origin is shifted downward:
execute after day scope=
{\ifdate{Sunday}{\pgftransformyshift{-1em}}{}}];
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45.1.4
Creating a Month List Arrangement
For another example, let us create an arrangement that contains one line for each month. This is easy
enough to do as for weeks, unless we add the following requirement: Again, we want all days in a column to
have the same day of week. Since months start on different days of week, this means that each row has to
have an individual offset.
One possible way is to use the following approach: After each month (or at the beginning of each month)
we advance the vertical position of the offset by one line. For horizontal placement, inside the day scope we
locally shift the day by its day of month. Furthermore, we must additionally shift the day to ensure that
the first day of the month lies on the correct day of week column. For this, we remember this day of week
the first time we see it.
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\newcount\mycount
\tikz
\calendar
[dates=2000-01-01 to 2000-02-last,
execute before day scope=
{
\ifdate{day of month=1} {
% Remember the weekday of first day of month
\mycount=\pgfcalendarcurrentweekday
% Shift downward
\pgftransformyshift{-1em}
}{}
},
execute at begin day scope=
{
% each day is shifted right according to the day of month
\pgftransformxshift{\pgfcalendarcurrentday em}
% and additionally according to the weekday of the first
\pgftransformxshift{\the\mycount em}
}];
45.2
Arrangements
An arrangement specifies how the days of calendar are arranged on the page. The calendar library defines
a number of predefined arrangements.
We start with arrangements in which the days are listed in a long line.
(style, no value)
/tikz/day list downward
This style causes the days of a month to be typeset one below the other. The shift between days is
given by day yshift. Between month an additional shift of month yshift is added.
28
29
30
31
\tikz
\calendar [dates=2000-01-28 to 2000-02-03,
day list downward,month yshift=1em];
1
2
3
(style, no value)
/tikz/day list upward
works as above, only the list grows upward instead of downward.
532
\tikz
\calendar [dates=2000-01-28 to 2000-02-03,
day list upward,month yshift=1em];
3
2
1
31
30
29
28
(style, no value)
/tikz/day list right
This style also works as before, but the list of days grows to the right. Instead of day yshift and
month yshift, the values of day xshift and month xshift are used.
28 29 30 31
1
2
3
\tikz
\calendar [dates=2000-01-28 to 2000-02-03,
day list right,month xshift=1em];
(style, no value)
/tikz/day list left
As above, but the list grows left.
The next arrangement lists days by the week.
(style, no value)
/tikz/week list
This style creates one row for each week in the range. The value of day xshift is used for the distance
between days in each week row, the value of day yshift is used for the distance between rows. In both
cases, “distance” refers to the distance between the anchors of the nodes of the days (or, more generally,
the distance between the origins of the little pictures created for each day).
The days inside each week are shifted such that Monday is always at the first position (to change this,
you need to copy and then modify the code appropriately). If the date range does not start on a Monday,
the first line will not start in the first column, but rather in the column appropriate for the first date in
the range.
At the beginning of each month (except for the first month in the range) an additional vertical space of
month yshift is added. If this is set to 0pt you get a continuous list of days.
3 4 5 6 7
10 11 12 13 14
17 18 19 20 21
24 25 26 27 28
31
1 2
8 9
15 16
22 23
29 30
\tikz
\calendar [dates=2000-01-01 to 2000-02-last,week list];
1 2 3 4 5 6
7 8 9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29
533
3
10
17
24
31
7
14
21
28
4
11
18
25
1
8
15
22
29
5
12
19
26
2
9
16
23
6
13
20
27
3
10
17
24
7
14
21
28
4
11
18
25
1
8
15
22
29
5
12
19
26
\tikz
\calendar [dates=2000-01-01 to 2000-02-last,week list,
month yshift=0pt];
2
9
16
23
30
6
13
20
27
The following arrangement gives a very compact view of a whole year.
(style, no value)
/tikz/month list
In this arrangement there is a row for each month. As for the week list, the day xshift is used for
the horizontal distance. For the vertical shift, month yshift is used.
In each row, all days of the month are listed alongside each other. However, it is once more ensured that
days in each column lie on the same day of week. Thus, the very first column contains only Mondays.
If a month does not start with a Monday, its days are shifted to the right such that the days lie on the
correct columns.
January
February
March
April
May
June
July
August
September
October
November
December
1
1
2
1
2
1
3
2
4
3
3
4
1
5
2
3
4
1
1
5
4
1
6
3
1
5
2
3
1
4
2
2
1
2
2
6
5
2
7
4
2
6
3
1
5
3
3
7
6
3
8
5
3
7
4
2
6
4
4 5 6 7
8 9 10 11
7 8 9 10
4 5 6 7
9 10 11 12
6 7 8 9
4 5 6 7
8 9 10 11
5 6 7 8
3 4 5 6
7 8 9 10
5 6 7 8
8
12
11
8
13
10
8
12
9
7
11
9
9
13
12
9
14
11
9
13
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8
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14
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10
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14
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9
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21
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17
21
19
19
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22
19
24
21
19
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20
18
22
20
20
24
23
20
25
22
20
24
21
19
23
21
21
25
24
21
26
23
21
25
22
20
24
22
22
26
25
22
27
24
22
26
23
21
25
23
23
27
26
23
28
25
23
27
24
22
26
24
24
28
27
24
29
26
24
28
25
23
27
25
25
29
28
25
30
27
25
29
26
24
28
26
26 27 28 29 30 31
29
26
31
28
26
30
27
25
29
27
30 31
27 28 29 30
29
27
31
28
26
30
28
30
28 29 30 31
29 30
27 28 29 30 31
29 30 31
\sffamily\scriptsize
\tikz
\calendar [dates=2000-01-01 to 2000-12-31,
month list,month label left,month yshift=1.25em]
if (Sunday) [black!50];
45.3
Month Labels
For many calendars you may wish to add a label to each month. We have already covered how month nodes
are created and rendered in the description of the \calendar command: use month text, every month, and
also month code (if necessary) to change the appearance of the month labels.
What we have not yet covered is where these labels are placed. By default, they are not placed at all as
there is no good “default position” for them. Instead, you can use one of the following options to specify a
position for the labels:
(style, no value)
/tikz/month label left
Places the month label to the left of the first day of the month. (For week list and month list where
a month does not start on a Monday, the position is chosen “as if” the month had started on a Monday
– which is usually exactly what you want.)
534
28
29
30
31
February
\tikz
\calendar [dates=2000-01-28 to 2000-02-03,
day list downward,month yshift=1em,
month label left];
1
2
3
(style, no value)
/tikz/month label left vertical
This style works like the above style, only the label is rotated counterclockwise by 90 degrees.
February
28
29
30
31
\tikz
\calendar [dates=2000-01-28 to 2000-02-03,
day list downward,month yshift=1em,
month label left vertical];
1
2
3
(style, no value)
/tikz/month label right
This style places the month label to the right of the row in which the first day of the month lies. This
means that for a day list the label is to the right of the first day, for a week list it is to the right of the
first week, and for a month list it is to the right of the whole month.
\tikz
\calendar [dates=2000-01-28 to 2000-02-03,
day list downward,month yshift=1em,
month label right];
28
29
30
31
1
2
3
February
(style, no value)
/tikz/month label right vertical
Works as above, only the label is rotated clockwise by 90 degrees.
\tikz
\calendar [dates=2000-01-28 to 2000-02-03,
day list downward,month yshift=1em,
month label right vertical];
28
29
30
31
February
1
2
3
(style, no value)
/tikz/month label above left
This style places the month label above of the row of the first day, flushed left to the leftmost column.
The amount by which the label is raised is fixed to 1.25em; use the yshift option with the month node
to modify this.
535
February
28 29 30 31
1
2
3
\tikz
\calendar [dates=2000-01-28 to 2000-02-03,
day list right,month xshift=1em,
month label above left];
\tikz
\calendar [dates=2000-01-20 to 2000-02-10,
week list,month label above left];
20 21 22 23
24 25 26 27 28 29 30
31
February
1
8
7
2 3
9 10
4
5
6
(style, no value)
/tikz/month label above centered
works as above, only the label is centered above the row containing the first day.
February
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
\tikz
\calendar [dates=2000-02-01 to 2000-02-last,
day list right,month label above centered];
\tikz
\calendar [dates=2000-01-20 to 2000-02-10,
week list,month label above centered];
20 21 22 23
24 25 26 27 28 29 30
31
February
1
8
7
2 3
9 10
4
5
6
(style, no value)
/tikz/month label above right
works as above, but flushed right
\tikz
\calendar [dates=2000-01-20 to 2000-02-10,
week list,month label above right];
20 21 22 23
24 25 26 27 28 29 30
31
February
1
8
7
2 3
9 10
4
5
6
(style, no value)
/tikz/month label below left
Works like month label above left, only the label is placed below the row. This placement is not
really useful with the week list arrangement, but rather with the day list right or month list
arrangement.
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
February
536
\tikz
\calendar [dates=2000-02-01 to 2000-02-last,
day list right,month label below left];
(style, no value)
/tikz/month label below centered
Works like month label above centered, only below.
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
February
\tikz
\calendar [dates=2000-02-01 to 2000-02-last,
day list right,month label below centered];
45.4
Examples
In the following, some example calendars are shown that come either from real applications or are just nice
to look at.
Let us start with a year-2100-countdown, in which we cross out dates as we approach the big celebration.
For this, we set the shape to strike out for these dates.
December 2099
1 2 3 4 5 6
7 8 9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30 31
January 2100
4 5 6 7
11 12 13 14
18 19 20 21
25 26 27 28
\begin{tikzpicture}
\calendar
[
dates=2099-12-01 to 2100-01-last,
week list,inner sep=2pt,month label above centered,
month text=\%mt \%y0
]
if (at most=2099-12-29) [nodes={strike out,draw}]
if (weekend)
[black!50,nodes={draw=none}]
;
\end{tikzpicture}
1 2 3
8 9 10
15 16 17
22 23 24
29 30 31
The next calendar shows a deadline, which is 10 days in the future from the current date. The last three
days before the deadline are in red, because we really should be done by then. All days on which we can no
longer work on the project are crossed out.
4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
31
September 2015
1 2 3 4 5 6
7 8 9 10 11 12 13
14 15 16 17 18 19 20
21 22 23
\begin{tikzpicture}
\calendar
[
dates=\year-\month-\day+-25 to \year-\month-\day+25,
week list,inner sep=2pt,month label above centered,
month text=\textit{\%mt \%y0}
]
if (at least=\year-\month-\day) {}
else [nodes={strike out,draw}]
if (at most=\year-\month-\day+7)
[green!50!black]
if (between=\year-\month-\day+8 and \year-\month-\day+10)
[red]
if (Sunday)
[gray,nodes={draw=none}]
;
\end{tikzpicture}
The following example is a futuristic calendar that is all about circles:
537
1 2 3
31
4
30
5
29
6
28
7
1 2 3
1 2 3
27
31
4
4
8
30
30
5
5
26
9
29
29
6
6
25
10
28
28
7
7
24
27
27
11
8
8
23
12
26
26
9
9
22
13
25
25
21
10
10
14
20
15
24
24
19
11
11
18 17 16
23
23
12
12
22
22
13
13
1 2 3
1 2 3
21
21
14
14
31
4
4
20
20
30
30
19 18 17 1615
19 18 17 1615
5
5
29
29
6
6
28
28
7
7
27
27
8
8
26
26
9
9
25
25
10
10
24
24
11
11
23
23
12
12
22
22
13
13
21
21
14
14
20
20
19 18 17 1615
19 18 17 1615
July
August
June
May
September
1 2 3
31
4
30
5
29
6
28
7
27
8
26
9
25
10
24
11
23
12
22
13
21
14
20
19 18 17 1615
1 2 3
4
30
5
29
6
28
7
27
8
26
9
25
10
24
11
23
12
22
13
21
14
20
19 18 17 1615
April
2015
October
1 2 3
1 2 3
31
4
4
30
30
5
5
29
29
6
6
28
28
7
7
27
27
8
8
26
26
9
9
25
25
10
10
24
24
11
11
23
23
12
12
22
22
13
13
1 2 3
1 2 3
21
21
14
14
31
4
4
20
20
30
19 18 17 1615
19 18 17 1615
5
5
29
6
6
28
28
7
7
1 2 3
27
27
31
4
8
8
30
5
26
26
9
9
29
6
25
25
10
10
28
7
24
24
11 27
11
8
23
23
12
12
26
9
22
22
13
13
25
21
21
10
14
14
20
20
24
19 18 17 1615
19 18 17 1615
11
23
12
22
13
21
14
20
19 18 17 1615
November
March
February
December
January
538
\sffamily
\colorlet{winter}{blue}
\colorlet{spring}{green!60!black}
\colorlet{summer}{orange}
\colorlet{fall}{red}
% A counter, since TikZ is not clever enough (yet) to handle
% arbitrary angle systems.
\newcount\mycount
\begin{tikzpicture}
[transform shape,
every day/.style={anchor=mid,font=\fontsize{6}{6}\selectfont}]
\node{\normalsize\the\year};
\foreach \month/\monthcolor in
{1/winter,2/winter,3/spring,4/spring,5/spring,6/summer,
7/summer,8/summer,9/fall,10/fall,11/fall,12/winter}
{
% Compute angle:
\mycount=\month
\advance\mycount by -1
\multiply\mycount by 30
\advance\mycount by -90
% The actual calendar
\calendar at (\the\mycount:6.4cm)
[
dates=\the\year-\month-01 to \the\year-\month-last,
]
if (day of month=1) {\color{\monthcolor}\tikzmonthcode}
if (Sunday) [red]
if (all)
{
% Again, compute angle
\mycount=1
\advance\mycount by -\pgfcalendarcurrentday
\multiply\mycount by 11
\advance\mycount by 90
\pgftransformshift{\pgfpointpolar{\mycount}{1.4cm}}
};
}
\end{tikzpicture}
Next, let’s us have a whole year in a tight column:
539
01
02
03
04
05
06
07
08
09
10
11
12
5
12
19
26
2
9
16
23
2
9
16
23
30
6
13
20
27
4
11
18
25
1
8
15
22
29
6
13
20
27
3
10
17
24
31
7
14
21
28
5
12
19
26
2
9
16
23
30
7
14
21
28
6
13
20
27
3
10
17
24
3
10
17
24
31
7
14
21
28
5
12
19
26
2
9
16
23
30
7
14
21
28
4
11
18
25
1
8
15
22
29
6
13
20
27
3
10
17
24
1
8
15
22
29
7
14
21
28
4
11
18
25
4
11
18
25
1
8
15
22
29
6
13
20
27
3
10
17
24
1
8
15
22
29
5
12
19
26
2
9
16
23
30
7
14
21
28
4
11
18
25
2
9
16
23
30
1
8
15
22
29
5
12
19
26
5
12
19
26
2
9
16
23
30
7
14
21
28
4
11
18
25
2
9
16
23
30
6
13
20
27
3
10
17
24
1
8
15
22
29
5
12
19
26
3
10
17
24
31
2
9
16
23
30
6
13
20
27
6
13
20
27
3
10
17
24
1
8
15
22
29
5
12
19
26
3
10
17
24
31
7
14
21
28
4
11
18
25
2
9
16
23
30
6
13
20
27
4
11
18
25
3
10
17
24
31
7
14
21
28
7
14
21
28
4
11
18
25
2
9
16
23
30
6
13
20
27
4
11
18
25
1
8
15
22
29
5
12
19
26
3
10
17
24
31
7
14
21
28
5
12
19
26
4
11
18
25
1
8
15
22
1
8
15
22
29
5
12
19
26
3
10
17
24
31
7
14
21
28
5
12
19
26
2
9
16
23
30
6
13
20
27
4
11
18
25
1
8
15
22
29
6
13
20
27
\begin{tikzpicture}
\small\sffamily
\colorlet{darkgreen}{green!50!black}
\calendar[dates=\year-01-01 to \year-12-31,week list,
month label left,month yshift=0pt,
month text=\textcolor{darkgreen}{\%m0}]
if (Sunday) [black!50];
\end{tikzpicture}
540
46
Chains
Tik Z Library chains
\usetikzlibrary{chains} % LATEX and plain TEX
\usetikzlibrary[chains] % ConTEXt
This library defines options for creating chains.
46.1
Overview
Chains are sequences of nodes that are – typically – arranged in a row or a column and that are – typically –
connected by edges. More generally, they can be used to position nodes of a branching network in a systematic
manner. For the positioning of nodes in rows and columns you can also use matrices, see Section 20, but
chains can also be used to describe the connections between nodes that have already been connected using,
say, matrices. Thus, it often makes sense to use matrices for the positioning of elements and chains to
describe the connections.
46.2
Starting and Continuing a Chain
Typically, you construct one chain at a time, but it is permissible to construct multiple chains simultaneously.
In this case, the chains must be named differently and you must specify for each node which chain it belongs
to.
The first step toward creating a chain is to use the start chain option.
/tikz/start chain=hchain nameihdirectioni
(no default)
This key should, but need not, be given as an option to a scope enclosing all nodes of the chain.
Typically, this will be a scope or the whole tikzpicture, but it might just be a path on which all
nodes of the chain are found. If no hchain namei is given, the default value chain will be used instead.
The key starts a chain named hchain namei and makes it active, which means that it is currently being
constructed. The start chain can be issued only once to activate a chain, inside a scope in which a
chain is active you cannot use this option once more (for the same chain name). The chain stops being
active at the end of the scope in which the start chain command was given.
Although chains are only locally active (that is, active inside the scope the start chain command
was issued), the information concerning the chains is stored globally and it is possible to continue a
chain after a scope has ended. For this, the continue chain option can be used, which allows you to
reactivate an existing chain in another scope.
The hdirectioni is used to determine the placement rule for nodes on the chain. If it is omitted, the
current value of the following key is used:
(no default, initially going right)
/tikz/chain default direction=hdirectioni
This hdirectioni is used in a chain option, if no other hdirectioni is specified.
The hdirectioni can have two different forms: going hoptionsi or placed hoptionsi. The effect of these
rules will be explained in the description of the on chain option. Right now, just remember that the
hdirectioni you provide with the chain option applies to the whole chain.
Other than this, this key has no further effect. In particular, to place nodes on the chain, you must use
the on chain option, described next.
A
B
C
\begin{tikzpicture}[start chain]
% The chain is called just "chain"
\node [on chain] {A};
\node [on chain] {B};
\node [on chain] {C};
\end{tikzpicture}
541
A
B
A
B
C
C
\begin{tikzpicture}
% Same as above, using the scope shorthand
{ [start chain]
\node [on chain] {A};
\node [on chain] {B};
\node [on chain] {C};
}
\end{tikzpicture}
D
\begin{tikzpicture}[start chain=1 going right,
start chain=2 going below,
node distance=5mm,
every node/.style=draw]
\node [on chain=1] {A};
\node [on chain=1] {B};
\node [on chain=1] {C};
0
1
2
\node [on chain=2] at (0.5,-.5) {0};
\node [on chain=2] {1};
\node [on chain=2] {2};
\node [on chain=1] {D};
\end{tikzpicture}
/tikz/continue chain=hchain nameihdirectioni
(no default)
This option allows you to (re)activate an existing chain and to possibly change the default direction. If
the chain name is missing, the name of the innermost activated chain is used. If no chain is activated,
chain is used.
Let us have a look at the two different applications of this option. The first is to change the direction
of a chain as it is being constructed. For this, just give this option somewhere inside the scope of the
chain.
Hello
World
,
this
\begin{tikzpicture}[start chain=going right,node distance=5mm]
\node [draw,on chain] {Hello};
\node [draw,on chain] {World};
\node [draw,continue chain=going below,on chain] {,};
\node [draw,on chain] {this};
\node [draw,on chain] {is};
\end{tikzpicture}
is
The second application is to reactivate a chain after it “has already been closed down.”
A
B
0
1
2
C
D
\begin{tikzpicture}[node distance=5mm,
every node/.style=draw]
{ [start chain=1]
\node [on chain] {A};
\node [on chain] {B};
\node [on chain] {C};
}
{ [start chain=2 going below]
\node [on chain=2] at (0.5,-.5) {0};
\node [on chain=2] {1};
\node [on chain=2] {2};
}
{ [continue chain=1]
\node [on chain] {D};
}
\end{tikzpicture}
46.3
Nodes on a Chain
/tikz/on chain=hchain nameihdirectioni
(no default)
542
This key should be given as an option to a node. When the option is used, the hchain namei must be
the name of a chain that has been started using the start chain option. If hchain namei is the empty
string, the current value of the innermost activated chain is used. If this option is used several times for
a node, only the last invocation “wins.” (To place a node on several chains, use the \chainin command
repeatedly.)
The hdirectioni part is optional. If present, it sets the direction used for this node, otherwise the
hdirectioni that was given to the original start chain option is used (or of the last continue chain
option, which allows you to change this default).
The effects of this option are the following:
1. An internal counter (there is one local counter for each chain) is increased. This counter reflects
the current number of the node in the chain, where the first node is node 1, the second is node 2,
and so on.
The value of this internal counter is globally stored in the macro \tikzchaincount.
2. If the node does not yet have a name, (having been given using the name option or the name-syntax),
the name of the node is set to hchain namei-hvalue of the internal chain counter i. For instance,
if the chain is called nums, the first node would be named nums-1, the second nums-2, and so on.
For the default chain name chain, the first node is named chain-1, the second chain-2, and so
on.
3. Independently of whether the name has been provided automatically or via the name option, the
name of the node is globally stored in the macro \tikzchaincurrent.
4. Except for the first node, the macro \tikzchainprevious is now globally set to the name of the
node of the previous node on the chain. For the first node of the chain, this macro is globally set
to the empty string.
5. Except possibly for the first node of the chain, the placement rule is now executed. The placement
rule is just a Tik Z option that is applied automatically to each node on the chain. Depending
on the form of the hdirectioni parameter (either the locally given one or the one given to the
start chain option), different things happen.
First, it makes a difference whether the hdirectioni starts with going or with placed. The difference
is that in the first case, the placement rule is not applied to the first node of the chain, while in the
second case the placement rule is applied also to this first node. The idea is that a going-direction
indicates that we are “going somewhere relative to the previous node” whereas a placed indicates
that we are “placing nodes according to their number.”
Independently of which form is used, the htexti inside hdirectioni that follows going or placed
(separated by a compulsory space) can have two different effects:
(a) If it contains an equal sign, then this htexti is used as the placement rule, that is, it is simply
executed.
(b) If it does not contain an equal sign, then htexti=of \tikzchainprevious is used as the placement rule.
Note that in the first case, inside the htexti you have access to \tikzchainprevious and
\tikzchaincount for doing your positioning calculations.
4
3
2
5
1
\begin{tikzpicture}[start chain=circle placed {at=(\tikzchaincount*30:1.5)}]
\foreach \i in {1,...,10}
\node [on chain] {\i};
\draw (circle-1) -- (circle-10);
\end{tikzpicture}
6
7
8
9
10
6. The following style is executed:
(style, no value)
/tikz/every on chain
This key is executed for every node on a chain, including the first one.
543
Recall that the standard placement rule has a form like right=of (\tikzchainprevious). This
means that each new node is placed to the right of the previous one, spaced by the current value
of node distance.
Hallo
Welt
\begin{tikzpicture}[start chain,node distance=5mm]
\node [draw,on chain] {};
\node [draw,on chain] {Hallo};
\node [draw,on chain] {Welt};
\end{tikzpicture}
The optional hdirectioni allows us to temporarily change the direction in the middle of a chain:
Hello
World
,
this
is
\begin{tikzpicture}[start chain,node distance=5mm]
\node [draw,on chain] {Hello};
\node [draw,on chain] {World};
\node [draw,on chain=going below] {,};
\node [draw,on chain] {this};
\node [draw,on chain] {is};
\end{tikzpicture}
You can also use more complicated computations in the hdirectioni:
.
World
Hello
1
\begin{tikzpicture}[start chain=going {at=(\tikzchainprevious),shift=(30:1)}]
\draw [help lines] (0,0) grid (3,2);
\node [draw,on chain] {1};
\node [draw,on chain] {Hello};
\node [draw,on chain] {World};
\node [draw,on chain] {.};
\end{tikzpicture}
For each chain, two special “pseudo nodes” are created.
Predefined node hchain name i-begin
This node is the same as the first node on the chain. It is only defined after a first node has been
defined.
Predefined node hchain name i-end
This node is the same as the (currently) last node on the chain. As the chain is extended, this node
changes.
The on chain option can also be used, in conjunction with late options, to add an already existing
node to a chain. The following command, which is only defined inside scopes where a start chain option
is present, simplifies this process.
\chainin(hexisting namei) [hoptionsi]
This command makes it easy to add a node to chain that has already been constructed. This node may
even be part of a another chain.
When you say \chainin (some node);, the node some node must already exist. It will then be made
part of the current chain. This does not mean that the node can be changed (it is already constructed,
after all), but the join option can be used to join some node to the previous last node on the chain
and subsequent nodes will be placed relative to some node.
It is permissible to give the on chain option inside the hoptionsi in order to specify on which chain the
node should be put.
This command is just a shortcut for
\path (hexisting namei) [late options={on chain,every chain in,hoptionsi}]
544
In particular, it is possible to continue to path after a \chainin command, though that does not seem
very useful.
existing
is
this
\begin{tikzpicture}[node distance=5mm,
every node/.style=draw,every join/.style=->]
\draw [help lines] (0,0) grid (3,2);
\node[red] (existing) at (0,2) {existing};
Hello
{ [start chain]
\node [draw,on chain,join] {Hello};
\node [draw,on chain,join] {World};
\chainin (existing) [join];
\node [draw,on chain,join] {this};
\node [draw,on chain,join] {is};
}
\end{tikzpicture}
World
Here is an example where nodes are positioned using a matrix and then connected using a chain
\begin{tikzpicture}[every node/.style=draw]
\matrix [matrix of nodes,column sep=5mm,row sep=5mm]
{
|(a)|
World & |(b) [circle]|
peace \\
|(c)|
be
& |(d) [isosceles triangle]| would \\
|(e) [ellipse]| great & |(f)|
! \\
};
World
peace
be
would
great
!
46.4
{ [start chain,every on chain/.style={join=by ->}]
\chainin (a);
\chainin (b);
\chainin (d);
\chainin (c);
\chainin (e);
\chainin (f);
}
\end{tikzpicture}
Joining Nodes on a Chain
(no default)
/tikz/join=withhwithi byhoptionsi
When this key is given to any node on a chain (except possibly for the first node), an edge command is
added after the node. The with part specifies which node should be used for the start point of the edge;
if the with part is omitted, the \tikzchainprevious is used. This edge command gets the hoptionsi
as parameter and the current node as its target. If there is no previous node and no with is given, no
edge command gets executed.
(style, no value)
/tikz/every join
This style is executed each time this command is used.
Note that it makes sense to call this option several times for a node, in order to connect it to several
nodes. This is especially useful for joining in branches, see the next section.
Hallo
Welt
foo
46.5
\begin{tikzpicture}[start chain,node distance=5mm,
every join/.style={->,red}]
\node [draw,on chain,join] {};
\node [draw,on chain,join] {Hallo};
\node [draw,on chain,join] {Welt};
\node [draw,on chain=going below,
join,join=with chain-1 by {blue,<-}] {foo};
\end{tikzpicture}
Branches
A branch is a chain that (typically only temporarily) extends an existing chain. The idea is the following:
Suppose we are constructing a chain and at some node x there is a fork. In this case, one (or even more)
branches starts at this fork. For each branch a chain is created, but the first node on this chain should be x.
545
For this, it is useful to use \chainin on the node x to make it part of the different branch chains and to
name the branch chains in some way that reflects the name of the main chain.
The start branch option provides a shorthand for doing exactly what was just described.
/tikz/start branch=hbranch nameihdirectioni
(no default)
This key is used in the same manner as the start chain command, however, the effect is slightly
different:
• This option may only be used if some chain is already active and there is a (last) node on this
chain. Let us call this node the hfork nodei.
• The chain is not just called hbranch namei, but hcurrent chaini/hbranch namei. For instance, if
the hfork nodei is part of the chain called trunk and the hbranch namei is set to left, the complete
chain name of the branch is trunk/left. The hbranch namei must be given, there is no default
value.
• The hfork nodei is automatically “chained into” the branch chain as its first node. Thus, for the
first node on the branch that you provide, the join option will cause it to be connected to the fork
node.
\begin{tikzpicture}[every on chain/.style=join,every join/.style=->,
node distance=2mm and 1cm]
{ [start chain=trunk]
\node [on chain] {A};
\node [on chain] {B};
γ
β
α
A
B
C
1
?
2
◦
R
3
{ [start branch=numbers going below]
\node [on chain] {1};
\node [on chain] {2};
\node [on chain] {3};
}
{ [start branch=greek going above]
\node [on chain] {$\alpha$};
\node [on chain] {$\beta$};
\node [on chain] {$\gamma$};
}
\node [on chain,join=with trunk/numbers-end,join=with trunk/greek-end] {C};
{ [start branch=symbols going below]
\node [on chain] {$\star$};
\node [on chain] {$\circ$};
\node [on chain] {$\int$};
}
}
\end{tikzpicture}
/tikz/continue branch=hbranch nameihdirectioni
(no default)
This option works like the continue chain option, only hcurrent chaini/hbranch namei is used as the
chain name, rather than just hbranch namei.
β
α
A
B
1
2
C
\begin{tikzpicture}[every on chain/.style=join,every join/.style=->,
node distance=2mm and 1cm]
{ [start chain=trunk]
\node [on chain] {A};
\node [on chain] {B};
{ [start branch=numbers going below] } % just a declaration,
{ [start branch=greek
going above] } % we will come back later
\node [on chain] {C};
% Now come the branches...
{ [continue branch=numbers]
\node [on chain] {1};
\node [on chain] {2};
}
{ [continue branch=greek]
\node [on chain] {$\alpha$};
\node [on chain] {$\beta$};
}
}
\end{tikzpicture}
546
47
Circuit Libraries
Written and documented by Till Tantau, and Mark Wibrow. Inspired by the work of Massimo Redaelli.
47.1
Introduction
The circuit libraries can be used to draw different kinds of electrical or logical circuits. There is not a single
library for this, but a whole hierarchy of libraries that work in concert. The main design goal was to create
a balance between ease-of-use and ease-of-extending, while creating high-quality graphical representations
of circuits.
47.1.1
A First Example
3V
3Ω
4Ω
3Ω
8V
2Ω
1Ω
R = 4Ω
ι
S1
1Ω
8V
2Ω
3Ω
4Ω
3V
3Ω
\begin{tikzpicture}[circuit ee IEC,x=3cm,y=2cm,semithick,
every info/.style={font=\footnotesize},
small circuit symbols,
set resistor graphic=var resistor IEC graphic,
set diode graphic=var diode IEC graphic,
set make contact graphic= var make contact IEC graphic]
% Let us start with some contacts:
\foreach \contact/\y in {1/1,2/2,3/3.5,4/4.5,5/5.5}
{
\node [contact] (left contact \contact) at (0,\y) {};
\node [contact] (right contact \contact) at (1,\y) {};
}
\draw (right contact 1) -- (right contact 2) -- (right contact 3)
-- (right contact 4) -- (right contact 5);
\draw (left contact 1) to [diode] ++(down:1)
to [voltage source={near start,
direction info={volt=3}},
resistor={near end,ohm=3}] ++(right:1)
to (right contact 1);
\draw (left contact 1) to [resistor={ohm=4}] (right contact 1);
\draw (left contact 1) to [resistor={ohm=3}] (left contact 2);
\draw (left contact 2) to [voltage source={near start,
direction info={<-,volt=8}},
resistor={ohm=2,near end}] (right contact 2);
\draw (left contact 2) to [resistor={near start,ohm=1},
make contact={near end,info’={[red]$S_1$}}]
(left contact 3);
\draw (left contact 3) to [current direction’={near start,info=$\iota$},
resistor={near end,info={$R=4\Omega$}}]
(right contact 3);
\draw (left contact 4) to [voltage source={near start,
direction info={<-,volt=8}},
resistor={ohm=2,near end}] (right contact 4);
\draw (left contact 3) to [resistor={ohm=1}] (left contact 4);
\draw (left contact 4) to [resistor={ohm=3}] (left contact 5);
\draw (left contact 5) to [resistor={ohm=4}] (right contact 5);
\draw (left contact 5) to [diode] ++(up:1)
to [voltage source={near start,
direction info={volt=3}},
resistor={near end,ohm=3}] ++(right:1)
to (right contact 5);
\end{tikzpicture}
An important feature of the circuit library is that the appearance of a circuit can be configured in general
ways and that the labels are placed automatically by default. Here is the graphic once more, generated
from exactly the same source code, with only the options of the {tikzpicture} environment replaced by
[rotate=-90,circuit ee IEC,x=3.25cm,y=2.25cm]:
547
3Ω
1Ω
1Ω
3Ω
S1
3V
8V
ι
4Ω
3Ω
47.1.2
3V
8V
4Ω
2Ω
R = 4Ω
2Ω
3Ω
Symbols
A circuit typically consists of numerous electronic elements like logical gates or resistors or diodes that are
connected by wires. In pgf/Tik Z, we use nodes for the electronic elements and normal lines for the wires.
Tik Z offers a large number of different ways of positioning and connecting nodes in general, all of which can
be used here. Additionally, the circuits library defines an additional useful to-path that is particularly
useful for elements like a resistor on a line.
There are many different names that are used to refer to electrical “elements,” so a bit of terminology
standardization is useful: We will call such elements symbols. A symbol shape is a pgf shape declared using
the \pgfdeclareshape command. A symbol node is a node whose shape is a symbol shape.
47.1.3
Symbol Graphics
Symbols can be created by \node[shape=some symbol shape]. However, in order to represent some symbols
correctly, just using standard pgf shapes is not sufficient. For instance, most symbols have a visually
appealing “default size,” but the size of a symbol shape depends only on the current values of parameters
like minimum height or inner xsep.
For these reasons, the circuit libraries introduce the concept of a symbol graphic. This is a style that
causes a \node to not only have the correct shape, but also the correct size and the correct path usage. More
generally, this style may set up things in any way so that the “symbol looks correct”. When you write, for
instance, \node[diode], then the style called diode graphic is used, which in turn is set to something like
shape=diode IEC,draw,minimum height=....
Here is an overview of the different kinds of circuit libraries:
• The Tik Z-library circuits defines general keys for creating circuits. Mostly, these keys are useful for
defining more specialized libraries.
You normally do not use this library directly since it does not define any symbol graphics.
• The Tik Z-library circuits.logic defines keys for creating logical gates like and-gates or xor-gates.
However, this library also does not actually define any symbol graphics; this is done by two sublibraries:
– The library circuits.logic.US defines symbol graphics that cause the logical gates to be rendered in the “US-style.” It includes all of the above libraries and you can use this library directly.
– The library circuits.logic.IEC also defines symbol graphics for logical gates, but it uses rectangular gates rather that the round US-gates. This library can coexist peacefully with the above
library, you can change which symbol graphics are used “on the fly.”
• The Tik Z-library cirucits.ee defines keys for symbols from electrical engineering like resistors or
capacitors. Again, sublibraries define the actual symbol graphics.
– The library circuits.ee.IEC defines symbol shapes that follow the IEC norm.
• The pgf-libraries shapes.gates.* define (circuit) symbol shapes. However, you normally do not use
these shapes directly, rather you use a style that uses an appropriate symbol graphic, which in turn
uses one of these shapes.
Let us have a look at a simple example. Suppose we wish to create a logical circuit. Then we first have
to decide which symbol graphics we would like to use. Suppose we wish to use the US-style, then we would
include the library circuits.logic.US. If you wish to use IEC-style symbols, use circuits.logic.IEC. If
you cannot decide, include both:
548
\usetikzlibrary{circuits.logic.US,circuits.logic.IEC}
To create a picture that contains a US-style circuit you can now use the option circuit logic US. This
will set up keys like and gate to create use an appropriate symbol graphic for rendering an and gate. Using
the circuit logic IEC instead will set up and gate to use another symbol graphic.
\begin{tikzpicture}[circuit logic US]
\matrix[column sep=7mm]
{
\node (i0) {0}; &
& \\
& \node [and gate] (a1) {}; & \\
\node (i1) {0}; &
& \node [or gate] (o) {};\\
& \node [nand gate] (a2) {}; & \\
\node (i2) {1}; &
& \\
};
\draw (i0.east) -- ++(right:3mm) |- (a1.input 1);
\draw (i1.east) -- ++(right:3mm) |- (a1.input 2);
\draw (i1.east) -- ++(right:3mm) |- (a2.input 1);
\draw (i2.east) -- ++(right:3mm) |- (a2.input 2);
\draw (a1.output) -- ++(right:3mm) |- (o.input 1);
\draw (a2.output) -- ++(right:3mm) |- (o.input 2);
\draw (o.output) -- ++(right:3mm);
\end{tikzpicture}
0
0
1
0
&
≥1
0
&
1
47.1.4
\begin{tikzpicture}[circuit logic IEC]
\matrix[column sep=7mm]
{
\node (i0) {0}; &
& \\
& \node [and gate] (a1) {}; & \\
\node (i1) {0}; &
& \node [or gate] (o) {};\\
& \node [nand gate] (a2) {}; & \\
\node (i2) {1}; &
& \\
};
\draw (i0.east) -- ++(right:3mm) |- (a1.input 1);
\draw (i1.east) -- ++(right:3mm) |- (a1.input 2);
\draw (i1.east) -- ++(right:3mm) |- (a2.input 1);
\draw (i2.east) -- ++(right:3mm) |- (a2.input 2);
\draw (a1.output) -- ++(right:3mm) |- (o.input 1);
\draw (a2.output) -- ++(right:3mm) |- (o.input 2);
\draw (o.output) -- ++(right:3mm);
\end{tikzpicture}
Annotations
An annotation is a little extra drawing that can be added to a symbol. For instance, when you add two
little parallel arrows pointing away from some electrical element, this usually means that the element is light
emitting.
Instead of having one symbol for “diode” and another for “light emitting diode,” there is just one diode
symbol, but you can add the light emitting annotation to it. This is done by passing the annotation as
a parameter to the symbol as in the following example:
\tikz [circuit ee IEC]
\draw (0,0) to [diode={light emitting}] (3,0)
to [resistor={adjustable}] (3,2);
47.2
The Base Circuit Library
Tik Z Library circuits
\usetikzlibrary{circuits} % LATEX and plain TEX
\usetikzlibrary[circuits] % ConTEXt
This library is a base library that is included by other circuit libraries. You do not include it directly,
but you will typically use some of the general keys, described below.
549
(no value)
/tikz/circuits
This key should be passed as an option to a picture or a scope that contains a circuit. It will do some
internal setups. This key is normally called by more specialized keys like circuit ee IEC.
47.2.1
Symbol Size
(no default, initially 7pt)
/tikz/circuit symbol unit=hdimensioni
This dimension is a “unit” for the size of symbols. The libraries generally define the sizes of symbols
relative to this dimension. For instance, the longer side of an inductor is, by default, in the IEC library
equal to five times this hdimensioni. When you change this hdimensioni, the size of all symbols will
automatically change accordingly.
Note, that it is still possible to overwrite the size of any particular symbol. These settings apply only
to the default sizes.
\begin{tikzpicture}[circuit ee IEC]
\draw (0,1) to [resistor] (3.5,1);
\draw[circuit symbol unit=14pt]
(0,0) to [resistor] (3.5,0);
\end{tikzpicture}
(style, no value)
/tikz/huge circuit symbols
This style sets the default circuit symbol unit to 10pt.
(style, no value)
/tikz/large circuit symbols
This style sets the default circuit symbol unit to 8pt.
(style, no value)
/tikz/medium circuit symbols
This style sets the default circuit symbol unit to 7pt.
(style, no value)
/tikz/small circuit symbols
This style sets the default circuit symbol unit to 6pt.
(style, no value)
/tikz/tiny circuit symbols
This style sets the default circuit symbol unit to 5pt.
/tikz/circuit symbol size=width hwidthi height hheighti
(no default)
This key sets minimum height to hheighti times the current value of the circuit symbol unit and the
minimum width to hwidthi times this value. Thus, this option can be used with a node command to set
the size of the node as a multiple of the circuit symbol unit.
\begin{tikzpicture}[circuit ee IEC]
\draw (0,1) to [resistor] (2,1) to[inductor] (4,1);
\begin{scope}
[every resistor/.style={circuit symbol size=width 3 height 1}]
\draw (0,0) to [resistor] (2,0) to[inductor] (4,0);
\end{scope}
\end{tikzpicture}
47.2.2
Declaring New Symbols
(no default)
/tikz/circuit declare symbol=hnamei
This key is used to declare a symbol. It does not cause this symbol to be shown nor does it set a graphic
to be used for the symbol, it simply “prepares” several keys that can later be used to draw a symbol
and to configure it.
In detail, the first key that is defined is just called hnamei. This key should be given as an option to
a node or on a to path, as explained below. The key will take options, which can be used to influence
the way the symbol graphic is rendered.
Let us have a look at an example. Suppose we want to define a symbol called foo, which just looks like
a simple rectangle. We could then say
550
\tikzset{circuit declare symbol=foo}
The symbol could now be used like this:
\node [foo]
at (1,1) {};
\node [foo={red}] at (2,1) {};
However, in the above example we would not actually see anything since we have not yet set up the
graphic to be used by foo. For this, we must use a key called set foo graphic or, generally, set
hnamei graphic. This key gets graphic options as parameter that will be set when a symbol foo should
be shown:
\begin{tikzpicture}
[circuit declare symbol=foo,
set foo graphic={draw,shape=rectangle,minimum size=5mm}]
\node [foo]
at (1,1) {};
\node [foo={red}] at (2,1) {};
\end{tikzpicture}
In detail, when you use the key hnamei=hoptionsi with a node, the following happens:
1. The inner sep is set to 0.5pt.
2. The following style is executed:
(style, no value)
/tikz/every circuit symbol
Use this style to set up things in general.
3. The graphic options that have been set using set hnamei graphic are set.
4. The style every hnamei is executed. You can use it to configure the symbol further.
5. The hoptionsi are executed.
The key hnamei will have a different effect when it is used on a to path command inside a circuit
environment (the circuit environment sets up to paths in such a way that the use of a key declared
using circuit declare symbol is automatically detected). When hnamei is used on a to path, the
above actions also happen (setting the inner separation, using the symbol graphic, and so on), but they
are passed to the key circuit handle symbol, which is explained next.
(no default)
/tikz/circuit handle symbol=hoptionsi
This key is mostly used internally. Its purpose is to render a symbol. The effect of this key differs,
depending on whether it is used as the optional argument of a to path command or elsewhere.
If the key is not used as an argument of a to path command, the hoptionsi are simply executed.
The more interesting case happens when the key is given on a to path command. In this case, several
things happen:
1. The to path is locally changed and set to an internal path (which you should not try to change)
that consists mostly of a single straight line.
2. The hoptionsi are tentatively executed with filtering switched on. Everything is filtered out, except
for the key pos and also the styles at start, very near start, near start, midway, near end,
very near end, and at end. If none of them is found, midway is used.
3. The filtered option is used to determine a position for the symbol on the path. At the given position
(with pos=0 representing the start and pos=1 representing the end), a node will be added to the
path (in a manner to be described presently).
4. This node gets hoptionsi as its option list.
5. The node is added by virtue of a special markings decoration. This means that a mark command
is executed that causes the node to be placed as a mark on the path.
6. The marking decoration will automatically subdivide the path and cause a line to be drawn from
the start of the path to the node’s border (at the position that lies on a line from the node’s center
to the start of the path) and then from the node’s border (at a position on the other side of the
node) to the end of the path.
551
7. The marking decoration will also take care of the case that multiple marks are present on a path,
in this case the lines from and to the borders of the nodes are only between consecutive nodes.
8. The marking decoration will also rotate the coordinate system in such a way that the x-axis points
along the path. Thus, if you use the transform shape option, the node will “point along” the
path.
9. In case a node is at pos=0 or at pos=1 some special code will suppress the superfluous lines to the
start or end of the path.
The net effect of all of the above is that a node will be placed “on the path” and the path will have a
“gap” just large enough to encompass the node. Another effect is that you can use this key multiple
times on a path to add several node to a path, provided they do not overlap.
\begin{tikzpicture}[circuit]
\draw (0,0) to [circuit handle symbol={draw,shape=rectangle,near start},
circuit handle symbol={draw,shape=circle,near end}] (3,2);
\end{tikzpicture}
\begin{tikzpicture}[transform shape,circuit]
\draw (0,0) to [circuit handle symbol={draw,shape=rectangle,at start},
circuit handle symbol={draw,shape=circle,near end}] (3,2);
\end{tikzpicture}
47.2.3
Pointing Symbols in the Right Direction
Unlike normal nodes, which generally should not be rotated since this will make their text hard to read,
symbols often need to be rotated. There are two ways of achieving such rotations:
1. When you place a symbol on a to path, the graphic symbol is automatically rotated such that it “points
along the path.” Here is an examples that shows how the inductor shape (which looks, unrotated, like
this:
) is automatically rotated around:
\tikz [circuit ee IEC]
\draw (3,0) to[inductor] (1,0) to[inductor] (0,2);
2. Many shapes cannot be placed “on” a path in this way, namely whenever there are more than two
possible inputs. Also, you may wish to place the nodes first, possibly using a matrix, and connect
them afterwards. In this case, you can simply add rotations like rotate=90 to the shapes to rotate
them. The following four keys make this slightly more convenient:
(no value)
/tikz/point up
This is the same as rotate=90.
\tikz [circuit ee IEC] \node [diode,point up] {};
(no value)
/tikz/point down
This is the same as rotate=-90.
\tikz [circuit ee IEC] \node [diode,point down] {};
552
(no value)
/tikz/point left
This is the same as rotate=-180.
\tikz [circuit ee IEC] \node [diode,point left] {};
(no value)
/tikz/point right
This key has no effect.
\tikz [circuit ee IEC] \node [diode,point right] {};
47.2.4
Info Labels
Info labels are used to add text to a circuit symbol. Unlike normal nodes like a rectangle, circuit symbols
typically do not have text “on” them, but the text is placed next to them (like the text “3 Ω” next to a
resistor).
Tik Z already provides the label option for this purpose. The info option is built on top of this option,
but it comes in some predefined variants that are especially useful in conjunction with circuits.
(no default)
/tikz/info=[hoptionsi]hanglei:htexti
This key has nearly the same effect as the label key, only the following style is used additionally
automatically:
(style, no value)
/tikz/every info
Set this style to configure the styling of info labels. Since this key is not used with normal labels,
it provides an easy way of changing the way info labels look without changing other labels.
The hoptionsi and hanglei are passed directly to the label command.
3Ω
\begin{tikzpicture}[circuit ee IEC,every info/.style=red]
\node [resistor,info=$3\Omega$] {};
\end{tikzpicture}
You will find a detailed discussion of the label option on page 239.
Hint: To place some text on the main node, use center as the hanglei:
R1
3Ω
\begin{tikzpicture}[circuit ee IEC,every info/.style=red]
\node [resistor,info=center:$3\Omega$] {};
\node [resistor,point up,info=center:$R_1$] at (2,0) {};
\end{tikzpicture}
(no default)
/tikz/info’=[hoptionsi]hanglei:htexti
This key works exactly like the info key, only in case the hanglei is missing, it defaults to below instead
of the current value of label position, which is usually above. This means that when you use info,
you get a label above the node, while when you use the info’ key you get a label below the node. In
case the node has been rotated, the positions of the info nodes are rotated accordingly.
4Ω
R2
\begin{tikzpicture}[circuit ee IEC,every info/.style=red]
\draw (0,0) to[resistor={info={$3\Omega$},info’={$R_1$}}] (3,0)
to[resistor={info={$4\Omega$},info’={$R_2$}}] (3,2);
\end{tikzpicture}
3Ω
R1
(no default)
/tikz/info sloped=[hoptionsi]hanglei:htexti
This key works like info, only the transform shape option is set when the label is drawn, causing it
to follow the sloping of the main node.
553
4Ω
\begin{tikzpicture}[circuit ee IEC,every info/.style=red]
\draw (0,0) to[resistor={info sloped={$3\Omega$}}] (3,0)
to[resistor={info sloped={$4\Omega$}}] (3,2);
\end{tikzpicture}
3Ω
(no default)
/tikz/info’ sloped=
4Ω
This is a combination of info’ and info sloped.
\begin{tikzpicture}[circuit ee IEC,every info/.style=red]
\draw (0,0) to[resistor={info’ sloped={$3\Omega$}}] (3,0)
to[resistor={info’ sloped={$4\Omega$}}] (3,2);
\end{tikzpicture}
3Ω
(no default)
/tikz/circuit declare unit={hnamei}{huniti}
This key is used to declare keys that make it easy to attach physical units to nodes. The idea is that
instead of info=$3\Omega$ you can write ohm=3 or instead of info’=$5\mathrm{S}$ you can write
siemens’=5.
In detail, four keys are defined, namely /tikz/hnamei, /tikz/hnamei’, /tikz/hnamei sloped, and
/tikz/hnamei’ sloped. The arguments of all of these keys are of the form [hoptionsi]hanglei:hvaluei
and it is passed (slightly modified) to the corresponding key info, info’, info sloped, or info’ sloped.
The “slight modification” is the following: The text that is passed to the, say, info key is not hvaluei,
but rather $\mathrm{hvalueihuniti}$
This means that after you said circuit declare unit={ohm}{\Omega}, then ohm=5k will have the
same effect as info={[every ohm]$\mathrm{5k\Omega}$}. Here, every ohm is a style that allows
you to configure the appearance of this unit. Since the info key is used internally, by changing the
every info style, you can change the appearance of all units infos.
\begin{tikzpicture}[circuit ee IEC,circuit declare unit={my ohm}{O}]
\draw (0,0) to[resistor={my ohm’ sloped=3}] (3,2);
\end{tikzpicture}
3O
47.2.5
Declaring and Using Annotations
Annotations are quite similar to info labels. The main difference is that they generally cause something to
be drawn by default rather than some text to be added (although an annotation might also add some text).
Annotations can be declared using the following key:
/tikz/circuit declare annotation={hnamei}{hdistancei}{hpathi}
(no default)
This key is used to declare an annotation named hnamei. Once declared, it can be used as an argument
of a symbol and will add the drawing in hpathi to the symbol. In detail, the following happens:
The Main Keys. Two keys called hnamei and hnamei’ are defined. The second causes the annotation
to be “mirrored and placed on the other side” of the symbol. Both of these keys may also take further
keys as parameter like info keys. Whenever the hnamei key is used, a local scope is opened and in this
scope the following things are done:
1. The style every hnamei is executed.
2. The following style is executed and then arrows=->:
(style, no value)
/tikz/annotation arrow
This style should set the > key to some desirable arrow tip.
554
3. The coordinate system is shifted such that the origin is at the north anchor of the symbol. (For
the hnamei’ key the coordinate system is flipped and shifted such that the origin is at the south
anchor of the symbol.)
4. The label distance is locally set to hdistancei.
5. The parameter options given to the hnamei key are executed.
6. The hpathi is executed.
Usage. What all of the above amounts to is best explained by an example. Suppose we wish to create
an annotation that looks like a little circular arrow (like ). We could then say:
\tikzset{circuit declare annotation=
{circular annotation}
{9pt}
{(0pt,8pt) arc (-270:80:3.5pt)}
}
We can then use it like this:
\tikz[circuit ee IEC]
\draw (0,0) to [resistor={circular annotation}]
(3,0);
Well, not very impressive since we do not see anything. This is due to the fact that the hpathi becomes
part of a path that contains the symbol node an nothing else. This path is not drawn or filled, so we
do not see anything. What we must do is to use an edge path operation:
\tikzset{circuit declare annotation={circular annotation}{9pt}
{(0pt,8pt) edge[to path={arc(-270:80:3.5pt)}] ()}
}
\tikz[circuit ee IEC]
\draw (0,0) to [resistor={circular annotation}]
(3,0)
to [capacitor={circular annotation’}] (3,2);
The hdistancei is important for the correct placement of additional info labels. When an annotation
is present, the info labels may need to be moved further away from the symbol, but not always. For
this reason, an annotation defines an additional hdistancei that is applied to all info labels given as
parameters to the annotation. Here is an example, that shows the difference:
5Ω
5Ω
47.2.6
\tikz[circuit ee IEC]
\draw (0,0) to [resistor={circular annotation,ohm=5}]
(2,0)
to [resistor={circular annotation={ohm=5}}] (4,0);
Theming Symbols
For each symbol, a certain graphical representation is chosen to actually show the symbol. You can modify
this graphical representation in several ways:
• You can select a different library and use a different circuit ... key. This will change all graphics
used for the symbols.
• You can generally change the size of graphic symbols by setting circuit size unit to a different
value or using a key like small circuit symbols.
• You can add options to the graphics used by symbols either globally by setting the every circuit
symbol style or locally by setting the every hnamei style, where hnamei is the name of a symbol. For
instance, in the following picture the symbols are ridiculously thick and resistors are red.
\begin{tikzpicture}
[circuit ee IEC,
every circuit symbol/.style={ultra thick},
every resistor/.style={red}]
\draw (0,0) to [inductor] ++(right:3) to [resistor] ++(up:2);
\end{tikzpicture}
555
• You can selectively change the graphic used for a symbol by saying set resistor graphic=.
• You can change one or more of the following styles:
(style, initially draw)
/tikz/circuit symbol open
This style is used with symbols that consist of lines that surround some area. For instance, the
IEC version of a resistor is an open symbol.
\tikz [circuit ee IEC,
circuit symbol open/.style={thick,draw,fill=yellow}]
\draw (0,0) to [inductor] ++(right:3) to [resistor] ++(up:2);
/tikz/circuit symbol filled
(style, initially draw,fill=black)
This style is used with symbols that are completely filled. For instance, the variant IEC version
of an inductor is a filled, black rectangle.
(style, initially draw)
/tikz/circuit symbol lines
This style is used with symbols that consist only of lines that do not surround anything. Examples
are a capacitor.
\tikz [circuit ee IEC,
circuit symbol lines/.style={thick,draw=red}]
\draw (0,0) to [capacitor] ++(right:3) to [resistor] ++(up:2);
(style, initially draw)
/tikz/circuit symbol wires
This style is used for symbols that consist only of “wires.” The difference to the previous style
is that a symbol consisting of wires will look strange when the lines are thicker than the lines of
normal wires, while for symbols consisting of lines (but not wires) it may look nice to make them
thicker. An example is the make contact symbol.
Compare
\tikz [circuit ee IEC,circuit symbol lines/.style={draw,very thick}]
\draw (0,0) to [capacitor={near start},
make contact={near end}] (3,0);
to
\tikz [circuit ee IEC,circuit symbol wires/.style={draw,very thick}]
\draw (0,0) to [capacitor={near start},
make contact={near end}] (3,0);
All circuit environments like circuit logic IEC mainly use options like set and gate graphic=...
to set up the graphics used for a certain symbol. It turns out that graphic hidden in the “...” part
is also always available as a separate style, whose name contains the library’s initials. For instance, the
circuit logic IEC option actually contains the following command:
set and gate graphic = and gate IEC graphic,
The and gate IEC graphic style, in turn, is defined as follows:
\tikzset{and gate IEC graphic/.style=
{
circuit symbol open,
circuit symbol size=width 2.5 height 4,
shape=and gate IEC,
inner sep=.5ex
}
}
556
Normally, you do not need to worry about this, since you will not need to access a style like and gate
IEC graphic directly; you will only use the and gate key. However, sometimes libraries define variants of a
graphic; for instance, there are two variants for the resistor graphic in the IEC library. In this case you can
set the graphic for the resistor to this variant (or back to the original) by saying set resistor graphic
yourself:
\begin{tikzpicture}[circuit ee IEC]
% Standard resistor
\draw (0,2) to [resistor] (3,2);
% Var resistor
\begin{scope}[set resistor graphic=var resistor IEC graphic]
\draw (0,1) to [resistor] (3,1);
% Back to original
\draw [set resistor graphic=resistor IEC graphic]
(0,0) to [resistor] (3,0);
\end{scope}
\end{tikzpicture}
47.3
47.3.1
Logical Circuits
Overview
A logical circuit is a circuit that contains what we call logical gates like an and gate or an xor gate. The
logical libraries are intended to make it easy to draw such circuits.
In the following, we first have a look at the different libraries that can be used in principle and how the
symbols look like. Then we have a more detailed look at how the symbols are used. Finally, we discuss the
implementation details.
There are different ways of depicting logical gates, which is why there are different (sub-)libraries for
drawing them. They provide the necessary graphical representations of the symbols declared in the following
library:
Tik Z Library circuits.logic
\usetikzlibrary{circuits.logic} % LATEX and plain TEX
\usetikzlibrary[circuits.logic] % ConTEXt
This library declares the logical gate symbols, but does not provide the symbol graphics. The library
also defines the following key which, however, is also only used indirectly, namely by other libraries:
(no value)
/tikz/circuit logic
This style calls the keys circuit (which internally calls every circuit, then it defines the inputs
key and it calls the every circuit logic key.
(no default)
/tikz/inputs=hinputsi
This key is defined only inside the scope of a circuit logic. There, it has the same effect as
logic gate inputs, described on page 560.
(style, no value)
/tikz/every circuit logic
Use this key to configure the appearance of logical circuits.
Since the circuit.logic library does not define any actual graphics, you need to use one of the following
libraries, instead:
Tik Z Library circuits.logic.IEC
\usepgflibrary{circuits.logic.IEC}
\usepgflibrary[circuits.logic.IEC]
\usetikzlibrary{circuits.logic.IEC}
\usetikzlibrary[circuits.logic.IEC]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library provides graphics based on gates recommended by the International Electrotechnical Commission. When you include this library, you can use the following key to set up a scope that contains a
logical circuit where the gates are shown in this style.
557
(no value)
/tikz/circuit logic IEC
This key calls circuit logic and installs the IEC-like graphics for the logical symbols like
and gate.
As explained in Section 47.2.6, for each graphic symbol of the library there is also a style that stores
this particular appearance. These keys are called and gate IEC graphic, or gate IEC graphic,
and so on.
0
&
≥1
0
&
1
\begin{tikzpicture}[circuit logic IEC,
every circuit symbol/.style={
logic gate IEC symbol color=black,
fill=blue!20,draw=blue,very thick}]
\matrix[column sep=7mm]
{
\node (i0) {0}; &
& \\
& \node [and gate] (a1) {}; & \\
\node (i1) {0}; &
& \node [or gate] (o) {};\\
& \node [nand gate] (a2) {}; & \\
\node (i2) {1}; &
& \\
};
\draw (i0.east) -- ++(right:3mm) |- (a1.input 1);
\draw (i1.east) -- ++(right:3mm) |- (a1.input 2);
\draw (i1.east) -- ++(right:3mm) |- (a2.input 1);
\draw (i2.east) -- ++(right:3mm) |- (a2.input 2);
\draw (a1.output) -- ++(right:3mm) |- (o.input 1);
\draw (a2.output) -- ++(right:3mm) |- (o.input 2);
\draw (o.output) -- ++(right:3mm);
\end{tikzpicture}
Tik Z Library circuits.logic.US
\usepgflibrary{circuits.logic.US}
\usepgflibrary[circuits.logic.US]
\usetikzlibrary{circuits.logic.US}
\usetikzlibrary[circuits.logic.US]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library provides graphics showing “American” logic gates. It defines the following key:
(no value)
/tikz/circuit logic US
This style calls circuit logic and installs US-like graphics for the logical symbols like and gate.
For instance, it says
set and gate graphic = and gate US graphic
Here is an example:
0
0
1
\begin{tikzpicture}[circuit logic CDH,
tiny circuit symbols,
every circuit symbol/.style={
fill=white,draw}]
\matrix[column sep=7mm]
{
\node (i0) {0}; &
& \\
& \node [and gate] (a1) {}; & \\
\node (i1) {0}; &
& \node [or gate] (o) {};\\
& \node [nand gate] (a2) {}; & \\
\node (i2) {1}; &
& \\
};
\draw (i0.east) -- ++(right:3mm) |- (a1.input 1);
\draw (i1.east) -- ++(right:3mm) |- (a1.input 2);
\draw (i1.east) -- ++(right:3mm) |- (a2.input 1);
\draw (i2.east) -- ++(right:3mm) |- (a2.input 2);
\draw (a1.output) -- ++(right:3mm) |- (o.input 1);
\draw (a2.output) -- ++(right:3mm) |- (o.input 2);
\draw (o.output) -- ++(right:3mm);
\end{tikzpicture}
558
Tik Z Library circuits.logic.CDH
\usepgflibrary{circuits.logic.CDH}
\usepgflibrary[circuits.logic.CDH]
\usetikzlibrary{circuits.logic.CDH}
\usetikzlibrary[circuits.logic.CDH]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library provides graphics based on the logic symbols used in A. Croft, R. Davidson, and M.
Hargreaves (1992), Engineering Mathematics, Addison-Wesley, 82–95. They are identical to the US-style
symbols, except for the and- and nand-gates.
(no value)
/tikz/circuit logic CDH
This key calls circuit logic US and installs the two special and- and nand-gates, that is, it uses
set and gate graphic with and gate CDH graphic and likewise for nand-gates.
Inside circuit logic XYZ scopes, you can now use the keys shown in Section 47.3.2. We have a more
detailed look at one of them, all the other work the same way:
(no value)
/tikz/and gate
This key should be passed to a node command. It will cause the node to “look like” an and gate,
where the exact appearance of the gate is dictated by the which circuit environment is used. To further
configure the appearance of the and gate, see Section 47.2.6.
&
\tikz [circuit logic IEC] \node [and gate] {$A$};
A
A
A
\tikz [circuit logic US]
{
\node [and gate,point down] {$A$};
\node [and gate,point down,info=center:$A$] at (1,0) {};
}
Inputs. Multiple inputs can be specified for a logic gate (provided they support multiple inputs: a not
gate—also known as an inverter—does not). However, there is an upper limit for the number of inputs
which has been set to 1024, which should be way more than would ever be needed.
The following key is used to configure the inputs. It is available only inside a circuit logic environment.
/tikz/inputs=hinput listi
(no default, initially {normal,normal})
If a gate has n inputs, the hinput listi should consists of n letters, each being i for “inverted” or
n for “normal.” Inverted gates will be indicated by a little circle. In any case the anchors for the
inputs will be set up appropriately, numbered from top to bottom input 1, input 2, . . . and so on.
If the gate only supports one input the anchor is simply called input with no numerical index.
&
\begin{tikzpicture}[circuit logic IEC]
\node[and gate,inputs={inini}] (A) {};
\foreach \a in {1,...,5}
\draw (A.input \a -| -1,0) -- (A.input \a);
\draw (A.output) -- ++(right:5mm);
\end{tikzpicture}
(This key is just a shorthand for logic gate inputs, described in detail on page 560. There you will
also find descriptions of how to configure the size of the inverted circles and the way the symbol size
increases when there are too many inputs.)
Output. Every logic gate has one anchor called output.
47.3.2
Symbols: The Gates
The following table shows which symbols are declared by the main circuits.logic library and their appearance in the different sublibraries.
559
Key
Appearance inside
circuit logic IEC
/tikz/and gate
/tikz/nand gate
Appearance inside
circuit logic CDH
&
&
≥1
/tikz/or gate
/tikz/nor gate
/tikz/xor gate
/tikz/xnor gate
/tikz/not gate
/tikz/buffer gate
47.3.3
Appearance inside
circuit logic US
≥1
=1
=1
1
1
Implementation: The Logic Gates Shape Library
The previous sections described the Tik Z interface for creating logical circuits. In this section we take a
closer look at the underlying pgf libraries.
Just as there are several Tik Z circuit libraries, there are two underlying pgf shape libraries, one for
creating US-style gates and one for IEC-style gates. These libraries define shapes only. It is the job of the
circuit libraries to “theme” them so that they “look nice.” However, in principle, you can also use these
shapes directly.
Let us begin with the base library that defines the handling of inputs.
Tik Z Library shapes.gates.logic
\usepgflibrary{shapes.gates.logic}
\usepgflibrary[shapes.gates.logic]
\usetikzlibrary{shapes.gates.logic}
\usetikzlibrary[shapes.gates.logic]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library defines common keys used by all logical gate shapes.
/pgf/logic gate inputs=hinput listi
(no default, initially {normal,normal})
Specify the inputs for the logic gate. The keyword inverted indicates an inverted input which will
mean pgf will draw a circle attached to the main shape of the logic gate. Any keyword that is
not inverted will be treated as a “normal” or “non-inverted” input (however, for readability, you
may wish to use normal or non-inverted), and pgf will not draw the circle. In both cases the
anchors for the inputs will be set up appropriately, numbered from top to bottom input 1, input
2, . . . and so on. If the gate only supports one input the anchor is simply called input with no
numerical index.
&
\begin{tikzpicture}[minimum height=0.75cm]
\node[and gate IEC, draw, logic gate inputs={inverted, normal, inverted}]
(A) {};
\foreach \a in {1,...,3}
\draw (A.input \a -| -1,0) -- (A.input \a);
\draw (A.output) -- ([xshift=0.5cm]A.output);
\end{tikzpicture}
560
For multiple inputs it may be somewhat unwieldy to specify a long list, thus, the following “shorthand” is permitted (this is an extension of ideas due to Juergen Werber and Christoph Bartoschek):
Using i for inverted and n for normal inputs, hinput listi can be specified without the commas. So,
for example, ini is equivalent to inverted, normal, inverted.
\begin{tikzpicture}[minimum height=0.75cm]
\node[or gate US, draw,logic gate inputs=inini] (A) {};
\foreach \a in {1,...,5}
\draw (A.input \a -| -1,0) -- (A.input \a);
\draw (A.output) -- ([xshift=0.5cm]A.output);
\end{tikzpicture}
The height of the gate may be increased to accommodate the number of inputs. In fact, it depends on
three variables: n, the number of inputs, r, the radius of the circle used to indicate an inverted input
and s, the distance between the centers of the inputs. The default height is then calculated according
to the expression (n + 1) × max(2r, s). This then may be increased to accommodate the node contents
or any minimum size specifications.
The radius of the inverted input circle and the distance between the centers of the inputs can be
customized using the following keys:
(no default, initially 2pt)
/pgf/logic gate inverted radius=hlengthi
Set the radius of the circle that is used to indicate inverted inputs. This is also the radius of the
circle used for the inverted output of the nand, nor, xnor and not gates.
\begin{tikzpicture}[minimum height=0.75cm]
\tikzset{every node/.style={shape=nand gate CDH, draw, logic gate inputs=ii}}
\node[logic gate inverted radius=2pt] {A};
\node[logic gate inverted radius=4pt] at (0,-1) {B};
\end{tikzpicture}
A
B
/pgf/logic gate input sep=hlengthi
(no default, initially .125cm)
Set the distance between the centers of the inputs to the logic gate.
&
&
A
B
\begin{tikzpicture}[minimum size=0.75cm]
\draw [help lines] grid (3,2);
\tikzset{every node/.style={shape=and gate IEC, draw, logic gate inputs=ini}}
\node[logic gate input sep=0.33333cm] at (1,1)(A) {A};
\node[logic gate input sep=0.5cm]
at (3,1) (B) {B};
\foreach \a in {1,...,3}
\draw (A.input \a -| 0,0) -- (A.input \a)
(B.input \a -| 2,0) -- (B.input \a);
\end{tikzpicture}
pgf will increase the size of the logic gate to accommodate the number of inputs, and the size of the
inverted radius and the separation between the inputs. However with all shapes in this library, any
increase in size (including any minimum size requirements) will be applied so that the default aspect
ratio is unaltered. This means that changing the height will change the width and vice versa.
47.3.4
Implementation: The US-Style Logic Gates Shape Library
Tik Z Library shapes.gates.logic.US
\usepgflibrary{shapes.gates.logic.US}
\usepgflibrary[shapes.gates.logic.US]
\usetikzlibrary{shapes.gates.logic.US}
\usetikzlibrary[shapes.gates.logic.US]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library provides “American” logic gate shapes whose names are suffixed with the identifier US.
Additionally, alternative and and nand gates are provided which are based on the logic symbols used in
A. Croft, R. Davidson, and M. Hargreaves (1992), Engineering Mathematics, Addison-Wesley, 82–95.
These two shapes are suffixed with CDH.
561
The “compass point” anchors apply to the main part of the shape and do not include any inverted
inputs or outputs. This library provides an additional feature to facilitate the relative positioning of
logic gates:
(no default, initially false)
/pgf/logic gate anchors use bounding box=hbooleani
When set to true this key will ensure that the compass point anchors use the bounding rectangle
of the main shape, which, ignore any inverted inputs or outputs, but includes any outer sep. This
only affects the compass point anchors and is not set on a shape by shape basis: whether the
bounding box is used is determined by value of this key when the anchor is accessed.
\begin{tikzpicture}[minimum height=1.5cm]
\node[xnor gate US, draw, gray!50,line width=2pt] (A) {};
\foreach \x/\y/\z in {false/blue/1pt, true/red/2pt}
\foreach \a in {north, south, east, west, north east,
south east, north west, south west}
\draw[logic gate anchors use bounding box=\x, color=\y]
(A.\a) circle(\z);
\end{tikzpicture}
The library defines a number of shapes. For each shape the allowed number of inputs is also shown:
• and gate US, two or more inputs
• and gate CDH, two or more inputs
• nand gate US, two or more inputs
• nand gate CDH, two or more inputs
• or gate US, two or more inputs
• nor gate US, two or more Inputs
• xor gate US, two inputs
• xnor gate US, two inputs
• not gate US, one input
• buffer gate US, one input
In the following, we only have a detailed look at the anchors defined by one of them. We choose the
nand gate US because it shows all the “interesting” anchors.
Shape nand gate US
This shape is a nand gate, which supports two or more inputs. If less than two inputs are specified
an error will result. The anchors for this gate with two non-inverted inputs (using the normal
compass point anchors) are shown below. Anchor 30 is an example of a border anchor.
(s.north west)
(s.north)
(s.north east)
(s.30)
(s.input 1)
(s.west)
(s.center)
(s.east)
(s.output)
(s.mid west)
(s.base west)
(s.input 2)
Nand Gate
(s.text)
(s.mid)
(s.base)
(s.mid east)
(s.base east)
(s.south east)
(s.south west)
(s.south)
562
\Huge
\begin{tikzpicture}
\node[name=s,shape=nand gate US,shape example, inner sep=0cm,
logic gate inputs={in},
logic gate inverted radius=.5cm] {Nand Gate\vrule width1pt height2cm};
\foreach \anchor/\placement in
{center/above, text/above, 30/above right,
mid/right, mid east/left, mid west/above,
base/below, base east/below, base west/left,
north/above, south/below, east/above, west/above,
north east/above, south east/below, south west/below, north west/above,
output/right, input 1/above, input 2/below}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
(For the definition of the shape example style, see Section 67.)
47.3.5
Implementation: The IEC-Style Logic Gates Shape Library
Tik Z Library shapes.gates.logic.IEC
\usepgflibrary{shapes.gates.logic.IEC}
\usepgflibrary[shapes.gates.logic.IEC]
\usetikzlibrary{shapes.gates.logic.IEC}
\usetikzlibrary[shapes.gates.logic.IEC]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library provides rectangular logic gate shapes. These shapes are suffixed with IEC as they are
based on gates recommended by the International Electrotechnical Commission.
By default each gate is drawn with a symbol, & for and and nand gates, ≥ 1 for or and nor gates, 1
for not and buffer gates, and = 1 for xor and xnor gates. These symbols are drawn automatically
(internally they are drawn using the “foreground” path), and are not strictly speaking part of the node
contents. However, the gate is enlarged to make sure the symbols are within the border of the node. It
is possible to change the symbols and their position within the node using the following keys:
(no default, initially \char‘\&)
/pgf/and gate IEC symbol=htexti
Set the symbol for the and gate. Note that if the node is filled, this color will be used for the symbol,
making it invisible, so it will be necessary set htexti to something like \color{black}\char‘\&.
Alternatively, the logic gate IEC symbol color key can be used to set the color of all symbols
simultaneously.
In Tik Z, when the use IEC style logic gates key has been used, this key can be replaced by
and gate symbol.
(no default, initially \char‘\&)
/pgf/nand gate IEC symbol=htexti
Set the symbol for the nand gate. In Tik Z, when the use IEC style logic gates key has been
used, this key can be replaced by nand gate symbol.
(no default, initially $\geq1$)
/pgf/or gate IEC symbol=htexti
Set the symbol for the or gate. In Tik Z, when the use IEC style logic gates key has been
used, this key can be replaced by or gate symbol.
(no default, initially $\geq1$)
/pgf/nor gate IEC symbol=htexti
Set the symbol for the nor gate. In Tik Z, when the use IEC style logic gates key has been
used, this key can be replaced by nor gate symbol.
(no default, initially {$=1$})
/pgf/xor gate IEC symbol=htexti
Set the symbol for the xor gate. Note the necessity for braces, as the symbol contains =. In Tik Z,
when the use IEC style logic gates key has been used, this key can be replaced by xor gate
symbol.
(no default, initially {$=1$})
/pgf/xnor gate IEC symbol=htexti
Set the symbol for the xnor gate. In Tik Z, when the use IEC style logic gates key has been
used, this key can be replaced by xnor gate symbol.
563
(no default, initially 1)
/pgf/not gate IEC symbol=htexti
Set the symbol for the not gate. In Tik Z, when the use IEC style logic gates key has been
used, this key can be replaced by not gate symbol.
(no default, initially 1)
/pgf/buffer gate IEC symbol=htexti
Set the symbol for the buffer gate. In Tik Z, when the use IEC style logic gates key has
been used, this key can be replaced by buffer gate symbol.
(no default, initially top)
/pgf/logic gate IEC symbol align=haligni
Set the alignment of the logic gate symbol (in Tik Z, when the use IEC style logic gates key
has been used, IEC can be omitted. The specification in haligni is a comma separated list from
top, bottom, left or right. The distance between the border of the node and the outer edge of
the symbol is determined by the values of the inner xsep and inner ysep.
≥1
≥1
\begin{tikzpicture}[minimum size=1cm, use IEC style logic gates]
\tikzset{every node/.style={nor gate, draw}}
\node (A) at (0,1.5) {};
\node [logic gate symbol align={bottom, right}] (B) at (0,0) {};
\foreach \g in {A, B}{
\foreach \i in {1,2}
\draw ([xshift=-0.5cm]\g.input \i) -- (\g.input \i);
\draw (\g.output) -- ([xshift=0.5cm]\g.output);
}
\end{tikzpicture}
/pgf/logic gate IEC symbol color=hcolor i
(no default)
This key sets the color for all symbols simultaneously. This color can be overridden on a case by
case basis by specifying a color when setting the symbol text.
The library defines the following shapes:
• and gate IEC, two or more inputs
• nand gate IEC, two or more inputs
• or gate IEC, two or more inputs
• nor gate IEC, two or more inputs
• xor gate IEC, two inputs
• xnor gate IEC, two inputs
• not gate IEC, one input
• buffer gate IEC, one input
Again, we only have a look at the nand-gate in more detail:
Shape nand gate IEC
This shape is a nand gate. It supports two or more inputs. If less than two inputs are specified an
error will result. The anchors for this gate with two inverted inputs are shown below. Anchor 30
is an example of a border anchor.
564
(s.north west)
(s.north)
(s.north east)
(s.30)
&
(s.input 1)
(s.west)
(s.center)
(s.east)
(s.output)
(s.mid west)
(s.text)
(s.base west)
Nand Gate
(s.mid) (s.mid east)
(s.input 2)
(s.base)
(s.base east)
(s.south west)
(s.south)
(s.south east)
\Huge
\begin{tikzpicture}
\node[name=s,shape=nand gate IEC ,shape example, inner xsep=1cm, inner ysep=1cm,
minimum height=6cm, nand gate IEC symbol=\color{black!30}\char‘\&,
logic gate inputs={in},
logic gate inverted radius=0.65cm]
{Nand Gate\vrule width1pt height2cm};
\foreach \anchor/\placement in
{center/above, text/above, 30/above right,
mid/right, mid east/left, mid west/above,
base/below, base east/below, base west/left,
north/above, south/below, east/above, west/above,
north east/above, south east/below, south west/below, north west/above,
output/right, input 1/above, input 2/below}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
47.4
47.4.1
Electrical Engineering Circuits
Overview
An electrical engineering circuit contains symbols like resistors or capacitors or voltage sources and annotations like the two arrows pointing toward an element whose behaviour is light dependent. The electrical
engineering libraries, abbreviated ee-libraries, provide such symbols and annotations.
Just as for logical gates, there are different ways of drawing ee-symbols. Currently, there is one main
library for drawing circuits, which uses the graphics from the International Electrotechnical Commission,
but you can add your own libs. This is why, just as for logical gates, there is a base library and more specific
libraries.
Tik Z Library circuits.ee
\usetikzlibrary{circuits.ee} % LATEX and plain TEX
\usetikzlibrary[circuits.ee] % ConTEXt
This library declares the ee symbols, but (mostly) does not provide the symbol graphics, which is left to
the sublibraries. Just like the logical gates library, a key is defined that is normally only used internally:
(no value)
/tikz/circuit ee
This style calls the keys circuit (which internally calls every circuit and the following style:
(style, no value)
/tikz/every circuit ee
Use this key to configure the appearance of logical circuits.
The library also declares some standard annotations and units.
565
As for logical circuits, to draw a circuit the first step is to include a library containing the symbols
graphics. Currently, you have to include circuits.ee.IEC.
Tik Z Library circuit.ee.IEC
\usetikzlibrary{circuit.ee.IEC} % LATEX and plain TEX
\usetikzlibrary[circuit.ee.IEC] % ConTEXt
When this library is loaded, you can use the following style:
(no value)
/tikz/circuit ee IEC
This style calls circuit ee and installs the IEC-like graphics for the logical symbols like resistor.
Inside the circuit ee IEC scope, you can now use the keys for symbols, units, and annotations listed
in the later sections. We have a more detailed look at one of each of them, all the others work the same way.
Let us start with an example of a symbol: the resistor symbol. The other predefined symbols are listed
in Section 47.4.2 and later sections.
(no default)
/tikz/resistor=hoptionsi
This key should be used with a node path command or with the to path command.
Using the Key with Normal Nodes. When used with a node, it will cause this node to “look like”
a resistor (by default, in the IEC library, this is just a simple rectangle).
\tikz [circuit ee IEC]
\node [resistor] {};
Unlike normal nodes, a resistor node generally should not take any text (as in node [resistor] {foo}).
Instead, the labeling of resistors should be done using the label, info and ohm options.
5Ω
\tikz [circuit ee IEC]
\node [resistor,ohm=5] {};
The hoptionsi make no real sense when the resistor option is used with a normal node, you can just
as well given them to the node itself. Thus, the following has the same effect as the above example:
5Ω
\tikz [circuit ee IEC]
\node [resistor={ohm=5}] {};
In a circuit, you will often wish to rotate elements. For this, the options point up, point down,
point left or point right may be especially useful. They are just shorthands for appropriate rotations like rotate=90.
5Ω
10kΩ
\tikz [circuit ee IEC] {
\node (R1) [resistor,point up,ohm=5] at (3,1) {};
\node (R2) [resistor,ohm=10k]
at (0,0) {};
\draw (R2) -| (R1);
}
Using the Key on a To Path. When the resistor key is used on a to path inside a circuit ee IEC,
the circuit handle symbol key is called internally. This has a whole bunch of effects:
1. The path currently being constructed is cut up to make place for a node.
2. This node will be a resistor node that is rotated so that it points “along” the path (unless an
option like shift only or an extra rotation is used to change this).
3. The hoptionsi passed to the resistor key are passed on to the node.
4. The hoptionsi are pre-parsed to identify a pos key or a key like at start or midway. These keys
are used to determine where on the to path the node will lie.
Since the hoptionsi of the resistor key are passed on to the resistor node on the path, you can use it
to add labels to the node. Here is a simple example:
566
\tikz [circuit ee IEC]
\draw (0,0) to [resistor=red]
(3,0)
to [resistor={ohm=2\mu}] (3,2);
2µΩ
You can add multiple labels to a resistor and you can have multiple resistors (or other elements) on a
single path.
Inputs, Outputs, and Anchors. Like the logical gates, all ee-symbols have an input and an output
anchor. Special-purpose-nodes may have even more anchors of this type. Furthermore, the ee-symbolsnodes also have four standard compass direction anchors.
Changing the Appearance. To configure the appearance of all resistors, see Section 47.2.6. You
can use the hoptionsi to locally change the appearance of a single resistor.
Let us now have a look at an example of a unit: the Ohm unit. The other predefined units are listed in
Section 47.4.6.
(no default)
/tikz/ohm=hvaluei
This key is used to add an info label to a node with a special text: $\mathrm{hvaluei\Omega}$. In
other words, the ohm key can only be used with the options of a node and, when used, it will cause
the hvaluei to be placed next to the node, followed by Ω. Since the hvaluei is typeset inside a \mathrm
command, when you write ohm=5k you get 5kΩ, ohm=5p yields 5pΩ, and ohm=5.6\cdot 10^{2}\mu
yields 5.6 · 102 µΩ.
\tikz [circuit ee IEC] \draw (0,0) to [resistor={ohm=5M}] (0,2);
5MΩ
Instead of ohm you can also use ohm’, which places the label on the other side.
\tikz [circuit ee IEC] \draw (0,0) to [resistor={ohm’=5M}] (0,2);
5MΩ
6fΩ
5MΩ
Finally, there are also keys ohm sloped and ohm’ sloped for having the info label rotate together with
the main node.
\tikz [circuit ee IEC]
\draw (0,0) to [resistor={ohm sloped=5M}] (0,2)
(2,0) to [resistor={ohm’ sloped=6f}] (2,2);
You can configure the appearance of an Ohm info label using the key every ohm.
Finally, let us have a look at an annotation: the light emitting annotation. The other predefined units
are listed in Section 47.4.7.
(no default)
/tikz/light emitting=hoptionsi
Like a unit, an annotation should be given as an additional option to a node. It causes some drawings
(in this case, two parallel lines) to be placed next to the node.
\tikz [circuit ee IEC] \draw (0,0) to [diode=light emitting] (2,0);
567
The hoptionsi can be used for three different things:
1. You can use keys like red to change the appearance of this annotation, locally.
2. You can use keys like <- or -latex to change the direction and kinds of arrows used in the
annotation.
3. You can use info labels like ohm=5 or info=foo inside the hoptionsi. These info labels will be added
to the main node (not to the annotation itself), but the label distance will have been changed to
accommodate for the space taken up by the annotation.
not good
better
\tikz [circuit ee IEC]
{
\draw (0,2) to [diode={light emitting,info=not good}] (2,2);
\draw (0,0) to [diode={light emitting={info=better},
info’=also good}] (2,0);
}
also good
In addition to light emitting there is also a key called light emitting’, which simply places the
annotation on the other side of the node.
You can configure the appearance of annotations in three ways:
• You can set the every circuit annotation style.
• You can set the every light emitting style.
• You can set the following key:
(style, no value)
/tikz/annotation arrow
This style should set the default > arrow to some nice value.
47.4.2
Symbols: Indicating Current Directions
There are two symbols for indicating current directions.
circuit ee.
Key
/tikz/current direction
/tikz/current direction’
These symbols are defined directly inside
Appearance
The examples have been produced by (in essence) \draw (0,0) to[hsymbol namei] (3,0);.
47.4.3
Symbols: Basic Elements
The following table show basic symbols as they are depicted inside the circuit ee IEC environment. To
install one of alternate graphics, you have to say set hsymbol namei graphic=var hsymbol namei IEC
graphic.
Key
/tikz/resistor
/tikz/inductor
/tikz/capacitor
Appearance
Alternate appearance
/tikz/battery
/tikz/bulb
/tikz/current source
/tikz/voltage source
/tikz/ground
568
47.4.4
Symbols: Diodes
The following table shows diodes as they are depicted inside the circuit ee IEC environment.
Key
/tikz/diode
/tikz/Zener diode
/tikz/Schottky diode
/tikz/tunnel diode
/tikz/backward diode
/tikz/breakdown diode
47.4.5
Appearance
Alternate appearance
Symbols: Contacts
The following table shows contacts as they are depicted inside the circuit ee IEC environment.
Key
/tikz/contact
/tikz/make contact
/tikz/break contact
47.4.6
Appearance
Alternate appearance
Units
The circuit.ee library predefines the following unit keys:
Key
/tikz/ampere
/tikz/volt
/tikz/ohm
/tikz/siemens
/tikz/henry
/tikz/farad
/tikz/coulomb
/tikz/voltampere
/tikz/watt
/tikz/hertz
47.4.7
Appearance of 1 unit
1A
1V
1Ω
1S
1H
1F
1C
1VA
1W
1Hz
Annotations
The circuit.ee.IEC library defines the following annotations:
Key
Appearance
/tikz/light emitting
/tikz/light dependent
/tikz/direction info
/tikz/adjustable
The lines have been produced using, in essence,
\draw (0,0)
to [resistor=light emitting] (2,0)
to [diode=light emitting’] (4,0);
and similarly for the other annotations.
47.4.8
Implementation: The EE-Symbols Shape Library
The Tik Z libraries depend on two shape libraries, which are included automatically. Usually, you will not
need to use these shapes directly.
569
Tik Z Library shapes.gates.ee
\usepgflibrary{shapes.gates.ee}
\usepgflibrary[shapes.gates.ee]
\usetikzlibrary{shapes.gates.ee}
\usetikzlibrary[shapes.gates.ee]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library defines basic shapes that can be used by all ee-circuit libraries. Currently, it defines the
following shapes:
• rectangle ee
• circle ee
• direction ee
Additionally, the library defines the following arrow tip: The direction ee arrow tip is basically the
same as a triangle 45 arrow tip with rounded joins.
direction ee yields thick
and thin
However, unlike normal arrow tips, its size does not depend on the current line width. Rather, it
depends on the value of its arrow options, which should be set to the desired size. Thus, you should say
something like \pgfsetarrowoptions{direction ee}{5pt} to set the size of the arrow.
Shape rectangle ee
This shape is completely identical to a normal rectangle, only there are two additional anchors: The
input anchor is an alias for the west anchor, while the output anchor is an alias for the east anchor.
Shape circle ee
Like the rectangle ee shape, only for circles.
Shape direction ee
This shape is rather special. It is intended to be used to “turn an arrow tip into a shape.” First, you
should set the following key to the name of an arrow tip:
/pgf/direction ee arrow=hright arrow tip namei
(no default)
The value of this key will be used for the arrow tip depicted in an direction ee shape.
When a node of shape direction ee is created, several things happen:
1. The size of the shape is computed according to the following rules: The width of the shape is set
up so that the left border of the shape is at the left end of the arrow tip and the right border is
at the right end of the arrow tip. These left and right “ends” of the arrow are the tip end and the
back end specified by the arrow itself (see Section 100.2 for details). You usually need not worry
about this width setting.
By comparison, the height of the arrow is given by the current setting of minimum height. Thus,
this key must have been set up correctly to reflect the “real” height of the arrow tip. The reason
is that the height of an arrow is not specified when arrows are declared and is, thus, not available,
here.
Possibly, the height computation will change in the future to reflect the real height of the arrow,
so you should generally set up the minimum height to be the same as the real height.
2. A straight line from left to right inside the shape’s boundaries is added to the background path.
3. The arrow tip, pointing right, is drawn before the background path.
The anchors of this shape are just the compass anchors, which lie on a rectangle whose width and height
are the above-computed height and width.
570
(s.north west)
(s.north)
(s.north east)
(s.30)
(s.input)
(s.center)
(s.west)
(s.east)
(s.south west)
(s.south)
(s.output)
(s.south east)
\begin{tikzpicture}
\pgfsetarrowoptions{direction ee}{6cm}
\node[name=s,shape=direction ee,shape example,minimum height=0.7654*6cm] {};
\foreach \anchor/\placement in
{center/above, 30/above right,
north/above, south/below, east/left, west/right,
north east/above, south east/below, south west/below, north west/above,
input/left,output/right}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
(s.north)
(s.input)
(s.output)
(s.south)
\begin{tikzpicture}[direction ee arrow=angle 45]
\node[name=s,shape=direction ee,shape example,minimum height=1.75cm] {};
\foreach \anchor/\placement in {north/above, south/below,
output/right, input/left}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
47.4.9
Implementation: The IEC-Style EE-Symbols Shape Library
Tik Z Library shapes.gates.ee.IEC
\usepgflibrary{shapes.gates.ee.IEC}
\usepgflibrary[shapes.gates.ee.IEC]
\usetikzlibrary{shapes.gates.ee.IEC}
\usetikzlibrary[shapes.gates.ee.IEC]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library defines shapes for depicting ee symbols according to the IEC recommendations. These
shapes will typically be used in conjunction with the graphic mechanism detailed earlier, but you can
also used them directly.
Shape generic circle IEC
This shape inherits from circle ee, which in turn is just a normal circle with additional input and
output anchors at the left and right ends. However, additionally, this shape allows you to specify a
path that should be added before the background path using the following key:
/pgf/generic circle IEC/before background=hcodei
(no default)
When a node of shape generic circle IEC is created, the current setting of this key is used as
the “before background path.” This means that after the circle’s background has been drawn/filled/whatever, the hcodei is executed.
571
When the hcodei is executed, the coordinate system will have been transformed in such a way that
the point (1pt, 0pt) lies at the right end of the circle and (0pt, 1pt) lies at the top of the circle.
(More precisely, these points will lie exactly on the middle of the radial line.)
Here is an examples of how to use this shape:
Hello world
\tikz \node [generic circle IEC,
/pgf/generic circle IEC/before background={
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpoint{1pt}{0pt}}
\pgfpathlineto{\pgfpoint{0pt}{1pt}}
\pgfpathlineto{\pgfpoint{-0.5pt}{-0.5pt}}
\pgfusepathqstroke
},
draw] {Hello world};
Shape generic diode IEC
This shape is used to depict diodes. The main shape is taken up by a “right pointing” triangle. The
anchors are positioned on the border of a rectangle around the diode, see the below example. The
diode’s size is based on the current settings of minimum width and minimum height.
(s.north west)
(s.north)
(s.north east)
(s.30)
(s.input)
(s.center)
(s.west)
(s.south west)
(s.east)
(s.south)
(s.output)
(s.south east)
\begin{tikzpicture}
\node[name=s,shape=generic diode IEC,shape example,minimum size=6cm] {};
\foreach \anchor/\placement in
{center/above, 30/above right,
north/above, south/below, east/left, west/right,
north east/above, south east/below, south west/below, north west/above,
input/left,output/right}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
This shape, like the generic circle IEC shape, is generic in the sense that there is a special key that
is used for the before background drawings:
/pgf/generic diode IEC/before background=hcodei
(no default)
Similarly to the generic circle IEC shape, when a node of shape generic diode IEC is created,
the current setting of this key is used as the “before background path.” When the hcodei is executed,
the coordinate system will have been transformed in such a way that the origin is at the “tip” of
the diode’s triangle, the point (0pt, 1pt) is exactly half the diode’s height above this origin, and the
point (1pt, 0pt) is half the diode’s height to the right of the origin.
The idea is that you use this key to draw different kinds of diode endings.
572
\tikz \node [minimum size=1cm,generic diode IEC,
/pgf/generic diode IEC/before background={
\pgfpathmoveto{\pgfqpoint{-.5pt}{-1pt}}
\pgfpathlineto{\pgfqpoint{.5pt}{-1pt}}
\pgfpathmoveto{\pgfqpoint{0pt}{-1pt}}
\pgfpathlineto{\pgfqpoint{0pt}{1pt}}
\pgfpathmoveto{\pgfqpoint{-.5pt}{1pt}}
\pgfpathlineto{\pgfqpoint{.5pt}{1pt}}
\pgfusepathqstroke
},
draw] {};
Shape breakdown diode IEC
This shape is used to depict a bidirectional breakdown diode. The diode’s size is based on the current
settings of minimum width and minimum height.
(s.north west)
(s.north)
(s.north east)
(s.30)
(s.input)
(s.center)
(s.west)
(s.south west)
(s.east)
(s.south)
(s.output)
(s.south east)
\begin{tikzpicture}
\node[name=s,shape=breakdown diode IEC,shape example,minimum width=6cm,minimum height=4cm] {};
\foreach \anchor/\placement in
{center/above, 30/above right,
north/above, south/below, east/left, west/right,
north east/above, south east/below, south west/below, north west/above,
input/left,output/right}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape var resistor IEC
This shape is used to depict a variant version of a resistor. Its size is computed as for a rectangle (thus,
its size depends things like the minimum height). Then, inside this rectangle, a background path is set
up according to the following rule: Starting from the left end, zigzag segments are added to the path.
Each segment consists of a line at a 45 degree angle going up to the top of the rectangle, then going
down to the bottom, then going up to mid height of the node. As many segments as possible are put
inside as possible. The last segment is then connected to the output anchor via a straight line.
All of this means that, in general, the shape should be much wider than high.
(s.north west)
(s.input)
(s.north)
(s.30)
(s.north east)
(s.center)
(s.west)
(s.south west)
(s.east)
(s.south)
(s.output)
(s.south east)
573
\begin{tikzpicture}
\node[name=s,shape=var resistor IEC,shape example,minimum width=7cm,minimum height=1cm] {};
\foreach \anchor/\placement in
{center/above, 30/above right,
north/above, south/below, east/left, west/right,
north east/above, south east/below, south west/below, north west/above,
input/left,output/right}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape inductor IEC
This shape is used to depict an inductor, using a bumpy line. Its size is computed as follows: Any text
and inner sep are ignored (and should normally not be given). The minimum height plus (twice) the
outer ysep specify the distance between the north and south anchors, similarly for the minimum width
plus the outer xsep for the east and west. The bumpy line is drawn starting from the lower left corner
to the lower right corner with bumps being half-circles whose height is exactly the minimum height.
The center of the shape is just above the south anchor, at a distance of the outer ysep.
(s.north west)
(s.input)
(s.north)
(s.30)
(s.north east)
(s.west)
(s.east)
(s.output)
(s.center)
(s.south west)
(s.south)
(s.south east)
\begin{tikzpicture}
\node[name=s,shape=inductor IEC,shape example,minimum width=7cm,minimum height=1cm] {};
\foreach \anchor/\placement in
{center/above, 30/above right,
north/above, south/below, east/left, west/right,
north east/above, south east/below, south west/below, north west/above,
input/left,output/right}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Just as for a var resistor IEC, as many bumps as possible are added and the last bump is connected
to the output anchor via a straight line.
Shape capacitor IEC
This shape is based on a rectangle ee. However, instead of a rectangle as the background path, only
the “left and right lines” that make up the rectangle are drawn.
(s.north west)
(s.north)
(s.north east)
(s.30)
(s.input)
(s.center)
(s.west) (s.east)
(s.output)
(s.south west)
(s.south)
(s.south east)
574
\begin{tikzpicture}
\node[name=s,shape=capacitor IEC,shape example,
minimum width=2cm,minimum height=3cm,inner sep=0pt] {};
\foreach \anchor/\placement in
{center/above, 30/above right,
north/above, south/below, east/left, west/right,
north east/above, south east/below, south west/below, north west/above,
input/left,output/right}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape battery IEC
This shape is similar to a capacitor IEC, however, the right line is only half the height of the left
line.
\tikz \node[shape=battery IEC,shape example,minimum size=2cm,
inner sep=0pt] {};
Shape ground IEC
This shape is similar to a batter IEC, only three lines of different heights are drawn.
\tikz \node[shape=ground IEC,shape example,minimum size=2cm,
inner sep=0pt] {};
Shape make contact IEC
This shape consists of a line going from the lower left corner to the upper right corner. The size and
anchors of this shape are computed in the same way as for an inductor IEC.
(s.north west) (s.north) (s.north east)
(s.30)
(s.input)
(s.west)
(s.east)
(s.center)
(s.output)
(s.south west) (s.south) (s.south east)
\begin{tikzpicture}
\node[name=s,shape=make contact IEC,shape example,minimum width=3cm,minimum height=1cm] {};
\foreach \anchor/\placement in
{center/above, 30/above right,
north/above, south/below, east/left, west/right,
north east/above, south east/below, south west/below, north west/above,
input/left,output/right}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape var make contact IEC
This shape works like make contact IEC, only a little circle is added to the path at the lower left
corner. The radius of this circle is one twelfth of the width of the node.
575
\tikz \node[shape=var make contact IEC,shape example,
minimum height=1cm,minimum width=3cm,inner sep=0pt] {};
Shape break contact IEC
This shape depicts a contact that can be broken. It works like make contact IEC.
\tikz \node[shape=break contact IEC,shape example,
minimum height=1cm,minimum width=3cm,inner sep=0pt] {};
576
48
Decoration Library
48.1
Overview and Common Options
The decoration libraries define a number of (more or less useful) decorations that can be applied to paths.
The usage of decorations is not covered in the present section, please consult Sections 24, which explains
how decorations are used in Tik Z, and 98, which explains how new decorations can be defined.
The decorations are influenced by a number of parameters that can be set using the decoration option.
These parameters are typically shared between different decorations. In the following, the general options
are documented (they are defined directly in the decoration module), special-purpose keys are documented
with the decoration that uses it.
Since you are encouraged to use these keys to make your own decorations configurable, it is indicated
for each key where the value is stored (so that you can access it). Note that some values are stored in TEX
dimension registers while others are stored in macros.
(no default, initially 2.5pt)
/pgf/decoration/amplitude=hdimensioni
This key determines the “desired height” (or amplitude) of decorations for which this makes sense. For
instance, the initial value of 2.5pt means that deforming decorations should deform a path by up to
2.5pt away from the original path.
This key sets the TEX-dimension \pgfdecorationsegmentamplitude.
(no default, initially 2.5pt)
/pgf/decoration/meta-amplitude=hdimensioni
This key determines the amplitude for a meta-decoration.
The key sets the TEX-macro (!) \pgfmetadecorationsegmentamplitude.
(no default, initially 10pt)
/pgf/decoration/segment length=hdimensioni
Many decorations are made up of small segments. This key determines the desired length of such
segments.
This key sets the TEX-dimension \pgfdecorationsegmentlength.
/pgf/decoration/meta-segment length=hdimensioni
(no default, initially 1cm)
This determined the length of the meta-segments from which a meta-decoration is made up.
This key sets the TEX-macro (!) \pgfmetadecorationsegmentlength.
(no default, initially 45)
/pgf/decoration/angle=hdegreei
The way some decorations look like depends on a configurable angle. For instance, a wave decoration
consists of arcs and the opening angle of these arcs is given by the angle.
This key sets the TEX-macro \pgfdecorationsegmentangle.
/pgf/decoration/aspect=hfactor i
(no default, initially 0.5)
For some decorations there is a natural aspect ratio. For instance, for a brace decoration the aspect
ratio determines where the brace point will be.
This key sets the TEX-macro \pgfdecorationsegmentaspect.
(no default, initially 2.5pt)
/pgf/decoration/start radius=hdimensioni
For some decorations there is a natural start radius (of some circle, presumably).
This key stores the value directly inside the key.
(no default, initially 2.5pt)
/pgf/decoration/end radius=hdimensioni
For some decorations there is a natural end radius (of some circle, presumably).
This key stores the value directly inside the key.
(style, no default)
/pgf/decoration/radius=hdimensioni
Sets the start and end radius simultaneously.
(no default, initially false)
/pgf/decoration/path has corners=hbooleani
577
This is a hint to the decoration code as to whether the path has corners or not. If a path has a sharp
corner, setting this option to true may result in better rendering of the decoration because the joins of
input segments are approached “more carefully” than when this key is set to false. However, if the path
is, say, a smooth circle, setting this key to true will usually look worse. Most decorations ignore this
key, anyway. Internally, it sets the TEX-if \ifpgfdecoratepathhascorners.
48.2
Path Morphing Decorations
Tik Z Library decorations.pathmorphing
\usepgflibrary{decorations.pathmorphing}
\usepgflibrary[decorations.pathmorphing]
\usetikzlibrary{decorations.pathmorphing}
\usetikzlibrary[decorations.pathmorphing]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
A path morphing decoration “morphs” or “deforms” the to-be-decorated path. This means that what
used to be a straight line might afterwards be a snaking curve and have bumps. However, a line is still
a line and path deforming decorations do not change the number of subpaths. For instance, if the path
used to consist of two circles and an open arc, the path will, after the decoration process, still consist
of two closed subpaths and one open subpath.
48.2.1
Decorations Producing Straight Line Paths
The following deformations use only straight lines in order to morph the paths.
Decoration lineto
This decoration replaces the path by straight lines. For each curve, the path simply goes directly from
the start point to the end point. In the following example, the arc actually consist of two subcurves.
This decoration is actually always defined when the decoration module is loaded, but it is documented
here for consistency.
\begin{tikzpicture}[decoration=lineto]
\draw [help lines] grid (3,2);
\draw [decorate,fill=yellow!80!black]
(0,0) -- (3,1) arc (0:180:1.5 and 1) -- cycle;
\end{tikzpicture}
Decoration straight zigzag
This (meta-)decoration decorates the path by alternating between curveto and zigzag decorations. It
always finishes with the curveto decoration. The following parameters influence the decoration:
• amplitude determines how much the zigzag line raises above and falls below a straight line to the
target point.
• segment length determines the length of a complete “up-down” cycle.
• meta-segment length determines the length of the curveto and the zigzag decorations.
\begin{tikzpicture}[decoration={straight zigzag,meta-segment length=1.1cm}]
\draw [help lines] grid (3,2);
\draw [decorate,fill=yellow!80!black]
(0,0) -- (3,1) arc (0:180:1.5 and 1) -- cycle;
\end{tikzpicture}
Decoration random steps
This decoration consists of straight line segments. The line segments head towards the target, but each
step is randomly shifted a little bit. The following parameters influence the decorations:
• segment length determines the basic length of each step.
578
• amplitude The end of each step is perturbed both in x- and in y-direction by two values drawn
uniformly from the interval [−d, d], where d is the value of amplitude.
\begin{tikzpicture}
[decoration={random steps,segment length=2mm}]
\draw [help lines] grid (3,2);
\draw [decorate,fill=yellow!80!black]
(0,0) -- (3,1) arc (0:180:1.5 and 1) -- cycle;
\end{tikzpicture}
Decoration saw
This decoration looks like the blade of a saw. The following parameters influence the decoration:
• amplitude determines how much each spike raises above the straight line.
• segment length determines the length each spike.
\begin{tikzpicture}[decoration=saw]
\draw [help lines] grid (3,2);
\draw [decorate,fill=yellow!80!black]
(0,0) -- (3,1) arc (0:180:1.5 and 1) -- cycle;
\end{tikzpicture}
Decoration zigzag
This decoration looks like a zigzag line. The following parameters influence the decoration:
• amplitude determines how much the zigzag line raises above and falls below a straight line to the
target point.
• segment length determines the length of a complete “up-down” cycle.
\begin{tikzpicture}[decoration=zigzag]
\draw [help lines] grid (3,2);
\draw [decorate,fill=yellow!80!black]
(0,0) -- (3,1) arc (0:180:1.5 and 1) -- cycle;
\end{tikzpicture}
48.2.2
Decorations Producing Curved Line Paths
Decoration bent
This decoration adds a slightly bent line from the start to the target. The amplitude of the bend is
given amplitude (an amplitude of zero gives a straight line).
• amplitude determines the amplitude of the bend.
• aspect determines how tight the bend is. A good value is around 0.3.
Note that this decoration makes only little sense for curves. You should apply it only to straight lines.
\begin{tikzpicture}[decoration=bent]
\draw [help lines] grid (3,2);
\draw [decorate] (0,0) -- (3,1) -- (1.5,2) -- (0,1);
\end{tikzpicture}
B
A
\begin{tikzpicture}[decoration={bent,aspect=.3}]
\draw [decorate,fill=yellow!80!black] (0,0) rectangle (3.5,2);
\node[circle,draw] (A) at (.5,.5) {A};
\node[circle,draw] (B) at (3,1.5) {B};
\draw[->,decorate] (A) -- (B);
\draw[->,decorate] (B) -- (A);
\end{tikzpicture}
579
Decoration bumps
This decoration replaces the path by little half ellipses. The following parameters influence it.
• amplitude determines the height of the half ellipse.
• segment length determines the width of the half ellipse.
\begin{tikzpicture}[decoration=bumps]
\draw [help lines] grid (3,2);
\draw [decorate,fill=yellow!80!black]
(0,0) -- (3,1) arc (0:180:1.5 and 1) -- cycle;
\end{tikzpicture}
Decoration coil
This decoration replaces the path by a coiled line. To understand how this works, imagine a threedimensional spring. The spring’s axis points along the path toward the target. Then, we “view” the
spring from a certain angle. If we look “straight from the side” we will see a perfect sine curve, if we
look “more from the front” we will see a coil. The following parameters influence the decoration:
• amplitude determines how much the coil rises above the path and falls below it. Thus, this is the
radius of the coil.
• segment length determines the distance between two consecutive “curls.” Thus, when the spring
is see “from the side” this will be the wave length of the sine curve.
• aspect determines the “viewing direction.” A value of 0 means “looking from the side” and a value
of 0.5, which is the default, means “look more from the front.”
\begin{tikzpicture}[decoration=coil]
\draw [help lines] grid (3,2);
\draw [decorate,fill=yellow!80!black]
(0,0) -- (3,1) arc (0:180:1.5 and 1) -- cycle;
\end{tikzpicture}
\begin{tikzpicture}
[decoration={coil,aspect=0.3,segment length=3mm,amplitude=3mm}]
\draw [help lines] grid (3,2);
\draw [decorate,fill=yellow!80!black]
(0,0) -- (3,1) arc (0:180:1.5 and 1) -- cycle;
\end{tikzpicture}
Decoration curveto
This decoration simply yields a line following the original path. This means that (ideally) it does not
change the path and follows any curves in the path (hence the name). In reality, due to the internals of
how decorations are implemented, this decoration actually replaces the path by numerous small straight
lines.
This decoration is mostly useful in conjunction with meta-decorations. It is also actually defined in the
decoration module and is always available.
\begin{tikzpicture}[decoration=curveto]
\draw [help lines] grid (3,2);
\draw [decorate,fill=yellow!80!black]
(0,0) -- (3,1) arc (0:180:1.5 and 1) -- cycle;
\end{tikzpicture}
Decoration snake
This decoration replaces the path by a line that looks like a snake seen from above. More precisely, the
snake is a sine wave with a “softened” start and ending. The following parameters influence the snake:
580
• amplitude determines the sine wave’s amplitude.
• segment length determines the sine wave’s wavelength.
\begin{tikzpicture}[decoration=snake]
\draw [help lines] grid (3,2);
\draw [decorate,fill=yellow!80!black]
(0,0) -- (3,1) arc (0:180:1.5 and 1) -- cycle;
\end{tikzpicture}
48.3
Path Replacing Decorations
Tik Z Library decorations.pathreplacing
\usepgflibrary{decorations.pathreplacing}
\usepgflibrary[decorations.pathreplacing]
\usetikzlibrary{decorations.pathreplacing}
\usetikzlibrary[decorations.pathreplacing]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library defines decorations that replace the to-be-decorated path by another path. Unlike morphing
decorations, the replaced path might be quite different, for instance a straight line might be replaced
by a set of circles. Note that filling a path that has been replaced using one of the decorations in this
library typically does not fill the original area but, rather, the smaller area of the newly-created path
segments.
Decoration border
This decoration adds straight lines to the path that are at a specific angle to the line toward the target.
The idea is to add these little lines to indicate the “border” of an area. The following parameters
influence the decoration:
• segment length determines the distance between consecutive ticks.
• amplitude determines the length of the ticks.
• angle determines the angle between the ticks and the line of the path.
\begin{tikzpicture}[decoration=border]
\draw [help lines] grid (3,2);
\draw [postaction={decorate,draw,red}]
(0,0) -- (3,1) arc (0:180:1.5 and 1);
\end{tikzpicture}
Decoration brace
This decoration replaces a straight line path by a long brace. The left and right end of the brace will be
exactly on the start and endpoint of the decoration. The decoration really only makes sense for paths
that are a straight line.
• amplitude determines how much the brace rises above the path.
• aspect determines the fraction of the total length where the “middle part” of the brace will be.
\begin{tikzpicture}[decoration=brace]
\draw [help lines] grid (3,2);
\draw [decorate] (0,0) -- (3,1);
\end{tikzpicture}
Decoration expanding waves
This decoration adds arcs to the path that get bigger along the line towards the target. The following
parameters influence the decoration:
581
• segment length determines the distance between consecutive arcs.
• angle determines the opening angle below and above the path. Thus, the total opening angle is
twice this angle.
\begin{tikzpicture}[decoration={expanding waves,angle=5}]
\draw [help lines] grid (3,2);
\draw [decorate] (0,0) -- (3,1) arc (0:180:1.5 and 1);
\end{tikzpicture}
Decoration moveto
This decoration simply jumps to the end of the path using a move-to path operation. It is mainly useful
as pre=moveto or post=moveto decorations.
This decoration is actually always defined when the decoration module is loaded, but it is documented
here for consistency.
Decoration ticks
This decoration replaces the path by straight lines that are orthogonal to the path. The following
parameters influence the decoration:
• segment length determines the distance between consecutive ticks.
• amplitude determines half the length of the ticks.
\begin{tikzpicture}[decoration=ticks]
\draw [help lines] grid (3,2);
\draw [decorate] (0,0) -- (3,1) arc (0:180:1.5 and 1);
\end{tikzpicture}
Decoration waves
This decoration replaces the path by arcs that have a constant size. The following parameters influence
the decoration:
• segment length determines the distance between consecutive arcs.
• angle determines the opening angle below and above the path. Thus, the total opening angle is
twice this angle.
• radius determines the radius of each arc.
\begin{tikzpicture}[decoration={waves,radius=4mm}]
\draw [help lines] grid (3,2);
\draw [decorate] (0,0) -- (3,1) arc (0:180:1.5 and 1);
\end{tikzpicture}
Decoration show path construction
This decoration allows “something different” to be done for each type of input segment (i.e., moveto,
lineto, curveto or closepath). Typically, each segment will be replaced with another path, but this need
not necessarily be the case.
582
cu
closepath
o
et
rv
cu
moveto
to
line
rv
et
o
\begin{tikzpicture}[>=stealth, every node/.style={midway, sloped, font=\tiny},
decoration={show path construction,
moveto code={
\fill [red] (\tikzinputsegmentfirst) circle (2pt)
node [fill=none, below] {moveto};},
lineto code={
\draw [blue,->] (\tikzinputsegmentfirst) -- (\tikzinputsegmentlast)
node [above] {lineto};
},
curveto code={
\draw [green!75!black,->] (\tikzinputsegmentfirst) .. controls
(\tikzinputsegmentsupporta) and (\tikzinputsegmentsupportb)
..(\tikzinputsegmentlast) node [above] {curveto};
},
closepath code={
\draw [orange,->] (\tikzinputsegmentfirst) -- (\tikzinputsegmentlast)
node [above] {closepath};}
}]
\draw [help lines] grid (3,2);
\path [decorate] (0,0) -- (3,1) arc (0:180:1.5 and 1) -- cycle;
\end{tikzpicture}
The following keys can be used to specify the code to execute for each type of input segment.
(no default, initially {})
/pgf/decoration/moveto code=hcodei
Set the code to be executed for every moveto input segment. It is important to remember that the
transformations applied by the decoration automaton are turned off when hcodei is executed.
(no default, initially {})
/pgf/decoration/lineto code=hcodei
Set the code to be executed for every lineto input segment.
/pgf/decoration/curveto code=hcodei
Set the code to be executed for every curveto input segment.
(no default, initially {})
/pgf/decoration/closepath code=hcodei
(no default, initially {})
Set the code to be executed for every closepath input segment.
Within hcodei the first and last points on the current input segment can be accessed using \pgfpointdecoratedinputsegmentfirst and \pgfpointdecoratedinputsegmentlast. For curves, the control
(support) points can be accessed using \pgfpointdecoratedinputsegmentsupporta and \pgfpointdecoratedinputsegmentsupportb.
In Tik Z, you can use the following macros inside a Tik Z coordinate.
\tikzinputsegmentfirst
The first point on the current input segment path.
\tikzinputsegmentlast
The last point on the current input segment path.
\tikzinputsegmentsupporta
The first support on the curveto input segment path.
\tikzinputsegmentsupportb
The second support on the curveto input segment path.
583
\tikzset{
show curve controls/.style={
decoration={
show path construction,
curveto code={
\draw [blue, dashed]
(\tikzinputsegmentfirst)
-- (\tikzinputsegmentsupporta)
node [at end, cross out, draw, solid, red, inner sep=2pt]{};
\draw [blue, dashed]
(\tikzinputsegmentsupportb) -- (\tikzinputsegmentlast)
node [at start, cross out, draw, solid, red, inner sep=2pt]{};
}
},decorate
}
}
\tikzpicture
\draw [postaction=show curve controls, thick]
(0,2) .. controls (2.5,1.5) and (0.5,0.5) .. (3,0);
\endtikzpicture
48.4
48.4.1
Marking Decorations
Overview
A marking on a path is any kind of graphic that is placed on a specific position on a path. Markings are
useful in rather diverse situations: you can use them to, say, place little “footsteps” along a path as if someone
where walking along the path; to place arrow tips on the middle of a path to indicate the “direction” in which
something is flowing; or you can use them to place informative information at certain positions of a path.
For historical reasons there are three different libraries for placing marks on a path. They differ in what
kind of markings can be added to a path. We start with the most general and most useful of these libraries.
48.5
Arbitrary Markings
Tik Z Library decorations.markings
\usepgflibrary{decorations.markings}
\usepgflibrary[decorations.markings]
\usetikzlibrary{decorations.markings}
\usetikzlibrary[decorations.markings]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
Markings are arbitrary “marks” that can be put on a path. Marks can be arrow tips or nodes or even
whole pictures.
Decoration markings
A marking can be thought of a “little picture” or more precisely of “some scope contents” that is placed
“on” a path at a certain position. Suppose the marking should be a simple cross. We can produce this
with the following code:
\draw (-2pt,-2pt) -- (2pt,2pt);
\draw (2pt,-2pt) -- (-2pt,2pt);
If we use this code as a marking at position 2cm on a path, then the following happens: pgf determines
the position on the path that is 2cm along the path. Then is translates the coordinate system to this
position and rotates it such that the positive x-axis is tangent to the path. Then a protective scope is
created, inside which the above code is executed – resulting in a little cross on the path.
The markings decoration allows you to place one or more such markings on a path. The decoration
destroys the input path (except in certain cases, detailed later), which means that it uses the path for
determining positions on the path, but after the decoration is done this path is gone. You typically
need to use a postaction to add markings.
Let us start with the above example in real code:
584
\begin{tikzpicture}[decoration={
markings,% switch on markings
mark=% actually add a mark
at position 2cm
with
{
\draw (-2pt,-2pt) -- (2pt,2pt);
\draw (2pt,-2pt) -- (-2pt,2pt);
}
}
]
\draw [help lines] grid (3,2);
\draw [postaction={decorate}] (0,0) -- (3,1) arc (0:180:1.5 and 1);
\end{tikzpicture}
We can also add the cross repeatedly:
\begin{tikzpicture}[decoration={
markings,% switch on markings
mark=% actually add a mark
between positions 0 and 1 step 5mm
with
{
\draw (-2pt,-2pt) -- (2pt,2pt);
\draw (2pt,-2pt) -- (-2pt,2pt);
}
}
]
\draw [help lines] grid (3,2);
\draw [postaction={decorate}] (0,0) -- (3,1) arc (0:180:1.5 and 1);
\end{tikzpicture}
The mark decoration option is used to specify a marking. It comes in two versions:
/pgf/decoration/mark=at position hposiwithhcodei
(no default)
The options specifies that when a marking decoration is applied, there should be a marking at
position hposi on the path whose code is given by hcodei.
The hposi can have four different forms:
1. It can be a non-negative dimension like 0pt or 2cm or 5cm/2. In this case, it refers to the
position along the path that is this far displaced from the start.
2. It can be a negative dimension like -1cm-2pt or -1sp. In this case, the position is taken from
the end of the path. Thus, -1cm is the position that is −1cm displaced from the end of the
path.
3. It can be a dimensionless non-negative number like 1/2 or 0.333+2*0.1. In this case, the hposi
is interpreted as a factor of the total path length. Thus, a hposi or 0.5 refers to the middle of
the path, 0.1 is near the start, and so on.
4. It can be a dimensionless negative number like -0.1. Then, again, the fraction of the path
length counts “from the end.”
The hposi determines a position on the path. When the marking is applied, the (high level)
coordinate system will have been transformed so that the origin lies at this position and the positive
x-axis points along the path. For this coordinate system, the hcodei is executed. It can contain all
sorts of graphic drawing commands, including (even named) nodes.
If the position lies past the end of the path (for instance if hposi is set to 1.2), the marking will
not be drawn.
It is possible to give the mark option several times, which causes several markings to be applied. In
this case, however, it is necessary that the positions on the path are in increasing order. That is, it
is not allowed (and will result in chaos) to have a marking that lies earlier on the path to follow a
marking that is later on the path.
585
1cm
fro
m
mid
end
1cm
\begin{tikzpicture}[decoration={
markings,% switch on markings
mark=at position 1cm with \node[red]{1cm};,
mark=at position .5
with \node[green]{mid};,
mark=at position -1cm with {\node[blue,transform shape]{1cm from end};}}
]
\draw [help lines] grid (3,2);
\draw [postaction={decorate}] (0,0) -- (3,1) arc (0:180:1.5 and 1);
\end{tikzpicture}
Here is an example that shows how markings can be used to place text on plots:
f (x)
f (x) = x
f (x) =
f (x) = sin x
1 x
20 e
x
\begin{tikzpicture}[domain=0:4,label/.style={postaction={
decorate,
decoration={
markings,
mark=at position .75 with \node #1;}}}]
\draw[very thin,color=gray] (-0.1,-1.1) grid (3.9,3.9);
\draw[->] (-0.2,0) -- (4.2,0) node[right] {$x$};
\draw[->] (0,-1.2) -- (0,4.2) node[above] {$f(x)$};
\draw[red,label={[above left]{$f(x)=x$}}]
plot (\x,\x);
\draw[blue,label={[below left]{$f(x)=\sin x$}}]
plot (\x,{sin(\x r)});
\draw[orange,label={[right]{$f(x)= \frac{1}{20} \mathrm e^x$}}] plot (\x,{0.05*exp(\x)});
\end{tikzpicture}
When the hcodei is being executed, two special keys will have been set up, whose value may be of
interest:
/pgf/decoration/mark info/sequence number
(no value)
This key can only be read. Its value (which can be obtained using the \pgfkeysvalueof
command) is a “sequence number” of the mark. The first mark that is added to a path has
number 1, the second number 2, and so on. This key is mainly useful in conjunction with
repeated markings (see below).
/pgf/decoration/mark info/distance from start
(no value)
This key can only be read. Its value is the distance of the marking from the start of the path
in points. For instance, if the path length is 100pt and the marking is in the middle of the
path, the value of this key would be 50.0pt.
A second way to use the mark key is the following:
/pgf/decoration/mark=betweenpositions hstart posi and hend posi step hsteppingi with hcodei
(no default)
This works similarly to the at position version of this option, only multiple marks are placed,
starting at hstart posi and then spaced apart by hsteppingi. The hstart posi, the hend posi, and
also the hsteppingi may all be specified in the same way as for the at position version, that is,
either using units or no units and also using positive or negative values.
586
Let us start with a simple example in which we place ten crosses along a path starting with the
beginning of the path (hstart posi = 0) and ending at the end (hend posi = 1).
\begin{tikzpicture}[decoration={markings,
mark=between positions 0 and 1 step 0.1
with { \draw (-2pt,-2pt) -- (2pt,2pt);
\draw (2pt,-2pt) -- (-2pt,2pt); }} ]
\draw [help lines] grid (3,2);
\draw [postaction={decorate}] (0,0) -- (3,1) arc (0:180:1.5 and 1);
\end{tikzpicture}
In the next example we place arrow shapes on the path instead of crosses. Note the use of the
transform shape option to ensure that the nodes are actually rotated.
\begin{tikzpicture}[decoration={markings,
mark=between positions 0 and 1 step 1cm
with { \node [single arrow,fill=red,
single arrow head extend=3pt,transform shape] {};}}]
\draw [help lines] grid (3,2);
\draw [postaction={decorate}] (0,0) -- (3,1) arc (0:180:1.5 and 1);
\end{tikzpicture}
Using the key sequence number we can also “number” the nodes and even refer to them later
on.
6
7
5
8
4
3
2
1
\begin{tikzpicture}[decoration={markings,
mark=between positions 0 and 1 step 1cm with {
\node [draw,
name=mark-\pgfkeysvalueof{/pgf/decoration/mark info/sequence number},
transform shape]
{\pgfkeysvalueof{/pgf/decoration/mark info/sequence number}};}}]
\draw [help lines] grid (3,2);
\draw [postaction={decorate}] (0,0) -- (3,1) arc (0:180:1.5 and 1);
\draw [red,->] (mark-3) -- (mark-7);
\end{tikzpicture}
In the following example we use the distance info to place “length information” on a path:
120.0pt
80.0pt
40.0pt
0.0pt
160.0pt
200.0pt
225.24788pt
\begin{tikzpicture}[decoration={markings,
% Main marks
mark=between positions 0 and 1 step 40pt with
{ \draw [help lines] (0,0) -- (0,0.5)
node[above,font=\tiny]{
\pgfkeysvalueof{/pgf/decoration/mark info/distance from start}}; },
mark=at position -0.1pt with
{ \draw [help lines] (0,0) -- (0,0.5)
node[above,font=\tiny]{
\pgfkeysvalueof{/pgf/decoration/mark info/distance from start}}; }}]
\draw [help lines] grid (5,3);
\draw [postaction={decorate}] (0,0) .. controls (8,3) and (0,3) .. (5,0) ;
\end{tikzpicture}
/pgf/decoration/reset marks
(no value)
Since mark options accumulate, there needs to be a way to “reset” things, so that any mark options
set in an enclosing scope do not interfere. This option does exactly this. Note that when the hcodei
of a marking is executed, the markings are automatically reset.
As mentioned earlier, the decoration usually destroys the path. However, this is no longer the case when
the following key is set:
587
/pgf/decoration/mark connection node=hnode namei
(no default, initially empty)
When this key is set to a non-empty hnode namei while the decoration is being processed, the
following happens: The marking code should, among possibly other things, define a node named
hnode namei. Then, the output path of this decoration will contain a line-to to “one end” of this
node, followed by a moveto to the “other end” of the node. More precisely, the first end is given
by the position on the border of hnode namei that lies in the direction “from which the path heads
toward the node” while the other end lies on the border “where the path heads away from the
node.” Furthermore, this option causes the decoration to end with a line-to to the end instead of
a move-to.
The net effect of all this is that when you decorate a straight line with one or more markings that
contain just a node, the line will effectively connect these nodes.
Here are two examples that show how this works:
no
my
my node
48.5.1
de
\begin{tikzpicture}[decoration={markings,
mark connection node=my node,
mark=at position .5 with
{\node [draw,blue,transform shape] (my node) {my node};}}]
\draw [help lines] grid (3,2);
\draw decorate { (0,0) -- (3,2) };
\end{tikzpicture}
\begin{tikzpicture}[decoration={markings,
mark connection node=my node,
mark=at position .25 with
{\node [draw,red] (my node) {my node};}}]
\draw [help lines] grid (3,2);
\draw decorate { (0,0) -- (3,2) };
\end{tikzpicture}
Arrow Tip Markings
Frequent markings that are hard to create correctly are arrow tips. For them, two special commands are
available when the hcodei of a mark option is executed. (They are only defined in this code):
\arrow[hoptionsi]{harrow end tipi}
This command simply draws the harrow end tipi at the origin, pointing right. This is exactly what you
need when you want to draw an arrow tip as a marking.
The hoptionsi can only be given when Tik Z is used. In this case, they are executed in a scope that
contains the arrow tip.
1cm
\begin{tikzpicture}[decoration={
markings,% switch on markings
mark=at position 1cm with {\node[red]{1cm};},
mark=at position .75 with {\arrow[blue,line width=2mm]{>}},
mark=at position -1cm with {\arrowreversed[black]{stealth}}}
]
\draw [help lines] grid (3,2);
\draw [postaction={decorate}] (0,0) -- (3,1) arc (0:180:1.5 and 1);
\end{tikzpicture}
Here is a more useful example:
\begin{tikzpicture}[decoration={
markings,% switch on markings
mark=between positions 0 and .75 step 4mm with {\arrow{stealth}},
mark=between positions .75 and 1 step 4mm with {\arrowreversed{stealth}}}
]
\draw [help lines] grid (3,2);
\draw [postaction={decorate}] (0,0) -- (3,1) arc (0:180:1.5 and 1);
\end{tikzpicture}
\arrowreversed[hoptionsi]{harrow end tipi}
As above, only the arrow end tip is flipped and points in the other direction.
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48.5.2
Footprint Markings
Tik Z Library decorations.footprints
\usepgflibrary{decorations.footprints}
\usepgflibrary[decorations.footprints]
\usetikzlibrary{decorations.footprints}
\usetikzlibrary[decorations.footprints]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
The decorations of this library can be used to decorate a path with little footprints, as if someone had
“walked” along the path.
Decoration footprints
The footprint decoration adds little footprints around the path. They start with the left foot.
\begin{tikzpicture}[decoration={footprints,foot length=5pt,stride length=10pt}]
\draw [help lines] grid (3,3);
\fill [decorate] (0,0) -- (3,2) arc (0:180:1.5 and 1);
\end{tikzpicture}
You can influence the way this decoration looks using the following options:
(initially 10pt)
/pgf/decoration/foot length
The length or size of the footprint itself. A larger value makes the footprint larger, but does not
change the stride length.
\begin{tikzpicture}[decoration={footprints,foot length=20pt}]
\fill [decorate] (0,0) -- (3,0);
\end{tikzpicture}
(initially 30pt)
/pgf/decoration/stride length
The length of strides. This is the distance between the beginnings of left footprints along the
path.
\begin{tikzpicture}[decoration={footprints,stride length=50pt}]
\fill [decorate] (0,0) -- (3,0);
\end{tikzpicture}
(initially 4pt)
/pgf/decoration/foot sep
The separation in the middle between the footprints. The footprints are moved away from the path
by half this amount.
\begin{tikzpicture}[decoration={footprints,foot sep=10pt}]
\fill [decorate] (0,0) -- (3,0);
\end{tikzpicture}
(initially 10)
/pgf/decoration/foot angle
Footprints are rotated by this much.
\begin{tikzpicture}[decoration={footprints,foot angle=60}]
\fill [decorate] (0,0) -- (3,0);
\end{tikzpicture}
(initially human)
/pgf/decoration/foot of
The species whose footprints are shown. Possible values are:
589
Species
Result
gnome
human
bird
felis silvestris
48.5.3
Shape Background Markings
The third library for adding markings uses the background paths of certain shapes. This library is included
mostly for historical reasons, using the markings library is usually preferable.
Tik Z Library decorations.shapes
\usepgflibrary{decorations.shapes}
\usepgflibrary[decorations.shapes]
\usetikzlibrary{decorations.shapes}
\usetikzlibrary[decorations.shapes]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library defines decorations that use shapes or shape-like drawings to decorate a path. The following
options are common options used by the decorations in this library:
(no default, initially 2.5pt)
/pgf/decoration/shape width=hdimensioni
The desired width of the shapes. For decorations that support varying shape sizes, this key sets
both the start and end width (which can be overwritten using options like shape start width).
/pgf/decoration/shape height=hdimensioni
(no default, initially 2.5pt)
Works like the previous key, only for the height.
(no default)
/pgf/decoration/shape size=hdimensioni
Sets the desired width and height simultaneously.
For the exact places and macros where these keys store the values, please consult the beginning of the
code of the library.
Decoration crosses
This decoration replaces the path by (diagonal) crosses. The following parameters influence the decoration:
• segment length determines the distance between (the centers of) consecutive crosses.
• shape height determines the height of each cross.
• shape width determines the width of each cross.
\begin{tikzpicture}[decoration=crosses]
\draw [help lines] grid (3,2);
\draw [decorate] (0,0) -- (3,1) arc (0:180:1.5 and 1);
\end{tikzpicture}
590
Decoration triangles
This decoration replaces the path by triangles that point along the path. The following parameters
influence the decoration:
• segment length determines the distance between consecutive triangles.
• shape height determines the height of the triangle side that is orthogonal to the path.
• shape width determines the width of the triangle.
\begin{tikzpicture}[decoration=triangles]
\draw [help lines] grid (3,2);
\draw [decorate,fill=yellow!80!black] (0,0) -- (3,1) arc (0:180:1.5 and 1);
\end{tikzpicture}
Decoration shape backgrounds
This is a general decoration that replaces the to-be-decorated path by repeated copies of the background
path of an arbitrary shape that has previously been defined using the \pgfdeclareshape command (that
is, you can use any shape in the shape libraries).
Please note that the background path of the shapes is used, but no nodes are created. This means that
you cannot have text inside the shapes of this path, you cannot name them, or refer to them. Finally,
this decoration will not work with shapes that depend strongly on the size of the text box (like the arrow
shapes). If any of these restrictions pose a problem, use the markings library instead.
\begin{tikzpicture}[decoration={shape backgrounds,shape=star,shape size=5pt}]
\draw [help lines] grid (3,2);
\draw [decorate] (0,0) -- (3,1) arc (0:180:1.5 and 1);
\end{tikzpicture}
\tikzset{paint/.style={ draw=#1!50!black, fill=#1!50 },
decorate with/.style=
{decorate,decoration={shape backgrounds,shape=#1,shape size=2mm}}}
\begin{tikzpicture}
\draw [decorate with=dart,
paint=red]
(0,1.5) -- (3,1.5);
\draw [decorate with=diamond,
paint=green] (0,1)
-- (3,1);
\draw [decorate with=rectangle, paint=blue]
(0,0.5) -- (3,0.5);
\draw [decorate with=circle,
paint=yellow] (0,0)
-- (3,0);
\end{tikzpicture}
All shapes are positioned by the anchor that is specified via the anchor decoration option:
/pgf/decoration/anchor=hanchor i
(no default, initially center)
The anchor used to position the shape backgrounds.
A shape background path is added at the start point of the path and, if the distance between the shapes
is appropriate, at the end point of the path.
\begin{tikzpicture}[decoration={
shape backgrounds,shape=regular polygon,shape size=4mm}]
\draw [help lines] grid (3,2);
\draw [thick] (0,0) -- (2,2) (1,0) -- (3,0);
\draw [red, decorate, decoration={shape sep=.5cm}] (1,0) -- (3,0);
\draw [blue, decorate, decoration={shape sep=.5cm}] (0,0) -- (2,2);
\end{tikzpicture}
Keys for customizing specific shapes can be specified (e.g., star points, cloud puffs, kite angles,
and so on). The size of the shape is “enforced” using transformations. This means that the shape is
typeset with an empty text box and some default size values, resulting in an initial shape. This shape
is then rescaled using coordinate transformations so that it has the desired size (which may vary as we
591
travel along the to-be-decorated path). This means that settings involving angles and distances may not
appear entirely accurate. More general options such as inner sep and minimum size will be ignored,
but transformations can be applied to each segment as described below.
\tikzset{
paint/.style={draw=#1!50!black, fill=#1!50},
my star/.style={decorate,decoration={shape backgrounds,shape=star},
star points=#1}
}
\begin{tikzpicture}[decoration={shape sep=.5cm, shape size=.5cm}]
\draw [my star=9, paint=red]
(0,1.5) -- (3,1.5);
\draw [my star=5, paint=blue]
(0,.75) -- (3,.75);
\draw [my star=5, paint=yellow, shape border rotate=30] (0,0) -- (3,0);
\end{tikzpicture}
There are various keys to control the drawing of the shape decoration.
/pgf/decoration/shape=hshape namei
(no default, initially circle)
The shape whose background path is used.
(no default, initially .25cm, between centers)
/pgf/decoration/shape sep=hspacingi
Set the spacing between the shapes on the decorations path. This can be just a distance on its own,
but the additional keywords between centers, and between borders (which must be preceded
by a comma), specify that the distance is between the center anchors of the shapes or between the
edges of the boundaries of the shape borders.
\begin{tikzpicture}[
decoration={shape backgrounds,shape size=.5cm,shape=signal},
signal from=west, signal to=east,
paint/.style={decorate, draw=#1!50!black, fill=#1!50}]
\draw [help lines] grid (3,2);
\draw [paint=red, decoration={shape sep=.5cm}]
(0,2) -- (3,2);
\draw [paint=green, decoration={shape sep={1cm, between centers}}]
(0,1) -- (3,1);
\draw [paint=blue, decoration={shape sep={1cm, between borders}}]
(0,0) -- (3,0);
\end{tikzpicture}
/pgf/decoration/shape evenly spread=hnumber i
(no default)
This key overrides the shape sep key and forces the decoration to fit hnumber i shapes evenly across
the path. If hnumber i is less than 1, then no shapes will be used. If hnumber i equals 1, then one
shape is put in the middle of the path. The additional keywords by centers (the default, if no
keyword is specified) and by borders can be used (both preceded by a comma), to specify how
the distance between shapes is determined. These keywords will only have a noticeable effect if the
shapes sizes differ over time.
\tikzset{
paint/.style={draw=#1!50!black, fill=#1!50},
spreading/.style={
decorate,decoration={shape backgrounds, shape=rectangle,
shape start size=4mm,shape end size=1mm,shape evenly spread={#1}}}
}
\begin{tikzpicture}
\fill [paint=green,spreading={5, by borders},
decoration={shape scaled}]
(0,2)
-- (3,2);
\fill [paint=blue,spreading={5, by centers},
decoration={shape scaled}]
(0,1.5) -- (3,1.5);
\fill [paint=red,
spreading=5]
(0,1)
-- (3,1);
\fill [paint=orange, spreading=4]
(0,.5) -- (3,.5);
\fill [paint=gray,
spreading=1]
(0,0)
-- (3,0);
\end{tikzpicture}
(no default, initially true)
/pgf/decoration/shape sloped=hbooleani
592
By default, shapes are rotated to the slope of the decorations path. If hbooleani is the value false,
then this rotation is turned off. Internally this sets the TEX-if \ifpgfshapedecorationsloped
accordingly.
\tikzset{
paint/.style={draw=#1!50!black, fill=#1!50}
}
\begin{tikzpicture}[decoration={
shape width=.65cm, shape height=.45cm,
shape=isosceles triangle, shape sep=.75cm,
shape backgrounds}]
\draw [help lines] grid (3,2);
\draw [paint=red,decorate] (0,0) -- (2,2);
\draw [paint=blue,decorate,decoration={shape sloped=false}]
(1,0) -- (3,2);
\end{tikzpicture}
It is possible to scale the width and height of the shapes along the length of the decorations path. The
shapes are scaled between the starting size and the ending size. The following keys customize the way
the decoration shapes are scaled:
(no default, initially false)
/pgf/decoration/shape scaled=hbooleani
\tikzset{
bigger/.style={decoration={shape start size=.125cm, shape end size=.5cm}},
smaller/.style={decoration={shape start size=.5cm, shape end size=.125cm}},
decoration={shape backgrounds,
shape sep={.25cm, between borders},shape scaled}
}
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\fill [decorate, bigger, red!50]
(0,1) -- (3,2);
\fill [decorate, smaller, blue!50] (0,0) -- (3,1);
\end{tikzpicture}
If this key is set to false (which is the default), then only the start width and height are used. Note
that the keys shape width and shape height set the start and end height simultaneously.
/pgf/decoration/shape start width=hlengthi
(no default, initially 2.5pt)
The starting width of the shape.
/pgf/decoration/shape start height=hlengthi
(no default, initially 2.5pt)
The starting height of the shape.
/pgf/decoration/shape start size=hlengthi
(style, no default)
Sets both the start height and start width simultaneously.
(no default, initially 2.5pt)
/pgf/decoration/shape end width=hlengthi
The recommended ending width of the shape. Note that this is the width that a shape will take
only if it is drawn exactly at the end of the path.
\tikzset{
bigger/.style={decoration={shape start size=.25cm, shape end size=1cm}},
smaller/.style={decoration={shape start size=1cm, shape end size=.25cm}},
decoration={shape backgrounds,
shape sep={.25cm, between borders},shape scaled}
}
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\fill [decorate,bigger,
decoration={shape sep={.25cm, between borders}}, blue!50]
(0,1.5) -- (3,1.5);
\fill [decorate,smaller,
decoration={shape sep={1cm, between centers}},
red!50]
(0,.5) -- (3,.5);
\draw [gray, dotted] (0,1.625) -- (3,2)
(0,1.375) -- (3,1)
(0,1)
-- (3,.625) (0,0)
-- (3,.375);
\end{tikzpicture}
593
(no default)
/pgf/decoration/shape end height=hlengthi
The recommended ending height of the shape.
(style, no default)
/pgf/decoration/shape end size=hlengthi
Set both the end height and end width simultaneously.
48.6
Text Decorations
Tik Z Library decorations.text
\usepgflibrary{decorations.text}
\usepgflibrary[decorations.text]
\usetikzlibrary{decorations.text}
\usetikzlibrary[decorations.text]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
The decoration in this library decorates the path with some text. This can be used to draw text that
follows a curve.
Decoration text along path
This decoration decorates the path with text. This drawing of the text is a “side effect” of the decoration.
The to-be-decorated path is only used to determine where the characters should be put and it is thrown
away after the decoration is done. This is why no line is shown in the following example.
gar
id
c
icu
lously long
ur
ve
xt
g te
n
o
l
e
So m
alo n
\catcode‘\|12
\begin{tikzpicture}[decoration={text along path,
text={Some long text along a ridiculously long curve that}}]
\draw [help lines] grid (3,2);
\draw [decorate] (0,0) -- (3,1) arc (0:180:1.5 and 1);
\end{tikzpicture}
pgf “does its best” to typeset the text, however you should note the following points:
• Each character in the text is typeset in a separate \hbox. This means that if you want fancy things
like kerning or ligatures you will have to manually annotate the characters in the decoration text
within a group, for example, W{\kern-1ptA}TER.
• Each character is positioned using the center of its baseline. To move the text vertically (relative
to the path), the additional transform key should be used.
• No attempt is made to ensure characters do not overlap when the angle between segments is
considerably less than 180◦ (this is tricky to do in TEX without a huge processing overhead). In
general this should not be too much of a problem, but, once again, kerning can be used in most
cases to overcome any undesirable effects.
• It is only possible to typeset text in math mode under considerable restrictions. Math mode is
entered and exited using any character of category code 3 (e.g., in plain TEX this is $). Math
subscripts and superscripts need to be contained within braces (e.g., {^y_i}) as do commands like
\times or \cdot. However, even modestly complex mathematical typesetting is unlikely to be
successful along a path (or even desirable).
• Some inaccuracies in positioning may be particularly apparent at input segment boundaries. This
can (unfortunately) only be solved on a case-by-case basis by individually kerning the offending
characters within a group.
The following keys are used by the text decoration:
(no default, initially empty)
/pgf/decoration/text=htexti
Sets the text to typeset along the curve. Consecutive spaces are ignored, so \ (or \space in LATEX)
should be used to insert multiple spaces. It is possible to format the text using normal formatting
commands, such as \it, \bf and \color, within customizable delimiters. Initially these delimiters
are both | (however, care will be needed regarding the category codes of delimiters — see below).
594
a big
.
le
n juicy app
gree
\catcode‘\|12
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\path [decorate,decoration={text along path,
text={a big |\color{green}|green|| juicy apple.}}]
(0,0) .. controls (0,2) and (3,0) .. (3,2);
\end{tikzpicture}
By following the first delimiter with +, the formatting commands are added to any existing formatting.
.
ple
a
big
red juicy ap
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\path [decorate,decoration={text along path,
text={a |\large|big |+\bf\color{red}|red|| juicy apple.}}]
(0,0) .. controls (0,2) and (3,0) .. (3,2);
\end{tikzpicture}
Internally, the text is stored in the macro \pgfdecorationtext. Any characters that have not been
typeset when the end of the path has been reached will be stored in \pgfdecorationrestoftext.
/pgf/decoration/text format delimiters={hbeforei}{hafter i}
(no default, initially {|}{})
pp
le.
Set the characters that the text decoration will use to parse formatting commands. If hafter i is
empty, then hbeforei will be used for both delimiters. In general you should stick to characters
whose category codes are 11 or 12. As + is used to indicate that the specified format commands
are added to any existing ones, you should avoid using + as a delimiter.
A big
en a
red and gre
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\path [decorate, decoration={text along path,text format delimiters={[}{]},
text={A big [\color{red}]red[] and [\color{green}]green[] apple.}}]
(0,0) .. controls (0,2) and (3,0) .. (3,2);
\end{tikzpicture}
/pgf/decoration/text color=hcolor i
(no default, initially black)
The color of the text.
(no default, initially false)
/pgf/decoration/reverse path=hbooleani
u
j
a big
a big
j
apple
icy
icy
apple
u
This key reverses the path. This is especially useful for typesetting text along different sides of
curves.
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\draw [gray, ->]
[postaction={decoration={text along path,
text={a big juicy apple}, text color=red}, decorate}]
[postaction={decoration={text along path,
text={a big juicy apple}, text color=blue, reverse path}, decorate}]
(3,0) .. controls (3,2) and (0,2) .. (0,0);
\end{tikzpicture}
/pgf/decoration/text align={halignment optionsi}
(no default)
This changes the key path to /pgf/decoration/text align and executes halignment optionsi.
/pgf/decoration/text align/align=halignmenti
(no default, initially left)
Aligns the text according to halignmenti, which should be one of left, right, or center.
a big j
uic
y
e
appl
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\draw [red, dashed]
[postaction={decoration={text along path, text={a big juicy apple},
text align={align=right}}, decorate}]
(0,0) .. controls (0,2) and (3,2) .. (3,0);
\end{tikzpicture}
595
(style, no value)
/pgf/decoration/text align/left
Aligns the text to the left end of the path.
/pgf/decoration/text align/right
Aligns the text to the right end of the path.
(style, no value)
/pgf/decoration/text align/center
(style, no value)
Aligns the text to the center of the path.
/pgf/decoration/text align/left indent=hlengthi
(no default, initially 0pt)
Specifies a distance which the automaton should move along before it starts typesetting the text.
/pgf/decoration/text align/right indent=hlengthi
(no default, initially 0pt)
Specifies a distance before the end of the path, where the automaton should stop typesetting the
text.
/pgf/decoration/text align/fit to path=hbooleani
(no default, initially false)
This key makes the decoration automaton try to fit the text to the length of the path. The
automaton shifts forward by a small amount between each character in order to fit the text to the
path. If, however, the length of the text is longer than the length of the path (i.e., the automaton
would have to shift backwards between characters) this key will have no effect.
a
ple
bi
p
juicy a
g
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\draw [red, dashed]
[postaction={decoration={text along path, text={a big juicy apple},
text align=fit to path}, decorate}]
(0,0) .. controls (0,2) and (3,2) .. (3,0);
\end{tikzpicture}
/pgf/decoration/text align/fit to path stretching spaces=hbooleani
false)
(no default, initially
b
This key works like the previous key except the automaton shifts forward only for space characters
(including \space, but excluding \ ).
ig
juicy
a
e
appl
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\draw [red, dashed]
[postaction={decoration={text along path, text={a big juicy apple},
text align={fit to path stretching spaces}}, decorate}]
(0,0) .. controls (0,2) and (3,2) .. (3,0);
\end{tikzpicture}
Decoration text effects along path
This decoration is similar to the text along path decoration except that each character is inserted
into the picture as a Tik Z node, and node options (such as text, scale and opacity) can be used to
create ‘text effects’.
p
s al
ong
pa
!ht
a
!
th
eff
eff
ect
g
n
o
l
a st c
t
e
t
x
tte
ex
\bfseries\large
\begin{tikzpicture}[decoration={text effects along path,
text={text effects along path!}, text align=center,
text effects/.cd,
character count=\i, character total=\n,
characters={evaluate={\c=\i/\n*100;}, text along path, text=red!\c!orange},
character widths={text along path, xslant=0, yscale=1}}]
\path [postaction={decorate}, preaction={decorate,
text effects={characters/.append={yscale=-1.5, opacity=0.5,
text=gray, xslant=(\i/\n-0.5)*3}}}]
(0,0) .. controls ++(2,1) and ++(-2,-1) .. (3,4);
\end{tikzpicture}
596
There are some important differences between this decoration and the text along path decoration:
• formatting (e.g., font and color) cannot be specified in the decoration text. They can only be
specified using the keys described below.
• as a consequence of using the Tik Z node options, this decoration is only available in Tik Z.
• due to the number of computations involved, this is quite a slow decoration.
The following keys are shared with the text along path decoration:
(no default)
/pgf/decoration/text={htexti}
Set the text this decoration will use. Braces can be used to group multiple characters together,
or commands that should not be expanded until they are typset, for example gr{\"o}{\ss}eren.
You should not use the formatting delimiters or math mode characters that the text along path
decoration supports.
(no default)
/pgf/decoration/text align=haligni
This sets the alignment of the text along the path. The haligni argument should be left, right
or center. Spreading the text out, or stretching the spaces between words is not supported.
The decoration text can be thought of as consisting of characters arranged in to sequences of letters
to make words which are separated by a word separator. This, however, does not mean that you are
limited to using only natural language as the decoration text.
0 0 0 - 0 0 1 - 0 1 0 - 0 1 1 - 1 0 0 - 1 0 1 - 1 1 0 - 1 1 1
\begin{tikzpicture}[decoration={text effects along path,
text={000-001-010-011-100-101-110-111},
text effects/.cd,
path from text,
word separator=-,
every letter/.style={shape=rectangle, fill=blue!20, draw=blue!40}}]
\path [decorate] (0,0);
\end{tikzpicture}
In addition, it is possible to replace characters with Tik Z code:
\begin{tikzpicture}[decoration={text effects along path,
text={000-001-010-011-100-101-110-111}, text align=center,
text effects/.cd,
word separator=-,
replace characters=0 with {\fill [purple] circle [radius=2pt]; },
replace characters=1 with {\fill [orange] circle [radius=2pt]; },
replace characters=- with {\path circle [radius=2pt]; },
every letter/.style={shape=rectangle, fill=blue!20, draw=blue!40}}]
\path [decorate] (0,0) .. controls ++(2,0) and ++(-2,0) .. (3,4);
\end{tikzpicture}
There are many keys and styles that can be used to add effects to the decoration text. Many of these
keys have the parent path /pgf/decoration/text effects/, but for convenience, these keys can be
accessed using the following key:
/tikz/text effects={hoptionsi}
(no default)
Execute every option in {hoptionsi} with the key path for each option temporarily set to /pgf/decoration/text effects/.
The following keys can be used to customise the appearance of text in the text effects along path
decoration.
/pgf/decoration/text effects/every character
(style, no value)
Set the effects that will be applied to every character in the decoration text. The effects will
typically be Tik Z node options. Initially, this style is empty so the decoration simply positions
597
nodes at the appropriate position along the path. In order to make the text ‘follow the path’ like
the text along path decoration the following key can be added to the every character style.
(style, no value)
/pgf/decoration/text effects/text along path
This style automatically sets the Tik Z keys transform shape (to make the character slope with
the path), anchor=baseline (to make the baseline of the characters ‘sit’ on the path) and
inner xsep=0pt (to horizontally fit each node to the character it contains, reducing the spacing
between characters).
g
on
al
th!
pa
e c
ts
c
f
e
f
eff
e
text
t
x
e
t
\begin{tikzpicture}[decoration={text effects along path,
text={text effects along path!}}]
\path [draw=red, dotted, postaction={decorate}]
(0,0) .. controls ++(1,0) and ++(-1,0) .. (3,2);
\path [draw=blue, dotted, yshift=1cm, postaction={decorate},
text effects={text along path}]
(0,0) .. controls ++(1,0) and ++(-1,0) .. (3,2);
\end{tikzpicture}
(no default)
/pgf/decoration/text effects/characters={heffectsi}
Shorthand for the every character.
/pgf/decoration/text effects/character hnumber i
(style, no value)
Specify additional effects for the character hnumber i.
(style, no value)
/pgf/decoration/text effects/every letter
Specify additional effects for every letter (i.e., every character that isn’t the word separator) in the
decoration text.
/pgf/decoration/text effects/letter hnumber i
(style, no value)
Specify the effects for letter hnumber i in every word.
(style, no value)
/pgf/decoration/text effects/every first letter
Specify additional effects for the first letter in every word.
(style, no value)
/pgf/decoration/text effects/every last letter
Specify additional effects for the last letter in every word.
(style, no value)
/pgf/decoration/text effects/every word
Specify additional effects for every word in the decoration text.
/pgf/decoration/text effects/word hnumber i
(style, no value)
Specify additional effects for word hnumber i in the decoration text.
/pgf/decoration/text effects/word hm i letter hn i
(style, no value)
Specify additional effects for letter hni in word hmi in the decoration text.
/pgf/decoration/text effects/every word separator
(style, no value)
Specify additional effects for every character that is a word separator.
/pgf/decoration/text effects/word separator=hcharacter i
(no default, initially space)
Specify the character that is to be used as the word separator. This must be a single character
such as a or - or the special value space (which should be used to indicate that spaces should be
used as the separator).
By default, the width for each character is calculated according to the bounding box of the node in
which it is contained. However, if the node is rotated or slanted, or has a substantial inner sep, this
bounding box will be quite big. The following key enables different effects to be applied to the node
that is used to calculate the width.
598
(style, no value)
/pgf/decoration/text effects/every character width
This style is appplied to the (invisible) nodes used for calculating the width of a character node.
(no default)
/pgf/decoration/text effects/character widths={heffectsi}
Shorthand for the every character width style.
tex
ff
te
x
t e
ect
t
lo
sa
e
ng
th
pa
\begin{tikzpicture}[decoration={text effects along path,
text={text effects along path!}, text align=center,
text effects/.cd,
character count=\i,
characters={xslant=0.5, text along path, name=c-\i}}]
!
e c
f
f
\path [decorate] (0,0) -- (3,2);
\path [decorate,
text effects={character widths={inner xsep=0pt, xslant=0}}]
(0,1) -- (3,3);
\end{tikzpicture}
It is possible to parametrize effects, perhaps for doing calculations, or labelling nodes based on the
number of the character in the decoration text. To access the number of the character, and the total
number of characters the following keys can be used. However, these keys should not be used inside the
style keys given above.
(no default)
/pgf/decoration/text effects/character count=hmacroi
Store the number of the character being typeset in hmacroi.
1
2 3
4
5
t e x t
6
7
e f
8
9 10 11 12
f e c t s
13
14 15 16 17 18
a l o n g
19
20 21 22 23 24
p a t h
!
\begin{tikzpicture}[decoration={text effects along path,
text={text effects along path!},
text effects/.cd,
path from text,
character count=\i, every word separator/.style={fill=red!30},
characters={text along path, shape=circle, fill=gray!50}}]
\path [decorate, text effects={characters/.append={label=above:\footnotesize\i}}] (0,0);
\end{tikzpicture}
(no default)
/pgf/decoration/text effects/character total=hmacroi
Store the total number of the characters in the decoration text in hmacroi. This key can be used
with the character count key to produce some quite pleasing effects:
\begin{tikzpicture}[decoration={text effects along path,
text={text effects along path!},
text effects/.cd,
character count=\i, character total=\n,
characters={text along path, evaluate={\c=\i/\n*100;},
text=orange!\c!blue, scale=\i/\n+0.5}}]
h!
at
s
text
t
ec
g
on
al
p
eff
\path [decorate]
(0,0) .. controls ++(1,0) and ++(-1,0) .. (3,2);
\end{tikzpicture}
(no default)
/pgf/decoration/text effects/letter count=hmacroi
Store the number of letter being typeset (i.e., the position of the character in the word) in hmacroi.
Numbering starts at 1 and the character acting as a word separator is numbered 0.
1
2 3
4
t e x t
0
1
2
e f
3
4 5
6
7
f e c t s
0
1
2
3 4
5
a l o n g
599
0
4
5
p a t h
!
1
2
3
\begin{tikzpicture}[decoration={text effects along path,
text={text effects along path!},
text effects/.cd,
path from text, letter count=\i, every word separator/.style={fill=red!30},
characters={text along path, shape=circle, fill=gray!50}}]
\path [decorate, text effects={characters/.append={label=above:\footnotesize\i}}] (0,0);
\end{tikzpicture}
(no default)
/pgf/decoration/text/effetcs/letter total=hmacroi
Store the number of letters in the current word in hmacroi. When the character is the word
separator, this value is 0.
(no default)
/pgf/decoration/text effects/word count=hmacroi
Store the number of words in the decoration text in hmacroi. Numbering starts at 1. When the
character is the word separator, hmacroi takes the number of the previous word. If the decoration
text starts with a word separator hmacroi will be 0.
1
1 1
1
t e x t
1
2
2
e f
2
2 2
2
2
f e c t s
2
3
3
3 3
3
a l o n g
3
4
4
p a t h
!
4
4
4
\begin{tikzpicture}[decoration={text effects along path,
text={text effects along path!},
text effects/.cd,
path from text, word count=\i, every word separator/.style={fill=red!30},
characters={text along path, shape=circle, fill=gray!50}}]
\path [decorate, text effects={characters/.append={label=above:\footnotesize\i}}] (0,0);
\end{tikzpicture}
/pgf/decoration/text effects/word total=hmacroi
(no default)
Store the total number of words in the decoration text in hmacroi.
It is also possible to apply effects to specific characters such as coloring every instance of the character
a, or changing the font of every T in the decoration text:
/pgf/decoration/text effects/style characters={hcharactersi} with {heffectsi}
(no default)
This key enables heffectsi to be applied to every character in the decoration text that is specified
in hcharactersi.
Falsches Üben von Xylophonmusik quält jeden größeren Zwerg
\begin{tikzpicture}[decoration={text effects along path,
text={Falsches {\"U}ben von Xylophonmusik qu{\"a}lt jeden gr{\"o}{\ss}eren Zwerg},
text effects/.cd,
path from text,
style characters=aeiou{\"U}{\"a}{\"o} with {text=blue},
characters={text along path}}]
\path [decorate] (0,0);
\end{tikzpicture}
/pgf/decoration/text effects/path from text={htrue or falsei}
(default true)
When this key is set to true and the decorated path consists only of a single point, the decoration
will calculate the width of the decoration text using all the specified parameters as if the decorated
path was actually a straight line starting from the given point. This ‘virtual’ straight line is then
decorated with the text.
600
text
effects
along
path!
\begin{tikzpicture}[decoration={text effects along path,
text={text effects along path!},
text effects/.cd,
path from text,
character count=\i, character total=\n,
characters={text along path, scale=\i/\n+0.5}}]
\path [decorate] (0,0);
\end{tikzpicture}
/pgf/decoration/text effects/path from text angle=hanglei
(no default)
cts
alo
ng
pa
th!
When used in conjunction with the path from text key, the straight line that is used as the
decorated path is rotated by hanglei around the starting point.
\begin{tikzpicture}[decoration={text effects along path,
text={text effects along path!},
text effects/.cd,
path from text, path from text angle=60,
character count=\i, character total=\n,
characters={text along path, scale=\i/\n+0.5}}]
te x
te
ff e
\path [decorate] (0,0);
\end{tikzpicture}
/pgf/decoration/text effects/fit text to path=htrue or falsei
(default true)
s al
ong
path
t e x t eff
ect
text effects
along
path
!
!
This key will make the decoration increase the space between characters so that the entire path is
used by the decoration.
\begin{tikzpicture}[decoration={text effects along path,
text={text effects along path!},
text effects/every character/.style={text along path}}]
\path [draw=gray, postaction={decorate},
(0,0) .. controls ++(2,0) and ++(-1,0)
\path [draw=gray, postaction={decorate},
text effects={fit text to path}]
(0,0) .. controls ++(2,0) and ++(-1,0)
\end{tikzpicture}
rotate=90]
.. (5,-1);
rotate=90, yshift=-1cm,
.. (5,-1);
/pgf/decoration/text effects/scale text to path=htrue or falsei
(default true)
alon
g pat
h!
text effec
ts
text effects
along
path
!
This key will make the decoration scale the text so that the entire path is used by the decoration.
\begin{tikzpicture}[decoration={text effects along path,
text={text effects along path!},
text effects/every character/.style={text along path}}]
\path [draw=gray, postaction={decorate},
(0,0) .. controls ++(2,0) and ++(-1,0)
\path [draw=gray, postaction={decorate},
text effects={scale text to path}]
(0,0) .. controls ++(2,0) and ++(-1,0)
\end{tikzpicture}
601
rotate=90]
.. (5,-1);
rotate=90, yshift=-1cm,
.. (5,-1);
/pgf/decoration/text effects/reverse text
(no value)
Reverse the order of the characters in the decoration text. This may be useful if using ‘right-to-left‘
languages. Unfortunately, any leading ‘soft’ spaces in the original text will be lost.
ffe
ce
!htap
ol
gn
a
xet
t
st
\begin{tikzpicture}[decoration={text effects along path,
text={text effects along path!},
text effects/.cd,
path from text, path from text angle=60,
reverse text,
character count=\i, character total=\n,
characters={text along path, scale=\i/\n+0.5}}]
\path [decorate] (0,0) .. controls ++(1,0) and ++(-1,0) .. (3,2);
\end{tikzpicture}
ap
!h t
et
e ff
stc
ola
ap
\begin{tikzpicture}[decoration={text effects along path,
text={text effects along path!},
text effects/.cd,
path from text, path from text angle=60,
character count=\i, character total=\n,
characters={text along path, scale=\i/\n+0.5}}]
\path [decorate, text effects={reverse text}] (0,0);
\path [blue, decorate, decoration={reverse path},
text effects={characters/.append={scale=-1}}] (1,0);
\end{tikzpicture}
!ht
gn
ola
gn
stc
eff
et
xet
xet
It is important to note that the reverse text key reverses the text before doing anything else.
This means that the numbering of characters, letters and words will still still be in the normal
order, so any parametrized effects will have to take this into account. Alternatively, to get the
numbering to follow the reversed text, it is possible to reverse the path and then invert the scale:
/pgf/decoration/text effects/group letters
(no value)
eff
te x
tex
t
te
ff
ect
sa
lo n
gp
ath
ect
sa
!
lon
gp
ath
!
Group sequences of letters together so they are treated as a single ‘character’.
\begin{tikzpicture}[decoration={text effects along path,
text={text effects along path!},
text effects/.cd,
path from text, path from text angle=60,
every word separator/.style={fill=none},
character count=\i, character total=\n,
characters={text along path, fill=gray!50, scale=\i/\n+0.5}}]
\path [decorate] (0,0);
\path [decorate, text effects={group letters,
characters/.append={fill=red!20}}]
(1,0);
\end{tikzpicture}
\begin{tikzpicture}[decoration={text effects along path,
text={text effects along path!},
text effects/.cd,
path from text, path from text angle=60,
every word separator/.style={fill=none},
character count=\i, character total=\n,
characters={text along path, fill=gray!50, scale=\i/\n+0.5}}]
ng
alo
th!
pa
!ht
ap
gn
ola
stc
eff
e
txe
eff
t
ect
st
ext
The order in which the reverse text and group letters keys are applied is important:
\path [decorate, text effects={reverse text, group letters}] (0,0);
\path [decorate, text effects={group letters, reverse text,
characters/.append={fill=red!20}}] (1,0);
\end{tikzpicture}
/pgf/decoration/text effects/repeat text=htimesi
(no default)
Usually, when the decoration runs out of text, it simply stops. This key will make the decoration
repeat the decoration text for the specified number of htimesi. If no value is given the text will
602
be repeated until the path is finished. There are two points to remember however. Firstly the
numbering of characters, letters and words will be restarted each time the text is repeated. Secondly,
the options for alignment, scaling or fitting the text to the path, fitting the path to the text, and
so on, are computed using the decoration text before the decoration starts. If any of these options
are given the behaviour of the repeat text key is undefined, but typically it will be ignored.
x
te
ef f e c
effect
t
tex
ts al
s
ct
xt
ffects along
te
g path!
p
a
n
lo
text ef
fe
path
!
!
ath
long
sa
te
effects
ext
! t th !
a
text ef
fe
t
t
ec
cts
path!
ext
g
ef
on
al long path f
s a on g
p
al
on
\begin{tikzpicture}[decoration={text effects along path,
text={text effects along path!\ },
text effects/.cd,
repeat text,
character count=\m, character total=\n,
characters={text along path, scale=0.5+\m/\n/2}}]
\path [draw=gray, ultra thin, postaction=decorate]
(180:2) \foreach \a in {0,...,12}{ arc (180-\a*90:90-\a*90:1.5-\a/10) };
\end{tikzpicture}
/pgf/decoration/text effects/character command=hmacroi
(no default)
eff
ect
s2
alo
ng
3
pa
th!
4
This key specifies a command that is executed when each character is placed in the node. The
hmacroi should be an ordinary TEX macro which takes one argument. The argument will be a
macro which when expanded will contain the current character.
\def\mycommand#1{#1$_\n$}
\begin{tikzpicture}[decoration={text effects along path,
text={text effects along path!},
text effects/.cd,
path from text, path from text angle=60, group letters,
word count=\n,
every word/.style={character command=\mycommand},
characters={text along path}}]
tex
t1
\path [decorate] (0,0);
\end{tikzpicture}
/pgf/decoration/text effects/replace characters=hcharactersi with {hcodei}
(no default)
t
xt
ff
cts
lo n
gp
th!
Replace the node for each character in hcharactersi with hcodei. The hcodei can be thought of
as describing a little picture or marking which will be used instead of the character node. The
origin will be the current point along the decoration path. Any transformations associated with the
hcharactersi (e.g., applied with the every character or every letter styles) will also be applied
to hcodei.
48.7
\begin{tikzpicture}[decoration={text effects along path,
text={text effects along path!},
text effects/.cd,
path from text, path from text angle=60,
replace characters=e with {\fill [red!20]
(0,1mm) circle [radius=1mm];},
replace characters=a with {\fill [black!20] (0,1mm) circle [radius=1mm];},
character count=\i, character total=\n,
characters={text along path, scale=\i/\n+0.5}}]
\path [decorate] (0,0);
\end{tikzpicture}
Fractal Decorations
Tik Z Library decorations.fractals
\usepgflibrary{decorations.fractals}
\usepgflibrary[decorations.fractals]
\usetikzlibrary{decorations.fractals}
\usetikzlibrary[decorations.fractals]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
The decorations of this library can be used to create fractal lines. To use them, you typically have to
apply the decoration repeatedly to an originally straight path.
603
Decoration Koch curve type 1
This decoration replaces a straight line by a “rectangular bump.” By repeatedly applying this replacement, different levels of the Koch curve fractal can be created. Its Hausdorff dimension is log 5/ log 3.
\begin{tikzpicture}[decoration=Koch curve type 1]
\draw decorate{ (0,0) -- (3,0) };
\draw decorate{ decorate{ (0,-1.5) -- (3,-1.5) }};
\draw decorate{ decorate{ decorate{ (0,-3) -- (3,-3) }}};
\end{tikzpicture}
Decoration Koch curve type 2
This decoration replaces a straight line by a “rectangular sine.” Its Hausdorff dimension is 3/2.
\begin{tikzpicture}[decoration=Koch curve type 2]
\draw decorate{ (0,0) -- (3,0) };
\draw decorate{ decorate{ (0,-2) -- (3,-2) }};
\draw decorate{ decorate{ decorate{ (0,-4) -- (3,-4) }}};
\end{tikzpicture}
Decoration Koch snowflake
This decoration replaces a straight line by a “line with a spike.” The Hausdorff dimension of Koch’s
snowflake’s is log 4/ log 3.
\begin{tikzpicture}[decoration=Koch snowflake]
\draw decorate{ (0,0) -- (3,0) };
\draw decorate{ decorate{ (0,-1) -- (3,-1) }};
\draw decorate{ decorate{ decorate{ (0,-2) -- (3,-2) }}};
\draw decorate{ decorate{ decorate{ decorate{ (0,-3) -- (3,-3) }}}};
\end{tikzpicture}
Decoration Cantor set
This decoration replaces a straight line by a “line with a gap in the middle.” The Hausdorff dimension
of the Cantor set is log 2/ log 3.
\begin{tikzpicture}[decoration=Cantor set,very thick]
\draw decorate{ (0,0) -- (3,0) };
\draw decorate{ decorate{ (0,-.5) -- (3,-.5) }};
\draw decorate{ decorate{ decorate{ (0,-1) -- (3,-1) }}};
\draw decorate{ decorate{ decorate{ decorate{ (0,-1.5) -- (3,-1.5) }}}};
\end{tikzpicture}
604
49
Entity-Relationship Diagram Drawing Library
Tik Z Library er
\usetikzlibrary{er} % LATEX and plain TEX
\usetikzlibrary[er] % ConTEXt
This packages provides styles for drawing entity-relationship diagrams.
This library is intended to help you in creating E/R-diagrams. It defines only few new styles, but using
the style entity instead of saying rectangle,draw makes the code more expressive.
49.1
Entities
The package defines a simple style for drawing entities:
(style, no value)
/tikz/entity
This style is to be used with nodes that represent entity types. It causes the node’s shape to be set to
a rectangle that is drawn and whose minimum size and width are set to sensible values.
Note that this style is called entity despite the fact that it is to be used for nodes representing entity
types (the difference between an entity and an entity type is the same as the difference between an object
and a class in object-oriented programming). If this bothers you, feel free to define a style entity type
instead.
Sheep
Genome
\begin{tikzpicture}
\node[entity] (sheep)
{Sheep};
\node[entity] (genome) [right=of sheep] {Genome};
\end{tikzpicture}
(style, no value)
/tikz/every entity
This style is evoked by the style entity. To change the appearance of entities, you can change this
style.
Sheep
Genome
\begin{tikzpicture}
[every entity/.style={draw=blue!50,fill=blue!20,thick}]
\node[entity] (sheep)
{Sheep};
\node[entity] (genome) [right=of sheep] {Genome};
\end{tikzpicture}
49.2
Relationships
Relationships are drawn using styles that are very similar to the styles for entities.
/tikz/relationship
(style, no value)
This style works like entity, only it is to be used for relationships. Again, relationships are actually
relationship types.
has
Sheep
Genome
\begin{tikzpicture}
\node[entity] (sheep) at (0,0)
{Sheep};
\node[entity] (genome) at (2,0)
{Genome};
\node[relationship]
at (1,1.5) {has}
edge (sheep)
edge (genome);
\end{tikzpicture}
605
(style, no value)
/tikz/every relationship
Works like every entity.
has
Sheep
49.3
Genome
\begin{tikzpicture}
[every entity/.style={fill=blue!20,draw=blue,thick},
every relationship/.style={fill=orange!20,draw=orange,thick,aspect=1.5}]
\node[entity] (sheep) at (0,0)
{Sheep};
\node[entity] (genome) at (2,0)
{Genome};
\node[relationship]
at (1,1.5) {has}
edge (sheep)
edge (genome);
\end{tikzpicture}
Attributes
(style, no value)
/tikz/attribute
This style is used to indicate that a node is an attribute. To connect an attribute to its entity, you can
use, for example, the child command or the pin option.
Sheep
name color
name
color
\begin{tikzpicture}
\node[entity] (sheep) {Sheep}
child {node[attribute] {name}}
child {node[attribute] {color}};
\end{tikzpicture}
\begin{tikzpicture}[every pin edge/.style=draw]
\node[entity,pin={[attribute]60:name},pin={[attribute]120:color}] {Sheep};
\end{tikzpicture}
Sheep
(style, no value)
/tikz/key attribute
This style is intended for key attributes. By default, the will cause the attribute to be typeset in italics.
Typically, underlining is used instead, but that looks ugly and it is difficult to implement in TEX.
(style, no value)
/tikz/every attribute
This style is used with every attribute, and therefore also for every key attribute.
\begin{tikzpicture}
[text depth=1pt,
every attribute/.style={fill=black!20,draw=black},
every entity/.style={fill=blue!20,draw=blue,thick},
every relationship/.style={fill=orange!20,draw=orange,thick,aspect=1.5}]
has
Sheep
name
Genome
\node[entity] (sheep) at (0,0)
{Sheep}
child {node [key attribute] {name}};
\node[entity] (genome) at (2,0)
{Genome};
\node[relationship]
at (1,1.5) {has}
edge (sheep)
edge (genome);
\end{tikzpicture}
606
50
Externalization Library
by Christian Feuersänger
Tik Z Library external
\usetikzlibrary{external} % LATEX and plain TEX
\usetikzlibrary[external] % ConTEXt
This library provides a high-level automatic or semi–automatic export feature for Tik Z pictures. Its
purpose is to convert each picture to a separate pdf without changing the document as such.
It also externalizes \label information (and other aux file related stuff) using auxiliary files.
50.1
Overview
There are several reasons why external images for at least some pictures are of interest:
1. Larger picture require a considerable amount of time, which is necessary for every compilation. However, only few images will change from run to run. It can simply save time to export finished images
and include them as final graphics.
2. It may be desirable to have final images for some graphics, for example to include them in third–party
programs or to communicate them electronically.
3. It may be necessary to typeset a file in environments where pgf and Tik Z are not available. In this
case, external images are the only way to ensure compatibility.
The purpose of this library is to provide a way to export any Tik Z-picture to separate pdf (or eps) images
without changing the main document. It is actually a simple user interface to the \beginpgfgraphicnamed
. . . \endpgfgraphicnamed framework of pgf which is discussed in section 106.
50.2
Requirements
For most users, the library does not need special attention since requirements are met anyway. It collects
all tokens between \begin{tikzpicture} and the next following \end{tikzpicture} and replaces them by
the appropriate graphics or it takes steps to generate such an image.
It can’t expand macros during this step, so the only requirement is that every picture’s end is directly
reachable from its beginning, without further macro expansion. Furthermore, the library assumes that all
LATEX pictures are ended with \end{tikzpicture}.
The library always searches for the next picture’s end, \end{tikzpicture}. As a consequence, you can’t
use nested pictures directly. You can nest pictures, but you have to avoid that the nested picture’s \end
command is found before the outer \end command (for example using bracing constructs or by writing the
nested picture into a separate macro call).
Consider using the \tikzexternaldisable method in case you’d like to skip selected pictures which do
not meet the requirements.
50.3
A Word About ConTEXt And Plain TEX
Currently, the basic layer backend \beginpgfgraphicnamed . . . \endpgfgraphicnamed relies on LATEX only,
so externalization is currently only supported for LATEX.
50.4
Externalizing Graphics
After loading the library, a call to \tikzexternalize is necessary to activate the externalization.
607
\documentclass{article}
% main document, called main.tex
\usepackage{tikz}
\usetikzlibrary{external}
\tikzexternalize % activate!
\begin{document}
\begin{tikzpicture}
\node {root}
child {node {left}}
child {node {right}
child {node {child}}
child {node {child}}
};
\end{tikzpicture}
A simple image is \tikz \fill (0,0) circle(5pt);.
\end{document}
The method works as follows: if the document is typeset normally, the library searches for replacement
images for every picture. Filenames are generated automatically in the default configuration. In our case,
the two file names will be main-figure0 and main-figure1. If they exist, those images are simply included
and the pictures as such are not processed. If graphics files do not exist, steps are taken to generate the
missing ones. Since (currently) only one output file can be set, each missing image needs to be generated by a
separate run of LATEX in which the \jobname is set to the desired image file name. In the default configuration
mode=convert with system call, these commands are issued automatically by using the \write18 method
to call system commands. It is also possible to output every required file name or to generate a makefile;
users will need to issue the required commands manually (or with make). The probably most comfortable
way is to use the default configuration with
pdflatex -shell-escape main
which authorizes pdflatex to call itself recursively to generate the images. When it finishes, all images are
generated and the document already includes them.
From this point on, successive runs of LATEX will use the final graphics files, the pictures won’t be used
anymore. Section 50.5 contains details about how to submit such a file to environments where pgf is not
available.
\tikzexternalize[hoptional argumentsi]
This command activates the externalization. It installs commands to replace every Tik Z-picture. It
needs to be called before \begin{document} because it may need to install its separate shipout routine.
The hoptional argumentsi can be any of the keys described below.
Note that the generation/modification of auxiliary files like .aux, .toc etc. is usually suppressed while
a single image is externalized (details for \label support follow).
It is also possible to write \tikzexternalize{hmain job namei} if the argument is delimited by curly
braces. This case is mainly for backwards compatibility and is no longer necessary. Since it might be
useful in rare circumstances, it is documented in section 50.4.5.
A detailed description about the process of externalization is provided in section 50.4.5.
\tikzexternalrealjob
After the library is loaded, this macro will always contain the correct main job’s name (in the
example above, it is main). It is to be used instead of \jobname when the externalization is in
effect.
\pgfactualjobname
Once \tikzexternalize has been called, \pgfactualjobname contains the name of the currently
generated output file (which may be main or main-figure0 or main-figure1 in our example above).
\jobname
The value of \jobname is one of \tikzexternalrealjob or \pgfactualjobname, depending
on the configuration. In short: if auxiliary file support (\label and \ref) is activated,
\jobname=\tikzexternalrealjob (since that’s the base file name of auxiliary files).
608
(no default)
/tikz/external/system call={htemplatei}
A template string used to generate system calls. Inside of {htemplatei}, the macro \image can be used
as placeholder for the image which is about to be generated while \texsource contains the main file
name (in truth, it contains \input{hmain file namei}, but that doesn’t matter).
The default depends on the value of \pgfsysdriver. For pgfsys-pdftex.def, it is
\tikzset{external/system call={pdflatex \tikzexternalcheckshellescape -halt-on-error
-interaction=batchmode -jobname "\image" "\texsource"}}
where \tikzexternalcheckshellescape inserts the value of the configuration key shell escape if
and only if the current document has been typeset with -shell-escape5 .
Other drivers result in slightly different calls. There is support for lualatex, xelatex, and dvips. The
precise values are written to the .log file as soon as you attempt to compile a document.
The argument {htemplatei} will be expanded using \edef, so any control sequences will be expanded.
During this evaluation, ‘\\’ will result in a normal backslash, ‘\’. Furthermore, double quotes ‘"’, single
quotes ‘’’, semicolons and dashes ‘-’ will be made to normal characters if any package uses them as
macros. This ensures compatibility with the german package, for example.
/tikz/external/shell escape={hcommand-line argi}
(no default, initially -shell-escape)
Contains the command line option for latex which enables the \write18 feature. For TEX-Live, this is
-shell-escape. For MikTEX, you should use \tikzexternalize[shell escape=-enable-write18].
50.4.1
Support for Labels and References In External Files
The external library comes with extra support for \label and \ref (and other commands which usually
store information in the .aux file) inside an external files.
There are, however, some points which need your attention when you try to use
a) \ref to something in the main document inside an externalized graphics or
b) \label in the externalized graphics which is referenced in the main document.
For point a), a \ref inside of an externalized graphics works only if you issue the required system
call manually or by make. The initial configuration mode=convert with system call does not support
\ref. But you can copy–paste the system call generated by mode=convert with system call and issue
it manually. The reason is that \ref information is stored in the main .aux file – but this auxiliary file is
not completely written when mode=convert with system call is invoked (there is a race condition). Note
that \pageref is not supported (sorry). Thus: if you have \ref inside of external graphics, consider using
mode=list and make or copy–paste the system call for the image(s) and issue it manually.
Point b) is implemented automatically by the external library. In detail, a \label inside of an externalized
graphics causes the external library to generate separate auxiliary files for every external image. These
files are called himagenamei.dpth. The extension .dpth indicates that the file also contains the image’s
depth (the baseline key of Tik Z). Furthermore, anything which would have been written to an .aux file
will be redirected to the .dpth file – but only things which occur inside of the externalized tikzpicture
environment. When the main document loads the image, it will copy the .dpth file into the main .aux
file. Then, successive compilations of the main document contain the external \label information. In other
words, a \label in an external graphics needs the following work flow:
1. The external graphics needs to be generated together with its .dpth (usually automatically by Tik Z).
2. The main document includes the external graphics and copies the .dpth content into its main .aux
file.
3. The main document needs to be translated once again to re-read its .aux file6 .
There is just one special case: if a \label/\ref combination is implemented itsself by a tikzpicture which
should be externalized, you need to proceed as for case a) since mode=convert with system call can’t
handle that stuff on its own. Thus, \label works automatically, just translate the main document often
enough.
5 Note that this is always true for the default configuration. This security consideration applies mainly for mode=list and
make which will also work without shell escapes.
6 Note that it is not possible to activate the content of an auxiliary file after \begin{document} in L
AT X.
E
609
(no default, initially true)
/tikz/external/aux in dpth={hbooleani}
Allows to disable the feature. Disabling it will safe one \newwrite command, i.e. a write register.
Also see the disable dependency files feature.
50.4.2
Customizing the Generated File Names
The default filename for externalized graphics is ‘hreal file namei-figure_hnumber i’ where hnumber i ranges
from 0 to whatever is required. However, there are a couple of ways to change the generated filenames:
• Changing the overall file name using a prefix,
• Changing the file name for a single figure using \tikzsetnextfilename,
• Changing the file name for a restricted set of figures using figure name.
/tikz/external/prefix={hfile name prefix i}
(no default, initially empty)
A shortcut for \tikzsetexternalprefix{hfile name prefix i}, see below.
\tikzsetexternalprefix{hfile name prefix i}
Assigns a common prefix used by all file names. For example,
\tikzsetexternalprefix{figures/}
will prepend figures/ to every external graphics file name.
Please note that \tikzsetexternalprefix is the only way to assign a prefix in case you want to prepare
your document for environments where pgf is not installed (see section 50.5).
\tikzsetnextfilename{hfile namei}
Sets the file name for the next Tik Z picture or \tikz short command. It will only be used for the next
picture.
Pictures for which no explicit file name has been set (or the next file name is empty) will get automatically
generated file names.
Please note that prefix will still be prepended to {hfile namei}.
\documentclass{article}
% main document, called main.tex
\usepackage{tikz}
\usetikzlibrary{external}
\tikzexternalize[prefix=figures/] % activate
\begin{document}
\tikzsetnextfilename{trees}
\begin{tikzpicture} % will be written to ’figures/trees.pdf’
\node {root}
child {node {left}}
child {node {right}
child {node {child}}
child {node {child}}
};
\end{tikzpicture}
\tikzsetnextfilename{simple}
A simple image is \tikz \fill (0,0) circle(5pt);. % will be written to ’figures/simple.pdf’
\begin{tikzpicture} % will be written to ’figures/main-figure0.pdf’
\draw[help lines] (0,0) grid (5,5);
\end{tikzpicture}
\end{document}
pdflatex -shell-escape main
610
(no default)
/tikz/external/figure name={hnamei}
Same as \tikzsetfigurename{hnamei}.
\tikzsetfigurename{hnamei}
Changes the names of all following figures. It is possible to change figure name during the document
either using \tikzset{external/figure name={hnamei}} or with this command. A unique counter
will be used for each different {hnamei}, and each counter will start at 0.
The value of prefix will be applied after figure name has been evaluated.
\documentclass{article}
% main document, called main.tex
\usepackage{tikz}
\usetikzlibrary{external}
\tikzexternalize % activate
\begin{document}
\begin{tikzpicture} % will be written to ’main-figure0.pdf’
\node {root}
child {node {left}}
child {node {right}
child {node {child}}
child {node {child}}
};
\end{tikzpicture}
{
\tikzsetfigurename{subset_}
A simple image is \tikz \fill (0,0) circle(5pt);. % will be written to ’subset_0.pdf’
\begin{tikzpicture} % will be written to ’subset_1.pdf’
\draw[help lines] (0,0) grid (5,5);
\end{tikzpicture}
}% here, the old file name will be restored:
\begin{tikzpicture} % will be written to ’main-figure1.pdf’
\draw (0,0) -- (5,5);
\end{tikzpicture}
\end{document}
The scope of figure name ends with the next closing brace.
Remark: Use \tikzset{external/figure name/.add={prefix_}{_suffix_}} to add a prefix_ and
a _suffix_ to the actual value of figure name.
\tikzappendtofigurename{hsuffix i}
Appends hsuffix i to the actual value of figure name.
It is a shortcut for \tikzset{external/figure name/.add={}{hsuffix i}} (a shortcut which is also
supported if Tik Z is not installed, see below).
50.4.3
Remaking Figures or Skipping Figures
\tikzpicturedependsonfile{hfile namei}
Adds a dependency for the next picture which is about to be externalized. If the command is invoked
within a picture environment, it adds a dependency for the surrounding picture. Dependencies are
written into htarget filei.dep in the format
htarget filei.\tikzexternalimgextension:
hfile namei.
The effect is that if hfile namei changes, the external graphics associated with the picture shall be
remade.
This command uses the contents of \tikzexternalimgextension to check for graphics. If you encounter
difficulties with image extensions, consider redefining this macro (after \tikzexternalize).
Limitations: this command is currently only supported for mode=list and make and the generated
makefile.
611
\tikzexternalfiledependsonfile{hexternal graphicsi}{hfile namei}
A variant of \tikzpicturedependsonfile which adds a dependency for an hexternal graphicsi. The
argument hexternal graphicsi must be the path as it would have been generated by the external library,
i.e. without file extension but including any prefixes.
(no value)
/tikz/external/disable dependency files
Allows to (irreversibly) disable the generation of file dependencies. Disabling it will safe one \newwrite
command, i.e. a write register. Note that the write register is only allocated if the feature has been used
at all. This key needs to be provided as argument to \tikzexternalize (or it needs to be set before
calling \tikzexternalize).
Also see the aux in dpth key.
(default true)
/tikz/external/force remake={hbooleani}
A boolean which is used to customize the up-to-date checks of all following figures. Every up-to-date
check will fail, resulting in automatic regeneration of every following figure.
\tikzset{external/force remake}
\begin{tikzpicture}
\draw (0,0) circle(5pt);
\end{tikzpicture}
You can also use force remake inside of a local TEX group to remake only selected pictures. The
example
\tikz \draw (0,0) -- (1,1);
{
\tikzset{external/force remake}
\begin{tikzpicture}
\draw (0,0) circle(5pt);
\end{tikzpicture}
}
\tikz \draw (0,0) -- (1,1);
will only apply force remake to the second figure.
Up-to-date checks are applied for mode=convert with system call and the makefile generated by
mode=list and make.
(default true)
/tikz/external/remake next={hbooleani}
A variant of force remake which applies only to the next image.
(default true)
/tikz/external/export next={hbooleani}
A boolean which can be used to disable the export mechanism for single pictures.
(no default, initially true)
/tikz/external/export={hbooleani}
A boolean which can be used to disable the export mechanism for all pictures inside of the current
TEX-scope.
\begin{document}
\begin{tikzpicture} % will be exported
...
\end{tikzpicture}
{
\tikzset{external/export=false}
\begin{tikzpicture} % won’t be exported
...
\end{tikzpicture}
...
}
\begin{tikzpicture} % will be exported
...
\end{tikzpicture}
\end{document}
612
For LATEX, the feature lasts until the next \end{h·i} (this holds for every call to \tikzset).
(no default, initially md5)
/tikz/external/up to date check={hchoicei}
The external lib has to decide when some existing figure is up-to-date. In such a case, it can be used
without remaking it. Outdated pictures will be remade.
The key up to date check allows to choose among a couple of heuristics which are supposed to catch
the most important reasons to remake a figure.
The up to date check can be overrule by any of the force remake or remake next keys: if one of
them is true, the figure is not up-to-date.
The choice simple is based on the existence of the file: the file is up-to-date if and only if it exists.
The choice md5 generates an MD5 checksum of the picture for which the up-to-date check is running.
The MD5 is compared against the MD5 of the previous run, which, in turn, will be written into an extra
file with the extension .md5. This file will be modified if and only if the MD5 comparison indicates a
difference. The MD5 computation is based on the pdfTEX method \pdfmdfivesum. If it is unavailable
for some reason, the choice diff will be used instead.
The choice diff is the same as MD5 – except that it compares the picture content as-is instead of a hash.
The .md5 file will be used to compare an old version with the current one – but its content is some
“normalized” version of the picture for internal use.
Attention: the content–based strategies md5 and diff operate on the picture content – and only on
the picture content. Here, “picture content” only includes the top–level tokens; no expansion is applied
and no included files are part of the strategies. If you change preamble styles, you have to rebuild
the figures manually (for example by deleting the generated graphics files). If you have include files,
consider using \tikzpicturedependsonfile and its variants. Since this key provides heuristics, you
should always remake your figures before you finally publish your document. Example: Suppose we
have the following picture which depends on a command \mycommand:
\def\mycommand{My comment}
\begin{tikzpicture}
\node at (0,0) {\mycommand};
\end{tikzpicture}
What happens if you change “My comment” to “My super comment”? Well, external will not pick it up;
you will need to handle this manually. However, if you modify anything between \begin{tikzpicture}
and \end{tikzpicture}, the external library will pick it up and regenerate the picture.
The up to date check is applied for mode=convert with system call and mode=list and make.
\tikzexternaldisable
Allows to disable the complete externalization. While export next will still collect the contents of
picture environments, this command uninstalls the hooks for the external library completely. Thus,
nested picture environments or environments where \end{tikzpicture} is not directly reachable won’t
produce compilation failures – although it is not possible to externalize them automatically.
The externalization remains disabled until the end of the next TEX group (or environment) or until the
next call to \tikzexternalenable.
\tikzexternalenable
Re-enables a previously running externalization after \tikzexternaldisable.
50.4.4
Customizing the Externalization
(no default, initially true)
/tikz/external/figure list={hbooleani}
A boolean which configures whether a figure list shall be generated. A figure list is an output file named
{hjobnamei}.figlist which is filled with file names of each figure, one per line.
This file is not used by TEX anymore, its purpose is to issue the required conversion commands pdflatex
-jobname {hpicture file namei} {hmain filei} manually (or in a script). See section 50.4.5 for the details
about the expected system call (or activate mode=convert with system call and inspect your log file).
613
\documentclass{article}
% main document, called main.tex
\usepackage{tikz}
\usetikzlibrary{external}
\tikzexternalize[
mode=graphics if exists,
figure list=true,
prefix=figures/]
\begin{document}
\tikzsetnextfilename{trees}
\begin{tikzpicture}
\node {root}
child {node {left}}
child {node {right}
child {node {child}}
child {node {child}}
};
\end{tikzpicture}
\tikzsetnextfilename{simple}
A simple image is \tikz \fill (0,0) circle(5pt);.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (5,5);
\end{tikzpicture}
\end{document}
pdflatex main
generates main.figlist containing
figures/trees
figures/simple
figures/main-figure0
(no default, initially convert with system call)
/tikz/external/mode={hchoicei}
Configures what to do with Tik Z pictures (unless we are currently externalizing one particular image,
in that case, these modes are ignored).
The preconfigured mode convert with system call checks whether external graphics files are upto-date and includes them if that is the case. Any picture which is not up-to-date will be generated
automatically using a system call. The system call can be configured using the system call template.
The up-to-date check is applied according to the up to date check key. As soon as convert with
system call is set, the figure list will be disabled – such a file is not required. In case you still need
or want it, you can enable it after setting mode.
Please note that system calls may be disabled for security reasons. For pdflatex, they can be enabled
using
pdflatex -shell-escape
while other TEX variants may need other switches. The feature is sometimes called \write18.
The choice only graphics always tries to replace pictures with external graphics. It is an error if the
graphics file does not exist.
The choice no graphics (or, equivalently, only pictures) typesets Tik Z pictures without checking for
external graphics.
A mixture is graphics if exists, it checks whether a suitable graphics file exists and includes it if
that is the case. If it does not exist, the picture is typeset using TEX.
Mode list only skips every Tik Z picture; it only generates the file {hmain filei}.figlist containing
file names for every picture, the contents of any picture environment is thrown away and a replacement
text is shown. This implies figure list=true. See also the list and make mode which includes
available graphics.
614
The mode list and make is similar to list only: it generates the same file {hmain filei}.figlist,
but any images which exist already are included as graphics instead of ignoring them. Furthermore,
this mode generates an additional file: {hmain filei}.makefile. This allows to use a work flow like
% step 1: generate main.makefile:
pdflatex main
% step 2: generate ALL graphics on 2 processors:
make -j 2 -f main.makefile
% step 3: include the graphics:
pdflatex main
This last make method is optional: list and make just assumes that images are generated somehow (not necessarily with the generated makefile). The generated makefile allows parallel externalization of graphics on multi-core systems and it supports any file dependencies configured with
\tikzpicturedependsonfile. Furthermore, it respects the force remake and remake next keys.
(no default, initially true)
/tikz/external/verbose IO={hbooleani}
A boolean which configures whether I/O operations shall be listed in the logfile.
(no default, initially true)
/tikz/external/verbose optimize={hbooleani}
A boolean which configures whether optimization operations shall be listed in the logfile.
(no default, initially true)
/tikz/external/verbose={hbooleani}
Sets all verbosity flags to hbooleani.
(no default, initially true)
/tikz/external/optimize={hbooleani}
Configures whether the conversion process shall be optimized. This affects only the case when \jobname
differs from the main file name, i.e. when single pictures are converted.
In that case, the main file is compiled as usual - but everything except the selected picture is thrown
away. If optimization is enabled, all other pictures won’t be processed at all. Furthermore, expensive
commands which do not contribute to the selected picture will be thrown away as well.
The default implementation discards \includegraphics commands which are not inside of the selected
picture to reduce conversion time.
It is possible to add commands which shall be optimized away, see below.
/tikz/external/optimize command away=h\command i{hrequired argument counti}
(no default)
Installs commands to optimize h\command i away. As is described above, optimization applies to the
case when single pictures are converted: one usually doesn’t need to process (probably expensive)
commands which do not contribute to the selected picture.
The argument {hrequired argument counti} is either empty or a non-negative integer between 0 and 9.
It denotes the number of arguments which should be consumed after h\command i. In any case, one
argument in square brackets after the command will be recognized as well. To be more precise, the
following cases for arguments of h\command i are supported:
1. If {hrequired argument counti} is empty (the default), h\command i may take one optional argument
in square brackets and one in curly braces (which is also optional).
2. If {hrequired argument counti} is not empty, {h\command i} may take one optional argument in
square brackets. Furthermore, it expects exactly {hrequired argument counti} following arguments.
Example:
\tikzset{external/optimize command away=\includegraphics}
\newcommand{\myExpensiveMacro}[1]{Very expensive!}
\tikzset{external/optimize command away=\myExpensiveMacro}
\newcommand{\myExpensiveMacroWithThreeArgs}[3]{Very expensive!}
\tikzset{external/optimize command away={\myExpensiveMacroWithThreeArgs}{3}}
615
% A command with optional argument:
\newcommand{\aFurtherExample}[3][]{Very expensive!}
% consume only two arguments: the first optional one will be processed
% anyway:
\tikzset{external/optimize command away={\myExpensiveMacroWithThreeArgs}{2}}
The argument h\command i must be the name of a single macro. Any occurrence of this macro, together
with its arguments, will be removed.
\begin{tikzpicture}
% this picture is currently converted!
\end{tikzpicture}
This here is outside of the converted picture and contains \myExpensiveMacro. It will be discarded.
This call: \myExpensiveMacro[argument=value]{Argument} as well.
And this here: \myExpensiveMacro{Argument} also.
The default is to optimize \includegraphics away.
This key is actually a style which sets the optimize/install and optimize/restore keys.
(no value)
/tikz/external/optimize/install
A command key which contains code to install optimizations. You can append code here (or clear the
macro) if you need to modify the optimization.
(no value)
/tikz/external/optimize/restore
A command key which contains code to undo optimizations. You can append code here (or clear the
macro) if you need to modify the optimization.
(no default, initially false)
/tikz/external/only named={hbooleani}
If enabled, only pictures for which file names have been set explicitly using \tikzsetnextfilename will
be considered, no file names will be generated automatically.
(initially \pgfimage{#1})
/pgf/images/include external
This command key constitutes the public interface to exchange the \includegraphics command used
for the image inclusion. If can be overwritten using include external/.code={hTEX codei}.
Its description can be found in the corresponding basic layer documentation on page 1069.
Just one example here: you can use
\pgfkeys{/pgf/images/include external/.code={\includegraphics[viewport=0 0 211.28 175.686]{#1}}}
to manually change the viewport (bounding box) for included graphics.
Another example (of probably limited use) is
\pgfkeys{/pgf/images/include external/.code={\href{file:#1}{\pgfimage{#1}}}}
which will generate a clickable hyperlink around the image. Clicking on it opens the single exported
file7 .
If you want to limit the effects of this key to just one externalized figure, use
{
\pgfkeys{/pgf/images/include external/.code={\includegraphics[viewport=0 0 211.28 175.686]{#1}}}
\begin{tikzpicture}
...
\end{tikzpicture}
}% this brace ends the effect of ‘include external’
\tikzifexternalizing{htrue codei}{hfalse codei}
This command can be used to check whether an image is currently written to its separate graphics file
(if the “grab” procedure is running). If so, the {htrue codei} will be executed. If not, that means if the
main document is being typeset normally, the {hfalse codei} will be invoked.
This command must be used after \tikzexternalize.
7 This
requires all external graphics files in the same base directory as the main .pdf file.
616
\tikzifexternalizingnext{htrue codei}{hfalse codei}
Like \tikzifexternalizing, but this variant also checks if the next following figure is the one which
is about to be written to its separate graphics file.
50.4.5
Details About The Process
The standard run pdflatex hmain documenti causes the external library to check every occurrence of \begin{tikzpicture} and every \tikz shortcommand. If it finds a picture which shall be exported, it queries
the respective file name and checks whether the file exists already. If so, it includes the external graphics. If
not, it requires an externalization which can be done automatically (the default), semi–automatically (with
mode=list and make) or manually (by issuing the requires system calls somehow).
The library can detect whether it runs in “conversion mode”, i.e. if it should only process a single image.
To do so, it checks whether the internal macro \tikzexternalrealjob exists. If so, its contents is assumed
to be hmain documenti (without the suffix .tex). Usually, this macro is set by the conversion system call,
pdflatex -jobname "main-figure0" "\def\tikzexternalrealjob{main}\input{main}"
where main-figure0 is the picture we are currently externalizing and main.tex is the main document.
As soon as “conversion mode” has been detected, pgf changes the output routine. The complete file
main.tex is processed as normal, but only the part of the desired picture will be written to the output file, in
our case main-figure0.pdf. The rest of the document is silently thrown away. Of course, such a conversion
process is quite expensive since we need to do it for every picture. Since everything except the current
picture is thrown away, the library skips all other pictures. Furthermore, any \includegraphics commands
which are outside of the converted Tik Z-picture will be skipped as well. Thus, the conversion process should
be much faster than typesetting the complete document, but it still requires its time. Eventually, the call
\input{main} returns and the picture is ready. From this point on, the external graphics will be used.
There is another possibility to communicate hmain documenti to the subprocess performing the externalization: namely to write ‘\tikzexternalize{main}’ into the document. In this case, the conversion system
call will be
pdflatex -jobname "main-figure0" "main"
and the contents of \tikzexternalrealjob is set automatically. This case is detected by \tikzexternalize,
and the system call is updated automatically (by patching its \texsource template argument). It is not
necessary to change the system call manually.
The sequence in which system calls are performed and the decision whether they are issued automatically
is governed by the mode key, consult its documentation for details.
50.5
Using External Graphics Without pgf Installed
Given that every picture has been exported correctly, one may want to compile a file without pgf and
Tik Z installed. Tik Z comes with a minimal package which contains just enough commands to replace every
tikzpicture environment and the \tikz short command with the appropriate external graphics. It can be
found at
latex/pgf/utilities/tikzexternal.sty
and needs to be used instead of \usepackage{tikz}. So, we uncomment \usepackage{tikz} and our
example from the beginning becomes
617
\documentclass{article}
% main document, called main.tex
%\usepackage{tikz}
\usepackage{graphicx}
\usepackage{tikzexternal}
%\usetikzlibrary{external}
\tikzexternalize
\begin{document}
\begin{tikzpicture}
\node {root}
child {node {left}}
child {node {right}
child {node {child}}
child {node {child}}
};
\end{tikzpicture}
A simple image is \tikz \fill (0,0) circle(5pt);.
Furthermore, we might want to draw \tikz[baseline]\draw (0,-1) rectangle (1,1);
\end{document}
where the following files are necessary to compile the document:
tikzexternal.sty
main.tex
main-figure0.pdf
main-figure1.pdf
main-figure2.pdf
If there are any ‘.dpth’ files, for example main-figure2.dpth, these files are also required. They contain
information for the Tik Z baseline option (or \labels inside external graphics).
Just copy the .sty file into the directory of your main.tex file and use it as part of your document.
Please keep in mind, that only tikzpicture environments and \tikz short images are available within the
externalization framework. Additionally, calls to \tikzset and \pgfkeys won’t lead to compilation errors because they are simply ignored. But since pgfkeys is not available, any option supplied to \tikzexternalize
is ignored.
Attention: Since the simple replacement \usepackage{tikzexternal} doesn’t support the key–value
interface, you need to use \tikzsetexternalprefix instead of the prefix option and \tikzsetfigurename
instead of the figure name option since \tikzset is not available in such a context.
Remark: Some of the features of this library are mainly useful to improve the speed of successive document
compilations. In other words: you can’t use all features in this context, keep it simple.
50.6
eps Graphics Export
It is also possible to use eps graphics instead of pdf files. There are different ways to produce them, for
example to use pdflatex and call pdftops -eps {hpdf filei} {heps filei} afterwards. You could add this
command to the system call option.
Alternatively, you can use latex and dvips for image conversion as is explained for the system call
option, see page 609. See the documentation for the basic level externalization in section 106 for restrictions
of other drivers.
50.7
Bitmap Graphics Export
Occasionally, you may have an extremely large graphics which takes long times to render. It might be
interesting to generate a bitmap (raster) image, which displays much faster (for example in a presentation).
I have used this feature to speed-up the display of large shadings.
The external library can be customized to export bitmap images – with the help of external programs.
Due to the dependence of external programs, you may need to adjust these commands manually. For
example, on my computer, the ImageMagick Suite is installed which comes with the convert tool. Together
with pdflatex, I can define the following style:
618
\tikzset{
% Defines a custom style which generates BOTH, .pdf and .png export
% but prefers the .png on inclusion.
%
% This style is not pre-defined, you may need to copy-paste and
% adjust it.
png export/.style={
external/system call/.add=
{}
{; convert -density 300 -transparent white "\image.pdf" "\image.png"},
%
/pgf/images/external info,
/pgf/images/include external/.code={%
\includegraphics
[width=\pgfexternalwidth,height=\pgfexternalheight]
{##1.png}%
},
}
}
The example above defines a new style called ‘png export’ which, when it is set with \tikzset{png export}
somewhere in the document, modifies the configuration for both file generation and file input. The file
generation is modified by appending the ImageMagick command to system call (separated by ‘;’ as usual
on Linux). This is, in principle, enough to generate a .png file. The include external command is
overwritten such that it uses the .png file instead of the .pdf file (which exists as well in the configuration
above). But since a .png file can have a much higher resolution than the desired image dimensions, we have
to add width and height explicitly. Usually, the external library does not provide size information (it
is unnecessary for .pdf or .eps since these formats have their bounding box information). To enable size
information, the style uses the external info key, which, in turn, provides the \pgfexternalwidth and
\pgfexternalheight commands.
Now we can use \tikzset{png export} either document-wide or just for one particular image. The
configuration remains in effect until the end of the current environment (or until the next closing curly brace
‘}’).
(no default, initially false)
/pgf/images/external info={hbooleani}
If this key is activated, the size for any externalized image will be stored explicitly into the associated
.dpth file.
When the file is included by \pgfincludeexternalgraphics (or automatically by the external library), the width is available as \pgfexternalwidth and the height as \pgfexternalheight.
50.8
50.8.1
Compatibility Issues
References In External Pictures
It is allowed if a picture contains references, for example \tikz \node {Reference to \ref{a:label}};.
There is just one issue: if the main job is currently compiling, its .aux file is not in its final state (even
worse: it may not be readable at all). The picture externalization, however, needs the main .aux file to
query any references.
Thus, you will need to invoke pdflatex -jobname himagei hmainfilei manually for any image which
contains references.
This problem arises only for mode=convert with system call. In this case, the external library
creates a special \jobname.auxlock file to check whether the main .aux file is currently usable.
50.8.2
Compatibility With Other Libraries or Packages
The external library has the following compatibility issues:
1. The external library comes with special support for \usetikzlibrary{fadings}: the fadings library
may define local pictures which would be externalized (although they shouldn’t). There is special
handling to suppress this bug if \tikzexternalize is called after \usetikzlibrary{fadings} or if
all fadings are defined before \tikzexternalize.
2. Problems have been reported when using \tikzexternalize (or the basic layer externalization) together with \usepackage{glossary}. This problem disappears if \tikzexternalize is called before
\usepackage{glossary}.
619
3. Problems with \usepackage{pdfpages} and \usepackage{vmargin}: The external library replaces
the current shipout routine of TEX during its externalization. This might raise problems with other
packages which also manipulate the shipout routine (like the mentioned ones).
To fix those problems, use
\usetikzlibrary{external}
\tikzifexternalizing{%
% don’t include package XYZ here
}{%
\usepackage{pdfpages}
\usepackage{vmargin}
...
}%
This uses the requested packages for the main document, but not for the single, exported graphics.
In general, the \tikzifexternalizing feature might be used to solve package conflicts and the
\tikzexternaldisable and \tikzexternalenable features can be used to solve problems with single pictures.
50.8.3
Compatibility With Bounding Box Restrictions
Bounding box restrictions provide no problem when used with eps graphics. However, they pose problems
for pdflatex, so you may need to use the latex / dvips combination if you use bounding box restrictions
and externalization. Currently, the only possibility for bounding box restrictions and pdflatex is to use a
combination of trim left / trim right / baseline: these keys do not really truncate the bounding box,
they only store horizontal and vertical shifts (also see the trim lowlevel key in this context).
50.8.4
Interoperability With The Basic Layer Externalization
This library is fully compatible with \beginpgfgraphicnamed. . . \endpgfgraphicnamed environments. However, you will need to use the export next=false key to avoid conflicts:
\beginpgfgraphicnamed{picture4}
\tikzset{external/export next=false}
\begin{tikzpicture}
\draw (0,0) -- (4,4);
\end{tikzpicture}
\endpgfgraphicnamed
Please keep in mind that file prefixes do not apply to the basic layer.
620
51
Fading Library
Tik Z Library fadings
\usepgflibrary{fadings}
\usepgflibrary[fadings]
\usetikzlibrary{fadings}
\usetikzlibrary[fadings]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
The package defines a number of fadings, see Section 23 for an introduction. The Tik Z version defines
special Tik Z commands for creating fadings. These commands are explained in Section 23.
Fading name
Example (solid blue faded on checkerboard)
west
east
north
south
circle with fuzzy edge 10 percent
circle with fuzzy edge 15 percent
circle with fuzzy edge 20 percent
fuzzy ring 15 percent
621
52
Fitting Library
Tik Z Library fit
\usetikzlibrary{fit} % LATEX and plain TEX
\usetikzlibrary[fit] % ConTEXt
The library defines (currently only two) options for fitting a node so that it contains a set of coordinates.
When you load this library, the following options become available:
/tikz/fit=hcoordinates or nodesi
(no default)
This option must be given to a node path command. The hcoordinates or nodesi should be a sequence
of Tik Z coordinates or node names, one directly after the other without commas (like with the plot
coordinates path operation). Examples are (1,0) (2,2) or (a) (1,0) (b), where a and b are nodes.
For this sequence of coordinates, a minimal bounding box is computed that encompasses all the listed
hcoordinates or nodesi. For coordinates in the list, the bounding box is guaranteed to contain this
coordinate, for nodes it is guaranteed to contain the east, west, north and south anchors of the node.
In principle (the details will be explained in a moment), things are now set up such that the text box
of the node will be exactly this bounding box.
Here is an example: We fit several points in a rectangular node. By setting the inner sep to zero, we
see exactly the text box of the node. Then we fit these points again in a circular node. Note how the
circle encompasses exactly the same bounding box.
box
\begin{tikzpicture}[inner sep=0pt,thick,
dot/.style={fill=blue,circle,minimum size=3pt}]
\draw[help lines] (0,0) grid (3,2);
\node[dot] (a) at (1,1) {};
\node[dot] (b) at (2,2) {};
\node[dot] (c) at (1,2) {};
\node[dot] (d) at (1.25,0.25) {};
\node[dot] (e) at (1.75,1.5) {};
\node[draw=red,
fit=(a) (b) (c) (d) (e)] {box};
\node[draw,circle,fit=(a) (b) (c) (d) (e)] {};
\end{tikzpicture}
Every time the fit option is used, the following style is also applied to the node:
(style, initially empty)
/tikz/every fit
Set this style to change the appearance of a node that uses the fit option.
The exact effects of the fit option are the following:
1. A minimal bounding box containing all coordinates is computed. Note that if a coordinate like (a)
is used that contains a node name, this has the same effect as explicitly providing the (a.north)
and (a.south) and (a.west) and (a.east). If you wish to refer only to the center of the a node,
use (a.center) instead.
2. The text width option is set to the width of this bounding box.
3. The align=center option is set.
4. The anchor is set to center.
5. The at position of the node is set to the center of the computed bounding box.
6. After the node has been typeset, its height and depth are adjusted such that they add up to the
height of the computed bounding box and such that the text of the node is vertically centered
inside the box.
The above means that, generally speaking, if the node contains text like box in the above example, it
will be centered inside the box. It will be difficult to put the text elsewhere, in particular, changing the
anchor of the node will not have the desired effect. Instead, what you should do is to create a node
with the fit option that does not contain any text, give it a name, and then use normal nodes to add
text at the desired positions. Alternatively, consider using the label or pin options.
Suppose, for instance, that in the above example we want the word “box” to appear inside the box, but
at its top. This can be achieved as follows:
622
box
\begin{tikzpicture}[inner sep=0pt,thick,
dot/.style={fill=blue,circle,minimum size=3pt}]
\draw[help lines] (0,0) grid (3,2);
\node[dot] (a) at (1,1) {};
\node[dot] (b) at (2,2) {};
\node[dot] (c) at (1,2) {};
\node[dot] (d) at (1.25,0.25) {};
\node[dot] (e) at (1.75,1.5) {};
\node[draw=red,fit=(a) (b) (c) (d) (e)] (fit) {};
\node[below] at (fit.north) {box};
\end{tikzpicture}
Here is a real-life example that uses fitting:
ρ
F (b,R)
F (c,R)
a
b
d
c
f
e
\begin{tikzpicture}
[vertex/.style={minimum size=2pt,fill,draw,circle},
open/.style={fill=none},
sibling distance=1.5cm,level distance=.75cm,
every fit/.style={ellipse,draw,inner sep=-2pt},
leaf/.style={label={[name=#1]below:$#1$}},auto]
\node [vertex] (root) {}
child { node [vertex,open] {}
child { node [vertex,open] {}
child { node [vertex] (b’s parent) {}
child { node [vertex] {}
child { node [vertex,leaf=d] {} }
child { node [vertex,leaf=e] {} } }
child { node [vertex,leaf=b] {} } }
child { node [vertex,leaf=a] {} } }
child { node [coordinate] {}
child[missing]
child { node [vertex] (f’s parent) {}
child { node [vertex,leaf=c] {} }
child { node [vertex,leaf=f] {} } } }
edge from parent node {$\rho$} };
\node [fit=(d) (e) (b) (b’s parent),label=above left:$F^{(b,R)}$] {};
\node [fit=(c) (f) (f’s parent),label=above right:$F^{(c,R)}$]
{};
\end{tikzpicture}
(no default, initially 0)
/tikz/rotate fit=hanglei
This key fits hcoordinates or nodesi inside a node that is rotated by hanglei. As a side effect, it also sets
the /tikz/rotate key.
623
\begin{tikzpicture}[inner sep=0pt,thick,
dot/.style={fill=blue,circle,minimum size=3pt}]
\draw[help lines] (0,0) grid (3,2);
\node[dot] (a) at (1,1) {};
\node[dot] (b) at (2,2) {};
\node[dot] (c) at (1,2) {};
\node[dot] (d) at (1.25,0.25) {};
\node[dot] (e) at (1.75,1.5) {};
\node[draw, fit=(a) (b) (c) (d) (e)] {};
\node[draw=red, rotate fit=30, fit=(a) (b) (c) (d) (e)] {};
\end{tikzpicture}
624
53
Fixed Point Arithmetic Library
Tik Z Library fixedpointarithmetic
\usepgflibrary{fixedpointarithmetic}
\usepgflibrary[fixedpointarithmetic]
\usetikzlibrary{fixedpointarithmetic}
\usetikzlibrary[fixedpointarithmetic]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library provides an interface to the LATEX package fp for fixed point arithmetic. In addition to
loading this library you must ensure fp is loaded, otherwise errors will occur.
53.1
Overview
Whilst the mathematical engine that comes with pgf is reasonably fast and flexible when it comes to parsing,
the accuracy tends to be fairly low, particularly for expressions involving many operations chained together.
In addition the range of values that can be computed is very small: ±16383.99999. Conversely, the fp package
has a reasonably high accuracy, and can perform computations over a wide range of values (approximately
±9.999 × 1017 ), but is comparatively slow and not very flexible, particularly regarding parsing.
This library enables the combination of the two: the flexible parser of the pgf mathematical engine with
the evaluation accuracy of fp. There are, however, a number of important points to bear in mind:
• Whilst fp supports very large numbers, pgf and Tik Z do not. It is possible to calculate the result of
2^20 or 1.2e10+3.4e10, but it is not possible to use these results in pictures directly without some
“extra work”.
• The pgf mathematical engine will still be used to evaluate lengths, such as 10pt or 3em, so it is not
possible for an length to exceed the range of values supported by TEX-dimensions (±16383.99999pt),
even though the resulting expression is within the range of fp. So, for example, one can calculate
3cm*10000, but not 3*10000cm.
• Not all of the functions listed in Section 89, have been mapped onto fp equivalents. Of those that have
been, it is not guaranteed that functions will perform in the same way as they do in pgf. Reference
should be made to the documentation for fp.
• In pgf, trigonometric functions such as sin and cos assume arguments are in degrees, and functions
such as asin and acos return results in degrees. Although fp uses radians for such functions, pgf
automatically converts arguments from degrees to radians, and converts results from radians to degrees,
to ensure everything “works properly”.
• The overall speed will actually be slower than using pgf mathematical engine. The calculating power
of fp comes at the cost of an increased processing time.
53.2
Using Fixed Point Arithmetic in PGF and Tik Z
The following key is provided to use fp in pgf and Tik Z:
(no default)
/pgf/fixed point arithmetic=hoptionsi
alias /tikz/fixed point arithmetic
This key will set the key path to /pgf/fixed point, and execute hoptionsi. Then it will install the
necessary commands so that the pgf parser will use fp to perform calculations. The best way to use
this key is as an argument to a scope or picture. This means that fp does not always have to be used,
and pgf can use its own mathematical engine at other times, which can lead to a significant reduction
in the time for a document to compile.
Currently there are only a few keys key supported for hoptionsi:
/pgf/fixed point/scale results=hfactor i
(no default)
As noted above, fp can process a far greater range of numbers than pgf and Tik Z. In order to use
results from fp in a {pgfpicture} or a {tikzpicture} they need to be scaled. When this key is used
pgf will scale results of any evaluation by hfactor i. However, as it is not desirable for every part of
every expression to be scaled, scaling will only take place if a special prefix * is used. If * is used at
625
the beginning of an expression the evaluation of the expression will evaluated and then multiplied by
hfactor i.
\begin{tikzpicture}[fixed point arithmetic={scale results=10^-6}]
\draw [help lines] grid (3,2);
\draw (0,0) -- (2,2);
\draw [red, line width=4pt] (*1.0e6,0) -- (*3.0e6,*2.0e6);
\end{tikzpicture}
A special case of scaling involves plots of data containing large numbers from files. It is possible
to “pre-process” a file, typically using the application that generates the data, to either precede the
relevant column with * or to perform the scaling as part of the calculation process. However, it may
be desirable for the data in a plot to appear in a table as well, so, two files would be required, one
pre-processed for plotting, and one not. This extra work may be undesirable so the following keys are
provided:
/pgf/fixed point/scale file plot x=hfactor i
(no default)
This key will scale the first column of data read from a file before it is plotted. It is independent
of the scale results key.
/pgf/fixed point/scale file plot y=hfactor i
(no default)
This key will scale the second column of data read from a file before it is plotted.
/pgf/fixed point/scale file plot z=hfactor i
This key will scale the third column of data read from a file before it is plotted.
626
(no default)
54
Floating Point Unit Library
by Christian Feuersänger
Tik Z Library fpu
\usepgflibrary{fpu}
\usepgflibrary[fpu]
\usetikzlibrary{fpu}
\usetikzlibrary[fpu]
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
The floating point unit (fpu) allows the full data range of scientific computing for use in pgf. Its core
is the pgf math routines for mantissa operations, leading to a reasonable trade–of between speed and
accuracy. It does not require any third–party packages or external programs.
54.1
%
%
%
%
Overview
The fpu provides a replacement set of math commands which can be installed in isolated placed to achieve
large data ranges at reasonable accuracy. It provides at least8 the IEEE double precision data range,
−1 · 10324 , . . . , 1 · 10324 . The absolute smallest number bigger than zero is 1 · 10−324 . The FPU’s relative
precision is at least 1 · 10−4 although operations like addition have a relative precision of 1 · 10−6 .
Note that the library has not really been tested together with any drawing operations. It should be used
to work with arbitrary input data which is then transformed somehow into pgf precision. This, in turn, can
be processed by pgf.
54.2
Usage
(default true)
/pgf/fpu={hbooleani}
This key installs or uninstalls the FPU. The installation exchanges any routines of the standard math
parser with those of the FPU: \pgfmathadd will be replaced with \pgfmathfloatadd and so on. Furthermore, any number will be parsed with \pgfmathfloatparsenumber.
1Y2.0e0]
\pgfkeys{/pgf/fpu}
\pgfmathparse{1+1}\pgfmathresult
The FPU uses a lowlevel number representation consisting of flags, mantissa and exponent9 . To avoid
unnecessary format conversions, \pgfmathresult will usually contain such a cryptic number. Depending
on the context, the result may need to be converted into something which is suitable for pgf processing
(like coordinates) or may need to be typeset. The FPU provides such methods as well.
Use fpu=false to deactivate the FPU. This will restore any change. Please note that this is not
necessary if the FPU is used inside of a TEX group – it will be deactivated afterwards anyway.
It does not hurt to call fpu=true or fpu=false multiple times.
Please note that if the fixed point arithmetics library of pgf will be activated after the FPU, the
FPU will be deactivated automatically.
(no default, initially float)
/pgf/fpu/output format=float|sci|fixed
This key allows to change the number format in which the FPU assigns \pgfmathresult.
The predefined choice float uses the low-level format used by the FPU. This is useful for further
processing inside of any library.
1Y2.17765411e23]
\pgfkeys{/pgf/fpu,/pgf/fpu/output format=float}
\pgfmathparse{exp(50)*42}\pgfmathresult
The choice sci returns numbers in the format hmantissaiehexponenti. It provides almost no computational overhead.
8 To be more precise, the FPU’s exponent is currently a 32 bit integer. That means it supports a significantly larger data
range than an IEEE double precision number – but if a future TEX version may provide lowlevel access to doubles, this may
change.
9 Users should always use high level routines to manipulate floating point numbers as the format may change in a future
release.
627
5.6154816e14
\pgfkeys{/pgf/fpu,/pgf/fpu/output format=sci}
\pgfmathparse{4.22e-8^-2}\pgfmathresult
The choice fixed returns normal fixed point numbers and provides the highest compatibility with the
pgf engine. It is activated automatically in case the FPU scales results.
0.000000999985
\pgfkeys{/pgf/fpu,/pgf/fpu/output format=fixed}
\pgfmathparse{sqrt(1e-12)}\pgfmathresult
(no default)
/pgf/fpu/scale results={hscalei}
A feature which allows semi-automatic result scaling. Setting this key has two effects: first, the output
format for any computation will be set to fixed (assuming results will be processed by pgf’s kernel).
Second, any expression which starts with a star, *, will be multiplied with hscalei.
(no default)
(no default)
(no default)
/pgf/fpu/scale file plot x={hscalei}
/pgf/fpu/scale file plot y={hscalei}
/pgf/fpu/scale file plot z={hscalei}
These keys will patch pgf’s plot file command to automatically scale single coordinates by hscalei.
The initial setting does not scale plot file.
\pgflibraryfpuifactive{htrue-codei}{hfalse-codei}
This command can be used to execute either htrue-codei or hfalse-codei, depending on whether the FPU
has been activated or not.
54.3
Comparison to the fixed point arithmetics library
There are other ways to increase the data range and/or the precision of pgf’s math parser. One of them is
the fp package, preferable combined with pgf’s fixed point arithmetic library. The differences between
the FPU and fp are:
• The FPU supports at least the complete IEEE double precision number range, while fp covers only
numbers of magnitude ±1 · 1017 .
• The FPU has a uniform relative precision of about 4–5 correct digits. The fixed point library has an
absolute precision which may perform good in many cases – but will fail at the ends of the data range
(as every fixed point routines does).
• The FPU has potential to be faster than fp as it has access to fast mantissa operations using pgf’s
math capabilities (which use TEX registers).
54.4
54.4.1
Command Reference and Programmer’s Manual
Creating and Converting Floats
\pgfmathfloatparsenumber{hx i}
Reads a number of arbitrary magnitude and precision and stores its result into \pgfmathresult as
floating point number m · 10e with mantissa and exponent base 10.
The algorithm and the storage format is purely text-based. The number is stored as a triple of flags, a
positive mantissa and an exponent, such as
1Y2.0e0]
\pgfmathfloatparsenumber{2}
\pgfmathresult
Please do not rely on the low-level representation here, use \pgfmathfloattomacro (and its variants)
and \pgfmathfloatcreate if you want to work with these components.
The flags encoded in \pgfmathresult are represented as a digit where ‘0’ stands for the number ±0·100 ,
‘1’ stands for a positive sign, ‘2’ means a negative sign, ‘3’ stands for ‘not a number’, ‘4’ means +∞
and ‘5’ stands for −∞.
The mantissa is a normalized real number m ∈ R, 1 ≤ m < 10. It always contains a period and at least
one digit after the period. The exponent is an integer.
628
Examples:
Flags: 0; Mantissa 0.0; Exponent 0.
\pgfmathfloatparsenumber{0}
\pgfmathfloattomacro{\pgfmathresult}{\F}{\M}{\E}
Flags: \F; Mantissa \M; Exponent \E.
Flags: 1; Mantissa 2.0; Exponent -1.
\pgfmathfloatparsenumber{0.2}
\pgfmathfloattomacro{\pgfmathresult}{\F}{\M}{\E}
Flags: \F; Mantissa \M; Exponent \E.
Flags: 1; Mantissa 4.2; Exponent 1.
\pgfmathfloatparsenumber{42}
\pgfmathfloattomacro{\pgfmathresult}{\F}{\M}{\E}
Flags: \F; Mantissa \M; Exponent \E.
Flags: 1; Mantissa 2.05; Exponent 3.
\pgfmathfloatparsenumber{20.5E+2}
\pgfmathfloattomacro{\pgfmathresult}{\F}{\M}{\E}
Flags: \F; Mantissa \M; Exponent \E.
Flags: 1; Mantissa 1.0; Exponent 6.
\pgfmathfloatparsenumber{1e6}
\pgfmathfloattomacro{\pgfmathresult}{\F}{\M}{\E}
Flags: \F; Mantissa \M; Exponent \E.
Flags: 1; Mantissa 5.21513; Exponent -11.
\pgfmathfloatparsenumber{5.21513e-11}
\pgfmathfloattomacro{\pgfmathresult}{\F}{\M}{\E}
Flags: \F; Mantissa \M; Exponent \E.
The argument hx i may be given in fixed point format or the scientific “e” (or “E”) notation. The scientific
notation does not necessarily need to be normalized. The supported exponent range is (currently) only
limited by the TEX-integer range (which uses 31 bit integer numbers).
/pgf/fpu/handlers/empty number={hinputi}{hunreadable parti}
(no default)
This command key is invoked in case an empty string is parsed inside of \pgfmathfloatparsenumber.
You can overwrite it to assign a replacement \pgfmathresult (in float!).
The initial setting is to invoke invalid number, see below.
/pgf/fpu/handlers/invalid number={hinputi}{hunreadable parti}
(no default)
This command key is invoked in case an invalid string is parsed inside of \pgfmathfloatparsenumber.
You can overwrite it to assign a replacement \pgfmathresult (in float!).
The initial setting is to generate an error message.
/pgf/fpu/handlers/wrong lowlevel format={hinputi}{hunreadable parti}
(no default)
This command key is invoked whenever \pgfmathfloattoregisters or its variants encounter something
which is not a properly formatted lowlevel floating point number. As for invalid number, this key may
assign a new \pgfmathresult (in floating point) which will be used instead of the offending hinputi.
The initial setting is to generate an error message.
\pgfmathfloatqparsenumber{hx i}
The same as \pgfmathfloatparsenumber, but does not perform sanity checking.
\pgfmathfloattofixed{hx i}
Converts a number in floating point representation to a fixed point number. It is a counterpart to
\pgfmathfloatparsenumber. The algorithm is purely text based and defines \pgfmathresult as a
629
string sequence which represents the floating point number hx i as a fixed point number (of arbitrary
precision).
Flags: 1; Mantissa 5.2; Exponent -4→0.00052
\pgfmathfloatparsenumber{0.00052}
\pgfmathfloattomacro{\pgfmathresult}{\F}{\M}{\E}
Flags: \F; Mantissa \M; Exponent \E
$\to$
\pgfmathfloattofixed{\pgfmathresult}
\pgfmathresult
Flags: 1; Mantissa 1.23456; Exponent 6→1234560.00000000
\pgfmathfloatparsenumber{123.456e4}
\pgfmathfloattomacro{\pgfmathresult}{\F}{\M}{\E}
Flags: \F; Mantissa \M; Exponent \E
$\to$
\pgfmathfloattofixed{\pgfmathresult}
\pgfmathresult
\pgfmathfloattoint{hx i}
Converts a number from low-level floating point representation to an integer (by truncating the fractional
part).
123456
\pgfmathfloatparsenumber{123456}
\pgfmathfloattoint{\pgfmathresult}
\pgfmathresult
See also \pgfmathfloatint which returns the result as float.
\pgfmathfloattosci{hfloati}
Converts a number from low-level floating point representation to scientific format, 1.234e4. The result
will be assigned to the macro \pgfmathresult.
\pgfmathfloatvalueof{hfloati}
Expands a number from low-level floating point representation to scientific format, 1.234e4.
Use \pgfmathfloatvalueof in contexts where only expandable macros are allowed.
\pgfmathfloatcreate{hflagsi}{hmantissai}{hexponenti}
Defines \pgfmathresult as the floating point number encoded by hflagsi, hmantissai and hexponenti.
All arguments are characters and will be expanded using \edef.
Flags: 1; Mantissa 1.0; Exponent 327
\pgfmathfloatcreate{1}{1.0}{327}
\pgfmathfloattomacro{\pgfmathresult}{\F}{\M}{\E}
Flags: \F; Mantissa \M; Exponent \E
\pgfmathfloatifflags{hfloating point number i}{hflagi}{htrue-codei}{hfalse-codei}
Invokes htrue-codei if the flag of hfloating point number i equals hflagi and hfalse-codei otherwise.
The argument hflagi can be one of
0 to test for zero,
1 to test for positive numbers,
+ to test for positive numbers,
2 to test for negative numbers,
- to test for negative numbers,
3 for “not-a-number”,
4 for +∞,
630
5 for −∞.
It’s not zero!It’s positive!It’s not negative!It’s positive!It’s not negative!
\pgfmathfloatparsenumber{42}
\pgfmathfloatifflags{\pgfmathresult}{0}{It’s zero!}{It’s not zero!}
\pgfmathfloatifflags{\pgfmathresult}{1}{It’s positive!}{It’s not positive!}
\pgfmathfloatifflags{\pgfmathresult}{2}{It’s negative!}{It’s not negative!}
% or, equivalently
\pgfmathfloatifflags{\pgfmathresult}{+}{It’s positive!}{It’s not positive!}
\pgfmathfloatifflags{\pgfmathresult}{-}{It’s negative!}{It’s not negative!}
\pgfmathfloattomacro{hx i}{hflagsmacroi}{hmantissamacroi}{hexponentmacroi}
Extracts the flags of a floating point number hx i to hflagsmacroi, the mantissa to hmantissamacroi and
the exponent to hexponentmacroi.
\pgfmathfloattoregisters{hx i}{hflagscounti}{hmantissadimeni}{hexponentcounti}
Takes a floating point number hx i as input and writes flags to count register hflagscounti, mantissa to
dimen register hmantissadimeni and exponent to count register hexponentcounti.
Please note that this method rounds the mantissa to TEX-precision.
\pgfmathfloattoregisterstok{hx i}{hflagscounti}{hmantissatoksi}{hexponentcounti}
A variant of \pgfmathfloattoregisters which writes the mantissa into a token register. It maintains
the full input precision.
\pgfmathfloatgetflags{hx i}{hflagscounti}
Extracts the flags of hx i into the count register hflagscounti.
\pgfmathfloatgetflagstomacro{hx i}{hmacroi}
Extracts the flags of hx i into the macro hmacroi.
\pgfmathfloatgetmantissa{hx i}{hmantissadimeni}
Extracts the mantissa of hx i into the dimen register hmantissadimeni.
\pgfmathfloatgetmantissatok{hx i}{hmantissatoksi}
Extracts the mantissa of hx i into the token register hmantissatoksi.
\pgfmathfloatgetexponent{hx i}{hexponentcounti}
Extracts the exponent of hx i into the count register hexponentcounti.
54.4.2
Symbolic Rounding Operations
Commands in this section constitute the basic level implementations of the rounding routines. They work
symbolically, i.e. they operate on text, not on numbers and allow arbitrarily large numbers.
\pgfmathroundto{hx i}
Rounds a fixed point number to prescribed precision and writes the result to \pgfmathresult.
The desired precision can be configured with /pgf/number format/precision, see section 92. This
section does also contain application examples.
Any trailing zeros after the period are discarded. The algorithm is purely text based and allows to deal
with precisions beyond TEX’s fixed point support.
As a side effect, the global boolean \ifpgfmathfloatroundhasperiod will be set to true if and only if
the resulting mantissa has a period. Furthermore, \ifpgfmathfloatroundmayneedrenormalize will be
set to true if and only if the rounding result’s floating point representation would have a larger exponent
than hx i.
1
\pgfmathroundto{1}
\pgfmathresult
631
4.69
20000
\pgfmathroundto{4.685}
\pgfmathresult
\pgfmathroundto{19999.9996}
\pgfmathresult
\pgfmathroundtozerofill{hx i}
A variant of \pgfmathroundto which always uses a fixed number of digits behind the period. It fills
missing digits with zeros.
1.00
\pgfmathroundtozerofill{1}
\pgfmathresult
4.69
\pgfmathroundto{4.685}
\pgfmathresult
20000.00
\pgfmathroundtozerofill{19999.9996}
\pgfmathresult
\pgfmathfloatround{hx i}
Rounds a normalized floating point number to a prescribed precision and writes the result to \pgfmathresult.
The desired precision can be configured with /pgf/number format/precision, see section 92.
This method employs \pgfmathroundto to round the mantissa and applies renormalization if necessary.
As a side effect, the global boolean \ifpgfmathfloatroundhasperiod will be set to true if and only if
the resulting mantissa has a period.
5.26e1
\pgfmathfloatparsenumber{52.5864}
\pgfmathfloatround{\pgfmathresult}
\pgfmathfloattosci{\pgfmathresult}
\pgfmathresult
1e1
\pgfmathfloatparsenumber{9.995}
\pgfmathfloatround{\pgfmathresult}
\pgfmathfloattosci{\pgfmathresult}
\pgfmathresult
\pgfmathfloatroundzerofill{hx i}
A variant of \pgfmathfloatround produces always the same number of digits after the period (it
includes zeros if necessary).
54.4.3
5.26e1
\pgfmathfloatparsenumber{52.5864}
\pgfmathfloatroundzerofill{\pgfmathresult}
\pgfmathfloattosci{\pgfmathresult}
\pgfmathresult
1.00e1
\pgfmathfloatparsenumber{9.995}
\pgfmathfloatroundzerofill{\pgfmathresult}
\pgfmathfloattosci{\pgfmathresult}
\pgfmathresult
Math Operations Commands
This section describes some of the replacement commands in more detail.
Please note that these commands can be used even if the fpu as such has not been activated – it is
sufficient to load the library.
632
\pgfmathfloathopi
Methods of this form constitute the replacement operations where hopi can be any of the well-known
math operations.
Thus, \pgfmathfloatadd is the counterpart for \pgfmathadd and so on. The semantics and number of
arguments is the same, but all input and output arguments are expected to be floating point numbers.
\pgfmathfloattoextentedprecision{hx i}
Renormalizes hx i to extended precision mantissa, meaning 100 ≤ m < 1000 instead of 1 ≤ m < 10.
The “extended precision” means we have higher accuracy when we apply pgfmath operations to mantissas.
The input argument is expected to be a normalized floating point number; the output argument is a
non-normalized floating point number (well, normalized to extended precision).
The operation is supposed to be very fast.
\pgfmathfloatsetextprecision{hshifti}
Sets the precision used inside of \pgfmathfloattoextentedprecision to hshifti.
The
0
1
2
3
different choices are
normalization to
0
normalization to
10
normalization to
100
normalization to 1000
≤m<1
≤ m < 100
≤ m < 1000
≤ m < 10000
(disable extended precision)
(default of \pgfmathfloattoextentedprecision)
\pgfmathfloatlessthan{hx i}{hyi}
Defines \pgfmathresult as 1.0 if hx i < hyi, but 0.0 otherwise. It also sets the global TEX-boolean \pgfmathfloatcomparison accordingly. The arguments hx i and hyi are expected to be numbers which have
already been processed by \pgfmathfloatparsenumber. Arithmetic is carried out using TEX-registers
for exponent- and mantissa comparison.
\pgfmathfloatmultiplyfixed{hfloati}{hfixed i}
Defines \pgfmathresult to be hfloati · hfixed i where hfloati is a floating point number and hfixed i is a
fixed point number. The computation is performed in floating point arithmetics, that means we compute
m · hfixed i and renormalize the result where m is the mantissa of hfloati.
This operation renormalizes hfloati with \pgfmathfloattoextentedprecision before the operation,
that means it is intended for relatively small arguments of hfixed i. The result is a floating point number.
\pgfmathfloatifapproxequalrel{hai}{hbi}{htrue-codei}{hfalse-codei}
Computes the relative error between hai and hbi (assuming hbi6= 0) and invokes htrue-codei if the relative
error is below /pgf/fpu/rel thresh and hfalse-codei if that is not the case.
The input arguments will be parsed with \pgfmathfloatparsenumber.
/pgf/fpu/rel thresh={hnumber i}
(no default, initially 1e-4)
A threshold used by \pgfmathfloatifapproxequalrel to decide whether numbers are approximately equal.
\pgfmathfloatshift{hx i}{hnumi}
Defines \pgfmathresult to be hx i · 10hnumi . The operation is an arithmetic shift base ten and modifies
only the exponent of hx i. The argument hnumi is expected to be a (positive or negative) integer.
\pgfmathfloatabserror{hx i}{hyi}
Defines \pgfmathresult to be the absolute error between two floating point numbers x and y, |x − y|
and returns the result as floating point number.
\pgfmathfloatrelerror{hx i}{hyi}
Defines \pgfmathresult to be the relative error between two floating point numbers x and y, |x − y|/|y|
and returns the result as floating point number.
633
\pgfmathfloatint{hx i}
Returns the integer part of the floating point number hx i, by truncating any digits after the period.
This methods truncates the absolute value |x| to the next smaller integer and restores the original sign
afterwards.
The result is returned as floating point number as well.
See also \pgfmathfloattoint which returns the number in integer format.
\pgfmathlog{hx i}
Defines \pgfmathresult to be the natural logarithm of hx i, ln(hx i). This method is logically the same
as \pgfmathln, but it applies floating point arithmetics to read number hx i and employs the logarithm
identity
ln(m · 10e ) = ln(m) + e · ln(10)
to get the result. The factor ln(10) is a constant, so only ln(m) with 1 ≤ m < 10 needs to be computed.
This is done using standard pgf math operations.
Please note that hx i needs to be a number, expression parsing is not possible here.
If hx i is not a bounded positive real number (for example hx i ≤ 0), \pgfmathresult will be empty, no
error message will be generated.
54.4.4
-15.7452
\pgfmathlog{1.452e-7}
\pgfmathresult
20.28096
\pgfmathlog{6.426e+8}
\pgfmathresult
Accessing the Original Math Routines for Programmers
As soon as the library is loaded, every private math routine will be copied to a new name. This allows
library and package authors to access the TEX-register based math routines even if the FPU is activated.
And, of course, it allows the FPU as such to perform its own mantissa computations.
The private implementations of pgf math commands, which are of the form \pgfmathhnamei@, will be
available as\pgfmath@basic@hnamei@ as soon as the library is loaded.
634
55
Lindenmayer System Drawing Library
55.1
Overview
Lindenmayer systems (also commonly known as “L-systems”), were originally developed by Aristid Lindenmayer as a theory of algae growth patterns and then subsequently used to model branching patterns in
plants and produce fractal patterns. Typically, an L-system consists of a set of symbols, each of which is
associated with some graphical action (such as “turn left” or “move forward”) and a set of rules (“production”
or “rewrite” rules). Given a string of symbols, the rewrite rules are applied several times and the when
resulting string is processed the action associated with each symbol is executed.
In pgf, L-systems can be used to create simple 2-dimensional fractal patterns. . .
\begin{tikzpicture}
\pgfdeclarelindenmayersystem{Koch curve}{
\rule{F -> F-F++F-F}
}
\shadedraw [top color=white, bottom color=blue!50, draw=blue!50!black]
[l-system={Koch curve, step=2pt, angle=60, axiom=F++F++F, order=3}]
lindenmayer system -- cycle;
\end{tikzpicture}
. . . and “plant like” patterns. . .
\begin{tikzpicture}
\draw [green!50!black, rotate=90]
[l-system={rule set={F -> FF-[-F+F]+[+F-F]}, axiom=F, order=4, step=2pt,
randomize step percent=25, angle=30, randomize angle percent=5}]
lindenmayer system;
\end{tikzpicture}
. . . but it is important to bear in mind that even moderately complex L-systems can exceed the available
memory of TEX, and can be very slow. If possible, you are advised to increase the main memory and save
stack to their maximum possible values for your particular TEX distribution. However, even by doing this
you may find you still run out of memory quite quickly.
For an excellent introduction to L-systems (containing some “really cool” pictures – many of which are
sadly not possible in pgf) see The Algorithmic Beauty of Plants by Przemyslaw Prusinkiewicz and Aristid
Lindenmayer (which is freely available via the internet).
Tik Z Library lindenmayersystems
\usepgflibrary{lindenmayersystems}
\usepgflibrary[lindenmayersystems]
\usetikzlibrary{lindenmayersystems}
\usetikzlibrary[lindenmayersystems]
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This pgf-library provides basic commands for defining and using simple L-systems. The Tik Z-library
provides, furthermore, a front end for using L-systems in Tik Z.
55.1.1
%
%
%
%
Declaring L-systems
Before an L-system can be used, it must be declared using the following command:
\pgfdeclarelindenmayersystem{hnamei}{hspecificationi}
This command declares a Lindenmayer system called hnamei. The hspecificationi argument contains a
description of the L-system’s symbols and rules. Two commands \symbol and \rule are only defined
when the hspecificationi argument is executed.
\symbol{hnamei}{hcodei}
This defines a symbol called hnamei for a specific L-system, and associates it with hcodei.
A symbol should consist of a single alpha-numeric character (i.e., A-Z, a-z or 0-9). The symbols F,
f, +, -, [ and ] are available by default so do not need to be defined for each L-system. However, if
you are feeling adventurous, they can be redefined for specific L-systems if required. The L-system
treats the default symbols as follows (the commands they execute are described below):
635
•
•
•
•
•
•
F
f
+
[
]
move forward a certain distance, drawing a line. Uses \pgflsystemdrawforward.
move forward a certain distance, without drawing a line. Uses \pgflsystemmoveforward.
turn left by some angle. Uses \pgflsystemturnleft.
turn right by some angle. Uses \pgflsystemturnright.
save the current state (i.e., the position and direction). Uses \pgflsystemsavestate.
restore the last saved state. Uses \pgflsystemrestorestate.
The symbols [ and ] act like a stack: [ pushes the state of the L-system on to the stack, and ]
pops a state off the stack.
When hcodei is executed, the transformation matrix is set up so that the origin is at the current position and the positive x-axis “points forward”, so \pgfpathlineto{\pgfpoint{1cm}{0cm}} draws
a line 1cm forward.
The following keys can alter the production of an L-system. However, they do not store values in
themselves.
/pgf/lindenmayer system/step=hlengthi
(no default, initially 5pt)
How far the L-system moves forward if required. This key sets the TEX dimension \pgflsystemstep.
/pgf/lindenmayer system/randomize step percent=hpercentagei
(no default, initially 0)
If the step is to be randomized, this key specifies by how much. The value is stored in the TEX
macro \pgflsystemrandomizesteppercent.
/pgf/lindenmayer system/left angle=hanglei
(no default, initially 90)
This key sets the angle through which the L-system turns when it turns left. The value is
stored in the TEX macro \pgflsystemrleftangle.
/pgf/lindenmayer system/right angle=hanglei
(no default, initially 90)
This key sets the angle through which the L-system turns when it turns right. The value is
stored in the TEX macro \pgflsystemrrightangle.
/pgf/lindenmayer system/randomize angle percent=hpercentagei
(no default, initially 0)
If the angles are to be randomized, this key specifies by how much. The value is stored in the
TEX macro \pgflsystemrandomizeanglepercent.
For speed and convenience, when the code for a symbol is executed, the following commands are
available.
\pgflsystemcurrentstep
The current “step” of the L-system (i.e., how far the system will move forward if required).
This is initially set to the value in the TEX-dimensions \pgflsystemstep, but the actual value
may be changed if \pgflsystemrandomizestep is used (see below).
\pgflsystemcurrentleftangle
The angle the L-system will turn when it turns left. The value stored in this macro may be
changed if \pgflsystemrandomizeleftangle is used.
\pgflsystemcurrentrightangle
The angle the L-system will turn when it turns right. The value stored in this macro may be
changed if \pgflsystemrandomizerightangle is used.
The following commands may be useful if you wish to define your own symbols.
\pgflsystemrandomizestep
Randomizes the value in \pgflsystemcurrentstep according to the current value of the key
randomize step percent.
\pgflsystemrandomizeleftangle
Randomizes the value in \pgflsystemcurrentleftangle according to the value of the
randomize angle percent key.
\pgflsystemrandomizerightangle
636
Randomizes the value in \pgflsystemcurrentrightangle according to the value of the randomize angle key.
\pgflsystemdrawforward
Move forward in the current direction, by \pgflsystemcurrentstep, drawing a line in the process. This macro calls \pgflsystemrandomizestep. Internally, pgf simply shifts the transformation matrix in the positive direction of the current (transformed) x-axis by \pgflsystemstep
and then executes a line-to to the (newly transformed) origin.
\pgflsystemmoveforward
Move forward in the current direction, by \pgflsystemcurrentstep, without drawing a line.
This macro calls \pgflsystemrandomizestep. pgf executes a transformation as above, but
executes a move-to to the (newly transformed) origin.
\pgflsystemturnleft
Turn left by \pgflsystemcurrentleftangle. Internally, pgf simply rotates the transformation matrix. This macro calls \pgflsystemrandomizeleftangle.
\pgflsystemturnright
Turn right by \pgflsystemcurrentrightangle. Internally, pgf simply rotates the transformation matrix. This macro calls \pgflsystemrandomizerightangle.
\pgflsystemsavestate
Save the current position and orientation. Internally, pgf simply starts a new TEX-group.
\pgflsystemrestorestate
Restore the last saved position and orientation. Internally, pgf closes a TEX-group, restoring
the transformation matrix of the outer scope, and a move-to command is executed to the
(transformed) origin.
\rule{hhead i->hbodyi}
Declare a rule. hhead i should consist of a single symbol, which need not have been declared using
\symbol or exist as a default symbol (in fact, the more interesting L-systems depend on using
symbols with no corresponding code, to control the “growth” of the system). hbodyi consists of a
string of symbols, which again need not necessarily have any code associated with them.
As an example, the following shows an L-system that uses some of these commands. This example
illustrates the point that some symbols, in this case A and B, do not have to have code associated with
them. They simply control the growth of the system.
\pgfdeclarelindenmayersystem{Hilbert curve}{
\symbol{X}{\pgflsystemdrawforward}
\symbol{+}{\pgflsystemturnright} % Explicitly define + and - symbols.
\symbol{-}{\pgflsystemturnleft}
\rule{A -> +BX-AXA-XB+}
\rule{B -> -AX+BXB+XA-}
}
\tikz\draw[lindenmayer system={Hilbert curve, axiom=A, order=4, angle=90}]
lindenmayer system;
55.2
55.2.1
Using Lindenmayer Systems
Using L-Systems in PGF
The following command is used to run an L-system in pgf:
\pgflindenmayersystem{hnamei}{haxiomi}{horder i}
Runs the L-system called hnamei using the input string haxiomi for horder i iterations. In general,
prior to calling this command, the transformation matrix should be set appropriately for shifting and
rotating, and a move-to to the (transformed) origin should be executed. This origin will be where the
L-system starts. In addition, the relevant keys should be set appropriately.
637
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\pgfset{lindenmayer system/.cd, angle=60, step=2pt}
\foreach \x/\y in {0cm/1cm, 1.5cm/1.5cm, 2.5cm/0.5cm, 1cm/0cm}{
\pgftransformshift{\pgfqpoint{\x}{\y}}
\pgfpathmoveto{\pgfpointorigin}
\pgflindenmayersystem{Koch curve}{F++F++F}{2}
\pgfusepath{stroke}
}
\end{tikzpicture}
Note that it is perfectly feasible for an L-system to define special symbols which perform the move-to
and use-path operations.
55.2.2
Using L-Systems in Tik Z
In Tik Z, an L-system is created using a path operation. However, Tik Z is more flexible regarding the
positioning of the L-system and also provides keys to create L-systems “on-line”.
\path . . . lindenmayer system [hkeysi] . . . ;
This will run an L-system according to the parameters specified in hkeysi (which can also contain normal
keys such as draw or thin). The syntax is flexible regarding the L-system parameters and the following
all do the same thing:
\draw lindenmayer system [lindenmayer system={Hilbert curve, axiom=4, order=3}];
\draw [lindenmayer system={Hilbert curve, axiom=4, order=3}] lindenmayer system;
\tikzset{lindenmayer system={Hilbert curve, axiom=4, order=3}}
\draw lindenmayer system;
\path . . . l-system [hkeysi] . . . ;
A more compact version of the lindenmayer system path command.
This library adds some additional keys for specifying L-systems. These keys only work in Tik Z and all
have the same path, namely, /pgf/lindenmayer system, but the following keys are provided for convenience,
so that you do not have to keep repeating this path:
(style, no default)
/pgf/lindenmayer system={hkeysi}
alias /tikz/lindenmayer system
This key changes the key path to /pgf/lindenmayer systems and executes hkeysi.
(style, no default)
/pgf/l-system={hkeysi}
alias /tikz/l-system
A more compact version of the previous key.
(no default)
/pgf/lindenmayer system/name={hnamei}
Sets the name for the L-system.
(no default)
/pgf/lindenmayer system/axiom={hstringi}
Sets the axiom (or input string) for the L-system.
/pgf/lindenmayer system/order={hinteger i}
(no default)
Sets the number of iterations the L-system will perform.
(no default)
/pgf/lindenmayer system/rule set={hlisti}
This key allows an (anonymous) L-system to be declared “on-line”. There is, however, a restriction that
only the default symbols can be used for drawing (empty symbols can still be used to control the growth
of the system). The rules in hlisti should be separated by commas.
638
\tikz[rotate=65]\draw [green!60!black] l-system
[l-system={rule set={F -> F[+F]F[-F]}, axiom=F, order=4, angle=25,step=3pt}];
/pgf/lindenmayer system/anchor=hanchor i
(no default)
Be default, when this key is not used, the L-system will start from the last specified coordinate. By
using this key, the L-system will be placed inside a special (rectangle) node which can be positioned
using hanchor i.
\begin{tikzpicture}[l-system={step=1.75pt, order=5, angle=60}]
\pgfdeclarelindenmayersystem{Sierpinski triangle}{
\symbol{X}{\pgflsystemdrawforward}
\symbol{Y}{\pgflsystemdrawforward}
\rule{X -> Y-X-Y}
\rule{Y -> X+Y+X}
}
\draw [help lines] grid (3,2);
\draw [red] (0,0) l-system
[l-system={Sierpinski triangle, axiom=+++X, anchor=south west}];
\draw [blue] (3,2) l-system
[l-system={Sierpinski triangle, axiom=X, anchor=north east}];
\end{tikzpicture}
639
56
Math Library
Tik Z Library math
\usetikzlibrary{math} % LATEX and plain TEX
\usetikzlibrary[math] % ConTEXt
This library defines a simple mathematical language to define simple functions and perform sequences
of basic mathematical operations.
56.1
Overview
pgf and Tik Z both use the pgf mathematical engine which provides many commands for parsing expressions.
Unfortunately the pgf math engine is somewhat cumbersome for long sequences of mathematical operations,
particularly when assigning values to multiple variables. The Tik Z calc library provides some additional
“convenience” operations for doing calculations (particularly with coordinates), but this can only be used
inside Tik Z path commands.
This math library provides a means to perform sequences of mathematical operations in a more ‘user
friendly’ manner than the pgf math engine. In addition, the coordinate calculations of the calc library can
be accessed (provided it is loaded). However as the math library uses the pgf math engine – which uses
pure TEX to perform all its calculations – it is subject to the same speed and accuracy limitations. It is
worth bearing this in mind, before trying to implement algorithms requiring intensive and highly accurate
computation. You can, of course use the fp or the fpu libraries to increase the accuracy (but not necessarily
the speed) of computations.
For most purposes, the features provided by this library are accessed using the following command:
\tikzmath{hstatementsi}
This command process a series of hstatementsi which can represent assignments, function definitions,
conditional evaluation, and iterations. It provides, in effect, a miniature mathematical language to
perform basic mathematical operations. Perhaps the most important thing to remember is that every
statement should end with a semi-colon. This is likely to be the most common reason why the \tikzmath
command fails.
0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765,
\tikzmath{
% Adapted from http://www.cs.northwestern.edu/academics/courses/110/html/fib_rec.html
function fibonacci(\n) {
if \n == 0 then {
return 0;
} else {
return fibonacci2(\n, 0, 1);
};
};
function fibonacci2(\n, \p, \q) {
if \n == 1 then {
return \q;
} else {
return fibonacci2(\n-1, \q, \p+\q);
};
};
int \f, \i;
for \i in {0,1,...,20}{
\f = fibonacci(\i);
print {\f, };
};
}
In addition to this command the following key is provided:
(no default)
/tikz/evaluate=hstatementsi
This key simply executes \tikzmath{hstatementsi}.
640
\tikz[x=0.25cm,y=0.25cm,
evaluate={
int \i, \j;
for \i in {0,...,10}{
for \j in {0,...,10}{
\a{\i,\j} = (\i+\j)*5;
};
};
}
]
\foreach \i in {0,...,10}
\foreach \j in {0,...,10}
\fill [red!\a{\i,\j}!yellow]
(\i,\j) rectangle ++(1, 1);
The following sections describe the miniature language that this library provides and can be used in the
\tikzmath command and the evaluate key. The language consists only of simple keywords and expressions
but the mini-parser allows you to format code in a reasonably versatile way (much like the tikz parser)
except that all the keywords must be followed by at least one space. This is the second most important thing
to remember (after remembering to insert semi-colons at the end of every statement).
56.2
Assignment
In the simplest case, you will want to evaluate an expression and assign it to a macro, or a TEX count or
dimension register. In this case, use of the math library is straightforward:
26.0, 2.0, 11, 225.0pt
\newcount\mycount
\newdimen\mydimen
\tikzmath{
\a = 4*5+6;
\b = sin(30)*4;
\mycount = log10(2048) / log10(2);
\mydimen = 15^2;
}
\a, \b, \the\mycount, \the\mydimen
In addition, TEX-macros (not TEX registers) can be suffixed with an index, similar to indices in mathematical notation, for example, x1 , x2 , x3 :
7.0, 70.0, 700.0
\tikzmath{
\x1 = 3+4; \x2 = 30+40; \x3 = 300+400;
}
\x1, \x2, \x3
The index does not have to be a number. By using braces {}, more sophisticated indices can be created:
The speed of sound in air is 340 m/s. The speed of sound in steel is 6100 m/s.
\tikzmath{
\c{air} = 340; \c{water} = 1435; \c{steel} = 6100;
}
\foreach \medium in {air,steel}{The speed of sound in \medium\ is \c{\medium} m/s. }
You should not, however, try to mix indexed and non-indexed variables. Once an assignment is made
using an index, the math library expects all instances of the variable on the right hand side of an assignment
to be followed by an index. This effect is reversed if you subsequently make an assignment to the variable
without an index: the math library (or to be precise the pgf math-engine) will then ignore any index
following the variable on the right hand side of an assignment.
In some cases, you may wish to assign a value or expression to a variable without evaluating it with the
pgf math-engine. In this case, you can use the following keyword:
let hvariablei = hexpressioni;
This keyword assigns hexpressioni to hvariablei without evaluation. The hexpressioni is however fully
expanded using \edef. Any spaces preceding hexpressioni are removed, but any trailing spaces (before
the semi-colon) are included.
641
(5*4)+1, “blue”
56.3
\tikzmath{
let \x = (5*4)+1;
let \c1 = blue;
}
\x, “\c1”
Integers, “Real” Numbers, and Coordinates
By default, assignments are made by evaluating expressions using the pgf math-engine and results are
usually returned as number with a decimal point (unless you are assigning to a count register or use the int
function). As this is not always desirable, the math library allows variables – which must be TEX macros –
to be ‘declared’ as being a particular ‘type’. The library recognizes three types: integers (numbers without
a decimal point), real numbers (numbers with a decimal point10 ), and coordinates.
To declare a variable as being one of the three types, you can use the keywords shown below. It is
important to remember that by telling the math library you want it to do a particular assignment for a
variable, it will also do the same assignment when the variable is indexed.
7, 70, 700
\tikzmath{
integer \x;
\x1 = 3+4; \x2 = 30+40; \x3 = 300+400;
}
\x1, \x2, \x3
integer hvariablei, hadditional variablesi;
The integer keyword indicates that assignments to the hvariablei or the comma separated list of
hadditional variablesi should be truncated (not rounded) to integers. The variables should be ordinary
macros – not TEX registers. In addition the variables should not be indexed.
x = 26, y = 2, z = 9
\tikzmath{
integer \x, \y, \z;
\x = 4*5+6;
\y = sin(30)*4;
\z = log10(512) / log10(2);
print {$x=\x$, $y=\y$, $z=\z$};
}
int hvariablei, hadditional variablesi;
Short version of the integer keyword.
Having declared a variable as an integer, the math library will continue to assign only integers to that
variable within the current TEX scope. If you wish to assign non-integer (i.e., real ) numbers to the same
variable, the following keyword can be used.
real hvariablei, hadditional variablesi;
The real keyword ensures that assignments hvariablei (and hadditional variablesi) will not be truncated
to integers.
In order to take advantage of math library interface to the calc library you must indicate that a variable
is to be assigned coordinates, using the following keyword.
coordinate hvariablei, hadditional variablesi;
This keyword enables Tik Z-style coordinates such as (2cm,3pt) or (my node.east) to be parsed and
assigned to hvariablei in the form x, y, which can then be used in a tikzpicture:
\tikzmath{
coordinate \c;
\c = (45:10pt);
}
\tikz\draw (0,0) -- (\c);
10 Strictly
speaking, due to the finite range and precision of TEX numerical capabilities, the term “real” is not correct.
642
If the Tik Z calc library is loaded, coordinate calculations can be performed; the coordinate expression
does not have to be surrounded by ($. . . $).
\tikzmath{
coordinate \c, \d;
\c = (-1,2)+(1,-1);
\d = (4,1)-(2,-1);
}
\tikz\draw (\c) -- (\d);
In addition to assigning the x and y coordinates to hvariablei (possibly with an optional index), two
further variables are defined. The first takes the name of hvariablei (e.g., \c) suffixed with x (i.e., \cx)
and is assigned the x coordinate of \c. The second takes the name of hvariablei suffixed with y (i.e.,
\cy) and is assigned the y coordinate of \c.
\tikzmath{
coordinate \c;
\c1 = (30:20pt);
\c2 = (210:20pt);
}
\tikz\draw (\cx1,\cy1) -- (\cx2,\cy1) -- (\cx2,\cy2) -- (\cx1,\cy2);
56.4
Repeating Things
for hvariablei in {hlisti}{hexpressionsi};
This is a “trimmed down” version of the \foreach command available as part of pgf and Tik Z, but
cannot currently be used outside of the \tikzmath command. It is important to note the following:
• Every value in hlisti is evaluated using the pgf mathematical engine. However, if an item in hlisti
contains a comma, it must be surrounded by braces, for example, {mod(5, 2)}.
x = 7, v = 128
\tikzmath{
int \x, \v;
\v=1;
for \x in {1,...,{random(3,10)}}{
\v=\v*2;
};
print {$x=\x, v=\v$};
}
• Because each item is evaluated, you cannot use Tik Z coordinates in hlisti.
• Only single variable assignment is supported.
• The “dots notation” (e. g., 1,2,...,9) can be used in hlisti, but is not as sophisticated as the pgf
\foreach command. In particular, contextual replacement is not possible.
• Assignments that occur in the loop body are not scoped. They last beyond the body of each
iteration and the end of the for statement. This includes the values assigned to the hvariablei.
x1 = 5, x2 = 50, y = 2250
56.5
\tikzmath{
int \x, \y;
\y = 0;
for \x1 in {1,...,5}{
for \x2 in {10,20,...,50}{
\y = \y+\x1*\x2;
};
};
}
$x_1=\x1, x_2=\x2, y=\y$
Branching Statements
Sometimes you may wish to execute different statements depending on the value of an expression. In this
case the following keyword can be used:
643
if hconditioni then {hif-non-zero-statementsi};
This keyword executes hif-non-zero-statementsi if the expression in hconditioni evaluates to any value
other than zero.
if hconditioni then {hif-non-zero-statementsi} else {hif-zero-statementsi};
This keyword executes hif-non-zero-statementsi if the expression in hconditioni evaluates to any value
other than zero and the hif-zero-statementsi are executed if the expression in hconditioni evaluates to
zero.
\begin{tikzpicture}
\tikzmath{
int \x;
for \k in {0,10,...,350}{
if \k>260 then { let \c = orange; } else
if \k>170 then { let \c = blue; } else
if \k>80 then { let \c = red; } else
let \c = green; }; }; };
{
\path [fill=\c!50, draw=\c] (\k:0.5cm)
(\k+5:1cm) -- (\k+5:0.5cm) -- cycle;
};
};
}
\end{tikzpicture}
56.6
{
{
{
-- (\k:1cm) --
Declaring Functions
You can add functions by using the following keywords:
function hnamei(hargumentsi) { hdefinitioni };
This keyword works much like the declare function provided by the pgf math-engine. The function
hnamei can be any name that is not already a function name in the current scope. The list of hargumentsi
are comma separated TEX macros such as \x, or \y (it is not possible to declare functions that take
variable numbers of arguments). If the function takes no arguments then the parentheses need not be
used. It is very important to note that the arrays that the pgf math engine supports cannot currently
be passed as arguments to functions.
The function hdefinitioni should be a sequence of statements that can be parsed by the \tikzmath
command and should use the commands specified in the hargumentsi. The return keyword (described
below) should be used to indicate the value returned by the function. Although hdefinitioni can take
any statements accepted by \tikzmath, it is not advisable try to define functions inside other functions.
4 × 27 = 108
\tikzmath{
function product(\x,\y) {
return \x*\y;
};
int \i, \i, \k;
\i = random(1,10);
\j = random(20, 40);
\k = product(\i, \j);
print { $\i\times \j = \k$ };
}
return hexpressioni;
This keyword should be used as the last executed statement in a function definition to indicate the value
that should be returned.
56.7
Executing Code Outside the Parser
Sometimes you may wish to do “something” outside the parser, perhaps display some intermediate result or
execute some code. In this case you have two options. Firstly, the following keyword can be used:
print {hcodei};
644
Execute hcodei immediately. This is intended as convenience keyword for displaying information in a
document (analogous to the print command in real programming languages). The hcodei is executed
inside a TEX group.
30 = 1, 31 = 3, 32 = 9, 33 = 27, 34 = 81, 35 = 243, 36 = 729,
\tikzmath{
int \x, \y, \z;
\x = random(2, 5);
for \y in {0,...,6}{
\z = \x^\y;
print {$\x^\y=\z$, };
};
}
Secondly, if a statement begins with a brace {, then everything up to the closing brace } is collected
and executed (the closing brace must be followed by a semi-colon). Like the print keyword, the contents
of the braces is executed inside a TEX group. Unlike the print keyword, the brace notation can be used in
functions so that tikz path commands can be safely executed inside a tikzpicture.
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\tikzmath{
coordinate \c;
for \x in {0,10,...,360}{
\c = (1.5cm, 1cm) + (\x:1cm and 0.5cm);
{ \fill (\c) circle [radius=1pt]; };
};
}
\end{tikzpicture}
645
57
Matrix Library
Tik Z Library matrix
\usetikzlibrary{matrix} % LATEX and plain TEX
\usetikzlibrary[matrix] % ConTEXt
This library package defines additional styles and options for creating matrices.
57.1
Matrices of Nodes
A matrix of nodes is a Tik Z matrix in which each cell contains a node. In this case it is bothersome having
to write \node{ at the beginning of each cell and }; at the end of each cell. The following key simplifies
typesetting such matrices.
(no value)
/tikz/matrix of nodes
Conceptually, this key adds \node{ at the beginning and }; at the end of each cell and sets the anchor
of the node to base. Furthermore, it adds the option name option to each node, where the name is set to
hmatrix namei-hrow number i-hcolumn number i. For example, if the matrix has the name my matrix,
then the node in the upper left cell will get the name my matrix-1-1.
8 1 6
3 5 7
4 9 2
\begin{tikzpicture}
\matrix (magic) [matrix of nodes]
{
8 & 1 & 6 \\
3 & 5 & 7 \\
4 & 9 & 2 \\
};
\draw[thick,red,->] (magic-1-1) |- (magic-2-3);
\end{tikzpicture}
You may wish to add options to certain nodes in the matrix. This can be achieved in three ways.
1. You can modify, say, the row 2 column 3 style to pass special options to this particular cell.
8 1 6
3 5 7
4 9 2
\begin{tikzpicture}[row 2 column 3/.style=red]
\matrix [matrix of nodes]
{
8 & 1 & 6 \\
3 & 5 & 7 \\
4 & 9 & 2 \\
};
\end{tikzpicture}
2. At the beginning of a cell, you can use a special syntax. If a cell starts with a vertical bar, then
everything between this bar and the next bar is passed on to the node command.
8 1 6
3 5 7
4 9 2
\begin{tikzpicture}
\matrix [matrix of nodes]
{
8 & 1 &
6 \\
3 & 5 & |[red]| 7 \\
4 & 9 &
2 \\
};
\end{tikzpicture}
You can also use an option like |[red] (seven)| to give a different name to the node.
Note that the & character also takes an optional argument, which is an extra column skip.
8
3
4
1
5
9
6
7
2
\begin{tikzpicture}
\matrix [matrix of nodes]
{
8 &[1cm] 1 &[3mm] |[red]| 6 \\
3 &
5 &
|[red]| 7 \\
4 &
9 &
2 \\
};
\end{tikzpicture}
646
3. If your cell starts with a \path command or any command that expands to \path, which includes
\draw, \node, \fill and others, the \node{ startup code and the }; code are suppressed. This
means that for this particular cell you can provide totally different contents.
8 1
3 5
6
7
4 9
2
\begin{tikzpicture}
\matrix [matrix of nodes]
{
8 & 1 & 6 \\
3 & 5 & \node[red]{7}; \draw(0,0) circle(10pt);\\
4 & 9 & 2 \\
};
\end{tikzpicture}
(no value)
/tikz/matrix of math nodes
This style is almost the same as the previous style, only $ is added at the beginning and at the end of
each node, so math mode will be switched on in all nodes.
a8 a1 a6
a3 a5 a7
a4 a9 a2
\begin{tikzpicture}
\matrix [matrix of math nodes]
{
a_8 & a_1 &
a_6 \\
a_3 & a_5 & |[red]| a_7 \\
a_4 & a_9 &
a_2 \\
};
\end{tikzpicture}
/tikz/nodes in empty cells=htrue or falsei
(default true)
When set to true, a node (with empty contents) is put in empty cells. Normally, empty cells
are just, well, empty. The style can be used together with both a matrix of nodes and a
matrix of math nodes.
a8
a6
a3
a7
a4
a8
a6
a3
a7
a4
57.2
a9
a9
\begin{tikzpicture}
\matrix [matrix of math nodes,nodes={circle,draw}]
{
a_8 &
& a_6 \\
a_3 &
& a_7 \\
a_4 & a_9 &
\\
};
\end{tikzpicture}
\begin{tikzpicture}
\matrix [matrix of math nodes,nodes={circle,draw},nodes in empty cells]
{
a_8 &
& a_6 \\
a_3 &
& a_7 \\
a_4 & a_9 &
\\
};
\end{tikzpicture}
End-of-Lines and End-of-Row Characters in Matrices of Nodes
Special care must be taken about the usage of the \\ command inside a matrix of nodes. The reason is that
this character is overloaded in TEX: On the one hand, it is used to denote the end of a line in normal text;
on the other hand it is used to denote the end of a row in a matrix. Now, if a matrix contains node which
in turn may have multiple lines, it is unclear which meaning of \\ should be used.
This problem arises only when you use the text width option of nodes. Suppose you write a line like
\matrix [text width=5cm,matrix of nodes]
{
first row & upper line \\ lower line \\
second row & hmm \\
};
This leaves TEX trying to riddle out how many rows this matrix should have. Do you want two rows
with the upper right cell containing a two-line text. Or did you mean a three row matrix with the second
row having only one cell?
Since TEX is not clairvoyant, the following rules are used:
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1. Inside a matrix, the \\ command, by default, signals the end of the row, not the end of a line in a cell.
2. However, there is an exception to this rule: If a cell starts with a TEX-group (this is, with {), then
inside this first group the \\ command retains the meaning of “end of line” character. Note that this
special rule works only for the first group in a cell and this group must be at the beginning.
The net effect of these rules is the following: Normally, \\ is an end-of-row indicator; if you want to use it
as an end-of-line indicator in a cell, just put the whole cell in curly braces. The following example illustrates
the difference:
row 1
upper line
lower line
row 2
hmm
row 1
\begin{tikzpicture}
\matrix [matrix of nodes,nodes={text width=16mm,draw}]
{
row 1 & upper line \\ lower line \\
row 2 & hmm \\
};
\end{tikzpicture}
\begin{tikzpicture}
\matrix [matrix of nodes,nodes={text width=16mm,draw}]
{
row 1 & {upper line \\ lower line} \\
row 2 & hmm \\
};
\end{tikzpicture}
upper line
lower line
hmm
row 2
Note that this system is not fool-proof. If you write things like a&b{c\\d}\\ in a matrix of nodes, an
error will result (because the second cell did not start with a brace, so \\ retained its normal meaning and,
thus, the second cell contained the text b{c, which is not balanced with respect to the number of braces).
57.3
Delimiters
Delimiters are parentheses or braces to the left and right of a formula or a matrix. The matrix library offers
options for adding such delimiters to a matrix. However, delimiters can actually be added to any node that
has the standard anchors north, south, north west and so on. In particular, you can add delimiters to any
rectangle box. They are implemented by “measuring the height” of the node and then adding a delimiter
of the correct size to the left or right using some after node magic.
/tikz/left delimiter=hdelimiter i
(no default)
This option can be given to a any node that has the standard anchors north, south and so on. The
hdelimiter i can be any delimiter that is acceptable to TEX’s \left command.
a8 a1 a6
a a a
3 5 7
a4 a9 a2
\begin{tikzpicture}
\matrix [matrix of math nodes,left delimiter=(,right delimiter=\}]
{
a_8 & a_1 & a_6 \\
a_3 & a_5 & a_7 \\
a_4 & a_9 & a_2 \\
};
\end{tikzpicture}
]
Z
)
1
x dx
0
\begin{tikzpicture}
\node [fill=red!20,left delimiter=(,right delimiter=\}]
{$\displaystyle\int_0^1 x\,dx$};
\end{tikzpicture}
]
(style, initially empty)
/tikz/every delimiter
This style is executed for every delimiter. You can use it to shift or color delimiters or do whatever.
(style, initially empty)
/tikz/every left delimiter
This style is additionally executed for every left delimiter.
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a8 a1 a6
a a a
3 5 7
a4 a9 a2
\begin{tikzpicture}
[every left delimiter/.style={red,xshift=1ex},
every right delimiter/.style={xshift=-1ex}]
\matrix [matrix of math nodes,left delimiter=(,right delimiter=\}]
{
a_8 & a_1 & a_6 \\
a_3 & a_5 & a_7 \\
a_4 & a_9 & a_2 \\
};
\end{tikzpicture}
]
/tikz/right delimiter=hdelimiter i
(no default)
Works as above.
(style, initially empty)
/tikz/every right delimiter
Works as above.
/tikz/above delimiter=hdelimiter i
(no default)
This option allows you to add a delimiter above the node. It is implemented by rotating a left delimiter.
a8 a1 a6
a3 a5 a7
a4 a9 a2
\begin{tikzpicture}
\matrix [matrix of math nodes,%
left delimiter=\|,right delimiter=\rmoustache,%
above delimiter=(,below delimiter=\}]
{
a_8 & a_1 & a_6 \\
a_3 & a_5 & a_7 \\
a_4 & a_9 & a_2 \\
};
\end{tikzpicture}
]
(style, initially empty)
/tikz/every above delimiter
Works as above.
/tikz/below delimiter=hdelimiter i
(no default)
Works as above.
(style, initially empty)
/tikz/every below delimiter
Works as above.
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58
Mindmap Drawing Library
Tik Z Library mindmap
\usetikzlibrary{mindmap} % LATEX and plain TEX
\usetikzlibrary[mindmap] % ConTEXt
This packages provides styles for drawing mindmap diagrams.
58.1
Overview
This library is intended to make the creation of mindmaps or concept maps easier. A mindmap is a graphical
representation of a concept together with related concepts and annotations. Mindmaps are, essentially, trees,
possibly with a few extra edges added, but they are usually drawn in a special way: The root concept is
placed in the middle of the page and is drawn as a huge circle, ellipse, or cloud. The related concepts then
“leave” this root concept via branch-like tendrils.
The mindmap library of Tik Z produces mindmaps that look a bit different from the standard mindmaps:
While the big root concept is still a circle, related concepts are also depicted as (smaller) circles. The related
concepts are linked to the root concept via organic-looking connections. The overall effect is visually rather
pleasing, but readers may not immediately think of a mindmap when they see a picture created with this
library.
Although it is not strictly necessary, you will usually create mindmaps using Tik Z’s tree mechanism
and some of the styles and macros of the package work best when used inside trees. However, it is still
possible and sometimes necessary to treat parts of a mindmap as a graph with arbitrary edges and this is
also possible.
58.2
The Mindmap Style
Every mindmap should be put in a scope or a picture where the mindmap style is used. This style installs
some internal settings.
(style, no value)
/tikz/mindmap
Use this style with all pictures or at least scopes that contain a mindmap. It installs a whole bunch of
settings that are useful for drawing mindmaps.
Root concept
Child concept
\tikz[mindmap,concept color=red!50]
\node [concept] {Root concept}
child[grow=right] {node[concept] {Child concept}};
The sizes of concepts are predefined in such a way that a medium-size mindmap will fit on an A4 page
(more or less).
(style, no value)
/tikz/every mindmap
This style is included by the mindmap style. Change this style to add special settings to your
mindmaps.
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Root concept
Child concept
\tikz[large mindmap,concept color=red!50]
\node [concept] {Root concept}
child[grow=right] {node[concept] {Child concept}};
Remark: Note that mindmap redefines font sizes and sibling angle depending on the current concept level (i.e. inside of level 1 concept, level 2 concept etc.). Thus, if you need to redefine these
variables, use
level 1 concept/.append style={font=\small}
or
level 2 concept/.append style={sibling distance=90}
after the mindmap style.
(style, no value)
/tikz/small mindmap
This style includes the mindmap style, but additionally changes the default size of concepts, fonts and
distances so that a medium-sized mindmap will fit on an A5 page (A5 pages are half as large as A4
pages). Mindmaps with small mindmap will also fit onto a standard frame of the beamer package.
(style, no value)
/tikz/large mindmap
This style includes the mindmap style, but additionally changes the default size of concepts, fonts and
distances so that a medium-sized mindmap will fit on an A3 page (A3 pages are twice as large as A4
pages).
(style, no value)
/tikz/huge mindmap
This style causes concepts to be even bigger and it is best used with A2 paper and above.
58.3
Concepts Nodes
The basic entities of mindmaps are called concepts in Tik Z. A concept is a node of style concept and it
must be circular for some of the connection macros to work.
58.3.1
Isolated Concepts
The following styles influence how isolated concepts are rendered:
(style, no value)
/tikz/concept
This style should be used with all nodes that are concepts, although some styles like extra concept
install this style automatically.
Basically, this style makes the concept node circular and installs a uniform color called concept color,
see below. Additionally, the style every concept is called.
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Some concept
\tikz[mindmap,concept color=red!50] \node [concept] {Some concept};
(style, no value)
/tikz/every concept
In order to change the appearance of concept nodes, you should change this style. Note, however,
that the color of a concept should be uniform for some of the connection bar stuff to work, so you
should not change the color or the draw/fill state of concepts using this option. It is mostly useful
for changing the text color and font.
/tikz/concept color=hcolor i
(no default)
This option tells Tik Z which color should be used for filling and stroking concepts. The difference
between this option and just setting every concept to the desired color is that this option allows
Tik Z to keep track of the colors used for concepts. This is important when you change the color
between two connected concepts. In this case, Tik Z can automatically create a shading that provides
a smooth transition between the old and the new concept color; we will come back to this in the
next section.
(style, no value)
/tikz/extra concept
This style is intended for concepts that are not part of the “mindmap tree,” but stand beside it. Typically,
they will have a subdued color or be smaller. In order to have these concepts appear in a uniform way
and in order to indicate in the code that these concepts are additional, you can use this style.
extra
concept
Root concept
\begin{tikzpicture}[mindmap,concept color=blue!80]
\node [concept]
{Root concept};
\node [extra concept] at (10,0) {extra concept};
\end{tikzpicture}
(style, no value)
/tikz/every extra concept
Change this style to change the appearance of extra concepts.
58.3.2
Concepts in Trees
As pointed out earlier, Tik Z assumes that your mindmap is built using the child facilities of Tik Z. There
are numerous options that influence how concepts are rendered at the different levels of a tree.
(style, no value)
/tikz/root concept
This style is used for the roots of mindmap trees. By adding something to this, you can change how
the root of a mindmap will be rendered.
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\tikz
[root concept/.append style={concept color=blue!80,minimum size=3.5cm},
mindmap]
\node [concept] {Root concept};
Root concept
Note that styles like large mindmap redefine these styles, so you should add something to this style
only inside the picture.
(style, no value)
/tikz/level 1 concept
The mindmap style adds this style to the level 1 style. This means that the first level children of a
mindmap tree will use this style.
child
Root concept
child
\tikz
[root concept/.append style={concept color=blue!80},
level 1 concept/.append style={concept color=red!50},
mindmap]
\node [concept] {Root concept}
child[grow=30] {node[concept] {child}}
child[grow=0 ] {node[concept] {child}};
(style, no value)
/tikz/level 2 concept
Works like level 1 concept, only for second level children.
(style, no value)
/tikz/level 3 concept
Works like level 1 concept.
(style, no value)
/tikz/level 4 concept
Works like level 1 concept. Note that there are no fifth and higher level styles, you need to modify
level 5 directly in such cases.
/tikz/concept color=hcolor i
(no default)
We saw already that this option is used to change the color of concepts. We now have a look at its effect
when used on child nodes of a concept. Normally, this option simply changes the color of the children.
However, when the option is given as an option to the child operation (and not to the node operation
and also not as an option to all children via the level 1 style), Tik Z will smoothly change the concept
color from the parent’s color to the color of the child concept.
Here is an example:
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Child concept
Root concept
Child concept
\tikz[mindmap,concept color=blue!80]
\node [concept] {Root concept}
child[concept color=red,grow=30] {node[concept] {Child concept}}
child[concept color=orange,grow=0] {node[concept] {Child concept}};
In order to have a concept color which changes with the hierarchy level, a tiny bit of magic is needed:
child
Root concept
child
\tikz[mindmap,text=white,
root concept/.style={concept color=blue},
level 1 concept/.append style=
{every child/.style={concept color=blue!50}}]
\node [concept] {Root concept}
child[grow=30] {node[concept] {child}}
child[grow=0 ] {node[concept] {child}};
58.4
58.4.1
Connecting Concepts
Simple Connections
The easiest way to connect two concepts is to draw a line between them. In order to give such lines a
consistent appearance, it is recommendable to use the following style when drawing such lines:
(style, no value)
/tikz/concept connection
This style can be used for lines between two concepts. Feel free to redefine this style.
A problem arises when you need to connect concepts after the main mindmap has been drawn. In this
case you will want the connection lines to lie behind the main mindmap. However, you can draw the lines
only after the coordinates of the concepts have been determined. In this case you should place the connecting
lines on a background layer as in the following example:
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child
Root concept
child
child
\begin{tikzpicture}
[root concept/.append style={concept color=blue!20,minimum size=2cm},
level 1 concept/.append style={sibling angle=45},
mindmap]
\node [concept] {Root concept}
[clockwise from=45]
child { node[concept] (c1) {child}}
child { node[concept] (c2) {child}}
child { node[concept] (c3) {child}};
\begin{pgfonlayer}{background}
\draw [concept connection] (c1) edge (c2)
edge (c3)
(c2) edge (c3);
\end{pgfonlayer}
\end{tikzpicture}
58.4.2
The Circle Connection Bar Decoration
Instead of a simple line between two concepts, you can also add a bar between the two nodes that has slightly
organic ends. These bars are also used by default as the edges from parents in the mindmap tree.
For the drawing of the bars a special decoration is used, which is defined in the mindmap library:
Decoration circle connection bar
This decoration can be used to connect two circles. The start of the to-be-decorated path should lie on
the border of the first circle, the end should lie on the border of the second circle. The following two
decoration keys should be initialized with the sizes of the circles:
• start radius
• end radius
Furthermore, the following two decoration keys influence the decoration:
• amplitude
• angle
The decoration turns a straight line into a path that starts on the border of the first circle at the
specified angle relative to the line connecting the centers of the circles. The path then changes into a
rectangle whose thickness is given by the amplitude. Finally, the path ends with the same angles on the
second circle.
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Here is an example that should make this clearer:
\begin{tikzpicture}
[decoration={start radius=1cm,end radius=.5cm,amplitude=2mm,angle=30}]
\fill[blue!20] (0,0) circle
(1cm);
\fill[red!20] (2.5,0) circle (.5cm);
\filldraw [draw=red,fill=black,
decorate,decoration=circle connection bar] (1,0) -- (2,0);
\end{tikzpicture}
As can be seen, the decorated path consists of three parts and is not really useful for drawing. However,
if you fill the decorated path only, and if you use the same color as for the circles, the result is better.
\begin{tikzpicture}
[blue!50,decoration={start radius=1cm,
end radius=.5cm,amplitude=2mm,angle=30}]
\fill (0,0) circle
(1cm);
\fill (2.5,0) circle (.5cm);
\fill [decorate,decoration=circle connection bar] (1,0) -- (2,0);
\end{tikzpicture}
In the above example you may notice the small white line between the circles and the decorated path.
This is due to rounding errors. Unfortunately, for larger distances, the errors can accumulate quite
strongly, especially since Tik Z and TEX are not very good at computing square roots. For this reason,
it is a good idea to make the circles slightly larger to cover up such problems. When using nodes of
shape circle, you can just add the draw option with a line width of one or two points (for very large
distances you may need line width up to 4pt).
\begin{tikzpicture}
[blue!50,decoration={start radius=1cm,
end radius=.5cm,amplitude=2mm,angle=30}]
\fill (0,0) circle
(1cm+1pt);
\fill (2.4,0) circle (.5cm+1pt);
\fill [decorate,decoration=circle connection bar] (1,0) -- (1.9,0);
\end{tikzpicture}
58.4.3
The Circle Connection Bar To-Path
The circle connection bar decoration is a bit complicated to use. Especially specifying the radii is quite
bothersome (the amplitude and the angle can be set once and for all). For this reason, the mindmap library
defines a special to-path that performs the necessary computations for you.
/tikz/circle connection bar
(style, no value)
This style installs a rather involved to-path. Unlike normal to-paths, this path requires that the start
and the target of the to-path are named nodes of shape circle – if this is not the case, this path will
produce errors.
Assuming that the start and the target are circles, the to-path will first compute the radii of these circles
(by measuring the distance from the center anchor to some anchor on the border) and will set the start
circle keys accordingly. Next, the fill option is set to the concept color while draw=none is set.
The decoration is set to circle connection bar. Finally, the following style is included:
(style, no value)
/tikz/every circle connection bar
Redefine this style to change the appearance of circle connection bar to-paths.
\begin{tikzpicture}[concept color=blue!50,blue!50,outer sep=0pt]
\node (n1) at (0,0)
[circle,minimum size=2cm,fill,draw,thick] {};
\node (n2) at (2.5,0) [circle,minimum size=1cm,fill,draw,thick] {};
\path (n1) to[circle connection bar] (n2);
\end{tikzpicture}
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Note that it is not a good idea to have more than one to operation together with the option
circle connection bar in a single \path. Use the edge operation, instead, for creating multiple
connections and this operation creates a new scope for each edge.
In a mindmap we sometimes want colors to change from one concept color to another. Then, the
connection bar should, ideally, consist of a smooth transition between these two colors. Getting this right
using shadings is a bit tricky if you try this “by hand,” so the mindmap library provides a special option for
facilitating this procedure.
/tikz/circle connection bar switch color=from(hfirst color i)to(hsecond color i)
(no default)
This style works similarly to the circle connection bar. The only difference is that instead of filling
the path with a single color a shading is used.
\begin{tikzpicture}[outer sep=0pt]
\node (n1) at (0,0)
[circle,minimum size=2cm,fill,draw,thick,red] {};
\node (n2) at (30:2.5) [circle,minimum size=1cm,fill,draw,thick,blue] {};
\path (n1) to[circle connection bar switch color=from (red) to (blue)] (n2);
\end{tikzpicture}
58.4.4
Tree Edges
Most of the time, concepts in a mindmap are connected automatically when the mindmap is built as a tree.
The reason is that the mindmap installs a circle connection bar path as the edge from parent path.
Also, the mindmap option takes care of things like setting the correct draw and outer sep settings and some
other stuff.
In detail, the mindmap option sets the edge from parent path to a path that uses the to-path
circle connection bar to connect the parent node and the child node. The concept color option (locally) changes this by using circle connection bar switch color instead with the from-color set to the
old (parent’s) concept color and the to-color set to the new (child’s) concept color. This means that when
you provide the concept color option to a child command, the color will change from the parent’s concept
color to the specified color.
Here is an example of a tree built in this way:
657
algorithms
data
structures
Computer Science
theoretical
practical
programming
languages
software
engineering
technical
applied
databases
WWW
\begin{tikzpicture}
\path[mindmap,concept color=black,text=white]
node[concept] {Computer Science}
[clockwise from=0]
% note that ‘sibling angle’ can only be defined in
% ‘level 1 concept/.append style={}’
child[concept color=green!50!black] {
node[concept] {practical}
[clockwise from=90]
child { node[concept] {algorithms} }
child { node[concept] {data structures} }
child { node[concept] {pro\-gramming languages} }
child { node[concept] {software engineer\-ing} }
}
child[concept color=blue] {
node[concept] {applied}
[clockwise from=-30]
child { node[concept] {databases} }
child { node[concept] {WWW} }
}
child[concept color=red] { node[concept] {technical} }
child[concept color=orange] { node[concept] {theoretical} };
\end{tikzpicture}
58.5
Adding Annotations
An annotation is some text outside a mindmap that, unlike an extra concept, simply explains something
in the mindmap. The following style is mainly intended to help readers of the code see that a node in an
annotation node.
(style, no value)
/tikz/annotation
This style indicates that a node is an annotation node. It includes the style every annotation, which
allows you to change this style in a convenient fashion.
658
Root concept
The root concept is, in general,
the most important concept.
\begin{tikzpicture}
[mindmap,concept color=blue!80,
every annotation/.style={fill=red!20}]
\node [concept] (root) {Root concept};
\node [annotation,right] at (root.east)
{The root concept is, in general, the most important concept.};
\end{tikzpicture}
(style, no value)
/tikz/every annotation
This style is included by annotation.
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59
Paper Folding Diagrams Library
Tik Z Library folding
\usetikzlibrary{folding} % LATEX and plain TEX
\usetikzlibrary[folding] % ConTEXt
This library defines pic types for creating paper folding diagrams. Many thanks to Nico van Cleemput
for providing most of the code.
Here is a big example that produces a diagram for a calendar:
5
6
01
r2
5 13
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b
4
2
m
0
ce
3 11 1 9 2 7
De 2
1
2
0
8
1
1
26
1
9
7
5
8 16 1 4 2
2
7 15
23 31
14 22 30
21 29
28
November 2015
1
2 3 4 5 6 7 8
9 10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25 26 27 28 29
30
Fe
br
ua
ry
3
9
20
15
4
16 10
1
23
7 11 1 5
6
2
24 18
1
7
25 19 13
8
26 20 14
27 21 15
28 22
5
201
ust
Aug
1 2 3 4
5 6 7 8 9 10 11
12 13 14 15 16 17 18
19 20 21 22 23 24 25
26 27 28 29 30 31
1 2 3 4 5 6 7
8 9 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26 27 28
29 30
June 2015
Ju
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6
2
1
13
01
7
5
2
8
20 14
3
9
21 15
2
7
28 22 16 10 1 4
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29 23 17
30 24 18 12
31 25 19
26
660
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9 17
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8
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4 22 2 0 3
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4 12 1 0 2 8 29
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25
1 2
8 9
6 7 15 16
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4
3 4 12 13 1 22 23
21
1
1
0
2
0
9 30
1
28 2
8 19
17 1 26 27
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24 2
31
January 2015
Apr
il 20
15
6 7 1 2
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4
1
20 2 15 16 0 11 1
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1 22
17 1
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7
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8 29 23 24 2 19
5 26
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Sep
tem
ber
201
1 2
5
7 8
3 4
9 10
14 1
5 6
5 16
11 1
21 2
2 13
17 1
2
28 2 23 24 8 19 2
0
9 30
25 2
6 27
2
015
1
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Mar
8
6 7 5
4 5 3 14 1
2 3 11 12 1 21 22
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9 10 18 19 2 28 29
7
7
26 2
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30 3
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5
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2
2
12 20 28
19 27
26
r
be
\sffamily\scriptsize
\tikz \pic [
transform shape,
every calendar/.style={
at={(-8ex,4ex)},
week list,
month label above centered,
month text=\bfseries\textcolor{red}{\%mt} \%y0,
if={(Sunday) [black!50]}
},
folding line length=2.5cm,
face 1={ \calendar [dates=\the\year-01-01 to \the\year-01-last];},
face 2={ \calendar [dates=\the\year-02-01 to \the\year-02-last];},
face 3={ \calendar [dates=\the\year-03-01 to \the\year-03-last];},
face 4={ \calendar [dates=\the\year-04-01 to \the\year-04-last];},
face 5={ \calendar [dates=\the\year-05-01 to \the\year-05-last];},
face 6={ \calendar [dates=\the\year-06-01 to \the\year-06-last];},
face 7={ \calendar [dates=\the\year-07-01 to \the\year-07-last];},
face 8={ \calendar [dates=\the\year-08-01 to \the\year-08-last];},
face 9={ \calendar [dates=\the\year-09-01 to \the\year-09-last];},
face 10={\calendar [dates=\the\year-10-01 to \the\year-10-last];},
face 11={\calendar [dates=\the\year-11-01 to \the\year-11-last];},
face 12={\calendar [dates=\the\year-12-01 to \the\year-12-last];}
] {dodecahedron folding};
The foldings are sorted by number of faces.
Pic type tetrahedron folding
This pic type draws a folding diagram for a tetrahedron. The following keys influence the pic:
(no default)
/tikz/folding line length=hdimensioni
Sets the length of the base line for folding. For the dodecahedron this is the length of all the sides
of the pentagons.
(no default)
/tikz/face 1=hcodei
The hcodei is executed for the first face of the dodecahedron. When it is executed, the coordinate
system will have been shifted and rotated such that it lies at the middle of the first face of the
dodecahedron.
(no default)
/tikz/face 2=hcodei
Same as face 1, but for the second face.
/tikz/face 3=hcodei
(no default)
/tikz/face 4=hcodei
(no default)
There are further similar options for more faces (for commands shown later).
1
2
4
Here is a simple example:
\tikz \pic [
transform shape,
folding line length=6mm,
face 1={ \node[red] {1};},
face 2={ \node
{2};},
face 3={ \node
{3};},
face 4={ \node
{4};}
] {tetrahedron folding};
3
The appearance of the cut and folding lines can be influenced using the following styles:
(style, initially empty)
/tikz/every cut
Executed for every line that should be cut using scissors.
(style, initially help lines)
/tikz/every fold
Executed for every line that should be folded.
661
\tikz \pic[
every cut/.style=red,
every fold/.style=dotted,
folding line length=6mm
] { tetrahedron folding };
There is one style that is mainly useful for the present documentation:
(style, no value)
/tikz/numbered faces
Sets face hi i to \node {hi i}; for all i.
Pic type tetrahedron truncated folding
A folding of a truncated tetrahedron.
\tikz \pic [folding line length=6mm, numbered faces, transform shape]
{ tetrahedron truncated folding };
3
8
2
4
6
1
7
5
Pic type cube folding
A folding of a cube.
\tikz \pic [folding line length=6mm, numbered faces, transform shape]
{ cube folding };
2
6
3
1
4
5
Pic type cube truncated folding
A folding of a truncated cube.
6
3
\tikz \pic [folding line length=6mm, numbered faces, transform shape]
{ cube truncated folding };
13
4
5
2
7
1
8
14
11
9
12
10
Pic type octahedron folding
A folding of an octahedron.
1
\tikz \pic [folding line length=6mm, numbered faces, transform shape]
{ octahedron folding };
4
3
2
6
8
7
5
662
Pic type octahedron folding
A folding of a truncated octahedron.
\tikz \pic [folding line length=6mm, numbered faces, transform shape]
{ octahedron truncated folding };
4
7
3
5
6
2
1
12
8
13
11
9
14
10
Pic type dodecahedron folding
A folding of a dodecahedron.
\tikz \pic [folding line length=6mm, numbered faces, transform shape]
{ dodecahedron folding };
12
11
3
2
10
9
8
4
1
6
5
7
Pic type dodecahedron’ folding
This is an alternative folding of a dodecahedron.
7
5
3
6
\tikz \pic [folding line length=6mm, numbered faces, transform shape]
{ dodecahedron’ folding };
4
2
11
12
10
1
8
9
Pic type cuboctahedron folding
A folding of a cuboctahedron.
663
\tikz \pic [folding line length=6mm, numbered faces, transform shape]
{ cuboctahedron folding };
5
4
7
11
14
6
2
1
3
13
12
9
8
10
Pic type cuboctahedron truncated folding
A folding of a truncated cuboctahedron.
10
7
11
9
4
8
13
3
12
26
2
14
1
22
15
16
20
21
19
17
18
25
24
23
6
5
\tikz \pic [folding line length=6mm, numbered faces, transform shape]
{ cuboctahedron truncated folding };
Pic type icosahedron folding
A folding of an icosahedron.
210
9
\tikz \pic [folding line length=6mm, numbered faces, transform shape]
{ icosahedron folding };
3
2
7
6
5
4
8
111
0
9 15
17
18
16
1
13
12
14
Pic type rhombicuboctahedron folding
A folding of an rhombicuboctahedron.
664
7
19 21 23 25 13 11 9
8 10 12 14 24 22 20
3
2
1
16
17
18
26
6
4
\tikz \pic [folding line length=6mm, numbered faces, transform shape]
{ rhombicuboctahedron folding };
15
5
Pic type snub cube folding
A folding of a snub cube.
8
10
25
24
23
22
29
21
18
9
5
4
11
3
38
37
35
\tikz \pic [folding line length=6mm, numbered faces, transform shape]
{ snub cube folding };
7
6
36 34
33
32
31
2
30
1
27
16
15
14
13
20
12
19
17
28
26
Pic type icosidodecahedron folding
A folding of an icosidodecahedron.
10
24
12
17 15
13
26
25
18
19
9
8
23
20
11
7
4
21
22
5
3
27 2
1
6
14
32
28
29
16
31
30
\tikz \pic [folding line length=6mm, numbered faces, transform shape]
{ icosidodecahedron folding };
665
60
Pattern Library
Tik Z Library patterns
\usepgflibrary{patterns}
\usepgflibrary[patterns]
\usetikzlibrary{patterns}
\usetikzlibrary[patterns]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
The package defines patterns for filling areas.
60.1
Form-Only Patterns
Pattern name
Example (pattern in black, blue, and red on faded checkerboard)
horizontal lines
vertical lines
north east lines
north west lines
grid
crosshatch
dots
crosshatch dots
fivepointed stars
sixpointed stars
bricks
checkerboard
60.2
Inherently Colored Patterns
Pattern name
Example
checkerboard light gray
horizontal lines light gray
horizontal lines gray
horizontal lines dark gray
horizontal lines light blue
horizontal lines dark blue
crosshatch dots gray
crosshatch dots light steel blue
666
61
Petri-Net Drawing Library
Tik Z Library petri
\usetikzlibrary{petri} % LATEX and plain TEX
\usetikzlibrary[petri] % ConTEXt
This packages provides shapes and styles for drawing Petri nets.
61.1
Places
The package defines a style for drawing places of Petri nets.
(style, no value)
/tikz/place
This style indicates that a node is a place of a Petri net. Usually, the text of the node should be empty
since places do not contain any text. You should use the label option to add text outside the node like
its name or its capacity. You should use the tokens options, explained in Section 61.3, to add tokens
inside the place.
\begin{tikzpicture}
\node[place,label=above:$p_1$,tokens=2]
(p1) {};
\node[place,label=below:$p_2\ge1$,right=of p1] (p2) {};
\end{tikzpicture}
p1
p2 ≥ 1
(style, no value)
/tikz/every place
This style is evoked by the style place. To change the appearance of places, you can change this
style.
p1
3
2 9
p2 ≥ 1
61.2
\begin{tikzpicture}
[every place/.style={draw=blue,fill=blue!20,thick,minimum size=9mm}]
\node[place,tokens=7,label=above:$p_1$] (p1) {};
\node[place,structured tokens={3,2,9},
label=below:$p_2\ge1$,right=of p1] (p2) {};
\end{tikzpicture}
Transitions
Transitions are also nodes. They should be drawn using the following style:
(style, no value)
/tikz/transition
This style indicates that a node is a transition. As for places, the text of a transition should be empty
and the label option should be used for adding labels.
To connect a transition to places, you can use the edge command as in the following example:
p1
p2 ≥ 1
\begin{tikzpicture}
\node[place,tokens=2,label=above:$p_1$]
(p1) {};
\node[place,label=above:$p_2\ge1$,right=of p1] (p2) {};
2
\node[transition,below right=of p1,label=below:$t_1$] {}
edge[pre]
(p1)
edge[post] node[auto] {2} (p2);
\end{tikzpicture}
t1
/tikz/every transition
This style is evoked by the style transition.
(style, no value)
/tikz/pre
(style, no value)
This style can be used with paths leading from a transition to a place to indicate that the place is
in the pre-set of the transition. By default, this style is <-,shorten <=1pt, but feel free to redefine
it.
667
(style, no value)
/tikz/post
This style is also used with paths leading from a transition to a place, but this time the place is in
the post-set of the transition. Again, feel free to redefine it.
(style, no value)
/tikz/pre and post
This style is to be used to indicate that a place is both in the pre- and post-set of a transition.
61.3
Tokens
Interestingly, the most complicated aspect of drawing Petri nets in Tik Z turns out to be the placement of
tokens.
Let us start with a single token. They are also nodes and there is a simple style for typesetting them.
(style, no value)
/tikz/token
This style indicates that a node is a token. By default, this causes the node to be a small black circle.
Unlike places and transitions, it does make sense to provide text for the token node. Such text will be
typeset in a tiny font and in white on black (naturally, you can easily change this by setting the style
every token).
p1
p2
y
\begin{tikzpicture}
\node[place,label=above:$p_1$]
\node[token] at (p1) {};
(p1) {};
\node[place,label=above:$p_2$,right=of p1] (p2) {};
\node[token] at (p2) {$y$};
\end{tikzpicture}
(style, no value)
/tikz/every token
Change this style to change the appearance of tokens.
In the above example, it is bothersome that we need an extra command for the token node. Worse, when
we have two tokens on a node, it is difficult to place both nodes inside the node without overlap.
The Petri net library offers a solution to this problem: The children are tokens style.
(style, no value)
/tikz/children are tokens
The idea behind this style is to use trees mechanism for placing tokens. Every token lying on a place is
treated as a child of the node. Normally this would have the effect that the tokens are placed below the
place and they would be connected to the place by an edge. The children are tokens style, however,
redefines the growth function of trees such that it places the children next to each other inside (or,
rather, on top) of the place node. Additionally, the edge from the parent node is not drawn.
p1
1
2 3
\begin{tikzpicture}
\node[place,label=above:$p_1$] {}
[children are tokens]
child {node [token] {1}}
child {node [token] {2}}
child {node [token] {3}};
\end{tikzpicture}
In detail, what happens is the following: Tree growth functions tell Tik Z where it should place the
children of nodes. These functions get passed the number of children that a node has an the number
of the child that should be placed. The special tree growth function for tokens has a special mapping
for each possible number of children up to nine children. This mapping decides for each child where
it should be placed on top of the place. For example, a single child is placed directly on top of the
place. Two children are placed next to each other, separated by the token distance. Three children
are placed in a triangle whose side lengths are token distance; and so on up to nine tokens. If you
wish to place more than nice tokens on a place, you will have to write your own placement code.
668
p2
1 2
2 1
\begin{tikzpicture}
\node[place,label=above:$p_2$] {}
[children are tokens]
child {node [token] {1}}
child {node [token,fill=red] {2}}
child {node [token,fill=red] {2}}
child {node [token] {1}};
\end{tikzpicture}
(no default)
/tikz/token distance=hdistancei
This specifies the distance between the centers of the tokens in the arrangements of the option
children are tokens.
p3
\begin{tikzpicture}
\node[place,label=above:$p_3$] {}
[children are tokens,token distance=1.1ex]
child {node [token] {}}
child {node [token,red] {}}
child {node [token,blue] {}}
child {node [token] {}};
\end{tikzpicture}
The children are tokens option gives you a lot of flexibility, but it is a bit cumbersome to use. For
this reason there are some options that help in standard situations. They all use children are tokens
internally, so any change to, say, the every token style will affect how these options depict tokens.
/tikz/tokens=hnumber i
(no default)
This option is given to a place node, not to a token node. The effect of this option is to add hnumber i
many child nodes to the place, each having the style token. Thus, the following two pieces of codes
have the same effect:
\tikz
\node[place] {}
[children are tokens]
child {node [token] {}}
child {node [token] {}}
child {node [token] {}};
\tikz
\node[place,tokens=3] {};
It is legal to say tokens=0, no tokens are drawn in this case. This option does not handle ten or more
tokens correctly. If you need this many tokens, you will have to program your own code.
\begin{tikzpicture}[every place/.style={minimum size=9mm}]
\foreach \x/\y/\tokennumber in {0/2/1,1/2/2,2/2/3,
0/1/4,1/1/5,2/1/6,
0/0/7,1/0/8,2/0/9}
\node [place,tokens=\tokennumber] at (\x,\y) {};
\end{tikzpicture}
/tikz/colored tokens=hcolor listi
(no default)
This option, which must also be given when a place node is being created, gets a list of colors as
parameter. It will then add as many tokens to the place as there are colors in this list, each filled
correspondingly.
\tikz
\node[place,colored tokens={black,black,red,blue}] {};
/tikz/structured tokens=htoken textsi
(no default)
669
This option, which must again be passed to a place, gets a list of texts for tokens. For each text, a new
token will be added to the place.
x
y z
\tikz
\node[place,structured tokens={$x$,$y$,$z$}] {};
\begin{tikzpicture}[every place/.style={minimum size=9mm}]
1
1 2
1
2 3
1 2
3 4
1
2 3
4 5
1 2 3
4 5 6
1
2
4
3
5
7
6
1 2
3 4 5
6 7 8
1 2 3
4 5 6
7 8 9
\foreach \x/\y/\tokennumber in {0/2/1,1/2/2,2/2/3,
0/1/4,1/1/5,2/1/6,
0/0/7,1/0/8,2/0/9}
\node [place,structured tokens={1,...,\tokennumber}] at (\x,\y) {};
\end{tikzpicture}
If you use lots of structured tokens, consider redefining the every token style so that the tokens are
larger.
61.4
Examples
p1
p2
p3
p4
q1
m1 = f
m2 = f
m1 = t
m2 = t
q2
q3
q4
hold = 1
p5
q5
hold = 2
p6
q6
670
\begin{tikzpicture}[yscale=-1.6,xscale=1.5,thick,
every transition/.style={draw=red,fill=red!20,minimum size=3mm},
every place/.style={draw=blue,fill=blue!20,minimum size=6mm}]
\foreach \i in {1,...,6} {
\node[place,label=left:$p_\i$] (p\i) at (0,\i) {};
\node[place,label=right:$q_\i$] (q\i) at (8,\i) {};
}
\foreach \name/\var/\vala/\valb/\height/\x in
{m1/m_1/f/t/2.25/3,m2/m_2/f/t/2.25/5,h/\mathit{hold}/1/2/4.5/4} {
\node[place,label=above:{$\var = \vala$}] (\name\vala) at (\x,\height) {};
\node[place,yshift=-8mm,label=below:{$\var = \valb$}] (\name\valb) at (\x,\height) {};
}
\node[token] at (p1) {};
\node[token] at (q1) {};
\node[token] at (m1f) {}; \node[token] at (m2f) {};
\node[token] at (h1) {};
\node[transition] at (1.5,1.5) {}
\node[transition] at (1.5,2.5) {}
\node[transition] at (1.5,3.3) {}
\node[transition] at (1.5,3.7) {}
\node[transition] at (1.5,4.3) {}
\node[transition] at (1.5,4.7) {}
\node[transition] at (1.5,5.5) {}
\node[transition] at (1.5,6.5) {}
\node[transition] at (6.5,1.5) {}
\node[transition] at (6.5,2.5) {}
\node[transition] at (6.5,3.3) {}
\node[transition] at (6.5,3.7) {}
\node[transition] at (6.5,4.3) {}
\node[transition] at (6.5,4.7) {}
\node[transition] at (6.5,5.5) {}
\node[transition] at (6.5,6.5) {}
\end{tikzpicture}
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
edge
[pre] (p1) edge [post] (p2);
[pre] (p2) edge[pre]
(m1f)
[post](p3) edge[post] (m1t);
[pre] (p3) edge [post] (p4)
[pre and post] (h1);
[pre] (p3) edge [pre] (h2)
[post] (p4) edge [post] (h1.west);
[pre] (p4) edge [post] (p5)
[pre and post] (m2f);
[pre] (p4) edge [post] (p5)
[pre and post] (h2);
[pre] (p5) edge [pre] (m1t)
[post] (p6) edge [post] (m1f);
[pre] (p6) edge [post] (p1.south east);
[pre] (q1) edge [post] (q2);
[pre] (q2) edge [pre] (m2f)
[post] (q3) edge [post] (m2t);
[pre] (q3) edge [post] (q4)
[pre and post] (h2);
[pre] (q3) edge [pre] (h1)
[post] (q4) edge [post] (h2.east);
[pre] (q4) edge [post] (q5)
[pre and post] (m1f);
[pre] (q4) edge [post] (q5)
[pre and post] (h1);
[pre] (q5) edge [pre] (m2t)
[post] (q6) edge [post] (m2f);
[pre] (q6) edge [post] (q1.south west);
Here is the same net once more, but with these styles changes:
\begin{tikzpicture}[yscale=-1.1,thin,>=stealth,
every transition/.style={fill,minimum width=1mm,minimum height=3.5mm},
every place/.style={draw,thick,minimum size=6mm}]
p1
p2
q1
m1 = f
m2 = f
q2
p3
q3
m1 = t
p4
m2 = t
q4
hold = 1
p5
p6
q5
hold = 2
q6
671
62
Plot Handler Library
Tik Z Library plothandlers
\usepgflibrary{plothandlers}
\usepgflibrary[plothandlers]
\usetikzlibrary{plothandlers}
\usetikzlibrary[plothandlers]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library packages defines additional plot handlers, see Section 107.3 for an introduction to plot
handlers. The additional handlers are described in the following.
This library is loaded automatically by Tik Z.
62.1
Curve Plot Handlers
\pgfplothandlercurveto
This handler will issue a \pgfpathcurveto command for each point of the plot, except possibly
for the first. As for the line-to handler, what happens with the first point can be specified using
\pgfsetmovetofirstplotpoint or \pgfsetlinetofirstplotpoint.
Obviously, the \pgfpathcurveto command needs, in addition to the points on the path, some control
points. These are generated automatically using a somewhat “dumb” algorithm: Suppose you have three
points x, y, and z on the curve such that y is between x and z:
y
z
x
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfplothandlercurveto
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
In order to determine the control points of the curve at the point y, the handler computes the vector
z − x and scales it by the tension factor (see below). Let us call the resulting vector s. Then y + s and
y − s will be the control points around y. The first control point at the beginning of the curve will be
the beginning itself, once more; likewise the last control point is the end itself.
\pgfsetplottension{hvaluei}
Sets the factor used by the curve plot handlers to determine the distance of the control points from
the points they control. The higher the curvature of the curve points, the higher this value should be.
A value of 1 will cause four points at quarter positions of a circle to be connected using a circle. The
default is 0.5.
y
z
x
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfsetplottension{0.75}
\pgfplothandlercurveto
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
\pgfplothandlerclosedcurve
This handler works like the curve-to plot handler, only it will add a new part to the current path that
is a closed curve through the plot points.
672
y
z
x
62.2
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfplothandlerclosedcurve
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
Constant Plot Handlers
There are several plot handlers which produce piecewise constant interpolations between successive points:
\pgfplothandlerconstantlineto
This handler works like the line-to plot handler, only it will produce a connected, piecewise constant
path to connect the points.
y
z
x
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfplothandlerconstantlineto
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
\pgfplothandlerconstantlinetomarkright
A variant of \pgfplothandlerconstantlineto which places its mark on the right line ends.
y
z
x
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfplothandlerconstantlinetomarkright
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
\pgfplothandlerconstantlinetomarkmid
A variant of \pgfplothandlerconstantlineto which places its mark on the center of the line.
y
z
x
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfplothandlerconstantlinetomarkmid
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
The plot handler always connects two data points by a horizontal line starting from the previous data
points, followed by a vertical line in the middle between the two data points, followed by a horizontal
line between the middle and the current data point. This results in a symmetric constant plot handler
for constant mesh width.
\pgfplothandlerjumpmarkleft
This handler works like the line-to plot handler, only it will produce a non-connected, piecewise constant
path to connect the points. If there are any plot marks, they will be placed on the left open pieces.
673
y
z
x
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfplothandlerjumpmarkleft
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
\pgfplothandlerjumpmarkright
This handler works like the line-to plot handler, only it will produce a non-connected, piecewise constant
path to connect the points. If there are any plot marks, they will be placed on the right open pieces.
y
z
x
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfplothandlerjumpmarkright
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
\pgfplothandlerjumpmarkmid
This handler works like the \pgfplothandlerconstantlinetomarkmid, but it will produce a nonconnected, piecewise constant path to connect the points. If there are any plot marks, they will be
placed in the center of the horizontal line segment..
y
z
x
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfplothandlerjumpmarkmid
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
See \pgfplothandlerconstantlinetomarkmid for details.
62.3
Comb Plot Handlers
There are three “comb” plot handlers. Their name stems from the fact that the plots they produce look like
“combs” (more or less).
\pgfplothandlerxcomb
This handler converts each point in the plot stream into a line from the y-axis to the point’s coordinate,
resulting in a “horizontal comb.”
y
z
x
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfplothandlerxcomb
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
674
\pgfplothandlerycomb
This handler converts each point in the plot stream into a line from the x-axis to the point’s coordinate,
resulting in a “vertical comb.”
This handler is useful for creating “bar diagrams.”
y
z
x
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfplothandlerycomb
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
\pgfplothandlerpolarcomb
This handler converts each point in the plot stream into a line from the origin to the point’s coordinate.
y
z
x
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfplothandlerpolarcomb
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
pgf bar or comb plots usually draw something from zero to the current plot’s coordinate. The “zero”
offset can be changed using an input stream which returns the desired offset successively for each processed
coordinate.
There are two such streams, which can be configured independently. The first one returns “zeros” for
coordinate x, the second one returns “zeros” for coordinate y. They are used as follows.
\pgfplotxzerolevelstreamstart
\pgfplotxzerolevelstreamnext % assigns \pgf@x
\pgfplotxzerolevelstreamnext
\pgfplotxzerolevelstreamnext
\pgfplotxzerolevelstreamend
\pgfplotyzerolevelstreamstart
\pgfplotyzerolevelstreamnext % assigns \pgf@x
\pgfplotyzerolevelstreamend
Different zero level streams can be implemented by overwriting these macros.
\pgfplotxzerolevelstreamconstant{hdimensioni}
This zero level stream always returns {hdimensioni} instead of x = 0pt.
It is used for xcomb and xbar.
\pgfplotyzerolevelstreamconstant{hdimensioni}
This zero level stream always returns {hdimensioni} instead of y = 0pt.
It is used for ycomb and ybar.
62.4
Bar Plot Handlers
While comb plot handlers produce a line-to operation to generate combs, bar plot handlers employ rectangular shapes, allowing filled bars (or pattern bars).
\pgfplothandlerybar
675
This handler converts each point in the plot stream into a rectangle from the x-axis to the point’s
coordinate. The rectangle is placed centered at the x-axis.
y
z
x
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfplothandlerybar
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
\pgfplothandlerxbar
This handler converts each point in the plot stream into a rectangle from the y-axis to the point’s
coordinate. The rectangle is placed centered at the y-axis.
y
z
x
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfplothandlerxbar
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
(no default, initially 10pt)
/pgf/bar width={hdimensioni}
alias /tikz/bar width
Sets the width of \pgfplothandlerxbar and \pgfplothandlerybar to {hdimensioni}. The argument
{hdimensioni} will be evaluated using the math parser.
(no default, initially 0pt)
/pgf/bar shift={hdimensioni}
alias /tikz/bar shift
Sets a shift used by \pgfplothandlerxbar and \pgfplothandlerybar to {hdimensioni}. It has the
same effect as xshift, but it applies only to those bar plots. The argument {hdimensioni} will be
evaluated using the math parser.
\pgfplotbarwidth
Expands to the value of /pgf/bar width.
\pgfplothandlerybarinterval
This handler is a variant of \pgfplothandlerybar which works with intervals instead of points.
Bars are drawn between successive input coordinates and the width is determined relatively to the
interval length.
x1
x2
x3
x4
\begin{tikzpicture}
\draw[gray] (0,2) node {$x_1$} (1,1) node {$x_2$} (2,.5) node {$x_3$} (4,0.7) node {$x_4$};
\pgfplothandlerybarinterval
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{2cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreampoint{\pgfpoint{4cm}{0.7cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
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In more detail, if (xi , yi ) and (xi+1 , yi+1 ) denote successive input coordinates, the bar will be placed
above the interval [xi , xi+1 ], centered at
xi + hbar interval shifti · (xi+1 − xi )
with width
hbar interval widthi · (xi+1 − xi ).
Here, hbar interval shifti and hbar interval widthi denote the current values of the associated options.
If you have N + 1 input points, you will get N bars (one for each interval). The y value of the last point
will be ignored.
\pgfplothandlerxbarinterval
As \pgfplothandlerybarinterval, this handler provides bar plots with relative bar sizes and offsets,
one bar for each y coordinate interval.
/pgf/bar interval shift={hfactor i}
(no default, initially 0.5)
alias /tikz/bar interval shift
Sets the relative shift of \pgfplothandlerxbarinterval and \pgfplothandlerybarinterval to
hfactor i. As /pgf/bar interval width, the argument is relative to the interval length of the input
coordinates.
The argument {hscalei} will be evaluated using the math parser.
(no default, initially 1)
/pgf/bar interval width={hscalei}
alias /tikz/bar interval width
Sets the relative width of \pgfplothandlerxbarinterval and \pgfplothandlerybarinterval to
{hscalei}. The argument is relative to (xi+1 − xi ) for y bar plots and relative to (yi+1 − yi ) for x bar
plots.
The argument {hscalei} will be evaluated using the math parser.
\begin{tikzpicture}[bar interval width=0.5]
\draw[gray]
(0,3) -- (0,-0.1)
(1,3) -- (1,-0.1)
(2,3) -- (2,-0.1)
(4,3) -- (4,-0.1);
\pgfplothandlerybarinterval
\begin{scope}[bar interval shift=0.25,fill=blue]
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{2cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreampoint{\pgfpoint{4cm}{0.7cm}}
\pgfplotstreamend
\pgfusepath{fill}
\end{scope}
\begin{scope}[bar interval shift=0.75,fill=red]
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{3cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{0.2cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.7cm}}
\pgfplotstreampoint{\pgfpoint{4cm}{0.2cm}}
\pgfplotstreamend
\pgfusepath{fill}
\end{scope}
\end{tikzpicture}
Please note that bars are always centered, so we have to use shifts 0.25 and 0.75 instead of 0 and 0.5.
62.5
Gapped Plot Handlers
\pgfplothandlergaplineto
This handler will connect the points of the plots by straight line segments. However, at the start and
the end of the lines there will be a small gap, given by the following key:
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/pgf/gap around stream point=hdimensioni
(no default, initially 1.5pt)
The hdimensioni by which the lines between consecutive stream points are shortened at the beginning and end.
\begin{tikzpicture}
\pgfplothandlergaplineto
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
\pgfplothandlergapcycle
Works like \pgfplothandlergaplineto, but the last point is connected to the first in the same fashion:
\begin{tikzpicture}
\pgfplothandlergapcycle
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
62.6
Mark Plot Handler
\pgfplothandlermark{hmark codei}
This command will execute the hmark codei for some points of the plot, but each time the coordinate
transformation matrix will be set up such that the origin is at the position of the point to be plotted.
This way, if the hmark codei draws a little circle around the origin, little circles will be drawn at some
point of the plot.
By default, a mark is drawn at all points of the plot. However, two parameters r and p influence this.
First, only every rth mark is drawn. Second, the first mark drawn is the pth. These parameters can be
influenced using the commands below.
y
z
x
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfplothandlermark{\pgfpathcircle{\pgfpointorigin}{4pt}\pgfusepath{stroke}}
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
Typically, the hcodei will be \pgfuseplotmark{hplot mark namei}, where hplot mark namei is the name
of a predefined plot mark.
\pgfsetplotmarkrepeat{hrepeati}
Sets the r parameter to hrepeati, that is, only every rth mark will be drawn.
\pgfsetplotmarkphase{hphasei}
Sets the p parameter to hphasei, that is, the first mark to be drawn is the pth, followed by the (p + r)th,
then the (p + 2r)th, and so on.
\pgfplothandlermarklisted{hmark codei}{hindex listi}
This command works similar to the previous one. However, marks will only be placed at those indices
in the given hindex listi. The syntax for the list is the same as for the \foreach statement. For
678
example, if you provide the list 1,3,...,25, a mark will be placed only at every second point. Similarly,
1,2,4,8,16,32 yields marks only at those points that are powers of two.
y
z
x
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfplothandlermarklisted
{\pgfpathcircle{\pgfpointorigin}{4pt}\pgfusepath{stroke}}
{1,3}
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
\pgfuseplotmark{hplot mark namei}
Draws the given hplot mark namei at the origin. The hplot mark namei must have been previously
declared using \pgfdeclareplotmark.
y
z
x
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfplothandlermark{\pgfuseplotmark{pentagon}}
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
\pgfdeclareplotmark{hplot mark namei}{hcodei}
Declares a plot mark for later used with the \pgfuseplotmark command.
y
z
x
\pgfdeclareplotmark{my plot mark}
{\pgfpathcircle{\pgfpoint{0cm}{1ex}}{1ex}\pgfusepathqstroke}
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfplothandlermark{\pgfuseplotmark{my plot mark}}
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
\pgfsetplotmarksize{hdimensioni}
This command sets the TEX dimension \pgfplotmarksize to hdimensioni. This dimension is a “recommendation” for plot mark code at which size the plot mark should be drawn; plot mark code may
choose to ignore this hdimensioni altogether. For circles, hdimensioni should be the radius, for other
shapes it should be about half the width/height.
The predefined plot marks all take this dimension into account.
y
z
x
\begin{tikzpicture}
\draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
\pgfsetplotmarksize{1ex}
\pgfplothandlermark{\pgfuseplotmark{*}}
\pgfplotstreamstart
\pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
\pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
\pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
\pgfplotstreamend
\pgfusepath{stroke}
\end{tikzpicture}
679
\pgfplotmarksize
A TEX dimension that is a “recommendation” for the size of plot marks.
The following plot marks are predefined (the filling color has been set to yellow):
\pgfuseplotmark{*}
\pgfuseplotmark{x}
\pgfuseplotmark{+}
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63
Plot Mark Library
Tik Z Library plotmarks
\usepgflibrary{plotmarks}
\usepgflibrary[plotmarks]
\usetikzlibrary{plotmarks}
\usetikzlibrary[plotmarks]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library defines a number of plot marks.
This library defines the following plot marks in addition to *, x, and + (the filling color has been set to
a dark yellow):
\pgfuseplotmark{-}
\pgfuseplotmark{|}
\pgfuseplotmark{o}
\pgfuseplotmark{asterisk}
\pgfuseplotmark{star}
\pgfuseplotmark{10-pointed star}
\pgfuseplotmark{oplus}
\pgfuseplotmark{oplus*}
\pgfuseplotmark{otimes}
\pgfuseplotmark{otimes*}
\pgfuseplotmark{square}
\pgfuseplotmark{square*}
\pgfuseplotmark{triangle}
\pgfuseplotmark{triangle*}
\pgfuseplotmark{diamond}
\pgfuseplotmark{diamond*}
\pgfuseplotmark{halfdiamond*}
\pgfuseplotmark{halfsquare*}
\pgfuseplotmark{halfsquare right*}
\pgfuseplotmark{halfsquare left*}
\pgfuseplotmark{pentagon}
\pgfuseplotmark{pentagon*}
\pgfuseplotmark{Mercedes star}
\pgfuseplotmark{Mercedes star flipped}
\pgfuseplotmark{halfcircle}
\pgfuseplotmark{halfcircle*}
\pgfuseplotmark{heart}
p
p
\pgfuseplotmark{text}
p
p
Note that each of the provided marks can be rotated freely by means of mark options={rotate=90} or
every mark/.append style={rotate=90}.
/pgf/mark color={hcolor i}
(no default, initially empty)
Defines the additional fill color for the halfcircle, halfcircle*, halfdiamond* and halfsquare*
markers. An empty value uses white (which is the initial configuration). The special value none
disables filling of the respective parts.
Note that halfsquare will be filled with mark color, and the starred variant halfsquare* will be filled
half with mark color and half with the actual fill color.
(no default, initially p)
/pgf/text mark={htexti}
Changes the text shown by mark=text.
m
m
With /pgf/text mark=m: m
m
A
A
With /pgf/text mark=A: A
A
There is no limitation about the number of characters or whatever. In fact, any TEX material can be
inserted as {htexti}, including images.
681
(no default, initially false)
/pgf/text mark as node={hbooleani}
Configures how mark=text will be drawn: either as \node or as \pgftext.
The first choice is highly flexible and possibly slow, the second is very fast and usually enough.
/pgf/text mark style={hoptions for mark=text i}
(no default)
Defines a set of options which control the appearance of mark=text.
If /pgf/text mark as node=false (the default), {hoptionsi} is provided as argument to \pgftext –
which provides only some basic keys like left, right, top, bottom, base and rotate.
If /pgf/text mark as node=true, {hoptionsi} is provided as argument to \node. This means you can
provide a very powerful set of options including anchor, scale, fill, draw, rounded corners etc.
682
64
Profiler Library
by Christian Feuersänger
Tik Z Library profiler
\usepgflibrary{profiler}
\usepgflibrary[profiler]
\usetikzlibrary{profiler}
\usetikzlibrary[profiler]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
A library to simplify the optimization of runtime speed of TEX programs.
It relies on the pdftex primitive \pdfelapsedtime11 to count (fractional) seconds and counts total time
and self time for macro invocations.
64.1
Overview
The intended audience for this library are people writing TEX code which should be optimized. It is certainly
not useful for the end-user.
The work flow for the optimization is simple: the preamble contains configuration commands like
\usepgflibrary{profiler}
\pgfprofilenewforenvironment{tikzpicture}
\pgfprofilenewforcommand{\pgfkeys}1}
and then, the time between \begin{tikzpicture} and \end{tikzpicture} and the time required to call
\pgfkeys will be collected.
At the end, a short usage summary like
pgflibraryprofiler(main job) {total time=1.07378sec; (100.0122%) self time=0.034sec; (3.1662%)}
pgflibraryprofiler(tikzpicture) {total time=1.03978sec; (96.84601%) self time=1.00415sec; (93.52722%)}
pgflibraryprofiler(pgfkeys) {total time=0.03563sec; (3.31726%) self time=0.03563sec; (3.31726%)}
will be provided in the log file, furthermore, the same information is available in a text table called
\jobname.profiler.hdatetimei.dat which is of the form:
profilerentry
main job
tikzpicture
pgfkeys
totaltime[s]
1.07378
1.03978
0.03563
totaltime[percent]
100.0122
96.84601
3.31726
selftime[s]
0.034
1.00415
0.03563
selftime[percent]
3.1662
93.52722
3.31726
Here, the totaltime means the time used for all invocations of the respective profiler entry (one row in
the table). The selftime measures time which is not already counted for in another profiler entry which
has been invoked within the current one. The example above is not very exciting: the main job consists only
of several (quite complex) pictures and nothing else. Thus, its total time is large. However, the self time is
very small because the tikzpictures are counted separately, and they have been invoked within the main
job. The \pgfkeys control sequence has been invoked within the tikzpicture, that’s why the selftime
for the tikzpicture is a little bit smaller than its totaltime.
64.2
Requirements
The library works with pdftex and luatex. Furthermore, it requires a more or less recent version of pdftex
which supports the \pdfelapsedtime directive.
64.3
Defining Profiler Entries
Unlike profilers for C/C++ or java, this library doesn’t extract information about every TEX macro automatically, nor does it collect information for each of them. Instead, every profiler entry needs to be defined
explicitly. Only defined profiler entries will be processed.
\pgfprofilenew{hnamei}
Defines a new profiler entry named hnamei.
11 The
primitive is emulated in luaTEX.
683
This updates a set of internal registers used to track the profiler entry. The hnamei can be arbitrary, it
doesn’t need to be related to any TEX macro.
The actual job of counting seconds is accomplished using \pgfprofilestart{hnamei} followed eventually by the command \pgfprofileend{hnamei}.
It doesn’t hurt if \pgfprofilenew is called multiple times with the same name.
\pgfprofilenewforcommand[hprofiler entry namei]{h\macroi}{hargumentsi}
Defines a new profiler entry which will measure the time spent in h\macroi. This calls \pgfprofilenew
and replaces the current definition of h\macroi with a new one.
If [hprofiler entry namei] has been provided, this defines the argument for \pgfprofilenew. It is
allowed to use the same name for multiple commands; in this case, they are treated as if it where the same
command. If the optional argument is not used, the profiler entry will be called ‘\pgfprofilecshmacroi’
(hmacroi without backslash) where \pgfprofilecs is predefined to be .
The replacement macro will collect all required arguments, start counting, invoke the original macro
definition and stop counting.
The following macro types are supported within \pgfprofilenewforcommand:
• commands which take one (optional) argument in square brackets followed by one optional argument which has to be delimited by curly braces (use an empty argument for hargumentsi in this
case),
• commands which take one (optional) argument in square brackets and exactly hargumentsi arguments afterwards.
Take a look at \pgfprofilenewforcommandpattern in case you have more complicated commands.
Note that the library can’t detect if a command has been redefined somewhere.
\pgfprofilenewforcommandpattern[hprofiler entry namei]{h\macroi}{hargument patterni}{hinvocation
patterni}
A variant of \pgfprofilenewforcommand which can be used with arbitrary hargument patternsi. Example:
\def\mymacro#1\to#2\in#3{ ... }
\pgfprofilenewforcommandpattern{\mymacro}{#1\to#2\in#3}{{#1}\to{#2}\in{#3}}
Note that \pgfprofilenewforcommand is a special case of \pgfprofilenewforcommandpattern:
\def\mymacro#1#2{ ... }
\pgfprofilenewforcommand\macro{2}
\pgfprofilenewforcommandpattern{\mymacro}{#1#2}{{#1}{#2}}
Thus, hargument patterni is a copy-paste from the definition of your command. The hinvocation patterni
is used by the profiler library to invoke the original command, so it is closely related to hargument
patterni, but it needs extra curly braces around each argument.
The behavior of \pgfprofilenewforcommandpattern is the same as discussed above: it defines a new
profiler entry which will measure the time spent in h\macroi. The details about this definition has
already been described. Note that up to one optional argument in square brackets is also checked
automatically.
If you like to profile a command which doesn’t match here for whatever reasons, you’ll have to redefine
it manually and insert \pgfprofilestart and \pgfprofileend in appropriate places.
\pgfprofileshowinvocationsfor{hprofiler entry namei}
Enables verbose output for every invocation of hprofiler entry namei.
This is only available for profiler entries for commands (those created by \pgfprofilenewforcommand
for example). It will also show all given arguments.
\pgfprofileshowinvocationsexpandedfor{hprofiler entry namei}
A variant of \pgfprofileshowinvocationsfor which will expand all arguments for hprofiler entry
namei before showing them. The invocation as such is not affected by this expansion.
This expansion (with \edef) might yield unrecoverable errors for some commands. Handle with care.
684
\pgfprofilenewforenvironment[hprofiler entry namei]{henvironment namei}
Defines a new profiler entry which measures time spent in the environment henvironment namei.
This calls \pgfprofilenew and handles the begin/end of the environment automatically.
The argument for \pgfprofilenew is hprofiler entry namei, or, if this optional argument is not used,
it is ‘\pgfprofileenvhenvironment namei’ where \pgfprofileenv is predefined as . Again, it is
permitted to use the same hprofiler entry namei multiple times to merge different commands into one
output section.
\pgfprofilestart{hprofiler entry namei}
Starts (or resumes) timing of hprofiler entry namei. The argument must have been declared in the
preamble using \pgfprofilenew.
Nested calls of \pgfprofilestart with the same argument will be ignored.
The invocation of this command doesn’t change the environment: it doesn’t introduce any TEX groups
nor does it modify the token list.
\pgfprofileend{hprofiler entry namei}
Stops (or interrupts) timing of hprofiler entry namei.
This command finishes a preceding call to \pgfprofilestart.
\pgfprofilepostprocess
For LATEX, this command is installed automatically in \end{document}. It stops all running timings,
evaluates them and returns the result into the logfile. Furthermore, it generates a text table called
\jobname.profiler.hYYYY i-hMM i-hDDi_hHH ih_hMM im.dat with the same information.
Note that the profiler library predefines two profiler entries, namely main job which counts time from
the beginning of the document until \pgfprofilepostprocess and preamble which counts time from
the beginning of the document until \begin{document}.
\pgfprofilesetrel{hprofiler entry namei} (initially main job)
Sets the profiler entry whose total time will be used to compute all other relative times. Thus, hprofiler
entry namei will use 100% of the total time per definition, all other relative times are relative to this
one.
\pgfprofileifisrunning{hprofiler entry namei}{htrue codei}{hfalse codei}
Invokes {htrue codei} if {hprofiler entry namei} is currently running and {hfalse codei} otherwise.
685
65
Shadings Library
Tik Z Library shadings
\usepgflibrary{shadings}
\usepgflibrary[shadings]
\usetikzlibrary{shadings}
\usetikzlibrary[shadings]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
The package defines a number of shadings in addition to the ball and axis shadings that are available
by default.
In the following, the shadings defined in the library are listed in alphabetical order. The colors of some
of these shadings can be configured using special options (like left color). These options implicitly select
the shading.
The three shadings axis, ball, and radial are always defined, even when this library is not used.
Shading axis
In this always-defined shading the colors change gradually between three horizontal lines. The top line
is at the top (uppermost) point of the path, the middle is in the middle, the bottom line is at the bottom
of the path.
/tikz/top color=hcolor i
(no default)
This option sets the color to be used at the top in an axis shading. When this option is given,
several things happen:
1. The shade option is selected.
2. The shading=axis option is selected.
3. The middle color of the axis shading is set to the average of the given top color hcolor i and of
whatever color is currently selected for the bottom.
4. The rotation angle of the shading is set to 0.
\tikz \draw[top color=red] (0,0) rectangle (2,1);
/tikz/bottom color=hcolor i
(no default)
This option works like top color, only for the bottom color.
/tikz/middle color=hcolor i
(no default)
This option specifies the color for the middle of an axis shading. It also sets the shade and
shading=axis options, but it does not change the rotation angle.
Note: Since both top color and bottom color change the middle color, this option should be
given last if all of these options need to be given:
\tikz \draw[top color=white,bottom color=black,middle color=red]
(0,0) rectangle (2,1);
/tikz/left color=hcolor i
(no default)
This option does exactly the same as top color, except that the shading angle is set to 90◦ .
/tikz/right color=hcolor i
(no default)
Works like left color.
Shading ball
This always-defined shading fills the path with a shading that “looks like a ball.” The default “color” of
the ball is blue (for no particular reason).
686
/tikz/ball color=hcolor i
(no default)
This option sets the color used for the ball shading. It sets the shade and shading=ball options.
Note that the ball will never “completely” have the color hcolor i. At its “highlight” spot a certain
amount of white is mixed in, at the border a certain amount of black. Because of this, it also makes
sense to say ball color=white or ball color=black
\begin{tikzpicture}
\shade[ball color=white] (0,0) circle (2ex);
\shade[ball color=red] (1,0) circle (2ex);
\shade[ball color=black] (2,0) circle (2ex);
\end{tikzpicture}
Shading bilinear interpolation
This shading fills a rectangle with colors that a bilinearly interpolated between the colors in the four
corners of the rectangle. These four colors are called lower left, lower right, upper left, and
upper right. By changing these color, you can change the way the shading looks. The library also
defines four options, called the same way, that can be used to set these colors and select the shading
implicitly.
\tikz
\shade[upper left=red,upper right=green,
lower left=blue,lower right=yellow]
(0,0) rectangle (3,2);
/tikz/lower left=hcolor i
(no default, initially white)
Sets the color to be used in a bilinear interpolation shading for the lower left corner. Also,
this options selects this shading and sets the shade option.
/tikz/upper left=hcolor i
(no default, initially white)
Works like lower left.
/tikz/upper right=hcolor i
(no default, initially white)
Works like lower left.
/tikz/lower right=hcolor i
(no default, initially white)
Works like lower left.
Shading color wheel
This shading fills the path with a color wheel.
\tikz \shade[shading=color wheel] (0,0) circle (1.5);
To produce a color ring, cut out a circle from the color wheel:
\tikz \shade[shading=color wheel] [even odd rule]
(0,0) circle (1.5)
(0,0) circle (1);
687
Shading color wheel black center
This shading looks like a color wheel, but the brightness drops to zero in the center.
\tikz \shade[shading=color wheel black center] (0,0) circle (1.5);
Shading color wheel white center
This shading looks like a color wheel, but the saturation drops to zero in the center.
\tikz \shade[shading=color wheel white center] (0,0) circle (1.5);
Shading Mandelbrot set
This shading is just for fun. It fills the path with a zoomable Mandelbrot set. Note that this is not
a bitmap graphic. Rather, the Mandelbrot set is computed by the pdf renderer and can be zoomed
arbitrarily (give it a try, if you have a fast computer).
\tikz \shade[shading=Mandelbrot set] (0,0) rectangle (2,2);
Shading radial
This always-defined shading fills the path with a gradual sweep from a certain color in the middle to
another color at the border. If the path is a circle, the outer color will be reached exactly at the border.
If the shading is not a circle, the outer color will continue a bit towards the corners. The default inner
color is gray, the default outer color is white.
/tikz/inner color=hcolor i
(no default)
This option sets the color used at the center of a radial shading. When this option is used, the
shade and shading=radial options are set.
\tikz \draw[inner color=red] (0,0) rectangle (2,1);
/tikz/outer color=hcolor i
(no default)
This option sets the color used at the border and outside of a radial shading.
\tikz \draw[outer color=red,inner color=white]
(0,0) rectangle (2,1);
688
66
Shadows Library
Tik Z Library shadows
\usepgflibrary{shadows}
\usepgflibrary[shadows]
\usetikzlibrary{shadows}
\usetikzlibrary[shadows]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library defines styles that help adding a (partly) transparent shadow to a path or node.
66.1
Overview
A shadow is usually a black or gray area that is drawn behind a path or a node, thereby adding visual depth
to a picture. The shadows library defines options that make it easy to add shadows to paths. Internally,
these options are based on using the preaction option to use a path twice: Once for drawing the shadow
(slightly shifted) and once for actually using the path.
Note that you can only add shadows to paths, not to whole scopes.
In addition to the general shadow option, there exist special options like circular shadow. These can
only (sensibly) be used with a special kind of path (for circular shadow, a circle) and, thus, they are not as
general. The advantage is, however, that they are more visually pleasing since these shadows blend smoothly
with the background. Note that these special shadows use fadings, which few printers will support.
66.2
The General Shadow Option
The shadows are internally created by using a single option called general shadow. The different options
like drop shadow or copy shadow only differ in the commands that they preset.
You will not need to use this option directly under normal circumstances.
/tikz/general shadow=hshadow optionsi
(default empty)
This option should be given to a \path or a node. It has the following effect: Before the path is used
normally, it is used once with the hshadow optionsi in force. Furthermore, when the path is “preused”
in this way, it is shifted and scaled a little bit.
In detail, the following happens: A preaction is used to paint the path in a special manner before it
is actually painted. This “special” manner is as follows: The options in hshadow optionsi are used for
painting this path. Typically, the hshadow optionsi will contain options like fill=black to create, say,
a black shadow. Furthermore, after the hshadow optionsi have been set up, the following extra canvas
transformations are applied to the path: It is scaled by shadow scale (with the origin of scaling at the
path’s center) and it is shifted by shadow xshift and shadow yshift.
Note that since scaling and shifting is done using canvas transformations, shadows are not taken into
account when the picture’s bounding box is computed.
\tikz [even odd rule]
\draw [general shadow={fill=red}] (0,0) circle (.5) (0.5,0) circle (.5);
/tikz/shadow scale=hfactor i
(no default, initially 1)
Shadows are scaled by hfactor i.
\tikz [even odd rule]
\draw [general shadow={fill=red,shadow scale=1.25}]
(0,0) circle (.5) (0.5,0) circle (.5);
(no default, initially 0pt)
/tikz/shadow xshift=hdimensioni
Shadows are shifted horizontally by hdimensioni.
\tikz [even odd rule]
\draw [general shadow={fill=red,shadow xshift=-5pt}]
(0,0) circle (.5) (0.5,0) circle (.5);
689
(no default, initially 0pt)
/tikz/shadow yshift=hdimensioni
Shadows are shifted vertically by hdimensioni.
66.3
66.3.1
Shadows for Arbitrary Paths and Shapes
Drop Shadows
/tikz/drop shadow=hshadow optionsi
(default empty)
This option adds a drop shadow to a \path or a node. It uses the general shadow and passes the
hshadow optionsi to it, plus, before them, the following extra options:
shadow scale=1, shadow xshift=.5ex, shadow yshift=-.5ex,
opacity=.5, fill=black!50, every shadow
\tikz [even odd rule]
\filldraw [drop shadow,fill=white] (0,0) circle (.5) (0.5,0) circle (.5);
Burst 4
\begin{tikzpicture}
\foreach \i in {1,...,4}
\node[starburst,drop shadow,fill=white,draw] at (0,\i) {Burst \i};
\end{tikzpicture}
Burst 3
Burst 2
Burst 1
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\filldraw [drop shadow={opacity=1},fill=white]
(1,2) circle (.5) (1.5,2) circle (.5);
\filldraw [drop shadow={opacity=0.25},fill=white]
(1,.5) circle (.5) (1.5,.5) circle (.5);
\end{tikzpicture}
(style, initially empty)
/tikz/every shadow
This style is executed in addition to any hshadow optionsi for each shadow. Use this style to reconfigure
the way shadows are drawn.
\begin{tikzpicture}[every shadow/.style={opacity=.8,fill=blue!50!black}]
\filldraw [drop shadow,fill=white] (0,0) circle (.5) (0.5,0) circle (.5);
\end{tikzpicture}
66.3.2
Copy Shadows
A copy shadow is not really a shadow. Rather, it looks like another copy of the path drawn behind the
path and a little bit offset. This creates the visual impression of having multiple copies of the path/object
present.
/tikz/copy shadow=hshadow optionsi
(default empty)
This shadow installs the following default options:
shadow scale=1, shadow xshift=.5ex, shadow yshift=-.5ex, every shadow
690
Furthermore, the options fill=hfill color i and draw=hdraw color i are also set, where the hfill color i and
hdraw color i are the fill and draw colors used for the main path.
Hello World!
Hello World!
Hello World!
Hello World!
\begin{tikzpicture}
\node [copy shadow,fill=blue!20,draw=blue,thick] {Hello World!};
\node at (0,-1) [copy shadow={shadow xshift=1ex,shadow yshift=1ex},
fill=blue!20,draw=blue,thick]
{Hello World!};
\node at (0,-2) [copy shadow={opacity=.5},tape,
fill=blue!20,draw=blue,thick]
{Hello World!};
% We have to repeat the left color since shadings are not
% automatically applied to shadows
\node at (0,-3) [copy shadow={left color=blue!50},
left color=blue!50,draw=blue,thick]
{Hello World!};
\end{tikzpicture}
/tikz/double copy shadow=hshadow optionsi
(default empty)
This shadow works like a copy shadow, only the shadow is added twice, the second time with the double
xshift and yshift.
Hello World!
Hello World!
Hello World!
Hello World!
\begin{tikzpicture}
\node [double copy shadow,fill=blue!20,draw=blue,thick] {Hello World!};
\node at (0,-1) [double copy shadow={shadow xshift=1ex,shadow yshift=1ex},
fill=blue!20,draw=blue,thick]
{Hello World!};
\node at (0,-2) [double copy shadow={opacity=.5},tape,
fill=blue!20,draw=blue,thick]
{Hello World!};
\node at (0,-3) [double copy shadow={left color=blue!50},
left color=blue!50,draw=blue,thick]
{Hello World!};
\end{tikzpicture}
66.4
Shadows for Special Paths and Nodes
The shadows in this section should normally be added only to paths that have a special shape. They will
look strange with other shapes.
/tikz/circular drop shadow=hshadow optionsi
(no default)
This shadow works like a drop shadow, only it adds a circular fading to the shadow. This means that
the shadow will fade out at the border. The following options are preset for this shadow:
shadow scale=1.1, shadow xshift=.3ex, shadow yshift=-.3ex,
fill=black, path fading={circle with fuzzy edge 15 percent},
every shadow,
Circle 2
Circle 3 Circle 1
Circle 4
\begin{tikzpicture}
\foreach \i in {1,...,8}
\node[circle,circular drop shadow,draw=blue,fill=blue!20,thick]
at (\i*45:1) {Circle \i};
\end{tikzpicture}
Circle 8
Circle 5 Circle 7
Circle 6
691
/tikz/circular glow=hshadow optionsi
(no default)
This shadow works much like the circular shadow, only it is not shifted. This creates a visual effect
of a “glow” behind the circle. The following options are preset for this shadow:
shadow scale=1.25, shadow xshift=0pt, shadow yshift=0pt,
fill=black, path fading={circle with fuzzy edge 15 percent},
every shadow,
Circle 2
Circle 3 Circle 1
Circle 4
\begin{tikzpicture}
\foreach \i in {1,...,8}
\node[circle,circular glow,fill=red!20,draw=red,thick]
at (\i*45:1) {Circle \i};
\end{tikzpicture}
Circle 8
Circle 5 Circle 7
Circle 6
Circle 2
Circle 3 Circle 1
Circle 4
\begin{tikzpicture}
\foreach \i in {1,...,8}
\node[circle,circular glow={fill=white},fill=red!20,draw=red,thick]
at (\i*45:1) {Circle \i};
\end{tikzpicture}
Circle 8
Circle 5 Circle 7
Circle 6
Circle 2
Circle 3 Circle 1
Circle 4
\begin{tikzpicture}
\foreach \i in {1,...,8}
\node[circle,circular glow={fill=green},fill=black,text=green!50!black]
at (\i*45:1) {Circle \i};
\end{tikzpicture}
Circle 8
Circle 5 Circle 7
Circle 6
An especially interesting effect can be achieved by only using the glow and not filling the path:
Circle 2
Circle 3 Circle 1
Circle 4
\begin{tikzpicture}
\foreach \i in {1,...,8}
\node[circle,circular glow={fill=red!\i0}]
at (\i*45:1) {Circle \i};
\end{tikzpicture}
Circle 8
Circle 5 Circle 7
Circle 6
692
67
Shape Library
67.1
Overview
In addition to the standard shapes rectangle, circle and coordinate, there exist a number of additional
shapes defined in different shape libraries. Most of these shapes have been contributed by Mark Wibrow. In
the present section, these shapes are described. Note that the library shapes is provided for compatibility
only. Please include sublibraries like shapes.geometric or shapes.misc directly.
The appearance of shapes is influenced by numerous parameters like minimum height or inner xsep.
These general parameters are documented in Section 17.2.3
In all of the examples presented in this section, the following shape example style is used:
\tikzset{
shape example/.style= {color
draw,
fill
line width
inner xsep
inner ysep
}
67.2
= black!30,
= yellow!30,
= .5cm,
= 2.5cm,
= 0.5cm}
Predefined Shapes
The three shapes rectangle, circle, and coordinate are always defined and no library needs to be loaded
for them. While the coordinate shape defines only the center anchor, the other two shapes define a
standard set of anchors.
Shape circle
This shape draws a tightly fitting circle around the text. The following figure shows the anchors this
shape defines; the anchors 10 and 130 are example of border anchors.
(s.north)
(s.130)
(s.north west)
(s.north east)
(s.10)
(s.center)
(s.west)
(s.east)
(s.mid)
(s.base west)
(s.mid west)
(s.text)
Circle
(s.mid east)
(s.base east)
(s.base)
(s.south west)
(s.south east)
(s.south)
693
\Huge
\begin{tikzpicture}
\node[name=s,shape=circle,shape example] {Circle\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{north west/above left, north/above, north east/above right,
west/left, center/above, east/right,
mid west/right, mid/above, mid east/left,
base west/left, base/below, base east/right,
south west/below left, south/below, south east/below right,
text/left, 10/right, 130/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape rectangle
This shape, which is the standard, is a rectangle around the text. The inner and outer separations (see
Section 17.2.3) influence the white space around the text. The following figure shows the anchors this
shape defines; the anchors 10 and 130 are example of border anchors.
(s.north west)
(s.130)
(s.north)
(s.north east)
(s.10)
(s.center)
(s.west)
(s.east)
(s.mid)
(s.base west)
(s.mid west)
(s.text)
Rectangle
(s.mid east)
(s.base east)
(s.base)
(s.south west)
(s.south)
(s.south east)
\Huge
\begin{tikzpicture}
\node[name=s,shape=rectangle,shape example] {Rectangle\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{north west/above left, north/above, north east/above right,
west/left, center/above, east/right,
mid west/right, mid/above, mid east/left,
base west/left, base/below, base east/right,
south west/below left, south/below, south east/below right,
text/left, 10/right, 130/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
67.3
Geometric Shapes
Tik Z Library shapes.geometric
\usepgflibrary{shapes.geometric}
\usepgflibrary[shapes.geometric]
\usetikzlibrary{shapes.geometric}
\usetikzlibrary[shapes.geometric]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library defines different shapes that correspond to basic geometric objects like ellipses or polygons.
Shape diamond
This shape is a diamond tightly fitting the text box. The ratio between width and height is 1 by default,
but can be changed by setting the shape aspect ratio using the following pgf key (to use this key in
Tik Z simply remove the /pgf/ path).
(no default, initially 1.0)
/pgf/aspect=hvaluei
The aspect is a recommendation for the quotient of the width and the height of a shape. This key
calls the macro \pgfsetshapeaspect.
694
The following figure shows the anchors this shape defines; the anchors 10 and 130 are example of border
anchors.
(s.north)
(s.130)
(s.north west)
(s.north east)
(s.10)
(s.center)
(s.west)
(s.east)
(s.mid)
(s.text)
Diamond
(s.base)
(s.south west)
(s.south east)
(s.south)
\Huge
\begin{tikzpicture}
\node[name=s,shape=diamond,shape example] {Diamond\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{north west/above left, north/above, north east/above right,
west/left, center/above, east/right,
mid/above,
base/below,
south west/below left, south/below, south east/below right,
text/left, 10/right, 130/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape ellipse
This shape is an ellipse tightly fitting the text box, if no inner separation is given. The following figure
shows the anchors this shape defines; the anchors 10 and 130 are example of border anchors.
695
(s.130)
(s.north)
(s.north west)
(s.north east)
(s.10)
(s.center)
(s.west)
(s.east)
(s.mid)
(s.base west)
(s.mid west)
(s.text)
Ellipse
(s.mid east)
(s.base east)
(s.base)
(s.south west)
(s.south east)
(s.south)
\Huge
\begin{tikzpicture}
\node[name=s,shape=ellipse,shape example] {Ellipse\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{north west/above left, north/above, north east/above right,
west/left, center/above, east/right,
mid west/right, mid/above, mid east/left,
base west/left, base/below, base east/right,
south west/below left, south/below, south east/below right,
text/left, 10/right, 130/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape trapezium
This shape is a trapezium, that is, a quadrilateral with a single pair of parallel lines (this can sometimes
be known as a trapezoid). The trapezium shape supports the rotation of the shape border, as described
in Section 17.2.3.
The lower internal angles at the lower corners of the trapezium can be specified independently, and the
resulting extensions are in addition to the natural dimensions of the node contents (which includes any
inner sep.
A
B
C
\begin{tikzpicture}
\tikzstyle{every node}=[trapezium, draw]
\node at (0,2) {A};
\node[trapezium left angle=75, trapezium right angle=45]
at (0,1) {B};
\node[trapezium left angle=120, trapezium right angle=60]
at (0,0) {C};
\end{tikzpicture}
The pgf keys to set the lower internal angles of the trapezium are shown below. To use these keys in
Tik Z, simply remove the /pgf/ path.
(no default, initially 60)
/pgf/trapezium left angle=hanglei
Sets the lower internal angle of the left side.
(no default, initially 60)
/pgf/trapezium right angle=hanglei
Sets the lower internal angle of the right side.
(style, no default)
/pgf/trapezium angle=hanglei
This key stores no value itself, but sets the value of the previous two keys to hanglei.
Regardless of the rotation of the shape border, the width and height of the trapezium are as follows:
696
\begin{tikzpicture}[>=stealth, every node/.style={text=black},
shape border uses incircle, shape border rotate=60]
\node [trapezium, fill=gray!25, minimum width=2cm] (t) {};
\draw [red, <->] (t.bottom left corner) -- (t.bottom right corner)
node [midway, below right] {width};
\draw [red, <->] (t.top side) -- (t.bottom side)
node [at start, above] {height};
\end{tikzpicture}
height
width
(default true)
/pgf/trapezium stretches=hbooleani
This key controls whether pgf allows the width and the height of the trapezium to be enlarged
independently, when considering any minimum size specification. This is initially false, ensuring
that the shape “looks the same but bigger” when enlarged.
\tikzset{my node/.style={trapezium, fill=#1!20, draw=#1!75, text=black}}
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\node [my node=red]
{A};
\node [my node=green, minimum height=1.5cm] at (1, 1.25) {B};
\node [my node=blue, minimum width=1.5cm] at (2, 0)
{C};
\end{tikzpicture}
B
A
C
By setting hbooleani to true, the trapezium can be stretched horizontally or vertically.
\tikzset{my node/.style={trapezium, fill=#1!20, draw=#1!75, text=black}}
\begin{tikzpicture}
\tikzset{trapezium stretches=true}
\draw [help lines] grid (3,2);
\node [my node=red]
{A};
\node [my node=green, minimum height=1.5cm] at (1, 1.25) {B};
\node [my node=blue, minimum width=1.5cm] at (2, 0)
{C};
\end{tikzpicture}
B
A
C
(default true)
/pgf/trapezium stretches body=hbooleani
This is similar to the trapezium stretches key except that when hbooleani is true, pgf enlarges
only the body of the trapezium when applying minimum width.
\tikzset{my node/.style={trapezium, fill=#1!20, draw=#1!75, text=black}}
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\node [my node=red]
at (1.5,.25) {A};
\node [my node=green, minimum width=3cm, trapezium stretches]
at (1.5,1)
{B};
\node [my node=blue, minimum width=3cm, trapezium stretches body]
at (1.5,1.75) {C};
\end{tikzpicture}
C
B
A
The anchors for the trapezium are shown below. The anchor 160 is an example of a border anchor.
(s.north west)
(s.top side)
(s.north east)
(s.top left corner)
(s.top right corner)
(s.north)
(s.160)
(s.west)
(s.left side)
(s.mid west)
(s.base west)
(s.east)
(s.right side)
(s.center)
Trapezium
(s.mid)
(s.text)
(s.mid east)
(s.base)
(s.base east)
(s.south)
(s.bottom left corner)
(s.south west)
(s.bottom side)
697
(s.south east)
(s.bottom right corner)
\Huge
\begin{tikzpicture}
\node[name=s, shape=trapezium, shape example, inner sep=1cm]
{Trapezium\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{bottom left corner/below, top right corner/right,
top left corner/left,
bottom right corner/below,
bottom side/below,
left side/left,
right side/right,
top side/above,
center/above,
text/below,
mid/right,
base/below,
mid west/right, base west/below, mid east/left,
base east/below,
west/above,
east/above,
north/below,
south/above,
north west/above, north east/above,
south west/below, south east/below, 160/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape semicircle
This shape is a semicircle, which tightly fits the node contents. This shape supports the rotation of the
shape border, as described in Section 17.2.3. The anchors for the semicircle shape are shown below.
Anchor 30 is an example of a border anchor.
(s.apex)
(s.north west)
(s.north east)
(s.north)
(s.30)
(s.center)
(s.west)
(s.mid west)
(s.text)
(s.east)
Semicircle
(s.mid)
(s.base)
(s.base west)
(s.mid east)
(s.base east)
(s.south)
(s.arc end)
(s.south west)
(s.chord center)
(s.south east)
(s.arc start)
\Huge
\begin{tikzpicture}
\node[name=s,shape=semicircle,shape border rotate=0,shape example, inner sep=1cm]
{Semicircle\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{apex/above,
arc start/below, arc end/below, chord center/below,
center/above,
base/below,
mid/right,
text/left,
base west/below, base east/below, mid west/left, mid east/right,
north/below,
south/above,
east/above,
west/above,
north west/above left, north east/above right,
south west/below,
south east/below, 30/right}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape regular polygon
This shape is a regular polygon, which, by default, is drawn so that a side (rather than a corner) is
always at the bottom. This shape supports the rotation as described in Section 17.2.3, but the border
of the polygon is always constructed using the incircle, whose radius is calculated to tightly fit the node
contents (including any inner sep).
698
\begin{tikzpicture}
\foreach \a in {3,...,7}{
\draw[red, dashed] (\a*2,0) circle(0.5cm);
\node[regular polygon, regular polygon sides=\a, draw,
inner sep=0.3535cm] at (\a*2,0) {};
}
\end{tikzpicture}
If the node is enlarged to any specified minimum size, this is interpreted as the diameter of the circumcircle, that is, the circle that passes through all the corners of the polygon border.
\begin{tikzpicture}
\foreach \a in {3,...,7}{
\draw[blue, dashed] (\a*2,0) circle(0.5cm);
\node[regular polygon, regular polygon sides=\a, minimum size=1cm, draw] at (\a*2,0) {};
}
\end{tikzpicture}
There is a pgf key to set the number of sides for the regular polygon. To use this key in Tik Z, simply
remove the /pgf/ path.
/pgf/regular polygon sides=hinteger i
(no default, initially 5)
The anchors for a regular polygon shape are shown below. The anchor 75 is an example of a border
anchor.
699
(s.corner 1)
(s.north)
(s.75)
(s.side 1)
(s.side 5)
(s.north east)
(s.north west)
(s.corner 2)
(s.corner 5)
(s.center)
(s.west)
(s.text)
(s.east)
Regular Polygon
(s.mid)
(s.base)
(s.side 2)
(s.side 4)
(s.south east)
(s.south west)
(s.south)
(s.corner 3)
(s.corner 4)
(s.side 3)
\Huge
\begin{tikzpicture}
\node[name=s, shape=regular polygon, shape example, inner sep=.5cm]
{Regular Polygon\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{corner 1/above, corner 2/above, corner 3/left, corner 4/right, corner 5/above,
side 1/above,
side 2/left,
side 3/below, side 4/right,
side 5/above,
center/above, text/left, mid/right,
base/below, 75/above,
west/above,
east/above, north/below, south/above,
north east/below, south east/above, north west/below, south west/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape star
This shape is a star, which by default (minus any transformations) is drawn with the first point pointing
upwards. This shape supports the rotation as described in Section 17.2.3, but the border of the star is
always constructed using the incircle.
A star should be thought of as having a set of “inner points” and “outer points”. The inner points of the
border are based on the radius of the circle which tightly fits the node contents, and the outer points
are based on the circumcircle, the circle that passes through every outer point. Any specified minimum
size, width or height, is interpreted as the diameter of the circumcircle.
S
\begin{tikzpicture}
\draw [help lines]
(0,0) grid (2,2);
\draw [blue, dashed] (1,1) circle(1cm);
\draw [red, dashed] (1,1) circle(.5cm);
\node [star, star point height=.5cm, minimum size=2cm, draw]
at (1,1) {S};
\end{tikzpicture}
700
The pgf keys to set the number of star points, and the height of the star points, are shown below. To
use these keys in Tik Z, simply remove the /pgf/ path.
/pgf/star points=hinteger i
(no default, initially 5)
Sets the number of points for the star.
(no default, initially .5cm)
/pgf/star point height=hdistancei
Sets the height of the star points. This is the distance between the inner point and outer point radii.
If the star is enlarged to some specified minimum size, the inner radius is increased to maintain the
point height.
/pgf/star point ratio=hnumber i
(no default, initially 1.5)
Sets the ratio between the inner point and outer point radii. If the star is enlarged to some specified
minimum size, the inner radius is increased to maintain the ratio.
The inner and outer points form the principle anchors for the star, as shown below (anchor 75 is an
example of a border anchor).
(s.outer point 1)
(s.north)
(s.75)
(s.inner point 1)
(s.inner point 5)
(s.north west)
(s.outer point 2)
(s.north east)
(s.west)
(s.center)
(s.inner point 2)
(s.text)
Star
(s.outer point 5)
(s.east)
(s.mid)
(s.inner point 4)
(s.base)
(s.south west)
(s.south)
(s.south east)
(s.inner point 3)
(s.outer point 3)
(s.outer point 4)
\Huge
\begin{tikzpicture}
\node[name=s, shape=star, star points=5, star point ratio=1.65, shape example, inner sep=1.5cm]
{Star\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{inner point 1/above, inner point 2/above, inner point 3/below, inner point 4/right,
inner point 5/above, outer point 1/above, outer point 2/above, outer point 3/left,
outer point 4/right, outer point 5/above,
center/above, text/left, mid/right,
base/below, 75/above,
west/above,
east/above, north/below, south/above,
north east/below, south east/above, north west/below, south west/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
701
Shape isosceles triangle
This shape is an isosceles triangle, which supports the rotation of the shape border, as described in
Section 17.2.3. The angle of rotation determines the direction in which the apex of the triangle points
(provided no other transformations are applied). However, regardless of the rotation of the shape border,
the width and height are always considered as follows:
width
height
\begin{tikzpicture}[>=stealth, every node/.style={text=black},
shape border uses incircle, shape border rotate=-30]
\node [isosceles triangle, fill=gray!25, minimum width=1.5cm] (t) {};
\draw [red, <->] (t.left corner) -- (t.right corner)
node [midway, above left] {width};
\draw [red, <->] (t.apex) -- (t.lower side)
node [midway, above right] {height};
\end{tikzpicture}
There are pgf keys to customize this shape. To use these keys in Tik Z, simply remove the /pgf/ path.
/pgf/isosceles triangle apex angle=hanglei
(no default, initially 30)
Sets the angle of the apex of the isosceles triangle.
/pgf/isosceles triangle stretches=hbooleani
(default true)
By default hbooleani is false. This means, that when applying any minimum width or minimum
height requirements, increasing the height will increase the width (and vice versa), in order to keep
the apex angle the same.
\begin{tikzpicture}[paint/.style={draw=#1!75, fill=#1!20}]
\tikzset{every node/.style={isosceles triangle, draw, inner sep=0pt,
anchor=left corner, shape border rotate=90}}
\draw[help lines] grid(4,2);
\foreach \a/\c in {1.5/blue, 1/green, 0.5/red}{
\node[paint=\c, minimum height=\a cm] at (0,0) {};
\node[paint=\c, minimum width=\a cm] at (2,0) {};
}
\end{tikzpicture}
However, by setting hbooleani to true, minimum width and height can be applied independently.
\begin{tikzpicture}[paint/.style={draw=#1!75, fill=#1!20}]
\tikzset{every node/.style={isosceles triangle, draw, inner sep=0pt,
anchor=south, shape border rotate=90, isosceles triangle stretches}}
\draw[help lines] grid(4,2);
\foreach \a/\c in {1.5/blue, 1/green, 0.5/red}{
\node[paint=\c, minimum height=\a cm, minimum width=1.5cm] at (0.75,0) {};
\node[paint=\c, minimum width=\a cm, minimum height=1.5cm] at (3,0)
{};
}
\end{tikzpicture}
The anchors for the isosceles triangle are shown below (anchor 150 is an example of a border
anchor). Note that, somewhat confusingly, the anchor names such as left side and right corner are
named as if the triangle is rotated to 90 degrees. Note also that the center anchor does not necessarily
correspond to any kind of geometric center.
702
(s.left corner)
(s.north west)
(s.north)
(s.150)
(s.left side)
(s.north east)
(s.west)
(s.apex)
(s.center)
(s.lower side)
(s.mid west)
Isosceles Triangle
(s.text)
(s.base west)
(s.mid)
(s.base)
(s.east)
(s.mid east)
(s.base east)
(s.south east)
(s.south)
(s.right side)
(s.south west)
(s.right corner)
\Huge
\begin{tikzpicture}
\node[name=s, shape=isosceles triangle, shape example, inner xsep=1cm]
{Isosceles Triangle\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{apex/above,
left corner/right, right corner/right,
left side/above, right side/below, lower side/right,
center/above,
text/right,
150/above,
mid/right,
mid west/above,
mid east/right,
base/below,
base west/below,
base east/below,
west/above, east/below, north/below, south/above,
north west/below, north east/below,
south west/above, south east/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape kite
This shape is a kite, which supports the rotation of the shape border, as described in Section 17.2.3.
There are pgf keys to specify the upper and lower vertex angles of the kite. To use these keys in Tik Z,
simply remove the /pgf/ path.
(no default, initially 120)
/pgf/kite upper vertex angle=hanglei
Sets the upper internal angle of the kite.
(no default, initially 60)
/pgf/kite lower vertex angle=hanglei
Sets the lower internal angle of the kite.
/pgf/kite vertex angles=hangle specificationi
(no default)
This key sets the keys for both the upper and lower vertex angles (it stores no value itself). hangle
specificationi can be pair of angles in the form hupper anglei and hlower anglei, or a single angle.
In this latter case, both the upper and lower vertex angles will be the same.
703
A
B
C
\begin{tikzpicture}
\tikzstyle{every node}=[kite, draw]
\node[kite upper vertex angle=135, kite lower vertex angle=70] at (0,0) {A};
\node[kite vertex angles=90 and 45] at (1,0) {B};
\node[kite vertex angles=60]
at (2,0) {C};
\end{tikzpicture}
The anchors for the kite are shown below. Anchor 110 is an example of a border anchor.
(s.upper vertex)
(s.110) (s.north)
(s.upper left side)
(s.upper right side)
(s.north west)
(s.north east)
(s.right vertex)
(s.left vertex)
(s.west)
(s.east)
(s.center)
(s.mid west)
(s.text)
(s.base west)
Kite
(s.mid)
(s.mid east)
(s.base)
(s.south west)
(s.base east)
(s.south east)
(s.lower left side)
(s.lower right side)
(s.south)
(s.lower vertex)
\Huge
\begin{tikzpicture}
\node[name=s, shape=kite, shape example, inner sep=1.5cm]
{Kite\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{upper vertex/above, left vertex/above,
lower vertex/below,
right vertex/above, upper left side/above, upper right side/above,
lower left side/below, lower right side/below,
center/above,
text/left,
mid/right,
base/below,
mid west/left, base west/below, mid east/right,
base east/below,
west/above,
east/above,
north/below,
south/above,
north west/left, north east/right,
south west/above, south east/above, 110/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape dart
This shape is a dart (which can also be known as an arrowhead or concave kite). This shape supports the
rotation of the shape border, as described in Section 17.2.3. The angle of the border rotation determines
the direction in which the dart points (unless other transformations have been applied).
There are pgf keys to set the angle for the ‘tip’ of the dart and the angle between the ‘tails’ of the dart.
To use these keys in Tik Z, simply remove the /pgf/ path.
704
tip angle
dart
tail angle
\begin{tikzpicture}
\node[dart, draw, gray, shape border uses incircle, shape border rotate=45]
(d) {dart};
\draw [<->] (d.tip)++(202.5:.5cm) arc(202.5:247.5:.5cm);
\node [left=.5cm] at (d.tip) {tip angle};
\draw [<->] (d.tail center)++(157.5:.5cm) arc(157.5:292.5:.5cm);
\node [right] at (d.tail center) {tail angle};
\end{tikzpicture}
(no default, initially 45)
/pgf/dart tip angle=hanglei
Sets the angle at the tip of the dart.
(no default, initially 135)
/pgf/dart tail angle=hanglei
Sets the angle between the tails of the dart.
The anchors for the dart shape are shown below (note that the shape is rotated 90 degrees anticlockwise). Anchor 110 is an example of a border anchor.
(s.tip)
(s.north)
(s.110)
(s.north west)
(s.north east)
(s.right side)
(s.left side)
(s.west)
(s.mid west)
(s.base west)
(s.east)
(s.center)
(s.text)
Dart
(s.mid)
(s.base)
(s.mid east)
(s.base east)
(s.south)
(s.tail center)
(s.south east)
(s.south west)
(s.left tail)
(s.right tail)
705
\Huge
\begin{tikzpicture}
\node[name=s, shape=dart, shape border rotate=90, shape example, inner sep=1.25cm]
{Dart\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{tip/above,
tail center/below, right tail/below,
left tail/below, right tail/below, left side/left,
right side/right,
center/above,
text/left,
mid/right,
base/below,
mid west/left,
base west/below,
mid east/right,
base east/below,
west/above,
east/above,
north/below,
south/above,
north west/left, north east/right, south west/above, south east/above,
110/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape circular sector
This shape is a circular sector (which can also be known as a wedge). This shape supports the rotation
of the shape border, as described in Section 17.2.3. The angle of the border rotation determines the
direction in which the ‘apex’ of the sector points (unless other transformations have been applied).
A
A
\begin{tikzpicture}
\tikzstyle{every node}=[circular sector, shape border uses incircle, draw];
\node at (0,0) {A};
\node [shape border rotate=30] at (1.5,0) {A};
\end{tikzpicture}
There is a pgf key to set the central angle of the sector, which is expected to be less than 180 degrees.
To use this key in Tik Z, simply remove the /pgf/ path.
(no default, initially 60)
/pgf/circular sector angle=hanglei
Sets the central angle of the sector.
The anchors for the circular sector shape are shown below. Anchor 30 is an example of a border anchor.
706
(s.arc start)
(s.north)
(s.north west)
(s.north east)
(s.30)
(s.west)
(s.center)
(s.sector center)
(s.arc center)
Circular Sector
(s.east)
(s.mid)
(s.text)
(s.base)
(s.south east)
(s.south west)
(s.south)
(s.arc end)
\Huge
\begin{tikzpicture}
\node[name=s,shape=circular sector, style=shape example, inner sep=1cm]
{Circular Sector\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{sector center/above, arc start/below, arc end/below, arc center/below,
center/above,
base/below,
mid/right,
text/below,
north/below,
south/above,
east/below,
west/above,
north west/above left, north east/above right,
south west/below,
south east/below, 30/right}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape cylinder
This shape is a 2-dimensional representation of a cylinder, which supports the rotation of the shape
border as described in Section 17.2.3.
ABC
\begin{tikzpicture}
\node[cylinder, draw, shape aspect=.5] {ABC};
\end{tikzpicture}
Regardless the rotation of the shape border, the height is always the distance between the curved ends,
and the width is always the distance between the straight sides.
width
d
lin
Cy
height
er
\begin{tikzpicture}[>=stealth]
\node [cylinder, gray!50, rotate=30, draw,
minimum height=2cm, minimum width=1cm] (c) {Cylinder};
\draw[red, <->] (c.top)
-- (c.bottom)
node [at end, below, black]
{height};
\draw[red, <->] (c.north) -- (c.south)
node [at start, above, black] {width};
\end{tikzpicture}
707
Enlarging the shape to some minimum height will stretch only the body of the cylinder. By contrast,
enlarging the shape to some minimum width will stretch the curved ends.
A
\begin{tikzpicture}[shape aspect=.5]
\tikzset{every node/.style={cylinder, shape border rotate=90, draw}}
\node [minimum height=1.5cm]
{A};
\node [minimum width=1.5cm] at (1.5,0) {B};
\end{tikzpicture}
B
There are various keys to customize this shape (to use pgf keys in Tik Z, simply remove the /pgf/
path).
(no default, initially 1.0)
/pgf/aspect=hvaluei
The aspect is a recommendation for the quotient of the radii of the cylinder end. This may be
ignored if the shape is enlarged to some minimum width.
A
B
C
\begin{tikzpicture}[]
\tikzset{every node/.style={cylinder, shape border rotate=90, draw}}
\node [aspect=1.0]
{A};
\node [aspect=0.5] at (1,0) {B};
\node [aspect=0.25] at (2,0) {C};
\end{tikzpicture}
(default true)
/pgf/cylinder uses custom fill=hbooleani
This enables the use of a custom fill for the body and the end of the cylinder. The background path
for the shape should not be filled (e.g., in Tik Z, the fill option for the node must be implicity
or explicitly set to none). Internally, this key sets the TEX-if \ifpgfcylinderusescustomfill
appropriately.
Cylinder
\begin{tikzpicture}[aspect=0.5]
\node [cylinder, cylinder uses custom fill, cylinder end fill=red!50,
cylinder body fill=red!25] {Cylinder};
\end{tikzpicture}
/pgf/cylinder end fill=hcolor i
(no default, initially white)
Sets the color for the end of the cylinder.
/pgf/cylinder body fill=hcolor i
(no default, initially white)
Sets the color for the body of the cylinder.
The anchors of this shape are shown below (anchor 160 is an example of a border anchor). Note that the
cylinder shape does not distinguish between outer xsep and outer ysep. Only the larger of the two
values is used for the shape. Note also the difference between the center and shape center anchors:
center is the center of the cylinder body and also the center of rotation. The shape center is the
center of the shape which includes the 2-dimensional representation of the cylinder top.
(s.north)
(s.after bottom)
(s.160)
(s.north east)
(s.before top)
(s.north west)
(s.bottom)
(s.west)
(s.top)
(s.center)
(s.shape center)
(s.mid west)
Cylinder
(s.text)
(s.base west)
(s.mid)
(s.base)
(s.east)
(s.mid east)
(s.base east)
(s.south west)
(s.before bottom)
(s.south)
(s.south east)
708
(s.after top)
\Huge
\begin{tikzpicture}
\node[name=s, shape=cylinder, shape example, aspect=.5, inner xsep=3cm,
inner ysep=1cm] {Cylinder\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{before top/above,
top/above,
after top/below,
before bottom/below, bottom/above,
after bottom/above,
mid/right,
mid west/right, mid east/left,
base/below,
base west/below, base east/below,
center/above,
text/above,
shape center/right,
west/right, east/left, north/above, south/below,
north west/below, north east/above,
south west/above, south east/below, 160/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
67.4
Symbol Shapes
Tik Z Library shapes.symbols
\usepgflibrary{shapes.symbols}
\usepgflibrary[shapes.symbols]
\usetikzlibrary{shapes.symbols}
\usetikzlibrary[shapes.symbols]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library defines shapes that can be used for drawing symbols like a forbidden sign or a cloud.
Shape correct forbidden sign
This shape places the node inside a circle with a diagonal from the upper left to the lower right added.
The circle is part of the background, the diagonal line part of the foreground path; thus, the diagonal
line is on top of the text.
Smoking
\begin{tikzpicture}
\node [correct forbidden sign,line width=1ex,draw=red,fill=white] {Smoking};
\end{tikzpicture}
The shape inherits all anchors from the circle shape.
Shape forbidden sign
This shape is like correct forbidden sign, only the line goes from the lower left to the upper right.
The strange naming of these shapes is for historical reasons.
Smoking
\begin{tikzpicture}
\node [forbidden sign,line width=1ex,draw=red,fill=white] {Smoking};
\end{tikzpicture}
The shape inherits all anchors from the circle shape.
Shape magnifying glass
This shape places the node inside a circle with a handle attached to the node. The angle of the handle
and its length can be adjusted using two keys:
/pgf/magnifying glass handle angle fill=hdegreei
(default -45)
The angle of the handle.
/pgf/magnifying glass handle angle aspect=hfactor i
The length of the handle as a multiple of the circle radius.
709
(default 1.5)
\begin{tikzpicture}
\node [magnifying glass,line width=1ex,draw] {huge};
\end{tikzpicture}
huge
The shape inherits all anchors from the circle shape.
Shape cloud
This shape is a cloud, drawn to tightly fit the node contents (strictly speaking, using an ellipse which
tightly fits the node contents – including any inner sep).
ABC
D
\begin{tikzpicture}
\node[cloud, draw, fill=gray!20, aspect=2] {ABC};
\node[cloud, draw, fill=gray!20] at (1.5,0) {D};
\end{tikzpicture}
A cloud should be thought of as having a number of “puffs”, which are the individual arcs drawn around
the border. There are pgf keys to specify how the cloud is drawn (to use these keys in Tik Z, simply
remove the /pgf/ path).
/pgf/cloud puffs=hinteger i
(no default, initially 10)
Sets the number of puffs for the cloud.
(no default, initially 135)
/pgf/cloud puff arc=hanglei
Sets the length of the puff arc (in degrees). A shorter arc can produce better looking joins between
puffs for larger line widths.
Like the diamond shape, the cloud shape also uses the aspect key to determine the ratio of the width
and the height of the cloud. However, there may be circumstances where it may be undesirable to
continually specify the aspect for the cloud. Therefore, the following key is implemented:
(default true)
/pgf/cloud ignores aspect=hbooleani
Instruct pgf to ignore the aspect key. Internally, the TEX-if \ifpgfcloudignoresaspect is set
appropriately. The initial value is false.
rain
snow
\begin{tikzpicture}[aspect=1, every node/.style={cloud, cloud puffs=11, draw}]
\node [fill=gray!20]
{rain};
\node [cloud ignores aspect, fill=white] at (1.5,0) {snow};
\end{tikzpicture}
Any minimum size requirements are applied to the “circum-ellipse”, which is the ellipse which passes
through all the midpoints of the puff arcs. These requirements are considered after any aspect specification is applied.
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\draw [blue, dashed] (1.5, 1) ellipse (1.5cm and 1cm);
\node [cloud, cloud puffs=9, draw, minimum width=3cm, minimum height=2cm]
at (1.5, 1) {};
\end{tikzpicture}
The anchors for the cloud shape are shown below for a cloud with eleven puffs. Anchor 70 is an example
of a border anchor.
710
(s.puff 1)
(s.puff 2)
(s.puff 11)
(s.70)
(s.north)
(s.north west)
(s.north east)
(s.puff 3)
(s.puff 10)
(s.center)
(s.east)
Cloud
(s.puff 9)
(s.west)
(s.puff 4)
(s.text)
(s.mid)
(s.base)
(s.puff 5)
(s.puff 8)
(s.south west)
(s.south east)
(s.south)
(s.puff 6)
(s.puff 7)
\Huge
\begin{tikzpicture}
\node[name=s, shape=cloud, style=shape example, cloud puffs=11, aspect=1.5,
cloud puff arc=120,inner ysep=1cm] {Cloud\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{puff 1/above, puff 2/above, puff 3/above, puff 4/below,
puff 5/left, puff 6/below, puff 7/below, puff 8/right,
puff 9/below, puff 10/above, puff 11/above, 70/right,
center/above, base/below,
mid/right,
text/left,
north/below, south/below,
east/above,
west/above,
north west/left,
north east/right,
south west/below,
south east/below}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape starburst
This shape is a randomly generated elliptical star, which supports the rotation of the shape border as
described in Section 17.2.3.
BANG!
\begin{tikzpicture}
\node[starburst, fill=yellow, draw=red, line width=2pt] {\bf BANG!};
\end{tikzpicture}
Like the star shape, the starburst should be thought of as having a set of inner points and outer points.
The inner points lie on the ellipse which tightly fits the node contents (including any inner sep).
Using a specified ‘starburst point height’ value, the outer points are generated randomly between this
value and one quarter of this value. For a given starburst shape, the angle between each point is fixed,
and is determined by the number of points specified for the starburst.
It is important to note that, whilst the maximum possible point height is used to calculate minimum
width or height requirements, the outer points are randomly generated, so there is (unfortunately) no
guarantee that any such requirements will be fully met.
711
\begin{tikzpicture}
\draw[help lines] grid(3,2);
\node[starburst, draw, minimum width=3cm, minimum height=2cm]
at (1.5, 1) {\bf BOOM!};
\end{tikzpicture}
BOOM!
There are pgf keys to control the drawing of the starburst shape. To use these keys in Tik Z, simply
remove the /pgf/ path.
/pgf/starburst points=hinteger i
(no default, initially 17)
Sets the number of outer points for the starburst.
(no default, initially .5cm)
/pgf/starburst point height=hlengthi
Sets the maximum distance between the inner point radius and the outer point radius.
/pgf/random starburst=hinteger i
(no default, initially 100)
Sets the seed for the random number generator for creating the starburst. The maximum value
for hinteger i is 16383. If hinteger i=0, the random number generator will not be used, and the
maximum point height will be used for all outer points. If hinteger i is omitted, a seed will be
randomly chosen.
The basic anchors for a nine point starburst shape are shown below. Anchor 80 is an example of a
border anchor.
(s.outer point 1)
(s.north)
(s.outer point 9)
(s.80)
(s.north east)
(s.outer point 2)
(s.north west)
(s.inner point 1)
(s.inner point 9)
(s.inner point 2)
(s.inner point 8)
(s.outer point 3)
(s.outer point 8)
(s.center)
(s.east)
(s.west)
(s.inner point 3)
(s.text)
Starburst
(s.mid)
(s.inner point 7)
(s.base)
(s.inner point 4)
(s.inner point 6)
(s.outer point 4)
(s.inner point 5)
(s.south west)
(s.south east)
(s.outer point 7)
(s.south)
(s.outer point 6)
(s.outer point 5)
712
\Huge
\begin{tikzpicture}
\node[name=s, shape=starburst, starburst points=9, starburst point height=3.5cm,
style=shape example,inner sep=1cm]
{Starburst\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{outer point 1/above, outer point 2/above, outer point 3/right,
outer point 4/above, outer point 5/below, outer point 6/above,
outer point 7/left, outer point 8/above, outer point 9/above,
inner point 1/below, inner point 2/above, inner point 3/left,
inner point 4/above, inner point 5/above, inner point 6/above,
inner point 7/below, inner point 8/above, inner point 9/below,
center/above, text/left,
mid/right, base/below, 80/above,
north/below, south/below, east/left, west/right,
north east/below, south west/below, south east/below, north west/below}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape signal
This shape is a “signal” or sign shape, that is, a rectangle, with optionally pointed sides. A signal can
point “to” somewhere, with outward points in that direction. It can also be “from” somewhere, with
inward points from that direction. The resulting points extend the node contents (which include the
inner sep).
To East
From East
\begin{tikzpicture}
[every node/.style={signal, draw, text=white, signal to=nowhere}]
\node[fill=green!65!black, signal to=east] at (0,1) {To East};
\node[fill=red!65!black, signal from=east] at (0,0) {From East};
\end{tikzpicture}
There are pgf keys for drawing the signal shape (to use these keys in Tik Z, simply remove the /pgf/
path):
(no default, initially 90)
/pgf/signal pointer angle=hanglei
Sets the angle for the pointed sides of the shape. This angle is maintained when enforcing any
minimum size requirements, so any adjustment to the width will affect the height, and vice versa.
/pgf/signal from=hdirectioni and hopposite directioni
(no default, initially nowhere)
Sets which sides take an inward pointer (i.e., that points towards the center of the shape). The
possible values for hdirectioni and hopposite directioni are the compass point directions north,
south, east and west (or above, below, right and left). An additional keyword nowhere can
be used to reset the sides so they have no pointers. When used with signal from key, this only
resets inward pointers; used with the signal to key, it only resets outward pointers.
/pgf/signal to=hdirectioni and hopposite directioni
(no default, initially east)
Sets which sides take an outward pointer (i.e., that points away from the shape).
Note that pgf will ignore any instruction to use directions that are not opposites (so using the value
east and north, will result in only north being assigned a pointer). This is also the case if non-opposite
values are used in the signal to and signal from keys at the same time. So, for example, it is not
possible for a signal to have an outward point to the left, and also have an inward point from below.
The anchors for the signal shape are shown below. Anchor 70 is an example of a border anchor.
713
(s.north west)
(s.north) (s.70)
(s.west)
(s.center)
(s.mid west)
(s.text)
(s.base west)
(s.south west)
(s.north east)
(s.east)
(s.mid east)
Signal
(s.mid)
(s.base)
(s.south)
(s.base east)
(s.south east)
\Huge
\begin{tikzpicture}
\node[name=s, shape=signal, signal from=west, shape example, inner sep=2cm]
{Signal\vrule width1pt height2cm};
\foreach \anchor/\placement in
{text/left,
center/above,
70/above,
base/below, base east/below, base west/below,
mid/right,
mid east/above left, mid west/above left,
north/above,
south/below,
east/above,
west/above,
north west/above, north east/above,
south west/below, south east/below}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape tape
This shape is a rectangle with optional, “bendy” top and bottom sides, which tightly fits the node
contents (including the inner sep).
ABCD
EFGH
\begin{tikzpicture}
\node[tape, draw]{ABCD};
\node[tape, draw, tape bend top=none] at (1.5, 0) {EFGH};
\end{tikzpicture}
There are pgf keys to specify which sides bend and how high the bends are (to use these keys in Tik Z,
simply remove the /pgf/ path):
/pgf/tape bend top=hbend stylei
(no default, initially in and out)
Specifies how the top side bends. The hbend stylei is either in and out, out and in or none (i.e.,
a straight line). The bending sides are drawn in a clockwise direction, and using the bend style in
and out will mean the side will first bend inwards and then bend outwards. The opposite holds
true for out and in.
in and out
Tape
\begin{tikzpicture}[-stealth]
\node[tape, draw, gray, minimum width=2cm](t){Tape};
\draw [blue]([yshift=5pt] t.north west) -- ([yshift=5pt]t.north east)
node[midway, above, black]{in and out};
\draw [blue]([yshift=-5pt]t.south east) -- ([yshift=-5pt]t.south west)
node[sloped, allow upside down, midway, above, black]{in and out};
\end{tikzpicture}
in and out
This might take a bit of getting used to, but just remember that when you want the bendy sides
to be parallel, the sides take the same bend style. It is possible for the top and bottom sides to
714
take opposite bend styles, but the author of this shape cannot think of a single use for such a
combination.
Why?
Parallel
\begin{tikzpicture}
\tikzstyle{every node}=[tape, draw]
\node [tape bend top=out and in, tape bend bottom=out and in] {Parallel};
\node at (2,0) [tape bend bottom=out and in]
{Why?};
\end{tikzpicture}
/pgf/tape bend bottom=hbend stylei
(no default, initially in and out)
Specifies how the bottom side bends.
(no default, initially 5pt)
/pgf/tape bend height=hlengthi
Sets the total height for a side with a bend.
tape bend height
\begin{tikzpicture}[>=stealth]
\draw [help lines] grid(3,2);
\node [tape, fill, minimum size=2cm, red!50, tape bend top=none,
tape bend height=1cm] at (1.5,1.5) (t) {};
\draw [|<->|, blue] (1.5,0) -- (1.5,1)
node [at end, above, black]{tape bend height};
\end{tikzpicture}
The anchors for the tape shape are shown below. Anchor 60 is an example of a border anchor. Note
that border anchors will snap to the center of convex curves (i.e. when bending in).
(s.60)
(s.north west)
(s.north)
(s.west)
(s.mid west)
(s.base west)
(s.south west)
(s.north east)
(s.center)
(s.text)
Tape
(s.mid)
(s.east)
(s.mid east)
(s.base)
(s.base east)
(s.south)
(s.south east)
\Huge
\begin{tikzpicture}
\node[name=s, shape=tape, tape bend height=1cm, shape example, inner xsep=3cm]
{Tape\vrule width1pt height2cm};
\foreach \anchor/\placement in
{text/left, center/above,
60/above,
base/below, base east/below, base west/below,
mid/right, mid east/left,
mid west/right,
north/above, south/below, east/above, west/above,
north west/above, north east/above,
south west/below, south east/below}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape magnetic tape
This shape represents a ‘magnetic tape’ or any sequential data store that is sometimes used in flowcharts.
It is essentially a circle with a little tail:
715
A
\tikz\node [magnetic tape, draw] (A) {A};
The following keys can be used to customise the magnetic tape shape:
/pgf/magnetic tape tail extend=hdistancei
(no default, initially 0cm)
This key sets how far the tail extends beyond the radius of the tape. Negative values will be ignored.
\begin{tikzpicture}[every node/.style={magnetic tape, draw}]
\node [magnetic tape tail extend=0cm]
at (0,0) {A};
\node [magnetic tape tail extend=0.25cm] at (0,1) {B};
\end{tikzpicture}
B
A
(no default, initially 0.15)
/pgf/magnetic tape tail=hproportioni
This key sets the thickness of the ‘tail’ to be hproportioni times the radius of the shape. The
hproportioni should be between 0.0 and 1.0.
\begin{tikzpicture}[every node/.style={magnetic tape, draw}]
\node [magnetic tape tail=0.5, magnetic tape tail extend=0.5cm] {A};
\node [magnetic tape tail=0.25] at (0,1) {B};
\end{tikzpicture}
B
A
The following figure shows the anchors this shape defines; the anchors 10 and 130 are example of border
anchors.
(s.north)
(s.130)
(s.north west)
(s.north east)
(s.10)
(s.center)
(s.west)
(s.mid west)
(s.text)
(s.base west)
(s.east)
Magnetic Tape
(s.mid)
(s.mid east)
(s.base east)
(s.base)
(s.tail north east)
(s.south west)
(s.tail east)
(s.south)
716
(s.south east)
(s.tail south east)
\Huge
\begin{tikzpicture}
\node[name=s,shape=magnetic tape,shape example,inner sep=0.75cm,
magnetic tape tail extend=0.5cm]
{Magnetic Tape\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{north west/above left, north/above, north east/above right,
west/left, center/above, east/right,
mid west/right, mid/right, mid east/left,
base west/below, base/below, base east/right,
south west/below left, south/below, south east/left,
text/left, 10/right, 130/above,
tail east/right, tail south east/below, tail north east/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
67.5
Arrow Shapes
Tik Z Library shapes.arrows
\usepgflibrary{shapes.arrows}
\usepgflibrary[shapes.arrows]
\usetikzlibrary{shapes.arrows}
\usetikzlibrary[shapes.arrows]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library defines arrow shapes. Note that an arrow shape is something quite different from a (normal)
arrow tip: It is a shape that just “happens” to “look like” an arrow. In particular, you cannot use these
shapes as arrow tips.
Shape single arrow
This shape is an arrow, which tightly fits the node contents (including any inner sep). This shape supports the rotation of the shape border, as described in Section 17.2.3. The angle of rotation determines
in which direction the arrow points (provided no other rotational transformations are applied).
37
◦
up
right
\begin{tikzpicture}[every node/.style={single arrow, draw},
rotate border/.style={shape border uses incircle, shape border rotate=#1}]
\node {right};
\node at (2,0) [shape border rotate=90]{up};
\node at (1,1) [rotate border=37, inner sep=0pt]{$37^\circ$};
\end{tikzpicture}
Regardless of the rotation of the arrow border, the width is measured between the back ends of the
arrow head, and the height is measured from the arrow tip to the end of the arrow tail.
height
width
\begin{tikzpicture}[>=stealth,
rotate border/.style={shape border uses incircle, shape border rotate=#1}]
\node[rotate border=-30, fill=gray!25, minimum height=3cm, single arrow,
single arrow head extend=.5cm, single arrow head indent=.25cm] (arrow) {};
\draw[red, <->] (arrow.before tip) -- (arrow.after tip)
node [near end, left, black] {width};
\draw[red, <->] (arrow.tip) -- (arrow.tail)
node [near end, below left, black] {height};
\end{tikzpicture}
There are pgf keys that can be used to customize this shape (to use these keys in Tik Z, simply remove
the /pgf/ path).
(no default, initially 90)
/pgf/single arrow tip angle=hanglei
Sets the angle for the arrow tip. Enlarging the arrow to some minimum width may increase the
height of the shape to maintain this angle.
(no default, initially .5cm)
/pgf/single arrow head extend=hlengthi
This sets the distance between the tail of the arrow and the outer end of the arrow head. This may
change if the shape is enlarged to some minimum width.
717
Ar
row
hea
d
ext
e
nd
\begin{tikzpicture}
\node[single arrow, draw, single arrow head extend=.5cm, gray!50, rotate=60]
(a) {Arrow};
\draw[red, |<->|] (a.before tip) -- (a.before head)
node [midway, below, sloped, black] {head extend};
\end{tikzpicture}
(no default, initially 0cm)
/pgf/single arrow head indent=hlengthi
2
arr
arr
ow
ow
1
This moves the point where the arrow head joins the shaft of the arrow towards the arrow tip, by
hlengthi.
\begin{tikzpicture}[every node/.style={single arrow, draw=none, rotate=60}]
\node [fill=red!50]
{arrow 1};
\node [fill=blue!50, single arrow head indent=1ex] at (1.5,0) {arrow 2};
\end{tikzpicture}
The anchors for this shape are shown below (anchor 20 is an example of a border anchor).
(s.before tip)
(s.north east)
(s.after tail)
(s.north west)
(s.west)
(s.north)
(s.before head)
(s.20)
(s.tip)
(s.center)
(s.tail)
(s.mid west)
(s.base west)
(s.before tail)
(s.mid)
(s.mid east)
Single Arrow
(s.text)
(s.base)
(s.south west)
(s.south)
(s.east)
(s.base east)
(s.after head)
(s.south east)
(s.after tip)
\Huge
\begin{tikzpicture}
\node[name=s,shape=single arrow, shape example, single arrow head extend=1.5cm]
{Single Arrow\vrule width1pt height2cm};
\foreach \anchor/\placement in
{text/above,
center/above, 20/above,
mid west/left,
mid/above,
mid east/above left,
base west/below, base/below,
base east/below,
tip/above, before tip/above, after tip/below, before head/above,
after head/below, after tail/above, before tail/below, tail/right,
north/above, south/below, east/below, west/above,
north west/above, north east/below, south west/below, south east/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape double arrow
This shape is a double arrow, which tightly fits the node contents (including any inner sep), and
supports the rotation of the shape border, as described in Section 17.2.3.
718
Left or Right
\begin{tikzpicture}[every node/.style={double arrow, draw}]
\node [double arrow, draw] {Left or Right};
\end{tikzpicture}
The double arrow behaves exactly like the single arrow, so you need to remember that the width is
always the distance between the back ends of the arrow heads, and the height is always the tip-to-tip
distance.
\begin{tikzpicture}[>=stealth,
rotate border/.style={shape border uses incircle, shape border rotate=#1}]
\node[rotate border=210, fill=gray!25, minimum height=3cm, double arrow,
double arrow head extend=.5cm, double arrow head indent=.25cm] (arrow) {};
\draw[red, <->] (arrow.before tip 1) -- (arrow.after tip 1)
node [near start, right, black] {width};
\draw[red, <->] (arrow.tip 1) -- (arrow.tip 2)
node [near end, above left, black] {height};
\end{tikzpicture}
height
width
The pgf keys that can be used to customize the double arrow behave similarly to the keys for the single
arrow (to use these keys in Tik Z, simply remove the /pgf/ path).
(no default, initially 90)
/pgf/double arrow tip angle=hanglei
Sets the angle for the arrow tip. Enlarging the arrow to some minimum width may increase the
height of the shape to maintain this angle.
(no default, initially .5cm)
/pgf/double arrow head extend=hlengthi
This sets the distance between the shaft of the arrow and the outer end of the arrow heads. This
may change if the shape is enlarged to some minimum width.
(no default, initially 0cm)
/pgf/double arrow head indent=hlengthi
This moves the point where the arrow heads join the shaft of the arrow towards the arrow tips, by
hlengthi.
ow
arr
ow
arr
2
1
\begin{tikzpicture}[every node/.style={double arrow, draw=none, rotate=-60}]
\node [fill=red!50]
{arrow 1};
\node [fill=blue!50, double arrow head indent=1ex] at (1.5,0) {arrow 2};
\end{tikzpicture}
The anchors for this shape are shown below (anchor 20 is an example of a border anchor).
719
(s.after tip 2)
(s.before tip 1)
(s.north west)
(s.north east)
(s.north)
(s.before head 1)
(s.20)
(s.after head 2)
(s.tip 2)
(s.west)
(s.tip 1)
(s.center)
(s.mid west)
(s.mid)
(s.mid east)
Double Arrow
(s.text)
(s.base west)
(s.base)
(s.east)
(s.base east)
(s.before head 2)
(s.south)
(s.south west)
(s.after head 1)
(s.south east)
(s.before tip 2)
(s.after tip 1)
\Huge
\begin{tikzpicture}
\node[name=s,shape=double arrow, double arrow head extend=1.5cm, shape example, inner xsep=2cm]
{Double Arrow\vrule width1pt height2cm};
\foreach \anchor/\placement in
{text/above, center/above, 20/above,
mid west/above right, mid/above, mid east/above left,
base west/below, base/below, base east/below,
before head 1/above, before tip 1/above, tip 1/above, after tip 1/below, after head 1/below,
before head 2/above, before tip 2/below, tip 2/above, after tip 2/above, after head 2/below,
north/above, south/below, east/below, west/below,
north west/below, north east/below, south west/above, south east/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape arrow box
This shape is a rectangle with optional arrows which extend from the four sides.
A
B
\begin{tikzpicture}
\node[arrow box, draw] {A};
\node[arrow box, draw, arrow box arrows={north:.5cm, west:0.75cm}]
at (2,0) {B};
\end{tikzpicture}
Any minimum size requirements are applied to the main rectangle only. This does not pose too many
problems if you wish to accommodate the length of the arrows, as it is possible to specify the length
of each arrow independently, from either the border of the rectangle (the default) or the center of the
rectangle.
One
Two
\begin{tikzpicture}
\tikzset{box/.style={arrow box, fill=#1}}
\draw [help lines] grid(3,2);
\node[box=blue!50, arrow box arrows={east:2cm}]
at (1,1.5){One};
\node[box=red!50, arrow box arrows={east:2cm from center}] at (1,0.5){Two};
\end{tikzpicture}
There are various pgf keys for drawing this shape (to use these keys in Tik Z, simply remove the /pgf/
path).
(no default, initially 90)
/pgf/arrow box tip angle=hanglei
720
Sets the angle at the arrow tip for all four arrows.
(no default, initially .125cm)
/pgf/arrow box head extend=hlengthi
Sets the distance the arrow head extends away from the shaft of the arrow. This applies to all
arrows.
(no default, initially 0cm)
/pgf/arrow box head indent=hlengthi
Moves the point where the arrow head joins the shaft of the arrow towards the arrow tip. This
applies to all arrows.
(no default, initially .125cm)
/pgf/arrow box shaft width=hlengthi
Sets the width of the shaft of all arrows.
(no default, initially .5cm)
/pgf/arrow box north arrow=hdistancei
Sets the distance the north arrow extends from the node. By default this is from the border of the
shape, but by using the additional keyword from center, the distance will be measured from the
center of the shape. If hdistancei is 0pt or a negative distance, the arrow will not be drawn.
(no default, initially .5cm)
/pgf/arrow box south arrow=hdistancei
Sets the distance the south arrow extends from the node.
(no default, initially .5cm)
/pgf/arrow box east arrow=hdistancei
Sets the distance the east arrow extends from the node.
(no default, initially .5cm)
/pgf/arrow box west arrow=hdistancei
Sets the distance the west arrow extends from the node.
(no default)
/pgf/arrow box arrows={hlisti}
Sets the distance that all arrows extend from the node. The specification in hlisti consists of the four
compass points north, south, east or west, separated by commas (so the list must be contained
within braces). The distances can be specified after each side separated by a colon (e.g., north:1cm,
or west:5cm from center). If an item specifies no distance, the most recently specified distance
will be used (at the start of the list this is 0cm, so the first item in the list should specify a distance).
Any sides not specified will not be drawn with an arrow.
The anchors for this shape are shown below (unfortunately, due to its size, this example must be rotated).
Anchor 75 is an example of a border anchor. If a side is drawn without an arrow, the anchors for that
arrow should be considered unavailable. They are (unavoidably) defined, but default to the center of
the appropriate side.
721
(s.before north arrow tip)
(s.south west)
(s.north arrow tip)
(s.north)
(s.75)
(s.after north arrow tip)
(s.after east arrow)
(s.after east arrow tip)
(s.after east arrow head)
(s.mid east)
(s.base east)
(s.east)
(s.east arrow tip)
(s.before east arrow head)
(s.before east arrow tip)
(s.after north arrow head)
(s.north east)
(s.before east arrow)
(s.after north arrow)
(s.center)
(s.mid)
(s.base)
(s.south east)
(s.before south arrow tip)
(s.before south arrow head)
(s.before south arrow)
(s.after south arrow)
(s.before west arrow)
Arrow Box
(s.text)
(s.after west arrow)
(s.north west)
(s.before north arrow)
(s.before north arrow head)
(s.after west arrow tip)
(s.after west arrow head)
(s.west arrow tip)
(s.west)
(s.mid west)
(s.base west)
(s.before west arrow head)
(s.before west arrow tip)
(s.after south arrow head)
(s.after south arrow tip)
(s.south arrow tip)
(s.south)
722
\Huge
\begin{tikzpicture}
\node[shape=arrow box, shape example, inner xsep=1cm, inner ysep=1.5cm, arrow box shaft width=2cm,
arrow box arrows={north:3.5cm from border, south, east:5cm from border, west},
arrow box head extend=0.75cm, rotate=-90](s) {Arrow Box\vrule width1pt height2cm};
\foreach \anchor/\placement in
{center/above, text/above, mid/right, base/below, 75/above,
mid east/right, mid west/left, base east/right, base west/left,
north/below, south/below, east/below, west/below,
north east/above, south east/above, south west/below, north west/below,
north arrow tip/above,south arrow tip/above, east arrow tip/above, west arrow tip/above,
before north arrow/above, before north arrow head/below left, before north arrow tip/above left,
after north arrow tip/above right, after north arrow head/below right, after north arrow/below,
before south arrow/below, before south arrow head/above right, before south arrow tip/below right,
after south arrow tip/below left, after south arrow head/above left, after south arrow/above,
before east arrow/above, before east arrow head/above right, before east arrow tip/above,
after east arrow tip/below, after east arrow head/below right, after east arrow/below,
before west arrow/below, before west arrow head/below left, before west arrow tip/below,
after west arrow tip/above, after west arrow head/above left, after west arrow/below}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement, rotate=-90] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
67.6
Shapes with Multiple Text Parts
Tik Z Library shapes.multipart
\usepgflibrary{shapes.multipart}
\usepgflibrary[shapes.multipart]
\usetikzlibrary{shapes.multipart}
\usetikzlibrary[shapes.multipart]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library defines general-purpose shapes that are composed of multiple (text) parts.
Shape circle split
This shape is a multi-part shape consisting of a circle with a line in the middle. The upper part is the
main part (the text part), the lower part is the lower part.
q1
00
\begin{tikzpicture}
\node [circle split,draw,double,fill=red!20]
{
$q_1$
\nodepart{lower}
$00$
};
\end{tikzpicture}
The shape inherits all anchors from the circle shape and defines the lower anchor in addition. See
also the following figure:
723
(s.north)
(s.130)
(s.north west)
(s.north east)
(s.mid)
(s.mid west)
(s.base west)
(s.text)
text
(s.mid east)
(s.base east)
(s.base)
(s.west)
(s.east)
(s.center)
(s.lower)
lower
(s.south west)
(s.south east)
(s.south)
\Huge
\begin{tikzpicture}
\node[name=s,shape=circle split,shape example] {text\nodepart{lower}lower};
\foreach \anchor/\placement in
{north west/above left, north/above, north east/above right,
west/left, center/below, east/right,
mid west/right, mid/above, mid east/left,
base west/left, base/below, base east/right,
south west/below left, south/below, south east/below right,
text/left, lower/left, 130/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape circle solidus
This shape (due to Manuel Lacruz) is similar to the split circle, but the two text parts are arranged
diagonally.
q1
00
\begin{tikzpicture}
\node [circle solidus,draw,double,fill=red!20]
{
$q_1$
\nodepart{lower}
$00$
};
\end{tikzpicture}
724
(s.north)
(s.130)
(s.north west)
(s.base west)
(s.mid west)
(s.text)
(s.north east)
text
(s.mid)
(s.mid east)
(s.base east)
(s.base)
(s.west)
(s.east)
(s.center)
(s.lower)
lower
(s.south west)
(s.south east)
(s.south)
\Huge
\begin{tikzpicture}
\node[name=s,shape=circle solidus,shape example,inner xsep=1cm] {text\nodepart{lower}lower};
\foreach \anchor/\placement in
{north west/above left, north/above, north east/above right,
west/left, center/below, east/right,
mid west/right, mid/above, mid east/left,
base west/left, base/below, base east/right,
south west/below left, south/below, south east/below right,
text/left, lower/left, 130/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape ellipse split
This shape is a multi-part shape consisting of an ellipse with a line in the middle. The upper part is
the main part (the text part), the lower part is the lower part. The anchors for this shape are shown
below. Anchor 60 is a border anchor.
725
(s.north)
(s.60)
(s.north west)
(s.north east)
(s.mid west)
(s.mid)
(s.base west)
(s.text)
(s.west)
(s.mid east)
text
(s.base)
(s.base east)
(s.center)
(s.lower)
(s.east)
lower
(s.south west)
(s.south east)
(s.south)
\Huge
\begin{tikzpicture}
\node[name=s,shape=ellipse split,shape example] {text\nodepart{lower}lower};
\foreach \anchor/\placement in
{center/below, text/left, lower/left, 60/above right,
mid/above, mid east/above, mid west/above,
base/right, base east/left, base west/right,
north/above, south/below, east/below, west/below,
north east/above, south east/below, south west/below, north west/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape rectangle split
This shape is a rectangle which can be split either horizontally or vertically into several parts.
a
b
c
d
e
1 2 3 4 5
1 2 3 4
A
B
C
\begin{tikzpicture}[my shape/.style={
rectangle split, rectangle split parts=#1, draw, anchor=center}]
\node [my shape=5] at (0,1)
{a\nodepart{two}b\nodepart{three}c\nodepart{four}d\nodepart{five}e};
\node [my shape=5, rectangle split horizontal] at (2,2)
{1\nodepart{two}2\nodepart{three}3\nodepart{four}4\nodepart{five}5};
\node [my shape=3] at (3,0.5)
{A\nodepart{two}B\nodepart{three}C};
\node [my shape=4, rectangle split horizontal] at (1.5,0.5)
{1\nodepart{two}2\nodepart{three}3\nodepart{four}4};
\end{tikzpicture}
The shape can be split into a maximum of twenty parts. However, to avoid allocating a lot of unnecessary boxes, pgf only allocates four boxes by default. To use the rectangle split shape with
more than four boxes, the extra boxes must be allocated manually in advance (perhaps using \newbox
or \let). The boxes take the form \pgfnodeparthnumber ibox, where hnumber i is from the cardinal
numbers one, two, three, . . . and so on. \pgfnodepartonebox is special in that it is synonymous
with \pgfnodeparttextbox. For compatibility with earlier versions of this shape, the boxes \pgfnodeparttwobox, \pgfnodepartthreebox and \pgfnodepartfourbox, can be referred to using the ordinal
numbers: \pgfnodepartsecondbox, \pgfnodepartthirdbox and \pgfnodepartfourthbox. In order
to facilitate the allocation of these extra boxes, the following key is provided:
/pgf/rectangle split allocate boxes=hnumber i
(no default)
This key checks if hnumber i boxes have been allocated, and if not, it allocates the required boxes
using \newbox (some “magic” is performed to get around the fact that \newbox is declared \outer
in plain TEX).
When split vertically, the rectangle split will meet any minimum width requirements, but any
minimum height will be ignored. Conversely when split horizontally, minimum height requirements
726
will be met, but any minimum width will be ignored. In addition, inner sep is applied to every part
that is used, so it cannot be specified independently for a particular part.
There are several pgf keys to specify how the shape is drawn. To use these keys in Tik Z, simply remove
the /pgf/ path:
/pgf/rectangle split parts=hnumber i
(no default, initially 4)
Split the rectangle into hnumber i parts, which should be in the range 1 to 20. If more than four
parts are needed, the boxes should be allocated in advance as described above.
Student
age:int
name:String
getAge():int
getName():String
\begin{tikzpicture}[every text node part/.style={align=center}]
\node[rectangle split, rectangle split parts=3, draw, text width=2.75cm]
{Student
\nodepart{two}
age:int \\
name:String
\nodepart{three}
getAge():int \\
getName():String};
\end{tikzpicture}
(default true)
/pgf/rectangle split horizontal=hbooleani
This key determines whether the rectangle is split horizontally or vertically
/pgf/rectangle split ignore empty parts=hbooleani
(default true)
When hbooleani is true, pgf will ignore any part that is empty except the text part. This effectively
overrides the rectangle split parts key in that, if 3 parts (for example) are specified, but one
is empty, only two will be shown.
text
text
third
third
\begin{tikzpicture}[every node/.style={draw, anchor=text, rectangle split,
rectangle split parts=3}]
\node {text \nodepart{second} \nodepart{third}third};
\node [rectangle split ignore empty parts] at (2,0)
{text \nodepart{second} \nodepart{third}third};
\end{tikzpicture}
/pgf/rectangle split empty part width=hlengthi
(no default, initially 1ex)
Sets the default width for a node part box if it is empty and empty parts are not ignored.
/pgf/rectangle split empty part height=hlengthi
(no default, initially 1ex)
Sets the default height for a node part box if it is empty and empty parts are not ignored.
/pgf/rectangle split empty part depth=hlengthi
(no default, initially 0ex)
Sets the default depth for a node part box if it is empty and empty parts are not ignored.
(no default, initially center)
/pgf/rectangle split part align={hlisti}
Sets the alignment of the boxes inside the node parts. Each item in hlisti should be separated by
commas (so if there is more than one item in hlisti, it must be surrounded by braces).
When the rectangle is split vertically, the entries in hlisti must be one of left, right, or center.
If hlisti has less entries than node parts then the remaining boxes are aligned according to the last
entry in the list. Note that this only aligns the boxes in each part and does not affect the alignment
of the contents of the boxes.
one
2
three
4
one
2
three
4
one
2
three
4
\def\x{one \nodepart{two} 2 \nodepart{three} three \nodepart{four} 4}
\begin{tikzpicture}[
every node/.style={rectangle split, rectangle split parts=4,
draw}
]
\node[rectangle split part align={center, left, right}] at (0,0)
{\x};
\node[rectangle split part align={center, left}]
at (1.25,0) {\x};
\node[rectangle split part align={center}]
at (2.5,0) {\x};
\end{tikzpicture}
727
When the rectangle is split horizontally, the entries in hlisti must be one of top, bottom, center
or base. Note that using the value base will only make sense if all the node part boxes are being
aligned in this way. This is because the base value aligns the boxes in relation to each other,
whereas the other values align the boxes in relation to the part of the shape they occupy.
y
w x y
w x y
w x y
w
x
z
z
z
\def\x{\Large w\nodepart{two}x\nodepart{three}\Huge y\nodepart{four}\tiny z}
\begin{tikzpicture}[
every node/.style={rectangle split, rectangle split parts=4,
draw, rectangle split horizontal}
]
\node[rectangle split part align={center, top, bottom}] at (0,0)
{\x};
\node[rectangle split part align={center, top}]
at (0,-1.25) {\x};
\node[rectangle split part align={center}]
at (0,-2.5) {\x};
\node[rectangle split part align=base]
at (0,-3.75) {\x};
\end{tikzpicture}
z
/pgf/rectangle split draw splits=hbooleani
(default true)
Sets whether the line or lines between node parts will be drawn. Internally, this sets the TEX-if
\ifpgfrectanglesplitdrawsplits appropriately.
/pgf/rectangle split use custom fill=hbooleani
(default true)
This enables the use of a custom fill for each of the node parts (including the area covered by
the inner sep). The background path for the shape should not be filled (e.g., in Tik Z, the fill
option for the node must be implicity or explicitly set to none). Internally, this key sets the TEX-if
\ifpgfrectanglesplitusecustomfill appropriately.
(no default, initially white)
/pgf/rectangle split part fill={hlisti}
Sets the custom fill color for each node part shape. The items in hlisti should be separated by
commas (so if there is more than one item in hlisti, it must be surrounded by braces). If hlisti has
less entries than node parts, then the remaining node parts use the color from the last entry in the
list. This key will automatically set /pgf/rectangle split use custom fill.
\begin{tikzpicture}
\tikzset{every node/.style={rectangle split, draw, minimum width=.5cm}}
\node[rectangle split part fill={red!50, green!50, blue!50, yellow!50}]
\node[rectangle split part fill={red!50, green!50, blue!50}] at (0.75,0)
\node[rectangle split part fill={red!50, green!50}]
at (1.5,0)
\node[rectangle split part fill={red!50}]
at (2.25,0)
\end{tikzpicture}
{};
{};
{};
{};
The anchors for the rectangle split shape split vertically into four, are shown below (anchor 70 is
an example of a border angle). When a node part is missing, the anchors prefixed with the name of
that node part should be considered unavailable. They are (unavoidably) defined, but default to other
anchor positions.
728
(s.north west)
(s.north)
(s.text west)
(s.mid)
(s.text)
(s.70)
(s.north east)
(s.text east)
text
(s.base)
(s.text split west)
(s.text split east)
(s.text split)
(s.two west)
(s.two)
(s.two split west)
(s.two east)
two
(s.two split east)
(s.center)
(s.two split)
(s.west)
(s.three west)
(s.east)
(s.three)
three
(s.three east)
(s.three split)
(s.three split west)
(s.four west)
(s.three split east)
(s.four)
(s.south west)
four
(s.four east)
(s.south)
(s.south east)
\Huge
\begin{tikzpicture}
\node[name=s,shape=rectangle split, rectangle split parts=4, shape example,
inner ysep=0.75cm]
{\nodepart{text}text\nodepart{two}two
\nodepart{three}three\nodepart{four}four};
\foreach \anchor/\placement in
{text/left, text east/above, text west/above,
two/left, two east/above, two west/above,
three/left, three east/below, three west/below,
four/left, four east/below, four west/below,
text split/left, text split east/above, text split west/above,
two split/left, two split east/above, two split west/above,
three split/left, three split east/below, three split west/below,
north/above, south/below, east/below, west/below,
north west/above, north east/above, south west/below, south east/below,
center/above, 70/above, mid/above, base/below}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
67.7
Callout Shapes
Tik Z Library shapes.callouts
\usepgflibrary{shapes.callouts}
\usepgflibrary[shapes.callouts]
\usetikzlibrary{shapes.callouts}
\usetikzlibrary[shapes.callouts]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
Producing basic callouts can be done quite easily in pgf and Tik Z by creating a node and then subsequently drawing a path from the border of the node to the required point. This library provides more
fancy, ‘balloon’-style callouts.
729
Callouts consist of a main shape and a pointer (which is part of the shape) which points to something in
(or outside) the picture. The position on the border of the main shape to which the pointer is connected is
determined automatically. However, the pointer is ignored when calculating the minimum size of the shape,
and also when positioning anchors.
Hallo!
\begin{tikzpicture}[remember picture]
\node[ellipse callout, draw] (hallo) {Hallo!};
\end{tikzpicture}
There are two kinds of pointer: the “relative” pointer and the “absolute” pointer. The relative pointer
calculates the angle of a specified coordinate relative to the center of the main shape, locates the point on
the border to which this angle corresponds, and then adds the coordinate to this point. This seemingly
over-complex approach means than you do not have to guess the size of the main shape: the relative pointer
will always be outside. The absolute pointer, on the other hand, is much simpler: it points to the specified
coordinate absolutely (and can even point to named coordinates in different pictures).
Outside
Relative
Absolute
\begin{tikzpicture}[remember picture, note/.style={rectangle callout, fill=#1}]
\draw [help lines] grid(3,2);
\node [note=red!50, callout relative pointer={(0,1)}] at (3,1) {Relative};
\node [note=blue!50, callout absolute pointer={(0,1)}] at (1,0) {Absolute};
\node [note=green!50, opacity=.5, overlay,
callout absolute pointer={(hallo.south)}]
at (1,2) {Outside};
\end{tikzpicture}
The following keys are common to all callouts. Please remember that the callout relative pointer,
and callout absolute pointer keys take a different format for their value depending on whether they are
being used in pgf or Tik Z.
(no default, initially \pgfpointpolar{315}{.5cm})
/pgf/callout relative pointer=hcoordinatei
Sets the vector of the callout pointer ‘relative’ to the callout shape.
(no default)
/pgf/callout absolute pointer=hcoordinatei
Sets the vector of the callout pointer absolutely within the picture.
(no default, initially (315:.5cm))
/tikz/callout relative pointer=hcoordinatei
The Tik Z version of the callout relative pointer key. Here, hcoordinatei can be specified using the
Tik Z format for coordinates.
(no default)
/tikz/callout absolute pointer=hcoordinatei
The Tik Z version of the callout absolute pointer key. Here, hcoordinatei can be specified using the
Tik Z format for coordinates.
It is also possible to shorten the pointer by some distance, using the following key:
(no default, initially 0cm)
/pgf/callout pointer shorten=hdistancei
Moves the callout pointer towards the center of the callout’s main shape by hdistancei.
\begin{tikzpicture}
\tikzset{callout/.style={ellipse callout, callout pointer arc=30,
callout absolute pointer={#1}}}
\draw (0,0) grid (3,2);
\node[callout={(3,1.5)}, fill=red!50] at (0,1.5) {A};
\node[callout={(3,.5)}, fill=green!50, callout pointer shorten=1cm]
at (0,.5) {B};
\end{tikzpicture}
A
B
Shape rectangle callout
This shape is a callout whose main shape is a rectangle, which tightly fits the node contents (including
any inner sep). It supports the keys described above and also the following key:
(no default, initially .25cm)
/pgf/callout pointer width=hlengthi
Sets the width of the pointer at the border of the rectangle.
730
The anchors for this shape are shown below (anchor 60 is an example of a border anchor). The pointer
direction is ignored when placing anchors. Additionally, when using an absolute pointer, the pointer
anchor should not to be used to used to position the shape as it is calculated whilst the shape is being
drawn.
(s.north west)
(s.north)
(s.north east)
(s.60)
(s.west)
(s.mid west)
(s.base west)
(s.center)
(s.east)
Rectangle Callout
(s.mid)
(s.text)
(s.south west)
(s.mid east)
(s.base)
(s.base east)
(s.south)
(s.south east)
(s.pointer)
\Huge
\begin{tikzpicture}
\node[name=s,shape=rectangle callout, callout relative pointer={(1.25cm,-1cm)},
callout pointer width=2cm, shape example, inner xsep=2cm, inner ysep=1cm]
{Rectangle Callout\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{center/above, text/below,
60/above,
mid/right,
mid west/left, mid east/right,
base/below,
base west/below, base east/below,
north/above, south/below, east/above, west/above,
north west/above, north east/above,
south west/below, south east/below,
pointer/below}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape ellipse callout
This shape is a callout whose main shape is an ellipse, which tightly fits the node contents (including any inner sep). It uses the absolute callout pointer, relative callout pointer and
callout pointer shorten keys, and also the following key:
(no default, initially 15)
/pgf/callout pointer arc=hanglei
Sets the width of the pointer at the border of the ellipse according to an arc of length hanglei.
The anchors for this shape are shown below (anchor 60 is an example of a border anchor). The pointer
direction is ignored when placing anchors and the pointer anchor can only be used to position the
shape when the relative anchor is specified.
731
(s.north)
(s.60)
(s.north west)
(s.north east)
(s.west)
(s.center)
(s.east)
(s.mid)
(s.mid west)
(s.base west)
Ellipse Callout
(s.text)
(s.base)
(s.mid east)
(s.base east)
(s.south west)
(s.south east)
(s.south)
(s.pointer)
\Huge
\begin{tikzpicture}
\node[name=s,shape=ellipse callout, callout relative pointer={(1.25cm,-1cm)},
callout pointer width=2cm, shape example, inner xsep=1cm, inner ysep=.5cm]
{Ellipse Callout\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{center/above, text/below,
60/above,
mid/above,
mid west/right, mid east/left,
base/below,
base west/below, base east/below,
north/above, south/below, east/above, west/above,
north west/above left,
north east/above right,
south west/below left,
south east/below right,
pointer/below}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape cloud callout
This shape is a callout whose main shape is a cloud which fits the node contents. The pointer is
segmented, consisting of a series of shrinking ellipses. This callout requires the symbol shape library
(for the cloud shape). If this library is not loaded an error will result.
Imagine...
\begin{tikzpicture}
\node[cloud callout, cloud puffs=15, aspect=2.5, cloud puff arc=120,
shading=ball,text=white] {\bf Imagine...};
\end{tikzpicture}
The cloud callout supports the absolute callout pointer, relative callout pointer and
callout pointer shorten keys, as described above. The main shape can be modified using the same
keys as the cloud shape. The following keys are also supported:
(no default, initially .2 of callout)
/pgf/callout pointer start size=hvaluei
Sets the size of the first segment in the pointer (i.e., the segment nearest the main cloud shape).
There are three possible forms for hvaluei:
• A single dimension (e.g., 5pt), in which case the first ellipse will have equal diameters of 5pt.
• Two dimensions (e.g., 10pt and 2.5pt), which sets the x and y diameters of the first ellipse.
• A decimal fraction (e.g., .2 of callout), in which case the x and y diameters of the first
ellipse will be set as fractions of the width and height of the main shape. The keyword of
callout cannot be omitted.
(no default, initially .1 of callout)
/pgf/callout pointer end size=hvaluei
732
Sets the size of the last ellipse in the pointer.
/pgf/callout pointer segments=hnumber i
(no default, initially 2)
Sets the number of segments in the pointer. Note that pgf will happily overlap segments if too
many are specified.
The anchors for this shape are shown below (anchor 70 is an example of a border anchor). The pointer
direction is ignored when placing anchors and the pointer anchor can only be used to position the shape
when the relative anchor is specified. Note that the center of the last segment is drawn at the pointer
anchor.
(s.puff 1)
(s.puff 2)
(s.puff 11)
(s.70)
(s.north)
(s.north east)
(s.north west)
(s.puff 3)
(s.puff 10)
(s.west)
(s.puff 4)
(s.center)
(s.text)
(s.east)
Cloud Callout
(s.mid)
(s.puff 9)
(s.base)
(s.puff 5)
(s.puff 8)
(s.south west)
(s.south east)
(s.south)
(s.puff 6)
(s.puff 7)
(s.pointer)
\Huge
\begin{tikzpicture}
\node[name=s, shape=cloud callout, style=shape example, cloud puffs=11, aspect=1.5,
cloud puff arc=120,inner xsep=.5cm, callout pointer start size=.25 of callout,
callout pointer end size=.15 of callout, callout relative pointer={(315:4cm)},
callout pointer segments=2] {Cloud Callout\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{puff 1/above, puff 2/above, puff 3/above, puff 4/below,
puff 5/left, puff 6/below, puff 7/below, puff 8/right,
puff 9/below, puff 10/above, puff 11/above, 70/right,
center/above, base/below, mid/right, text/left,
north/below, south/below, east/above, west/above,
north west/left, north east/right,
south west/below, south east/below,pointer/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
67.8
Miscellaneous Shapes
Tik Z Library shapes.misc
\usepgflibrary{shapes.misc}
\usepgflibrary[shapes.misc]
\usetikzlibrary{shapes.misc}
\usetikzlibrary[shapes.misc]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
733
This library defines general-purpose shapes that do not fit into the previous categories.
Shape cross out
This shape “crosses out” the node. Its foreground path are simply two diagonal lines between the corners
of the node’s bounding box. Here is an example:
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\node [cross out,draw=red] at (1.5,1) {cross out};
\end{tikzpicture}
cross out
A useful application is inside text as in the following example:
Cross me out!
Cross \tikz[baseline] \node [cross out,draw,anchor=text] {me}; out!
This shape inherits all anchors from the rectangle shape, see also the following figure:
(s.north west)
(s.130)
(s.north)
(s.north east)
(s.10)
(s.center)
(s.west)
(s.east)
(s.mid)
(s.base west)
(s.mid west)
(s.text)
cross out
(s.mid east)
(s.base east)
(s.base)
(s.south west)
(s.south)
(s.south east)
\Huge
\begin{tikzpicture}
\node[name=s,shape=cross out,shape example] {cross out\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{north west/above left, north/above, north east/above right,
west/left, center/above, east/right,
mid west/right, mid/above, mid east/left,
base west/left, base/below, base east/right,
south west/below left, south/below, south east/below right,
text/left, 10/right, 130/above}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
Shape strike out
This shape is identical to the cross out shape, only its foreground path consists of a single line from
the lower left to the upper right.
Strike me out!
Strike \tikz[baseline] \node [strike out,draw,anchor=text] {me}; out!
See the cross out shape for the anchors.
Shape rounded rectangle
This shape is a rectangle which can have optionally rounded sides.
Hallo
\begin{tikzpicture}
\node[rounded rectangle, draw, fill=red!20]{Hallo};
\end{tikzpicture}
There are keys to specify how the sides are rounded (to use these keys in Tik Z, simply remove the /pgf/
path).
734
(no default, initially 180)
/pgf/rounded rectangle arc length=hanglei
Sets the length of the arcs for the rounded ends. Recommended values for hanglei are between 90
and 180.
\begin{tikzpicture}
\matrix[row sep=5pt, every node/.style={draw, rounded rectangle}]{
\node[rounded rectangle arc length=180] {180}; \\
\node[rounded rectangle arc length=120] {120}; \\
\node[rounded rectangle arc length=90] {90}; \\};
\end{tikzpicture}
180
120
90
/pgf/rounded rectangle west arc=harc typei
(no default, initially convex)
Sets the style of the rounding for the left side. The permitted values for harc typei are concave,
convex, or none.
\begin{tikzpicture}
\matrix[row sep=5pt, every node/.style={draw, rounded rectangle}]{
\node[rounded rectangle west arc=concave] {Concave}; \\
\node[rounded rectangle west arc=convex] {Convex}; \\
\node[rounded rectangle left arc=none]
{None};
\\};
\end{tikzpicture}
Concave
Convex
None
/pgf/rounded rectangle left arc=harc typei
Alternative key for specifying the west arc.
(style, no default)
/pgf/rounded rectangle east arc=harc typei
(no default, initially convex)
Sets the style of the rounding for the east side.
/pgf/rounded rectangle right arc=harc typei
(style, no default)
Alternative key for specifying the east arc.
The anchors for this shape are shown below (anchor 10 is an example of a border angle). Note that if
only one side is rounded, the center anchor will not be the precise center of the shape.
(s.north west)
(s.north)
(s.north east)
(s.10)
(s.west)
(s.center)
(s.east)
(s.mid)
(s.mid west)
(s.base west)
Rounded Rectangle
(s.text)
(s.south west)
(s.base)
(s.mid east)
(s.base east)
(s.south)
(s.south east)
\Huge
\begin{tikzpicture}
\node[name=s,shape=rounded rectangle, shape example, inner xsep=1.5cm, inner ysep=1cm]
{Rounded Rectangle\vrule width 1pt height 2cm};
\foreach \anchor/\placement in
{center/above, text/below,
10/above,
mid/above,
mid west/right, mid east/left,
base/below,
base west/below, base east/below,
north/above, south/below, east/above, west/above,
north west/above left,
north east/above right,
south west/below left,
south east/below right}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
735
Shape chamfered rectangle
This shape is a rectangle with optionally chamfered corners.
STOP!
\begin{tikzpicture}
\node[chamfered rectangle, white, fill=red, double=red, draw, very thick]
{\bf STOP!};
\end{tikzpicture}
There are pgf keys to specify how this shape is drawn (to use these keys in Tik Z simply remove the
/pgf/ path).
(no default, initially 45)
/pgf/chamfered rectangle angle=hanglei
Sets the angle from the vertical for the chamfer.
abc
123
\begin{tikzpicture}
\tikzset{every node/.style={chamfered rectangle, draw}}
\node[chamfered rectangle angle=30] {abc};
\node[chamfered rectangle angle=60] at (1.5,0) {123};
\end{tikzpicture}
(no default, initially .666ex)
/pgf/chamfered rectangle xsep=hlengthi
Sets the distance that the chamfer extends horizontally beyond the node contents (which includes
the inner sep). If hlengthi is large, such that the top and bottom chamfered edges would cross,
then hlengthi is ignored and the chamfered edges are drawn so that they meet in the middle.
def
456
\begin{tikzpicture}
\tikzset{every node/.style={chamfered rectangle, draw}}
\node[chamfered rectangle xsep=2pt] {def};
\node[chamfered rectangle xsep=2cm] at (1.5,0) {456};
\end{tikzpicture}
(no default, initially .666ex)
/pgf/chamfered rectangle ysep=hlengthi
Sets the distance that the chamfer extends vertically beyond the node contents. If hlengthi is large,
such that the left and right chamfered edges would cross, then hlengthi is ignored and the chamfered
edges are drawn so that they meet in the middle.
(no default, initially .666ex)
/pgf/chamfered rectangle sep=hlengthi
Sets both the xsep and ysep simultaneously.
(no default, initially chamfer all)
/pgf/chamfered rectangle corners=hlisti
Specifies which corners are chamfered. The corners are identified by their “compass point” directions
(i.e. north east, north west, south west, and south east), and must be separated by commas
(so if there is more than one corner in the list, it must be surrounded by braces). Any corners
not mentioned in hlisti are automatically not chamfered. Two additional values chamfer all and
chamfer none, are also permitted.
ghi
789
\begin{tikzpicture}
\tikzset{every node/.style={chamfered rectangle, draw}}
\node[chamfered rectangle corners=north west] {ghi};
\node[chamfered rectangle corners={north east, south east}] at (1.5,0) {789};
\end{tikzpicture}
The anchors for this shape are shown below (anchor 60 is an example of a border angle.
736
(s.before north west)
(s.north) (s.70)
(s.after north east)
(s.north west)
(s.north east)
(s.after north west)
(s.before north east)
(s.west)
(s.center)
(s.east)
(s.mid west)
Chamfered Rectangle
(s.mid east)
(s.base west)
(s.text)
(s.mid)
(s.base east)
(s.base)
(s.before south west)
(s.after south east)
(s.south west)
(s.after south west)
(s.south east)
(s.south)
(s.before south east)
\Huge
\begin{tikzpicture}
\node[name=s,shape=chamfered rectangle, chamfered rectangle sep=1cm,
shape example, inner ysep=1cm, inner xsep=.75cm]
{Chamfered Rectangle\vrule width1pt height2cm};
\foreach \anchor/\placement in
{text/right, center/above,
70/above,
base/below, base east/left, base west/right,
mid/right, mid east/above,
mid west/above,
north/above, south/below, east/above, west/above,
before north east/above, north east/above, after north east/above,
before north west/above, north west/above, after north west/above,
before south west/below, south west/below, after south west/below,
before south east/below, south east/below, after south east/below}
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
\end{tikzpicture}
737
68
Spy Library: Magnifying Parts of Pictures
Tik Z Library spy
\usetikzlibrary{spy} % LATEX and plain TEX
\usetikzlibrary[spy] % ConTEXt
The package defines options for creating pictures in which some part of the picture is repeated in another
area in a magnified way (as if you were looking through a spyglass, hence the name).
68.1
Magnifying a Part of a Picture
The idea behind the spy library is to make is easy to create high-density pictures in which some important
parts are repeated somewhere, but magnified as if you were looking through a spyglass:
\begin{tikzpicture}
[spy using outlines={circle, magnification=4, size=2cm, connect spies}]
\draw [help lines] (0,0) grid (3,2);
\draw [decoration=Koch curve type 1]
decorate { decorate{ decorate{ decorate{ (0,0) -- (2,0) }}}};
\spy [red] on (1.6,0.3)
in node [left] at (3.5,-1.25);
\spy [blue, size=1cm] on (1,1)
in node [right] at (0,-1.25);
\end{tikzpicture}
\begin{tikzpicture}[spy using overlays={size=12mm}]
\draw [decoration=Koch snowflake]
decorate { decorate{ decorate{ decorate{ (0,0) -- (2,0) }}}};
\spy [green,magnification=3] on (0.6,0.1) in node at (-0.3,-1);
\spy [blue,magnification=5] on (1,0.5)
in node at (1,-1);
\spy [red,magnification=10] on (1.6,0.1) in node at (2.3,-1);
\end{tikzpicture}
Note that this magnification uses what is called a canvas transformation in this manual: Everything is
magnified, including line width and text.
In order for “spying” to work, the picture obviously has to be drawn several times: Once at its normal
size and then again for each “magnifying glass.” Several keys and commands work in concert to make this
possible:
• You need to make Tik Z aware of the fact that a picture (or just a scope) is to be magnified. This is
done by adding the special key spy scope to a {scope} or {tikzpicture} (which is also just a scope).
Some special keys like spy using outlines implicitly set the spy scope.
• Inside this scope you may then use the command \spy, which is only available inside such scopes (so
there is no danger of you inadvertently using this command outside such a scope). This command has
a special syntax and will (at some point) create two nodes: One node that shows the magnified picture
(called the spy-in node) and another node showing which part of the original picture is magnified (called
the spy-on node). The spy-in node is, indeed, a normal node, so it can have any shape or border that
you like and you can apply all of Tik Z’s advanced features to it. The only difference compared to a
normal node is that instead of some “text” it contains a magnified version of the picture, clipped to
the size of the node.
The \spy command does not create the nodes immediately. Rather, the creation of these nodes is
postponed till the end of the spy scope in which the \spy command is used. This is necessary since
in order to repeat the whole scope inside the node containing the magnified version, the whole picture
needs to be available when this node is created.
A basic question any library for “magnifying things” has to address is how you specify which part of the
picture is to be magnified (the spy-on node) and where this magnified part is to be shown (the spy-in node).
There are two possible ways:
738
1. You specify the size and position of the spy-on node. Then the size of the spy-in node is determined by
the size of the spy-on node and the magnification factor – you can still decide where the spy-in node
should be placed, but not its size.
2. Alternatively, you specify the size and position of the spy-in node. Then, similarly to the first case,
the size of the spy-on node is determined implicitly and you can only decide where the spy-on node
should be placed, but not its size.
The spy library uses the second method: You specify the size and position of the spy-in nodes, the sizes
of the spy-on nodes are then computed automatically.
68.2
Spy Scopes
(default empty)
/tikz/spy scope=hoptionsi
This option may be used with a {scope} or any environment that creates such a scope internally (like
{tikzpicture}). It has the following effects:
• It resets a number of graphic state parameters, including the color, line style, and others. This is
necessary for technical reasons.
• It tells Tik Z that the content of the scope should be saved internally in a special box.
• It defines the command \spy so that it can be used inside the scope.
• At the end of the scope, the nodes belonging to the \spy commands used inside the scope are
created.
• The hoptionsi are saved in an internal style. Each time \spy is used, these hoptionsi will be used.
• Three keys are defined that provide useful shortcuts:
(no default)
/tikz/size=hdimensioni
Inside a spy scope, this is a shortcut for minimum size.
(no default)
/tikz/height=hdimensioni
Inside a spy scope, this is a shortcut for minimum height.
(no default)
/tikz/width=hdimensioni
Inside a spy scope, this is a shortcut for minimum width.
It is permissible to nest spy scopes. In this case, all \spy commands inside the inner spy scope only
have an effect on material inside the scope, whereas \spy commands outside the inner spy scope but
inside the outer spy scope allow you to “spy on the spy.”
\begin{tikzpicture}
[spy using outlines={rectangle, red, magnification=5,
size=1.5cm, connect spies}]
\begin{scope}
[spy using outlines={circle, blue,
magnification=3, size=1.5cm, connect spies}]
\draw [help lines] (0,0) grid (3,2);
\draw [decoration=Koch curve type 1]
decorate{ decorate{ decorate{ (0,0) -- (2,0) }}};
\spy on (1.6,0.3) in node (zoom) [left] at (3.5,-1.25);
\end{scope}
\spy on (zoom.north west) in node [right] at (0,-1.25);
\end{tikzpicture}
68.3
The Spy Command
\spy[hoptionsi] on hcoordinatei in node hnode optionsi;
This command can only be used inside a spy scope. Let us start with the syntax:
• The \spy command is not a special case of \path. Rather, it has a small parser of its own.
739
• Following the optional hoptionsi, you must write on, followed by a coordinate. This coordinate
will be the center of the area that is to be magnified.
• Following the hcoordinatei, you must write in node followed by some hnode optionsi. The syntax
for these options is the same as for a normal node path command, such as [left] or (foo) [red]
at (bar). However, hnode optionsi are not followed by a curly brace. Rather, the hnode optionsi
must directly be followed by a semicolon.
The effect of this command is the following: The hoptionsi, hcoordinatei, and hnode optionsi are stored
internally till the end of the current spy scope. This means that, in particular, you can reference any
node inside the spy scope, even if it is not yet defined when the \spy command is given. At the end
of the current spy scope, two nodes are created, called the spy-in node and the spy-on node.
• The spy-in node is the node that contains a magnified part of the picture (the node in which we
see on what we spy). This node is, indeed, a normal Tik Z node, so you can use all standard options
to style this node. In particular, you can specify a shape or a border color or a drop shadow or
whatever. The only thing that is special about this node is that instead of containing some normal
text, its “text” is the magnified picture.
To be precise, the picture of the spy scope is scaled by a certain factor, specified by the lens or
magnification options discussed below, and is shifted in such a way that the hcoordinatei lies at
the center of the spy-on node.
• The spy-on node is a node that is centered on the hcoordinatei and whose size reflects exactly the
area shown inside the spy-in node (the node containing on what we spy).
Let us now go over what happens in detail when the two nodes are created:
1. A scope is started. Two sets of options are used with this scope: First, the options passed to
the enclosing spy scope and then the hoptionsi (which will, thus, overrule the options of the
spy scope).
2. Then, the spy-on node is created. However, we will first discuss the spy-in node.
3. The spy-in node is created after the spy-on node (and, hence, will cover the spy-on node in case
they overlap). When this node is created, the hnode optionsi are used in addition to the effect
caused by the hoptionsi and the options of the {spy scope}. Additionally, the following style is
used:
(style, no value)
/tikz/every spy in node
This style is used with every spy-in node.
The position of the node (the at option) is set to the hcoordinatei by default, so that it will cover
the to-be-magnified area. You can change this by providing the at option yourself:
\begin{tikzpicture}
[spy using outlines={circle, magnification=3, size=1cm}]
\draw [decoration=Koch curve type 1]
decorate{ decorate{ decorate{ (0,0) -- (2,0) }}};
\spy [red] on (1.6,0.3) in node;
\spy [blue] on (1,1)
in node at (1,-1);
\end{tikzpicture}
No “text” can be specified for the node. Rather, the “text” shown inside this node is the picture of
the current spy scope, but canvas-transformed according to the following key:
/tikz/lens=hoptionsi
(no default)
The hoptionsi should contain transformation commands like scale or rotate. These transformations are applied to the picture when it is shown inside the spy-on node.
Since the most common transformation is undoubtedly a simple scaling, there is a special style for
this:
/tikz/magnification=hnumber i
(no default)
This has the same effect as saying lens={scale=hnumber i}.
740
Now, usually the size of a node is determined in such a way that it “fits” around the text of the
node. For a spy-on node this is not a good approach since the “text” of this node would contain
“the whole picture.” Because of this, Tik Z acts as if the “text” of the node has zero size. You must
then use keys like minimum size to cause the node to have a certain size. Note that the key size
is an abbreviation for minimum size inside a spy scope.
You can name the spy-on node in the usual ways. Additionally, the node is (also) always named
tikzspyinnode. Following the spy scope, you can use this node like any other node:
\begin{tikzpicture}
\begin{scope}
[spy using outlines={circle, magnification=3, size=2cm, connect spies}]
\draw [decoration=Koch curve type 1]
decorate{ decorate{ decorate{ (0,0) -- (2,0) }}};
\spy [red] on (1.6,0.3) in node (a) [left] at (3.5,-1.25);
\spy [blue, size=1cm] on (1,1) in node (b) [right] at (0,-1.25);
\end{scope}
\draw [ultra thick, green!50!black] (b) -- (a.north west);
\end{tikzpicture}
4. Once both nodes have been created, the current value of the following key is used to connect them:
(no default, initially empty)
/tikz/spy connection path=hcodei
The hcodei is executed after the spy-on and spy-in nodes have just been created. Inside this
hcodei, the two nodes can be accessed as tikzspyinnode and tikzspyonnode. For example,
the key connect spies sets this command to
\draw[thin] (tikzspyonnode) -- (tikzspyinnode);
Returning to the creation of the spy-in node: This node is centered on hcoordinatei (more precisely,
its anchor is set to center and the at option is set to hcoordinatei). Its size and shape are initially
determined in the same way as the size and shape of the spy-on node (unless, of course, you explicitly
provide a different shape for, say, the spy-on node locally, which is not really a good idea). Then,
additionally, the inverted transformation done by the lens option is applied, resulting in a node whose
size and shape exactly corresponds to the area in the picture that is shown in the spy-on node.
\begin{tikzpicture}
[spy using outlines={lens={scale=3,rotate=20}, size=2cm, connect spies}]
\draw [decoration=Koch curve type 1]
decorate{ decorate{ decorate{ (0,0) -- (2,0) }}};
\spy [red] on (1.6,0.3) in node at (2.5,-1.25);
\end{tikzpicture}
Like for the spy-in node, a style can be used to format the spy-on node:
(style, no value)
/tikz/every spy on node
This style is used with every spy-on node.
The spy-on node is named tikzspyonnode (but, as always, this node is only available after the spy
scope). If you have multiple spy-on nodes and you would like to access all of them, you need to use the
name key inside the every spy on node style.
The inner sep and outer sep of both spy-in and spy-on nodes are set to 0pt.
68.4
Predefined Spy Styles
There are some predefined styles that make using the spy library easier. The following two styles can be
used instead of spy scope, they pass their hoptionsi directly to spy scope. They additionally set up the
graphic styles to be used for the spy-in nodes and the spy-on nodes in some special way.
741
(default empty)
/tikz/spy using outlines=hoptionsi
This key creates a spy scope in which the spy-in node is drawn, but not filled, using a thick line; and
the spy-on node is drawn, but not filled, using a very thin line.
\begin{tikzpicture}
[spy using outlines={circle, magnification=3, size=1cm, connect spies}]
\draw [decoration=Koch curve type 1]
decorate{ decorate{ decorate{ (0,0) -- (2,0) }}};
\spy [red] on (1.6,0.3) in node at (3,1);
\end{tikzpicture}
(default empty)
/tikz/spy using overlays=hoptionsi
This key creates a spy scope in which both the spy-in and spy-on nodes are filled, but with the fill
opacity set to 20%.
\begin{tikzpicture}
[spy using overlays={circle, magnification=3, size=1cm, connect spies}]
\draw [decoration=Koch curve type 1]
decorate{ decorate{ decorate{ (0,0) -- (2,0) }}};
\spy [green] on (1.6,0.3) in node at (3,1);
\end{tikzpicture}
The following style is useful for connecting the spy-in and the spy-on nodes:
(no value)
/tikz/connect spies
Causes the spy-in and the spy-on nodes to be connected by a thin line.
\begin{tikzpicture}
[spy using overlays={circle, magnification=3, size=1cm}]
\draw [decoration=Koch curve type 2]
decorate{ decorate{ decorate{ (0,0) -- (2,0) }}};
\spy [green] on (1.6,0.1) in node at (3,1);
\spy [red,connect spies] on (0.5,0.4) in node at (1,1.5);
\end{tikzpicture}
68.5
Examples
Usually, the spy-in node and the spy-on node should have the same shape. However, you might also wish to
use the circle shape for the spy-on node and the magnifying glass shape for the spy-in node:
\tikzset{spy using mag glass/.style={
spy scope={
every spy on node/.style={
circle,
fill, fill opacity=0.2, text opacity=1},
every spy in node/.style={
magnifying glass, circular drop shadow,
fill=white, draw, ultra thick, cap=round},
#1
}}}
\begin{tikzpicture}[spy using mag glass={magnification=3, size=1cm}]
\draw [decoration=Koch curve type 2]
decorate{ decorate{ decorate{ (0,0) -- (2,0) }}};
\spy [green!50!black] on (1.6,0.1) in node at (2.5,-0.5);
\end{tikzpicture}
With the magnifying glass, you can also put it “on top” of the picture itself:
742
\begin{tikzpicture}
[spy scope={magnification=4, size=1cm},
every spy in node/.style={
magnifying glass, circular drop shadow,
fill=white, draw, ultra thick, cap=round}]
\draw [decoration=Koch curve type 2]
decorate{ decorate{ decorate{ (0,0) -- (2,0) }}};
\spy on (1.6,0.1) in node;
\end{tikzpicture}
743
69
SVG-Path Library
Tik Z Library svg.path
\usepgflibrary{svg.path}
\usepgflibrary[svg.path]
\usetikzlibrary{svg.path}
\usetikzlibrary[svg.path]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library defines a command that allows you to specify a path using the svg-syntax.
\pgfpathsvg{hpathi}
This command extends the current path by a hpathi given in the svg-path-data syntax. This syntax is
described in detail in Section 8.3 of the svg-specification, Version 1.1.
In principle, the complete syntax is supported and the library just provides a parser and a mapping to
basic layer commands. For instance, M 0 10 is mapped to \pgfpathmoveto{\pgfpoint{0pt}{10pt}}.
There are, however, a few things to be aware of:
• The computation underlying the arc commands A and a are not numerically stable, which may
result in quite imprecise arcs. Bézier curves, both quadratic and cubic, are not affected, neither
are arcs spanning degrees that are multiples of 90◦ .
• The dimensionless units of svg are always interpreted as points (pt). This is a problem with paths
like M 20000 0, which will raise an error message since TEX cannot handle dimensions larger than
about 16000 points.
• All coordinate and canvas transformations apply to the path in the usual fashion.
• The \pgfpathsvg command can be freely intermixed with other path commands.
\begin{pgfpicture}
\pgfpathsvg{M 0 0 l 20 0 0 20 -20 0 q 10 0 10 10
t 10 10 10 10 h -50 z}
\pgfusepath{stroke}
\end{pgfpicture}
744
70
To Path Library
Tik Z Library topaths
\usetikzlibrary{topaths} % LATEX and plain TEX
\usetikzlibrary[topaths] % ConTEXt
This library provides predefined to paths for use with the to path operation. After loading this package,
you can say for instance to [loop] to add a loop to a node.
This library is loaded automatically by Tik Z, so you do not need to load it yourself.
70.1
Straight Lines
The following style installs a to path that is simply a straight line from the start coordinate to the target
coordinate.
(no value)
/tikz/line to
Causes a straight line to be added to the path upon a to or an edge operation.
\tikz {\draw (0,0) to[line to] (1,0);}
70.2
Move-Tos
The following style installs a to path that simply “jumps” to the target coordinate.
(no value)
/tikz/move to
Causes a move to be added to the path upon a to or an edge operation.
\tikz \draw (0,0) to[line to] (1,0)
to[move to] (2,0) to[line to] (3,0);
70.3
Curves
The curve to style causes the to path to be set to a curve. The exact way this curve looks can be influenced
via a number of options.
(no value)
/tikz/curve to
Specifies that the to path should be a curve. This curve will leave the start coordinate at a certain
angle, which can be specified using the out option. It reaches the target coordinate also at a certain
angle, which is specified using the in option. The control points of the curve are at a certain distance
that is computed in different ways, depending on which options are set.
All of the following options implicitly cause the curve to style to be installed.
(no default)
/tikz/out=hanglei
The angle at which the curve leaves the start coordinate. If the start coordinate is a node, the start
coordinate is the point on the border of the node at the given hanglei. The control point will, thus,
lie at a certain distance in the direction hanglei from the start coordinate.
\begin{tikzpicture}[out=45,in=135]
\draw (0,0) to (1,0)
(0,0) to (2,0)
(0,0) to (3,0);
\end{tikzpicture}
(no default)
/tikz/in=hanglei
The angle at which the curve reaches the target coordinate.
/tikz/relative=htrue or falsei
(default true)
This option tells Tik Z whether the in and out angles should be considered absolute or relative.
Absolute means that an out angle of 30◦ means that the curve leaves the start coordinate at an
745
angle of 30◦ relative to the paper (unless, of course, further transformations have been installed).
A relative angle is, by comparison, measured relative to a straight line from the start coordinate
to the target coordinate. Thus, a relative angle of 30◦ means that the curve will bend to the left
from the line going straight from the start to the target. For the target, the relative coordinate is
measured in the same manner, namely relative to the line going from the start to the target. Thus,
an angle of 150◦ means that the curve will reach target coming slightly from the left.
\begin{tikzpicture}[out=45,in=135,relative]
\draw (0,0) to (1,0)
to (2,1)
to (2,2);
\end{tikzpicture}
\begin{tikzpicture}[out=90,in=90,relative]
\node [circle,draw] (a) at (0,0) {a};
\node [circle,draw] (b) at (1,1) {b};
\node [circle,draw] (c) at (2,2) {c};
c
\path (a) edge (b)
edge (c);
\end{tikzpicture}
b
a
(default last value)
/tikz/bend left=hanglei
This option sets out=hanglei,in=180 − hanglei,relative. If no hanglei is given, the last given
bend left or bend right angle is used.
1
start
1
0
q0
1
q1
q2
0
\begin{tikzpicture}[shorten >=1pt,node distance=2cm,on grid]
\node[state,initial] (q_0)
{$q_0$};
\node[state]
(q_1) [right=of q_0] {$q_1$};
\node[state,accepting](q_2) [right=of q_1] {$q_2$};
\path[->] (q_0) edge
edge [loop above]
edge [bend left]
edge [bend right]
(q_1) edge
\end{tikzpicture}
node
node
node
node
node
[above]
[above]
[below]
[above]
90
135
45
180
0
225
315
270
746
{0}
{1}
{1}
{0}
{1}
(q_1)
()
(q_2)
(q_2)
(q_2);
\begin{tikzpicture}
\foreach \angle in {0,45,...,315}
\node[rectangle,draw=black!50] (\angle) at (\angle:2) {\angle};
\foreach \from/\to in {0/45,45/90,90/135,135/180,
180/225,225/270,270/315,315/0}
\path (\from) edge [->,bend right=22,looseness=0.8] (\to)
edge [<-,bend left=22,looseness=0.8] (\to);
\end{tikzpicture}
(default last value)
/tikz/bend right=hanglei
Works like the bend left option, only the bend is to the other side.
(no default)
/tikz/bend angle=hanglei
Sets the angle to be used by the bend left or bend right, but without actually selecting the
curve to or the relative option. This is useful for globally specifying a bend angle for a whole
picture.
/tikz/looseness=hnumber i
(no default, initially 1)
This number specifies how “loose” the curve will be. In detail, the following happens: Tik Z computes
the distance between the start and the target coordinate (if the start and/or target coordinate
are nodes, the distance is computed between the points on their border). This distance is then
multiplied by a fixed factor and also by the factor hnumber i. The resulting distance, let us call it
d, is then used as the distance of the control points from the start and target coordinates.
The fixed factor has been chosen in such a way that if hnumber i is 1, if the in and out angles differ
by 90◦, then a quarter circle results:
\tikz \draw (0,0) to [out=0,in=-90]
(1,1);
\tikz \draw (0,0) to [out=0,in=-90,looseness=0.5] (1,1);
/tikz/out looseness=hnumber i
(no default)
Specifies the looseness factor for the out distance only.
/tikz/in looseness=hnumber i
(no default)
Specifies the looseness factor for the in distance only.
(no default)
/tikz/min distance=hdistancei
If the computed distance for the start and target coordinates are below hdistancei, then hdistancei
is used instead.
(no default)
/tikz/max distance=hdistancei
If the computed distance for the start and target coordinates are above hdistancei, then hdistancei
is used instead.
/tikz/out min distance=hdistancei
The minimum distance set only for the start coordinate.
(no default)
/tikz/out max distance=hdistancei
(no default)
The maximum distance set only for the start coordinate.
/tikz/in min distance=hdistancei
The minimum distance set only for the target coordinate.
(no default)
/tikz/in max distance=hdistancei
(no default)
The maximum distance set only for the target coordinate.
(no default)
/tikz/distance=hdistancei
747
Set the minimum and maximum distance to the same value hdistancei. Note that this causes any
computed distance d to be ignored and hdistancei to be used instead.
\begin{tikzpicture}[out=45,in=135,distance=1cm]
\draw (0,0) to (1,0)
(0,0) to (2,0)
(0,0) to (3,0);
\end{tikzpicture}
(no default)
/tikz/out distance=hdistancei
Sets the minimum and maximum out distance.
(no default)
/tikz/in distance=hdistancei
Sets the minimum and maximum in distance.
(no default)
/tikz/out control=hcoordinatei
This option causes the hcoordinatei to be used as the start control point. All computations of d are
ignored. You can use a coordinate like +(1,0) to specify a point relative to the start coordinate.
(no default)
/tikz/in control=hcoordinatei
This option causes the hcoordinatei to be used as the target control point.
(no default)
/tikz/controls=hcoordinateiandhcoordinatei
This option causes the hcoordinateis to be used as control points.
\tikz \draw (0,0) to [controls=+(90:1) and +(90:1)] (3,0);
70.4
Loops
(no value)
/tikz/loop
This key is similar to the curve to key, but differs in the following ways: First, the actual target
coordinate is ignored and the start coordinate is used as the target coordinate. Thus, it is allowed not
to provide any target coordinate, which can be useful with unnamed nodes. Second, the looseness
is set to 8 and the min distance to 5mm. These settings result in rather nice loops when the opening
angle (difference between in and out) is 30◦ .
\begin{tikzpicture}
\node [circle,draw] {a} edge [in=30,out=60,loop] ();
\end{tikzpicture}
a
(style, no value)
/tikz/loop above
Sets the loop style and sets in and out angles such that loop is above the node. Furthermore, the above
option is set, which causes a node label to be placed at the correct position.
x
a
\begin{tikzpicture}
\node [circle,draw] {a} edge [loop above] node {x} ();
\end{tikzpicture}
/tikz/loop below
Works like the previous option.
(style, no value)
/tikz/loop left
(style, no value)
Works like the previous option.
(style, no value)
/tikz/loop right
Works like the previous option.
748
(style, initially ->,shorten >=1pt)
/tikz/every loop
This style is installed at the beginning of every loop.
\begin{tikzpicture}[every loop/.style={}]
\draw (0,0) to [loop above] () to [loop right] ()
to [loop below] () to [loop left] ();
\end{tikzpicture}
749
71
Through Library
Tik Z Library through
\usetikzlibrary{through} % LATEX and plain TEX
\usetikzlibrary[through] % ConTEXt
This library defines keys for creating shapes that go through given points.
(no default)
/tikz/circle through=hcoordinatei
When this key is given as an option to a node, the following happens:
1. The inner sep and the outer sep are set to zero.
2. The shape is set to circle.
3. The minimum size is set such that the circle around the center of the node (which is specified
using at), goes through hcoordinatei.
a
c
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\node (a) at (2,1.5) {$a$};
\node [draw] at (1,1) [circle through={(a)}] {$c$};
\end{tikzpicture}
750
72
Tree Library
Tik Z Library trees
\usetikzlibrary{trees} % LATEX and plain TEX
\usetikzlibrary[trees] % ConTEXt
This packages defines styles to be used when drawing trees.
72.1
Growth Functions
The package trees defines two new growth functions. They are installed using the following options:
/tikz/grow via three points=one child at (hx i) and two children at (hyi) and (hz i)
default)
(no
This option installs a growth function that works as follows: If a parent node has just one child, this
child is placed at hx i. If the parent node has two children, these are placed at hyi and hz i. If the parent
node has more than two children, the children are placed at points that are linearly extrapolated from
the three points hx i, hyi, and hz i. In detail, the position is x + n−1
2 (y − x) + (c − 1)(z − y), where n is
the number of children and c is the number of the current child (starting with 1).
The net effect of all this is that if you have a certain “linear arrangement” in mind and use this option to
specify the placement of a single child and of two children, then any number of children will be placed
correctly.
Here are some arrangements based on this growth function. We start with a simple “above” arrangement:
one
\begin{tikzpicture}[grow via three points={%
one child at (0,1) and two children at (-.5,1) and (.5,1)}]
\node at (0,0) {one} child;
\node at (0,-1.5) {two} child child;
\node at (0,-3) {three} child child child;
\node at (0,-4.5) {four} child child child child;
\end{tikzpicture}
two
three
four
The next arrangement places children above, but “grows only to the right.”
one
\begin{tikzpicture}[grow via three points={%
one child at (0,1) and two children at (0,1) and (1,1)}]
\node at (0,0) {one} child;
\node at (0,-1.5) {two} child child;
\node at (0,-3) {three} child child child;
\node at (0,-4.5) {four} child child child child;
\end{tikzpicture}
two
three
four
In the final arrangement, the children are placed along a line going down and right.
751
\begin{tikzpicture}[grow via three points={%
one child at (-1,-.5) and two children at (-1,-.5) and (0,-.75)}]
\node at (0,0) {one} child;
\node at (0,-1.5) {two} child child;
\node at (0,-3) {three} child child child;
\node at (0,-4.5) {four} child child child child;
\end{tikzpicture}
one
two
three
four
These examples should make it clear how you can create new styles to arrange your children along a
line.
(no value)
/tikz/grow cyclic
This style causes the children to be arranged “on a circle.” For this, the children are placed at distance
\tikzleveldistance from the parent node, but not on a straight line, but on points on a circle. Instead
of a sibling distance, there is a sibling angle that denotes the angle between two given children.
(no default)
/tikz/sibling angle=hanglei
Sets the angle between siblings in the grow cyclic style.
Note that this function will rotate the coordinate system of the children to ensure that the grandchildren
will grow in the right direction.
\begin{tikzpicture}
[grow cyclic,
level 1/.style={level distance=8mm,sibling angle=60},
level 2/.style={level distance=4mm,sibling angle=45},
level 3/.style={level distance=2mm,sibling angle=30}]
\coordinate [rotate=-90] % going down
child foreach \x in {1,2,3}
{child foreach \x in {1,2,3}
{child foreach \x in {1,2,3}}};
\end{tikzpicture}
(no default)
/tikz/clockwise from=hanglei
This option also causes children to be arranged on a circle. However, the rule for placing children
is simpler than with the grow cyclic style: The first child is placed at hanglei at a distance of
\tikzleveldistance. The second child is placed at the same distance from the parent, but at angle hanglei − \tikzsiblingangle. The third child is displaced by another \tikzsiblingangle in a
clockwise fashion, and so on.
Note that this function will not rotate the coordinate system.
30
root
0
−30
−60
\begin{tikzpicture}
\node {root}
[clockwise from=30,sibling angle=30]
child {node {$30$}}
child {node {$0$}}
child {node {$-30$}}
child {node {$-60$}};
\end{tikzpicture}
(no default)
/tikz/counterclockwise from=hanglei
Works the same way as clockwise from, but sibling angles are added instead of subtracted.
752
72.2
Edges From Parent
The following styles can be used to modify how the edges from parents are drawn:
(style, no value)
/tikz/edge from parent fork down
This style will draw a line from the parent downwards (for half the level distance) and then on to the
child using only horizontal and vertical lines.
root
left
right
child child
\begin{tikzpicture}
\node {root}
[edge from parent fork down]
child {node {left}}
child {node {right}
child[child anchor=north east] {node {child}}
child {node {child}}
};
\end{tikzpicture}
(style, no value)
/tikz/edge from parent fork right
This style behaves similarly, only it will first draw its edge to the right.
child
right
root
child
left
\begin{tikzpicture}
\node {root}
[edge from parent fork right,grow=right]
child {node {left}}
child {node {right}
child {node {child}}
child {node {child}}
};
\end{tikzpicture}
(style, no value)
/tikz/edge from parent fork left
Behaves similarly to the previous styles.
(style, no value)
/tikz/edge from parent fork up
Behaves similarly to the previous styles.
753
73
Turtle Graphics Library
Tik Z Library turtle
\usepgflibrary{turtle}
\usepgflibrary[turtle]
\usetikzlibrary{turtle}
\usetikzlibrary[turtle]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This little library defines some keys to create simple turtle graphics in the tradition of the Logo programming language. These commands are mostly for fun, but they can also be used for more “serious”
business.
\tikz[turtle/distance=2mm]
\draw [turtle={home,forward,right,forward,left,forward,left,forward}];
Even though the turtle keys looks like an option, it uses the insert path option internally to produce
a path.
The basic drawing model behind the turtle graphics is very simple: There is a (virtual) turtle that crawls
around the page, thereby extending the path. The turtle always heads in a certain direction. When you
move the turtle forward, you extend the path in that direction; turning the turtle just changes the direction,
it does not cause anything to be drawn.
The turtle always moves relative to the last current point of the path and you can mix normal path
commands with turtle commands. However, the direction of the turtle is managed independently of other
path commands.
(no default)
/tikz/turtle=hkeysi
This key executes the hkeysi with the current key path set to /tikz/turtle.
\tikz[turtle/distance=2mm]
\draw [turtle={home,fd,rt,fd,lt,fd,lt,fd}];
(no value)
/tikz/turtle/home
Places the turtle at the origin and lets it head upward.
(default see text)
/tikz/turtle/forward=hdistancei
Makes the turtle move forward by the given hdistancei. If no hdistancei is specified, the current value
of the following key is used:
(no default, initially 1cm)
/tikz/turtle/distance=hdistancei
The default distance by which the turtle advances.
“Moving forward the turtle” actually means that, relative to the current last point on the path, a point
at the given hdistancei in the direction the turtle is currently heading is computed. Then, the operation
to[turtle/how] is used to extend the path to this point.
(style, initially empty)
/tikz/turtle/how
This style can set up the to path used by turtles. By setting this style you can change the
to-path:
\tikz \draw [turtle={how/.style={bend left},home,forward,right,forward}];
(no value)
/tikz/turtle/fd
An abbreviation for the forward key.
(default see text)
/tikz/turtle/back=hdistancei
This has the same effect as a turtle/forward for the negated hdistancei value.
754
(no value)
/tikz/turtle/bk
An abbreviation for the back key.
(default 90)
/tikz/turtle/left=hanglei
Turns the turtle left by the given angle.
(no value)
/tikz/turtle/lt
An abbreviation for the left key.
(default 90)
/tikz/turtle/right=hanglei
Turns the turtle right by the given angle.
(no value)
/tikz/turtle/rt
An abbreviation for the right key.
Turtle graphics are especially nice in conjunction with the \foreach statement:
\tikz \filldraw [thick,blue,fill=blue!20]
[turtle=home]
\foreach \i in {1,...,5}
{
[turtle={forward,right=144}]
};
755
Part VI
Data Visualization
by Till Tantau
1
0.8
0.6
0.4
e−x
2
0.2
P10
i=1
0
−5
−2.5
0
2.5
xi , where xi ∼ U (−1, 1)
5
\tikz \datavisualization [scientific axes=clean]
[
visualize as smooth line=Gaussian,
Gaussian={pin in data={text={$e^{-x^2}$},when=x is 1}}
]
data [format=function] {
var x : interval [-7:7] samples 51;
func y = exp(-\value x*\value x);
}
[
visualize as scatter,
legend={south east outside},
scatter={
style={mark=*,mark size=1.4pt},
label in legend={text={
$\sum_{i=1}^{10} x_i$, where $x_i \sim U(-1,1) $}}}
]
data [format=function] {
var i : interval [0:1] samples 20;
func y = 0;
func x = (rand + rand + rand + rand + rand +
rand + rand + rand + rand + rand);
};
756
74
Introduction to Data Visualization
Data visualization is the process of converting data points, which typically consist of multiple numerical
values, into a graphical representation. Examples include the well-known function plots, but pie charts, bar
diagrams, box plots, or vector fields are also examples of data visualizations.
The data visualization subsystem of pgf takes a general, open approach to data visualization. Like
everything else in pgf, there is a powerful, but not-so-easy-to-use basic layer in the data visualization
system and a less flexible, but much simpler-to-use frontend layer. The present section gives an overview of
the basic ideas behind the data visualization system.
74.1
Concept: Data Points
The most important input for a data visualization is always raw data. This data is typically present in
different formats and the data visualization subsystem provides methods for reading such formats and also
for defining new input formats. However, independently of the input format, we may ask what kind of data
the data visualization subsystem should be able to process. For two-dimensional plots we need lists of pairs
of real numbers. For a bar plot we usually need a list of numbers, possibly together with some colors and
labels. For a surface plot we need a matrix of triples of real numbers. For a vector field we need even more
complex data.
The data visualization subsystem makes no assumption concerning which kind of data is being processed.
Instead, the whole “rendering pipeline” is centered around a concept called the data point. Conceptually, a
data point is an arbitrarily complex record that represents one piece of data that should be visualized. Data
points are not just coordinates in the plane or the numerical values that need to be visualized. Rather, they
represent the basic units of the data that needs to be visualized.
Consider the following example: In an experiment we drive a car along a road and have different measurement instruments installed. We measure the position of the car, the time, the speed, the direction the
car is heading, the acceleration, and perhaps some further values. A data point would consist of a record
consisting of a timestamp together with the current position of the car (presumably two or three numbers),
the speed vector (another two or three numbers), the acceleration (another two or three numbers), and
perhaps the label text of the current experiment.
Data points should be “information rich.” They might even contain more information than what will
actually be visualized. It is the job of the rendering pipeline to pick out the information relevant to one
particular data visualization – another visualization of the same data might pick different aspects of the data
points, thereby hopefully allowing new insights into the data.
Technically, there is no special data structure for data points. Rather, when a special macro called
\pgfdatapoint is called, the “totality” of all currently set keys with the /data point/ prefix in the current
scope forms the data point. This is both a very general approach and quite fast since no extra data structures
need to be created.
74.2
Concept: Visualization Pipeline
The visualization pipeline is a series of actions that are performed on the to-be-visualized data. The data is
presented to the visualization pipeline in the form of a long stream of complex data points. The visualization
pipeline makes several passes over this stream of data points. During the first pass(es), called the survey
phase(s), information is gathered about the data points such as minimal and maximal values, which can
be useful for automatic fitting of the data into a given area. In the main pass over the data, called the
visualization phase, the data points are actually visualized, for instance in the form of lines or points.
Like as for data points, the visualized pipeline makes no assumptions concerning what kind of visualization
is desired. Indeed, one could even use it to produce a plain-text table. This flexibility is achieved by extensive
use of objects and signals: When a data visualization starts, a number of signals (see Section 93.9 for an
introduction to signals) are initialized. Then, numerous “visualization objects” are created that listen to
these signals. These objects are all involved in processing the data points. For instance, the job of an
interval mapper object is to map one attribute of a data point, such as a car’s velocity, to another, such as
the y-axis of a plot. For each data point the different signals are raised in a certain order and the different
visualization objects now have a chance of preparing the data point for the actual visualization. Continuing
the above example, there might be a second interval mapper that takes the computed y-position and
applies a logarithm to it, because a log-plot was requested. Then another mapper, this time a polar mapper
might be used to map everything to polar coordinates. Following this, a plot mark visualizer might
actually draw something at the computed position.
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The whole idea behind the rendering pipeline is that new kinds of data visualizations can be implemented,
ideally, just by adding one or two new objects to the visualization pipeline. Furthermore, different kinds of
plots can be combined in novel ways in this manner, which is usually very hard to do. For instance, the
visualization pipeline makes it easy to create, say, polar-semilog-box-plots. At first sight, such new kinds
of plots may seem frivolous, but data visualization is all about gaining insights into the data from as many
different angles as possible.
Naturally, creating new classes and objects for the rendering pipeline is not trivial, so most users will just
use the existing classes, which should, thus, be as flexible as possible. But even when one only intends to use
existing classes, it is still tricky to setup the pipeline correctly since the ordering is obviously important and
since things like axes and ticks need to be configured and taken care of. For this reason, the frontend libraries
provide preconfigured rendering pipelines so that one can simply say that a data visualization should look
like a line plot with school book axes or with scientific axes, which selects a certain visualization
pipeline that is appropriate for this kind of plot:
\begin{tikzpicture}[scale=.7]
\datavisualization [school book axes, visualize as smooth line]
data [format=function] {
var x : interval [-2:2];
func y = \value x*\value x + 1;
};
\end{tikzpicture}
5
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2
1
−2
−1 0
1
2
5
\begin{tikzpicture}[scale=.7]
\datavisualization [scientific axes, visualize as smooth line]
data [format=function] {
var x : interval [-2:2];
func y = \value x*\value x + 1;
};
\end{tikzpicture}
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3
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2
One must still configure such a plot (choose styles and themes and also specify which attributes of a data
point should be used), but on the whole the plot is quite simple to specify.
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75
75.1
Creating Data Visualizations
Overview
The present section explains how a data visualization is created in Tik Z. For this, you need to include the
datavisualization library and then use the command \datavisualization whose syntax is explained in
the rest of the present section. This command is part of the following library:
Tik Z Library datavisualization
\usetikzlibrary{datavisualization} % LATEX and plain TEX
\usetikzlibrary[datavisualization] % ConTEXt
This library must be loaded if you wish to use the \datavisualization command. It defines all styles
needed to create basic data visualizations; additional, more specialized libraries need to be loaded for
more advanced features.
In order to visualize, you basically need to do three things:
1. You need to select what kind of plot you would like to have (a “school book plot” or a “scientific 2d plot”
or a “scientific spherical plot” etc.). This is done by passing an option to the \datavisualization
command that selects this kind of plot.
2. You need to provide data points, which is done using the data command.
3. Additionally, you can add options that give you more fine-grained control over the way the visualization
will look. You can configure the number of ticks and grid lines, where the labels are placed, the colors,
or the fonts. Indeed, since the data visualization engine internally uses Tik Z-styles, you can have
extremely fine-grained control over how a plot will look like.
The syntax of the \datavisualization command is designed in such a way that if you only need to
provide very few options to create plots that “look good by default”.
This section is structured as follows: First, the philosophy behind concepts like “data points,” “axes,” or
“visualizers” is explained. Each of these concepts is further detailed in later section. Then, the syntax of the
\datavisualization command is covered. The reference sections explain which predefined plot kinds are
available.
75.2
Concept: Data Points and Data Formats
As explained in Section 74.1, data points are the basic entities that are processed by the data visualization
engine. In order to specify data points, you use the data command, whose syntax is explained in more detail
in Section 75.6. The data command allows you to either specify points “inline,” directly inside your TEX-file;
or you can specify the name of file that contains the data points.
Specifying data points. Data points can be formatted in different ways. For instance, in the so
called comma separated values format, there is one line for each data point and the different attributes of a
data point are separated by commas. Another common format is to specify data points using the so called
key-value format, where on each line the different attributes of a data point are set using a comma-separated
list of strings of the form attribute=value.
Here are two examples, where similar data is given in different formats:
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0
1
\begin{tikzpicture}
\datavisualization [school book axes, visualize as smooth line]
data {
x, y
-1.5, 2.25
-1, 1
-.5, .25
0, 0
.5, .25
1, 1
1.5, 2.25
};
\end{tikzpicture}
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\begin{tikzpicture}
\datavisualization [school book axes, visualize as smooth line]
data [format=function] {
var x : interval [-1.5:1.5] samples 7;
func y = \value x*\value x;
};
\end{tikzpicture}
2
1
−1
0
1
In the first example, no format needed to be specified explicitly since the default format is the one used
for the data following the data keyword: A list of comma-separated values, where each line represents a
data point.
Number accuracy. Data visualizations typically demand a much higher accuracy and range of values
than TEX provides: TEX numbers are limited to 13 bits for the integer part and 16 bits for the fractional
part. Because of this, the data visualization engine does not use pgf’s standard representation of numbers
and TEX dimensions and is does not use the standard parser when reading numbers in a data point. Instead,
the fpu library, described in Section 54, is used to handle numbers.
This use of the fpu library has several effects that users of the data visualization system should be aware
of:
1. You can use numbers like 100000000000000 or 0.00000000001 in a data points.
2. Since the fpu library does not support advanced parsing, you currently cannot write things like 3+2
in a data point number. This will result in an error
3. However, there is a loop-hole: If a “number” in a data point starts with a parenthesis, the value between
the parentheses is parsed using the normal parser:
• 100000 is allowed.
• 2+3 yields an error.
• (2+3) is allowed and evaluates to 5.
• (100000) yields an error since 100000 is beyond the normal parser’s precision.
The bottom line is that any normal calculations should be set inside round parentheses, while large
numbers should not be surrounded by parentheses. Hopefully, in the future, these restrictions will be
lifted.
Section 76 gives an in-depth coverage of the available data formats and explains how new data formats
can be defined.
75.3
Concept: Axes, Ticks, and Grids
Most plots have two or three axes: A horizontal axis usually called the x-axis, a vertical axis called the
y-axis, and possibly some axis pointing in a sloped direction called the z-axis. Axes are usually drawn as
lines with ticks indicating interesting positions on the axes. The data visualization engine gives you detailed
control over where these ticks are rendered and how many of them are used. Great care is taken to ensure
that the position of ticks are chosen well by default.
From the point of view of the data visualization engine, axes are a somewhat more general concept than
“just” lines that point “along” some dimension: The data visualization engine uses axes to visualize any
change of an attribute by varying the position of data points in the plane. For instance, in a polar plot,
there is an “axis” for the angle and another “axis” for the distance if the point from the center. Clearly these
axes vary the position of data points in the plane according to some attribute of the data points; but just
as clearly they do not point in any “direction.”
A great benefit of this approach is that the powerful methods for specifying and automatic inference
of “good” positions for ticks or grid lines apply to all sorts of situations. For instance, you can use it to
automatically put ticks and grid lines at well-chosen angles of a polar plot.
Typically, you will not need to specify axes explicitly. Rather, predefined styles take care of this for you:
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1
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\begin{tikzpicture}
\datavisualization [
scientific axes,
x axis={length=3cm, ticks=few},
visualize as smooth line
]
data [format=function] {
var x : interval [-1.5:1.5] samples 7;
func y = \value x*\value x;
};
\end{tikzpicture}
\begin{tikzpicture}
\datavisualization [
scientific axes=clean,
x axis={length=3cm, ticks=few},
all axes={grid},
visualize as smooth line
]
data [format=function] {
var x : interval [-1.5:1.5] samples 7;
func y = \value x*\value x;
};
\end{tikzpicture}
Section 77 explains in more detail how axes, ticks, and grid lines can be chosen and configured.
75.4
Concept: Visualizers
Data points and axes specify what is visualized and where. A visualizer specifies how they are visualized.
One of the most common visualizers is a line visualizer which connects the positions of the data points in
the plane using a line. Another common visualizer is the scatter plot visualizer where small marks are drawn
at the positions of the data points. More advanced visualizers include, say, box plot visualizers or pie chart
visualizers.
1
\begin{tikzpicture}
\datavisualization [
scientific axes=clean,
x axis={length=3cm, ticks=few},
visualize as smooth line
]
data [format=function] {
var x : interval [-1.5:1.5] samples 7;
func y = \value x*\value x;
};
\end{tikzpicture}
1
\begin{tikzpicture}
\datavisualization [
scientific axes=clean,
x axis={length=3cm, ticks=few},
visualize as scatter
]
data [format=function] {
var x : interval [-1.5:1.5] samples 7;
func y = \value x*\value x;
};
\end{tikzpicture}
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1.5
1
0.5
0
−1
0
2
1.5
1
0.5
0
−1
0
Section 78 provides more information on visualizers as well as reference lists.
75.5
Concept: Style Sheets and Legends
A single data visualizations may use more than one visualizer. For instance, if you wish to create a plot
containing several lines, a separate visualizer is used for each line. In this case, two problems arise:
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1. You may wish to make it easy for the reader to differentiate between the different visualizers. For
instance, one line should be black, another should be red, and another blue. Alternatively, you might
wish one line to be solid, another to be dashed, and a third to be dotted.
Specifying such styles is trickier than one might expect; experience shows that many plots use ill-chosen
and inconsistent styling. For this reason, the data visualization introduces the notion of style sheets
for visualizers and comes with some well-designed predefined style sheets.
2. You may wish to add information concerning what the different visualizers represent. This is typically
done using a legend, but it is even better to add labels directly inside the visualization. Both approaches
are supported.
An example where three functions are plotted and a legend is added is shown below. Two style sheets
are used so that both the coloring and the dashing is varied.
1
0.5
sin x
cos x
tan x
0
−0.5
−1
−1
0
1
2
3
4
\begin{tikzpicture}[baseline]
\datavisualization [ scientific axes=clean,
y axis=grid,
visualize as smooth line/.list={sin,cos,tan},
style sheet=strong colors,
style sheet=vary dashing,
sin={label in legend={text=$\sin x$}},
cos={label in legend={text=$\cos x$}},
tan={label in legend={text=$\tan x$}},
data/format=function ]
data [set=sin] {
var x : interval [-0.5*pi:4];
func y = sin(\value x r);
}
data [set=cos] {
var x : interval [-0.5*pi:4];
func y = cos(\value x r);
}
data [set=tan] {
var x : interval [-0.3*pi:.3*pi];
func y = tan(\value x r);
};
\end{tikzpicture}
Section 79 details style sheets and legends.
75.6
Usage
Inside a Tik Z picture you can use the \datavisualization command to create a data visualization. You
can use this command several times in a picture to create pictures containing multiple data visualizations.
\datavisualization[hdata visualization optionsi]hdata specificationi;
This command is available only inside a {tikzpicture} environment.
The hdata visualization optionsi are used to configure the data visualization, that is, how the data is to
be depicted. The options are executed with the path prefix /tikz/data visualization. This means
that normal Tik Z options like thin or red cannot be used here. Rather, a large number of options
specific to data visualizations are available.
As a minimum, you should specify at least two options: First, you should use an option that selects
an axis system that is appropriate for your plot. Typical possible keys are school book axes or
scientific axes, detailed information on them can be found in Section 77.
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Second, you use an option to select how the data should be visualized. This is done using a key like
visualize as line which will, as the name suggests, visualize the data by connecting data points in
the plane using a line. Similarly, visualize as smooth cycle will try to fit a smooth cycle through
the data points. Detailed information on possible visualizers can be found in Section 78.
Following these options, the hdata specificationi is used to provide the actual to-be-visualized data. The
syntax is somewhat similar to commands like \path: The hdata specificationi is a sequence of keywords
followed by local options and parameters, terminated with a semicolon. (Indeed, like for the \path
command, the hdata visualizers optionsi need not be specified at the beginning, but additional option
surrounded by square brackets may be given anywhere inside the hdata specificationi.)
The different possible keywords inside the hdata specificationi are explained in the following.
\datavisualization . . . data[hoptionsi]{hinline datai} . . . ;
This command is used to specify data for the data visualization. It can be used several times inside a
single visualization and each time the to-be-read data may have a different format, but the data will be
visualized as if it have been specified inside a single data command.
The behaviour of the data command depends on whether the hinline datai is present. If it is not present,
the hoptionsi must be used to specify a source file from which the data is read; if the hinline datai is
present no file will be used, instead the data should directly reside inside the TEX-file and be given
between the curly braces surrounding the hinline datai.
The hoptionsi are executed with the prefix /pgf/data. The following options are always available:
(no default, initially empty)
/pgf/data/read from file=hfilenamei
If you set the source attribute to a non-empty hfilenamei, the data will be read from this file. In
this case, no hinline datai may be present, not even empty curly braces should be provided.
\datavisualization ...
data [read from file=file1.csv]
data [read from file=file2.csv];
The other way round, if read from file is empty, the data must directly follow as hinline datai.
\datavisualization ...
data {
x, y
1, 2
2, 3
};
The second important key is format, which is used to specify the data format:
(no default, initially table)
/pgf/data/format=hformati
Use this key to locally set the format used for parsing the data, see Section 76 for a list of predefined
formats.
The default format is the table-format, also known as “comma-separated values.” The first line
contains names of attributes separated by commas, all following lines constitute a data point where
the attributes are given by the comma-separated values in that line.
Presetting attributes. Normally, the inline data or the external data contains for each data point
the values of the different attributes. However, sometimes you may also wish to set an attribute to
a fixed value for all data points of a data set. Suppose, for instance, that you have to source files
experiment007.csv and experiment023.csv and you would like that for all data points of the first
file the attribute /data point/experiment id is set to 7 while for the data points of the second file
they are set to 23. In this case, you can specify the desired settings using an absolute path inside the
hoptionsi. The effect will be local to the current data command:
\datavisualization...
data [/data point/experiment=7, read from file=experiment007.csv]
data [/data point/experiment=23, read from file=experiment023.csv];
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0
1
2
\tikz
\datavisualization [school book axes, visualize as line]
data [/data point/x=1] {
y
1
2
}
data [/data point/x=2] {
y
2
0.5
};
Setting options for multiple data commands. You may wish to generally set the format once and
for all. This can be done by using the following key:
(style, no value)
/tikz/every data
This key is executed for every data command.
Another way of passing options to multiple data commands is to use the following facility: Whenever
an option with the path /tikz/data visualization/data is used, the path will be remapped to
/pgf/data. This means, in particular, that you can pass an option like data/format=table to the
\datavisualization command to set the data format for all data commands of the data visualization.
Parsing inline data. When you specify data inline, TEX needs to read the data “line-by-line,” while
TEX normally largely ignores end-of-line characters. For this reason, the data visualization system
temporarily changes the meaning of the end-of-line character. This is only possible if TEX has not
already processed the data in some other way (namely as the parameter to some macro).
The bottom line is that you cannot use inline data when the whole \datavisualization command
is passed as a parameter to some macro that is not setup to handle “fragile” code. For instance, in a
beamer frame you need to add the fragile option when a data visualization contains inline data.
The problem does not arise when an external data source is specified.
\datavisualization . . . data point[hoptionsi] . . . ;
This command is used to specify data a single data point. The hoptionsi are simply executed with the
path /data point and then a data point is created. This means that inside the hoptionsi you just
specify the values of all attributes in key-value syntax.
\tikz \datavisualization [school book axes, visualize as line]
data point [x=1, y=1]
data point [x=1, y=2]
data point [x=2, y=2]
data point [x=2, y=0.5];
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2
/tikz/data visualization/data point=hoptionsi
(no default)
This key is the “key version” of the previous command. The difference is that this key can be used
internally inside styles.
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1
2
\tikzdatavisualizationset{
horizontal/.style={
data point={x=#1, y=1}, data point={x=#1, y=2}},
}
\tikz \datavisualization
[ school book axes, visualize as line,
horizontal=1,
horizontal=2 ];
\datavisualization . . . data group[hoptionsi]{hnamei}+={hdata specificationsi} . . . ;
You can store a whole hdata specificationi in a data group. This allows you to reuse data in multiple
places without having to write the data to an external file.
The syntax of this command comes in the following three variants:
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• data group [hoptionsi] {hnamei} = {hdata specificationsi}
• data group [hoptionsi] {hnamei} += {hdata specificationsi}
• data group [hoptionsi] {hnamei}
In the first case, a new data group called hnamei is created (an existing data group of the same name
will be erased) and the following hdata specificationsi is stored in this data group. The data group will
not be fed to the rendering pipeline, but it is parsed at this point as if it were. The defined data group
is defined globally, so you can used it in subsequent visualizations. The hoptionsi are saved with the
parsed hdata specificationsi.
In the second case, an already existing data group is extended by adding the hdata specificationsi to it.
In the third case (detected by noting that the hnamei is neither followed by an equal sign nor a plus
sign), the contents of the previously defined data group hnamei is inserted. The hoptionsi are also
executed.
Let is now first create a data group. Note that nothing is drawn since the “dummy” data visualization
is empty and used only for the definition of the data group.
\tikz \datavisualization data group {points} = {
data {
x, y
0, 1
1, 2
2, 2
5, 1
2, 0
1, 1
}
};
We can now use this data in different plots:
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\tikz \datavisualization [school book axes,
visualize as line] data group {points};
\qquad
\tikz \datavisualization [scientific axes=clean, visualize as line] data group {points};
\datavisualization . . . scope[hoptionsi]{hdata specificationi} . . . ;
Scopes can be used to nest hierarchical data sets. The hoptionsi will be executed with the path /pgf/data and will only apply to the data sets specified inside the hdata specificationi, which may contain
data or scope commands once more:
\datavisualization...
scope [/data point/experiment=7]
{
data [read from file=experiment007-part1.csv]
data [read from file=experiment007-part2.csv]
data [read from file=experiment007-part3.csv]
}
scope [/data point/experiment=23, format=foo]
{
data [read from file=experiment023-part1.foo]
data [read from file=experiment023-part2.foo]
};
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\datavisualization . . . info[hoptionsi]{hcodei} . . . ;
This command will execute normal Tik Z hcodei at the end of a data visualization. The hoptionsi are
executed with the normal path /tikz/.
The only difference between this command and just giving the hcodei directly following the data visualization is that inside the hcodei following an info command you still have access to the coordinate
system of the data visualization. In sharp contrast, Tik Z code given after a data visualization can no
longer access this coordinate system.
extremal point
1
0
1
2
\begin{tikzpicture}[baseline]
\datavisualization [ school book axes, visualize as line ]
data [format=function] {
var x : interval [-0.1*pi:2];
func y = sin(\value x r);
}
info {
\draw [red] (visualization cs: x={(.5*pi)}, y=1) circle [radius=1pt]
node [above,font=\footnotesize] {extremal point};
};
\end{tikzpicture}
As can be seen, inside a data visualization a special coordinate system is available:
Coordinate system visualization
As for other coordinate systems, the syntax is (visualization cs:hlist of attribute-value pairsi).
The effect is the following: For each pair hattributei=hvaluei in the hlisti the key /data
point/hattributei is set to hvaluei. Then, it is computed where the resulting data point “would lie”
on the canvas (however, no data point is passed to the visualizers).
\datavisualization . . . info’[hoptionsi]{hcodei} . . . ;
This command works like info, only the hcodei will be executed just before the visualization is done.
This allows you to draw things behind the visualization.
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0
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2
\begin{tikzpicture}[baseline]
\datavisualization [ school book axes, visualize as line ]
data [format=function] {
var x : interval [-0.1*pi:2];
func y = sin(\value x r);
}
info’ {
\fill [red] (visualization cs: x={(.5*pi)}, y=1) circle [radius=2mm];
};
\end{tikzpicture}
Predefined node data visualization bounding box
This rectangle node stores a bounding box of the data visualization that is currently being constructed.
This node can be useful inside info commands or when labels need to be added.
Predefined node data bounding box
This rectangle node is similar to data visualization bounding box, but it keeps track only of the actual data. The spaces needed for grid lines, ticks, axis labels, tick labels, and other all other information
that is not part of the actual data is not part of this box.
75.7
Advanced: Executing User Code During a Data Visualization
The following keys can be passed to the \datavisualization command and allow you to execute some code
at some special time during the data visualization process. For details of the process and on which signals
are emitted when, see Section 81.
/tikz/data visualization/before survey=hcodei
(no default)
The hcodei is passed to the before survey method of the data visualization object and then executed
at the appropriate time (see Section 81 for details).
The following commands work likewise:
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/tikz/data visualization/at start survey=hcodei
(no default)
/tikz/data visualization/at end survey=hcodei
(no default)
/tikz/data visualization/after survey=hcodei
(no default)
/tikz/data visualization/before visualization=hcodei
(no default)
/tikz/data visualization/at start visualization=hcodei
(no default)
/tikz/data visualization/at end visualization=hcodei
(no default)
/tikz/data visualization/after visualization=hcodei
(no default)
75.8
Advanced: Creating New Objects
You will need the following key only when you wish to create new rendering pipelines from scratch – instead
of modifying an existing pipeline as you would normally do. In the following it is assumed that you are
familiar with the concepts of Section 81.
/tikz/data visualization/new object=hoptionsi
(no default)
This key serves two purposes:
1. This method makes it easy to create a new object as part of the rendering pipeline, using hoptionsi
to specify arguments rather that directly calling \pgfoonew. Since you have the full power of the
keys mechanism at your disposal, it is easy, for instance, to control whether or not parameters to
the constructor are expanded or not.
2. The object is not created immediately, but only just before the visualization starts. This allows
you to specify that an object must be created, but the parameter values of for its constructor
may depend on keys that are not yet set. A typical application is the creating of an axis object:
When you say scientific axes, the new object command is used internally to create two objects
representing these axes. However, keys like x={length=5cm} can only later be used to specify the
parameters that need to be passed to the constructor of the objects.
The following keys may be used inside the hoptionsi:
/tikz/data visualization/class=hclass namei
(no default)
The class of the to-be-created object.
/tikz/data visualization/when=hphase namei
(no default, initially before survey)
This key is used to specify when the object is to be created. As described above, the object is not
created immediately, but at some time during the rendering process. You can specify any of the
phases defined by the data visualization object, see Section 81 for details.
/tikz/data visualization/store=hkey namei
(no default)
If the hkey namei is not empty, once the object has been created, a handle to the object will be
stored in hkey namei. If a handle is already stored in hkey namei, the object is not created twice.
/tikz/data visualization/before creation=hcodei
(no default)
This code is executed right before the object is finally created. It can be used to compute values
that are then passed to the constructor.
/tikz/data visualization/after creation=hcodei
(no default)
This code is executed right after the object has just been created. A handle to the just-created
object is available in \tikzdvobj.
(no default)
/tikz/data visualization/arg1=hvaluei
The value to be passed as the first parameter to the constructor. Similarly, the keys arg2 to arg8
specify further parameters passed. Naturally, only as many arguments are passed as parameters
are set. Here is an example:
767
\tikzdatavisualizationset{
new object={
class = example class,
arg1 = foo,
arg2 = \bar
}
}
causes the following object creation code to be executed later on:
\pgfoonew \tikzdvobj=new example class(foo,\bar)
Note that you key mechanisms like .expand once to pass the value of a macro instead of the macro
itself:
\tikzdatavisualizationset{
new object={
class
= example class,
arg1
= foo,
arg2/.expand once = \bar
}
}
Now, if \bar is set to This \emph{is} it. at the moment to object is created later on, the
following object creation code is executed:
\pgfoonew \tikzdvobj=new example class(foo,This \emph{is} it)
/tikz/data visualization/arg1 from key=hkeyi
(no default)
Works like the arg1, only the value that is passed to the constructor is the current value of the
specified hkeyi at the moment when the object is created.
\tikzdatavisualizationset{
new object={
class
= example class,
arg1 from key
= /tikz/some key
}
}
\tikzset{some key/.initial=foobar}
causes the following to be executed:
\pgfoonew \tikzdvobj=new example class(foobar)
Naturally, the keys arg2 from key to arg8 from key are also provided.
/tikz/data visualization/arg1 handle from key=hkeyi
(no default)
Works like the arg1 from key, only the key must store an object and instead of the object a handle
to the object is passed to the constructor.
768
76
Providing Data for a Data Visualization
76.1
Overview
The data visualization system needs a stream of data points as input. These data points can be directly
generated by repeatedly calling the \pgfdatapoint command, but usually data is available in some special
(text) format and one would like to visualize this data. The present section explains how data in some
specific format can be fed to the data visualization system.
This section starts with an explanation of the main concepts. Then, the standard formats are listed in
the reference section. It is also possible to define new formats, but this an advanced concept which requires
an understanding of some of the internals of the parsing mechanism, explained in Section 76.5, and the usage
of a rather low-level command, explained in Section 76.6.
76.2
Concepts
For the purposes of this section, let call a data format some standardized way of writing down a list of data
points. A simple example of a data format is the csv format (the acronym stands for comma separated
values), where each line contains a data point, specified by values separated by commas. A different format
is the key–value format, where data points are specified by lists of key–value pairs. A far more complex
format is the pdb-format used by the protein database to describe molecules.
The data visualization system does not use any specific format. Instead, whenever data is read by the
data visualization system, you must specify a format parser (or it is chosen automatically for you). It is
the job of the parser to read (parse) the data lines and to turn them into data points, that is, to setup
appropriate subkeys of /data point/.
To give a concrete example, suppose a file contains the following lines:
x,
0,
1,
1,
0,
y,
0,
1,
1,
1,
z
0
0
0.5
0.5
This file is in the csv-format. This format can be read by the table parser (which is called thus, rather
than “csv,” since it can also read files in which the columns are separated by, say, a semicolon or a space).
The table format will then read the data and for each line of the data, except for the headline of course, it
will produce one data point. For instance, for the last data point the key /data point/x will be set to 0,
the key /data point/y will be set to 1, and the key /data point/z will be set to 0.5.
All parsers are basically line-oriented. This means that, normally, each line in the input data should
contain one data point. This rule may not always apply, for instance empty lines are typically ignored and
sometimes a data point may span several lines, but deviating from this “one data point per line” rule makes
parsers harder to program.
76.3
Reference: Build-In Formats
The following format is the default format, when no format=... is specified.
Format table
This format is used to parse data that is formatted in the following manner: Basically, each line consists
of values that are separated by a separator like a comma or a space. The values are stored in different
attributes, that is, subkeys of /data point like /data point/x. In order to decide which attribute is
chosen for a give value, the headline is important. This is the first non-empty line of a table. It is
formatted in the same way as normal data lines (value separated by the separator), but the meaning of
the values is different: The first value in the headline is the name of the attribute where the first values
in the following lines should go each time. Similarly, the second value in the headline is the name of the
attribute for the second values in the following lines, and so on.
A simple example is the following:
angle, radius
0, 1
45, 2
90, 3
135, 4
769
The headline states that the values in the first column should be stored in the angle attribute (/data
point/angle to be precise) and that the values in the second column should be stored in the radius
attribute. There are four data points in this data set.
The format will tolerate too few or too many values in a line. If there are less values in a line than in
the headline, the last attributes will simply be empty. If there are more values in a line than in the
headline, the values are stored in attributes called /data point/attribute hcolumn number i, where
the first value of a line gets hcolumn number i equal to 1 and so on.
The table format can be configured using the following options:
/pgf/data/separator=hcharacter i
(no default, initially ,)
Use this key to change which character is used to separate values in the headline and in the data lines.
To set the separator to a space, either set this key to an empty value or say separator=\space.
Note that you must surround a comma by curly braces if you which to (re)set the separator character
to a space.
2
1
0
1
2
3
\begin{tikzpicture}
\datavisualization [school book axes, visualize as line]
data [separator=\space] {
x y
0 0
1 1
2 1
3 0
}
data [separator=;] {
x; y; z
3; 1; 0
2; 2; 0
};
\end{tikzpicture}
(no default)
/pgf/data/headline=hheadlinei
When this key is set to a non-empty value, the value of hheadlinei is used as the headline and the
first line of the data is treated as a normal line rather than as a headline.
1
0
1
2
3
\begin{tikzpicture}
\datavisualization [school book axes, visualize as line]
data [headline={x, y}] {
0, 0
1, 1
2, 1
3, 0
};
\end{tikzpicture}
Format named
Basically, each line of the data must consist of a comma-separated sequence of attribute–values pairs
like x=5, lo=500. This will cause the attribute /data point/x to be set to 5 and /data point/lo to
be set to 500.
1
0
1
2
3
\begin{tikzpicture}
\datavisualization [school book axes, visualize as line]
data [format=named] {
x=0, y=0
x=1, y=1
x=2, y=1
x=3, y=0
};
\end{tikzpicture}
However, instead of just specifying a single value for an attribute as in x=5, you may also specify a
whole set of values as in x={1,2,3}. In this case, three data points will be created, one for each value
770
in the list. Indeed, the \foreach statement is used to iterate over the list of values, so you can write
things like x={1,...,5}.
It is also permissible to specify lists of values for more than one attribute. In this case, a data point is
created for each possible combination of values in the different lists:
15
\tikz \datavisualization
[scientific axes=clean,
visualize as scatter/.list={a,b,c},
style sheet=cross marks]
data [format=named] {
x=0,
y={1,2,3},
set=a
x={2,3,4}, y={3,4,5,7},
set=b
x=6,
y={5,7,...,15},
set=c
};
12.5
10
7.5
5
2.5
0
1
2
3
4
5
6
Format TeX code
This format will simply execute each line of the data, each of which should contain some normal TeX
code. Note that at the end of each line control returns to the format handler, so for instance the
arguments of a command may not be spread over several lines. However, not each line needs to produce
a data point.
1
0
1
76.4
2
3
\begin{tikzpicture}
\datavisualization [school book axes, visualize as line]
data [format=TeX code] {
\pgfkeys{/data point/.cd,x=0, y=0} \pgfdatapoint
\pgfkeys{/data point/.cd,x=1, y=1} \pgfdatapoint
\pgfkeys{/data point/x=2}
\pgfdatapoint
\pgfkeyssetvalue{/data point/x}{3}
\pgfkeyssetvalue{/data point/y}{0} \pgfdatapoint
};
\end{tikzpicture}
Reference: Advanced Formats
Tik Z Library datavisualization.formats.functions
\usetikzlibrary{datavisualization.formats.functions} % LATEX and plain TEX
\usetikzlibrary[datavisualization.formats.functions] % ConTEXt
This library defines the formats described in the following, which allow you to specify the data points
indirectly, namely via a to-be-evaluated function.
Format function
This format allows you to specify a function that is then evaluated in order to create the desired
data points. In other words, the data lines do not contain the data itself, but rather a functional
description of the data.
The format used to specify the function works as follows: Each nonempty line of the data should
contain at least one of either a variable declaration or a function declaration. A variable declaration
signals that a certain attribute will range over a given interval. The function declarations will then,
later, be evaluated for values inside this interval. The syntax for a variable declaration is one of
the following:
1. var hvariablei :
2. var hvariablei :
3. var hvariablei :
interval[hlow i:hhighi] samples hnumber i;
interval[hlow i:hhighi] step hstepi;
{hvaluesi};
In the first case, if the optional samples part is missing, the number of samples is taken from the
value stored in the following key:
/pgf/data/samples=hnumber i
(no default, initially 25)
Sets the number of samples to be used when no sample number is specified.
771
The meaning of declaring a variable declaration to range over an interval is that the attribute named hvariablei, that is, the key /data point/hvariablei, will range over the interval
[hlow i, hhighi]. If the number of samples is given (directly or indirectly), the interval is evenly
divided into hnumber i many points and the attribute is set to each of these values. Similarly, when
a hstepi is specified, this stepping is used to increase hlow i iteratively up to the largest value that
is still less or equal to hhighi.
The meaning of declaring a variable using a list of hvaluesi is that the variable will simply iterate
over the values using \foreach.
You can specify more than one variable. In this case, each variable is varied independently of the
other variables. For instance, if you declare an x-variable to range over the interval [0, 1] in 25 steps
and you also declare a y-variable to range over the same interval, you get a total of 625 value pairs.
The variable declarations specify which (input) variables will take which values. It is the job of the
function declarations to specify how some additional attributes are to be computed. The syntax of
a function declaration is as follows:
func hattributei = hexpressioni;
The meaning of such a declaration is the following: For each setting of the input variables (the
variables specified using the var declaration), evaluate the hexpressioni using the standard mathematical parser of Tik Z. The resulting value is then stored in /data point/hattributei.
Inside hexpressioni you can reference data point attributes using the following command, which is
only defined inside such an expression:
\value{hvariablei}
This expands to the current value of the key /data point/hvariablei.
There can be multiple function declarations in a single data specification. In this case, all of these
functions will be evaluated for each setting of input variables.
\tikz
\datavisualization [school book axes, visualize as smooth line]
data [format=function] {
var x : interval [-1.5:1.5];
2
1
func y = \value x * \value x;
};
−1
−2
0
1
0
2
4
6
\tikz \datavisualization [
school book axes,
all axes={unit length=5mm, ticks={step=2}},
visualize as smooth line]
data [format=function] {
var t : interval [0:2*pi];
−2
func x = \value t * cos(\value t r);
func y = \value t * sin(\value t r);
};
−4
0.15
0.10
0.05
0.00
−0.05
−0.10
−0.15
0◦
10◦
20◦
30◦
40◦
50◦
\tikz \datavisualization [
scientific axes=clean,
y axis={ticks={style={
/pgf/number format/fixed,
/pgf/number format/fixed zerofill,
/pgf/number format/precision=2}}},
x axis={ticks={tick suffix=${}^\circ$}},
visualize as smooth line/.list={1,2,3,4,5,6},
style sheet=vary hue]
data [format=function] {
var set : {1,...,6};
var x : interval [0:50];
func y = sin(\value x * (\value{set}+10))/(\value{set}+5);
};
772
76.5
Advanced: The Data Parsing Process
Whenever data is fed to the data visualization system, it will be handled by the \pgfdata command, declared
in the datavisualization module. The command is both used to parse data stored in external sources
(that is, in external files or which is produced on the fly by calling an external command) as well as data
given inline. A data format does not need to know whether data comes from a file or is given inline, the
\pgfdata command will take care of this.
Since TEX will always read files in a line-wise fashion, data is always fed to data format parsers in such a
fashion. Thus, even it would make more sense for a format to ignore line-breaks, the parser must still handle
data given line-by-line.
Let us now have a look at how \pgfdata works.
\pgfdata[hoptionsi]{hinline datai}
This command is used to feed data to the visualization pipeline. This command can only be used when
a data visualization object has been properly setup, see Section 75.
Basic options. The \pgfdata command may be followed by hoptionsi, which are executed with the
path /pgf/data/. Depending on these options, the hoptionsi may either be followed by hinline datai
or, alternatively, no hinline datai is present and the data is read from an external source.
The first important option is hsourcei, which governs which of these two alternatives applies:
(no default, initially empty)
/pgf/data/read from file=hfilenamei
If you set the read from file attribute to a non-empty hfilenamei, the data will be read from this
file. In this case, no hinline datai may be present, not even empty curly braces should be provided.
If read from file is empty, the data must directly follow as hinline datai.
% Data is read from two external files:
\pgfdata[format=table, read from file=file1.csv]
\pgfdata[format=table, read from file=file2.csv]
% Data is given inline:
\pgfdata[format=table]
{
x, y
1, 2
2, 3
}
(no value)
/pgf/data/inline
This is a shorthand file read from file={}. You can add this to make it clear(er) to the reader
that data follows inline.
The second important key is format, which is used to specify the data format:
(no default, initially table)
/pgf/data/format=hformati
Use this key to locally set the format used for parsing the data. The hformati must be a format
that has been previously declared using the \pgfdeclaredataformat command. See the reference
section for a list of the predefined formats.
In case all your data is in a certain format, you may wish to generally set the above key somewhere at
the beginning of your file. Alternatively, you can use the following style to setup the format key and
possibly further keys concerning the data format:
(style, no value)
/pgf/every data
This style is executed by \pgfdata before the hoptionsi are parsed.
Note that the path of this key is just /pgf/, not /pgf/data/. Also note that Tik Z internally
sets the value of this key up in such a way that the keys /tikz/every data and also /tikz/data
visualization/every data are executed. The bottom line of this is that when using Tik Z, you
should not set this key directly, set /tikz/every data instead.
773
Gathering of the data. Once the data format and the source have been decided upon, the data is
“gathered.” During this phase the data is not actually parsed in detail, but just gathered so that it can
later be parsed during the visualization. There are two different ways in which the data is gathered:
• In case you have specified an external source, the data visualization object is told (by means of
invoking the add data method) that it should (later) read data from the file specified by the
source key using the format specified by the format key. The file is not read at this point, but
only later during the actual visualization.
• Otherwise, namely when data is given inline, depending on which format is used, some catcodes
get changed. This is necessary since TEX’s special characters are often not-so-special in a certain
format.
Independently of the format, the end-of-line character (carriage return) is made an active character.
Finally, the hinline datai is then read as a normal argument and the data visualization object is
told that later on it should parse this data using the given format parser. Note that in this case
the data visualization object must store the whole data internally.
In both cases the “data visualization object” is the object stored in the /pgf/data visualization/obj
key.
Parsing of the data. During the actual data visualization, all code that has been added to the data
visualization object by means of the add data method is executed several times. It is the job of this
code to call the \pgfdatapoint method for all data points present in the data.
When the \pgfdata method calls add data, the code that is passed to the data visualization object is
just a call to internal macros of \pgfdata, which are able to parse the data stored in an external file or
in the inlined data. Independently of where the data is stored, these macros always do the following:
1. The catcodes are setup according to what the data format requires.
2. Format-specific startup code gets called, which can initialize internal variables of the parsing process. (The catcode changes are not part of the startup code since in order to read inline data
\pgfdata must be able to setup to temporarily setup the catcodes needed later on by the parsers,
but since no reading is to be done, no startup code should be called at this point.)
3. For each line of the data a format-specific code handler, which depends on the data format, is
called. This handler gets the current line as input and should call \pgfdatapoint once for each
data point that is encoded by this line (a line might define multiple data points or none at all).
Empty lines are handled by special format-specific code.
4. At the end, format-specific end code is executed.
For an example of how this works, see the description of the \pgfdeclaredataformat command.
Data sets. There are three options that allow you to create data sets. Such a data set is essentially a
macro that stores a pre-parsed set of data that can be used multiple times in subsequent visualizations
(or even in the same visualization).
(no default)
/pgf/data/new set=hnamei
Creates an empty data set called hnamei. If a data set of the same name already exists, it is
overwritten and made empty. Data sets are global.
(no default)
/pgf/data/store in set=hnamei
When this key is set to any non-empty hnamei and if this hnamei has previously been used with the
new set key, then the following happens: For the current \pgfdata command, all parsed data is
not passed to the rendering pipeline. Instead, the parsed data is appended to the data set hnamei.
This includes all options parsed to the \pgfdata command, which is why neither this key nor the
previous key should be passed as options to a \pgfdata command.
(no default)
/pgf/data/use set=hnamei
This works similar to read from file. When this key is used with a \pgfdata command, no inline
data may follow. Instead, the data stored in the data set hnamei is used.
774
76.6
Advanced: Defining New Formats
In order to define a new data format you can use the following command, which is basic layer command
defined in the module datavisualization:
\pgfdeclaredataformat{hformat namei}{hcatcode codei}{hstartup codei}{hline argumentsi}
{hline codei}{hempty line codei}{hend codei}
This command defines a new data format called hformat namei, which can subsequently be used in the
\pgfdata command. (The Tik Z’s data maps directly to \pgfdata, so the following applies to Tik Z as
well.)
As explained in the description of the \pgfdata command, when data is being parsed that is formatted
according to hformat namei, the following happens:
1. The hcatcode codei is executed. This code should just contain catcode changes. The hcatcode codei
will also be executed when inline data is read.
2. Next, the hstartup codei is executed.
3. Next, for each non-empty line of the data, the line is passed to a macro whose argument list is given
by hline argumentsi and whose body is given by hline codei. The idea is that you can use TEX’s
powerful pattern matching capabilities to parse the non-empty lines. See also the below example.
4. Empty lines are not processed by the hline codei, but rather by the hempty line codei. Typically,
empty lines can simply be ignored and in this case you can let this parameter be empty.
5. At the end of the data, the hend codei is executed.
As an example, let us now define a simple data format for reading files formatted in the following
manner: Each line should contain a coordinate pair as in (1.2,3.2), so two numbers separated by a
comma and surrounded by parentheses. To make things more interesting, suppose that the hash mark
symbol can be used to indicate comments. Here is an example of some data given in this format:
# This is some data formatted according to the "coordinates" format
(0,0)
(0.5,0.25)
(1,1)
(1.5,2.25)
(2,4)
A format parser for this format could be defined as follows:
\pgfdeclaredataformat{coordinates}
% First comes the catcode argument. We turn the hash mark into a comment character.
{\catcode‘\#=14\relax}
% Second comes the startup code. Since we do not need to setup things, we can leave
% it empty. Note that we could also set it to something like \begingroup, provided we
% put an \endgroup in the end code
{}
% Now comes the arguments for non-empty lines. Well, these should be of the form
% (#1,#2), so we specify that:
{(#1,#2)}
% Now we must do something with a line of this form. We store the #1 argument in
% /data point/x and #2 in /data point/y. Then we call \pgfdatapoint to create a data point.
{
\pgfkeyssetvalue{/data point/x}{#1}
\pgfkeyssetvalue{/data point/y}{#2}
\pgfdatapoint
}
% We ignore empty lines:
{}
% And we also have no end-of-line code.
{}
This format could now be used as follows:
775
\begin{tikzpicture}
\datavisualization[school book axes, visualize as smooth line]
data [format=coordinates] {
# This is some data formatted according
# to the "coordinates" format
(0,0)
(0.5,0.25)
(1,1)
(1.5,2.25)
(2,4)
};
\end{tikzpicture}
776
77
Axes
77.1
Overview
When a data point is visualized, the most obvious way of creating a visual representation of its many
attributes is to vary where the data point is shown. The data visualization system uses axes to turn data
point attributes into positions on a page. The simplest – and most common – use of axes is to vary the
horizontal position of data points according to one attribute and to vary the vertical position according to
another attribute. In contrast, in a polar plot one attribute dictates the distance of the data point from the
origin and another attribute describes the angle. From the data visualization engine’s point of view, in both
cases two axes are involved.
In addition to specifying how the value of a certain attribute is converted into a displacement on the page,
an axis is also typically (but not always) visualized (“drawn”) somewhere on the page. In this case, it is also
customary to add a visual representation on this axis of which attribute values correspond to which positions
on the page – something commonly known as ticks. Similar to ticks, grid lines also indicate positions where
a certain attribute has a certain value, but instead of just indicating a single position on an axis, a grid line
goes through all points that share an attribute value.
In the following, in Section 77.2 we first have a look at how axes can be defined and configured. As
you will see, a lot of powerful configurations are available, but you will rarely define and configure an axis
from scratch. Rather, it is more common to use a preconfigured axis instead. Section 77.3 introduces axis
systems, which are predefined bundles of axes. You can define your own axis systems, but, again, in most
cases it will suffice to just use one of the many preconfigured axis systems and use a few options to configure
it so that it fits your need. Section 77.4 explains how ticks and grid lines can be configured. Again, several
layers of options allow you to configure the way ticks look and where they are placed in great detail.
This section documents the standard axis systems that are always available. For polar axis systems, a
special library needs to be loaded, which is documented in Section 80.
77.2
Basic Configuration of Axes
Inside the data visualization system, an axis is roughly a “systematic, named way of mapping an attribute
to a position on a page”. For instance, the classical “x-axis” is the “systematic way of mapping the value of
the x attribute of data points to a horizontal position on the page”. An axis is not its visual representation
(such as the horizontal line with the ticks drawn to represent the x-axis), but a visual representation can be
created once an axis has been defined.
The transformation of an attribute value (such as the value 1000000000 for the x attribute) to a specific
displacement of the corresponding data point on the page involves two steps:
1. First, the range of possible values such as [−5.6 · 1012 , 7.8 · 1012 ] must be mapped to a “reasonable”
interval such as [0cm, 5cm] or [0◦ , 180◦ ]. Tik Z’s drawing routines will only be able to cope with values
from such a “reasonable” interval.
2. Second, the values from the reasonable interval must be mapped to a transformation.
The first step is always the same for all axes, while the second requires different strategies. For this reason,
the command new axis base is used to create a “basic” axis that has a “scaling mapper”, whose job it is to
map the range of values of a specific attribute to a reasonable interval, but such a basic axis does not define
an actual transformation object. For this second step, additional objects such as a linear transformer
need to be created separately.
77.2.1
Usage
To create an axis, the key new axis base is used first. Since this key does not create a transformation
object, users typically do not use this key directly. Rather, it is used internally by other keys that create
“real” axes. These keys are listed in Section 77.2.8.
/tikz/data visualization/new axis base=haxis namei
(no default)
This key defines a new axis for the current data visualization called hnamei. This has two effects:
1. A so called scaling mapper is created that will monitor a certain attribute, rescale it, and map it
to another attribute. (This will be explained in detail in a moment.)
2. The haxis namei is made available as a key that can be used to configure the axis:
777
/tikz/data visualization/haxis name i=hoptionsi
(no default)
This key becomes available once new axis base=metaaxis name has been called. It will
execute the hoptionsi with the path prefix /tikz/data visualization/axis options.
[new axis base=my axis,
my axis={attribute=some attribute}]
3. The haxis namei becomes part of the current set of axes. This set can be accessed through the
following key:
/tikz/data visualization/all axes=hoptionsi
(no default)
This key passes the hoptionsi to all axes inside the current scope, just as if you had written
hsome axis namei=hoptionsi for each hsome axis namei in the current scope, including the
just-created name haxis namei.
There are many hoptionsi that can be passed to a newly created axis. They are explained in the rest of
this section.
Note the new axis base does not cause attributes to be mapped to positions on a page. Rather, special
keys like new Cartesian axis first use new axis base to create an axis and then create an internal object
that performs a linear mapping of the attribute to positions along a vectors.
77.2.2
The Axis Attribute
The first main job of an axis is to map the different values of some attribute to a reasonable interval. To
achieve this, the following options are important (recall that these options are passed to the key whose name
is the name of the axis):
/tikz/data visualization/axis options/attribute=hattributei
(no default)
Specifies that the axis is used to transform the data points according the different values of the key
/data point/hattributei. For instance, when we create a classical two-dimensional Cartesian coordinate
system, then there are two axes called x axis and y axis that monitor the values of the attributes
/data point/x and /data point/y, respectively:
[new axis base=x axis,
new axis base=y axis,
x axis={attribute=x},
y axis={attribute=y}]
In another example, we also create an x axis and a y axis. However, this time, we want to plot the
values of the /data point/time attribute on the x-axis and, say, the value of the height attribute on
the y-axis:
[new axis base=x axis,
new axis base=y axis,
x axis={attribute=time},
y axis={attribute=height}]
During the data visualization, the hattributei will be “monitored” during the survey phase. This means
that for each data point, the current value of /data point/hattributei is examined and the minimum
value of all of these values as well as the maximum value is recorded internally. Note that this works
even when very large numbers like 100000000000 are involved.
Here is a real-life example. The scientific axes create two axes, called x axis and y axis, respectively.
2,000
1,980
1,960
1,940
1,920
1,900
100
150
200
250
\tikz \datavisualization [scientific axes,
x axis={attribute=people, length=2.5cm, ticks=few},
y axis={attribute=year},
visualize as scatter]
data {
year, people
1900, 100
1910, 200
1950, 200
1960, 250
2000, 150
};
778
77.2.3
The Axis Attribute Range Interval
Once an attribute has been specified for an axis, the data visualization engine will start monitoring this
value. This means that before anything actual visualization is done, a “survey phase” is used to determine
the range of values encountered for the attribute for all data points. This range of values results in what
is called the attribute range interval. Its minimum is the smallest value encountered in the data and its
maximum is the largest value.
Even though the attribute range interval is computed automatically and even though you typically do
not need to worry about it, there are some situations where you may wish to set or enlarge the attribute
range interval:
• You may wish to start the interval with 0, even though the range of values contains only positive
values.
• You may wish to slightly enlarge the interval so that, say, the maximum is some “nice” value like 100
or 60.
The following keys can be used to influence the size of the attribute range interval:
/tikz/data visualization/axis options/include value=hlist of valuei
(no default)
This key “fakes” data points for which the attribute’s values are in the comma-separated hlist of valuesi.
For instance, when you write include value=0, then the attribute range interval is guaranteed to
contain 0 – even if the actual data points are all positive or all negative.
100
90
80
70
60
50
40
30
\tikz \datavisualization [scientific axes, all axes={length=3cm},
visualize as line]
data [format=function] {
var x : interval [5:10];
func y = \value x * \value x;
};
5
6
7
8
9
10
100
\tikz \datavisualization [scientific axes, all axes={length=3cm},
visualize as line,
x axis={include value=20},
y axis={include value=0}]
data [format=function] {
var x : interval [5:10];
func y = \value x * \value x;
};
80
60
40
20
0
5 7.5 10 12.5 15 17.5 20
/tikz/data visualization/axis options/min value=hvaluei
(no default)
This key allows you to simply set the minimum value, regardless of which values are present in the actual
data. This key should be used with care: If there are data points for which the attribute’s value is less
than hvaluei, they will still be depicted, but typically outside the normal visualization area. Usually,
saying include value=hvaluei will achieve the same as saying min value=hvaluei, but with less danger
of creating ill-formed visualizations.
/tikz/data visualization/axis options/max value=hvaluei
(no default)
Works like min value.
77.2.4
Scaling: The General Mechanism
The above key allows us specify which attribute should be “monitored”. The next key is used to specify what
should happen with the observed values.
/tikz/data visualization/axis options/scaling=hscaling speci
The hscaling speci must have the following form:
779
(no default)
hs1 i at ht1 i and hs2 i at ht2 i
This means that monitored values in the interval [s1 , s2 ] should be mapped to values the “reasonable”
interval [t1 , t2 ], instead. For instance, we might write
[y axis = {scaling = 1900 at 0cm and 2000 at 5cm}]
in order to map dates between 1900 and 2000 to the dimension interval [0cm, 5cm].
2,000
\tikz \datavisualization
[scientific axes,
x axis={attribute=people, length=2.5cm, ticks=few},
y axis={attribute=year, scaling=1900 at 0cm and 2000 at 5cm},
visualize as scatter]
data {
year, people
1900, 100
1910, 200
1950, 200
1960, 250
2000, 150
};
1,980
1,960
1,940
1,920
1,900
100
150
200
250
So much for the basic idea. Let us now have a detailed look at what happens.
Number format and the min and max keywords. The source values s1 and s2 are typically
just numbers like 3.14 or 10000000000. However, as described in Section 75.2, you can also specify
expressions like (pi/2), provided that (currently) you put them in parentheses.
Instead of a number, you may alternatively also use the two key words min and max for s1 and/or s2 .
In this case, min evaluates to the smallest value observed for the attribute in the data, symmetrically
max evaluates to the largest values. For instance, in the above example with the year attribute ranging
from 1900 to 2000, the keyword min would stand for 1900 and max for 2000. Similarly, for the people
attribute min stands for 100 and max for 250. Note that min and max can only be used for s1 and s2 ,
not for t1 and t2 .
A typical use of the min and max keywords is to say
scaling = min at 0cm and max at 5cm
to map the complete range of values into an interval of length of 5cm.
The interval [s1 , s2 ] need not contain all values that the hattributei may attain. It is permissible that
values are less than s1 or more than s2 .
Linear transformation of the attribute. As indicated earlier, the main job of an axis is to map
values from a “large” interval [s1 , s2 ] to a more reasonable interval [t1 , t2 ]. Suppose that for the current
data point the value of the key /data point/hattributei is the number v. In the simplest case, the
following happens: A new value v 0 is computed so that v 0 = t1 when v = s1 and v 0 = t2 when v = s2
and v 0 is some value in between t1 and t2 then v is some value in between s1 and s2 . (Formally, in this
1
basic case v 0 = t1 + (v − s1 ) st22 −t
−s1 .)
Once v 0 has been computed, it is stored in the key /data point/hattributei/scaled. Thus, the “reasonable” value v 0 does not replace the value of the attribute, but it is placed in a different key. This
means that both the original value and the more “scaled” values are available when the data point is
visualized.
As an example, suppose you have written
[x axis = {attribute = x, scaling=1000 at 20 and 2000 at 30}]
Now suppose that /data point/x equals 1200 for a data point. Then the key /data point/x/scaled
will be set to 22 when the data point is being visualized.
Nonlinear transformations of the attribute. By default, the transformation of [s1 , s2 ] to [t1 , t2 ] is
the linear transformation described above. However, in some case you may be interested in a different
780
kind of transformation: For example, in a logarithmic plot, values of an attribute may range between,
say, 1 and 1000 and we want an axis of length 3cm. So, we would write
[x axis = {attribute = x, scaling=1 at 0cm and 1000 at 3cm}]
Indeed, 1 will now be mapped to position 0cm and 1000 will be mapped to position 3cm. Now, the
value 10 will be mapped to approximately 0.03cm because it is (almost) at one percent between 1 and
1000. However, in a logarithmic plot we actually want 10 to be mapped to the position 1cm rather
than 0.03cm and we want 100 to be mapped to the position 2cm. Such a mapping a nonlinear mapping
between the intervals.
In order to achieve such a nonlinear mapping, the function key can be used, whose syntax is described
in a moment. The effect of this key is to specify a function f : R → R like, say, the logarithm function.
When such a function is specified, the mapping of v to v 0 is computed as follows:
v 0 = t1 + (f (s2 ) − f (v))
t2 − t1
.
f (s2 ) − f (s1 )
The syntax of the function key is described next, but you typically will not call this key directly.
Rather, you will use a key like logarithmic that installs appropriate code for the function key for
you.
/tikz/data visualization/axis options/function=hcodei
(no default)
The hcodei should specify a function f that is applied during the transformation of the interval
[s1 , s2 ] to the interval [t1 , t2 ] in the following way: When the hcodei is called, the macro \pgfvalue
will have been set to an internal representation of the to-be-transformed value v. You can then
call the commands of the math-micro-kernel of the data visualization system, see Section 81.4, to
compute a new value. This new value must once more be stored in \pgfvalue.
The most common use of this key is to say
some axis={function=\pgfdvmathln{\pgfvalue}{\pgfvalue}}
This specifies that the function f is the logarithm function.
3
\tikz \datavisualization
[scientific axes,
x axis={ticks={major={at={1,10,100,1000}}},
scaling=1 at 0cm and 1000 at 3cm,
function=\pgfdvmathln{\pgfvalue}{\pgfvalue}},
visualize as scatter]
data [format=named] {
x={1,100,...,1000}, y={1,2,3}
};
2.5
2
1.5
1
1
10
100
1,000
Another possibility might be to use the square-root function, instead:
3
\tikz \datavisualization
[scientific axes,
x axis={ticks=few,
scaling=1 at 0cm and 1000 at 3cm,
function=\pgfdvmathunaryop{\pgfvalue}{sqrt}{\pgfvalue}},
visualize as scatter]
data [format=named] {
x={0,100,...,1000}, y={1,2,3}
};
2.5
2
1.5
1
0
250 500 750
Default scaling. When no scaling is specified, it may seem natural to use [0, 1] both as the source
and the target interval. However, this would not work when the logarithm function is used as transformations: In this case the logarithm of zero would be computed, leading to an error. Indeed, for a
logarithmic axis it is far more natural to use [1, 10] as the source interval and [0, 1] as the target interval.
781
For these reasons, the default value for the scaling that is used when no value is specified explicitly
can be set using a special key:
/tikz/data visualization/axis options/scaling/default=htexti
(no default)
The htexti is used as scaling whenever no other scaling is specified. This key is mainly used when
a transformation function is set using function; normally, you will not use this key directly.
Most of the time, you will not use neither the scaling nor the function key directly, but rather you
will use one of the following predefined styles documented in the following.
77.2.5
Scaling: Logarithmic Axes
/tikz/data visualization/axis options/logarithmic
(no value)
When this key is used with an axis, three things happen:
1. The transformation function of the axis is setup to the logarithm.
2. The strategy for automatically generating ticks and grid lines is set to the exponential strategy,
see Section 77.4.13 for details.
3. The default scaling is setup sensibly.
All told, to turn an axis into a logarithmic axis, you just need to add this option to the axis.
10,000
1,000
100
10
1
0.1
1 · 10−2
1 · 10−3
1 · 10−4
1 · 10−2
\tikz \datavisualization [scientific axes,
x axis={logarithmic},
y axis={logarithmic},
visualize as line]
data [format=function] {
var x : interval [0.01:100];
func y = \value x * \value x;
};
0.1
1
10
100
Note that this will work with any axis, including, say, the degrees on a polar axis:
\tikz \datavisualization
[new polar axes,
angle axis={logarithmic, scaling=1 at 0 and 90 at 90},
radius axis={scaling=0 at 0cm and 100 at 3cm},
visualize as scatter]
data [format=named] {
angle={1,10,...,90}, radius={1,10,...,100}
};
\tikz \datavisualization
[new polar axes,
angle axis={degrees},
radius axis={logarithmic, scaling=1 at 0cm and 100 at 3cm},
visualize as scatter]
data [format=named] {
angle={1,10,...,90}, radius={1,10,...,100}
};
77.2.6
Scaling: Setting the Length or Unit Length
/tikz/data visualization/axis options/length=hdimensioni
(no default)
Sets scaling to min at 0cm and max at hdimensioni. The effect is that the range of all values of the
axis’s attribute will be mapped to an interval of exact length hdimensioni.
782
30
25
20
15
10
10
12.5
15
17.5
20
30
\tikz \datavisualization [scientific axes,
x axis={length=3cm},
y axis={length=2cm},
all axes={ticks=few},
visualize as line]
data {
x, y
10, 10
20, 20
15, 30
13, 20
};
\tikz \datavisualization [scientific axes,
x axis={length=3cm},
y axis={length=4cm},
all axes={ticks=few},
visualize as line]
data {
x, y
10, 10
20, 20
15, 30
13, 20
};
25
20
15
10
10
12.5
15
17.5
20
/tikz/data visualization/axis options/unit length=hdimensioniperhnumber iunits
(no default)
Sets scaling to 0 at 0cm and 1 at hdimensioni. In other words, this key allows you to specify how
long a single unit should be. This key is particularly useful when you wish to ensure that the same
scaling is used across multiple axes or pictures.
30
25
20
15
10
10
20
30
40
\tikz \datavisualization [scientific axes,
all axes={ticks=few, unit length=1mm},
visualize as line]
data {
x, y
10, 10
40, 20
15, 30
13, 20
};
The optional per hnumber i units allows you to apply more drastic scaling. Suppose that you want to
plot a graph where one billion corresponds to one centimeter. Then the unit length would be need to
be set to a hundredth of a nanometer – much too small for TEX to handle as a dimension. In this case,
you can write unit length=1cm per 1000000000 units:
30
25
20
15
10
1 · 1010 2 · 1010 3 · 1010 4 · 1010
\tikz \datavisualization
[scientific axes,
x axis={unit length=1mm per 1000000000 units, ticks=few},
visualize as line]
data {
x, y
10000000000, 10
40000000000, 20
15000000000, 30
13000000000, 20
};
/tikz/data visualization/axis options/power unit length=hdimensioni
(no default)
This key is used in conjunction with the logarithmic setting. It cases the scaling to be set to 1 at
0cm and 10 at hdimensioni. This causes a “power unit,” that is, one power of ten in a logarithmic
plot, to get a length of hdimensioni. Again, this key is useful for ensuring that the same scaling is used
across multiple axes or pictures.
783
1 · 1030
1 · 1024
1 · 1018
1 · 1012
1 · 106
1
1 · 10−6
0
77.2.7
1
2
3
4
5
6
\tikz \datavisualization
[scientific axes,
y axis={logarithmic, power unit length=1mm, grid},
visualize as line]
data {
x, y
0, 0.0000000001
1, 1
2, 100000
3, 100000000000
4, 10000000000000000000000000000000
5, 500000000
6, 5000000000000000000
};
Axis Label
An axis can have a label, which is a textual representation of the attribute according to which the axis varies
the position of the page. You can set the attribute using the following key:
/tikz/data visualization/axis options/label={[hoptionsi]htexti}
mode)
(default axis’s label in math
This key sets the label of an axis to htexti. This text will typically be placed inside a node and the
hoptionsi can be used to further configure the way this node is rendered. The hoptionsi will be executed
with the path prefix /tikz/data visualization/, so you need to say node style to configure the
styling of a node, see Section 77.4.7.
25
\tikz \datavisualization [
scientific axes,
x axis = {label, length=2.5cm},
y axis = {label={[node style={fill=blue!20}]{$x^2$}}},
visualize as smooth line]
data [format=function] {
var x : interval [-3:5];
func y = \value x * \value x;
};
20
x2
15
10
5
0
−2
0
2
4
x
Note that using the label key does not actually cause a node to be created, because it is somewhat
unclear where the label should be placed. Instead, the visualize label key is used (typically internally by
an axis system) to show the label at some sensible position. This key is documented in Section 77.5.5.
77.2.8
Reference: Axis Types
As explained earlier, when you use new axis base to create a new axis, a powerful scaling and attribute
mapping mechanism is installed, but no mapping of values to positions on the page is performed. For this,
a transformation object must be installed. The following keys take care of this for you. Note, however, that
even these keys do not cause a visual representation of the axis to be added to the visualization – this is the
job of an axis system, see Section 77.3.
/tikz/data visualization/new Cartesian axis=hnamei
(no default)
This key creates a new “Cartesian” axis, named hnamei. For such an axis, the (scaled) values of the
axis’s attribute are transformed into a displacement on the page along a straight line. The following
key is used to configure in which “direction” the axis points:
/tikz/data visualization/axis options/unit vector=hcoordinatei
(1pt,0pt))
(no default, initially
Recall that an axis takes the values of an attribute and rescales them so that they fit into a
“reasonable” interval [t1 , t2 ]. Suppose that v 0 is the rescaled dimension in (TEX) points. Then when
the data point is visualized, the coordinate system will be shifted by v 0 times the hcoordinatei.
784
As an example, suppose that you have said scaling=0 and 10pt and 50 and 20pt. Then when
the underlying attribute has the value 25, it will be mapped to a v 0 of 15 (because 25 lies in the
middle of 0 and 50 and 15pt lies in the middle of 10pt and 20pt). This, in turn, causes the data
point to be displaced by 15 times the hcoordinatei.
The bottom line is that the hcoordinatei should usually denote a point that is at distance 1pt from
the origin and that points into the direction of the axis.
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\datavisualization
[new Cartesian axis=x axis, x axis={attribute=x},
new Cartesian axis=y axis, y axis={attribute=y},
x axis={unit vector=(0:1pt)},
y axis={unit vector=(60:1pt)},
visualize as scatter]
data {
x, y
0, 0
1, 0
2, 0
1, 1
2, 1
1, 1.5
2, 1.5
};
\end{tikzpicture}
77.3
Axis Systems
An axis system is, as the name suggests, a whole family of axes that act in concert. For example, in the
“standard” axis system there is a horizontal axis called the x-axis that monitors the x attribute (by default,
you can change this easily) and a vertical axis called the y-axis. Furthermore, a certain number of ticks are
added and labels are placed at sensible positions.
77.3.1
Usage
Using an axis system is usually pretty easy: You just specify a key like scientific axes and the necessary
axes get initialized with sensible default values. You can then start to modify these default values, if
necessary.
First, you can (and should) set the attributes to which the difference axes refer. For instance, if the time
attribute is plotted along the x-axis, you would write
x axis = {attribute = time}
Second, you may wish to modify the lengths of the axes. For this, you can use keys like length or further
keys as described in the references later on.
Third, you may often wish to modify how many ticks and grid lines are shown. By default, no grid lines
are shown, but you can say the following in order to cause grid lines to be shown:
all axes={grid}
Naturally, instead of all axes you can also specify a single axis, causing only grid lines to be shown for
this axis. In order to change the number of ticks that are shown, you can say
all axes={ticks=few}
or also many instead of few or even none. Far more fine-grained control over the tick placement and
rendering is possible, see Section 77.4 for details.
Fourth, consider adding units (like “cm” for centimeters or “m/s2 ” for acceleration) to your ticks:
x axis={ticks={tick unit=cm}}, y axis={ticks={tick unit=m/s^2}}
Finally, consider adding labels to your axes. For this, use the label option:
x axes={time $t$ (ms)}, y axis={distance $d$ (mm)}
Here is an example that employs most of the above features:
785
speed of disc
1.25 · 10−2 m/s
1 · 10−2 m/s
7.5 · 10−3 m/s
5 · 10−3 m/s
2.5 · 10−3 m/s
0 m/s
0 ms 1 ms 2 ms 3 ms 4 ms 5 ms 6 ms
elapsed time
77.3.2
\tikz \datavisualization [
scientific axes=clean,
x axis={attribute=time, ticks={tick unit=ms},
label={elapsed time}},
y axis={attribute=v, ticks={tick unit=m/s},
label={speed of disc}},
all axes=grid,
visualize as line]
data {
time, v
0, 0
1, 0.001
2, 0.002
3, 0.004
4, 0.0035
5, 0.0085
6, 0.0135
};
Reference: Scientific Axis Systems
(no default)
/tikz/data visualization/scientific axes=hoptionsi
This key installs a two-dimensional coordinate system based on the attributes /data point/x and /data
point/y.
10
\begin{tikzpicture}
\datavisualization [scientific axes,
visualize as smooth line]
data [format=function] {
var x : interval [0:100];
func y = sqrt(\value x);
};
\end{tikzpicture}
8
6
4
2
0
0
20
40
60
80
100
This axis system is usually a good choice to depict “arbitrary two dimensional data.” Because the axes
are automatically scaled, you do not need to worry about how large or small the values will be. The name
scientific axes is intended to indicate that this axis system is often used in scientific publications.
You can use the hoptionsi to fine tune the axis system. The hoptionsi will be executed with the following
path prefix:
/tikz/data visualization/scientific axes
All keys with this prefix can thus be passed as hoptionsi.
This axis system will always distort the relative magnitudes of the units on the two axis. If you wish
the units on both axes to be equal, consider directly specifying the unit length “by hand”:
10
7.5
5
2.5
0
0
25
50
75
100
\begin{tikzpicture}
\datavisualization [visualize as smooth line,
scientific axes,
all axes={unit length=1cm per 10 units, ticks={few}}]
data [format=function] {
var x : interval [0:100];
func y = sqrt(\value x);
};
\end{tikzpicture}
The scientific axes have the following properties:
• The x-values are surveyed and the x-axis is then scaled and shifted so that it has the length specified
by the following key.
786
/tikz/data visualization/scientific axes/width=hdimensioni
(no default, initially 5cm)
The minimum value is at the left end of the axis and at the canvas origin. The maximum value is
at the right end of the axis.
• The y-values are surveyed and the y-axis is then scaled so that is has the length specified by the
following key.
/tikz/data visualization/scientific axes/height=hdimensioni
(no default)
By default, the height is the golden ratio times the width.
The minimum value is at the bottom of the axis and at the canvas origin. The maximum value is
at the top of the axis.
• Lines (forming a frame) are depicted at the minimum and maximum values of the axes in 50%
black.
The following keys are executed by default as options: outer ticks and standard labels.
You can use the following style to overrule the defaults:
/tikz/data visualization/every scientific axes
(style, no value)
The keys described in the following can be used to fine-tune the way the scientific axis system is rendered.
/tikz/data visualization/scientific axes/outer ticks
(no value)
This causes the ticks to be drawn “ on the outside” of the frame so that they interfere as little as possible
with the data. It is the default.
\begin{tikzpicture}
\datavisualization [scientific axes=outer ticks,
visualize as smooth line]
data [format=function] {
var x : interval [-12:12];
func y = \value x*\value x*\value x;
};
\end{tikzpicture}
1,500
1,000
500
0
−500
−1,000
−1,500
−10
−5
0
5
10
/tikz/data visualization/scientific axes/inner ticks
(no value)
This axis system works like scientific axes, only the ticks are on the “inside” of the frame.
\begin{tikzpicture}
\datavisualization [scientific axes=inner ticks,
visualize as smooth line]
data [format=function] {
var x : interval [-12:12];
func y = \value x*\value x*\value x;
};
\end{tikzpicture}
1,500
1,000
500
0
−500
−1,000
−1,500
−10
−5
0
5
10
This axis system is also common in publications, but the ticks tend to interfere with marks if they are
near to the border as can be seen in the following example:
787
1
0.8
0.6
0.4
0.2
0
0
0.5
1
1.5
2
\begin{tikzpicture}
\datavisualization [scientific axes={inner ticks, width=3.2cm},
style sheet=cross marks,
visualize as scatter/.list={a,b}]
data [set=a] {
x, y
0, 0
1, 1
0.5, 0.5
2, 1
}
data [set=b] {
x, y
0.05, 0
1.5, 1
0.5, 0.75
2, 0.5
};
\end{tikzpicture}
/tikz/data visualization/scientific axes/clean
(no value)
The axes and the ticks are completely removed from the actual data, making this axis system especially
useful for scatter plots, but also for most other scientific plots.
\tikz \datavisualization [
scientific axes=clean,
visualize as smooth line]
data [format=function] {
var x : interval [-12:12];
func y = \value x*\value x*\value x;
};
1,500
1,000
500
0
−500
−1,000
−1,500
−10
−5
0
5
10
The distance of the axes from the actual plot is given by the padding of the axes.
For all scientific axis systems, different label placement strategies can be specified. They are discussed
in the following.
/tikz/data visualization/scientific axes/standard labels
(no value)
As the name suggests, this is the standard placement strategy. The label of the x-axis is placed below
the center of the x-axis, the label of the y-axis is rotated by 90◦ and placed left of the center of the
y-axis.
\tikz \datavisualization
[scientific axes={clean, standard labels},
visualize as smooth line,
x axis={label=degree $d$,
ticks={tick unit={}^\circ}},
y axis={label=$\sin d$}]
data [format=function] {
var x : interval [-10:10] samples 10;
func y = sin(\value x);
};
0.15
sin d
0.1
5 · 10−2
0
−5 · 10−2
−0.1
−0.15
−10 ◦
−5 ◦
0◦
5◦
10 ◦
degree d
/tikz/data visualization/scientific axes/upright labels
Works like scientific axes standard labels, only the label of the y-axis is not rotated.
788
(no value)
1.0000
\tikz \datavisualization [
scientific axes={clean, upright labels},
visualize as smooth line,
x axis={label=degree $d$,
ticks={tick unit={}^\circ}},
y axis={label=$\cos d$, include value=1,
ticks={style={
/pgf/number format/precision=4,
/pgf/number format/fixed zerofill}}}]
data [format=function] {
var x : interval [-10:10] samples 10;
func y = cos(\value x);
};
0.9975
0.9950
cos d 0.9925
0.9900
0.9875
0.9850
−10 ◦
−5 ◦
0◦
5◦
10 ◦
degree d
/tikz/data visualization/scientific axes/end labels
(no value)
Places the labels at the end of the x- and the y-axis, similar to the axis labels of a school book axis
system.
\tikz \datavisualization [
scientific axes={clean, end labels},
visualize as smooth line,
x axis={label=degree $d$,
ticks={tick unit={}^\circ}},
y axis={label=$\tan d$}]
data [format=function] {
var x : interval [-80:80];
func y = tan(\value x);
};
tan d
4
2
0
−2
−4
−75 ◦ −50 ◦ −25 ◦ 0 ◦
77.3.3
25 ◦
50 ◦
75 ◦
degree d
Reference: School Book Axis Systems
/tikz/data visualization/school book axes=hoptionsi
(no default)
This axis system is intended to “look like” the coordinate systems often used in school books: The axes
are drawn in such a way that they intersect to origin. Furthermore, no automatic scaling is done to
ensure that the lengths of units are the same in all directions.
This axis system must be used with care – it is nearly always necessary to specify the desired unit length
by hand using the option unit length. If the magnitudes of the units on the two axes differ, different
unit lengths typically need to be specified for the different axes.
Finally, if the data is “far removed” from the origin, this axis system will also “look bad.”
\begin{tikzpicture}
\datavisualization [school book axes, visualize as smooth line]
data [format=function] {
var x : interval [-1.3:1.3];
func y = \value x*\value x*\value x;
};
\end{tikzpicture}
2
1
−1
0
1
−1
−2
The stepping of the ticks is one unit by default. Using keys like ticks=some may help to give better
steppings.
The hoptionsi are executed with the key itself as path prefix. Thus, the following subkeys are permissible
options:
/tikz/data visualization/school book axes/unit=hvaluei
789
(no default)
Sets the scaling so that 1 cm corresponds to hvaluei units. At the same time, the stepping of the
ticks will also be set to hvaluei.
f (x)
40
30
20
10
−20
x
0
−10
10
20
\begin{tikzpicture}
\datavisualization [school book axes={unit=10},
visualize as smooth line,
clean ticks,
x axis={label=$x$},
y axis={label=$f(x)$}]
data [format=function] {
var x : interval [-20:20];
func y = \value x*\value x/10;
};
\end{tikzpicture}
/tikz/data visualization/school book axes/standard labels
(no value)
This key makes the label of the x-axis appear at the right end of this axis and it makes the label
of the y-axis appear at the top of the y-axis.
Currently, this is the only supported placement strategy for the school book axis system.
f (x)
2
1
−1
77.3.4
0
x
1
\begin{tikzpicture}
\datavisualization [school book axes={standard labels},
visualize as smooth line,
clean ticks,
x axis={label=$x$},
y axis={label=$f(x)$}]
data [format=function] {
var x : interval [-1:1];
func y = \value x*\value x + 1;
};
\end{tikzpicture}
Advanced Reference: Underlying Cartesian Axis Systems
The axis systems described in the following are typically not used directly by the user. The systems setup
directions for several axes in some sensible way, but they do not actually draw anything on these axes. For
instance, the xy Cartesian creates two axes called x axis and y axis and makes the x-axis point right and
the y-axis point up. In contrast, an axis system like scientific axes uses the axis system xy Cartesian
internally and then proceeds to setup a lot of keys so that the axis lines are drawn, ticks and grid lines are
drawn, and labels are placed at the correct positions.
(no value)
/tikz/data visualization/xy Cartesian
This axis system creates two axes called x axis and y axis that point right and up, respectively. By
default, one unit is mapped to one cm.
790
\begin{tikzpicture}
\datavisualization [xy Cartesian, visualize as smooth line]
data [format=function] {
var x : interval [-1.25:1.25];
func y = \value x*\value x*\value x;
};
\end{tikzpicture}
/tikz/data visualization/xy axes=hoptionsi
(no default)
This key applies the hoptionsi both to the x axis and the y axis.
/tikz/data visualization/xyz Cartesian cabinet
(no value)
This axis system works like xy Cartesian, only it additionally creates an axis called z axis that
points left and down. For this axis, one unit corresponds to 12 sin 45◦ cm. This is also known as a cabinet
projection.
/tikz/data visualization/xyz axes=hoptionsi
(no default)
This key applies the hoptionsi both to the x axis and the y axis.
(no value)
/tikz/data visualization/uv Cartesian
This axis system works like xy Cartesian, but it introduces two axes called u axis and v axis rather
than the x axis and the y axis. The idea is that in addition to a “major” xy-coordinate system this
is also a “smaller” or “minor” coordinate system in use for depicting, say, small vectors with respect to
this second coordinate system.
/tikz/data visualization/uv axes=hoptionsi
(no default)
Applies the hoptionsi to both the u axis and the y axis.
/tikz/data visualization/uvw Cartesian cabinet
(no value)
Like xyz Cartesian cabinet, but for the uvw-system.
/tikz/data visualization/uvw axes=hoptionsi
(no default)
Like xyz axes.
77.4
77.4.1
Ticks and Grids
Concepts
A tick is a small visual indication on an axis of the value of the axis’s attribute at the position where the
tick is shown. A tick may be accompanied additionally by a textual representation, but it need not. A grid
line is similar to a tick, but it is not an indication on the axis, but rather a whole line that indicates all
positions where the attribute has a certain value. Unlike ticks, grid lines (currently) are not accompanied
by a textual representation.
Just as for axes, the data visualization system decouples the specification of which ticks are present in
principle from where they are visualized. In the following, I describe how you specify which ticks and grid
lines you would like to be drawn and how they should look like (their styling). The axis system of your
choice will then visualize the ticks at a sensible position for the chosen system. For details on how to change
where whole axis is shown along with its ticks, see Section 77.5.4.
Specifying which ticks you are interested in is done as follows: First, you use ticks key (or, for specifying
which grid lines should be present, the grid key). This key takes several possible options, described in detail
in the following, which have different effects:
1. Keys like step=10 or minor steps between steps cause a “semi-automatic” computation of possible
steps. Here, you explicitly specify the stepping of steps, but the first stepping and their number are
computed automatically according to the range of possible values for the attribute.
791
2. Keys like few, some, or many can be passed to ticks in order to have Tik Z compute good tick positions
automatically. This is usually what you want to happen, which is why most axis system will implicitly
say ticks={some}.
3. Keys like at or also at provide “absolute control” over which ticks or grid lines are shown. For these
keys, you can not only specify at what value a tick should be shown, but also its styling and also
whether it is a major, minor, or subminor tick or grid line.
In the following, the main keys ticks and grids are documented first. Then the different kinds of ways
of specifying where ticks or grid lines should be shown are explained.
77.4.2
The Main Options: Tick and Grid
(default some)
/tikz/data visualization/axis options/ticks=hoptionsi
This key can be passed to an axis in order to configure which ticks are present for the axis. The possible
hoptionsi include, for instance, keys like step, which is used to specify a stepping for the ticks, but also
keys like major or minor for specifying the positions of major and minor ticks in detail. The list of
possible options is described in the rest of this section.
Note that the ticks option will only configure which ticks should be shown in principle. The actual
rendering is done only when the visualize ticks key is used, documented in Section 77.5.4, which is
typically done only internally by an axis system.
The hoptionsi will be executed with the path prefix /tikz/data visualization/. When the ticks
key is used multiple times for an axis, the hoptionsi accumulate.
\tikz \datavisualization [
scientific axes, visualize as line,
x axis={ticks={step=24, minor steps between steps=3},
label=hours}]
data {
x, y
0, 0
10, 0
20, 0.5
30, 0.75
40, 0.7
50, 0.6
60, 0.5
70, 0.45
80, 0.47
};
0.6
0.4
0.2
0
0
24
48
72
hours
(default at default ticks)
/tikz/data visualization/axis options/grid=hoptionsi
This key is similar to ticks, only it is used to configure where grid lines should be shown rather than
ticks. In particular, the options that can be passed to the ticks key can also be passed to the grid
key. Just like ticks, the hoptionsi only specify which grid lines should be drawn in principle; it is the
job of the visualize grid key to actually cause any grid lines to be shown.
If you do not specify any hoptionsi, the default text at default ticks is used. This option causes grid
lines to be drawn at all positions where ticks are shown by default. Since this usually exactly what you
would like to happen, most of the time you just need to all axes=grid to cause a grid to be shown.
(no default)
/tikz/data visualization/axis options/ticks and grid=hoptionsi
This key passes the hoptionsi to both the ticks key and also to the grid key. This is useful when you
want to specify some special points explicitly where you wish a tick to be shown and also a grid line.
1
0.5
0
−0.5
−1
−1
0
1
π
2
2
3
4
792
5
6
7
8
9
\tikz \datavisualization
[scientific axes,
visualize as smooth line,
all axes= {grid, unit length=1.25cm},
y axis={ ticks=few },
x axis={ ticks=many, ticks and grid={ major also at={(pi/2) as $\frac{\pi}{2}$}}}]
data [format=function] {
var x : interval [-pi/2:3*pi] samples 50;
func y = sin(\value x r);
};
77.4.3
Semi-Automatic Computation of Tick and Grid Line Positions
Consider the following problem: The data visualization engine determines that in a plot the x-values vary
between 17.4 and 34.5. In this case, we certainly do not want, say, ten ticks at exactly ten evenly spaced
positions starting with 17.4 and ending with 34.5, because this would yield ticks at positions like 32.6. Ticks
should be placed at “nice” positions like 20, 25, and 30.
Determining which positions are “nice” is somewhat difficult. In the above example, the positions 20, 25,
and 30 are certainly nice, but only three ticks may be a bit few of them. Better might be the tick positions
17.5, 20, 22.5, through to 32.5. However, users might prefer even numbers over fractions like 2.5 as the
stepping.
A tick placement strategy is a method of automatically deciding which positions are good for placing
ticks. The data visualization engine comes with a number of predefined strategies, but you can also define
new ones yourself. When the data visualization is requested to automatically determine “good” positions
for the placement of ticks on an axis, it uses one of several possible basic strategies. These strategies differ
dramatically in which tick positions they will choose: For a range of values between 5 and 1000, a linear
steps strategy might place ticks at positions 100, 200, through to 1000, while an exponential steps
strategy would prefer the tick positions 10, 100 and 1000. The exact number and values of the tick positions
chosen by either strategy can be fine-tuned using additional options like step or about.
Here is an example of the different stepping chosen when one varies the tick placement strategy:
100
100
75
50
25
10
1
2
4
6
8
10
2.5
5
7.5
10
\begin{tikzpicture}
\datavisualization [scientific axes, visualize as smooth line]
data [format=function] {
var x : interval [1:11];
func y = \value x*\value x;
};
\end{tikzpicture}
\qquad
\begin{tikzpicture}
\datavisualization [scientific axes, visualize as smooth line,
y axis={exponential steps},
x axis={ticks={quarter about strategy}},
]
data [format=function] {
var x : interval [1:11];
func y = \value x*\value x;
};
\end{tikzpicture}
Two strategies are always available: linear steps, which yields (semi)automatic ticks are evenly spaced
positions, and exponential steps, which yields (semi)automatic steps at positions at exponentially increasing positions – which is exactly what is needed for logarithmic plots. These strategies are details in
Section 77.4.13.
793
The following options are used to configure tick placement strategies like linear steps. Unlike the basic
choice of a placement strategy, which is an axis option, the following should be passed to the option ticks
or grid only. So, you would write things like x axis={ticks={step=2}}, but x axis={linear steps}.
(no default, initially 1)
/tikz/data visualization/step=hvaluei
The value of this key is used to determine the spacing of the major ticks. The key is used by the linear
steps and exponential steps strategies, see the explanations in Section 77.4.13 for details. Basically,
all ticks are placed at all multiples of hvaluei that lie in the attribute range interval.
\tikz \datavisualization [
school book axes, visualize as smooth line,
y axis={ticks={step=1.25}},
]
data [format=function] {
var x : interval [0:3];
func y = \value x*\value x/2;
};
3.75
2.5
1.25
0
1
2
3
/tikz/data visualization/minor steps between steps=hnumber i
(default 9)
Specifies that between any two major steps (whose positions are specified by the step key), there should
be hnumber i many minor steps. Note that the default of 9 is exactly the right number so that each
interval between two minor steps is exactly a tenth of the size of a major step. See also Section 77.4.13
for further details.
2
1
−1
0
1
\begin{tikzpicture}
\datavisualization [school book axes, visualize as smooth line,
x axis={ticks={minor steps between steps=3}},
y axis={ticks={minor steps between steps}},
]
data [format=function] {
var x : interval [-1.5:1.5];
func y = \value x*\value x;
};
\end{tikzpicture}
(no default, initially 0)
/tikz/data visualization/phase=hvaluei
See Section 77.4.13 for details on how the phase of steps influences the tick placement.
77.4.4
Automatic Computation of Tick and Grid Line Positions
The step option gives you “total control” over the stepping of ticks on an axis, but you often do not know
the correct stepping in advance. In this case, you may prefer to have a good value for step being computed
for you automatically.
Like the step key, these options are passed to the ticks option. So, for instance, you would write x
axis={ticks={about=4}} to request about four ticks to be placed on the x-axis.
/tikz/data visualization/about=hnumber i
(no default)
This key asks the data visualization to place about hnumber i many ticks on an axis. It is not guaranteed
that exactly hnumber i many ticks will be used, rather the actual number will be the closest number of
ticks to hnumber i so that their stepping is still “good”. For instance, when you say about=10, it may
happen that exactly 10, but perhaps even 13 ticks are actually selected, provided that these numbers
of ticks lead to good stepping values like 5 or 2.5 rather than numbers like 3.4 or 7. The method that
is used to determine which steppings a deemed to be “good” depends on the current tick placement
strategy.
794
Linear steps. Let us start with linear steps: First, the difference between the maximum value vmax
and the minimum value vmin on the axis is computed; let us call it r for “range.” Then, r is divided
by hnumber i, yielding a target stepping s. If s is a number like 1 or 5 or 10, then this number could
be used directly as the new value of step. However, s will typically something strange like 0.02345 or
345223.76, so s must be replaced by a better value like 0.02 in the first case and perhaps 250000 in the
second case.
In order to determine which number is to be used, s is rewritten in the form m · 10k with 1 ≤ m < 10
and k ∈ Z. For instance, 0.02345 would be rewritten as 2.345 · 10−2 and 345223.76 as 3.4522376 · 105 .
The next step is to replace the still not-so-good number m like 2.345 or 3.452237 by a “good” value m0 .
For this, the current value of the about strategy is used:
(no default)
/tikz/data visualization/about strategy=hlisti
The hlisti is a comma-separated sequence of pairs hthreshold i/hvaluei like for instance 1.5/1.0 or
2.3/2.0. When a good value m0 is sought for a given m, we iterate over the list and find the first
pair hthreshold i/hvaluei where hthreshold i exceeds m. Then m0 is set to hvaluei. For instance, if
hlisti is 1.5/1.0,2.3/2.0,4/2.5,7/5,11/10, which is the default, then for m = 3.141 we would
get m0 = 2.5 since 4 > 3.141, but 2.3 ≤ 3.141. For m = 6.3 we would get m0 = 5.
Once m0 has been determined, the stepping is set to s0 = m0 · 10k .
The net effect of all this is that for the default strategy the only valid stepping are the values 1, 2, 2.5
and 5 and every value obtainable by multiplying one of these values by a power of ten. The following
example shows the effects of, first, setting about=5 (corresponding to the some option) and then having
axes where the minimum value is always 0 and where the maximum value ranges from 10 to 100 and,
second, setting about to the values from 3 (corresponding to the few option) and to 10 (corresponding
to the many option) while having the minimum at 0 and the maximum at 100:
10
20
30
40
25
8
15
30
20
6
10
5
about= 5
0
5
0
5
5
10
0
0
0
5
60
40
20
10
5
80
60
30
20
100
100
90
80
70
60
50
40
30
20
10
0
80
40
10
100
80
50
40
20
10
0
40
60
30
10
0
70
50
20
5
2
60
30
15
4
50
50
40
40
20
20
20
0
0
0
5
5
75
60
5
25
0
5
3
10
Exponential steps. For exponential steps the strategy for determining a good stepping value is
similar to linear steps, but with the following differences:
• Naturally, since the stepping value refers to the exponent, the whole computation of a good stepping
value needs to be done “in the exponent.” Mathematically spoken, instead of considering the
difference r = vmax − vmin , we consider the difference r = log vmax − log vmin . With this difference,
we still compute s = r/hnumber i and let s = m · 10k with 1 ≤ m < 10.
• It makes no longer sense to use values like 2.5 for m0 since this would yield a fractional exponent. Indeed, the only sensible values for m0 seem to be 1, 3, 6, and 10. Because of this, the
about strategy is ignored and one of these values or a multiple of one of them by a power of ten
is used.
The following example shows the chosen steppings for a maximum varying from 101 to 105 and from
1010 to 1050 as well as for 10100 for about=3:
10
100
1,000
10,000
1,000
100
1,000
1 · 1018
1 · 106
1 · 1012
1,000
1 · 106
100
10
10
1
10,000
1 · 109
1 · 1030
1 · 1024
1 · 1018
100
10
1
1 · 105
1
1
10
1
1
795
1
1 · 1012
1 · 106
1
1 · 1040
1·
1030
1 · 1020
1·
1010
1
1 · 1050
1 · 1040
1 · 1030
1 · 1020
1 · 1010
1
1 · 1090
1 · 1060
1 · 1030
1
Alternative strategies.
In addition to the standard about strategy, there are some additional strategies that you might wish
to use instead:
(no value)
/tikz/data visualization/standard about strategy
Permissible values for m0 are: 1, 2, 2.5, and 5. This strategy is the default strategy.
(no value)
/tikz/data visualization/euro about strategy
Permissible values for m0 are: 1, 2, and 5. These are the same values as for the Euro coins, hence
the name.
10
8
20
30
40
30
20
10
20
10
10
0
0
5
0
5
50
60
60
40
20
20
10
0
5
100
100
90
80
70
60
50
40
30
20
10
0
80
60
30
0
5
100
80
40
10
0
5
80
50
20
10
5
about= 5
70
30
20
5
60
40
30
15
4
0
50
25
15
6
2
40
0
5
60
50
40
40
20
20
0
5
0
5
0
5
3
10
(no value)
/tikz/data visualization/half about strategy
0
Permissible values for m : 1 and 5. Use this strategy if only powers of 10 or halves thereof seem
logical.
10
20
30
40
50
25
15
40
30
20
5
10
20
10
10
5
0
0
about= 5
0
5
0
5
50
60
40
10
0
0
5
30
20
10
5
80
70
60
50
40
30
20
10
0
50
30
20
5
70
40
30
15
60
20
10
0
5
5
90
80
70
60
50
40
30
20
10
0
5
100
100
50
50
0
5
100
90
80
70
60
50
40
30
20
10
0
0
5
3
10
(no value)
/tikz/data visualization/decimal about strategy
0
The only permissible value for m is 1. This is an even more radical version of the previous strategy.
10
9
8
7
6
5
4
3
2
1
0
about= 5
20
30
40
50
40
30
20
20
20
10
0
5
0
5
50
60
40
5
30
20
10
10
0
0
5
80
70
60
50
40
30
20
10
0
50
30
10
0
70
40
30
10
60
20
10
0
5
5
/tikz/data visualization/quarter about strategy
0
Permissible values for m are: 1, 2.5, and 5.
796
100
90
80
70
60
50
40
30
20
10
0
90
80
70
60
50
40
30
20
10
0
5
5
100
100
90
80
70
60
50
40
30
20
10
0
0
5
3
10
(no value)
10
20
30
40
25
7.5
15
30
20
5
10
15
0
5
0
5
40
20
10
0
5
30
20
10
10
0
5
80
70
60
50
40
30
20
10
0
50
40
20
10
0
40
60
30
5
0
70
50
20
5
about= 5
60
30
10
2.5
50
0
5
5
90
80
70
60
50
40
30
20
10
0
5
100
100
75
75
50
50
25
25
0
5
100
90
80
70
60
50
40
30
20
10
0
0
5
3
10
(no value)
/tikz/data visualization/int about strategy
Permissible values for m0 are: 1, 2, 3, 4, and 5.
10
8
6
20
30
16
25
40
30
20
12
8
2
4
0
0
about= 5
70
40
50
60
10
10
5
0
0
5
10
0
5
40
20
10
0
5
80
60
20
0
5
0
5
100
90
80
70
60
50
40
30
20
10
0
90
60
30
20
100
80
40
30
20
80
50
40
20
10
5
60
30
15
4
50
60
40
40
20
20
30
0
5
60
0
5
0
5
3
10
/tikz/data visualization/many
This is an abbreviation for about=10.
(no value)
/tikz/data visualization/some
(no value)
This is an abbreviation for about=5.
(no value)
/tikz/data visualization/few
This is an abbreviation for about=3.
(no value)
/tikz/data visualization/none
Switches off the automatic step computation. Unless you use step= explicitly to set a stepping, no ticks
will be (automatically) added.
77.4.5
Manual Specification of Tick and Grid Line Positions
The automatic computation of ticks and grid lines will usually do a good job, but not always. For instance,
you might wish to have ticks exactly at, say, prime numbers or at Fibonacci numbers or you might wish
to have an additional tick at π. In these cases you need more direct control over the specification of tick
positions.
First, it is important to understand that the data visualization system differentiates between three kinds
of ticks and grid lines: major, minor, and subminor. The major ticks are the most prominent ticks where,
typically, a textual representation of the tick is shown; and the major grid lines are the thickest. The
minor ticks are smaller, more numerous, and lie between major ticks. They are used, for instance, to
indicate positions in the middle between major ticks or at all integer positions between major ticks. Finally,
subminor ticks are even smaller than minor ticks and they lie between minor ticks.
Four keys are used to configure the different kinds:
(no default)
/tikz/data visualization/major=hoptionsi
The key can be passed as an option to the ticks key and also to the grid key, which in turn is passed
as an option to an axis. The hoptionsi passed to major specify at which positions major ticks/grid lines
should be shown (using the at option and also at option) and also any special styling. The different
possible options are described later in this section.
797
\tikz \datavisualization
[ school book axes, visualize as smooth line,
x axis={ticks={major={at={1, 1.5, 2}}}}]
data [format=function] {
var x : interval [-1.25:2];
func y = \value x * \value x / 2;
};
2
1
0
1 1.5 2
(no default)
/tikz/data visualization/minor=hoptionsi
Like major, only for minor ticks/grid lines.
\tikz \datavisualization
[ school book axes, visualize as smooth line,
x axis={grid={minor={at={1, 1.5, 2}}}}]
data [format=function] {
var x : interval [-1.25:2];
func y = \value x * \value x / 2;
};
2
1
−1
0
1
2
(no default)
/tikz/data visualization/subminor=hoptionsi
Like major, only for subminor ticks/grid lines.
(no default)
/tikz/data visualization/common=hoptionsi
This key allows you to specify hoptionsi that apply to major, minor and subminor alike. It does not
make sense to use common to specify positions (since you typically do not want both a major and a
minor tick at the same position), but it can be useful to configure, say, the size of all kinds of ticks:
\tikz \datavisualization
[ school book axes, visualize as smooth line,
x axis={ticks={minor steps between steps, common={low=0}}} ]
data [format=function] {
var x : interval [-1.25:2];
func y = \value x * \value x / 2;
};
2
1
−1
0
1
2
The following keys can now be passed to the major, minor, and subminor keys to specify where ticks or
grid lines should be shown:
(no default)
/tikz/data visualization/at=hlisti
Basically, the hlisti must be a list of values that is processed with the \foreach macro (thus, it can
contain ellipses to specify ranges of value). Empty values are skipped.
The effect of passing at to a major, minor, or subminor key is that ticks or grid lines on the axis will
be placed exactly at the values in hlisti. Here is an example:
\tikz \datavisualization
[ school book axes, visualize as smooth line,
x axis={ticks={major={at={-1,0.5,(pi/2)}}}}]
data [format=function] {
var x : interval [-1.25:2];
func y = \value x * \value x / 2;
};
2
1
−1
0
0.5
1.57
When this option is used, any previously specified tick positions are overwritten by the values in hlisti.
Automatically computed ticks are also overwritten. Thus, this option gives you complete control over
where ticks should be placed.
Normally, the individual values inside the hlisti are just numbers that are specified in the same way as
an attribute value. However, such a value may also contain the keyword as, which allows you so specify
the styling of the tick in detail. Section 77.4.6 details how this works.
798
It is often a bit cumbersome that one has to write things like
some axis = {ticks = {major = {at = {...}}}}
A slight simplification is given by the following keys, which can be passed directly to ticks and grid:
(no default)
/tikz/data visualization/major at=hlisti
A shorthand for major={at={hlisti}}.
(no default)
/tikz/data visualization/minor at=hlisti
A shorthand for major={at={hlisti}}.
/tikz/data visualization/subminor at=hlisti
(no default)
A shorthand for major={at={hlisti}}.
(no default)
/tikz/data visualization/also at=hlisti
This key is similar to at, but it causes ticks or grid lines to be placed at the positions in the hlisti in
addition to the ticks that have already been specified either directly using at or indirectly using keys
like step or some. The effect of multiple calls of this key accumulate. However, when at is used after
an also at key, the at key completely resets the positions where ticks or grid lines are shown.
\tikz \datavisualization
[ school book axes, visualize as smooth line,
x axis={grid, ticks and grid={major={also at={0.5}}}}]
data [format=function] {
var x : interval [-1.25:2];
func y = \value x * \value x / 2;
};
2
1
−1
0
0.5 1
2
As for at, there are some shorthands available:
/tikz/data visualization/major also at=hlisti
(no default)
A shorthand for major={also at={hlisti}}.
/tikz/data visualization/minor also at=hlisti
(no default)
A shorthand for major={also at={hlisti}}.
/tikz/data visualization/subminor also at=hlisti
(no default)
A shorthand for major={also at={hlisti}}.
77.4.6
Styling Ticks and Grid Lines: Introduction
When a tick, a tick label, or a grid line is visualized on the page, a whole regiment of styles influences
the appearance. The reason for this large number of interdependent styles is the fact that we often wish
to influence only a very certain part of how a tick is rendered while leaving the other aspects untouched:
Sometimes we need to modify just the font of the tick label; sometimes we wish to change the length of the
tick label and the tick label position at the same time; sometimes we wish to change the color of grid line,
tick, and tick label; and sometimes we wish to generally change the thickness of all ticks.
Let us go over the different kinds of things that can be styled (grid lines, ticks, and tick labels) one by
one and let us have a look at which styles are involved. We will start with the grid lines, since they turn
out to be the most simple, but first let us have a look at the general style and styling mechanism that is
used in many placed in the following:
77.4.7
Styling Ticks and Grid Lines: The Style and Node Style Keys
All keys of the data visualization system have the path prefix /tikz/data visualization. This is not only
true for the main keys like scientific axes or visualize as line, but also for keys that govern how ticks
are visualized. In particular, a style like every major grid has the path prefix /tikz/data visualization
and all keys stored in this style are also executed with this path prefix.
Normally, this does not cause any trouble since most of the keys and even styles used in a data visualization
are intended to configure what is shown in the visualization. However, at some point, we may also with to
799
specify options that no longer configure the visualization in general, but specify the appearance of a line or
a node on the Tik Z layer.
Two keys are used to “communicate” with the Tik Z layer:
/tikz/data visualization/style=hTi kZ optionsi
(no default)
This key takes options whose path prefix is /tikz, not /tikz/data visualization. These options will
be appended to a current list of such options (thus, multiple calls of this key accumulate). The resulting
list of keys is not executed immediately, but it will be executed whenever the data visualization engine
calls the Tik Z layer to draw something (this placed will be indicated in the following).
100
90
80
70
60
50
40
30
\tikz \datavisualization
[scientific axes,
all axes={ticks={style=blue}, length=3cm},
y axis={grid, grid={minor steps between steps, major={style=red}}},
visualize as line]
data [format=function] {
var x : interval [5:10];
func y = \value x * \value x;
};
5
6
7
8
9
10
(no value)
/tikz/data visualization/styling
Executing this key will cause all “accumulated” Tik Z options from previous calls to the key
/tikz/data visualization/style to be executed. Thus, you use style to set Tik Z options, but
you use styling to actually apply these options. Usually, you do not call this option directly since this
application is only done deep inside the data visualization engine.
Similar to style (and styling) there also exist the node style (and node styling) key that takes
Tik Z options that apply to nodes only – in addition to the usual style.
/tikz/data visualization/node style=hTi kZ optionsi
(no default)
This key works like style, only it has an effect only on nodes that are created during a data visualization.
This includes tick labels and axis labels:
100
90
80
70
60
50
40
30
\tikz \datavisualization
[scientific axes,
all axes={ticks={node style=red}, length=3cm},
visualize as line]
data [format=function] {
var x : interval [5:10];
func y = \value x * \value x;
};
5
6
7
8
9
10
Note that in the example the ticks themselves (the little thicker lines) are not red.
(no value)
/tikz/data visualization/node styling
Executing this key will cause all “accumulated” node stylings to be executed.
77.4.8
Styling Ticks and Grid Lines: Styling Grid Lines
When a grid line is visualized, see Section 77.5.3 for details on when this happens, the following styles are
executed in the specified order.
1. grid layer.
2. every grid.
3. every major grid or every minor grid or every subminor grid, depending on the kind of grid
line.
800
4. locally specified options for the individual grid line, see Section 77.4.11.
5. styling, see Section 77.4.7.
All of these keys have the path prefix /tikz/data visualization. However, the options stored in
the first style (grid layer) and also in the last (styling) are executed with the path prefix /tikz (see
Section 77.4.7).
Let us now have a look at these keys in detail:
(style, initially on background layer)
/tikz/data visualization/grid layer
This key is used to specified the layer on which grid lines should be drawn (layers are explained in
Section 43). By default, all grid lines are placed on the background layer and thus behind the data
visualization. This is a sensible strategy since it avoids obscuring the more important data with the far
less important grid lines. However, you can change this style to “get the grid lines to the front”:
100
90
80
70
60
50
40
30
5
6
7
8
9
10
\tikz \datavisualization
[scientific axes,
all axes={
length=3cm,
grid,
grid={minor steps between steps}
},
grid layer/.style=, % none, so on top of data (bad idea)
visualize as line]
data [format=function] {
var x : interval [5:10];
func y = \value x * \value x;
};
When this style is executed, the keys stored in the style will be executed with the prefix /tikz. Normally,
you should only set this style to be empty or to on background layer.
(style, no value)
/tikz/data visualization/every grid
This style provides overall configuration options for grid lines. By default, it is set to the following:
low=min, high=max
This causes grid lines to span all possible values when they are visualized, which is usually the desired
behaviour (the low and high keys are explained in Section 77.5.4. You can append the style key to this
style to configure the overall appearance of grid lines. In the following example we cause all grid lines
to be dashed (which is not a good idea in general since it creates a distracting background pattern).
100
90
80
70
60
50
40
30
\tikz \datavisualization
[scientific axes,
all axes={length=3cm, grid},
every grid/.append style={style=densely dashed},
visualize as line]
data [format=function] {
var x : interval [5:10];
func y = \value x * \value x;
};
5
6
7
8
9
10
(style, no value)
/tikz/data visualization/every major grid
This style configures the appearance of major grid lines. It does so by calling the style key to setup
appropriate Tik Z options for visualizing major grid lines. The default definition of this style is:
style = {help lines, thin, black!25}
In the following example, we use thin major blue grid lines:
801
100
90
80
70
60
50
40
30
5
6
7
8
9
10
\tikz \datavisualization
[scientific axes,
all axes={
length=3cm,
grid,
grid={minor steps between steps}
},
every major grid/.style = {style={blue, thin}},
visualize as line]
data [format=function] {
var x : interval [5:10];
func y = \value x * \value x;
};
As can be seen, this is not exactly visually pleasing. The default settings for the grid lines should work
in most situations; you may wish to increase the blackness level, however, when you experience trouble
during printing or projecting graphics.
(style, no value)
/tikz/data visualization/every minor grid
Works like every major grid. The default is
style = {help lines, black!25}
/tikz/data visualization/every subminor grid
(style, no value)
Works like every major grid. The default is
style = {help lines, black!10}
77.4.9
Styling Ticks and Grid Lines: Styling Ticks and Tick Labels
Styling ticks and tick labels is somewhat similar to styling grid lines. Let us start with the tick mark, that
is, the small line that represents the tick. When this mark is drawn, the following styles are applied:
1. every ticks.
2. every major ticks or every minor ticks or every subminor ticks, depending on the kind of ticks
to be visualized.
3. locally specified options for the individual tick, see Section 77.4.11.
4. tick layer
5. every odd tick or every even tick, see Section 77.4.12.
6. draw
7. styling, see Section 77.4.7.
For the tick label node (the node containing the textual representation of the attribute’s value at the tick
position), the following styles are applied:
1. every ticks.
2. every major ticks or every minor ticks or every subminor ticks, depending on the kind of ticks
to be visualized.
3. locally specified options for the individual tick, see Section 77.4.11.
4. tick node layer
5. every odd tick or every even tick, see Section 77.4.12.
6. styling, see Section 77.4.7.
7. node styling, see Section 77.4.7.
802
(style, no value)
/tikz/data visualization/every ticks
This style allows you to configure the appearance of ticks using the style and node style key. Here
is (roughly) the default definition of this style:
node style={
font=\footnotesize,
inner sep=1pt,
outer sep=.1666em,
rounded corners=1.5pt
}
(style, no value)
/tikz/data visualization/every major ticks
The default is
style={line cap=round}, tick length=2pt
(style, no value)
/tikz/data visualization/every minor ticks
The default is
style={help lines,thin, line cap=round}, tick length=1.4pt
(style, no value)
/tikz/data visualization/every subminor ticks
The default is
style={help lines, line cap=round}, tick length=0.8pt
(style, initially on background layer)
/tikz/data visualization/tick layer
Like grid layer, this key specifies on which layer the ticks should be placed.
(style, initially empty)
/tikz/data visualization/tick node layer
Like tick layer, but now for the nodes. By default, tick nodes are placed on the main layer and thus
on top of the data in case that the tick nodes are inside the data.
77.4.10
Styling Ticks and Grid Lines: Exceptional Ticks
You may sometimes wish to style a few ticks differently from the other ticks. For instance, in the axis system
school book axes there should be a tick label at the 0 position only on one axis and then this label should
be offset a bit. In many cases this is easy to achieve: When you add a tick “by hand” using the at or also at
option, you can add any special options in square brackets.
However, in some situations the special tick position has been computed automatically for you, for
instance by the step key or by saying tick=some. In this case, adding a tick mark with the desired options
using also at would cause the tick mark with the correct options to be shown in addition to the tick mark
with the wrong options. In cases like this one, the following option may be helpful:
/tikz/data visualization/options at=hvaluei as[hoptionsi]
(no default)
This key causes the hoptionsi to be executed for any tick mark(s) at hvaluei in addition to any options
given already for this position:
1
0.75
0.5
0.25
0
−0.25
−0.5
−0.75
−1
0
1
2
π
4
5
6
\tikz \datavisualization [
scientific axes,
visualize as smooth line,
x axis={ticks={major={
options at = 3
as [no tick text],
also at
= (pi) as
[{tick text padding=1ex}] $\pi$}}}]
data [format=function] {
var x : interval[0:2*pi];
func y = sin(\value x r);
};
/tikz/data visualization/no tick text at=hvaluei
Shorthand for options at=hvaluei as [no tick text].
803
(no default)
77.4.11
Styling Ticks and Grid Lines: Styling and Typesetting a Value
The at and also at key allow you to provide a comma-separated hlisti of hvalueis where ticks or grid lines
should be placed. In the simplest case, the hvaluei is simply a number. However, the general syntax allows
three different kinds of hvalueis:
1. hvaluei
2. hvaluei as [hlocal optionsi]
3. hvaluei as [hlocal optionsi] htexti
In the first case, the hvaluei is just a number that is interpreted like any other attribute value.
In the second case, where the keyword as is present, followed by some option in square brackets, but
nothing following the closing square bracket, when the tick or grid line at position hvaluei is shown, the hlocal
optionsi are executed first. These can use the style key or the node style key to configure the appearance
of this single tick or grid line. You can also use keys like low or high to influence how large the grid lines or
the ticks are or keys like tick text at low to explicitly hide or show a tick label.
In the third case, which is only important for ticks and not for grid, the same happens as in the second
case, but the text that is shown as tick label is htexti rather than the automatically generated tick label.
This automatic generation of tick labels is explained in the following.
100
90
80
70
60
50
40
30
5
6
7
23
ten
\tikz \datavisualization
[scientific axes=clean,
x axis={length=2.5cm, ticks={major at={
5,
6 as [style=red],
7 as [{style=blue, low=-1em}],
8 as [style=green] $2^3$,
10 as ten
}}},
visualize as line]
data [format=function] {
var x : interval [5:10];
func y = \value x * \value x;
};
A value like “2” or “17” could just be used as htexti to be displayed in the node of a tick label. However,
things are more difficult when the to-be-shown value is 0.0000000015, because we then would typically (but
not always) prefer something like 1.5 · 10−9 to be shown. Also, we might wish a unit to be added like 23m/s.
Finally, we might wish a number like 3.141 to be replaced by π. For these reasons, the data visualization
system does not simply put the to-be-shown value in a node as plain text. Instead, the number is passed
to a typesetter whose job it is to typeset this number nicely using TEX’s typesetting capabilities. The only
exception is, as indicated above, the third syntax version of the at and also at keys, where htexti is placed
in the tick label’s node, regardless of what the typesetting would usually do.
The text produced by the automatic typesetting is computed as follows:
1. The current contents of the key tick prefix is put into the node.
2. This is followed by a call of the key tick typesetting which gets the hvaluei of the tick as its argument
in scientific notation.
3. This is followed by the contents of the key tick suffix.
Let us have a look at these keys in detail:
(no default, initially empty)
/tikz/data visualization/tick prefix=htexti
The htexti will be put in front of every typeset tick:
100
\tikz \datavisualization
[scientific axes, all axes={ticks=few, length=2.5cm},
x axis={ticks={tick prefix=$\langle$, tick suffix=$]$}},
visualize as line]
data [format=function] {
var x : interval [5:10];
func y = \value x * \value x;
};
75
50
25
h6]
h8]
h10]
804
(no default, initially empty)
/tikz/data visualization/tick suffix=htexti
Works like tick prefix. This key is especially useful for adding units like “cm” or “m/s” to every tick
label. For this reason, there is a (near) alias that is easier to memorize:
/tikz/data visualization/tick unit=hroman math texti
(no default)
A shorthand for tick suffix={$\,\rmhroman math texti$}:
100 m/s2
90 m/s2
80 m/s2
70 m/s2
60 m/s2
50 m/s2
40 m/s2
30 m/s2
5s
6s
7s
8s
9 s 10 s
\tikz \datavisualization
[scientific axes, all axes={length=3cm},
x axis={ticks={tick unit=s}},
y axis={ticks={tick unit=m/s^2}},
visualize as line]
data [format=function] {
var x : interval [5:10];
func y = \value x * \value x;
};
(no default)
/tikz/data visualization/tick typesetting=hvaluei
The key gets called for each number that should be typeset. The argument hvaluei will be in scientific
notation (like 1.0e1 for 10). By default, this key applies \pgfmathprintnumber to its argument. This
command is a powerful number printer whose configuration is documented in Section 92.
You are invited to code underlying this key so that a different typesetting mechanism is used. Here is
a (not quite finished) example that shows how, say, numbers could be printed in terms of multiples of
π:
1
0
0.5π
1π
1.5π
2π
−1
\def\mytypesetter#1{%
\pgfmathparse{#1/pi}%
\pgfmathprintnumber{\pgfmathresult}$\pi$%
}
\tikz \datavisualization
[school book axes, all axes={unit length=1.25cm},
x axis={ticks={step=(0.5*pi), tick typesetter/.code=\mytypesetter{##1}}},
y axis={include value={-1,1}},
visualize as smooth line]
data [format=function] {
var x : interval [0.5:7];
func y = sin(\value x r);
};
77.4.12
Stacked Ticks
Sometimes, the text of tick labels are so long or so numerous that the text of adjacent tick labels overlap
(or have too little padding):
805
100
\tikz \datavisualization [scientific axes,
all axes={length=2.5cm},
visualize as smooth line]
data [format=function] {
var y : interval[-100:100];
func x = \value y*\value y;
};
50
0
−50
−100
0 2,000
4,000
6,000
8,000
10,000
There are two ways to address this problem:
• One can rotate the labels on horizontal axes:
100
\tikz \datavisualization [scientific axes,
all axes={length=2.5cm},
x axis={ticks={node style={rotate=90, anchor=east}}},
visualize as smooth line]
data [format=function] {
var y : interval[-100:100];
func x = \value y*\value y;
};
50
0
−50
8,000
10,000
6,000
4,000
0
2,000
−100
This is often a good solution, but may be hard to read. Also consider rotating labels only by 45◦ or
30◦ .
• One can specify different shifts of the nodes for the different ticks, whereby the ticks text no longer
overlap.
100
50
0
−50
−100
0
4,000 8,000
2,000 6,000 10,000
\tikz \datavisualization [scientific axes,
all axes={length=2.5cm},
x axis={ticks={major at={0,4000,8000,
2000 as [node style={yshift=-1em}],
6000 as [node style={yshift=-1em}],
10000 as [node style={yshift=-1em}]}}},
visualize as smooth line]
data [format=function] {
var y : interval[-100:100];
func x = \value y*\value y;
};
However, specifying shifts “by hand” in the above way is not always an option, especially when the tick
positions should be computed automatically. Instead, the stack option can be used, which is much
easier to use and gives better results:
100
\tikz \datavisualization [scientific axes,
all axes={length=2.5cm}, x axis={ticks=stack},
visualize as smooth line]
data [format=function] {
var y : interval[-100:100];
func x = \value y*\value y;
};
50
0
−50
−100
0
4,000 8,000
2,000 6,000 10,000
The stack option is actually just a style that gives you access to the general even/odd mechanism for
ticks with labels. Whenever a tick mark is created where a tick label is also to be drawn, two special things
happen:
1. For every odd tick mark, the every odd tick style is executed, for every even tick mark the every
even tick. Here, “odd” and “even” are with respect to the order in which the ticks have been added
to the list of at positions for each major, minor, or subminor tick list, not with respect to the order in
which they will appear on the axis. Thus, when you write
806
ticks={major at={1,2,3,4}, major at={0,-1,-2}, minor at={9,8,7}}
then for 1, 3, 0, and -2 as well as 9 and 7 the key every odd tick will be executed, while every even
tick will be executed for positions 2, 4, -1, and also 8.
2. When a tick node label is shown at the low position of the tick mark, the dimension stored in the
key tick text low even padding is added to the low value. Provided that this padding is not zero
(which is the default), the length of the even tick marks will be increased and the tick label node will
be placed at a greater distance from the axis.
Similar keys exist for padding ticks with labels at high positions and also at even positions.
/tikz/data visualization/tick text low even padding=hdimensioni
(no default, initially 0pt)
When a tick label is shown at the low position of an even tick, the hdistancei is added to the low value,
see also Section 77.5.4.
100
\tikz \datavisualization [scientific axes,
all axes={length=2.5cm},
x axis={ticks={tick text low even padding=-1em}},
visualize as smooth line]
data [format=function] {
var y : interval[-100:100];
func x = \value y*\value y;
};
50
0
−50
−100
0
4,000 8,000
2,000 6,000 10,000
Note that hdimensioni should usually be non-positive.
The following keys work similarly:
/tikz/data visualization/tick text low odd padding=hdimensioni
(no default, initially 0pt)
/tikz/data visualization/tick text high even padding=hdimensioni
(no default, initially 0pt)
/tikz/data visualization/tick text high odd padding=hdimensioni
(no default, initially 0pt)
/tikz/data visualization/tick text odd padding=hdimensioni
(no default)
A shorthand for setting tick text odd low padding and tick text odd high padding at the same
time.
/tikz/data visualization/tick text even padding=hdimensioni
(no default)
A shorthand for setting tick text even low padding and tick text even high padding at the
same time.
/tikz/data visualization/tick text padding=hdimensioni
(no default)
Sets all text paddings to hdimensioni.
(default 1em)
/tikz/data visualization/stack=hdimensioni
Shorthand for tick text even padding=hdimensioni.
100
\tikz \datavisualization [scientific axes,
all axes={length=2.5cm},
x axis={ticks={stack=1.5em}},
visualize as smooth line]
data [format=function] {
var y : interval[-100:100];
func x = \value y*\value y;
};
50
0
−50
−100
0
4,000
2,000
8,000
6,000 10,000
807
(no default)
/tikz/data visualization/stack’=hdimensioni
Shorthand for tick text odd padding=hdimensioni. The difference to stack is that the set of value
that are “lowered” is exactly exchanged with the set of value “lowered” by stack.
100
\tikz \datavisualization [scientific axes,
all axes={length=2.5cm},
x axis={ticks=stack’},
visualize as smooth line]
data [format=function] {
var y : interval[-100:100];
func x = \value y*\value y;
};
50
0
−50
−100
0
2,000 6,000 10,000
4,000 8,000
Note that the above keys have an effect on all tick labels of an axis, also on special ticks that you may
have added using the also at key. When using the stack key, you should specify a tick text padding
explicitly for such keys:
1
0.75
0.5
0.25
0
−0.25
−0.5
−0.75
−1
\tikz \datavisualization
[scientific axes,
x axis={ticks={stack, many, major also at=
{(pi) as [{tick text padding=2.5em}] $\pi$}}},
visualize as smooth line]
data [format=function] {
var x : interval[0:(2*pi)];
func y = sin(\value x r);
};
0
1
0.5
2
1.5
3
2.5
4
3.5
5
4.5
6
5.5
π
77.4.13
Reference: Basic Strategies
/tikz/data visualization/axis options/linear steps
(no value)
This strategy places ticks at positions that are evenly spaced by the current value of step.
In detail, the following happens: Let a be the minimum value of the data values along the axis and let
b be the maximum. Let the current stepping be s (the stepping is set using the step option, see below)
and let the current phasing be p (set using the phase) option. Then ticks are placed all positions i · s + p
that lie in the interval [a, b], where i ranges over all integers.
The tick positions computed in the way described above are mayor step positions. In addition to these, if
the key minor steps between steps is set to some number n, then n many minor ticks are introduced
between each two mayor ticks (and also before and after the last mayor tick, provided the values still
lie in the interval [a, b]). Note that is n is 1, then one minor tick will be added in the middle between
any two mayor ticks. Use a value of 9 (not 10) to partition the interval between two mayor ticks into
ten equally sized minor intervals.
31.68
31.32
30.96
30.6
30.24
18 21 24 27 30 33
\begin{tikzpicture}
\datavisualization
[scientific axes={inner ticks, width=3cm},
x axis={ticks={step=3, minor steps between steps=2}},
y axis={ticks={step=.36}},
visualize as scatter]
data {
x, y
17, 30
34, 32
};
\end{tikzpicture}
808
/tikz/data visualization/axis options/exponential steps
(no value)
This strategy produces ticks at positions that are appropriate for logarithmic plots. It is automatically
selected when you use the logarithmic option with an axis.
In detail, the following happens: As for linear steps let numbers a, b, s, and p be given. Then, mayor
ticks are placed at all positions 10i·s+p that lie in the interval [a, b] for i ∈ Z.
The minor steps are added in the same way as for linear steps. In particular, they interpolate linearly
between mayor steps.
1 · 106
1 · 105
10,000
1,000
100
10
1
77.4.14
31.62
1,000
\begin{tikzpicture}
\datavisualization
[scientific axes,
x axis={logarithmic, length=2cm, ticks={step=1.5}},
y axis={logarithmic, ticks={step=1, minor steps between steps=9}},
visualize as scatter]
data {
x, y
1, 10
1000, 1000000
};
\end{tikzpicture}
Advanced: Defining New Placement Strategies
/tikz/data visualization/axis options/tick placement strategy=hmacroi
(no default)
This key can be used to install a so-called tick placement strategy. Whenever visualize ticks is used
to request some ticks to be visualized, it is checked whether some automatic ticks should be created.
This is the case when the following key is set:
/tikz/data visualization/compute step=hcodei
(no default)
The hcodei should compute a suitable value for the stepping to be used by the hmacroi in the tick
placement strategy.
For instance, the step key sets compute step to \def\tikz@lib@dv@step{#1}. Thus, when
you say step=5, then the desired stepping of 5 is communicated to the hmacroi via the macro
\tikz@lib@dv@step.
Provided compute step is set to some nonempty value, upon visualization of ticks the hmacroi is
executed. Typically, hmacroi will first call the hcodei stored in the key compute step. Then, it should
implement some strategy then uses the value of the computed or desired stepping to create appropriate at
commands. To be precise, it should set the keys major, minor, and/or subminor with some appropriate
at values.
Inside the call of hmacroi, the macro \tikzdvaxis will have been set to the name of the axis for which
default ticks need to be computed. This allows you to access the minimum and the maximum value
stored in the scaling mapper of that axis.
15
12.5
10
7.5
5
2.5
0
2 3
5
7
11
13
\def\silly{
\tikzdatavisualizationset{major={at={
2,3,5,7,11,13}}}
}
\begin{tikzpicture}
\datavisualization [
scientific axes, visualize as scatter,
x axis={tick placement strategy=\silly}
]
data {
x, y
0, 0
15, 15
};
\end{tikzpicture}
809
77.5
Advanced: Creating New Axis Systems
The data visualization library comes with a number of predefined axis systems, like scientific axes=clean,
but it is also possible and to define new axis systems. Doing so involves the following steps:
1. Creating a number of axes.
2. Configuring attributes of these axes like their length or default scaling.
3. Creating visual representations of the axes.
4. Creating visual representations of the ticks and grid lines.
The first step uses new ... axis keys to create new axes, the last steps use visualize ... keys to
create the visual representations of the axes.
Note that the axis system has no control over the actual attribute value ranges and neither over which
ticks need to be drawn. The axis system can only provide good defaults and then specify how the ticks or
labels should be drawn and where on the page – but not at which values.
In the following, as a running example let us develop an axis system our system that does the following:
For the x-axis is looks like a normal scientific axis system, but there are actually two y-axes: One at the left
and one at the right, each using a different attribute, but both coexisting in the same picture.
77.5.1
Creating the Axes
A new axis system is created as a style key with the prefix /tikz/data visualization. Thus, we would
write:
\tikzset{
data visualization/our system/.style={
...
}
}
In our system we need three axis: The x-axis, the left axis and the right axis. Since all of these axes are
Cartesian axes, we write the following:
\tikzset{
data visualization/our system/.style={
new Cartesian axis=x axis,
new Cartesian axis=left axis,
new Cartesian axis=right axis,
x axis={attribute=x},
left axis={unit vector={(0cm,1pt)}},
right axis={unit vector={(0cm,1pt)}},
}
}
As can be seen, we also configure things so that the x-axis will use the x attribute by default (users
can later change this by saying x axis={attribute=hsome other attributei}), but we do not configure the
attributes of the left axis nor the right axis. We also make the left and right axis point upward (the
x axis needs no configuration here since a Cartesian axis points right by default). The reason is the left
would not be a particularly good attribute name and this way we ensure that users have to pick names
themselves (hopefully good ones).
The next step is to define a standard scaling for the axes. Here, we can use the same as for
scientific axes, so we would add the following keys to the definition of our system:
x axis
={length=\pgfkeysvalueof{/tikz/data visualization/scientific axes/width}},
left axis ={length=\pgfkeysvalueof{/tikz/data visualization/scientific axes/height}},
right axis={length=\pgfkeysvalueof{/tikz/data visualization/scientific axes/height}}
We now already have enough to try our system, although we will not yet see any axes or ticks, but we
will see the correct scaling of the attributes. Let us first define a data group:
810
\tikz \datavisualization data group {people and money} = {
data [set=people 1] {
time, people
1900, 1000000000
1920, 1500000000
1930, 2000000000
1980, 3000000000
}
data [set=people 2] {
time, people
1900, 2000000000
1920, 2500000000
1940, 4000000000
2000, 5700000000
}
data [set=money 1] {
time, money
1910, 1.1
1920, 2
1930, 5
1980, 2
}
data [set=money 2] {
time, money
1950, 3
1960, 3
1970, 4
1990, 3.5
}
};
\tikz \datavisualization [
our system,
x axis={attribute=time, length=4cm},
left axis ={attribute=money},
right axis={attribute=people},
visualize as line/.list={people 1, people 2, money 1, money 2},
people 1={style={visualizer color=blue}},
people 2={style={visualizer color=blue!50}},
money 1={style={visualizer color=red}},
money 2={style={visualizer color=red!50}}]
data group {people and money};
77.5.2
Visualizing the Axes
We must now show the axes themselves. For this we can use the visualize axis key:
/tikz/data visualization/axis options/visualize axis=hoptionsi
(no default)
This key is passed to an axis as an option. It causes a visual representation of the axis to be created
during the data visualization. The hoptionsi are used to determine where the axis should be drawn and
how long it should be. We can specify, for instance, that an axis should be drawn at the minimum value
of another axis or where another axis has the value 0.
The goto, high, and low Keys. In our example, the left axis should be shown at the left hand
side. This is the position where the x axis has its minimum value. To specify this, we would use the
following code:
left axis={ visualize axis={ x axis={ goto=min } }
As can be seen, we can pass another axis as an hoptioni to visualize axis, where we pass the following
key to the axis in turn:
/tikz/data visualization/axis options/goto=hvaluei
(no default)
The key can be passed to an axis. It will set the attribute monitored by the axis to the given
hvaluei, which is usually some number. However, hvaluei may also be one of the following, which
causes a special behaviour:
• min: The attribute is set to the minimal value that the attribute has attained along this axis.
811
• max: Like min.
• padded min: This will also set the hattributei monitored by the axis to the same value as
min. Additionally, however, the subkey /data point/hattributei/offset is set to the current
padding for the minimum, see the description of padding min later on. The effect of this is
that the actual point “meant” by the attribute is offset by this padding along the attribute’s
axis.
• padded max: Like padded min.
The right axis would be visualized the same way, only at goto=max. The x-axis actually need to be
visualized twice: Once at the bottom and once at the top. Thus, we need to call visualize axis twice
for this axis:
\tikzset{
data visualization/our system/.append style={
left axis= {visualize axis={x axis=
{goto=min}}},
right axis={visualize axis={x axis=
{goto=max}}},
x axis=
{visualize axis={left axis={goto=min}},
visualize axis={left axis={goto=max}}},
}
}
\tikz \datavisualization [
our system,
x axis={attribute=time, length=4cm},
left axis ={attribute=money},
right axis={attribute=people},
visualize as line/.list={people 1, people 2, money 1, money 2}]
data group {people and money};
There is another key that is similar to goto, but has a slightly different semantics:
/tikz/data visualization/axis options/goto pos=hfractioni
(no default)
The key works like goto, only the hfractioni is not interpreted as a value but as a fraction of the
way between the minimum and the maximum value for this axis.
Suppose that for an axis the attribute range interval is [500, 1000] and the reasonable interval is
[1, 3]. Then for a hfractioni of 0, the mapping process would choose value 1 from the reasonable
interval, for a hfractioni of 1 the position 3 from the reasonable interval, and for a hfractioni or
0.25 the position 1.5 since it is one quarter at the distance from 1 to 3.
Note that neither the attribute range interval nor the transformation function for the attribute
are important for the goto pos option – the hfractioni is computed with respect to the reasonable
interval. Also note that the values of the actual attribute corresponding to the fractional positions
in the reasonable interval are not computed.
\tikzset{
data visualization/our system/.append style={
x axis=
{visualize axis={left axis={goto pos=0.25}},
visualize axis={left axis={goto pos=0.5}}},
}
}
\tikz \datavisualization [
our system,
x axis={attribute=time, length=4cm},
left axis ={attribute=money},
right axis={attribute=people},
visualize as line/.list={people 1, people 2, money 1, money 2}]
data group {people and money};
By default, when an axis is visualized, it spans the set of all possible values for the monitored attribute,
that is, from min to max. However, there are actually two keys that allow you to adjust this:
(no default)
/tikz/data visualization/low=hvaluei
This is the attribute value where the axis visualization starts. The same special values as for goto
are permissible (like min or padded min, but also 0 or 1).
(no default)
/tikz/data visualization/high=hvaluei
Like low, only for where the axis ends.
812
By default, low=min and high=max are set for an axis visualization. Another sensible setting is
low=padded min and high=padded max. The following key provides a shorthand for this:
(no value)
/tikz/data visualization/padded
Shorthand for low=padded min, high=padded max.
As an example, consider the scientific axes=clean. Here, each axis is actually drawn three times:
Once at the minimum, once at the maximum and then once more at the padded minimum.
The axis line. When an axis is drawn, Tik Z does not simply draw a straight line from the low position
to the high position. In reality, the data visualization system uses the two commands \pgfpathdvmoveto
and \pgfpathdvlineto internally. These will replace the straight line by a curve in certain situations.
For instance, in a polar coordinate system, if an axis should be drawn along an angle axis for a fixed
radius, an arc will be used instead of a straight line.
Styling the axis. As can be seen, we now get the axis we want (but without the ticks, visualizing them
will be explained later). The axis is, however, simply a black line. We can style the axis in a manner
similar to styling ticks and grid lines, see Section 77.4.7. In detail, the following styles get executed:
1. axis layer
2. every axis
3. styling
Additionally, even before every axis is executed, low=min and high=max are executed.
(style, initially on background layer)
/tikz/data visualization/axis layer
The layer on which the axis is drawn. See the description of grid layer on page 77.4.8 for details.
(style, no value)
/tikz/data visualization/every axis
Put styling of the axis here. It is usually a good idea to set this style to style={black!50}.
Recall that the styling key is set using the style key, see Section 77.4.7.
\tikzset{
data visualization/our system/.append style={
every axis/.style={style=black!50}, % make this the default
left axis= {visualize axis={x axis=
{goto=min}, style=red!75}},
right axis={visualize axis={x axis=
{goto=max}, style=blue!75}},
x axis=
{visualize axis={left axis={goto=min}},
visualize axis={left axis={goto=max}}},
}
}
\tikz \datavisualization [
our system,
x axis={attribute=time, length=4cm},
left axis ={attribute=money},
right axis={attribute=people},
visualize as line/.list={people 1, people 2, money 1, money 2}]
data group {people and money};
Padding the Axis. When an axis is visualized, it is often a good idea to make it “a little bit longer”
or to “remove it a bit from the border,” because the visualization of an axis should not interfere with
the actual data. For this reason, a padding can be specified for axes:
/tikz/data visualization/axis options/padding min=hdimensioni
(no default)
This is the dimension that is used whenever goto=padded min is used. The hdimensioni is then put
into the offset subkey of the attribute monitored by the axis. When a data point is transformed
by a linear transformer and when this subkey is nonzero, this offset is added. (For an angle axis of a
polar transformer, the hdimensioni is interpreted as an additional angle rather than as an additional
distance). Note that hdimensioni should typically be negative since “adding the hdimensioni” will
then make the axis longer (because it starts at a smaller value). The standard axis systems set the
padding to some default and take its value into account:
813
25
\begin{tikzpicture}
\datavisualization [scientific axes=clean,
x axis={padding min=-1cm},
visualize as smooth line]
data [format=function] {
var x : interval [-3:5];
func y = \value x * \value x;
};
\end{tikzpicture}
20
15
10
5
0
−2
0
2
4
Using padded and using the padded key, we can visualize our axis “a little removed from the actual
data”:
\tikzset{
data visualization/our system/.append style={
all axes= {padding=.5em},
left axis= {visualize axis={x axis=
{goto=padded
right axis={visualize axis={x axis=
{goto=padded
x axis=
{visualize axis={left axis={goto=padded
visualize axis={left axis={goto=padded
}
}
\tikz \datavisualization [
our system,
x axis={attribute=time, length=3cm},
left axis ={attribute=money},
right axis={attribute=people},
visualize as line/.list={people 1, people 2, money
data group {people and money};
/tikz/data visualization/axis options/padding max=hdimensioni
min},
max},
min},
max},
padded}},
padded}},
padded},
padded}},
1, money 2}]
(no default)
Works like padding min, but hdimensioni should typically be positive.
/tikz/data visualization/axis options/padding=hdimensioni
(no default)
Sets both padding min to the negated value of hdimensioni and padding max to hdimensioni.
77.5.3
Visualizing Grid Lines
As explained earlier, the grid key is used to specify at which positions grid lines should be drawn in principle.
However, this key does not actually cause any grid lines to be drawn. Instead, the visualize grid key is
used by the axis system to specify how grid lines are drawn.
/tikz/data visualization/axis options/visualize grid=hoptionsi
(no default)
This key is passed to an axis. It causes grid lines to be drawn at the positions specified by the grid key
for this axis. The hoptionsi govern where and how the grid lines will be drawn.
The direction axis. At first sight, one might expect that the grid lines for an axis should simply
be drawn perpendicular to the axis between the minimum and maximum value of the axis. However,
things are somewhat more difficult in reality:
1. A grid line is supposed to indicate all positions where a certain attribute attains a fixed value. But,
then, a grid line does not really need to be a grid line. Consider for instance a three dimensional
axis system. A “grid line” for the x-coordinate 3 would actually be a “grid plane.”
2. For a polar coordinate system and a fixed radius, this set of positions at a certain radius is not a
straight line, but an arc. For more complicated coordinate systems such as the one arising from
three-dimensional spherical projections, a grid line may well be a fairly involved curve.
The visualize grid command addresses these complications as follows:
1. A grid line is always a line, not a plane or a volume. This means that in the example of a three
dimensional axis system and the x-attribute being 3, one would have to choose whether the grid
line should go “along” the y-axis or “along” the z-axis for this position. One can, however, call the
814
visualize grid command twice, once for each direction, to cause grid lines to be shown for both
directions.
2. A grid line is created by moving to a start position and then doing a lineto to the target position.
However, the “moveto” and “lineto” are done by calling special commands of the data visualization
system. These special commands allow coordinate system to “notice” that the line is along an axis
and will allow them to replace the straight line by an appropriate curve. The polar axes systems
employ this strategy, for instance.
By the above discussion, in order to create a grid line for attribute a having value v, we need to specify
an axis “along” which the line should be drawn. When there are only two axes, this is usually “the other
axis”. This “other axis” is specified using the following key:
/tikz/data visualization/direction axis=haxis namei
(no default)
You must pass this key as an hoptioni each time you use visualize axis. When the grid line is
drawn, the attribute a is set to v and the axis haxis namei’s attribute is set once to the current value
of low and once to high. Then a line is drawn between these two positions using \pgfpathdvlineto.
The low and high keys are the same as the ones used in the visualize axis key.
\tikz \datavisualization [
xyz Cartesian cabinet,
all axes={visualize axis={low=0, style=->}},
x axis={visualize grid={direction axis=y axis}, grid=many},
visualize as scatter]
data {
x, y, z
0, 0, 1
0, 1, 0
2, 2, 2
};
\tikz \datavisualization [
xyz Cartesian cabinet,
all axes={visualize axis={low=0, style=->}, grid=many},
x axis={visualize grid={direction axis=z axis}},
z axis={visualize grid={direction axis=x axis},
visualize grid={direction axis=y axis},},
visualize as scatter]
data {
x, y, z
0, 0, 1
0, 1, 0
2, 2, 2
};
Styling the grid lines. When a grid line is draw, styles are applied as described in Section 77.4.8.
The major, minor, and subminor grid lines. The grid option allows you to specify for each
kind of grid line (major, minor, or subminor) a set of different values for which these grid lines should
be drawn. Correspondingly, it is also possible to configure for each kind of grid line how it should be
drawn. For this, the major, minor, subminor, and also the common keys can be used inside the hoptionsi
of visualize grid. While as option to grid these keys are used to specify at values, as options of
visualize grid they are used to configure the different kinds of grid lines.
Most of the time, no special configuration is necessary since all styling is best done by configuring keys
like every major grid. You need to use a key like major only if you wish to configure for instance the
low or high values of a major grid line differently from those of minor grid lines – are rather unlikely
setting – or when the styling should deviate from the usual settings.
815
\tikz \datavisualization [
xy Cartesian,
all axes={visualize axis={low=0, style=->},
grid={some, minor steps between steps}},
x axis= {visualize grid={
direction axis=y axis,
minor={low=0.25, high=1.75, style=red!50}}},
visualize as scatter]
data {
x, y
0, 0
3, 3
};
Returning to the example of our system with the two axis systems, it is straight-forward to configure
the grid lines of the x-axis: The direction axis is either of the other two axis (they point in the same direction
and they have the same range). For the other two axes, we visualize one grid independently of the other,
using different colors.
\tikzset{
data visualization/our system/.append style={
x axis=
{visualize grid={direction axis=left axis}},
left axis= {visualize grid={direction axis=x axis,
common={style=red!50}}},
right axis={visualize grid={direction axis=x axis,
common={style=blue!50}}},
}
}
\tikz \datavisualization [
our system,
x axis={attribute=time, length=3cm, grid=many},
left axis ={attribute=money, grid=some},
right axis={attribute=people, grid=few},
visualize as line/.list={people 1, people 2, money 1, money 2}]
data group {people and money};
77.5.4
Visualizing the Ticks and Tick Labels
/tikz/data visualization/axis options/visualize ticks=hoptionsi
(no default)
Visualizing a tick involves (possibly) drawing a tick mark and adding (possibly) the tick node. The
process is similar to visualize grid: Users use the ticks key to configure how many ticks they would
like for an axis and at which positions. The axis system uses the visualize ticks key to specify where
these ticks should actually be shown.
Unlike grid lines, which are typically only visualized once for each combination of an axis and a direction
axis, tick marks might be visualized at different places for the same axis. Consider for instance the
scientific axes:
4
\tikz \datavisualization [scientific axes, all axes={length=3cm},
x axis={ticks={stack}},
visualize as smooth line]
data [format=function] {
var x : interval [0:2];
func y = \value x*\value x;
};
3
2
1
0
0
0.5
1
1.5
2
0.25 0.75 1.25 1.75
Have a look at the ticks on the y-axis: There are ticks at values 0, 1, 2, 3, and 4. These are visualized
both at the left side (where the tick nodes are also shown) and additionally also at the right side, but
only as small marks. Similarly, the ticks on the x-axis appear at the bottom, but also (in much simpler
versions) at the top. Both for the x-axis and for the y-axis the visualize ticks key was called twice.
The tick marks. Drawing a tick mark is quite similar to visualizing a grid line; indeed a tick mark can
be thought of as a “mini grid line”: Just like a grid line it “points a long an axis.” However, a tick will
816
always be a short straight line – even when the coordinate system is actually twisted (experimentation
has shown that ticks that follow the curvature of the coordinate system like grid lines are hard to
recognize). For this reason, the low and high keys have a different meaning from the one used with
the visualize grid key. In detail to configure the size and position of a tick mark for the value v of
attribute a, proceed as follows:
• The visualize ticks key will have setup attribute a to be equal to v.
• You should now use the goto or goto pos key together with all other axes to configure at which
position with respect to these other options the tick mark should be shown. For instance, suppose
we want tick marks in our system for the x-axis at the bottom and at the top. This corresponds
to once setting the left axis to its minimal value and once to its maximal value:
\tikzset{
data visualization/our system/.append style={
x axis={visualize ticks={direction axis=left axis, left axis={goto=min}},
visualize ticks={direction axis=left axis, left axis={goto=max}},
}
}
}
\tikz \datavisualization [
our system,
x axis={attribute=time, length=3cm, ticks=many},
left axis ={attribute=money},
right axis={attribute=people},
visualize as line/.list={people 1, people 2, money 1, money 2}]
data group {people and money};
• In the above example, we may wish to shorten the ticks a bit at the bottom and at the top. For
this, we use the low and high key:
/tikz/data visualization/low=hdimensioni
(no default)
When used with the visualize ticks option, the low key contains a dimension that specifies
the extend of the tick going “toward the minimum” of the direction axis. More precisely, when
a tick mark is visualized, a unit tangent vector at the current data point in the direction of
the direction axis is computed and this vector is multiplied by hdimensioni to compute the
start position of the tick line. The end position is given by this vector times the high value.
Note that the hdimensioni should usually be negative for the low key and positive for the
high key.
For tick marks where a tick label node is shown, the hdimensioni is increased by the current
values of keys like tick text even low padding, see Section 77.4.12 for details.
/tikz/data visualization/high=hdimensioni
(no default)
Like low.
/tikz/data visualization/tick length=hdimensioni
(no default)
Shorthand for low=-hdimensioni, high=hdimensioni.
What we want to happen is that in the upper visualization of the ticks the low value is 0pt, while
in the lower one the high value is 0pt:
\tikzset{
data visualization/our system/.append style={
x axis={
visualize ticks={direction axis=left axis,high=0pt,left axis={goto=min}},
visualize ticks={direction axis=left axis,low=0pt,left axis={goto=max}},
}
}
}
\tikz \datavisualization [
our system,
x axis={attribute=time, length=3cm, ticks=many},
left axis ={attribute=money},
right axis={attribute=people},
visualize as line/.list={people 1, people 2, money 1, money 2}]
data group {people and money};
817
In order to style the tick mark, use the styling mechanism that is detailed in Section 77.4.9.
The tick label node. At certain tick positions, we may wish to add a node indicating the value of
the attribute at the given position. The visualize ticks command has no influence over which text
should be shown at a node – the text is specified and typeset as explained in Section 77.4.11.
Each time visualize ticks, for each tick position up to two tick label nodes will be created: One at
the low position and one at the high position. The following keys are used to configure which of these
cases happen:
/tikz/data visualization/tick text at low=htrue or falsei
(default true)
Pass this option to visualize ticks when you want tick label nodes to be placed at the low
position of each tick mark.
1,920
1,960
2,000
1,900
1,940
1,980
1,900
1,940
1,980
1,920
1,960
2,000
\tikzset{
data visualization/our system/.append style={
x axis={
visualize ticks={direction axis=left axis, left axis={goto=min},
high=0pt, tick text at low, stack},
visualize ticks={direction axis=left axis, left axis={goto=max},
low=0pt, tick text at high, stack}
}
}
}
\tikz \datavisualization [
our system,
x axis={attribute=time, length=3cm, ticks=some},
left axis ={attribute=money},
right axis={attribute=people},
visualize as line/.list={people 1, people 2, money 1, money 2}]
data group {people and money};
/tikz/data visualization/tick text at high=htrue or falsei
(default true)
Like tick text at low.
(no value)
/tikz/data visualization/no tick text
Shorthand for tick text at low=false, tick text at high=false.
100
90
80
70
60
50
40
30
\tikz \datavisualization [scientific axes, all axes={length=3cm},
x axis={ticks={
major also at={6.5 as [no tick text]}}},
visualize as smooth line]
data [format=function] {
var x : interval [5:10];
func y = \value x * \value x;
};
5
6
7
8
9
10
When a tick label node is to be placed at the low or the high position, the next step is to determine the
exact position and the correct anchor of the node. This is done as follows:
• In order to compute an appropriate anchor, the tick mark is considered: This is a short line
pointing in a certain direction. For a tick label node at the low position, the anchor attribute is
setup in such a way that the node label will be below the low position when the tick mark direction
points up, it will be to the right when the direction points left, above when it points down, and so
on also for diagonal directions. Similarly, for the high position, when the direction points up, the
node will be placed above the tick mark and so on.
This computation is done automatically.
• The tick label node is styled. The styles that are applied are described in Section 77.4.9.
• A tick label node for the low position is usually anchored at this low position, but an additional
padding will be added as described in Section 77.4.12.
818
77.5.5
Visualizing the Axis Labels
The label option can be used with an axis to specify a text should be shown next to the axis to indicates
which attribute this axis refers to. Like ticks or grid, the label option does not actually draw the label,
this is the job of the visualize label key, which is configured by the axis system.
/tikz/data visualization/axis options/visualize label=hoptionsi
(no default)
The hoptionsi should be used to configure a “good place” for the axis label. Usually, you will use the
goto or the goto pos key.
For the example of our system, we would like the label of the x axis to be placed below at the middle
of the axis, so we use goto pos=.5 to determine this position. Concerning the other axes, we want it
to be placed at the minimum position of the left axis with a lot of padding.
time
\tikzdatavisualizationset{
our system/.append style={
x axis={visualize label={
x axis={goto pos=.5},
left axis={padding=1.5em, goto=padded min}}}
}
}
\tikz \datavisualization [
our system,
x axis={attribute=time, ticks=some, label},
left axis ={attribute=money},
right axis={attribute=people},
visualize as line/.list={
people 1, people 2, money 1, money 2}]
data group {people and money};
In the above example, the padding of 1.5em was rather arbitrary and “suboptimal”. It would be outright
wrong if the labels on the x axis were larger or if they were missing. It would be better if the vertical
position of the x axis label were always “below” all other options. For such cases a slightly strange
approach is useful: You position the node using node style={at=...} where at is now the normal Tik Z
option that is used to specify the position of a node. Inside the ..., you specify that the horizontal
position should be the bottom of up-to-now-constructed data visualization and the vertical position
should be at the “origin,” which is, however, the position computed by the goto keys for the axes:
Year
\tikzdatavisualizationset{
our system/.append style={
x axis={visualize label={
x axis={goto pos=.5},
node style={
at={(0,0 |- data visualization bounding box.south)},
below
} } } } }
\tikz \datavisualization [
our system,
x axis={attribute=time, ticks=some, label=Year},
left axis ={attribute=money},
right axis={attribute=people},
visualize as line/.list={
people 1, people 2, money 1, money 2}]
data group {people and money};
Two additional keys are useful for positioning axis labels:
/tikz/data visualization/axis option/anchor at min
(no value)
When passed to an axis, this key sets the anchor so that a node positioned at either the min or the
padded min value of the axis will be placed “nicely” with respect to the axis. For instance, if the
axis points upwards from the min value to the max value, the anchor would be set to north since
this gives a label below the axis’s start. Similarly, if the axis points right, the anchor would be set
to east, and so on.
/tikz/data visualization/axis option/anchor at max
Like anchor at min.
819
(no value)
77.5.6
The Complete Axis System
Here is the code for the complete axis system developed above and an example of how it is used:
\tikzdatavisualizationset{ our system/.style={
% The axes
new Cartesian axis=x axis,
new Cartesian axis=left axis,
new Cartesian axis=right axis,
% The directions of the axes
all axes={padding=.5em},
left axis={unit vector={(0cm,1pt)}}, right axis={unit vector={(0cm,1pt)}},
% The default attributes, other attributes must be configured
x axis={attribute=x},
% The lengths of the axes
x axis
={length=\pgfkeysvalueof{/tikz/data visualization/scientific axes/width}},
left axis ={length=\pgfkeysvalueof{/tikz/data visualization/scientific axes/height}},
right axis={length=\pgfkeysvalueof{/tikz/data visualization/scientific axes/height}},
% The styling of the axes
every axis/.style={style=black!50}, % make this the default
% Visualizing the axes themselves
left axis= {visualize axis={x axis=
{goto=padded min}, style=red!75, padded}},
right axis={visualize axis={x axis=
{goto=padded max}, style=blue!75,padded}},
x axis=
{visualize axis={left axis={goto=padded min}, padded},
visualize axis={left axis={goto=padded max}, padded}},
% Visualizing the grid, when requested
x axis=
{visualize grid={direction axis=left axis}},
left axis= {visualize grid={direction axis=x axis, common={style=red!50}}},
right axis={visualize grid={direction axis=x axis, common={style=blue!50}}},
% Visualizing the ticks, when requested
left axis={visualize ticks={style={red!50!black}, direction axis=x axis,
x axis={goto=padded min}, high=0pt, tick text at low}},
right axis={visualize ticks={style={blue!80!black}, direction axis=x axis,
x axis={goto=padded max}, low=0pt, tick text at high}},
x axis={visualize ticks={direction axis=left axis, left axis={goto=padded min}, high=0pt,
tick text at low},
visualize ticks={direction axis=left axis, left axis={goto=padded max}, low=0pt}},
% By default, there are ticks on all axes
all axes={ticks},
% Visualizing the axis labels, when requested
x axis={visualize label={x axis={goto pos=.5}, node style={
at={(0,0 |- data visualization bounding box.south)}, below}}},
left axis={visualize label={left axis={goto pos=.5}, node style={
at={(0,0 -| data visualization bounding box.west)}, rotate=90, anchor=south, red!50!black}}},
right axis={visualize label={right axis={goto pos=.5}, node style={
at={(0,0 -| data visualization bounding box.east)}, rotate=-90, anchor=south, blue!80!black}}},
}}
$5.00
5,000,000,000
4,000,000,000
$3.00
3,000,000,000
$2.00
2,000,000,000
$1.00
1,000,000,000
0
$0.00
1900
1920
1940
1960
1980
2000
Year
820
Population
Spending
$4.00
\tikz \datavisualization [
our system,
x axis={attribute=time, label=Year,
ticks={tick text padding=2pt, style={/pgf/number format/set thousands separator=}}},
left axis={attribute=money, label=Spending,
padding min=0, include value=0, grid,
ticks={tick prefix=\$, style={/pgf/number format/fixed,
/pgf/number format/fixed zerofill, /pgf/number format/precision=2}}},
right axis={attribute=people,
label=Population,
padding min=0, include value=0,
ticks={style=/pgf/number format/fixed}},
visualize as line/.list={
people 1, people 2, money 1, money 2},
people 1={style={visualizer color=blue}},
people 2={style={visualizer color=blue!50}},
money 1={style={visualizer color=red}},
money 2={style={visualizer color=red!50}} ]
data group {people and money};
77.5.7
Using the New Axis System Key
The axis system our system that we developed in the course of the previous section is not yet “configurable.”
The only configuration that was possible was to “misuse” the width and height keys of the scientific axes.
In order to make our system configurable so that we can say our system=hoptionsi, where hoptionsi
are executed with the path prefix
/tikz/data visualization/our system
we can use the following key:
/tikz/data visualization/new axis system={haxis system namei}{haxis setupi}{hdefault optionsi}
{happlication optionsi}
(no default)
The new axis system key takes four parameters. The first one, hsystem namei, is the name of the
to-be-created axis system, our system in our case. The new axis system will create the following new
key:
/tikz/data visualization/haxis system name i=hoptionsi
(no default)
When the key haxis system namei is used, the following keys will be executed in the following order:
1. The haxis setupi with the path prefix /tikz/data visualization/.
2. The hdefault optionsi with the same path prefix.
3. The following style:
/tikz/data visualization/every haxis system name i
(style, no value)
Even though this style has the path prefix /tikz/data visualization itself, the keys
stored in this style will be executed with the path prefix /tikz/data visualization/haxis
system namei.
4. The hoptionsi with the path prefix /tikz/data visualization/haxis system namei.
5. The happlication optionsi with the path prefix /tikz/data visualization/
Let us now have a look at what all of this means. First, the haxis setupi will contain all options that
setup the axis system in all ways that need not be configured. For instance, the haxis setupi for the
scientific axes will create an x axis and also a y axis (because these are always present), but will
not setup the label visualization (because this can be configured in different ways). For our system,
which cannot be configured at all, we would place all of our configuration in the haxis setupi.
The hdefault optionsi can be used to pick default values that would usually be passed to the hoptionsi
of the newly created axis system. For instance, for scientific axis, the hdefault optionsi are set to
outer ticks,standard labels, because these are the defaults.
Finally, the happlication optionsi can be used to actually apply the configuration that has been chosen
by the hoptionsi. The idea is that hdefault optionsi, hoptionsi, and also every haxis system namei
all have a chance of changing, re-changing and re-setting all sorts of styles and keys. Then, with the
last change “winning,” the resulting setting of a style can be executed, which may then cause a label
visualization to be installed.
821
78
Visualizers
78.1
Overview
In a data visualization a long stream of data points is visualized using visualizers. Recall that it is the job
of the axis systems as described in Section 77 to determine where data points are visualized. It is the job of
the visualizers to determine how they are visualized.
The most basic and common visualizer is the line visualizer. It simply connects subsequent data points
by straight lines to indicate either that the points on these lines interpolate between the real data points
or the straight lines are used to indicate the order in which the data points appear. A different, more
“conservative” visualizer is the scatter visualizer or mark visualizer, which just places a small mark at each
data point. Such a visualizer does not imply any interpolation or ordering between the data points.
Visualizers may, however, also be more complicated. For instance, a visualizer used for a box plot could
visualize a data point as a box with a median value, standard deviation, outliers, and other information; a
rectangle visualizer might visualize data points as larger areas; a projection visualizer might visualize the
projection of data points onto different axes; and so.
Creating a new visualizer is not quite trivial since a new pgf class needs to be implemented. Fortunately,
using visualizers is much simpler: For each kind of visualizer there is a key that allows you to create such a
visualizer. You can then use further keys to configure the visualizer and to connect it to the data.
In a data visualization multiple visualizers may exist at the same time. This happens in different situations:
• A data visualization may contain several independent data sets that are to be visualized. There might
be a line plot, for which a line visualizer is used, and also a scatter plot, for which a scatter visualizer
would be used.
In this case, for each data point only one visualizer will do anything. To achieve this, each data point
has an attribute called visualizer which tells the visualizer objects whether they should “react” to
the data point or not.
• A single data point might be visualized several times. For instance, a scatter visualizer might draw a
mark at the data point’s position on the page and a projection visualizer might draw, additionally, a
mark at the projected position.
78.2
78.2.1
Usage
Using a Single Visualizer
The simplest scenario for using visualizers are data visualizations in which there is only a single data set
that is visualized in one style. In this case, all that needs to be done in order to choose a visualizer is use
one of the options starting with visualize as ... together with the \datavisualization command:
2
2
2
1
1
1
0
1
2
0
% Define a data set:
\tikz \datavisualization
data {
x, y
0, 0
0.5, 2
1, 2
1.5, 1.5
2, 0.5
}};
\tikz \datavisualization
\qquad
\tikz \datavisualization
\qquad
\tikz \datavisualization
1
2
0
1
2
data group {example} = {
[school book axes, visualize as line]
data group {example};
[school book axes, visualize as smooth line] data group {example};
[school book axes, visualize as scatter]
822
data group {example};
Methods for styling visualizers are discussed in Section 78.2.3.
78.2.2
Using Multiple Visualizers
A data visualization may contain multiple data groups and for each data set we might wish to use a different
visualizer. In this case, we need some way of telling the data visualization engine to which visualizer should
be used with the different data points.
To solve this problem, you can name a visualizer. The visualizer’s name can then both be used to
configure the visualizer and also to indicate that data points “belong” to the visualizer.
Naming a visualizer is quite simple: The visualize as ... keys actually take a single parameter, which
is the name of the visualizer. For instance, the following code creates three visualizers, named sin, cos, and
tan:
visualize as line=sin,
visualize as line=cos,
visualize as scatter=tan
(When you just say visualize as line without providing a name, the name line is chosen as a default,
for visualize as scatter the name scatter is the default and so.)
In order to indicate which data points should be visualized by which of these visualizers, the following
key is important:
(no value)
/data point/set
A visualizer will only act on a data point when its name matches the value of this key. Initially, this
key is set to the last visualizer created, so if there is only one, there is no need to set or worry about
this key.
Since the set key has the path prefix /data point, it can be set like any other attribute of a data key:
4
3
2
1
0
−1
0
1
2
3
4
\tikz \datavisualization
[scientific axes=clean,
visualize as line=sin,
visualize as line=cos,
visualize as scatter=tan]
data {
x, y, set
0, 0, sin
1, 1, sin
2, 0, sin
3, -1, sin
4, 0, sin
0, 1, cos
1, 0, cos
0, 0, tan
1, 1, tan
2, 2, tan
3, 4, tan
2, -1, cos
3, 0, cos
4, 1, cos
};
As can be seen, the data points with the same set attribute do not need to be consecutive.
The above method of specifying the visualizer works nicely, but in most cases it would be more natural
to keep the set attribute out of the table. This is easy to achieve by using multiple data and using the
following key:
(no default)
/pgf/data/set=hnamei
Shorthand for /data point/set=hnamei.
823
1
0.5
0
−0.5
−1
0
1
2
3
4
\tikz \datavisualization
[scientific axes=clean,
visualize as line=sin,
visualize as line=cos]
data [set=sin] {
x, y
0, 0
1, 1
2, 0
3, -1
4, 0
}
data [set=cos] {
x, y
0, 1
1, 0
2, -1
3, 0
4, 1
};
When you need to visualize several similar things in a single plot (like ten lines that all get visualized
by visualize as line), it is somewhat cumbersome having to write this ten times. In this case you can
shorten your code by making use of the .list key handler: When you add it to a key, the “value” passed to
the key is parsed as a list of values. The key is then executed once for each of these values:
6
4
2
0
0
78.2.3
2
4
6
8
\tikz \datavisualization
[scientific axes=clean,
visualize as line/.list={sin,
data [set=sin, format=function]
var x : interval[0:3*pi];
func y = sin(\value x r);
}
data [set=cos, format=function]
var x : interval[0:3*pi];
func y = cos(\value x r);
}
data [set=tan, format=function]
var x : interval[0:pi/2.2];
func y = tan(\value x r);
};
cos, tan}]
{
{
{
Styling a Visualizer
In order to style a visualizer that has been created using for instance visualize as line=hvisualizer namei,
you can use the following key:
/tikz/data visualization/hvisualizer name i=hoptionsi
(no default)
For each visualizer, a key of the same name is created with the path prefix /tikz/data visualization.
This key takes the hoptionsi and executes them with the path prefix
/tikz/data visualization/visualizer options/
These options are then used to configure the appearance of the current visualizer. (This is quite similar
to the way options are passed to an axis in order to configure the axis.) Possible options include style,
but also label in legend and label in data. The latter two options are discussed in Section 79.3,
the first option below.
824
1
\tikz \datavisualization
[scientific axes=clean,
visualize as smooth line/.list={sin, cos},
sin={style=red},
cos={style=blue}]
data [set=sin, format=function] {
var x : interval[0:3*pi];
func y = sin(\value x r);
}
data [set=cos, format=function] {
var x : interval[0:3*pi];
func y = cos(\value x r);
};
0.5
0
−0.5
−1
0
2
4
6
8
/tikz/data visualization/visualizer options/style=hoptionsi
(no default)
The hoptionsi given to this key should be normal Tik Z options. They will be executed when the
visualizer is used.
1
\tikz \datavisualization
[scientific axes=clean,
visualize as smooth line=sin,
sin={style={red, densely dotted}},
visualize as smooth line=cos,
cos={style={mark=x}},
]
data [set=sin, format=function] {
var x : interval[0:3*pi];
func y = sin(\value x r);
}
data [set=cos, format=function] {
var x : interval[0:3*pi];
func y = cos(\value x r);
};
0.5
0
−0.5
−1
0
2
4
6
8
When you have multiple visualizers in a single data visualization, you can use the style option with
each visualizer to configure their different appearances as in the above example. However, it is usually
much better (and easier) to use a style sheet, see Section 79.
1
0.5
0
−0.5
−1
x
0
2
4
sin x
cos x
6
sin 2x
cos 2x
8
\tikz \datavisualization
[scientific axes={clean, end labels},
x axis={label=$x$}, y axis={grid={major also at=0}},
visualize as smooth line/.list={sin,cos,sin 2,cos 2},
legend={below, rows=2},
sin={label in legend={text=$\sin x$}},
cos={label in legend={text=$\cos x$}},
sin 2={label in legend={text=$\sin 2x$}},
cos 2={label in legend={text=$\cos 2x$}},
style sheet=strong colors]
data [set=sin, format=function] {
var x : interval[0:3*pi];
func y = sin(\value x r);
}
data [set=cos, format=function] {
var x : interval[0:3*pi];
func y = cos(\value x r);
}
data [set=sin 2, format=function] {
var x : interval[0:3*pi];
func y = sin(2*\value x r);
}
data [set=cos 2, format=function] {
var x : interval[0:3*pi];
func y = cos(2*\value x r);
};
/tikz/data visualization/visualizer options/ignore style sheets
(no value)
This option, which should be passed to a visualizer after its creation before another visualizer is created,
causes style sheets not to apply to the visualizer (but the style option will still have an effect). This
allows you to create visualizers that are used for special purposes and that do not “take part” in the
825
usual styling. For instance, a visualizer might be used internally to depict a regression line, even though
the regression line itself should not participate in the usual styling by, say, dashing or different coloring.
In addition to the options passed to a visualizer via style, the following also gets executed when a
visualizer is used:
(style, no value)
/tikz/data visualization/every visualizer
This style is used with every visualizer. Note that it should contain normal Tik Z keys.
1
0.75
0.5
0.25
0
−0.25
−0.5
−0.75
−1
\tikz \datavisualization
[scientific axes=clean,
every visualizer/.style={dashed},
visualize as smooth line]
data [format=function] {
var x : interval[0:3*pi];
func y = sin(\value x r);
};
0
78.3
2
4
6
8
Reference: Basic Visualizers
78.3.1
Visualizing Data Points Using Lines
/tikz/data visualizers/visualize as line=hvisualizer namei
(default line)
Creates a new visualizer named hvisualizer namei. Basically, this visualizer connects all data points for
which the /data point/set attribute equals hvisualizer namei by a line that is styled by the visualizer’s
style.
In more detail, the following happens:
1. A new object is created (of class plot handler visualizer) that is configured to collect the
canvas positions of all data points whose set attribute equals hvisualizer namei.
2. During the end of the data visualization, pgf’s plotting mechanism (see Section 107) is used to
plot the stream of recorded data points.
This means that, in principle, all of the plot handlers available in Tik Z could be used for the
visualization (such as the smooth handler). However, some plot handlers such as, say, the xcomb
are unsuitable as plot handlers since they do not support the advanced axis handling done by the
data visualization engine. Because of this (and also for other reasons), you cannot set the plot
handler directly, but must use one of the options like straight line, smooth line and others,
documented in a moment.
3. Additionally, plot marks can be drawn at the collected data points. Here, all of the options available
to Tik Z for drawing plot marks are available. To configure them, all options offered by Tik Z for
configuring marks are available such as mark repeat:
\tikz \datavisualization
[scientific axes=clean,
visualize as line=my data,
my data={style={mark=x, mark repeat=3}}]
data [format=function] {
var x : interval [0:pi] samples 10;
func y = sin(\value x r);
};
0.8
0.6
0.4
0.2
0
0
0.5
1
1.5
2
2.5
3
The line visualizer also provides a method of dealing with gaps in a line. Take for instance the function
f (x) = tan x. When this function is plotted over the interval [0, π], then the function will go to ±∞ at
π/2. When we plot this, we might plot the function in the interval [0, π2 − ] and then
continue in the
π
π
interval [ π2 + , π]. However, we do not
want
the
point
at
coordinate
−
,
tan(
−
)
to be connected
2
2
to the coordinate π2 + , tan( π2 + ) by a line. Rather, there should be a “gap” or a “jump” between
these coordinates. To achieve this, the following key can be used:
826
(default true, initially empty)
/data point/outlier=hvaluei
When this key is set to anything non-empty value, a visualizer will consider this data point to be
an “outlier.” For a line visualizer this means that the point is not shown and that the current line
ends at the previous data point and a new line starts at the next data point.
7.5
5
2.5
0
−2.5
−5
−7.5
0
0.5
1
1.5
2
2.5
3
\tikz \datavisualization
[scientific axes=clean, x axis={grid={major at=(pi/2)}},
visualize as smooth line]
data [format=function] {
var x : interval[0:pi/2-0.1];
func y = tan(\value x r);
}
data point [outlier]
data [format=function] {
var x : interval[pi/2+0.1:pi];
func y = tan(\value x r);
};
/tikz/data visualizers/visualize as smooth line=hvisualizer namei
(default line)
A shorthand visualize as line=hvisualizer namei followed hvisualizer namei=smooth line.
/tikz/data visualization/visualizer options/straight line
(no value)
Causes the data points to be connected by straight lines.
0.5
0
−0.5
−0.5
0
0.5
1
\tikz [scale=.55] \datavisualization
[scientific axes=clean, all axes={ticks=few},
visualize as smooth line=my data, my data={straight line}]
data [format=function] {
var t : interval [0:4] samples 5;
func x = cos(\value t r);
func y = sin(\value t r);
};
/tikz/data visualization/visualizer options/straight cycle
(no value)
Causes the data points to be connected by a polygon.
0.5
0
−0.5
−0.5
0
0.5
1
\tikz [scale=.55] \datavisualization
[scientific axes=clean, all axes={ticks=few},
visualize as smooth line=my data, my data={straight cycle}]
data [format=function] {
var t : interval [0:4] samples 5;
func x = cos(\value t r);
func y = sin(\value t r);
};
/tikz/data visualization/visualizer options/polygon
(no value)
This is an alias for straight cycle.
/tikz/data visualization/visualizer options/smooth line
(no value)
Causes the data points to be connected by a line that is smoothed at the joins:
0.5
0
−0.5
−0.5
0
0.5
1
\tikz [scale=.55] \datavisualization
[scientific axes=clean, all axes={ticks=few},
visualize as smooth line=my data, my data={smooth line}]
data [format=function] {
var t : interval [0:4] samples 5;
func x = cos(\value t r);
func y = sin(\value t r);
};
/tikz/data visualization/visualizer options/smooth cycle
Causes the data points to be connected by a circular line that is smoothed at the joins:
827
(no value)
\tikz [scale=.55] \datavisualization
[scientific axes=clean, all axes={ticks=few},
visualize as smooth line=my data, my data={smooth cycle}]
data [format=function] {
var t : interval [0:4] samples 5;
func x = cos(\value t r);
func y = sin(\value t r);
};
0.5
0
−0.5
−0.5
0
0.5
1
/tikz/data visualization/visualizer options/gap line
(no value)
This key causes the data points to be connected by lines that “do not quite touch” the data points. This
is implemented by using the \pgfplothandlergaplineto, see Section 62.5.
0.5
0
−0.5
−0.5
0
0.5
1
\tikz [scale=.55] \datavisualization
[scientific axes=clean, all axes={ticks=few},
visualize as smooth line=my data, my data={gap line}]
data [format=function] {
var t : interval [0:4] samples 5;
func x = cos(\value t r);
func y = sin(\value t r);
};
/tikz/data visualization/visualizer options/gap cycle
(no value)
Like gapped line, only with a cycle:
0.5
0
−0.5
−0.5
0
0.5
1
\tikz [scale=.55] \datavisualization
[scientific axes=clean, all axes={ticks=few},
visualize as smooth line=my data, my data={gap cycle}]
data [format=function] {
var t : interval [0:4] samples 5;
func x = cos(\value t r);
func y = sin(\value t r);
};
/tikz/data visualization/visualizer options/no lines
(no value)
Suppresses the line. This option only makes sense when the mark option is used.
0.5
0
−0.5
−0.5
78.3.2
0
0.5
1
\tikz [scale=.55] \datavisualization
[scientific axes=clean, all axes={ticks=few},
visualize as smooth line=my data, my data={no lines, style={mark=x}}]
data [format=function] {
var t : interval [0:4] samples 5;
func x = cos(\value t r);
func y = sin(\value t r);
};
Visualizing Data Points Using Marks
/tikz/data visualizers/visualize as scatter=hvisualizer namei
(default scatter)
A shorthand visualize as line=hvisualizer namei followed hvisualizer namei=no lines and setting
the style of the visualizer so that is will use mark=x (plus some size adjustments) to draw marks at the
data points.
\tikz \datavisualization
[scientific axes=clean,
visualize as scatter]
data [format=function] {
var x : interval [0:pi] samples 10;
func y = sin(\value x r);
};
0.8
0.6
0.4
0.2
0
0
0.5
1
1.5
2
2.5
3
828
78.4
Advanced: Creating New Visualizers
Creating a new visualizer is a two-stage process that does, unfortunately, require in-depth knowledge of the
data visualization backend:
1. First, you need to create a new class using \pgfooclass whose instances react to the signal visualize
datapoint signal. This requires detailed knowledge of the data visualization engine, see Section 81.
2. Second, you should provide keys on the Tik Z level for creating the necessary objects. These keys invoke
the key new visualizer internally.
/tikz/data visualization/new visualizer={hnamei}{hoptionsi}{hlegend entry optionsi} (no default)
This key configures a new visualizer named hnamei. This entails the following actions:
• The key /tikz/data visualization/hnamei is created. As described earlier, this key can be used
to pass for instance style options to the visualizer.
• The style key /tikz/data visualization/visualizers/hnamei/styling is created and made
empty. This is the key in which the style key will store the options passed to the visualizer.
• The style key /tikz/data visualization/visualizers/hnamei/label in legend options is
set to hlegend entry optionsi. These options are used to configure how the visualizer should be
rendered in a legend, see Section 79.9.9 for details.
• The key /data point/set/hnamei is set to a number that is increased for each visualizer in the
current data visualization. This number is important for style sheets, see Section 79.
• The key /data point/hnamei/execute at begin is set to code that creates a {scope} that executes the following styles as options:
1.
2.
3.
4.
The
The
The
The
hoptionsi passed to the new visualizer key.
every visualizer style.
styling from the currently active style sheets, see Section 79.
styling stored in the styling key mentioned above.
• The key /data point/hnamei/execute at end is set to code that will finish all paths that may
have been created by the visualizer and closes the scope.
All of the above mean the following in practice:
• Inside a new visualize as ... key, you pass the name of the to-be-created to new visualizer as
the first parameter and any special default styling setup of the visualizer as the second parameter.
• The new visualize as ... key should also create a visualizer object using new object.
• When this object finally is about to create the actual visualization, it should surround the code by
invoking the code stored in the execute at begin and the execute at end keys of the visualizer.
Everything else is usually taken care of by the new visualizer key automatically.
As an example, let us create a simple visualizer that creates a circle whose radius is dictated by the
radius attribute. To keep things simple in this example, this attribute cannot be configured.
First, we need the visualizer class. For this example I have boiled it down to a minimum:
829
\pgfooclass{circle visualizer}
{
% Stores the name of the visualizer. This is needed for filtering and configuration
\attribute name;
% The constructor. Just setup the attribute.
\method circle visualizer(#1) { \pgfooset{name}{#1} }
% Connect to visualize signal.
\method default connects() {
\pgfoothis.get handle(\me)
\pgfkeysvalueof{/pgf/data visualization/obj}.connect(\me,visualize,visualize datapoint signal)
}
% This method is invoked for each data point. It checks whether the data point belongs to the correct
% visualizer and, if so, calls the macro \dovisualization to do the actual visualization.
\method visualize() {
\pgfdvfilterpassedtrue
\pgfdvnamedvisualizerfilter
\ifpgfdvfilterpassed
\dovisualization
\fi
}
}
The \dovisualization method must now do the correct visualization.
\def\dovisualization{
\pgfkeysvalueof{/data point/\pgfoovalueof{name}/execute at begin}
\pgfpathcircle{\pgfpointdvdatapoint}{\pgfkeysvalueof{/data point/radius}}
% \pgfusepath is done by |execute at end|
\pgfkeysvalueof{/data point/\pgfoovalueof{name}/execute at end}
}
Finally, we create a visualize as key:
\tikzdatavisualizationset{
visualize as circle/.style={
new object={
when=after survey,
store=/tikz/data visualization/visualizers/#1,
class=circle visualizer,
arg1=#1
},
new visualizer={#1}{%
color=visualizer color,
% a color setup by the style sheet
every path/.style={fill,draw}, % fill and draw the circle by default,
}{}, % let’s ignore legends in this example
/data point/set=#1
},
visualize as circle/.default=circle
}
Now, let’s see how this works:
830
2.5
2
1.5
1
0.5
0
0
0.5
1
1.5
2
2.5
3
\tikz \datavisualization [
scientific axes=clean,
visualize as circle/.list={a, b, c},
style sheet=strong colors]
data [set=a] {
x, y, radius
0, 0, 2pt
1, 1, 3pt
1, 2, 3pt
2, 0, 1pt
}
data [set=b] {
x, y, radius
0.5, 0.5, 5pt
1, 1.5, 2pt
1, 2.5, 3pt
0, 2, 4pt
}
data [set=c] {
x, y, radius
3, 2, 3pt
2.5, 0.5, 4pt
};
831
79
79.1
Style Sheets and Legends
Overview
In many data visualizations, different sets of data need to be visualized in a single visualization. For instance,
in a plot there might be a line for the sine of x and another line for the cosine of x; in another visualization
there might be a set of points representing data from a first experiment and another set of points representing
data from a second experiment; and so on. In order to indicate to which data set a data point belongs, one
might plot the curve of the sine in, say, black, and the curve of the cosine in red; we might plot the data from
the fist experiment using stars and the data from the second experiment using circles; and so on. Finally, at
some place in the visualization – either inside the data or in a legend next to it – the meaning of the colors
or symbols need to be explained.
Just as you would like Tik Z to map the data points automatically onto the axes, you will also typically
wish Tik Z to choose for instance the coloring of the lines automatically for you. This is done using style
sheets. There are at least two good reasons why you should prefer style sheets over configuring the styling
of each visualizer “by hand” using the style key:
1. It is far more convenient to just say style sheet=strong colors than having to individually picking
the different colors.
2. The style sheets were chosen and constructed rather carefully.
For instance, the strong colors style sheet does not pick colors like pure green or pure yellow,
which have very low contrast with respect to a white background and which often lead to unintelligible
graphics. Instead, opposing primary colors with maximum contrast on a white background were picked
that are visually quite pleasing.
Similarly, the different dashing style sheets are constructed in such a way that there are only few and
small gaps in the dashing so that no data points get lost because the dashes are spaced too far apart.
Also dashing patterns were chosen that have a maximum optical difference.
As a final example, style sheets for plot marks are constructed in such a way that even when two plot
marks lie directly on top of each other, they are still easily distinguishable.
The bottom line is that whenever possible, you should use one of the predefined style sheets rather than
picking colors or dashings at random.
79.2
Concepts: Style Sheets
A style sheet is a predefined list of styles such as a list of colors, a list of dashing pattern, a list of plot marks,
or a combinations thereof. A style sheet can be attached to a data point attribute. Then, the value of this
attribute is used with data points to choose which style in the list should be chosen to visualize the data
point.
In most cases, there is just one attribute to which style sheets get attached: the /data point/visualizer
attribute. The effect of attaching a style sheet to this attribute is that each visualizer is styled differently.
For the following examples, let us first define a simple data set:
\tikz \datavisualization data group {function classes} = {
data [set=log, format=function] {
var x : interval [0.2:2.5];
func y = ln(\value x);
}
data [set=lin, format=function] {
var x : interval [-2:2.5];
func y = 0.5*\value x;
}
data [set=squared, format=function] {
var x : interval [-1.5:1.5];
func y = \value x*\value x;
}
data [set=exp, format=function] {
var x : interval [-2.5:1];
func y = exp(\value x);
}
};
832
\tikz \datavisualization [
school book axes, all axes={unit length=7.5mm},
visualize as smooth line/.list={log, lin, squared, exp},
style sheet=strong colors]
data group {function classes};
2
1
−2
−1
0
1
2
−1
\tikz \datavisualization [
school book axes, all axes={unit length=7.5mm},
visualize as smooth line/.list={log, lin, squared, exp},
style sheet=vary dashing]
data group {function classes};
2
1
−2
−1
0
1
2
−1
79.3
Concepts: Legends
A legend is a box that is next to a data visualization (or inside it at some otherwise empty position) that
contains a textual explanation of the different colors or styles used in a data visualization.
Just as it is difficult to get colors and dashing patterns right “by hand,” it is also difficult to get a legend
right. For instance, when a small line is shown in the legend that represents the actual line in the data
visualization, if the line is too short and the dashing is too large, it may be impossible to discern which
dashing is actually meant. Similarly, when plot marks are shown on such a short line, using a simple straight
line may make it hard to read the plot marks correctly.
The data visualization engine makes some effort to make it easy to create high-quality legends. Additionally, it also offers ways of easily adding labels for visualizers directly inside the data visualization, which
is even better than adding a legend, in general.
2
log x
x/2
x2
ex
1
−2
−1
x
0
1
2
−1
2
x/2
1
x2
ex
−2
−1
0
x
1
−1
log x
2
\tikz \datavisualization [
school book axes, all axes={unit length=7.5mm},
x axis={label=$x$},
visualize as smooth line/.list={log, lin, squared, exp},
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
squared={label in legend={text=$x^2$}},
exp=
{label in legend={text=$e^x$}},
style sheet=vary dashing]
data group {function classes};
\tikz \datavisualization [
school book axes,
x axis={label=$x$},
visualize as smooth line/.list={log, lin, squared, exp},
every data set label/.append style={text colored},
log=
{pin in data={text’=$\log x$, when=y is -1}},
lin=
{pin in data={text=$x/2$, when=x is 2,
pin length=1ex}},
squared={pin in data={text=$x^2$, when=x is 1.1,
pin angle=230}},
exp=
{label in data={text=$e^x$, when=x is -2}},
style sheet=vary hue]
data group {function classes};
833
79.4
Usage: Style Sheets
79.4.1
Picking a Style Sheet
To use a style sheet, you need to attach it to an attribute. You can attach multiple style sheets to an
attribute and in this case all of these style sheets can influence the appearance of the data points.
Most of the time, you will attach a style sheet to the set attribute. This has the effect that each different
data set inside the same visualization is rendered in a different way. Since this use of style sheets is the most
common, there is a special, easy-to-remember option for this:
/tikz/data visualization/style sheet=hstyle sheeti
(no default)
Adds the hstyle sheeti to the list of style sheets attached to the set attribute.
\tikz \datavisualization [
school book axes, all axes={unit length=7.5mm},
visualize as smooth line/.list={log, lin, squared, exp},
style sheet=vary thickness and dashing,
style sheet=vary hue]
data group {function classes};
2
1
−2
−1
0
1
2
−1
While the style sheet key will attach a style sheet only to the set attribute, the following key handler
can be used to attach a style sheet to an arbitrary attribute:
Key handler hkeyi/.style sheet=hstyle sheeti
Inside a data visualization you can use this key handler together with an attribute, that is, with a key
having the path prefix /data point. For instance, in order to attach the hstyle sheeti strong colors
to the attribute set, you could write
/data point/set/.style sheet=strong colors
Indeed, the style sheet key is just a shorthand for the above.
The effect of attaching a style sheet is the following:
• A new object is created that will monitor the attribute.
• Each time a special styling key is emitted by the data visualization engine, this object will inspect
the current value of the attribute to which it is attached.
• Depending on this value, one of the styles stored in the style sheet is chosen (how this works,
exactly, will be explained in a moment).
• The chosen style is then locally applied.
In reality, things are a bit more complicated: If the attribute of the data point happens to have a subkey
named in the same way as the value, then the value of is this subkey is used instead of the value itself.
This allows you to “rename” a value.
In a sense, a style sheet behaves much like a visualizer (see Section 78): In accordance with the value of
a certain attribute, the appearance of data points change. However, there are a few differences: First,
the styling of a data point needs to be triggered explicitly and this triggering is not necessarily done
for each data point individually, but only for a whole visualizer. Second, styles can be computed even
when no data point is present. This is useful for instance in a legend since, here, a visual representation
of a visualizer needs to be created independently of the actual data points.
79.4.2
Creating a New Style Sheet
Creating a style sheet works as follows: For each possible value that an attribute can attain we must specify a
style. This is done by creating a style key for each such possible value with a special path prefix and setting
this style key to the desired value. The special path prefix is /pgf/data visualization/style sheets
followed by the name of the style sheet.
834
As an example, suppose we wish to create a style sheet test that makes styled data points red when the
attribute has value foo and green when the attribute has value bar and dashed, blue when the attribute
is foobar. We could then write
/pgf/data visualization/style sheets/test/foo/.style={red},
/pgf/data visualization/style sheets/test/bar/.style={green},
/pgf/data visualization/style sheets/test/foobar/.style={dashed, blue},
We could then attach this style sheet to the attribute code as follows:
/data point/code/.style sheet=test
Then, when /data point/code=foobar holds when the styling signal is raised, the style dashed, blue
will get executed.
A natural question arises concerning the situation that the value of the attribute is not defined as a
subkey of the style sheet. In this case, a special key gets executed:
/pgf/data visualization/style sheets/hstyle sheet i/default style=hvaluei
(style, no default)
This key gets during styling whenever /pgf/data visualization/style sheet/hstyle sheeti/hvaluei
is not defined.
Let us put all of this together in a real-life example. Suppose we wish to create a style sheet that makes
the first data set green, the second yellow and the third one red. Further data sets should be, say, black.
The attribute that we intend to style is the set attribute. For the moment, we assume that the data sets
will be named 1, 2, 3, and so on (instead of, say, experiment 1 or sin or something more readable – we
will get rid of this restriction in a minute).
We would now write:
2
1
0
1
2
\pgfkeys{
/pgf/data visualization/style sheets/traffic light/.cd,
% All these styles have the above prefix.
1/.style={green!50!black},
2/.style={yellow!90!black},
3/.style={red!80!black},
default style/.style={black}
}
\tikz \datavisualization [
school book axes,
visualize as line=1,
visualize as line=2,
visualize as line=3,
style sheet=traffic light]
data point [x=0, y=0, set=1]
data point [x=2, y=2, set=1]
data point [x=0, y=1, set=2]
data point [x=2, y=1, set=2]
data point [x=0.5, y=1.5, set=3]
data point [x=2.25, y=1.75, set=3];
In the above example, we have to name the visualizers 1, 2, 3 and so one since the value of the set
attribute is used both assign data points to visualizers and also pick a style sheet. However, it would be
much nicer if we could name any way we want. To achieve this, we use the special rule for style sheets that
says that if there is a subkey of an attribute whose name is the same name as the value, then the value of
this key is used instead. This slightly intimidating definition is much easier to understand when we have a
look at an example:
835
2
1
0
1
2
% Definition of traffic light keys as above
\begin{tikzpicture}
\datavisualization data group {lines} = {
data point [x=0, y=0,
set=normal]
data point [x=2, y=2,
set=normal]
data point [x=0, y=1,
set=heated]
data point [x=2, y=1,
set=heated]
data point [x=0.5, y=1.5,
set=critical]
data point [x=2.25, y=1.75, set=critical]
};
\datavisualization [
school book axes,
visualize as line=normal,
visualize as line=heated,
visualize as line=critical,
/data point/set/normal/.initial=1,
/data point/set/heated/.initial=2,
/data point/set/critical/.initial=3,
style sheet=traffic light]
data group {lines};
\end{tikzpicture}
Now, it is a bit bothersome that we have to set all these /data point/set/... keys by hand. It turns
out that this is not necessary: Each time a visualizer is created, a subkey of /data point/set with the name
of the visualizer is created automatically and a number is stored that is increased for each new visualizer in
a data visualization. This means that the three lines starting with /data point are inserted automatically
for you, so they can be left out. However, you would need them for instance when you would like several
different data sets to use the same styling:
2
1
0
1
2
% Definition of traffic light keys as above
\tikz \datavisualization [
school book axes,
visualize as line=normal,
visualize as line=heated,
visualize as line=critical,
/data point/set/critical/.initial=1, % same styling as first set
style sheet=traffic light]
data group {lines};
We can a command that slightly simplifies the definition of style sheets:
\pgfdvdeclarestylesheet{hnamei}{hkeysi}
This command executes the hkeysi with the path prefix /pgf/data visualization/style sheets/
hnamei. The above definition of the traffic light style sheet could be rewritten as follows:
\pgfdvdeclarestylesheet{traffic light}{
1/.style={green!50!black},
2/.style={yellow!90!black},
3/.style={red!80!black},
default style/.style={black}
}
As a final example, let us create a style sheet that changes the dashing pattern according to the value
of the attribute. We do not need to define an large number of styles in this case, but can use the default
style key to “calculate” the correct dashing.
2
1
0
1
2
\pgfdvdeclarestylesheet{my dashings}{
default style/.style={dash pattern={on #1pt off 1pt}}
}
\tikz \datavisualization [
school book axes,
visualize as line=normal,
visualize as line=heated,
visualize as line=critical,
style sheet=my dashings]
data group {lines};
836
79.4.3
Creating a New Color Style Sheet
Creating a style sheet that varies colors according to an attribute works the same way as creating a normal
style sheet: Subkeys lies 1, 2, and so on use the style attribute to setup a color. However, instead of using
the color attribute to set the color, you should use the visualizer color key to set the color:
/tikz/visualizer color=hcolor i
(no default)
This key is used to set the color visualizer color to hcolor i. This color is used by visualizers to color
the data they visualize, rather than the current “standard color.” The reason for not using the normal
current color is simply that it makes many internals of the data visualization engine a bit simpler.
2
1
0
1
2
\pgfdvdeclarestylesheet{my colors}
{
default style/.style={visualizer color=black},
1/.style={visualizer color=black},
2/.style={visualizer color=red!80!black},
3/.style={visualizer color=blue!80!black},
}
\tikz \datavisualization [
school book axes,
visualize as line=normal,
visualize as line=heated,
visualize as line=critical,
style sheet=my colors]
data group {lines};
There is an additional command that makes it easy to define a style sheet based on a color series. Color
series are a concept from the xcolor package: The idea is that we start with a certain color for the first
data set and then add a certain “color offset” for each next data point. Please consult the documentation of
the xcolor package for details.
\tikzdvdeclarestylesheetcolorseries{hnamei}{hcolor model i}{hinitial color i}{hstepi}
This command creates a new style sheet using \pgfdvdeclarestylesheet. This style sheet will only
have a default style setup that maps numbers to the color in the color series starting with hinitial color i
and having a stepping of hstepi. Note that when the value of the attribute is 1, which it is the first
data set, the second color in the color series is used (since counting starts at 0 for color series). Thus,
in general, you need to start the hinitial color i “one early.”
2
1
0
79.5
1
2
\tikzdvdeclarestylesheetcolorseries{greens}{hsb}{0.3,1.3,0.8}{0,-.4,-.1}
\tikz \datavisualization [
school book axes,
visualize as line=normal,
visualize as line=heated,
visualize as line=critical,
style sheet=greens]
data group {lines};
Reference: Style Sheets for Lines
The following style sheets can be applied to visualizations that use the visualize as line and related
keys. For the examples, the following style and data set are used:
837
\tikzdatavisualizationset {
example visualization/.style={
scientific axes=clean,
y axis={ticks={style={
/pgf/number format/fixed,
/pgf/number format/fixed zerofill,
/pgf/number format/precision=2}}},
x axis={ticks={tick suffix=${}^\circ$}},
1={label in legend={text=$\frac{1}{6}\sin 11x$}},
2={label in legend={text=$\frac{1}{7}\sin 12x$}},
3={label in legend={text=$\frac{1}{8}\sin 13x$}},
4={label in legend={text=$\frac{1}{9}\sin 14x$}},
5={label in legend={text=$\frac{1}{10}\sin 15x$}},
6={label in legend={text=$\frac{1}{11}\sin 16x$}},
7={label in legend={text=$\frac{1}{12}\sin 17x$}},
8={label in legend={text=$\frac{1}{13}\sin 18x$}}
}
}
\tikz \datavisualization data group {sin functions} = {
data [format=function] {
var set : {1,...,8};
var x : interval [0:50];
func y = sin(\value x * (\value{set}+10))/(\value{set}+5);
}
};
Style sheet vary thickness
This style varies the thickness of lines. It should be used only when there are only two or three lines,
and even then it is not particularly pleasing visually.
0.15
0.10
0.05
0.00
−0.05
−0.10
−0.15
0◦
10◦
20◦
30◦
40◦
50◦
1
sin 11x
6
1
sin 12x
7
1
sin 13x
8
1
sin 14x
9
1
sin 15x
10
1
sin 16x
11
1
sin 17x
12
1
sin 18x
13
\tikz \datavisualization [
visualize as smooth line/.list=
{1,2,3,4,5,6,7,8},
example visualization,
style sheet=vary thickness]
data group {sin functions};
Style sheet vary dashing
This style varies the dashing of lines. Although it is not particularly pleasing visually and although
visualizations using this style sheet tend to look “excited” (but not necessarily “exciting”), this style
sheet is often the best choice when the visualization is to be printed in black and white.
0.15
0.10
0.05
0.00
−0.05
−0.10
−0.15
0◦
10◦
20◦
30◦
40◦
50◦
1
sin 11x
6
1
sin 12x
7
1
sin 13x
8
1
sin 14x
9
1
sin 15x
10
1
sin 16x
11
1
sin 17x
12
1
sin 18x
13
\tikz \datavisualization [
visualize as smooth line/.list=
{1,2,3,4,5,6,7,8},
example visualization,
style sheet=vary dashing]
data group {sin functions};
As can be seen, there are only seven distinct dashing patterns. The eighth and further lines will use
a solid line once more. You will then have to specify the dashing “by hand” using the style option
together with the visualizer.
Style sheet vary dashing and thickness
838
This style alternates between varying the thickness and the dashing of lines. The difference to just
using both the vary thickness and vary dashing is that too thick lines are avoided. Instead, this
style creates clearly distinguishable line styles for many lines (up to 14) with a minimum of visual
clutter. This style is the most useful for visualizations when many different lines (ten or more) should
be printed in black and white.
0.15
1
sin 11x
6
1
sin 12x
7
1
sin 13x
8
1
sin 14x
9
1
sin 15x
10
1
sin 16x
11
1
sin 17x
12
1
sin 18x
13
0.10
0.05
0.00
−0.05
−0.10
−0.15
0◦
10◦
20◦
30◦
40◦
50◦
\tikz \datavisualization [
visualize as smooth line/.list=
{1,2,3,4,5,6,7,8},
example visualization,
style sheet=vary thickness
and dashing]
data group {sin functions};
For comparison, here is the must-less-than-satisfactory result of combining the two independent style
sheets:
0.15
1
sin 11x
6
1
sin 12x
7
1
sin 13x
8
1
sin 14x
9
1
sin 15x
10
1
sin 16x
11
1
sin 17x
12
1
sin 18x
13
0.10
0.05
0.00
−0.05
−0.10
−0.15
0◦
79.6
10◦
20◦
30◦
40◦
50◦
\tikz \datavisualization [
visualize as smooth line/.list=
{1,2,3,4,5,6,7,8},
example visualization,
style sheet=vary thickness,
style sheet=vary dashing]
data group {sin functions};
Reference: Style Sheets for Scatter Plots
The following style sheets can be used both for scatter plots and also with lines. In the latter case, the marks
are added to the lines.
Style sheet cross marks
This style uses different crosses to distinguish between the data points of different data sets. The crosses
were chosen in such a way that when two different cross marks lie at the same coordinate, their overall
shape allows one to still uniquely determine which marks are on top of each other.
This style supports only up to six different data sets.
0.15
0.10
0.05
0.00
−0.05
−0.10
−0.15
0◦
10◦
20◦
30◦
40◦
50◦
1
sin 11x
6
1
sin 12x
7
1
sin 13x
8
1
sin 14x
9
1
sin 15x
10
1
sin 16x
11
1
sin 17x
12
1
sin 18x
13
839
\tikz \datavisualization [
visualize as scatter/.list=
{1,2,3,4,5,6,7,8},
example visualization,
style sheet=cross marks]
data group {sin functions};
0.15
1
sin 11x
6
1
sin 12x
7
1
sin 13x
8
1
sin 14x
9
1
sin 15x
10
1
sin 16x
11
1
sin 17x
12
1
sin 18x
13
0.10
0.05
0.00
−0.05
−0.10
−0.15
0◦
79.7
10◦
20◦
30◦
40◦
50◦
\tikz \datavisualization [
visualize as smooth line/.list=
{1,2,3,4,5,6,7,8},
example visualization,
style sheet=cross marks]
data group {sin functions};
Reference: Color Style Sheets
Color style sheets are very useful for creating visually pleasing data visualizations that contain multiple data
sets. However, there are two things to keep in mind:
• At some point, every data visualization is printed or photo copied in black and white by someone. In
this case, data sets can often no longer be distinguished.
• A few people are color blind. They will not be able to distinguish between red and green lines (and
some people are not even able to distinguish colors at all).
For these reasons, if there is any chance that the data visualization will be printed in black and white
at some point, consider combining color style sheets with style sheets like vary dashing to make data sets
distinguishable in all situations.
Style sheet strong colors
This style sheets uses pure primary colors that can very easily be distinguished. Although not as visually
pleasing as the vary hue style sheet, the visualizations are easier to read when this style sheet is used.
Up to six different data sets are supported.
0.15
50◦
1
sin 11x
6
1
sin 12x
7
1
sin 13x
8
1
sin 14x
9
1
sin 15x
10
1
sin 16x
11
1
sin 17x
12
1
sin 18x
13
50◦
1
sin 11x
6
1
sin 12x
7
1
sin 13x
8
1
sin 14x
9
1
sin 15x
10
1
sin 16x
11
1
sin 17x
12
1
sin 18x
13
0.10
0.05
0.00
−0.05
−0.10
−0.15
0◦
10◦
20◦
30◦
40◦
0.15
0.10
0.05
0.00
−0.05
−0.10
−0.15
0◦
10◦
20◦
30◦
40◦
\tikz \datavisualization [
visualize as smooth line/.list=
{1,2,3,4,5,6,7,8},
example visualization,
style sheet=strong colors]
data group {sin functions};
\tikz \datavisualization [
visualize as smooth line/.list=
{1,2,3,4,5,6,7,8},
example visualization,
style sheet=strong colors,
style sheet=vary dashing]
data group {sin functions};
Unlike strong colors, the following style sheets support, in principle, an unlimited number of data set.
In practice, as always, more than four or five data sets lead to nearly indistinguishable data sets.
Style sheet vary hue
This style uses a different hue for each data set.
840
0.15
0.10
0.05
0.00
−0.05
−0.10
−0.15
0◦
10◦
20◦
30◦
40◦
50◦
1
sin 11x
6
1
sin 12x
7
1
sin 13x
8
1
sin 14x
9
1
sin 15x
10
1
sin 16x
11
1
sin 17x
12
1
sin 18x
13
\tikz \datavisualization [
visualize as smooth line/.list=
{1,2,3,4,5,6,7,8},
example visualization,
style sheet=vary hue]
data group {sin functions};
Style sheet shades of blue
As the name suggests, different shades of blue are used for different data sets.
0.15
50◦
1
sin 11x
6
1
sin 12x
7
1
sin 13x
8
1
sin 14x
9
1
sin 15x
10
1
sin 16x
11
1
sin 17x
12
1
sin 18x
13
50◦
1
sin 11x
6
1
sin 12x
7
1
sin 13x
8
1
sin 14x
9
1
sin 15x
10
1
sin 16x
11
1
sin 17x
12
1
sin 18x
13
0.10
0.05
0.00
−0.05
−0.10
−0.15
0◦
10◦
20◦
30◦
40◦
\tikz \datavisualization [
visualize as smooth line/.list=
{1,2,3,4,5,6,7,8},
example visualization,
style sheet=shades of blue]
data group {sin functions};
Style sheet shades of red
0.15
0.10
0.05
0.00
−0.05
−0.10
−0.15
0◦
10◦
20◦
30◦
40◦
\tikz \datavisualization [
visualize as smooth line/.list=
{1,2,3,4,5,6,7,8},
example visualization,
style sheet=shades of red]
data group {sin functions};
Style sheet gray scale
For once, this style sheet can also be used when the visualization is printed in black and white.
0.15
0.10
0.05
0.00
−0.05
−0.10
−0.15
0◦
79.8
10◦
20◦
30◦
40◦
50◦
1
sin 11x
6
1
sin 12x
7
1
sin 13x
8
1
sin 14x
9
1
sin 15x
10
1
sin 16x
11
1
sin 17x
12
1
sin 18x
13
\tikz \datavisualization [
visualize as smooth line/.list=
{1,2,3,4,5,6,7,8},
example visualization,
style sheet=gray scale]
data group {sin functions};
Usage: Labeling Data Sets Inside the Visualization
In a visualization that contains multiple data sets, it is often necessary to clearly point out which line or
mark type corresponds to which data set. This can be done in the main text via a sentence like “the normal
data (black) lies clearly below the critical values (red),” but it often a good idea to indicate data sets ideally
directly inside the data visualization or directly next to it in a so-called legend.
841
The data visualization engine has direct support both for indicating data sets directly inside the visualization and also for indicating them in a legend.
The “best” way of indicating where a data set lies or which color is used for it is to put a label directly
inside the data visualization. The reason this is the “best” way is that people do not have to match the
legend entries against the data, let alone having to look up the meaning of line styles somewhere in the text.
However, adding a label directly inside the visualization is also the most tricky way of indicating data sets
since it is hard to compute good positions for the labels automatically and since there needs to be some
empty space where the label can be put.
79.8.1
Placing a Label Next to a Data Set
The following key is used to create a label inside the data visualization for a data set:
/tikz/data visualization/visualizer options/label in data=hoptionsi
(no default)
This key is passed to a visualizer that has previously been created using keys starting visualize as
.... It will create a label inside the data visualization “next” to the visualizer (the details are explained
in a moment). You can use this key multiple times with a visualizer to create multiple labels at different
points with different texts.
The hoptionsi determine which text is shown and where it is shown. They are executed with the
following path prefix:
/tikz/data visualization/visualizer label options
In order to configure which text is shown and where, use the following keys inside the hoptionsi:
/tikz/data visualization/visualizer label options/text=htexti
(no default)
This is the text that will be displayed next to the data. It will be to the “left” of the data, see the
description below.
/tikz/data visualization/visualizer label options/text’=htexti
(no default)
Like text, only the text will be to the “right” of the data.
The following keys are used to configure where the label will be shown. They use different strategies
to specify one data point where the label will be anchored. The coordinate of this data point will be
stored in (label visualizer coordinate). Independently of the strategy, once the data point has been
chosen, the coordinate of the next data point is stored in (label visualizer coordinate’). Then, a
(conceptual) line is created from the first coordinate to the second and a node is placed at the beginning
of this line to its “left” or, for the text’ option, on its “right.” More precisely, an automatic anchor is
computed for a node placed implicitly on this line using the auto option or, for the text’ option, using
auto,swap.
The node placed at the position computed in this way will have the htexti set by the text or text’
option and its styling is determined by the current node style.
Let us now have a look at the different ways of determining the data point at which the label in anchored:
/tikz/data visualization/visualizer label options/when=hattributeiishnumber i
(no default)
This key causes the value of the hattributei to be monitored in the stream of data points. The
chosen is data point is the first data point where the hattributei is at least hnumber i (if this never
happens, the last data point is used).
842
2
x2
x/2
1
2
1
ex
−2
−1
x
0
−1
\tikz \datavisualization [
school book axes,
x axis={label=$x$},
visualize as smooth line/.list={log, lin, squared, exp},
log=
{label in data={text’=$\log x$, when=y is -1,
text colored}},
lin=
{label in data={text=$x/2$,
when=x is 2}},
squared={label in data={text=$x^2$,
when=x is 1.1}},
exp=
{label in data={text=$e^x$,
when=x is -2,
text colored}},
style sheet=vary hue]
data group {function classes};
log x
/tikz/data visualization/visualizer label options/index=hnumber i
(no default)
This key chooses the hnumber ith data point belonging to the visualizer’s data set.
2
20
1
5
−2
10
−1
x
0
1
2
\tikz \datavisualization [
school book axes,
x axis={label=$x$},
visualize as smooth line/.list={exp},
exp=
{label in data={text=$5$, index=5},
label in data={text=$10$, index=10},
label in data={text=$20$, index=20},
style={mark=x}},
style sheet=vary hue]
data group {function classes};
−1
/tikz/data visualization/visualizer label options/pos=hfractioni
(no default)
This key chooses the first data point belonging to the data set whose index is at least hfractioni
times the number of all data points in the data set.
.95
2
1
.5
.2
−2
−1
0
x
1
2
\tikz \datavisualization [
school book axes,
x axis={label=$x$},
visualize as smooth line=exp,
exp=
{label in data={text=$.2$, pos=0.2},
label in data={text=$.5$, pos=0.5},
label in data={text=$.95$, pos=0.95},
style={mark=x}},
style sheet=vary hue]
data group {function classes};
−1
/tikz/data visualization/visualizer label options/auto
(no value)
This key is executed automatically by default. It works like the pos option, where the hfractioni is
set to (hdata set’s index i − 1/2)/hnumber of data setsi. For instance, when there are 10 data sets,
the fraction for the first one will be 5%, the fraction for the second will be 15%, for the third it will
be 25%, ending with 95% for the last one.
The net effect of all this is that when there are several lines, labels will be placed at different
positions along the lines with hopefully only little overlap.
843
3
2.5
x3
2
1.5
1
x2
2x
0.5
0
0
0.25
0.5
0.75
1
1.25
1.5
\tikz \datavisualization [
scientific axes=clean,
visualize as smooth line/.list={linear, squared, cubed},
linear ={label in data={text=$2x$}},
squared={label in data={text=$x^2$}},
cubed ={label in data={text=$x^3$}}]
data [set=linear, format=function] {
var x : interval [0:1.5];
func y = 2*\value x;
}
data [set=squared, format=function] {
var x : interval [0:1.5];
func y = \value x * \value x;
}
data [set=cubed, format=function] {
var x : interval [0:1.5];
func y = \value x * \value x * \value x;
};
As can be seen in the example, the result is not always satisfactory. In this case, the pin in data
option might be preferable, see below.
The following keys allow you to style labels.
/tikz/data visualization/visualizer label options/node style=hoptionsi
Just passes the options to /tikz/data visualization/node style.
/tikz/data visualization/visualizer label options/text colored
(no default)
(no value)
Causes the node style to set the text color to visualizer color. The effect of this is that the
label’s text will have the same color as the data set to which it is attached.
/tikz/data visualization/every data set label
(style, no value)
This style is executed with every label that represents a data set. Inside this style, use node style
to change the appearance of nodes. This style has a default definition, usually you should just
append things to this style.
2
x2
1
x/2
ex
−2
−1
0
−1
x
1
log x
2
\tikz \datavisualization [
school book axes,
x axis={label=$x$},
visualize as smooth line/.list={log, lin, squared, exp},
every data set label/.append style={text colored},
log=
{label in data={text’=$\log x$, when=y is -1}},
lin=
{label in data={text=$x/2$,
node style=sloped,
when=x is 2}},
squared={label in data={text=$x^2$,
when=x is 1.1}},
exp=
{label in data={text=$e^x$,
node style=sloped,
when=x is -2}},
style sheet=vary hue]
data group {function classes};
/tikz/data visualization/every label in data
(style, no value)
Like every data set label, this key is also executed with labels. However, this key is executed
after the style sheets have been executed, giving you a chance to overrule their styling.
79.8.2
Connecting a Label to a Data Set via a Pin
/tikz/data visualization/visualizer options/pin in data=hoptionsi
(no default)
This key is a variant of the label in data key and takes the same options, plus two additional ones.
The difference to label in data is that the label node is shown a bit removed from the data set, but
connected to it via a small line (this is like the difference between the label and pin options).
844
3
x3
2.5
2
1.5
1
x2
2x
0.5
0
0
0.25
0.5
0.75
1
1.25
1.5
\tikz \datavisualization [
scientific axes=clean,
visualize as smooth line/.list={linear, squared, cubed},
linear ={pin in data={text=$2x$}},
squared={pin in data={text=$x^2$}},
cubed ={pin in data={text=$x^3$}}]
data [set=linear, format=function] {
var x : interval [0:1.5];
func y = \value x;
}
data [set=squared, format=function] {
var x : interval [0:1.5];
func y = \value x * \value x;
}
data [set=cubed, format=function] {
var x : interval [0:1.5];
func y = \value x * \value x * \value x;
};
The following keys can be used additionally:
/tikz/data visualization/visualizer label options/pin angle=hanglei
(no default)
The position of the label of a pin in data is mainly computed in the same way as for a label in
data. However, once the position has been computed, the label is shifted as follows:
• When an hanglei is specified using the present key, the shift is by the current value of pin
length in the direction of hanglei.
• When hanglei is empty (which is the default), then the shift is also by the current value of
pin length, but now in the direction that is orthogonal and to the left of the line between the
coordinate of the data point and the coordinate of the next data point. When text’ is used,
the direction is to the right instead of the left.
/tikz/data visualization/visualizer label options/pin length=hdimensioni
See the description of pin angle.
2
x/2
1
x2
x
e
−2
−1
0
x
1
−1
log x
79.9
2
(no default)
\tikz \datavisualization [
school book axes,
x axis={label=$x$},
visualize as smooth line/.list={log, lin, squared, exp},
every data set label/.append style={text colored},
log=
{pin in data={text’=$\log x$, when=y is -1}},
lin=
{pin in data={text=$x/2$, when=x is 2,
pin length=1ex}},
squared={pin in data={text=$x^2$, when=x is 1.1,
pin angle=230}},
exp=
{label in data={text=$e^x$, when=x is -2}},
style sheet=vary hue]
data group {function classes};
Usage: Labeling Data Sets Inside a Legend
The “classical” way of indicating the style used for the different data sets inside a visualization is a legend. It
is a description next to or even inside the visualization that contains one line for each data set and displays
an iconographic version of the data set next to some text labeling the data set. Note, however, that even
though legend are quite common, also consider using a label in data or a pin in data instead.
Creating a high-quality legend is by no means simple. A legend should not distract the reader, so
aggressive borders should definitively be avoided. A legend should make it easy to match the actual styling
of a data set (like, say, using a red, dashed line) to the “iconographic” representation of this styling. An
example of what can go wrong here is using short lines to represent lines dashed in different way where
the lines are so short that the differences in the dashing cannot be discerned. Another example is showing
straight lines with plot marks on them where the plot marks are obscured by the horizontal line itself, while
the plot marks are clearly visible in the actual visualization since no horizontal lines occur.
The data visualization engine comes with a large set of options for creating and placing high-quality
legends next or inside data visualizations.
845
79.9.1
Creating Legends and Legend Entries
A data visualization can be accompanied by one or more legends. In order to create a legend, the following
key can be used (although, in practice, you will usually use the legend key instead, see below):
/tikz/data visualization/new legend=hlegend namei
(default main legend)
This key is used to create a new legend named hlegend namei. The legend is empty by default and
further options are needed to add entries to it. When the key is called a second time for the same
hlegend namei nothing happens.
When a legend is created, a new key is created that can subsequently be used to configure the legend:
/tikz/data visualization/hlegend name i=hoptionsi
(no default)
When this key is used, the hoptionsi are executed with the path prefix
/tikz/data visualization/legend options
The different keys with this path prefix allow you to change the position where the legend is shown
and how it is organised (for instance, whether legend entries are shown in a row or in a column or
in a square).
The different possible keys will be explained in the course of this section.
In the end, the legend is just a Tik Z node, a matrix node, to be precise. The following key is used to
style this node:
/tikz/data visualization/legend options/matrix node style=hoptionsi
(no default)
Adds the hoptionsi to the list of options that will be executed when the legend’s node is created.
2
log x
x/2
x2
ex
1
0
−1
−2
−1
0
1
2
\tikz \datavisualization [
scientific axes,
visualize as smooth line/.list=
{log, lin, squared, exp},
legend={matrix node style={fill=black!25}},
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
squared={label in legend={text=$x^2$}},
exp=
{label in legend={text=$e^x$}},
style sheet=vary dashing]
data group {function classes};
The following style allows you to configure the default appearance of every newly created legend:
/tikz/data visualization/legend options/every new legend
(style, no value)
This key defaults to east outside, label style=text right. This means that by default a
legend is placed to the right of the data visualization and that in the individual legend entries the
text is to the right of the data set visualization.
log x
x/2
2
1
0
−1
−2
−1
0
1
2
\tikz \datavisualization [
scientific axes, x axis={label=$x$},
visualize as smooth line/.list={log, lin, squared, exp},
new legend={upper legend},
new legend={lower legend},
upper legend=above,
lower legend=below,
log=
{label in legend={text=$\log x$, legend=upper legend}},
lin=
{label in legend={text=$x/2$, legend=upper legend}},
squared={label in legend={text=$x^2$, legend=lower legend}},
exp=
{label in legend={text=$e^x$, legend=lower legend}},
style sheet=vary dashing]
data group {function classes};
x
x2
ex
846
(no default)
/tikz/data visualization/legend=hoptionsi
This is a shorthand for new legend=main legend, main legend=hoptionsi. In other words, this key
creates a new main legend and immediately passes the configuration hoptionsi to this legend.
\tikz \datavisualization [
scientific axes, x axis={label=$x$},
visualize as smooth line/.list={log, lin, squared, exp},
legend=below,
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
squared={label in legend={text=$x^2$}},
exp=
{label in legend={text=$e^x$}},
style sheet=vary dashing]
data group {function classes};
2
1
0
−1
−2
−1
0
1
2
x
log x
x2
x/2
ex
As pointed out above, a legend is empty by default. In particular, the different data sets are not
automatically inserted into the legend. Instead, the key label in legend must be used together with a
data set:
(no default)
/tikz/data visualization/visualizer options/label in legend=hoptionsi
This key is passed to a data set, similar to options like pin in data or smooth line. The hoptionsi
are used to configure the following:
• The legend in which the data set should be visualized.
• The text that is to be shown in the legend for the data set.
• The appearance of the legend entries.
In detail, the hoptionsi are executed with the path prefix
/tikz/data visualization/legend entry options
To configure in which legend the label should appear, use the following key:
/tikz/data visualization/legend entry options/legend=hnamei
legend)
(no default, initially main
Set this key to the name of a legend that has previously been created using new legend. The label
will then be shown in this legend.
In most cases, there is only one legend (namely main legend) and there is no need to set this key
since it defaults to the main legend.
Also note that the legend hnamei is automatically created if it nodes not yet exist.
/tikz/data visualization/legend entry options/text=htexti
(no default)
Use this key to setup the htexti that is shown as the label of the data set.
x2
2
ex
1
log x
x/2
0
−1
−2
−1
0
1
\tikz \datavisualization [
scientific axes, x axis={label=$x$},
visualize as smooth line/.list=
{log, lin, squared, exp},
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
squared={pin in data
={text=$x^2$, pos=0.1}},
exp=
{label in data ={text=$e^x$}},
style sheet=vary dashing]
data group {function classes};
2
x
In addition to the two keys described above, there are further keys that are described in Section 79.9.6.
847
79.9.2
Rows and Columns of Legend Entries
In a legend, the different legend entries are arranged in a matrix, which typically has only one row or one
column. For the impatient reader: Say rows=1 to get everything in a row, say columns=1 to get everything
in a single column, and skip the rest of this section.
The more patient reader will appreciate that when there are very many different data sets in a single
visualization, it may be necessary to use more than one row or column inside the legend. Tik Z comes with
a rather powerful mechanism for distributing the multiple legend entries over the matrix.
The first thing to decide is in which “direction” the entries should be inserted into the matrix. Suppose
we have a 3 × 3 matrix and our entries are a, b, c, and so on. Then, one might place the a in the upper left
corner of the matrix, b in the upper middle position, c in the upper right position, and d in the middle left
position. This is a “first right, then down” strategy. A different strategy might be to place the a in the upper
left corner, but b in the middle left position, c in the lower left position, and d then in the upper middle
position. This is a “first down, then right” strategy. In certain situations it might even make sense to place
a in the lower right corner and then go “first up, then left”.
All of these strategies are supported by the legend command. You can configure which strategy is used
using the following keys:
/tikz/data visualization/legend options/down then right
(no value)
Causes the legend entries to fill the legend matrix first downward and, once a column is full, the next
column is begun to the right of the previous one. This is the default.
1
2
3
4
5
6
7
8
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={down then right, columns=3}]
data group {sin functions};
In the example, the legend example is the following style:
\tikzdatavisualizationset {
legend example/.style={
scientific axes, all axes={length=1cm, ticks=none},
1={label in legend={text=1}},
2={label in legend={text=2}},
3={label in legend={text=3}},
4={label in legend={text=4}},
5={label in legend={text=5}},
6={label in legend={text=6}},
7={label in legend={text=7}},
8={label in legend={text=8}}
}
}
/tikz/data visualization/legend options/down then left
7
8
4
5
6
1
2
3
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={down then left, columns=3}]
data group {sin functions};
/tikz/data visualization/legend options/up then right
3
2
1
6
5
4
8
7
8
7
3
2
1
(no value)
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={up then right, columns=3}]
data group {sin functions};
/tikz/data visualization/legend options/up then left
6
5
4
(no value)
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={up then left, columns=3}]
data group {sin functions};
848
(no value)
(no value)
/tikz/data visualization/legend options/left then up
8
5
2
6
3
7
4
1
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={left then up, columns=3}]
data group {sin functions};
(no value)
/tikz/data visualization/legend options/left then down
3
6
2
5
8
1
4
7
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={left then down, columns=3}]
data group {sin functions};
(no value)
/tikz/data visualization/legend options/right then up
7
4
1
8
5
2
6
3
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={right then up, columns=3}]
data group {sin functions};
(no value)
/tikz/data visualization/legend options/right then down
1
4
7
2
5
8
3
6
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={right then down, columns=3}]
data group {sin functions};
Having configured the directions in which the matrix is being filled, you must next setup the number of
rows or columns that are to be shown. There are actually two different ways of doing so. The first way is
to specify a maximum number of rows or columns. For instance, you might specify that there should be at
most ten rows to a column and when there are more, a new column should be begun. This is achieved using
the following keys:
/tikz/data visualization/legend options/max rows=hnumber i
(no default)
As the legend matrix is being filled, whenever the number of rows in the current column would exceed
hnumber i, a new column is started.
1
2
3
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={max rows=3}]
data group {sin functions};
4
5
6
7
8
1
2
3
4
5
6
7
8
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={max rows=4}]
data group {sin functions};
1
2
3
4
5
6
7
8
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={max rows=5}]
data group {sin functions};
849
/tikz/data visualization/legend options/max columns=hnumber i
(no default)
This key works like max rows, only now the number of columns is monitored. Note that this strategy
only really makes sense when the when you use this key with a strategy that first goes left or right and
then up or down.
1
5
1
3
5
7
2
4
6
8
1
4
7
2
5
8
3
6
2
6
3
7
4
8
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={right then down, max columns=2}]
data group {sin functions};
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={right then down,max columns=3}]
data group {sin functions};
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={right then down,max columns=4}]
data group {sin functions};
The second way of specifying the number of entries in a row or column is to specify an “ideal number
of rows or columns.” The idea is as follows: Suppose that we use the standard strategy and would like to
have everything in two columns. Then if there are eight entries, the first four should go to the first column,
while the next four should go to the second column. If we have 20 entries, the first ten should go the first
column and the next ten to the second, and so on. So, in general, the objective is to distribute the entries
evenly so the this “ideal number of columns” is reached. Only when there are too few entries to achieve this
or when the number of entries per column would exceed the max rows value, will the number of columns
deviate from this ideal value.
/tikz/data visualization/legend options/ideal number of columns=hnumber i
(no default)
Specifies, that the entries should be split into hnumber i different columns, whenever possible. However,
when there would be more than the max rows value of rows per column, more columns than the ideal
number are created.
1
2
1
2
3
4
5
6
7
8
3
4
5
6
7
8
1
2
3
4
5
6
7
8
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={ideal number of columns=2}]
data group {sin functions};
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={ideal number of columns=4}]
data group {sin functions};
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={max rows=3,ideal number of columns=2}]
data group {sin functions};
/tikz/data visualization/legend options/rows=hnumber i
Shorthand for ideal number of rows=hnumber i.
850
(no default)
/tikz/data visualization/legend options/ideal number of rows=hnumber i
(no default)
Works like ideal number of columns.
1
2
3
4
1
2
3
5
6
7
8
1
2
3
4
5
6
7
8
4
5
6
7
8
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={ideal number of rows=2}]
data group {sin functions};
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={ideal number of rows=4}]
data group {sin functions};
\tikz \datavisualization [
visualize as smooth line/.list={1,2,3,4,5,6,7,8},
legend example, style sheet=vary hue,
main legend={max columns=3,ideal number of rows=2}]
data group {sin functions};
/tikz/data visualization/legend options/columns=hnumber i
(no default)
Shorthand for ideal number of columns=hnumber i.
79.9.3
Legend Placement: The General Mechanism
A legend can either be placed next to the data visualization or inside the data visualization at some place
where there are no data entries. Both approached have advantages: Placing the legend next to the visualization minimises the “cluttering” by keeping all the extra information apart from the actual data, while
placing the legend inside the visualization minimises the distance between the data sets and their explanations, making it easier for the eye to connect them.
For both approaches there are options that make the placement easier, see Sections 79.9.4 and 79.9.5,
but these options internally just map to the following two options:
/tikz/data visualization/legend options/anchor=hanchor i
(no default)
The whole legend is a Tik Z-matrix internally. Thus, in particular, it is stored in a node, which has
anchors. Like for any other node, when the node is shown, the node is shifted in such a way that the
hanchor i of the node lies at the current at position.
/tikz/data visualization/legend options/at=hcoordinatei
(no default)
Configures the hcoordinatei at which the hanchor i of the legend’s node should lie.
It may seem hard to predict a good hcoordinatei for a legend since, depending of the size of the axis,
different positions need to the chosen for the legend. However, it turns out that one can often use
the coordinates of the special nodes data bounding box and data visualization bounding box,
documented in Section 75.6.
As an example, let us put a legend to the right of the visualization, but so that the first entry starts at
the top of the visualization:
log x
x/2
x2
ex
2
1
0
−1
−2
−1
0
x
1
2
\tikz \datavisualization [
scientific axes, x axis={label=$x$},
visualize as smooth line/.list=
{log, lin, squared, exp},
legend={anchor=north west, at=
(data visualization bounding box.north east)},
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
squared={label in legend={text=$x^2$}},
exp=
{label in legend={text=$e^x$}},
style sheet=vary dashing]
data group {function classes};
As can be seen, a bit of an additional shift might have been in order, but the result is otherwise quite
satisfactory.
851
79.9.4
Legend Placement: Outside to the Data Visualization
The following keys make it easy to place a legend outside the data visualization.
/tikz/data visualization/legend options/east outside
(no value)
Placing the legend to the right of the data visualization is the default:
2
log x
x/2
x2
ex
1
0
−1
−2
−1
0
1
2
\tikz \datavisualization [
scientific axes,
visualize as smooth line/.list=
{log, lin, squared, exp},
legend=east outside,
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
squared={label in legend={text=$x^2$}},
exp=
{label in legend={text=$e^x$}},
style sheet=strong colors]
data group {function classes};
/tikz/data visualization/legend options/right
(no value)
This is an easier-to-remember alias.
/tikz/data visualization/legend options/north east outside
(no value)
A variant, where the legend is to the right, but aligned with the northern end of the data visualization:
log x
x/2
x2
ex
2
1
0
−1
−2
−1
0
1
2
\tikz \datavisualization [
scientific axes,
visualize as smooth line/.list=
{log, lin, squared, exp},
legend=north east outside,
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
squared={label in legend={text=$x^2$}},
exp=
{label in legend={text=$e^x$}},
style sheet=strong colors]
data group {function classes};
/tikz/data visualization/legend options/south east outside
2
1
log x
x/2
x2
ex
0
−1
−2
−1
0
1
2
\tikz \datavisualization [
scientific axes,
visualize as smooth line/.list=
{log, lin, squared, exp},
legend=south east outside,
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
squared={label in legend={text=$x^2$}},
exp=
{label in legend={text=$e^x$}},
style sheet=strong colors]
data group {function classes};
/tikz/data visualization/legend options/west outside
The legend is placed left. Note that the text also swaps its position.
2
log x
x/2
x2
ex
1
0
−1
−2
−1
0
1
2
(no value)
\tikz \datavisualization [
scientific axes,
visualize as smooth line/.list=
{log, lin, squared, exp},
legend=west outside,
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
squared={label in legend={text=$x^2$}},
exp=
{label in legend={text=$e^x$}},
style sheet=strong colors]
data group {function classes};
852
(no value)
/tikz/data visualization/legend options/left
(no value)
This is an easier-to-remember alias.
/tikz/data visualization/legend options/north west outside
log x
x/2
x2
ex
\tikz \datavisualization [
scientific axes,
visualize as smooth line/.list=
{log, lin, squared, exp},
legend=north west outside,
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
squared={label in legend={text=$x^2$}},
exp=
{label in legend={text=$e^x$}},
style sheet=strong colors]
data group {function classes};
2
1
0
−1
−2
−1
0
1
2
/tikz/data visualization/legend options/south west outside
1
0
−1
−2
−1
0
1
(no value)
\tikz \datavisualization [
scientific axes,
visualize as smooth line/.list=
{log, lin, squared, exp},
legend=south west outside,
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
squared={label in legend={text=$x^2$}},
exp=
{label in legend={text=$e^x$}},
style sheet=strong colors]
data group {function classes};
2
log x
x/2
x2
ex
(no value)
2
/tikz/data visualization/legend options/north outside
(no value)
The legend is placed above the data. Note that the legend entries now for a row rather than a column.
log x
x2
x/2
ex
2
1
0
−1
−2
−1
0
1
\tikz \datavisualization [
scientific axes,
visualize as smooth line/.list=
{log, lin, squared, exp},
legend=north outside,
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
squared={label in legend={text=$x^2$}},
exp=
{label in legend={text=$e^x$}},
style sheet=strong colors]
data group {function classes};
2
/tikz/data visualization/legend options/above
(no value)
This is an easier-to-remember alias.
/tikz/data visualization/legend options/south outside
\tikz \datavisualization [
scientific axes,
visualize as smooth line/.list=
{log, lin, squared, exp},
legend=south outside,
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
squared={label in legend={text=$x^2$}},
exp=
{label in legend={text=$e^x$}},
style sheet=strong colors]
data group {function classes};
2
1
0
−1
−2
log x
−1
0
x/2
1
x2
2
ex
853
(no value)
(no value)
/tikz/data visualization/legend options/below
This is an easier-to-remember alias.
79.9.5
Legend Placement: Inside to the Data Visualization
There are two sets of options for placing a legend directly inside a data visualization: First, there are options
for placing it inside, but next to some part of the border. Second, there are options for positioning it relative
to a coordinate given by a certain data point.
(no value)
/tikz/data visualization/legend options/south east inside
Puts the legend in the upper right corner of the data.
2
1
0
log x
x/2
−1
−2
−1
0
1
\tikz \datavisualization [
scientific axes,
visualize as smooth line/.list=
{log, lin},
legend=south east inside,
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
style sheet=strong colors]
data group {function classes};
2
Note that the text is now a little smaller since there tends to be much less space inside the data
visualization than next to it. Also, the legend’s node is filled in white by default to ensures that the
legend is clearly legible even in the presence of, say, a grid or data points behind it. This behaviour is
triggered by the following style key:
/tikz/data visualization/legend options/every legend inside
(style, no value)
Executed the keys opaque by default and sets the text size to the size of footnotes.
In order to further configure the default appearance of an inner legend, the following keys might be useful:
/tikz/data visualization/legend options/opaque=hcolor i
(default white)
When this key is used, the legend’s node will be filled with the hcolor i and its corners will be rounded.
Additionally, the inner and outer separations will be set to sensible values.
/tikz/data visualization/legend options/transparent
(no value)
Sets the filling of the legend node to none.
The following keys work much the same way as south east inside:
/tikz/data visualization/legend options/east inside
(no value)
/tikz/data visualization/legend options/north east inside
(no value)
/tikz/data visualization/legend options/south west inside
(no value)
/tikz/data visualization/legend options/west inside
(no value)
/tikz/data visualization/legend options/north west inside
(no value)
The keys south inside and north inside are a bit different: They use a row rather than a column for
the legend entries:
/tikz/data visualization/legend options/south inside
(no value)
Puts the legend in the upper right corner of the data. Note that the text is now a little smaller since
there tends to be much less space inside the data visualization than next to it.
854
\tikz \datavisualization [
scientific axes,
visualize as smooth line/.list={log, lin},
legend=south inside,
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
style sheet=strong colors]
data group {function classes};
2
1
0
−1
log x
−2
−1
0
x/2
1
2
/tikz/data visualization/legend options/north inside
(no value)
As above.
The above keys do not always give you as fine a control as you may need over the placement of the legend.
In such cases, the following keys may help (or you can revert to directly setting the at and the anchor keys):
/tikz/data visualization/legend options/at values=hdata pointi
(no default)
This key allows you to specify the desired center of the legend in terms of a data point. The hdata pointi
should be a list of comma-separated key–value pairs that specify a data point. The legend will then be
centered at this data point.
\tikz \datavisualization [
scientific axes,
visualize as smooth line/.list={log, lin},
legend={at values={x=-1, y=2}},
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
style sheet=strong colors]
data group {function classes};
log x
x/2
2
1
0
−1
−2
−1
0
1
2
/tikz/data visualization/legend options/right of=hdata pointi
(no default)
Works like at values, but the anchor is set to west:
\tikz \datavisualization [
scientific axes,
visualize as smooth line/.list={log, lin},
legend={right of={x=-1, y=2}},
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
style sheet=strong colors]
data group {function classes};
log x
x/2
2
1
0
−1
−2
−1
0
1
2
The following keys work similarly:
/tikz/data visualization/legend options/above right of=hdata pointi
(no default)
/tikz/data visualization/legend options/above of=hdata pointi
(no default)
/tikz/data visualization/legend options/above left of=hdata pointi
(no default)
/tikz/data visualization/legend options/left of=hdata pointi
(no default)
/tikz/data visualization/legend options/below left of=hdata pointi
(no default)
/tikz/data visualization/legend options/below of=hdata pointi
(no default)
/tikz/data visualization/legend options/below right of=hdata pointi
(no default)
855
79.9.6
Legend Entries: General Styling
The entries in a legend can be styled in several ways:
• You can configure the styling of the text node.
• You can configure the relative placement of the text node and the little picture depicting the data set’s
styling.
• You can configure how the data set’s styling is depicted.
Before we have look at how each of these are configured, in detail, let us first have a look at the keys
that allow us to save a set of such styles:
/tikz/data visualization/every label in legend
(style, no value)
This key is executed with every label in a legend. However, the options stored in this style are executed
with the path prefix /tikz/data visualization/legend entry options. Thus, this key can use keys
like node style to configure the styling of all text nodes:
log x
2
x/2
1
x2
ex
0
−1
−2
−1
0
1
2
\tikz \datavisualization [
scientific axes,
every label in legend/.style={node style=
{fill=red!30}},
visualize as smooth line/.list=
{log, lin, squared, exp},
legend=north east outside,
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$,
node style={circle, draw=red}}},
squared={label in legend={text=$x^2$}},
exp=
{label in legend={text=$e^x$}},
style sheet=strong colors]
data group {function classes};
/tikz/data visualization/legend options/label style=hoptionsi
(no default)
This key can be used with a legend. It will simply add the hoptionsi to the every label in legend
style for the given legend.
2
log x
1
x/2
0
x2
ex
−1
−2
79.9.7
−1
0
1
2
\tikz \datavisualization [
scientific axes,
visualize as smooth line/.list=
{log, lin, squared, exp},
legend={label style={node style=draw}},
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$,
node style={circle, draw=red}}},
squared={label in legend={text=$x^2$}},
exp=
{label in legend={text=$e^x$}},
style sheet=strong colors]
data group {function classes};
Legend Entries: Styling the Text Node
The appearance of the text nodes is easy to configure.
/tikz/data visualization/legend entry options/node style=hoptionsi
(no default)
This key adds hoptionsi to the styling of the text nodes of the label.
log x
2
x/2
1
x2
ex
0
−1
−2
−1
0
1
2
\tikz \datavisualization [
scientific axes,
visualize as smooth line/.list=
{log, lin, squared, exp},
legend=north east outside,
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$,
node style={circle, draw=red}}},
squared={label in legend={text=$x^2$}},
exp=
{label in legend={text=$e^x$}},
style sheet=strong colors]
data group {function classes};
856
/tikz/data visualization/legend entry options/text colored
(no value)
Causes the node style to set the text color to visualizer color. The effect of this is that the label’s
text will have the same color as the data set to which it is attached.
2
log x
x/2
x2
ex
1
0
−1
−2
79.9.8
−1
0
1
2
\tikz \datavisualization [
scientific axes,
visualize as smooth line/.list=
{log, lin, squared, exp},
legend={label style=text colored},
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
squared={label in legend={text=$x^2$}},
exp=
{label in legend={text=$e^x$}},
style sheet=strong colors]
data group {function classes};
Legend Entries: Text Placement
Three keys govern where the text will be placed relative to the data set style visualization.
/tikz/data visualization/legend entry options/text right
(no value)
Placed the text node to the right of the data set style visualization. This is the default for most, but
not all, legends.
/tikz/data visualization/legend entry options/text left
(no value)
Placed the text node to the left of the data set style visualization.
\tikz \datavisualization [
scientific axes,
visualize as smooth line/.list=
{log, lin, squared, exp},
legend={label style=text left},
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
squared={label in legend={text=$x^2$}},
exp=
{label in legend={text=$e^x$}},
style sheet=strong colors]
data group {function classes};
2
log x
x/2
x2
ex
1
0
−1
−2
−1
0
1
2
/tikz/data visualization/legend entry options/text only
(no value)
Shows only the text nodes and no data set style visualization at all. This options only makes sense in
conjunction with the text colored options, which is why this options is also selected implicitly.
2
1
0
log x x2
x/2 ex
−1
−2
79.9.9
−1
0
1
2
\tikz \datavisualization [
scientific axes,
visualize as smooth line/.list=
{log, lin, squared, exp},
legend={south east inside, rows=2,
label style=text only},
log=
{label in legend={text=$\log x$}},
lin=
{label in legend={text=$x/2$}},
squared={label in legend={text=$x^2$}},
exp=
{label in legend={text=$e^x$}},
style sheet=strong colors]
data group {function classes};
Advanced: Labels in Legends and Their Visualizers
The following explanations are important only for you if you intend to create a new visualizer and an
accompanying label in legend visualizer; otherwise you can safely proceed with the next section.
A legend entry consists not only of some explaining text, but, even more importantly, of a visual representation of the style used for the data points, created by a label in legend visualizer. For instance, when
data points are visualized as lines in different colors, the legend entry for the first line might consist of the
text “first experiment” and a short line in black and the second entry might consist of “failed experiment”
857
and a short line in red – assuming, of course, that the style sheet makes the first line black and the second
line blue. As another example, when data sets are visualized as clouds of plot marks, the texts in the legend
would be accompanied by the plot marks used to visualize the data sets.
For every visualizer, the label in legend visualizer creates an appropriate visualization of the data set’s
styling. There may be more than one possible such label in legend visualizer that is appropriate, in which
case options are used to choose between them.
Let us start with the key for creating a new legend entry. This key gets called for instance by label in
legend:
/tikz/data visualization/new legend entry=hoptionsi
(no default)
This key will add a new entry to the legend that is identified by the hoptionsi. For this, the hoptionsi
are executed once with the path prefix /tikz/data visualization/legend entry options and the
resulting setting of the legend key is used to pick which legend the new entry should belong to. Then,
the hoptionsi are stored away for the time being.
Later, when the legend is created, the hoptionsi get executed once more. This time, however, the legend
key is no longer important. Instead, the hoptionsi that setup keys like text or visualizer in legend
now play a role.
In detail, the following happens:
• For the legend entry, a little cell picture is created in the matrix of the legend (see Section 20.3 for
details on cell pictures).
• Inside this picture, a node is created whose text is taken from the key
/tikz/data visualization/legend entry options/text
• Also inside the picture, the code stored in the following key gets executed:
/tikz/data visualization/legend entry options/visualizer in legend
(no value)
Set this key to some code that paints something in the cell picture. Typically, this will be a
visual representation of the data set styling, but it could also be something different.
1
−1
0
1
a
spacer
b
−1
\tikz \datavisualization [
school book axes, visualize as line/.list={a,b},
style sheet=vary dashing,
a={label in legend={text=a}},
new legend entry={
text=spacer,
visualizer in legend={\draw[solid] (0,0) circle[radius=2pt];}
},
b={label in legend={text=b}}]
data point [x=-1, y=-1, set=a]
data point [x=1, y=0, set=a]
data point [x=-1, y=1, set=b]
data point [x=1, y=0.5, set=b];
The following styles are applied in the following order before the cell picture is filled:
1. /tikz/data visualization/every data set label with path /tikz/data visualization
2. /tikz/data visualization/every label in legend with path
/tikz/data visualization/legend entry options.
3. The hoptionsi.
4. The code in the following key:
/tikz/data visualization/legend entry options/setup
(no value)
Some code to be executed at this point. Mostly, it is used to setup attributes for style sheets.
5. A styling signal is emitted.
6. Only for the node: The current value of node style.
7. Only for the visualizer in legend: The styling that has been accumulated by calls to the following
key:
/tikz/data visualization/legend entry options/visualizer in legend style=
{hoptionsi}
(style, no default)
Calls to this key accumulate hoptionsi that will be executed with the path prefix /tikz at this
point.
858
As indicated earlier, the new legend entry key is called by the label in legend=hoptionsi key internally. In this case, the following extra hextra optionsi are passed to new legend entry key:
• The styling of the visualizer.
• The /tikz/data visualization/every label in legend style.
• The /tikz/every label style with path /tikz.
• Setting setup to /data point/set=hname of the visualizer i.
• The value of the label legend options that are stored in the visualizer. These options can be
changed using the following key:
/tikz/data visualization/visualizer options/label in legend options=hoptionsi
default)
(no
Use this key with a visualizer to configure the label in legend options. Typically, this key is used
only internally by a visualizer upon its creating to set the hoptionsi to setup the visualizer in
legend key.
79.9.10
Reference: Label in Legend Visualizers for Lines and Scatter Plots
Visualizers like visualize as line or visualize as smooth line use a label in legend visualizer that
draws a short line to represent the data set inside the legend. However, this line needs not be a simple
straight line, but can be a little curve or a small circle – indeed, even the default line is not a simple straight
line but rather a small zig-zag curve. To configure this line, the two keys are used, although you will only
rarely use them directly, but rather use one of the predefined styles mentioned later on.
Before we go into the glorious details of all of these keys, let us first have a look at the keys you are most
likely to use in practice: The keys for globally reconfiguring the default label in legend visualizers:
/tikz/data visualization/legend entry options/default label in legend path
(style, no value)
This style is set, by default, to zig zag label in legend line. It is installed by the styles straight
line, smooth line, and gap line, so changing this style will change the appearance of lines in legends.
The main other sensible option for this key is straight label in legend line.
1
−1
0
1
a
b
\tikz \datavisualization [
school book axes, visualize as
style sheet=vary dashing,
a={label in legend={text=a}},
data point [x=-1, y=-1, set=a]
data point [x=-1, y=1, set=b]
line/.list={a,b},
b={label in legend={text=b}}]
data point [x=1, y=0, set=a]
data point [x=1, y=0.5, set=b];
−1
1
−1
0
−1
1
a
b
\tikz \datavisualization [
school book axes, visualize as line/.list={a,b},
legend entry options/default label in legend path/.style=
straight label in legend line,
style sheet=vary dashing,
a={label in legend={text=a}}, b={label in legend={text=b}}]
data point [x=-1, y=-1, set=a]
data point [x=1, y=0, set=a]
data point [x=-1, y=1, set=b]
data point [x=1, y=0.5, set=b];
/tikz/data visualization/legend entry options/default label in legend closed path (style, no
value)
This style is executed by smooth cycle and straight cycle. There are (currently) no other predefined
sets of coordinates that can be used instead of the default value circular label in legend line.
/tikz/data visualization/legend entry options/default label in legend mark
(style, no value)
This style is executed by no lines and, implicitly, by scatter plots. The default is to use label in
legend line one mark. Another possible value is label in legend line three marks.
859
example a
example b
example c
\tikz \datavisualization [
visualize as scatter/.list={a,b,c},
style sheet=cross marks,
legend entry options/default label in legend mark/.style=
label in legend three marks,
a={label in legend={text=example a}},
b={label in legend={text=example b}},
c={label in legend={text=example c}}];
/tikz/data visualization/legend entry options/label in legend line coordinates=
{hlist of coordinatesi}
(no default)
This key takes a hlist of coordinatesi, which are Tik Z-coordinates separated by commas like (0,0),
(1,1). The effect of setting the key is the following: The label in legend visualizer used by, for instance,
visualize as line will draw a path going through these points. When the line is drawn, the exact
same style will be used as was used for the data set. For instance, if the smooth line key was used and
also the style=red key, the line through the hlist of coordinatesi will also be red and smooth. When
the straight cycle key was used, the coordinates will also be connected by a cycle, and so on.
When the line connecting the hlist of coordinatesi is drawn, the coordinate system will have been shifted
and transformed in such a way that (0,0) lies to the left of the text and at half the height of the character
“x”. This means that the right-most-point in the list should usually be (0,0) and all other x-coordinates
should usually be negative. When the text left options is used, the coordinate system will have been
flipped, so the hlist of coordinatesi is independent of whether the text is to the right or to the left of the
line.
Let us now have a look at a first, simple example. We create a legend entry that is just a straight line,
so it should start somewhere to the left of the origin at height 0 and go to the origin:
1
−1
0
1
a
b
−1
\tikz \datavisualization [
school book axes, visualize as line/.list={a,b},
style sheet=vary dashing,
a={label in legend={text=a,
label in legend line coordinates={(-1em,0), (0,0)}}},
b={label in legend={text=b,
label in legend line coordinates={(-2em,0), (0,0)}}}]
data point [x=-1, y=-1, set=a]
data point [x=1, y=0, set=a]
data point [x=-1, y=1, set=b]
data point [x=1, y=0.5, set=b];
Now let us make this a bit more fancy and useful by using shifted lines:
1
−1
0
1
b
a
−1
\tikz \datavisualization [
school book axes, visualize as line/.list={a,b},
legend={up then right}, style sheet=vary dashing,
a={label in legend={text=a,
label in legend line coordinates={(-2em,-.25ex), (0,0)}}},
b={label in legend={text=b,
label in legend line coordinates={(-2em,.25ex), (0,0)}}}]
data point [x=-1, y=-1, set=a]
data point [x=1, y=0, set=a]
data point [x=-1, y=1, set=b]
data point [x=1, y=0.5, set=b];
In the final example, we use a little “hat” to represent lines:
1
−1
0
−1
1
b
a
\tikz \datavisualization [
school book axes, visualize as line/.list={a,b},
legend={up then right}, style sheet=vary dashing,
a={label in legend={text=a,
label in legend line coordinates={
(-2em,-.2ex), (-1em,.2ex), (0,-.2ex)}}},
b={label in legend={text=b,
label in legend line coordinates={
(-2em,-.2ex), (-1em,.2ex), (0,-.2ex)}}}]
data point [x=-1, y=-1, set=a]
data point [x=1, y=0, set=a]
data point [x=-1, y=1, set=b]
data point [x=1, y=0.5, set=b];
/tikz/data visualization/legend entry options/label in legend mark coordinates=
{hlist of coordinatesi}
(no default)
860
This key is similar to label in legend line coordinates, but now the hlist of coordinatesi is used
as the positions where plot marks are shown. Naturally, plot marks are only shown there if they are also
shown by the visualizer in the actual data – just like the line through the coordinates of the previous
key is only shown when there is a line.
The hlist of coordinatesi may be the same as the one used for lines, but usually it is not. In general, it
is better to have marks for instance not at the ends of the line.
1
−1
0
1
b
a
−1
\tikz \datavisualization [
school book axes, visualize as line/.list={a,b},
legend={up then right},
style sheet=vary dashing,
style sheet=cross marks,
a={label in legend={text=a,
label in legend line coordinates={
(-2em,-.2ex), (-1em,.2ex), (0,-.2ex)},
label in legend mark coordinates={
(-1em,.2ex)}}},
b={label in legend={text=b,
label in legend line coordinates={
(-2em,-.2ex), (-1em,.2ex), (0,-.2ex)},
label in legend mark coordinates={
(-2em,-.2ex), (0,-.2ex)}}}]
data point [x=-1, y=-1, set=a]
data point [x=1, y=0, set=a]
data point [x=-1, y=1, set=b]
data point [x=1, y=0.5, set=b];
Naturally, you typically will not give coordinates explicitly for each label, but use one of the following
styles:
/tikz/data visualization/legend entry options/straight label in legend line
(no value)
Just gives a straight line and two plot marks.
example
\tikz \datavisualization [visualize as line,
line={style={mark=x}, label in legend={text=example,
straight label in legend line}}];
This style might seem like a good idea to use in general, but it does have a huge drawback: Some commonly used plot marks will be impossible to distinguish – even though there is no problem distinguishing
them in a graph.
bad example a
bad example b
bad example c
\tikz \datavisualization [visualize as line/.list={a,b,c},
legend entry options/default label in legend path/.style=
straight label in legend line,
a={style={mark=+}, label in legend={text=bad example a}},
b={style={mark=-}, label in legend={text=bad example b}},
c={style={mark=|}, label in legend={text=bad example c}}];
For this reason, this option is not the default, but rather the next one.
/tikz/data visualization/legend entry options/zig zag label in legend line
(no value)
Uses a small up-down-up line as the label in legend visualizer. The two plot marks are at the extremal
points of the line. It works pretty well in almost all situations and is the default.
better example a
better example b
better example c
\tikz \datavisualization [
visualize as line=a,
visualize as smooth line/.list={b,c},
a={style={mark=+}, label in legend={text=better example a}},
b={style={mark=-}, label in legend={text=better example b}},
c={style={mark=|}, label in legend={text=better example c}}];
Even though the above example shows that the marks are easier to distinguish than with a straight
line, the chosen marks are still not optimal. This is the reason that the cross marks style uses different
crosses:
861
good example a
good example b
good example c
\tikz \datavisualization [
visualize as line/.list={a,b},
visualize as smooth line=c,
style sheet=cross marks,
a={label in legend={text=good example a}},
b={label in legend={text=good example b}},
c={gap line, label in legend={text=good example c}}];
/tikz/data visualization/legend entry options/circular label in legend line
(no value)
This style is especially tailored to represent lines that are closed. It is automatically selected for instance
by the polygon or the smooth cycle styles.
0.75
0.5
0.25
0
−0.25
−0.5
−0.75
polygon
circle
line
−1 −0.5
0
0.5
1
\tikz \datavisualization [
scientific axes={clean}, all axes={length=3cm},
visualize as line/.list={a,b,c},
a={polygon}, b={smooth cycle},
style sheet=cross marks,
a={label in legend={text=polygon}},
b={label in legend={text=circle}},
c={label in legend={text=line}}]
data [format=function, set=a] {
var t : {0,72,...,359};
func x = cos(\value t);
func y = sin(\value t);
}
data [format=function, set=b] {
var t : [0:2*pi];
func x = .8*cos(\value t r);
func y = .8*sin(\value t r);
}
data point [x=-1, y=0.5, set=c]
data point [x=1, y=0.25, set=c];
/tikz/data visualization/legend entry options/gap circular label in legend line
(no value)
This style is especially tailored to for the gap cycle style and automatically selected by it:
0.75
0.5
0.25
0
−0.25
−0.5
−0.75
polygon
circle
line
−1 −0.5
0
0.5
1
\tikz \datavisualization [
scientific axes={clean}, all axes={length=3cm},
visualize as line/.list={a,b,c},
a={gap cycle}, b={smooth cycle}, c={gap line},
a={style={mark=*, mark size=0.5pt},
label in legend={text=polygon}},
b={label in legend={text=circle}},
c={style={mark=*, mark size=0.5pt, mark options=red},
label in legend={text=line}}]
data [format=function, set=a] {
var t : {0,72,...,359};
func x = cos(\value t);
func y = sin(\value t);
}
data [format=function, set=b] {
var t : [0:352];
func x = .8*cos(\value t);
func y = .8*sin(\value t);
}
data point [x=-1, y=0.5, set=c]
data point [x=1, y=0.25, set=c];
/tikz/data visualization/legend entry options/label in legend one mark
(no value)
To be used with scatter plots, since no line is drawn. Just displays a single mark (this is the default
with a scatter plot or when the no line is selected.
example a
example b
example c
\tikz \datavisualization [visualize as scatter/.list={a,b,c},
style sheet=cross marks,
a={label in legend={text=example a}},
b={label in legend={text=example b}},
c={label in legend={text=example c}}];
862
/tikz/data visualization/legend entry options/label in legend three marks
(no value)
An alternative to the previous style, where several marks are shown.
example a
example b
example c
\tikz \datavisualization [visualize as scatter/.list={a,b,c},
style sheet=cross marks,
a={label in legend={text=example a, label in legend three marks}},
b={label in legend={text=example b, label in legend three marks}},
c={label in legend={text=example c, label in legend three marks}}];
863
80
Polar Axes
80.1
Overview
Tik Z Library datavisualization.polar
\usetikzlibrary{datavisualization.polar} % LATEX and plain TEX
\usetikzlibrary[datavisualization.polar] % ConTEXt
This library contains keys that allow you to create plots in a polar axis system is used.
In a polar axis system two attributes are visualized by displacing a data point as follows: One attribute
is used to compute a an angle (a direction) while a second attribute is used as a radius (a distance). The
angle can be measured in degrees, radians, or can be scaled arbitrarily.
1
π
2
7
π
12
2
π
3
5
π
12
\tikz \datavisualization [
scientific polar axes={0 to pi, clean},
all axes=grid,
style sheet=vary hue,
legend=below
]
[visualize as smooth line=sin,
sin={label in legend={text=$1+\sin \alpha$}}]
data [format=function] {
var angle : interval [0:pi];
func radius = sin(\value{angle}r) + 1;
}
[visualize as smooth line=cos,
cos={label in legend={text=$1+\cos\alpha$}}]
data [format=function] {
var angle : interval [0:pi];
func radius = cos(\value{angle}r) + 1;
};
1
π
3
3
π
4
1
π
4
5
π
6
1
π
6
11
π
12
1
π
12
π
0
2
1.5
1
0.5
0
1 + sin α
0.5
1
1.5
2
1 + cos α
Most of the time, in order to create a polar axis system, you will just use the scientific polar axes
key, which takes a number of options that allow you to configure the axis system in greater detail. This key
is documented in Section 80.2. Internally, this key uses more low level keys which are documented in the en
suite sections.
It is worthwhile to note that the axes of a polar axis system are, still, normal axes of the data visualization
system. In particular, all the configurations possible for, say, Cartesian axes also apply to the “angle axis”
and the “radius axis” of a polar axis system. For instance, you can could make both axes logarithmic or style
their ticks:
0.1
8
8
6
6
4
4
2
2
0
0
5
10
15
1
20
2
2
4
3
6
4
5
8
20
15
10
864
\tikz[baseline] \datavisualization [
scientific axes={clean},
x axis={attribute=angle, ticks={minor steps between steps=4}},
y axis={attribute=radius, ticks={some, style=red!80!black}},
all axes=grid,
visualize as smooth line=sin]
data [format=function] {
var t : interval [-3:3];
func angle = exp(\value t);
func radius = \value{t}*\value{t};
};
\qquad
\tikz[baseline] \datavisualization [
scientific polar axes={right half clockwise, clean},
angle axis={logarithmic,
ticks={
minor steps between steps=8,
major also at/.list={2,3,4,5,15,20}}},
radius axis={ticks={some, style=red!80!black}},
all axes=grid,
visualize as smooth line=sin]
data [format=function] {
var t : interval [-3:3];
func angle = exp(\value t);
func radius = \value{t}*\value{t};
};
80.2
Scientific Polar Axis System
/tikz/data visualization/scientific polar axes=hoptionsi
(no default)
This key installs a polar axis system that can be used in a “scientific” publication. Two axes are created
called the angle axis and the radius axis. Unlike “normal” Cartesian axes, these axes do not point
in a specific direction. Rather, the radius axis is used to map the values of one attribute to a distance
from the origin while the angle axis is used to map the values of another attribute to a rotation angle.
The hoptionsi will be executed with the path prefix
/tikz/data visualization/scientific polar axes
The permissible keys are documented in the later subsections of this section.
Let us start with the configuration of the radius axis since it is easier. Firstly, you should specify
which attribute is linked to the radius. The default is radius, but you will typically wish to change
this. As with any other axis, the attribute key is used to configure the axis, see Section 77.2.2
for details. You can also apply all other configurations to the radius axis like, say, unit length or
length or style. Note, however, that the logarithmic key will not work with the radius axis for a
scientific polar axes system since the attribute value zero is always placed at the center – and for
a logarithmic plot the value 0 cannot be mapped.
865
90◦
105◦
75◦
120◦
60◦
10,000
135◦
45◦
150◦
30◦
5,000
165◦
15◦
180◦
10,000
0
5,000
5,000
10,000
195◦
0◦
\tikz \datavisualization [
scientific polar axes,
radius axis={
attribute=distance,
ticks={step=5000},
padding=1.5em,
length=3cm,
grid
},
visualize as smooth line]
data [format=function] {
var angle : interval [0:100];
func distance = \value{angle}*\value{angle};
};
345◦
5,000
210◦
330◦
225◦
315◦
10,000
240◦
300◦
255◦
285◦
270◦
For the angle axis, you can also specify an attribute using the attribute key. However, for this axis
the mapping of a value to an actual angle is a complicated process involving many considerations of
how the polar axis system should be visualized. For this reason, there are a large number of predefined
such mappings documented in Section 80.2.2.
Finally, as for a scientific plot, you can configure where the ticks should be shown using the keys
inner ticks, outer ticks, and clean, documented below.
80.2.1
Tick Placements
/tikz/data visualization/scientific polar axes/outer ticks
(no value)
This key, which is the default, causes ticks to be drawn “outside” the outer “ring” of the polar axes:
90◦
100
105◦
120◦
135◦
75◦
60◦
45◦
75
150◦
30◦
50
165◦
15◦
25
180◦
100
75
50
0
25
\tikz \datavisualization [
scientific polar axes={outer ticks, 0 to 180},
visualize as smooth line]
data [format=function] {
var angle : interval [0:100];
func radius = \value{angle};
};
25
50
75
0◦
100
/tikz/data visualization/scientific polar axes/inner ticks
(no value)
This key causes the ticks to be “turned to the inside.” I do not recommend using this key.
105◦
120◦
135◦
75◦
60◦
45◦
75
150◦
30◦
50
165◦
180◦
100
90◦
100
15◦
25
75
50
25
0
25
50
75
0◦
100
866
\tikz \datavisualization [
scientific polar axes={inner ticks, 0 to 180},
visualize as smooth line]
data [format=function] {
var angle : interval [0:100];
func radius = \value{angle};
};
/tikz/data visualization/scientific polar axes/clean
(no value)
This key separates the area where the data is shown from the area where the ticks are shown. Usually,
this is the best choice for the tick placement since it avoids a collision of data and explanations.
90◦
105◦
60◦
135◦
45◦
150◦
30◦
165◦
15◦
180◦
0◦
100
80.2.2
\tikz \datavisualization [
scientific polar axes={clean, 0 to 180},
visualize as smooth line]
data [format=function] {
var angle : interval [0:100];
func radius = \value{angle};
};
75◦
120◦
75
50
25
0
25
50
75
100
Angle Ranges
Suppose you create a polar plot in which the radius values vary between, say, 567 and 1234. Then the normal
axis scaling mechanisms can be used to compute a good scaling for the “radius axis”: Place the value 1234
at a distance of , say, 5 cm from the origin and place the value 0 at the origin. Now, by comparison, suppose
that the values of the angle axis’s attribute ranged between, say, 10 and 75.7. In this case, we may wish the
angles to be scaled so that the minimum value is horizontal and the maximum value is vertical. But we may
also wish the a value of 0 is horizontal and a value of 90 is vertical.
Since it is unclear which interpretation is the right one, you have to use an option to select which should
happen. The applicable options fall into three categories:
• Options that request the scaling to be done in such a way that the attribute is interpreted as a value
in degrees and such that the minimum and maximum of the depicted range is a multiple of 90◦ . For
instance, the option 0 to 180 causes the angle axis to range from 0◦ to 180◦ , independently of the
actual range of the values.
• Options that work as above, but use radians rather than degrees. An example is the option 0 to pi.
• Options that map the minimum value in the data to a horizontal or vertical line and the maximum
value to another such line. This is useful when the values neither directly correspond to degrees or
radians. In this case, the angle axis may also be a logarithmic axis.
In addition to the above categories, all of the option documented in the following implicitly also select
quadrants that are used to depict the data. For instance, the 0 to 90 key and also the 0 to pi half key
setup the polar axis system in such a way that only first (upper right) quadrant is used. No check is done
whether the data fill actually lie in this quadrant – if it does not, the data will “bleed outside” the range.
Naturally, with a key like 0 to 360 or 0 to 2pi this cannot happen.
In order to save some space in this manual, in the following the different possible keys are only given in
a table together with a small example for each key. The examples were created using the following code:
90◦
60◦
30◦
1
0◦
0
0
1
\tikz \datavisualization [
scientific polar axes={
clean,
0 to 90 % the option
},
angle axis={ticks={step=30}},
radius axis={length=1cm, ticks={step=1}},
visualize as scatter]
data point [angle=20, radius=0.5]
data point [angle=30, radius=1]
data point [angle=40, radius=1.5];
For the options on radians, the angle values have been replaced by 0.2, 0.3, and 0.4 and the stepping
has been changed by setting step=(pi/6). For the quadrant options, no stepping is set at all (it is computed
automatically).
867
Option
With clean ticks
90◦
0◦
0
-90 to 0
0
1
0
1
1
−30◦
1
−30◦
−60◦
90◦
60◦
180◦
120◦
150◦
0◦
0
90◦
−90◦
90◦
0◦
0
−30◦
1
60◦
270◦
90◦
300◦
60◦
−150◦
−120◦
1
−90◦
−60◦
60◦
30◦
0◦
−30◦
−60◦
1
0
1
210◦
240◦
1
330◦
300◦
270◦
90◦
0◦
1
60◦
30◦
1
0
1
−150◦
−120◦
1
−30◦
−60◦
0◦
−30◦
90◦
0◦
1
120◦
150◦
30◦
0
1
60◦
30◦
180◦
330◦
150◦
180◦
120◦
150◦
0◦
1
210◦
120◦
−90◦
0◦
60◦
30◦
1
30◦
0
0
1
−60◦
150◦
1
90◦
30◦
1
90◦
1
60◦
0
240◦
180◦
1
1
-180 to 180
−90◦
−60◦
30◦
180◦
0◦
1
1
0 to 360
1
0
150◦
120◦
0
0◦
120◦
-90 to 90
1
60◦
30◦
0
−90◦
0 to 180
90◦
30◦
1
0 to 90
With outer ticks
60◦
180◦
868
−90◦
0◦
Option
With clean ticks
1
π
2
1
π
3
0
-pi half to 0
1
0
1
0
0
1
π
2
2
π
3
1
π
3
5
π
6
1
π
6
5
π
6
0
π
π
1
0
1
0
− 16 π
1
π
2
2
π
3
1
π
3
1
1
π
2
1
π
3
1
0
1
π
6
0
0
1
π
6
0
− 13 π
1
1
π
3
1
-pi half to pi half
0
1
1
1
π
2
1
− 12 π
− 13 π
1
π
6
0
0
1
− 16 π
− 12 π
1
π
3
1
0
0
1
0 to pi
1
π
2
1
π
6
1
0 to pi half
With outer ticks
1
π
6
0
0
1
1
− 12 π
2
π
3
1
π
2
1
π
3
5
π
6
0
π
1 56 π
1 13 π
2
π
3
1 12 π
1 23 π
1
π
2
0
π
− 23 π
1
− 16 π
− 56 π
− 12 π
1
5
π
6
π
0
1 16 π
1 13 π
1
π
6
− 13 π
869
− 16 π
− 13 π
1
π
3
1
0
1
π
3
5
π
6
1
π
2
2
π
3
1
1
1 16 π
-pi to pi
1
π
6
π
0
− 12 π
− 13 π
5
π
6
0 to 2pi
1
− 16 π
0
1
1 56 π
1 12 π
1
π
2
2
π
3
1
π
6
1 23 π
1
π
3
1
1
0
− 56 π
− 23 π
1
− 12 π
1
π
6
0
1
− 16 π
− 13 π
Option
With clean ticks
40
0
1
20
25
fourth quadrant
1
0
1
0
35
30
fourth quadrant clockwise
20
25
0
1
0
40
0
40
1
lower half
0
1
1
0
1
20
40
25
20
1
0
870
40
0
1
1
0
1
40
35
30
1
1
25
30
20
1
25
20
35
0
1
20
35
40
25
30
35
30
lower half clockwise
35
25
40
1
20
30
35
20
1
25
30
upper half clockwise
35
30
30
1
25
25
35
20
1
40
40
25
40
1
1
30
upper half
0
0
35
35
1
20
25
30
30
35
40
0
1
20
1
25
1
40
1
1
20
40
0
30
25
20
0
30
35
0
35
1
20
0
1
quadrant clockwise
40
30
25
1
quadrant
With outer ticks
35
40
0
35
1
20
25
30
Option
With clean ticks
With outer ticks
20
20
25
25
1
left half
30
1
0
30
0
1
1
35
35
40
40
40
40
35
35
1
left half clockwise
30
1
0
30
0
1
1
25
25
20
20
40
40
35
35
1
right half
1
0
30
1
0
1
25
25
20
20
20
20
25
25
1
right half clockwise
1
0
30
1
0
30
1
35
40
80.3
30
35
40
Advanced: Creating a New Polar Axis System
/tikz/data visualization/new polar axes={hangle axis namei}{hradius axis namei}
(no default)
This key actually creates two axes, whose names are give as parameters: An angle axis and a radius axis.
These two axes work in concert in the following way: Suppose a data point has two attributes called
angle and radius (these attribute names can be changed by changing the attribute of the hangle axis
namei or the hradius axis namei, respectively). These two attributes are then scaled as usual, resulting
in two “reasonable” values a (for the angle) and r (for the radius). Then, the data point gets visualized
(in principle, details will follow) at a position on the page that is at a distance of r from the origin and
at an angle of a.
\tikz \datavisualization
[new polar axes={angle axis}{radius axis},
radius axis={length=2cm},
visualize as scatter]
data [format=named] {
angle={0,20,...,160}, radius={0,...,5}
};
In detail, the hangle axisi keeps track of two vectors v0 and v90 , each of which will usually have unit
length (length 1pt) and which point in two different directions. Given a radius r (measured in TEX pts,
so if the radius attribute 10pt, then r would be 10) and an angle a, let s be the sine of a and let c be
the cosine of a, where a is a number is degrees (so s would be 1 for a = 90). Then, the current page
position is shifted by c · r times v0 and, additionally, by s · r times v90 . This means that in the “polar
coordinate system” v0 is the unit vector along the “0◦ -axis” and v90 is the unit vector along “90◦ -axis”.
The values of v0 and v90 can be changed using the following key on the hangle axisi:
871
/tikz/data visualization/axis options/unit vectors={hunit vector 0 degreesi}{hunit vector 90
degreesi}
(no default, initially {(1pt,0pt)}{(0pt,1pt)})
Both the hunit vector 0 degreesi and the hunit vector 90 degreesi are Tik Z coordinates:
\tikz \datavisualization
[new polar axes={angle axis}{radius axis},
radius axis={unit length=1cm},
angle axis={unit vectors={(10:1pt)}{(60:1pt)}},
visualize as scatter]
data [format=named] {
angle={0,90}, radius={0.25,0.5,...,2}
};
Once created, the angle axis can be scaled conveniently using the following keys:
/tikz/data visualization/axis options/degrees
(no value)
When this key is passed to the angle axis of a polar axis system, it sets up the scaling so that a value
of 360 on this axis corresponds to a complete circle.
\tikz \datavisualization
[new polar axes={angle axis}{radius axis},
radius axis={unit length=1cm},
angle axis={degrees},
visualize as scatter]
data [format=named] {
angle={10,90}, radius={0.25,0.5,...,2}
};
/tikz/data visualization/axis options/radians
(no value)
In contrast to degrees, this option sets up things so that a value of 2*pi on this axis corresponds to a
complete circle.
\tikz \datavisualization
[new polar axes={angle axis}{radius axis},
radius axis={unit length=1cm},
angle axis={radians},
visualize as scatter]
data [format=named] {
angle={0,1.5}, radius={0.25,0.5,...,2}
};
872
81
81.1
The Data Visualization Backend
Overview
The present section explains the mechanisms behind the data visualization engine.
Until it is documented properly, we will have to make do with the documentation in the source code.
81.2
The Rendering Pipeline
To be written...
81.3
Usage
To be written...
81.4
The Mathematical Micro-Kernel
To be written...
873
Part VII
Utilities
by Till Tantau
The utility packages are not directly involved in creating graphics, but you may find them useful nonetheless.
All of them either directly depend on pgf or they are designed to work well together with pgf even though
they can be used in a stand-alone way.
f (x)
x2
3
2 14
2
1
Z
3/2
x2 dx
0
x
1
1 12
2
3
\begin{tikzpicture}[scale=2]
\shade[top color=blue,bottom color=gray!50] (0,0) parabola (1.5,2.25) |- (0,0);
\draw (1.05cm,2pt) node[above] {$\displaystyle\int_0^{3/2} \!\!x^2\mathrm{d}x$};
\draw[help lines] (0,0) grid (3.9,3.9)
[step=0.25cm]
(1,2) grid +(1,1);
\draw[->] (-0.2,0) -- (4,0) node[right] {$x$};
\draw[->] (0,-0.2) -- (0,4) node[above] {$f(x)$};
\foreach \x/\xtext in {1/1, 1.5/1\frac{1}{2}, 2/2, 3/3}
\draw[shift={(\x,0)}] (0pt,2pt) -- (0pt,-2pt) node[below] {$\xtext$};
\foreach \y/\ytext in {1/1, 2/2, 2.25/2\frac{1}{4}, 3/3}
\draw[shift={(0,\y)}] (2pt,0pt) -- (-2pt,0pt) node[left] {$\ytext$};
\draw (-.5,.25) parabola bend (0,0) (2,4) node[below right] {$x^2$};
\end{tikzpicture}
874
82
Key Management
This section describes the package pgfkeys. It is loaded automatically by both pgf and Tik Z.
\usepackage{pgfkeys} % LATEX
\input pgfkeys.tex
% plain TEX
\usemodule[pgfkeys] % ConTEXt
This package can be used independently of pgf. Note that no other package of pgf needs to be loaded
(so neither the emulation layer nor the system layer is needed). The ConTEXt abbreviation is pgfkey
if pgfmod is not loaded.
82.1
82.1.1
Introduction
Comparison to Other Packages
The pgfkeys package defines a key–value management system that is in some sense similar to the more
light-weight keyval system and the improved xkeyval system. However, pgfkeys uses a slightly different
philosophy than these systems and it will coexist peacefully with both of them.
The main differences between pgfkeys and xkeyval are the following:
• pgfkeys organizes keys in a tree, while keyval and xkeyval use families. In pgfkeys the families
correspond to the root entries of the key tree.
• pgfkeys has no save-stack impact (you will have to read the TEXBook very carefully to appreciate
this).
• pgfkeys is slightly slower than keyval, but not much.
• pgfkeys supports styles. This means that keys can just stand for other keys (which can stand for other
keys in turn or which can also just execute some code). Tik Z uses this mechanism heavily.
• pgfkeys supports multi-argument key code. This can, however, be emulated in keyval.
• pgfkeys supports handlers. These are call-backs that are called when a key is not known. They are
very flexible, in fact even defining keys in different ways is handled by, well, handlers.
82.1.2
Quick Guide to Using the Key Mechanism
The following quick guide to pgf’s key mechanism only treats the most commonly used features. For an
in-depth discussion of what is going on, please consult the remainder of this section.
Keys are organized in a large tree that is reminiscent of the Unix file tree. A typical key might be, say,
/tikz/coordinate system/x or just /x. Again as in Unix, when you specify keys you can provide the
complete path of the key, but you usually just provide the name of the key (corresponding to the file name
without any path) and the path is added automatically.
Typically (but not necessarily) some code is associated with a key. To execute this code, you use the
\pgfkeys command. This command takes a list of so-called key–value pairs. Each pair is of the form
hkeyi=hvaluei. For each pair the \pgfkeys command will execute the code stored for the hkeyi with its
parameter set to hvaluei.
Here is a typical example of how the \pgfkeys command is used:
\pgfkeys{/my key=hallo,/your keys/main key=something\strange,
key name without path=something else}
Now, to set the code that is stored in a key you do not need to learn a new command. Rather, the
\pgfkeys command can also be used to set the code of a key. This is done using so-called handlers. They
look like keys whose names look like “hidden files in Unix” since they start with a dot. The handler for
setting the code of a key is appropriately called /.code and it is used as follows:
The value is ’hi!’.
\pgfkeys{/my key/.code=The value is ’#1’.}
\pgfkeys{/my key=hi!}
As you can see, in the first line we defined the code for the key /my key. In the second line we executed
this code with the parameter set to hi!.
875
There are numerous handlers for defining a key. For instance, we can also define a key whose value
actually consists of more than one parameter.
The values are ’a1’ and ’a2’.
\pgfkeys{/my key/.code 2 args=The values are ’#1’ and ’#2’.}
\pgfkeys{/my key={a1}{a2}}
We often want to have keys where the code is called with some default value if the user does not provide
a value. Not surprisingly, this is also done using a handler, this time called /.default.
(hallo)(hello)
\pgfkeys{/my key/.code=(#1)}
\pgfkeys{/my key/.default=hello}
\pgfkeys{/my key=hallo,/my key}
The other way round, it is also possible to specify that a value must be specified, using a handler called
/.value required. Finally, you can also require that no value may be specified using /.value forbidden.
All keys for a package like, say, Tik Z start with the path /tikz. We obviously do not like to write this
path down every time we use a key (so we do not have to write things like \draw[/tikz/line width=1cm]).
What we need is to somehow “change the default path to a specific location.” This is done using the handler
/.cd (for “change directory”). Once this handler has been used on a key, all subsequent keys in the current
call of \pgfkeys only are automatically prefixed with this path, if necessary.
Here is an example:
\pgfkeys{/tikz/.cd,line width=1cm,line cap=round}
This makes it easy to define commands like \tikzset, which could be defined as follows (the actual
definition is a bit faster, but the effect is the same):
\def\tikzset#1{\pgfkeys{/tikz/.cd,#1}}
When a key is handled, instead of executing some code, the key can also cause further keys to be executed.
Such keys will be called styles. A style is, in essence, just a key list that should be executed whenever the
style is executed. Here is an example:
(a:foo)(b:bar)(a:wow)
\pgfkeys{/a/.code=(a:#1)}
\pgfkeys{/b/.code=(b:#1)}
\pgfkeys{/my style/.style={/a=foo,/b=bar,/a=#1}}
\pgfkeys{/my style=wow}
As the above example shows, styles can also be paramaterized, just like the normal code keys.
As a typical use of styles, suppose we wish to set up the key /tikz so that it will change the default path
to /tikz. This can be achieved as follows:
\pgfkeys{/tikz/.style=/tikz/.cd}
\pgfkeys{tikz,line width=1cm,draw=red}
Note that when \pgfkeys is executed, the default path is set to /. This means that the first tikz will
be completed to /tikz. Then /tikz is a style and, thus, replaced by /tikz/.cd, which changes the default
path to /tikz. Thus, the line width is correctly prefixed with /tikz.
82.2
The Key Tree
The pgfkeys package organizes keys in a so-called key tree. This tree will be familiar to anyone who has
used a Unix operating system: A key is addressed by a path, which consists of different parts separated
by slashes. A typical key might be /tikz/line width or just /tikz or something more complicated like
/tikz/cs/x/.store in.
Let us fix some further terminology: Given a key like /a/b/c, we call the part leading up the last slash
(/a/b) the path of the key. We call everything after the last slash (c) the name of the key (in a file system
this would be the file name).
We do not always wish to specify keys completely. Instead, we usually specify only part of a key (typically
only the name) and the default path is then added to the key at the front. So, when the default path is /tikz
and you refer to the (partial) key line width, the actual key that is used is /tikz/line width. There is a
simple rule for deciding whether a key is a partial key or a full key: If it starts with a slash, then it is a full
key and it is not modified; if it does not start with a slash, then the default path is automatically prefixed.
Note that the default path is not the same as a search path. In particular, the default path is just a
single path. When a partial key is given, only this single default path is prefixed; pgfkeys does not try to
876
look up the key in different parts of a search path. It is, however, possible to emulate search paths, but a
much more complicated mechanism must be used.
When you set keys (to be explained in a moment), you can freely mix partial and full keys and you can
change the default path. This makes it possible to temporarily use keys from another part of the key tree
(this turns out to be a very useful feature).
Each key (may) store some tokens and there exist commands, described below, for setting, getting, and
changing the tokens stored in a key. However, you will only very seldom use these commands directly.
Rather, the standard way of using keys is the \pgfkeys command or some command that uses it internally
like, say, \tikzset. So, you may wish to skip the following commands and continue with the next subsection.
\pgfkeyssetvalue{hfull keyi}{htoken texti}
Stores the htoken texti in the hfull keyi. The hfull keyi may not be a partial key, so no default-path-adding
is done. The htoken texti can be arbitrary tokens and may even contain things like # or unbalanced
TEX-ifs.
Hello, world!
\pgfkeyssetvalue{/my family/my key}{Hello, world!}
\pgfkeysvalueof{/my family/my key}
The setting of a key is always local to the current TEX group.
\pgfkeyslet{hfull keyi}{hmacroi}
Performs a \let statement so the hfull keyi points to the contents of hmacroi.
Hello, world!
\def\helloworld{Hello, world!}
\pgfkeyslet{/my family/my key}{\helloworld}
\pgfkeysvalueof{/my family/my key}
You should never let a key be equal to \relax. Such a key may or may not be indistinguishable from
an undefined key.
\pgfkeysgetvalue{hfull keyi}{hmacroi}
Retrieves the tokens stored in the hfull keyi and lets hmacroi be equal to these tokens. If the key has
not been set, the hmacroi will be equal to \relax.
Hello, world!
\pgfkeyssetvalue{/my family/my key}{Hello, world!}
\pgfkeysgetvalue{/my family/my key}{\helloworld}
\helloworld
\pgfkeysvalueof{hfull keyi}
Inserts the value stored in hfull keyi at the current position into the text.
Hello, world!
\pgfkeyssetvalue{/my family/my key}{Hello, world!}
\pgfkeysvalueof{/my family/my key}
\pgfkeysifdefined{hfull keyi}{hif i}{helsei}
Checks whether this key was previously set using either \pgfkeyssetvalue or \pgfkeyslet. If so, the
code in hif i is executed, otherwise the code in helsei.
This command will use eTEX’s \ifcsname command, if available, for efficiency. This means, however,
that it may behave differently for TEX and for eTEX when you set keys to \relax. For this reason you
should not do so.
yes
82.3
\pgfkeyssetvalue{/my family/my key}{Hello, world!}
\pgfkeysifdefined{/my family/my key}{yes}{no}
Setting Keys
Settings keys is done using a powerful command called \pgfkeys. This command takes a list of so-called
key–value pairs. These are pairs of the form hkeyi=hvaluei. The principle idea is the following: For each pair
in the list, some action is taken. This action can be one of the following:
877
1. A command is executed whose argument(s) are hvaluei. This command is stored in a special subkey
of hkeyi.
2. The hvaluei is stored in the hkeyi itself.
3. If the key’s name (the part after the last slash) is a known handler, then this handler will take care of
the key.
4. If the key is totally unknown, one of several possible unknown key handlers is called.
Additionally, if the hvaluei is missing, a default value may or may not be substituted. Before we plunge
into all the details, let us have a quick look at the command itself.
\pgfkeys{hkey listi}
The hkey listi should be a list of key–value pairs, separated by commas. A key–value pair can have the
following two forms: hkeyi=hvaluei or just hkeyi. Any spaces around the hkeyi or around the hvaluei
are removed. It is permissible to surround both the hkeyi or the hvaluei in curly braces, which are also
removed. Especially putting the hvaluei in curly braces needs to be done quite often, namely whenever
the hvaluei contains an equal-sign or a comma.
The key–value pairs in the list are handled in the order they appear. How this handling is done, exactly,
is described in the rest of this section.
If a hkeyi is a partial key, the current value of the default path is prefixed to the hkeyi and this “upgraded”
key is then used. The default path is just the root path / when the first key is handled, but it may
change later on. At the end of the command, the default path is reset to the value it had before this
command was executed.
Calls of this command may be nested. Thus, it is permissible to call \pgfkeys inside the code that is
executed for a key. Since the default path is restored after a call of \pgfkeys, the default path will not
change when you call \pgfkeys while executing code for a key (which is exactly what you want).
\pgfqkeys{hdefault pathi}{hkey listi}
This command has the same effect as \pgfkeys{hdefault pathi/.cd,hkey listi}, it is only marginally
quicker. This command should not be used in user code, but rather in commands like \tikzset or
\pgfset that get called very often.
\pgfkeysalso{hkey listi}
This command has exactly the same effect as \pgfkeys, only the default path is not modified before or
after the keys are being set. This command is mainly intended to be called by the code that is being
processed for a key.
\pgfqkeysalso{hdefault pathi}{hkey listi}
This command has the same effect as \pgfkeysalso{hdefault pathi/.cd,hkey listi}, it is only quicker.
Changing the default path inside a \pgfkeyalso is dangerous, so use with care. A rather safe place to
call this command is at the beginning of a TEX group.
82.3.1
First Char Syntax Detection
Usually, keys are of the form hkeyi=hvaluei and how such keys are handled is discussed in the rest of this
section. However, it is also possible to setup a different syntax for certain parts of the input to \pgfkeys.
Since this is a rather advanced option, most readers may wish to skip the following discussion upon first
reading; it is discussed here because this special syntax detection is the very first thing that is done when a
key is processed, before any of the following operations are performed.
The \pgfkeys command and its variants decompose their input into a list of hstringis that are separated
by commas. By default, each such hstringi must either have the form hkeyi=hvaluei or of the form hkeyi with
the value-part missing. However, you might wish to interpret some of these strings differently. For instance,
when a hstringi has the form "htexti", you might wish the hstringi to be interpreted as if one had written
label text={htexti}. Then, people could write
\myset{red, "main valve", thick}
instead of the more cumbersome
878
\myset{red, label text=main valve, thick}
An example where such a syntax reinterpretation is done is the quotes library, which allows you to write
things like
a
1
b
0
\tikz \graph { a ->["1" red] b ->["0"] c };
c
instead of the somewhat longer
a
1
b
0
\tikz \graph { a ->[edge node={node[red,auto]{1}}] b ->[edge label=0] c };
c
In order to detect whether a hstringi has a special syntax, you can request that the first character of
hstringi is analysed by the key parser. If this first character matches a character that has been flagged as a
special character, the hstringi is not interpreted as a usual key–value pair. Instead, hstringi is passed as a
parameter to a special macro that should take care of the hstringi. After this macro has finished, the parsing
continues with the hnext stringi in the list.
In order to setup a special syntax handling for hstringsi that begin with a certain character, two things
need to be done:
1. First, the whole first char syntax detection must be “switched on,” since, by default, it is turned off for
efficiency reasons (the overhead is rather small, however). This is done by setting the following key:
/handlers/first char syntax=htrue or falsei
(default true, initially false)
2. Second, in order to handle strings starting with a certain hcharacter i in a special way, you need to
store a macro in the following key:
/handlers/first char syntax/hmeaning of character i
(no value)
The hmeaning of character i should be the text that TEX’s command \meaning returns for a macro
that has been \let to the hcharacter i. For instance, when strings starting with " should be treated
in a special way, the hmeaning of character i would be the string the character " since this is
what TEX writes when you say
the character "
\let\mycharacter="
\meaning\mycharacter
Now, the key /handlers/first char syntax/hmeaning of character i should be setup (using
\pgfkeyssetvalue or using the .initial handler) to store a hmacro namei.
If this is the case and if hstringi starts with the hcharacter i (blanks at the beginning of hstringi
are deleted prior to this test), then hmacro namei is called with hstringi as its argument.
Let us now have a look at an example. We install two handlers, one for strings starting with " and one
for strings starting with <.
Quoted:
"foo".
Pointed:
.
\pgfkeys{
/handlers/first char syntax=true,
/handlers/first char syntax/the character "/.initial=\myquotemacro,
/handlers/first char syntax/the character }
Naturally, in the above examples, the two handling macros did not do something particularly exciting.
In the next example, we setup a more elaborate macro that mimics a small part the behaviour of the quotes
library, only for single quotes:
879
’foo’
bar
\pgfkeys{
/handlers/first char syntax=true,
/handlers/first char syntax/the character ’/.initial=\mysinglequotemacro
}
\def\mysinglequotemacro#1{\pgfkeysalso{label={#1}}}
\tikz \node [circle, ’foo’, draw] {bar};
Note that in the above example, the macro \mysinglequotemacro gets passed the complete string,
including the single quotes. It is the job of the macro to get rid of them, if this is necessary.
The first char syntax detection allows you to perform rather powerful transformations on the syntax of
keys – provided you can “pin down” the syntax on the first character. In the following example, you can
write expressions in parentheses in front of a key–value pair and the pair will only be executed when the
expression evaluates to true:
x
x
x x
\pgfkeys{
/handlers/first char syntax=true,
/handlers/first char syntax/the character (/.initial=\myparamacro
}
\def\myparamacro#1{\myparaparser#1\someendtext}
\def\myparaparser(#1)#2\someendtext{
\pgfmathparse{#1}
\ifx\pgfmathresult\onetext
\pgfkeysalso{#2}
\fi
}
\def\onetext{1}
\foreach \i in {1,...,4}
\tikz \node [draw, thick, rectangle, (pi>\i) circle, (pi>\i*2) draw=red] {x};
82.3.2
Default Arguments
The arguments of the \pgfkeys command can either be of the form hkeyi=hvaluei or of the form hkeyi with
the value-part missing. In the second case, the \pgfkeys will try to provide a default value for the hvaluei.
If such a default value is defined, it will be used as if you had written hkeyi=hdefault valuei.
In the following, the details of how default values are determined is described; however, you should
normally use the handlers /.default and /.value required as described in Section 82.4.2 and you may
wish to skip the following details.
When \pgfkeys encounters a hkeyi without an equal-sign, the following happens:
1. The input is replaced by hkeyi=\pgfkeysnovalue. In particular, the commands \pgfkeys{my key}
and \pgfkeys{my key=\pgfkeysnovalue} have exactly the same effect and you can “simulate” a missing value by providing the value \pgfkeysnovalue, which is sometimes useful.
2. If the hvaluei is \pgfkeysnovalue, then it is checked whether the subkey hkeyi/.@def exists. For
instance, if you write \pgfkeys{/my key}, then it is checked whether the key /my key/.@def exists.
3. If the key hkeyi/.@def exists, then the tokens stored in this key are used as hvaluei.
4. If the key does not exist, then \pgfkeysnovalue is used as the hvaluei.
5. At the end, if the hvaluei is now equal to \pgfkeysvaluerequired, then the code (or something fairly
equivalent) \pgfkeys{/errors/value required=hkeyi{}} is executed. Thus, by changing this key
you can change the error message that is printed or you can handle the missing value in some other
way.
82.3.3
Keys That Execute Commands
After the transformation process described in the previous subsection, we arrive at a key of the form
hkeyi=hvaluei, where hkeyi is a full key. Different things can now happen, but always the macro
\pgfkeyscurrentkey will have been set up to expand to the text of the hkeyi that is currently being
processed.
880
The first things that is tested is whether the key hkeyi/.@cmd exists. If this is the case, then it is assumed
that this key stores the code of a macro and this macro is executed. The argument of this macro is hvaluei
directly followed by \pgfeov, which stands for “end of value.” The hvaluei is not surrounded by braces.
After this code has been executed, \pgfkeys continues with the next key in the hkey listi.
It may seem quite peculiar that the macro stored in the key hkeyi/.@cmd is not simply executed with the
argument {hvaluei}. However, the approach taken in the pgfkeys packages allows for more flexibility. For
instance, assume that you have a key that expects a hvaluei of the form “htexti+hmore texti” and wishes to
store htexti and hmore texti in two different macros. This can be achieved as follows:
\a is hello, \b is world.
\def\mystore#1+#2\pgfeov{\def\a{#1}\def\b{#2}}
\pgfkeyslet{/my key/.@cmd}{\mystore}
\pgfkeys{/my key=hello+world}
|\a| is \a, |\b| is \b.
Naturally, defining the code to be stored in a key in the above manner is too awkward. The following
commands simplify things a bit, but the usual manner of setting up code for a key is to use one of the
handlers described in Section 82.4.3.
\pgfkeysdef{hkeyi}{hcodei}
This command temporarily defines a TEX-macro with the argument list #1\pgfeov and then lets
hkeyi/.@cmd be equal to this macro. The net effect of all this is that you have then set up code for the
key hkeyi so that when you write \pgfkeys{hkeyi=hvaluei}, then the hcodei is executed with all occurrences of #1 in hcodei being replaced by hvaluei. (This behaviour is quite similar to the \define@key
command of keyval and xkeyval).
hello, hello.
\pgfkeysdef{/my key}{#1, #1.}
\pgfkeys{/my key=hello}
\pgfkeysedef{hkeyi}{hcodei}
This command works like \pgfkeysdef, but it uses \edef rather than \def when defining the key
macro. If you do not know the difference between the two, then you will not need this command; and
if you know the difference, then you will know when you need this command.
\pgfkeysdefnargs{hkeyi}{hargument counti}{hcodei}
This command works like \pgfkeysdef, but it allows you to provide an arbitrary hargument counti
between 0 and 9 (inclusive).
\a is ‘hello’, \b is ‘world’.
\pgfkeysdefnargs{/my key}{2}{\def\a{#1}\def\b{#2}}
\pgfkeys{/my key=
{hello}
{world}}
|\a| is ‘\a’, |\b| is ‘\b’.
The resulting key will expect exactly {hargument counti} arguments.
\pgfkeysedefnargs{hkeyi}{hargument counti}{hcodei}
The \edef version of \pgfkeysdefnargs.
\pgfkeysdefargs{hkeyi}{hargument patterni}{hcodei}
This command works like \pgfkeysdefnargs, but it allows you to provide an arbitrary hargument
patterni rather than just a number of arguments.
\a is hello, \b is world.
\pgfkeysdefargs{/my key}{#1+#2}{\def\a{#1}\def\b{#2}}
\pgfkeys{/my key=hello+world}
|\a| is \a, |\b| is \b.
Note that \pgfkeysdefnargs is better when it comes to simple argument counts 12 .
\pgfkeysedefargs{hkeyi}{hargument patterni}{hcodei}
The \edef version of \pgfkeysdefargs.
12 When
the resulting keys are used, the defnargs variant allows spaces between arguments whereas the defargs variant does
not; it considers the spaces as part of the argument.
881
82.3.4
Keys That Store Values
Let us continue with what happens when \pgfkeys processes the current key and the subkey hkeyi/.@cmd is
not defined. Then it is checked whether the hkeyi itself exists (has been previously assigned a value using, for
instance, \pgfkeyssetvalue). In this case, the tokens stored in hkeyi are replaced by hvaluei and \pgfkeys
proceeds with the next key in the hkey listi.
82.3.5
Keys That Are Handled
If neither the hkeyi itself nor the subkey hkeyi/.@cmd are defined, then the hkeyi cannot be processed “all
by itself.” Rather, a hhandler i is needed for this key. Most of the power of pgfkeys comes from the proper
use of such handlers.
Recall that the hkeyi is always a full key (if it was not originally, it has already been upgraded at this
point to a full key). It decomposed into two parts:
1. The hpathi of hkeyi (everything before the last slash) is stored in the macro \pgfkeyscurrentpath.
2. The hnamei of hkeyi (everything after the last slash) is stored in the macro \pgfkeyscurrentname.
It is recommended (but not necessary) that the name of a handler starts with a dot (but not with .@),
so that they are easy to detect for the reader.
(For efficiency reasons, these two macros are only set up at this point; so when code is executed for a
key in the “usual” manner then these macros are not set up.)
The \pgfkeys command now checks whether the key /handlers/hnamei/.@cmd exists. If so, it should
store a command and this command is executed exactly in the same manner as described in Section 82.3.3.
Thus, this code gets the hvaluei that was originally intended for hkeyi as its argument, followed by \pgfeov.
It is the job of the handlers to do something useful with the hvaluei.
For an example, let us write a handler that will output the value stored in a key to the log file. We
call this handler /.print to log. The idea is that when someone tries to use the key /my key/.print to
log, then this key will not be defined and the handler gets executed. The handler will then have access to
the path-part of the key, which is /my key, via the macro \pgfkeyscurrentpath. It can then lookup which
value is stored in this key and print it.
\pgfkeysdef{/handlers/.print to log}
{%
\pgfkeysgetvalue{\pgfkeyscurrentpath}{\temp}
\writetolog{\temp}
}
\pgfkeyssetvalue{/my key}{Hi!}
...
\pgfkeys{/my key/.print to log}
The above code will print Hi! in the log, provided the macro \writetolog is set up appropriately.
For a more interesting handler, let us program a handler that will set up a key so that when the key is
used, some code is executed. This code is given as hvaluei. All the handler must do is to call \pgfkeysdef
for the path of the key (which misses the handler’s name) and assign the parameter value to it.
(hallo)
\pgfkeysdef{/handlers/.my code}{\pgfkeysdef{\pgfkeyscurrentpath}{#1}}
\pgfkeys{/my key/.my code=(#1)}
\pgfkeys{/my key=hallo}
There are some parameters for handled keys which prove to be useful in some (possibly rare) special
cases:
/handler config=all|only existing|full or existing
(no default, initially all)
Changes the initial configuration how key handlers will be used.
This configuration is for advanced users and rarely necessary.
all The preconfigured setting all works as described above and imposes no restriction on the key
setting process.
only existing The value only existing modifies the algorithm for handled keys as follows: a handler
hkey namei/.hhandler i will be executed only if hkey namei is either a key which stores its value
directly or a command key for which /.@cmd exists. If hkey namei does not exist already, the
882
complete string hkey namei/.hhandler i is considered to be an unknown key and the procedure
described in the next section applies (for the path of hkey namei).
Initial definition.Re-Definition.Unknown key ‘’.
% Define a test key and error handlers:
\pgfkeys{/the/key/.code={Initial definition. }}
\pgfkeys{/handlers/.unknown/.code={Unknown key ‘\pgfkeyscurrentkey’. }}
% calling the test key yields ’Initial definition. ’:
\pgfkeys{/the/key}
% Change configuration:
\pgfkeys{/handler config=only existing}
% allowed: key *re*-definition:
\pgfkeys{/the/key/.code={Re-Definition. }}
% calling the key yields ’Re-Definition. ’:
\pgfkeys{/the/key}
% not allowed: definition of new keys:
% this checks for ’/the/other key/.unknown’
% and ’/handlers/.unknown’
% and yields finally
% ’Unknown key ‘/the/other key/.code‘’
\pgfkeys{/the/other key/.code={New definition. }}
It is necessary to exclude some key handlers from this procedure. Altogether, the detailed procedure
is as follows:
1. If a handled key like /a path/a key/.a handler=value is encountered, it is checked whether
the handler should be invoked. This is the case if
• An exception from only existing for this key exists (see below),
• The key /a path/a key exists already – either directly as storage key or with the .@cmd
suffix.
2. If the check passes, everything works as before.
3. If the check fails, the complete key will be considered to be unknown. In that case, the handling
of unknown keys as described in the next section applies. There, the current key path will be
set to /a path and the current key’s name to key/.a handler.
A consequence of this configuration is to provide more meaningful processing of handled keys if a
search path for keys is in effect, see section 82.3.6 for an example.
full or existing Finally, the choice full or existing is a variant of only existing: it works in
the same way for keys which do not have a full key path. For example, the style
\pgfkeys{/my path/.cd,key/.style={. . . }}
can only be redefined: it doesn’t have a full path, so the only existing mechanism applies. But
the style
\pgfkeys{/my path/key/.style={. . . }}
will still work. This allows users to override the only existing feature if they know what they’re
doing (and provide full key paths).
/handler config/only existing/add exception={hkey handler namei}
(no default)
Allows to add exceptions to the /handler config=only existing feature. Initially exceptions for the
key handlers /.cd, /.try, /.retry, /.lastretry and /.unknown are defined. The value {hkey handler
namei} should be the name of a key handler.
82.3.6
Keys That Are Unknown
For some keys, neither the key, nor its .@cmd subkey nor a handler is defined. In this case, it is checked
whether the key hcurrent pathi/.unknown/.@cmd exists. Thus, when you try to use the key /tikz/strange,
then it is checked whether /tikz/.unknown/.@cmd exists. If this key exists (which it does), it is executed.
This code can then try to make sense of the key. For instance, the handler for Tik Z will try to interpret the
key’s name as a color or as an arrow specification or as a pgf option.
883
You can set up unknown key handlers for your own keys by simply setting the code of the key hmy path
prefix i/.unknown. This also allows you to set up “search paths.” The idea is that you would like keys to be
searched not only in a single default path, but in several. Suppose, for instance, that you would like keys to
be searched for in /a, /b, and /b/c. We set up a key /my search path for this:
\pgfkeys{/my search path/.unknown/.code=
{%
\let\searchname=\pgfkeyscurrentname%
\pgfkeysalso{%
/a/\searchname/.try=#1,
/b/\searchname/.retry=#1,
/b/c/\searchname/.retry=#1%
}%
}%
}
\pgfkeys{/my search path/.cd,foo,bar}
In the above code, foo and bar will be searched for in the three directories /a, /b, and /b/c. Before you
start implementing search paths using this pattern, consider the /.search also handler discussed below.
If the key hcurrent pathi/.unknown/.@cmd does not exist, the handler /handlers/.unknown is invoked
instead, which is always defined and which prints an error message by default.
82.3.7
Search Paths And Handled Keys
There is one special case which occurs in the search path example above. What happens if we want to change
a style? For example,
\pgfkeys{/my search path/.cd,custom/.style={variables}}
could mean a style in /my search path/, /a/, /b/ or even /b/c/!
Due to the rules for handled keys, the answer is /my search path/custom/.style={variables}.
It may be useful to modify this default behavior. One useful thing would be to search for existing
styles named custom and redefine them. For example, if a style /b/custom exists, the assignment custom/.style={variables} should probably redefine /b/custom instead of /my search path/custom. This
can be done using handler config:
This is ‘/b/custom’.
This is ‘/b/custom’.Modified.
\pgfkeys{/my search path/.unknown/.code=
{%
\let\searchname=\pgfkeyscurrentname%
\pgfkeysalso{%
/a/\searchname/.try=#1,
/b/\searchname/.retry=#1,
/b/c/\searchname/.retry=#1%
}%
}%
}
% Let’s define /b/custom here:
\pgfkeys{/b/custom/.code={This is ‘\pgfkeyscurrentkey’. }}
% Reconfigure treatment of key handlers:
\pgfkeys{/handler config=only existing}
% The search path procedure will find /b/custom
% -> leads to This is ‘/b/custom’
\pgfkeys{/my search path/.cd,custom}
% Due to the reconfiguration, this will find /b/custom instead of
% defining /my search path/custom:
\pgfkeys{/my search path/.cd,custom/.append code={Modified. }}
% So using the search path, we again find /b/custom which
% leads to This is ‘/b/custom’ Modified
\pgfkeys{/my search path/.cd,custom}
A slightly different approach to search paths can be realized using the /.search also key handler, see
below.
884
82.4
Key Handlers
We now describe which key handlers are defined by default. You can also define new ones as described in
Section 82.3.5.
82.4.1
Handlers for Path Management
Key handler hkeyi/.cd
This handler causes the default path to be set to hkeyi. Note that the default path is reset at the
beginning of each call to \pgfkeys to be equal to /.
Example: \pgfkeys{/tikz/.cd,...}
Key handler hkeyi/.is family
This handler sets up things such that when hkeyi is executed, then the current path is set to hkeyi. A
typical use is the following:
\pgfkeys{/tikz/.is family}
\pgfkeys{tikz,line width=1cm}
The effect of this handler is the same as if you had written hkeyi/.style=hkeyi/.cd, only the code
produced by the /.is family handler is quicker.
82.4.2
Setting Defaults
Key handler hkeyi/.default=hvaluei
Sets the default value of hkeyi to hvaluei. This means that whenever no value is provided in a call to
\pgfkeys, then this hvaluei will be used instead.
Example: \pgfkeys{/width/.default=1cm}
Key handler hkeyi/.value required
This handler causes the error message key /erros/value required to be issued whenever the hkeyi is
used without a value.
Example: \pgfkeys{/width/.value required}
Key handler hkeyi/.value forbidden
This handler causes the error message key /erros/value forbidden to be issued whenever the hkeyi
is used with a value.
This handler works be adding code to the code of the key. This means that you have to define the key
first before you can use this handler.
\pgfkeys{/my key/.code=I do not want an argument!}
\pgfkeys{/my key/.value forbidden}
\pgfkeys{/my key}
% Ok
\pgfkeys{/my key=foo} % Error
82.4.3
Defining Key Codes
A number of handlers exist for defining the code of keys.
Key handler hkeyi/.code=hcodei
This handler executes \pgfkeysdef with the parameters hkeyi and hcodei. This means that, afterwards,
whenever the hkeyi is used, the hcodei gets executed. More precisely, when hkeyi=hvaluei is encountered
in a key list, hcodei is executed with any occurrence of #1 replaced by hvaluei. As always, if no hvaluei
is given, the default value is used, if defined, or the special value \pgfkeysnovalue.
It is permissible that hcodei calls the command \pgfkeys. It is also permissible the hcodei calls the
command \pgfkeysalso, which is useful for styles, see below.
885
\pgfkeys{/par indent/.code={\parindent=#1},/par indent/.default=2em}
\pgfkeys{/par indent=1cm}
...
\pgfkeys{/par indent}
Key handler hkeyi/.ecode=hcodei
This handler works like /.code, only the command \pgfkeysedef is used.
Key handler hkeyi/.code 2 args=hcodei
This handler works like /.code, only two arguments rather than one are expected when the hcodei is
executed. This means that when hkeyi=hvaluei is encountered in a key list, the hvaluei should consist
of two arguments. For instance, hvaluei could be {first}{second}. Then hcodei is executed with any
occurrence of #1 replaced first and any occurrence of #2 replaced by second.
\pgfkeys{/page size/.code 2 args={\paperheight=#2\paperwidth=#1}}
\pgfkeys{/page size={30cm}{20cm}}
The second argument is optional: if it is not provided, it will be the empty string.
Because of the special way the hvaluei is parsed, if you set hvaluei to, for instance, first (without any
braces), then #1 will be set to f and #2 will be set to irst.
Key handler hkeyi/.ecode 2 args=hcodei
This handler works like /.code 2 args, only an \edef is used rather than a \def to define the macro.
Key handler hkeyi/.code n args={hargument counti}{hcodei}
This handler also works like /.code, but you can now specify a number of arguments between 0 and 9
(inclusive).
First=‘A’, Second=‘B’
\pgfkeys{/a key/.code n args={2}{First=‘#1’, Second=‘#2’}}
\pgfkeys{/a key={A}{B}}
In contrast to /.code 2 args, there must be exactly hargument counti arguments, not more and not
less and these arguments should be properly delimited.
Key handler hkeyi/.ecode n args={hargument counti}{hcodei}
This handler works like /.code n args, only an \edef is used rather than a \def to define the macro.
Key handler hkeyi/.code args={hargument patterni}{hcodei}
This handler is the most flexible way to define a /.code key: you can now specify an arbitrary hargument
patterni. Such a pattern is a usual TEX macro pattern. For instance, suppose hargument patterni is
(#1/#2) and hkeyi=hvaluei is encountered in a key list with hvaluei being (first/second). Then hcodei
is executed with any occurrence of #1 replaced first and any occurrence of #2 replaced by second.
So, the actual hvaluei is matched against the hargument patterni in the standard TEX way.
\pgfkeys{/page size/.code args={#1 and #2}{\paperheight=#2\paperwidth=#1}}
\pgfkeys{/page size=30cm and 20cm}
Note that /.code n args should be preferred in case you need just a number of arguments (when the
resulting keys are used, /.code n args gobbles spaces between the arguments whereas /.code args
considers spaces to be part of the argument).
Key handler hkeyi/.ecode args={hargument patterni}{hcodei}
This handler works like /.code args, only an \edef is used rather than a \def to define the macro.
There are also handlers for modifying existing keys.
Key handler hkeyi/.add code={hprefix codei}{happend codei}
This handler adds code to an existing key. The hprefix codei is added to the code stored in hkeyi/.@cmd
at the beginning, the happend codei is added to this code at the end. Either can be empty. The argument
list of hcodei cannot be changed using this handler. Note that both hprefix codei and happend codei may
contain parameters like #2.
886
\pgfkeys{/par indent/.code={\parindent=#1}}
\newdimen\myparindent
\pgfkeys{/par indent/.add code={}{\myparindent=#1}}
...
\pgfkeys{/par indent=1cm} % This will set both \parindent and
% \myparindent to 1cm
Key handler hkeyi/.prefix code=hprefix codei
This handler is a shortcut for hkeyi/.add code={hprefix codei}{}. That is, this handler adds the hprefix
codei at the beginning of the code stored in hkeyi/.@cmd.
Key handler hkeyi/.append code=happend codei
This handler is a shortcut for hkeyi/.add code={}{happend codei}{}.
82.4.4
Defining Styles
The following handlers allow you to define styles. A style is a key list that is processed whenever the style is
given as a key in a key list. Thus, a style “stands for” a certain key value list. Styles can be parameterized
just like normal code.
Key handler hkeyi/.style=hkey listi
This handler sets things up so that whenever hkeyi=hvaluei is encountered in a key list, then the hkey
listi, with every occurrence of #1 replaced by hvaluei, is processed instead. As always, if no hvaluei is
given, the default value is used, if defined, or the special value \pgfkeysnovalue.
You can achieve the same effect by writing hkeyi/.code=\pgfkeysalso{hkey listi}. This means, in
particular, that the code of a key could also first execute some normal code and only then process some
further keys.
\pgfkeys{/par indent/.code={\parindent=#1}}
\pgfkeys{/no indent/.style={/par indent=0pt}}
\pgfkeys{/normal indent/.style={/par indent=2em}}
\pgfkeys{/no indent}
...
\pgfkeys{/normal indent}
The following example shows a parameterized style “in action”.
red box
blue box
\begin{tikzpicture}[outline/.style={draw=#1,fill=#1!20}]
\node [outline=red]
{red box};
\node [outline=blue] at (0,-1) {blue box};
\end{tikzpicture}
Key handler hkeyi/.estyle=hkey listi
This handler works like /.style, only the hcodei is set using \edef rather than \def. Thus, all macros
in the hcodei are expanded prior to saving the style.
For styles the corresponding handlers as for normal code exist:
Key handler hkeyi/.style 2 args=hkey listi
This handler works like /.code 2 args, only for styles. Thus, the hkey listi may contain occurrences
of both #1 and #2 and when the style is used, two parameters must be given as hvaluei.
\pgfkeys{/paper height/.code={\paperheight=#1},/paper width/.code={\paperwidth=#1}}
\pgfkeys{/page size/.style 2 args={/paper height=#1,/paper width=#2}}
\pgfkeys{/page size={30cm}{20cm}}
Key handler hkeyi/.estyle 2 args=hkey listi
This handler works like /.style 2 args, only an \edef is used rather than a \def to define the macro.
Key handler hkeyi/.style args={hargument patterni}{hkey listi}
This handler works like /.code args, only for styles.
887
Key handler hkeyi/.estyle args={hargument patterni}{hcodei}
This handler works like /.ecode args, only for styles.
Key handler hkeyi/.style n args={hargument counti}hkey listi
This handler works like /.code n args, only for styles. Here, hkey listi may depend on all hargument
counti parameters.
Key handler hkeyi/.add style={hprefix key listi}{happend key listi}
This handler works like /.add code, only for styles. However, it is permissible to add styles to keys
that have previously been set using /.code. (It is also permissible to add normal hcodei to a key that
has previously been set using /.style). When you add a style to a key that was previously set using
/.code, the following happens: When hkeyi is processed, the hprefix key listi will be processed first,
then the hcodei that was previously stored in hkeyi/.@cmd, and then the keys in happend key listi are
processed.
\pgfkeys{/par indent/.code={\parindent=#1}}
\pgfkeys{/par indent/.add style={}{/my key=#1}}
...
\pgfkeys{/par indent=1cm} % This will set \parindent and
% then execute /my key=#1
Key handler hkeyi/.prefix style=hprefix key listi
Works like /.add style, but only for the prefix key list.
Key handler hkeyi/.append style=happend key listi
Works like /.add style, but only for the append key list.
82.4.5
Defining Value-, Macro-, If- and Choice-Keys
For some keys, the code that should be executed for them is rather “specialized.” For instance, it happens
often that the code for a key just sets a certain TEX-if to true or false. For these cases, predefined handlers
make it easier to install the necessary code.
However, we start with some handlers that are used to manage the value that is directly stored in a key.
Key handler hkeyi/.initial=hvaluei
This handler sets the value of hkeyi to hvaluei. Note that no subkeys are involved. After this handler
has been used, by the rules governing keys, you can subsequently change the value of the hkeyi by just
writing hkeyi=hvaluei. Thus, this handler is used to set the initial value of key.
\pgfkeys{/my key/.initial=red}
% "/my key" now stores the value "red"
\pgfkeys{/my key=blue}
% "/my key" now stores the value "blue"
Note that with this configuration, writing \pgfkeys{/my key} will not have the effect you might expect (namely that blue is inserted into the main text). Rather, /my key will be promoted to /my
key=\pgfkeysnovalue and, thus, \pgfkeysnovalue will be stored in /my key.
To retrieve the value stored in a key, the handler /.get is used.
Key handler hkeyi/.get=hmacroi
Executes a \let command so that hmacroi contains the contents stored in hkeyi.
blue
\pgfkeys{/my key/.initial=red}
\pgfkeys{/my key=blue}
\pgfkeys{/my key/.get=\mymacro}
\mymacro
Key handler hkeyi/.add={hprefix valuei}{happend valuei}
Adds the hprefix valuei and the beginning and the happend valuei at the end of the value stored in hkeyi.
888
Key handler hkeyi/.prefix={hprefix valuei}
Adds the hprefix valuei and the beginning of the value stored in hkeyi.
Key handler hkeyi/.append={happend valuei}
Adds the happend valuei at the end of the value stored in hkeyi.
Key handler hkeyi/.link=hanother keyi
Stores the value \pgfkeysvalueof{hanother keyi} in the hkeyi. The idea is that when you expand the
hkeyi, the value of hanother keyi is expanded instead. This corresponds loosely to the notion of soft
links in Unix, hence the name.
The next handler is useful for the common situation where hkeyi=hvaluei should cause the hvaluei to be
stored in some macro. Note that, typically, you could just as well store the value in the key itself.
Key handler hkeyi/.store in=hmacroi
This handler has the following effect: When you write hkeyi=hvaluei, the code \defhmacroi{hvaluei} is
executed. Thus, the given value is “stored” in the hmacroi.
Hello Gruffalo!
\pgfkeys{/text/.store in=\mytext}
\def\a{world}
\pgfkeys{/text=Hello \a!}
\def\a{Gruffalo}
\mytext
Key handler hkeyi/.estore in=hmacroi
This handler is similar to /.store in, only the code \edefhmacroi{hvaluei} is used. Thus, the macroexpanded version of hvaluei is stored in the hmacroi.
Hello world!
\pgfkeys{/text/.estore in=\mytext}
\def\a{world}
\pgfkeys{/text=Hello \a!}
\def\a{Gruffalo}
\mytext
In another common situation a key is used to set a TEX-if to true or false.
Key handler hkeyi/.is if=hTEX-if namei
This handler has the following effect: When you write hkeyi=hvaluei, it is first checked that hvaluei
is true or false (the default is true if no hvaluei is given). If this is not the case, the error key
/errors/boolean expected is executed. Otherwise, the code \hTEX-if nameihvaluei is executed, which
sets the TEX-if accordingly.
Round?
\newif\iftheworldisflat
\pgfkeys{/flat world/.is if=theworldisflat}
\pgfkeys{/flat world=false}
\iftheworldisflat
Flat
\else
Round?
\fi
The next handler deals with the problem when a hkeyi=hvaluei makes sense only for a small set of possible
hvalueis. For instance, the line cap can only be rounded or rect or butt, but nothing else. For this situation
the following handler is useful.
Key handler hkeyi/.is choice
This handler sets things up so that writing hkeyi=hvaluei will cause the subkey hkeyi/hvaluei to be
executed. So, each of the different possible choices should be given by a subkey of hkeyi.
889
\pgfkeys{/line cap/.is choice}
\pgfkeys{/line cap/round/.style={\pgfsetbuttcap}}
\pgfkeys{/line cap/butt/.style={\pgfsetroundcap}}
\pgfkeys{/line cap/rect/.style={\pgfsetrectcap}}
\pgfkeys{/line cap/rectangle/.style={/line cap=rect}}
...
\draw [/line cap=butt] ...
If the subkey hkeyi/hvaluei does not exist, the error key /errors/unknown choice value is executed.
82.4.6
Expanded and Multiple Values
When you write hkeyi=hvaluei, you usually wish to use the hvaluei “as is.” Indeed, great care is taken to
ensure that you can even use things like #1 or unbalanced TEX-ifs inside hvaluei. However, sometimes you
want the hvaluei to be expanded before it is used. For instance, hvaluei might be a macro name like \mymacro
and you do not want \mymacro to be used as the macro, but rather the contents of \mymacro. Thus, instead
of using hvaluei, you wish to use whatever hvaluei expands to. Instead of using some fancy \expandafter
hackery, you can use the following handlers:
Key handler hkeyi/.expand once=hvaluei
This handler expands hvaluei once (more precisely, it executes an \expandafter command on the first
token of hvaluei) and then process the resulting hresulti as if you had written hkeyi=hresulti. Note that
if hkeyi contains a handler itself, this handler will be called normally.
Key
Key
Key
Key
1:
2:
3:
4:
\c
\b
\a
bottom
\def\a{bottom}
\def\b{\a}
\def\c{\b}
\pgfkeys{/key1/.initial=\c}
\pgfkeys{/key2/.initial/.expand once=\c}
\pgfkeys{/key3/.initial/.expand twice=\c}
\pgfkeys{/key4/.initial/.expanded=\c}
\def\a{{\ttfamily\string\a}}
\def\b{{\ttfamily\string\b}}
\def\c{{\ttfamily\string\c}}
\begin{tabular}{ll}
Key 1:& \pgfkeys{/key1} \\
Key 2:& \pgfkeys{/key2} \\
Key 3:& \pgfkeys{/key3} \\
Key 4:& \pgfkeys{/key4}
\end{tabular}
Key handler hkeyi/.expand twice=hvaluei
This handler works like saying hkeyi/.expand once/.expand once=hvaluei.
Key handler hkeyi/.expanded=hvaluei
This handler will completely expand hvaluei (using \edef) before processing hkeyi=hresulti.
Key handler hkeyi/.list=hcomma-separated list of valuesi
This handler causes the key to be used repeatedly, namely once for every element of the list of values.
Note that the list of values should typically be surrounded by braces since, otherwise, TEX will not be
able to tell whether a comma starts a new key or a new value.
The hlist of valuesi is processed using the \foreach statement, so you can use the ... notation.
(a)(b)(0)(1)(2)(3)(4)(5)
82.4.7
\pgfkeys{/foo/.code=(#1)}
\pgfkeys{/foo/.list={a,b,0,1,...,5}}
Handlers for Forwarding
Key handler hkeyi/.forward to=hanother keyi
This handler causes the hkeyi to “forward” its argument to hanother keyi. When the hkeyi is used, its
normal code will be executed first. Then, the value is (additionally) passed to hanother keyi. If the
890
hkeyi has not yet been defined prior to the use of .forward to, it will be defined then (and do nothing
by itself, expect for forwarding it to hkey namei). The hanother keyi must be a fully qualified key
name.
(b:1)(a:1) (a:2)
\pgfkeys{
/a/.code=(a:#1),
/b/.code=(b:#1),
/b/.forward to=/a,
/c/.forward to=/a
}
\pgfkeys{/b=1} \pgfkeys{/c=2}
Key handler hkeyi/.search also={hpath listi}
A style which installs a /.unknown handler into hkeyi. This /.unknown handler will then search for
unknown keys in every path provided in {hpath listi}.
Invoking /secondary path/option with ‘value’
% define a key:
\pgfkeys{/secondary path/option/.code={Invoking /secondary path/option with ‘#1’}}
% set up a search path:
\pgfkeys{/main path/.search also={/secondary path}}
% try searching for ‘option=value’ in ’/main path’:
% -> this finds ‘/secondary path/option’!
\pgfkeys{/main path/.cd,option=value}
The /.search also handler follows the strategy
1. If a user provides a fully qualified key which could not be found, for example the full string /main
path/option, it assume that the user knew what she is doing – and does not continue searching
for an option in {hpath listi}.
2. If a user provides only the key’s name, for example option and option cannot be found in the
current default path (which is /main path in our example above), the current default path is set to
the next element in {hpath listi} (which is /secondary path here) and \pgfkeys will be restarted.
This will be iterated until either a match has been found or all elements in {hpath listi} have been
tested.
3. If all elements in {hpath listi} have been checked and the key is still unknown, the fall-back handler
/handlers/.unknown will be invoked.
Invoking /secondary path/option with ‘value’
% define a key:
\pgfkeys{/secondary path/option/.code={Invoking /secondary path/option with ‘#1’}}
% set up a search path:
\pgfkeys{/main path/.search also={/secondary path}}
% try searching for ‘option=value’ in ’/main path’:
% -> this finds ‘/secondary path/option’!
\pgfkeys{/main path/.cd,option=value}
% negative example:
% try searching for fully qualified key /main path/option.
% This won’t be handled by .search also.
\pgfkeys{/handlers/.unknown/.code={Found unknown option \pgfkeyscurrentkeyRAW={#1}!}}%
\pgfkeys{/main path/.cd,/main path/option=value}
Please note that the strategy of /.search also is different from the first example provided in section 82.3.6 “Unknown Keys” because /.search also only applies to keys that are not fully qualified.
For those who are familiar with \pgfkeys, the actual implementation of /.search also might be
interesting:
1. \pgfkeys{/path/.search also={/tikz}} is equivalent to
891
\pgfkeys{/path/.unknown/.code={%
\ifpgfkeysaddeddefaultpath
% only process keys for which no full path has been
% provided:
\pgfkeyssuccessfalse
\let\pgfkeys@searchalso@name =\pgfkeyscurrentkeyRAW
\ifpgfkeyssuccess
\else
% search with /tikz as default path:
\pgfqkeys{/tikz}{\pgfkeys@searchalso@name={#1}}%
\fi
\else
\def\pgfutilnext{\pgfkeysvalueof {/handlers/.unknown/.@cmd}#1\pgfeov}%
\pgfutilnext
\fi
}
}
2. \pgfkeys{/path/.search also={/tikz,/pgf}} is equivalent to
\pgfkeys{/path/.unknown/.code={%
\ifpgfkeysaddeddefaultpath
\pgfkeyssuccessfalse
\let\pgfkeys@searchalso@name=\pgfkeyscurrentkeyRAW
\ifpgfkeyssuccess
\else
% step 1: search in /tikz with .try:
\pgfqkeys{/tikz}{\pgfkeys@searchalso@name/.try={#1}}%
\fi
\ifpgfkeyssuccess
\else
% step 2: search in /pgf (without .try!):
\pgfqkeys{/pgf}{\pgfkeys@searchalso@name={#1}}%
\fi
\else
\def\pgfutilnext{\pgfkeysvalueof {/handlers/.unknown/.@cmd}#1\pgfeov}%
\pgfutilnext
\fi
}
}
To also enable searching for styles (or other handled keys), consider changing the configuration for
handled keys to /hander config=full or existing when you use /.search also, that is, use
\pgfkeys{
/main path/.search also={/secondary path},
/handler config=full or existing}
82.4.8
Handlers for Testing Keys
Key handler hkeyi/.try=hvaluei
This handler causes the same things to be done as if hkeyi=hvaluei had been written instead. However,
if neither hkeyi/.@cmd nor the key itself is defined, no handlers will be called. Instead, the execution of
the key just stops. Thus, this handler will “try” to use the key, but no further action is taken when the
key is not defined.
The TEX-if \ifpgfkeyssuccess will be set according to whether the hkeyi was successfully executed
or not.
(a:hallo)(b:welt)
\pgfkeys{/a/.code=(a:#1)}
\pgfkeys{/b/.code=(b:#1)}
\pgfkeys{/x/.try=hmm,/a/.try=hallo,/b/.try=welt}
Key handler hkeyi/.retry=hvaluei
This handler works just like /.try, only it will not do anything if \ifpgfkeyssuccess is false. Thus,
this handler will only retry to set a key if “the last attempt failed”.
892
(a:hallo)
\pgfkeys{/a/.code=(a:#1)}
\pgfkeys{/b/.code=(b:#1)}
\pgfkeys{/x/.try=hmm,/a/.retry=hallo,/b/.retry=welt}
Key handler hkeyi/.lastretry=hvaluei
This handler works like /.retry, only it will invoke the usual handlers for unknowns keys if
\ifpgfkeyssuccess is false. Thus, this handler will only try to set a key if “the last attempt failed”.
Furthermore, this here is the last such attempt.
82.4.9
Handlers for Key Inspection
Key handler hkeyi/.show value
This handler executes a \show command on the value stored in hkeyi. This is useful mostly for debugging.
Example: \pgfkeys{/my/obscure key/.show value}
Key handler hkeyi/.show code
This handler executes a \show command on the code stored in hkeyi/.@cmd. This is useful mostly for
debugging.
Example: \pgfkeys{/my/obscure key/.show code}
The following key is not a handler, but it also commonly used for inspecting things:
(no default)
/utils/exec=hcodei
This key will simply execute the given hcodei.
Example: \pgfkeys{some key=some value,/utils/exec=\show\hallo,obscure key=obscure}
82.5
Error Keys
In certain situations errors can occur, like using an undefined key. In these situations error keys are executed.
They should store a macro that gets two arguments: The first is the offending key (possibly only after macro
expansion), the second is the value that was passed as a parameter (also possibly only after macro expansion).
Currently, error keys are simply executed. In the future it might be a good idea to have different subkeys
that are executed depending on the language currently set so that users get a localized error message.
/errors/value required={hoffending keyi}{hvaluei}
(no default)
This key is executed whenever an hoffending keyi is used without a value when a value is actually
required.
/errors/value forbidden={hoffending keyi}{hvaluei}
(no default)
This key is executed whenever a key is used with a value when a value is actually forbidden.
/errors/boolean expected={hoffending keyi}{hvaluei}
(no default)
This key is executed whenever a key set up using /.is if gets called with a hvaluei other than true
or false.
/errors/unknown choice value={hoffending keyi}{hvaluei}
(no default)
This key is executed whenever a choice is used as a hvaluei for a key set up using the /.is choice
handler that is not defined.
/errors/unknown key={hoffending keyi}{hvaluei}
(no default)
This key is executed whenever a key is unknown and no specific /.unknown handler is found.
893
82.6
Key Filtering
An extension by Christian Feuersänger
Normally, a call to \pgfkeys sets all keys provided in its argument list. This is usually what users expect
it to do. However, implementations of different packages or pgf-libraries may need more control over the
key setting procedure: library A may want to set its options directly and communicate all remaining ones
to library B.
This section describes key filtering methods of pgf, including options for family groupings. If you merely
want to use pgf (or its libraries), you can skip this section. It is addressed to package (or library) authors.
82.6.1
Starting With An Example
Users of xkeyval are familiar with the concept of key families: keys belong to groups and those keys can be
‘filtered’ out of other options. pgf supports family groupings and more abstract key selection mechanism
with \pgfkeysfiltered, a variant of \pgfkeys. Suppose we have the example key grouping
\pgfkeys{
/my group/A1/.code=(A1:#1),
/my group/A2/.code=(A2:#1),
/my group/A3/.code=(A3:#1),
/my group/B/.code=(B:#1),
/my group/C/.code=(B:#1),
}
and we want to set options A1, A2 and A3 only. A call to \pgfkeys yields
(A1:a1)(A2:a2)(B:b)(B:c)
\pgfkeys{/my group/A1=a1, /my group/A2=a2, /my group/B=b,
/my group/C=c}
because all those command option are processed consecutively.
Now, let’s define a family named A which contains A1, A2 and A3 and set only family members of A. We
prepare our key settings with
\pgfkeys{
/my group/A/.is family,
/my group/A1/.belongs to family=/my group/A,
/my group/A2/.belongs to family=/my group/A,
/my group/A3/.belongs to family=/my group/A,
}
and
\pgfkeys{/pgf/key filters/active families/.install key filter}
After this preparation, we can use \pgfkeysfiltered with
(A1:a1)(A2:a2)
\pgfkeys{/my group/A/.activate family}
\pgfkeysfiltered{/my group/A1=a1, /my group/A2=a2,
/my group/B=b, /my group/C=c}
or
(A1:a1)(A2:a2)(A3:a3)
\pgfkeys{/my group/A/.activate family}
\pgfkeysfiltered{/my group/A1=a1, /my group/A2=a2,
/my group/B=b, /my group/C=c, /tikz/color=blue, /my group/A3=a3}
to set only keys which belong to an ‘active’ family – in our case, only family A was active, so the remaining
options have not been processed. The family processing is quite fast and allows an arbitrary number of
active key families.
Unprocessed options can be collected into a macro (similar to xkeyval’s \xkv@rm), discarded or handled
manually. The details of key selection and family declaration are described in the following sections.
82.6.2
Setting Filters
The command \pgfkeysfiltered is the main tool to process only selected options. It works as follows.
\pgfkeysfiltered{hkey-value-listi}
Processes all options in exactly the same way as \pgfkeys{hkey-value-listi}, but a key filter is considered
as soon as key identification is complete.
894
The key filter tells \pgfkeysfiltered whether it should continue to apply the current option (return
value is ‘true’) or whether something different shall be done (filter returns ‘false’).
There is exactly one key filter in effect, and it is installed by the .install key filter handler or by
\pgfkeysinstallkeyfilter.
If the key filter returns ‘false’, a unique key filter handler gets control. This handler is installed by the
.install key filter handler method and has access to the key’s full name, value and (possibly)
path.
Key filtering applies to any (possibly nested) call to \pgfkeys, \pgfkeysalso, \pgfqkeys and
\pgfqkeysalso during the evaluation of {hkey-value-listi}. It does not apply to routines like
\pgfkeyssetvalue or \pgfkeysgetvalue. Furthermore, keys belonging to /errors are always processed. Key filtering routines can’t be nested: you can’t combine different key filters automatically.
\pgfqkeysfiltered{hdefault-pathi}{hkey-value-listi}
A variant of \pgfkeysfiltered which uses the ‘quick’ search path setting. It is the \pgfqkeys variant
of \pgfkeysfiltered, see the documentation for \pgfqkeys for more details.
\pgfkeysalsofrom{hmacroi}
A variant of \pgfkeysalso which loads its key list from {hmacroi}.
It is useful in conjunction with the /pgf/key filter handlers/append filtered to=hmacroi handler.
The following example uses the same settings as in the intro section 82.6.1.
(A1:a1)(A2:a2)(A3:a3)Remaining: ‘/my group/B=b,/my group/C=c,/tikz/color=blue’.(B:b)(B:c)
\pgfkeys{/pgf/key filter handlers/append filtered to/.install key filter handler=\remainingoptions}
\def\remainingoptions{}
\pgfkeysfiltered{/my group/A1=a1, /my group/A2=a2,
/my group/B=b, /my group/C=c, /tikz/color=blue, /my group/A3=a3}
Remaining: ‘\remainingoptions’.
\pgfkeysalsofrom{\remainingoptions}
\pgfkeysalsofiltered{hkey-value-listi}
This command works as \pgfkeysfiltered, but it does not change the current default path. See the
documentation of \pgfkeysalso for more details.
\pgfkeysalsofilteredfrom{hmacroi}
A variant of \pgfkeysalsofiltered which loads its key list from {hmacroi}.
Key handler hkeyi/.install key filter=hoptional argumentsi
This handler installs a key filter. A key filter is a command key which sets the TEX-boolean \ifpgfkeysfiltercontinue, that means a key with existing ‘/.@cmd’ suffix. A simple example is a key
filter which returns always true:
\pgfkeys{/foo/bar/true key filter/.code={\pgfkeysfiltercontinuetrue}}
\pgfkeys{/foo/bar/true key filter/.install key filter}
If key filters require arguments, they are installed by .install key filter as well. An example is the
/pgf/key filters/equals handler:
(A1:a1)
\pgfkeys{/pgf/key filters/equals/.install key filter={/my group/A1}}
\pgfkeysfiltered{/my group/A1=a1, /my group/A2=a2,
/my group/B=b, /my group/C=c, /tikz/color=blue, /my group/A3=a3}
If a key filter requires more than one argument, you need to provide the complete argument list in braces
like {{first}{second}}.
You can also use \pgfkeysinstallkeyfilterhfull keyihoptional argumentsi, it has the same effect.
See section 82.6.7 for how to write key filters.
895
Key handler hkeyi/.install key filter handler=hoptional argumentsi
This handler installs the routine which will be invoked for every unprocessed option, that means any
option for which the key filter returned ‘false’.
The .install key filter handler is used in the same way as .install key filter. There exists a
macro version, \pgfkeysinstallkeyfilterhandlerhfull keyihoptional argumentsi, which has the same
effect.
See section 82.6.7 for how to write key filter handlers.
82.6.3
Handlers For Unprocessed Keys
Each option for which key filters decided to skip them is handed over to a ‘key filter handler’. There are
several predefined key filter handlers.
/pgf/key filter handlers/append filtered to={hmacroi}
(no default)
Install this filter handler to append any unprocessed options to macro {hmacroi}.
(A1:a1)(A2:a2)Remaining options: ‘/my group/B=b,/my group/C=c,/tikz/color=blue’.
\pgfkeys{/pgf/key filter handlers/append filtered to/.install key filter handler=\remainingoptions}
\def\remainingoptions{}
\pgfkeysfiltered{/my group/A1=a1, /my group/A2=a2,
/my group/B=b, /my group/C=c, /tikz/color=blue}
Remaining options: ‘\remainingoptions’.
This example uses the same keys as defined in the intro section 82.6.1.
(no value)
/pgf/key filter handlers/ignore
Install this filter handler if you simply want to ignore any unprocessed option. This is the default.
/pgf/key filter handlers/log
(no value)
This key filter handler writes messages for any unprocessed option to your logfile (and terminal).
82.6.4
Family Support
pgf supports a family concept: every option can be associated with (at most) one family. Families form
loose key groups which are independent of the key hierarchy. For example, /my tree/key1 can belong to
family /tikz.
It is possible to ‘activate’ or ‘deactivate’ single families. Furthermore, it is possible to set only keys which
belong to active families using appropriate key filter handlers.
The family support is fast: if there are N options in a key-value-list and there are K active families,
the runtime for \pgfkeysfiltered is O(N + K) (activate every family O(K), check every option O(N ),
deactivate every family O(K)).
Key handler hkeyi/.is family
Defines a new family. This option has already been described in section 82.4.1 on page 885.
Key handler hkeyi/.activate family
Activates a family. The family needs to be defined, otherwise /errors/family unknown will be raised.
Activation means a TEX-boolean will be set to true, indicating that a family should be processed.
You can also use \pgfkeysactivatefamilyhfull pathi to get the same effect. Furthermore, you can use
\pgfkeysactivatefamilieshlist of familiesihmacro name for de-activationi to activate a list of families
(see section 82.6.6).
Key handler hkeyi/.deactivate family
Deactivates a family. The family needs to be defined, otherwise /errors/family unknown will be
raised.
You can also use \pgfkeysdeactivatefamilyhfull pathi to get the same effect.
896
Key handler hkeyi/.belongs to family={hfamily namei}
Associates the current option with {hfamily namei}, which is expected to be a full path of a family.
\pgfkeys{/foo/bar/.is family}
\pgfkeys{
/foo/a/.belongs to family=/foo/bar,
/foo/b/.belongs to family=/foo/bar
}
Each option can have up to one family, .belongs to family overwrites any old setting.
(no value)
/pgf/key filters/active families
Install this key filter if \pgfkeysfiltered should only process activated families. If a key does not
belong to any family, it is not processed. If a key is completely unknown within the default path, the
normal ‘unknown’ handlers of \pgfkeys are invoked.
/pgf/key filters/active families or no family={hkey filter 1 i}{hkey filter 2 i}
(no default)
This key filter configures \pgfkeysfiltered to work as follows.
1. If the current key belongs to a family, set \ifpgfkeysfiltercontinue to true if and only if its
family is active.
2. If the current key does not belong to a family, assign \ifpgfkeysfiltercontinue as result of
{hkey filter 1 i}.
3. If the current key is unknown within the default path, assign \ifpgfkeysfiltercontinue as result
of {hkey filter 2 i}.
The arguments {hkey filter 1 i} and {hkey filter 2 i} are other key filters (possibly with options) and
allow fine-grained control over the filtering process.
\pgfkeysinstallkeyfilter
{/pgf/key filters/active families or no family}
{{/pgf/key filters/is descendant of=/tikz}% for keys without family
{/pgf/key filters/false}% for unknown keys
}%
This key filter will return true for any option with active family. If an option has no family, the return
value is true if and only if it belongs to /tikz. If the option is unknown, the return value is false and
unknown handlers won’t be called.
/pgf/key filters/active families or no family DEBUG={hkey filter 1 i}{hkey filter 2 i} (no default)
A variant of active families or no family which protocols each action on your terminal (log-file).
(no value)
/pgf/key filters/active families and known
A fast alias for
/pgf/key filters/active families or no family=
{/pgf/keys filters/false}
{/pgf/keys filters/false}.
/pgf/key filters/active families or descendants of={hpath prefix i}
(no default)
A fast alias for
/pgf/key filters/active families or no family=
{/pgf/keys filters/is descendant of={hpath prefix i}}
{/pgf/keys filters/false}.
\pgfkeysactivatefamiliesandfilteroptions{hfamily listi}{hkey-value-listi}
A simple shortcut macro which activates any family in the comma separated {hfamily listi}, invokes
\pgfkeysfilteredhkey-value-listi and deactivates the families afterwards.
Please note that you will need to install a family key filter, otherwise family activation has no effect.
897
\pgfqkeysactivatefamiliesandfilteroptions{hfamily listi}{hdefault pathi}{hkey-value-listi}
The ‘quick’ default path variant of \pgfkeysactivatefamiliesandfilteroptions.
\pgfkeysactivatesinglefamilyandfilteroptions{hfamily namei}{hkey-value-listi}
A shortcut macro which activates a single family and invokes \pgfkeysfiltered.
Please note that you will need to install a family key filter, otherwise family activation has no effect.
\pgfqkeysactivatesinglefamilyandfilteroptions{hfamily namei}{hdefault pathi}{hkey-value-listi}
The ‘quick’ default path variant of \pgfkeysactivatesinglefamilyandfilteroptions.
82.6.5
Other Key Filters
There are some more key filters which have nothing to do with family handling.
/pgf/key filters/is descendant of={hpathi}
(no default)
Install this key filter to process only options belonging to the key tree hpathi. It returns true for every
key whose key path is equal to hpathi. It also returns true for any unknown key, that means unknown
keys are processed using the standard unknown handlers of pgf.
(A:a)(B:b)
\pgfkeys{
/group 1/A/.code={(A:#1)},
/group 1/foo/bar/B/.code={(B:#1)},
/group 2/C/.code={(C:#1)},
/pgf/key filters/is descendant of/.install key filter=/group 1}
\pgfkeysfiltered{/group 1/A=a,/group 1/foo/bar/B=b,/group 2/C=c}
/pgf/key filters/equals={hfull keyi}
(no default)
Install this key filter to process only the fully qualified option {hfull keyi}. The filter returns true for
any unknown key or if the key equals {hfull keyi}.
(A:a)
\pgfkeys{
/group 1/A/.code={(A:#1)},
/group 1/B/.code={(B:#1)},
/pgf/key filters/equals/.install key filter=/group 1/A}
\pgfqkeysfiltered{/group 1}{A=a,B=b}
/pgf/key filters/not={hkey filter i}
This key filter logically inverts the result of {hkey filter i}.
(C:c)
(no default)
\pgfkeys{
/group 1/A/.code={(A:#1)},
/group 1/foo/bar/B/.code={(B:#1)},
/group 2/C/.code={(C:#1)},
/pgf/key filters/not/.install key filter=
{/pgf/key filters/is descendant of=/group 1}}
\pgfkeysfiltered{/group 1/A=a,/group 1/foo/bar/B=b,/group 2/C=c}
Please note that unknown keys will be handed to the usual unknown handlers.
/pgf/key filters/and={hkey filter 1 i}{hkey filter 2 i}
(no default)
This key filter returns true if and only if both, {hkey filter 1 i} and {hkey filter 2 i} return true.
/pgf/key filters/or={hkey filter 1 i}{hkey filter 2 i}
(no default)
This key filter returns true if one of {hkey filter 1 i} and {hkey filter 2 i} returns true.
(no value)
/pgf/key filters/true
This key filter returns always true.
(no value)
/pgf/key filters/false
This key filter returns always false (including unknown keys).
(no value)
/pgf/key filters/defined
This key filter returns false if the current key is unknown, which avoids calling the unknown handlers.
898
82.6.6
Programmer Interface
\pgfkeysinterruptkeyfilter
henvironment contentsi
\endpgfkeysinterruptkeyfilter
Temporarily disables key filtering inside the environment. If key filtering is not active, this has no effect
at all.
Please note that no TEX-group is introduced.
\pgfkeyssavekeyfilterstateto{hmacroi}
Creates {hmacroi} which contains commands to re-activate the current key filter and key filter handler.
It can be used to temporarily switch the key filter.
\pgfkeysinstallkeyfilter{hfull keyi}{hoptional argumentsi}
The command \pgfkeysinstallkeyfilter{hfull keyi}{hoptional argumentsi} has the same effect as
\pgfkeys{hfull keyi/.install key filter={hoptional argumentsi}}.
\pgfkeysinstallkeyfilterhandler{hfull keyi}{hoptional argumentsi}
The command \pgfkeysinstallkeyfilterhandler{hfull keyi}{hoptional argumentsi} has the same
effect as \pgfkeys{hfull keyi/.install key filter handler={hoptional argumentsi}}.
\pgfkeysactivatefamily{hfamily namei}
Equivalent to \pgfkeys{hfamily namei/.activate family}.
\pgfkeysdeactivatefamily{hfamily namei}
Equivalent to \pgfkeys{hfamily namei/.deactivate family}.
\pgfkeysactivatefamilies{hfamily listi}{hdeactivate macro namei}
Activates each family in hfamily listi and creates a macro hdeactivate macro namei which deactivates
each family in hfamily listi.
\pgfkeysactivatefamilies{/family 1,/family 2,/family 3}{\deactivatename}
\pgfkeysfiltered{foo,bar}
\deactivatename
\pgfkeysiffamilydefined{hfamilyi}{htrue casei}{hfalse casei}
Checks whether the full key hfamilyi is a family and executes either htrue casei or hfalse casei.
\pgfkeysisfamilyactive{hfamilyi}
Sets the TEX-boolean \ifpgfkeysfiltercontinue to whether hfamilyi is active or not.
\pgfkeysgetfamily{hkeyi}{hresultmacroi}
Returns the family associated to a full key hkeyi into macro hresultmacroi.
\pgfkeyssetfamily{hkeyi}{hfamilyi}
The command \pgfkeyssetfamily{hfull keyi}{hfamilyi} has the same effect as \pgfkeys{hfull
keyi/.belongs to family={hfamilyi}}.
82.6.7
Defining Own Filters Or Filter Handlers
During \pgfkeysfiltered, the key filter code will be invoked. At this time, the full key path including
key name is available as \pgfkeyscurrentkey, the key name before default paths have been considered as
\pgfkeyscurrentkeyRAW and the values as \pgfkeyscurrentvalue.
Furthermore, the macro \pgfkeyscasenumber contains the current key’s type as an integer:
h1 i The key is a command key (i.e. .../.@cmd exists).
h2 i The key contains its value directly.
899
h3 i The key is handled (for example it is .code or .cd).
In this case, the macros \pgfkeyscurrentname and \pgfkeyscurrentpath are set to the handlers
name and path, respectively. Invoke \pgfkeyssplitpath{} to extract these values for non-handled
keys.
h0 i The key is unknown.
Any key filter or key filter handler can access these variables. Key filters are expected to set the TEX-boolean
\ifpgfkeysfiltercontinue to whether the current key shall be processed or not.
\pgfkeysevalkeyfilterwith{hfull keyi}={hfilter argumentsi}
Evaluates a fully qualified key filter hfull keyi with argument(s) hfilter argumentsi.
\pgfkeysevalkeyfilterwith{/pgf/key filters/equals=/tikz}
900
83
Repeating Things: The Foreach Statement
This section describes the package pgffor, which is loaded automatically by Tik Z, but not by pgf:
\usepackage{pgffor} % LATEX
\input pgffor.tex
% plain TEX
\usemodule[pgffor] % ConTEXt
This package can be used independently of pgf, but works particularly well together with pgf and
Tik Z. It defines two new commands: \foreach and \breakforeach.
\foreachhvariablesi[hoptionsi]inhlisti hcommandsi
The syntax of this command is a bit complicated, so let us go through it step-by-step.
In the easiest case, hvariablesi is a single TEX-command like \x or \point. (If you want to have some
fun, you can also use active characters. If you do not know what active characters are, you are blessed.)
Still in the easiest case, hoptionsi will be omitted. The keys for customizing this command will be
discussed below.
Again, in the easiest case, hlisti is either a comma-separated list of values surrounded by curly braces
or it is the name of a macro that contain such a list of values. Anything can be used as a value, but
numbers are most likely.
Finally, in the easiest case, hcommandsi is some TEX-text in curly braces.
With all these assumptions, the \foreach statement will execute the hcommandsi repeatedly, once for
every element of the hlisti. Each time the hcommandsi are executed, the hvariablei will be set to the
current value of the list item.
[1][2][3][0]
\foreach \x in {1,2,3,0} {[\x]}
[1][2][3][0]
\def\mylist{1,2,3,0}
\foreach \x in \mylist {[\x]}
Note that in each execution of hcommandsi the hcommandsi are put in a TEX group. This means that
local changes to counters inside hcommandsi do not persist till the next iteration. For instance, if you
add 1 to a counter inside hcommandsi locally, then in the next iteration the counter will have the same
value it had at the beginning of the first iteration. You have to add \global if you wish changes to
persist from iteration to iteration.
Syntax for the commands. Let us move on to a more complicated setting. The first complication
occurs when the hcommandsi are not some text in curly braces. If the \foreach statement does not
encounter an opening brace, it will instead scan everything up to the next semicolon and use this as
hcommandsi. This is most useful in situations like the following:
\tikz
\foreach \x in {0,1,2,3}
\draw (\x,0) circle (0.2cm);
However, the “reading till the next semicolon” is not the whole truth. There is another rule: If a
\foreach statement is directly followed by another \foreach statement, this second foreach statement
is collected as hcommandsi. This allows you to write the following:
\begin{tikzpicture}
\foreach \x in {0,1,2,3}
\foreach \y in {0,1,2,3}
{
\draw (\x,\y) circle (0.2cm);
\fill (\x,\y) circle (0.1cm);
}
\end{tikzpicture}
The dots notation. The second complication concerns the hlisti. If this hlisti contains the list item
“...”, this list item is replaced by the “missing values.” More precisely, the following happens:
901
Normally, when a list item ... is encountered, there should already have been two list items before it,
which where numbers. Examples of numbers are 1, -10, or -0.24. Let us call these numbers x and y
and let d := y − x be their difference. Next, there should also be one number following the three dots,
let us call this number z.
In this situation, the part of the list reading “x,y,...,z” is replaced by “x, x + d, x + 2d, x + 3d, . . . ,
x + md,” where the last dots are semantic dots, not syntactic dots. The value m is the largest number
such that x + md ≤ z if d is positive or such that x + md ≥ z if d is negative.
Perhaps it is best to explain this by some examples: The following hlisti have the same effects:
\foreach \x in {1,2,...,6} {\x, } yields 1, 2, 3, 4, 5, 6,
\foreach \x in {1,2,3,...,6} {\x, } yields 1, 2, 3, 4, 5, 6,
\foreach \x in {1,3,...,11} {\x, } yields 1, 3, 5, 7, 9, 11,
\foreach \x in {1,3,...,10} {\x, } yields 1, 3, 5, 7, 9,
\foreach \x in {0,0.1,...,0.5} {\x, } yields 0, 0.1, 0.20001, 0.30002, 0.40002,
\foreach \x in {a,b,9,8,...,1,2,2.125,...,2.5} {\x, } yields a, b, 9, 8, 7, 6, 5, 4, 3, 2, 1, 2,
2.125, 2.25, 2.375, 2.5,
As can be seen, for fractional steps that are not multiples of 2−n for some small n, rounding errors
can occur pretty easily. Thus, in the second last case, 0.5 should probably be replaced by 0.501 for
robustness.
There is another special case for the ... statement: If the ... is used right after the first item in the
list, that is, if there is an x, but no y, the difference d obviously cannot be computed and is set to 1 if
the number z following the dots is larger than x and is set to −1 if z is smaller:
\foreach \x in {1,...,6} {\x, } yields 1, 2, 3, 4, 5, 6,
\foreach \x in {9,...,3.5} {\x, } yields 9, 8, 7, 6, 5, 4,
There is a yet another special case for the ... statement, in that it can indicate an alphabetic character
sequence:
\foreach \x in {a,...,m} {\x, } yields a, b, c, d, e, f, g, h, i, j, k, l, m,
\foreach \x in {Z,X,...,M} {\x, } yields Z, X, V, T, R, P, N,
A final special case for the ... statement is contextual replacement. If the ... is used in some context,
for example, sin(...), this context will be interpreted correctly, provided that the list items prior to
the ... statement have exactly the same pattern, except that, instead of dots, they have a number or
a character:
\foreach \x in {2^1,2^...,2^7} {$\x$, } yields 21 , 22 , 23 , 24 , 25 , 26 , 27 ,
\foreach \x in {0\pi,0.5\pi,...\pi,3\pi} {$\x$, } yields 0π, 0.5π, 1π, 1.5π, 2π, 2.5π, 3π,
\foreach \x in {A_1,..._1,H_1} {$\x$, } yields A1 , B1 , C1 , D1 , E1 , F1 , G1 , H1 ,
Special handling of pairs. Different list items are separated by commas. However, this causes a
problem when the list items contain commas themselves as pairs like (0,1) do. In this case, you should
put the items containing commas in braces as in {(0,1)}. However, since pairs are such a natural and
useful case, they get a special treatment by the \foreach statement. When a list item starts with a (
everything up to the next ) is made part of the item. Thus, we can write things like the following:
\tikz
\foreach \position in {(0,0), (1,1), (2,0), (3,1)}
\draw \position rectangle +(.25,.5);
Using the foreach-statement inside paths. Tik Z allows you to use foreach and \foreach (both
have the same effect) inside a path construction. In such a case, the hcommandsi must be path construction commands. Here are two examples:
\tikz
\draw (0,0)
foreach \x in {1,...,3}
{ -- (\x,1) -- (\x,0) }
;
902
\tikz \draw foreach \p in {1,...,3} {(\p,1)--(\p,3) (1,\p)--(3,\p)};
Note that the node and pic path commands also support the foreach statement in special ways.
Multiple variables. You will often wish to iterate over two variables at the same time. Since you
can nest \foreach loops, this is normally straight-forward. However, you sometimes wish variables to
iterate “simultaneously.” For example, we might be given a list of edges that connect two coordinates
and might wish to iterate over these edges. While doing so, we would like the source and target of the
edges to be set to two different variables.
To achieve this, you can use the following syntax: The hvariablesi may not only be a single TEX-variable.
Instead, it can also be a list of variables separated by slashes (/). In this case the list items can also be
lists of values separated by slashes.
Assuming that the hvariablesi and the list items are lists of values, each time the hcommandsi are
executed, each of the variables in hvariablesi is set to one part of the list making up the current list
item. Here is an example to clarify this:
Example: \foreach \x / \y in {1/2,a/b} {“\x\ and \y”} yields “1 and 2”“a and b”.
If some entry in the hlisti does not have “enough” slashes, the last entry will be repeated. Here is an
example:
0
1
e3
2
\begin{tikzpicture}
\foreach \x/\xtext in {0,...,3,2.72 / e}
\draw (\x,0) node{$\xtext$};
\end{tikzpicture}
Here are more useful examples:
c
d
b
a
\begin{tikzpicture}
% Define some coordinates:
\path[nodes={circle,fill=yellow!80!black,draw}]
(0,0)
node(a) {a}
(2,0.55) node(b) {b}
(1,1.5) node(c) {c}
(2,1.75) node(d) {d};
% Draw some connections:
\foreach \source/\target in {a/b, b/c, c/a, c/d}
\draw (\source) .. controls +(.75cm,0pt) and +(-.75cm,0pt)..(\target);
\end{tikzpicture}
\begin{tikzpicture}
% Let’s draw circles at interesting points:
\foreach \x / \y / \diameter in {0 / 0 / 2mm, 1 / 1 / 3mm, 2 / 0 / 1mm}
\draw (\x,\y) circle (\diameter);
% Same effect
\foreach \center/\diameter in {{(0,0)/2mm}, {(1,1)/3mm}, {(2,0)/1mm}}
\draw[yshift=2.5cm] \center circle (\diameter);
\end{tikzpicture}
903
11
12
1
10
2
9
3
8
4
7
6
5
\begin{tikzpicture}[line cap=round,line width=3pt]
\filldraw [fill=yellow!80!black] (0,0) circle (2cm);
\foreach \angle / \label in
{0/3, 30/2, 60/1, 90/12, 120/11, 150/10, 180/9,
210/8, 240/7, 270/6, 300/5, 330/4}
{
\draw[line width=1pt] (\angle:1.8cm) -- (\angle:2cm);
\draw (\angle:1.4cm) node{\textsf{\label}};
}
\foreach \angle in {0,90,180,270}
\draw[line width=2pt] (\angle:1.6cm) -- (\angle:2cm);
\draw (0,0) -- (120:0.8cm); % hour
\draw (0,0) -- (90:1cm);
% minute
\end{tikzpicture}%
\tikz[shading=ball]
\foreach \x / \cola in {0/red,1/green,2/blue,3/yellow}
\foreach \y / \colb in {0/red,1/green,2/blue,3/yellow}
\shade[ball color=\cola!50!\colb] (\x,\y) circle (0.4cm);
Options to customize the foreach-statement.
The keys described below can be used in the hoptionsi argument to the \foreach command. They all
have the path /pgf/foreach/, however, the path is set automatically when hoptionsi are parsed, so it
does not have to be explicitly stated.
(no default)
/pgf/foreach/var=hvariablei
This key provides an alternative way to specify variables: \foreach [var=\x,var=\y] is the same
as \foreach \x/\y. If used, this key should be used before the other keys.
/pgf/foreach/evaluate=hvariableiashmacroiusinghformulai
(no default)
By default, list items are not evaluated: 1+2, yields 1+2, not 3. This key allows a variable to be
evaluated using the mathematical engine. The variable must have been specified either using the
var key or in the hvariablesi argument of the foreach command. By default, the result of the
evaluation will be stored in hvariablei. However, the optional as hmacroi statement can be used
to store the result in hmacroi.
1.0, 2.0, 4.0, 8.0, 16.0, 32.0, 64.0, 128.0, 256.0,
\foreach \x [evaluate=\x] in {2^0,2^...,2^8}{$\x$, }
20 = 1.0, 21 = 2.0, 22 = 4.0, 23 = 8.0, 24 = 16.0, 25 = 32.0, 26 = 64.0, 27 = 128.0, 28 = 256.0,
\foreach \x [evaluate=\x as \xeval] in {2^0,2^...,2^8}{$\x=\xeval$, }
904
The optional using hformulai statement means an evaluation does not have to be explicitly stated
for each item in hlisti. The hformulai should contain at least one reference to hvariablei.
0
1
2
3
4
5
6
7
8
9
10
\tikz\foreach \x [evaluate=\x as \shade using \x*10] in {0,1,...,10}
\node [fill=red!\shade!yellow, minimum size=0.65cm] at (\x,0) {\x};
/pgf/foreach/remember=hvariableiashmacroi(initiallyhvaluei)
(no default)
This key allows the item value stored in hvariablei to be remembered during the next iteration,
stored in hmacroi. If a variable is evaluated, the result of this evaluation is remembered. By default
the value of hvariablei is zero for the first iteration, however, the optional (initially hvaluei)
statement, allows the hmacroi to be initially defined as hvaluei.
−−→ −−→ −−→ −−→ −−→ −−→ −−→
AB, BC, CD, DE, EF , F G, GH,
\foreach \x [remember=\x as \lastx (initially A)] in {B,...,H}{$\overrightarrow{\lastx\x}$, }
/pgf/foreach/count=hmacroifromhvaluei
(no default)
This key allows hmacroi to hold the position in the list of the current item. The optional from
hvaluei statement allows the counting to begin from hvaluei.
aa
bb
cc
dd
ab
bc
cd
de
ac
bd
ce
ad
be
ee
\tikz[x=0.75cm,y=0.75cm]
\foreach \x [count=\xi] in {a,...,e}
\foreach \y [count=\yi] in {\x,...,e}
\node [draw, top color=white, bottom color=blue!50, minimum size=0.666cm]
at (\xi,-\yi) {$\mathstrut\x\y$};
ae
\breakforeach
If this command is given inside a \foreach command, no further executions of the hcommandsi will
occur. However, the current execution of the hcommandsi is continued normally, so it is probably best
to use this command only at the end of a \foreach command.
\begin{tikzpicture}
\foreach \x in {1,...,4}
\foreach \y in {1,...,4}
{
\fill[red!50] (\x,\y) ellipse (3pt and 6pt);
\ifnum \x<\y
\breakforeach
\fi
}
\end{tikzpicture}
905
84
Date and Calendar Utility Macros
This section describes the package pgfcalendar.
\usepackage{pgfcalendar} % LATEX
\input pgfcalendar.tex
% plain TEX
\usemodule[pgfcalendar] % ConTEXt
This package can be used independently of pgf. It has two purposes:
1. It provides functions for working with dates. Most noticeably, it can convert a date in ISO-standard
format (like 1975-12-26) to a so-called Julian day number, which is defined in Wikipedia as follows:
“The Julian day or Julian day number is the (integer) number of days that have elapsed since
the initial epoch at noon Universal Time (UT) Monday, January 1, 4713 BC in the proleptic
Julian calendar.” The package also provides a function for converting a Julian day number to an
ISO-format date.
Julian day numbers make it very easy to work with days. For example, the date ten days in the
future of 2008-02-20 can be computed by converting this date to a Julian day number, adding 10,
and then converting it back. Also, the day of week of a given date can be computed by taking the
Julian day number modulo 7.
2. It provides a macro for typesetting a calendar. This macro is highly configurable and flexible (for
example, it can produce both plain text calendars and also complicated Tik Z-based calendars), but
most users will not use the macro directly. It is the job of a frontend to provide useful configurations
for typesetting calendars based on this command.
84.1
Handling Dates
84.1.1
Conversions Between Date Types
\pgfcalendardatetojulian{hdatei}{hcounter i}
This macro converts a date in a format to be described in a moment to the Julian day number in the
Gregorian calendar. The hdatei should expand to a string of the following form:
1. It should start with a number representing the year. Use \year for the current year, that is, the
year the file is being typeset.
2. The year must be followed by a hyphen.
3. Next should come a number representing the month. Use \month for the current month. You can,
but need not, use leading zeros. For example, 02 represents February, just like 2.
4. The month must also be followed by a hyphen.
5. Next you must either provide a day of month (again, a number and, again, \day yields the current
day of month) or the keyword last. This keyword refers to the last day of the month, which is
automatically computed (and which is a bit tricky to compute, especially for February).
6. Optionally, you can next provide a plus sign followed by positive or negative number. This number
of days will be added to the computed date.
Here are some examples:
• 2006-01-01 refers to the first day of 2006.
• 2006-02-last refers to February 28, 2006.
• \year-\month-\day refers to today.
• 2006-01-01+2 refers to January 3, 2006.
• \year-\month-\day+1 refers to tomorrow.
• \year-\month-\day+-1 refers to yesterday.
The conversion method is taken from the English Wikipedia entry on Julian days.
Example: \pgfcalendardatetojulian{2007-01-14}{\mycount} sets \mycount to 2454115.
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\pgfcalendarjuliantodate{hJulian dayi}{hyear macroi}{hmonth macroi}{hday macroi}
This command converts a Julian day number to an ISO-date. The hJulian dayi must be a number or
TEX counter, the hyear macroi, hmonth macroi and hday macroi must be TEX macro names. They
will be set to numbers representing the year, month, and day of the given Julian day in the Gregorian
calendar.
The hyear macroi will be assigned the year without leading zeros. Note that this macro will produce
year 0 (as opposed to other calendars, where year 0 does not exist). However, if you really need calendars
for before the year 1, it is expected that you know what you are doing anyway.
The hmonth macroi gets assigned a two-digit number representing the month (with a leading zero, if
necessary). Thus, the macro is set to 01 for January.
The hday macroi gets assigned a two-digit number representing the day of the month (again, possibly
with a leading zero).
To convert a Julian day number to an ISO-date you use code like the following:
\pgfcalendardatetojulian{2454115}{\myyear}{\mymonth}{\myday}
\edef\isodate{\myyear-\mymonth-\myday}
The above code sets \isodate to 2007-01-14.
\pgfcalendarjuliantoweekday{hJulian dayi}{hweek day counter i}
This command converts a Julian day to a week day by computing the day modulo 7. The hweek day
counter i must be a TEX counter. It will be set to 0 for a Monday, to 1 for a Tuesday, and so on.
Example: \pgfcalendarjuliantoweekday{2454115}{\mycount} sets \mycount to 6 (it was a Sunday).
84.1.2
Checking Dates
\pgfcalendarifdate{hdatei}{htestsi}{hcodei}{helse codei}
This command is used to execute code based on properties of hdatei. The hdatei must be a date in
ISO-format. For this date, the htestsi are checked (to be detailed later) and if one of the tests succeeds,
the hcodei is executed. If none of the tests succeeds, the helse codei is executed.
Example: \pgfcalendarifdate{2007-02-07}{Wednesday}{Is a Wednesday}{Is not a Wednesday}
yields Is a Wednesday.
The htestsi is a comma-separated list of key-value pairs. The following are defined by default:
• all This test is passed by all dates.
• Monday This test is passed by all dates that are Mondays.
• Tuesday as above.
• Wednesday as above.
• Thursday as above.
• Friday as above.
• Saturday as above.
• Sunday as above.
• workday Passed by Mondays, Tuesdays, Wednesdays, Thursdays, and Fridays.
• weekend Passed by Saturdays and Sundays.
• equals=hreferencei The hreferencei can be in one of two forms: Either, it is a full ISO format date
like 2007-01-01 or the year may be missing as in 12-31. In the first case, the test is passed if
hdatei is the same as hreferencei. In the second case, the test is passed if the month and day part
of hdatei is the same as hreferencei.
For example, the test equals=2007-01-10 will only be passed by this particular date. The test
equals=05-01 will be passed by every first of May on any year.
• at least=hreferencei This test works similarly to the equals test, only it is checked whether
hdatei is equal to hreferencei or to any later date. Again, the hreferencei can be a full date like
2007-01-01 or a short version like 07-01. For example, at least=07-01 is true for every day in
the second half of any year.
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• at most=hreferencei as above.
• between=hstart referencei and hend referencei This test checks whether the current date lies between the two given reference dates. Both full and short version may be given.
For example between=2007-01-01 and 2007-02-28 is true for the days in January and February
of 2007.
For another example, between=05-01 and 05-07 is true for the days of the first week of May of
any year.
• day of month=hnumber i Passed by the day of month of the hdatei that is hnumber i. For example,
the test day of month=1 is passed by every first of every month.
• end of month=hnumber i Passed by the day of month of the hdatei that is hnumber i from the end
of the month. For example, the test end of month=1 is passed by the last day of every month,
the test end of month=2 is passed by the second last day of every month. If hnumber i is omitted,
it is assumed to be 1.
In addition to the above checks, you can also define new checks. To do so, you must add a new key
to the path /pgf/calendar/ using the \pgfkeys command. The job of the code of this new key is
to possibly set the TEX-if \ifpgfcalendarmatches to true (if it is already true, no action should be
taken) to indicate that the hdatei passes the test setup by this new key.
In order to perform the test, the key code needs to know the date that should be checked. The date is
available through a macro, but a whole bunch of additional information about this date is also available
through the following macros:
• \pgfcalendarifdatejulian is the Julian day number of the hdatei to be checked.
• \pgfcalendarifdateweekday is the weekday of the hdatei to be checked.
• \pgfcalendarifdateyear is the year of the hdatei to be checked.
• \pgfcalendarifdatemonth is the month of the hdatei to be checked.
• \pgfcalendarifdateday is the day of month of the hdatei to be checked.
For example, let us define a new key that checks whether the hdatei is a Workers day (May 1st). This
can be done as follows:
\pgfkeys{/pgf/calendar/workers day/.code=%
{
\ifnum\pgfcalendarifdatemonth=5\relax
\ifnum\pgfcalendarifdateday=1\relax
\pgfcalendarmatchestrue
\fi
\fi
}}
84.1.3
Typesetting Dates
\pgfcalendarweekdayname{hweek day number i}
This command expands to a textual representation of the day of week, given by the hweek day number i.
Thus, \pgfcalendarweekdayname{0} expands to Monday if the current language is English and to
Montag if the current language is German, and so on. See Section 84.1.4 for more details on translations.
Example: \pgfcalendarweekdayname{2} yields Wednesday.
\pgfcalendarweekdayshortname{hweek day number i}
This command works similarly to the previous command, only an abbreviated version of the week day
is produced.
Example: \pgfcalendarweekdayshortname{2} yields Wed.
\pgfcalendarmonthname{hmonth number i}
This command expands to a textual representation of the month, which is given by the hmonth number i.
Example: \pgfcalendarmonthname{12} yields December.
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\pgfcalendarmonthshortname{hmonth number i}
As above, only an abbreviated version is produced.
Example: \pgfcalendarmonthshortname{12} yields Dec.
84.1.4
Localization
All textual representations of week days or months (like “Monday” or “February”) are wrapped with \translate commands from the translator package (it this package is not loaded, no translation takes place).
Furthermore, the pgfcalendar package will try to load the translator-months-dictionary, if the translator package is loaded.
The net effect of all this is that all dates will be translated to the current language setup in the translator
package. See the documentation of this package for more details.
84.2
Typesetting Calendars
\pgfcalendar{hprefix i}{hstart datei}{hend datei}{hrendering codei}
This command can be used to typeset a calendar. It is a very general command, the actual work has to
be done by giving clever implementations of hrendering codei. Note that this macro need not be called
inside a {pgfpicture} environment (even though it typically will be) and you can use it to typeset
calendars in normal TEX or using packages other than pgf.
Basic typesetting process. A calendar is typeset as follows: The hstart datei and hend datei specify
a range of dates. For each date in this range the hrendering codei is executed with certain macros setup
to yield information about the current date (the current date in the enumeration of dates of the range).
Typically, the hrendering codei places nodes inside a picture, but it can do other things as well. Note
that it is also the job of the hrendering codei to position the calendar correctly.
The different calls of the hrending codei are not surrounded by TEX groups (though you can do so
yourself, of course). This means that settings can accumulate between different calls, which is often
desirable and useful.
Information about the current date. Inside the hrendering codei, different macros can be access:
• \pgfcalendarprefix The hprefix i parameter. This prefix is recommended for nodes inside the
calendar, but you have to use it yourself explicitly.
• \pgfcalendarbeginiso The hstart datei of range being typeset in ISO format (like 2006-01-10).
• \pgfcalendarbeginjulian Julian day number of hstart datei.
• \pgfcalendarendiso The hend datei of range being typeset in ISO format.
• \pgfcalendarendjulian Julian day number of hend datei.
• \pgfcalendarcurrentjulian This TEX count holds the Julian day number of the day currently
being rendered.
• \pgfcalendarcurrentweekday The weekday (a number with zero representing Monday) of the
current date.
• \pgfcalendarcurrentyear The year of the current date.
• \pgfcalendarcurrentmonth The month of the current date (always two digits with a leading zero,
if necessary).
• \pgfcalendarcurrentday The day of month of the current date (always two digits).
The \ifdate command. Inside the \pgfcalendar the macro \ifdate is available locally:
\ifdate{htestsi}{hcodei}{helse codei}
This command has the same effect as calling \pgfcalendarifdate for the current date.
Examples. In a first example, let us create a very simple calendar: It just lists the dates in a certain
range.
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\pgfcalendar{cal}{2007-01-20}{2007-02-10}{\pgfcalendarcurrentday\ }
Let us now make this a little more interesting: Let us add a line break after each Sunday.
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\pgfcalendar{cal}{2007-01-20}{2007-02-10}
{
\pgfcalendarcurrentday\
\ifdate{Sunday}{\par}{}
}
We now want to have all Mondays to be aligned on a column. For this, different approaches work. Here
is one based positioning each day horizontally using a skip.
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\pgfcalendar{cal}{2007-01-20}{2007-02-10}
{%
\leavevmode%
\hbox to0pt{\hskip\pgfcalendarcurrentweekday cm\pgfcalendarcurrentday\hss}%
\ifdate{Sunday}{\par}{}%
}
Let us now typeset two complete months.
January
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\pgfcalendar{cal}{2007-01-01}{2007-02-28}{%
\ifdate{day of month=1}{
\par\bigskip\hbox to7.5cm{\itshape\hss\pgfcalendarshorthand mt\hss}\par
}{}%
\leavevmode%
{%
\ifdate{weekend}{\color{black!50}}{\color{black}}%
\hbox to0pt{%
\hskip\pgfcalendarcurrentweekday cm%
\hbox to1cm{\hss\pgfcalendarshorthand d-}\hss%
}%
}%
\ifdate{Sunday}{\par}{}%
}
For our final example, we use a {tikzpicture}.
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\begin{tikzpicture}
\pgfcalendar{cal}{2007-01-20}{2007-02-10}{%
\ifdate{workday}
{\tikzset{filling/.style={fill=blue!20}}}
{\tikzset{filling/.style={fill=red!20}}}
\node (\pgfcalendarsuggestedname) at (\pgfcalendarcurrentweekday,0)
[anchor=base,circle,filling] {\pgfcalendarcurrentday};
\ifdate{Sunday}{\pgftransformyshift{-3em}}{}%
}
\draw (cal-2007-01-21) -- (cal-2007-02-03);
\end{tikzpicture}
\pgfcalendarshorthand{hkind i}{hrepresentationi}
This command can be used inside a \pgfcalendar, where it will expand to a representation of the current
day, month, year or day of week, depending on whether hkind i is d, m, y or w. The hrepresentationi can
be one of the following: -, =, 0, ., and t. They have the following meanings:
• The minus sign selects the shortest numerical representation possible (no leading zeros).
• The equal sign also selects the shortest numerical representation, but a space is added to single
digit days and months (thereby ensuring that they have the same length as other days).
• The zero digit selects a two-digit numerical representation for days and months. For years it is
allowed, but has no effect.
• The letter t selects a textual representation.
• The dot selects an abbreviated textual representation.
Normally, you should say \let\%=\pgfcalendarshorthand locally, so that you can write \%wt instead
of the much more cumbersome \pgfcalendarshorthand{w}{t}.
ISO form: 2007-01-20, long form: Saturday, January 20, 2007
\let\%=\pgfcalendarshorthand
\pgfcalendar{cal}{2007-01-20}{2007-01-20}
{ ISO form: \%y0-\%m0-\%d0, long form: \%wt, \%mt \%d-, \%y0}
\pgfcalendarsuggestedname
This macro expands to a suggested name for nodes representing days in a calendar. If the hprefix i is
empty, it expands to the empty string, otherwise it expands to the hprefix i of the calendar, followed by
a hyphen, followed by the ISO format version of the date. Thus, when the date 2007-01-01 is typeset
in a calendar for the prefix mycal, the macro expands to mycal-2007-01-01.
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85
Page Management
This section describes the pgfpages package. Although this package is not concerned with creating pictures,
its implementation relies so heavily on pgf that it is documented here. Currently, pgfpages only works
with LATEX, but if you are adventurous, feel free to hack the code so that it also works with plain TEX.
The aim of pgfpages is to provide a flexible way of putting multiple pages on a single page inside TEX.
Thus, pgfpages is quite different from useful tools like psnup or pdfnup insofar as it creates its output in a
single pass. Furthermore, it works uniformly with both latex and pdflatex, making it easy to put multiple
pages on a single page without any fuss.
A word of warning: using pgfpages will destroy hyperlinks. Actually, the hyperlinks are not destroyed,
only they will appear at totally wrong positions on the final output. This is due to a fundamental flaw in
the pdf specification: In pdf the bounding rectangle of a hyperlink is given in “absolute page coordinates”
and translations or rotations do not affect them. Thus, the transformations applied by pgfpages to put the
pages where you want them are (cannot, even) be applied to the coordinates of hyperlinks. It is unlikely
that this will change in the foreseeable future.
85.1
Basic Usage
The internals of pgfpages are complex since the package can do all sorts of interesting tricks. For this
reason, so-called layouts are predefined that set up all option in appropriate ways.
You use a layout as follows:
\documentclass{article}
\usepackage{pgfpages}
\pgfpagesuselayout{2 on 1}[a4paper,landscape,border shrink=5mm]
\begin{document}
This text is shown on the left.
\clearpage
This text is shown on the right.
\end{document}
The layout 2 on 1 puts two pages on a single page. The option a4paper tells pgfpages that the resulting
page (called the physical page in the following) should be a4paper and it should be landscape (which is quite
logical since putting two portrait pages next to each other gives a landscape page). Normally, the logical
pages, that is, the pages that TEX “thinks” that it is typesetting, will have the same sizes, but this need not
be the case. pgfpages will automatically scale down the logical pages such that two logical pages fit next
to each other inside a DIN A4 page.
The border shrink tells pgfpages that it should add an additional 5mm to the shrinking such that a
5mm-wide border is shown around the resulting logical pages.
As a second example, let us put two pages produced by the beamer class on a single page:
\documentclass{beamer}
\usepackage{pgfpages}
\pgfpagesuselayout{2 on 1}[a4paper,border shrink=5mm]
\begin{document}
\begin{frame}
This text is shown at the top.
\end{frame}
\begin{frame}
This text is shown at the bottom.
\end{frame}
\end{document}
Note that we do not use the landscape option since beamer’s logical pages are already in landscape
mode and putting two landscape pages on top of each other results in a portrait page. However, if you had
used the 4 on 1 layout, you would have had to add landscape once more, using the 8 on 1 you must not,
using 16 on 1 you need it yet again. And, no, there is no 32 on 1 layout.
Another word of caution: using pgfpages will produce wrong page numbers in the .aux file. The reason is that TEX instantiates the page numbers when writing an .aux file only when the physical page
is shipped out. Fortunately, this problem is easy to fix: First, typeset our file normally without using
the \pgfpagesuselayout command (just put the comment marker % before it) Then, rerun TEX with the
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\pgfpagesuselayout command included and add the command \nofiles. This command ensures that the
.aux file is not modified, which is exactly what you want. So, to typeset the above example, you should
actually first TEX the following file:
\documentclass{article}
\usepackage{pgfpages}
%%\pgfpagesuselayout{2 on 1}[a4paper,landscape,border shrink=5mm]
%%\nofiles
\begin{document}
This text is shown on the left.
\clearpage
This text is shown on the right.
\end{document}
and then typeset
\documentclass{article}
\usepackage{pgfpages}
\pgfpagesuselayout{2 on 1}[a4paper,landscape,border shrink=5mm]
\nofiles
\begin{document}
This text is shown on the left.
\clearpage
This text is shown on the right.
\end{document}
The final basic example is the resize to layout (it works a bit like a hypothetical 1 on 1 layout). This
layout resizes the logical page such that is fits the specified physical size. Since this does not change the page
numbering, you need not worry about the .aux files with this layout. For example, adding the following
lines will ensure that the physical output will fit on DIN A4 paper:
\usepackage{pgfpages}
\pgfpagesuselayout{resize to}[a4paper]
This can be very useful when you have to handle lots of papers that are typeset for, say, letter paper and
you have an A4 printer or the other way round. For example, the following article will be fit for printing on
letter paper:
\documentclass[a4paper]{article}
%% a4 is currently the logical size and also the physical size
\usepackage{pgfpages}
\pgfpagesuselayout{resize to}[letterpaper]
%% a4 is still the logical size, but letter is the physical one
\begin{document}
\title{My Great Article}
...
\end{document}
85.2
The Predefined Layouts
This section explains the predefined layouts in more detail. You select a layout using the following command:
\pgfpagesuselayout{hlayouti}[hoptionsi]
Installs the specified hlayouti with the given hoptionsi. The predefined layouts and their permissible
options are explained below.
If this function is called multiple times, only the last call “wins.” You can thereby overwrite any previous
settings. In particular, layouts do not accumulate.
Example: \pgfpagesuselayout{resize to}[a4paper]
\pgfpagesuselayout{resize to}[hoptionsi]
This layout is used to resize every logical page to a specified physical size. To determine the target size,
the following options may be given:
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• physical paper height=hsizei sets the height of the physical page size to hsizei.
• physical paper width=hsizei sets the width of the physical Pappe size to hsizei.
• a0paper sets the physical page size to DIN A0 paper.
• a1paper sets the physical page size to DIN A1 paper.
• a2paper sets the physical page size to DIN A2 paper.
• a3paper sets the physical page size to DIN A3 paper.
• a4paper sets the physical page size to DIN A4 paper.
• a5paper sets the physical page size to DIN A5 paper.
• a6paper sets the physical page size to DIN A6 paper.
• letterpaper sets the physical page size to the American letter paper size.
• legalpaper sets the physical page size to the American legal paper size.
• executivepaper sets the physical page size to the American executive paper size.
• landscape swaps the height and the width of the physical paper.
• border shrink=hsizei additionally reduces the size of the logical page on the physical page by
hsizei.
\pgfpagesuselayout{2 on 1}[hoptionsi]
Puts two logical pages alongside each other on each physical page if the logical height is larger than the
logical width (logical pages are in portrait mode). Otherwise, two logical pages are put on top of each
other (logical pages are in landscape mode). When using this layout, it is advisable to use the \nofiles
command, but this is not done automatically.
The same hoptionsi as for the resize to layout can be used, plus the following option:
• odd numbered pages right places the first page on the right.
\pgfpagesuselayout{4 on 1}[hoptionsi]
Puts four logical pages on a single physical page. The same hoptionsi as for the resize to layout can
be used.
\pgfpagesuselayout{8 on 1}[hoptionsi]
Puts eight logical pages on a single physical page. As for 2 on 1 and 4 on 1, the orientation depends
on whether the logical pages are in landscape mode or in portrait mode.
\pgfpagesuselayout{16 on 1}[hoptionsi]
This is for the ceo.
\pgfpagesuselayout{rounded corners}[hoptionsi]
This layout adds “rounded corners” to every page, which, supposedly, looks nicer during presentations
with projectors (personally, I doubt this). This is done by (possibly) resizing the page to the physical
page size. Then four black rectangles are drawn in each corner. Next, a clipping region is set up that
contains all of the logical page except for little rounded corners. Finally, the logical page is drawn and
clipped against the clipping region.
Note that every logical page should fill its background for this to work.
In addition to the hoptionsi that can be given to resize to, the following options may be given.
• corner width=hsizei specifies the size of the corner.
\documentclass{beamer}
\usepackage{pgfpages}
\pgfpagesuselayout{rounded corners}[corner width=5pt]
\begin{document}
...
\end{document}
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\pgfpagesuselayout{two screens with lagging second}[hoptionsi]
This layout puts two logical pages alongside each other. The second page always shows what the main
page showed on the previous physical page. Thus, the second page “lags behind” the main page. This
can be useful when you have two projectors attached to your computer and can show different parts of
a physical page on different projectors.
The following hoptionsi may be given:
• second right puts the second page right of the main page. This will make the physical pages
twice as wide as the logical pages, but it will retain the height.
• second left puts the second page left, otherwise it behaves the same as second right.
• second bottom puts the second page below the main page. This make the physical pages twice as
high as the logical ones.
• second top works like second bottom.
\pgfpagesuselayout{two screens with optional second}[hoptionsi]
This layout works similarly to two screens with lagging second. The difference is that the contents
of the second screen only changes when one of the commands \pgfshipoutlogicalpage{2}{hbox i} or
\pgfcurrentpagewillbelogicalpage{2} is called. The first puts the given hbox i on the second page.
The second specifies that the current page should be put there, once it is finished.
The same options as for two screens with lagging second may be given.
You can define your own predefined layouts using the following command:
\pgfpagesdeclarelayout{hlayouti}{hbefore actionsi}{hafter actionsi}
This command predefines a hlayouti that can later be installed using the \pgfpagesuselayout command.
When \pgfpagesuselayout{hlayouti}[hoptionsi] is called, the following happens: First, the hbefore
actionsi are executed. They can be used, for example, to set up default values for keys. Next,
\setkeys{pgfpagesuselayoutoption}{hoptionsi} is executed. Finally, the hafter actionsi are executed.
Here is an example:
\pgfpagesdeclarelayout{resize to}
{
\def\pgfpageoptionborder{0pt}
}
{
\pgfpagesphysicalpageoptions
{%
logical pages=1,%
physical height=\pgfpageoptionheight,%
physical width=\pgfpageoptionwidth%
}
\pgfpageslogicalpageoptions{1}
{%
resized width=\pgfphysicalwidth,%
resized height=\pgfphysicalheight,%
border shrink=\pgfpageoptionborder,%
center=\pgfpoint{.5\pgfphysicalwidth}{.5\pgfphysicalheight}%
}%
}
85.3
Defining a Layout
If none of the predefined layouts meets your problem or if you wish to modify them, you can create layouts
from scratch. This section explains how this is done.
Basically, pgfpages hooks into TEX’s \shipout function. This function is called whenever TEX has
completed typesetting a page and wishes to send this page to the .dvi or .pdf file. The pgfpages package
redefines this command. Instead of sending the page to the output file, pgfpages stores it in an internal box
and then acts as if the page had been output. When TEX tries to output the next page using \shipout, this
call is once more intercepted and the page is stored in another box. These boxes are called logical pages.
915
At some point, enough logical pages have been accumulated such that a physical page can be output.
When this happens, pgfpages possibly scales, rotates, and translates the logical pages (and possibly even
does further modifications) and then puts them at certain positions of the physical page. Once this page is
fully assembled, the “real” or “original” \shipout is called to send the physical page to the output file.
In reality, things are slightly more complicated. First, once a physical page has been shipped out, the
logical pages are usually voided, but this need not be the case. Instead, it is possible that certain logical
pages just retain their contents after the physical page has been shipped out and these pages need not be
filled once more before a physical shipout can occur. However, the contents of these logical pages can still
be changed using special commands. It is also possible that after a shipout certain logical pages are filled
with the contents of other logical pages.
A layout defines for each logical page where it will go on the physical page and which further modifications
should be done. The following two commands are used to define the layout:
\pgfpagesphysicalpageoptions{hoptionsi}
This command sets the characteristics of the “physical” page. For example, it is used to specify
how many logical pages there are and how many logical pages must be accumulated before a physical page is shipped out. How each individual logical page is typeset is specified using the command
\pgfpageslogicalpageoptions, described later.
Example: A layout for putting two portrait pages on a single landscape page:
\pgfpagesphysicalpageoptions
{%
logical pages=2,%
physical height=\paperwidth,%
physical width=\paperheight,%
}
\pgfpageslogicalpageoptions{1}
{%
resized width=.5\pgfphysicalwidth,%
resized height=\pgfphysicalheight,%
center=\pgfpoint{.25\pgfphysicalwidth}{.5\pgfphysicalheight}%
}%
\pgfpageslogicalpageoptions{2}
{%
resized width=.5\pgfphysicalwidth,%
resized height=\pgfphysicalheight,%
center=\pgfpoint{.75\pgfphysicalwidth}{.5\pgfphysicalheight}%
}%
The following hoptionsi may be set:
• logical pages=hlogical pagesi specified how many logical pages there are, in total. These are
numbered 1 to hlogical pagesi.
• first logical shipout=hfirsti. See the next option. By default, hfirsti is 1.
• last logical shipout=hlasti. Together with the previous option, these two options define an
interval of pages inside the range 1 to hlogical pagesi. Only this range is used to store the pages
that are shipped out by TEX. This means that after a physical shipout has just occurred (or at
the beginning), the first time TEX wishes to perform a shipout, the page to be shipped out is
stored in logical page hfirsti. The next time TEX performs a shipout, the page is stored in logical
page hfirsti + 1 and so on, until the logical page hlasti is also filled. Once this happens, a physical
shipout occurs and the process starts once more.
Note that logical pages that lie outside the interval between hfirsti and hlasti are filled only indirectly or when special commands are used.
By default, hlasti equals hlogical pagesi.
• current logical shipout=hcurrenti changes an internal counter such that TEX’s next logical
shipout will be stored in logical page hcurrenti.
This option can be used to “warp” the logical page filling mechanism to a certain page. You can
both skip logical pages and overwrite already filled logical pages. After the logical page hcurrenti
has been filled, the internal counter is incremented normally as if the logical page hcurrenti had
been “reached” normally. If you specify a hcurrenti larger than hlasti, a physical shipout will occur
after the logical page hcurrenti has been filled.
916
• physical height=hheighti specifies the height of the physical pages. This height is typically
different from the normal \paperheight, which is used by TEX for its typesetting and page breaking
purposes.
• physical width=hwidthi specifies the physical width.
\pgfpageslogicalpageoptions{hlogical page number i}{hoptionsi}
This command is used to specify where the logical page number hlogical page number i will be placed on
the physical page. In addition, this command can be used to install additional “code” to be executed
when this page is put on the physical page.
The number hlogical page number i should be between 1 and hlogical pagesi, which has previously been
installed using the \pgfpagesphysicalpageoptions command.
The following hoptionsi may be given:
• center=hpgf pointi specifies the center of the logical page inside the physical page as a pgf-point.
The origin of the coordinate system of the physical page is at the lower left corner.
\pgfpageslogicalpageoptions{1}
{% center logical page on middle of left side
center=\pgfpoint{.25\pgfphysicalwidth}{.5\pgfphysicalheight}%
resized width=.5\pgfphysicalwidth,%
resized height=\pgfphysicalheight,%
}
• resized width=hsizei specifies the width that the logical page should have at most on the physical
page. To achieve this width, the pages is scaled down appropriately or more. The “or more” part
can happen if the resize height option is also used. In this case, the scaling is chosen such that
both the specified height and width are met. The aspect ratio of a logical page is not modified.
• resized height=hheighti specifies the maximum height of the logical page.
• original width=hwidthi specifies the width the TEX “thinks” that the logical page has. This width
is \paperwidth at the point of invocation, by default. Note that setting this width to something
different from \paperwidth does not change the \pagewidth during TEX’s typesetting. You have
to do that yourself.
You need this option only for special logical pages that have a height or width different from the
normal one and for which you will (later on) set these sizes yourself.
• original height=hheighti works like original width.
• scale=hfactor i scales the page by at least the given hfactor i. A hfactor i of 0.5 will half the size
of the page, a factor or 2 will double the size. “At least” means that if options like resize height
are given and if the scaling required to meet that option is less than hfactor i, that other scaling is
used instead.
• xscale=hfactor i scales the logical page along the x-axis by the given hfactor i. This scaling is done
independently of any other scaling. Mostly, this option is useful for a factor of -1, which flips the
page along the y-axis. The aspect ratio is not kept.
• yscale=hfactor i works like xscale, only for the y-axis.
• rotation=hdegreei rotates the page by hdegreei around its center. Use a degree of 90 or -90 to go
from portrait to landscape and back. The rotation need not be a multiple of 90.
• copy from=hlogical page number i. Normally, after a physical shipout has occurred, all logical pages
are voided in a loop. However, if this option is given, the current logical page is filled with the
contents of the old logical page number hlogical page number i.
Example: Have logical page 2 retain its contents:
\pgfpageslogicalpageoptions{2}{copy from=2}
Example: Let logical page 2 show what logical page 1 showed on the just-shipped-out physical
page:
\pgfpageslogicalpageoptions{2}{copy from=1}
917
• border shrink=hsizei specifies an additional reduction of the size to which the page is page is
scaled.
• border code=hcodei. When this option is given, the hcodei is executed before the page box
is inserted with a path preinstalled that is a rectangle around the current logical page. Thus,
setting hcodei to \pgfstroke draws a rectangle around the logical page. Setting hcodei to
\pgfsetlinewidth{3pt}\pgfstroke results in a thick (ugly) frame. Adding dashes and filling
can result in arbitrarily funky and distracting borders.
You can also call \pgfdiscardpath and add your own path construction code (for example to paint
a rectangle with rounded corners). The coordinate system is set up in such a way that a rectangle
starting at the origin and having the height and width of TEX-box 0 will result in a rectangle filling
exactly the logical page currently being put on the physical page. The logical page is inserted after
these commands have been executed.
Example: Add a rectangle around the page:
\pgfpageslogicalpageoptions{1}{border code=\pgfstroke}
• corner width=hsizei adds black “rounded corners” to the page. See the description of the predefined layout rounded corners on page 914.
85.4
Creating Logical Pages
Logical pages are created whenever TEX thinks that a page is full and performs a \shipout command. This
will cause pgfpages to store the box that was supposed to be shipped out internally until enough logical
pages have been collected such that a physical shipout can occur.
Normally, whenever a logical shipout occurs, that current page is stored in logical page number hcurrent
logical pagei. This counter is then incremented, until it is larger than hlast logical shipouti. You can, however,
directly change the value of hcurrent logical pagei by calling \pgfpagesphysicalpageoptions.
Another way to set the contents of a logical page is to use the following command:
\pgfpagesshipoutlogicalpage{hnumber i}hbox i
This command sets to logical page hnumber i to hbox i. The hbox i should be the code of a TEX box
command. This command does not influence the counter hcurrent logical pagei and does not cause a
physical shipout.
\pgfpagesshipoutlogicalpage{0}\vbox{Hi!}
This command can be used to set the contents of logical pages that are normally not filled.
The final way of setting a logical page is using the following command:
\pgfpagescurrentpagewillbelogicalpage{hnumber i}
When the current TEX page has been typeset, it will be become the given logical page hnumber i. This
command “interrupts” the normal order of logical pages, that is, it behaves like the previous command
and does not update the hcurrent logical pagei counter.
\pgfpagesuselayout{two screens with optional second}
...
Text for main page.
\clearpage
\pgfpagescurrentpagewillbelogicalpage{2}
Text that goes to second page
\clearpage
Text for main page.
918
86
Extended Color Support
This section documents the package xxcolor, which is currently distributed as part of pgf. This package
extends the xcolor package, written by Uwe Kern, which in turn extends the color package. I hope that
the commands in xxcolor will some day migrate to xcolor, such that this package becomes superfluous.
The main aim of the xxcolor package is to provide an environment inside which all colors are “washed
out” or “dimmed.” This is useful in numerous situations and must typically be achieved in a roundabout
manner if such an environment is not available.
\begin{colormixin}{hmix-in specificationi}
henvironment contentsi
\end{colormixin}
The mix-in specification is applied to all colors inside the environment. At the beginning of the environment, the mix-in is applied to the current color, i. e., the color that was in effect before the environment
started. A mix-in specification is a number between 0 and 100 followed by an exclamation mark and a
color name. When a \color command is encountered inside a mix-in environment, the number states
what percentage of the desired color should be used. The rest is “filled up” with the color given in the
mix-in specification. Thus, a mix-in specification like 90!blue will mix in 10% of blue into everything,
whereas 25!white will make everything nearly white.
Red text,washed-out
red text, washed-out
blue text, dark
washed-out blue text,
dark washed-out green
text, back to
washed-out blue
text,and back to red.
\begin{minipage}{3.5cm}\raggedright
\color{red}Red text,%
\begin{colormixin}{25!white}
washed-out red text,
\color{blue} washed-out blue text,
\begin{colormixin}{25!black}
dark washed-out blue text,
\color{green} dark washed-out green text,%
\end{colormixin}
back to washed-out blue text,%
\end{colormixin}
and back to red.
\end{minipage}%
Note that the environment only changes colors that have been installed using the standard LATEX \color
command. In particular, the colors in images are not changed. There is, however, some support offered by
the commands \pgfuseimage and \pgfuseshading. If the first command is invoked inside a colormixin
environment with the parameter, say, 50!black on an image with the name foo, the command will first
check whether there is also a defined image with the name foo.!50!black. If so, this image is used
instead. This allows you to provide a different image for this case. If you nest colormixin environments,
the different mix-ins are all appended. For example, inside the inner environment of the above example,
\pgfuseimage{foo} would first check whether there exists an image named foo.!25!white!25!black.
\colorcurrentmixin
Expands to the current accumulated mix-in. Each nesting of a colormixin adds a mix-in to this list.
!75!white should be “!75!white”
!75!black!75!white should be “!75!black!75!white”
!50!white!75!black!75!white should be “!50!white!75!black!75!white”
\begin{minipage}{\linewidth-6pt}\raggedright
\begin{colormixin}{75!white}
\colorcurrentmixin\ should be “!75!white”\par
\begin{colormixin}{75!black}
\colorcurrentmixin\ should be “!75!black!75!white”\par
\begin{colormixin}{50!white}
\colorcurrentmixin\ should be “!50!white!75!black!75!white”\par
\end{colormixin}
\end{colormixin}
\end{colormixin}
\end{minipage}
919
87
Parser Module
\usepgfmodule{parser}
\usepgfmodule[parser]
% LATEX and plain TEX and pure pgf
% ConTEXt and pure pgf
This module defines some commands for creating a simple letter-by-letter parser.
This module provides commands for defining a parser that scans some given text letter-by-letter. For
each letter, some code is executed and, possibly a state-switch occurs. The parsing process ends when a final
state has been reached.
\pgfparserparse{hparser namei}htexti
This command is used to parse the htexti using the (previously defined) parser named hparser namei.
The htexti is not contained in curly braces, rather it is all the text that follows. The end of the text is
determined implicitly, namely when the final state of the parser has been reached.
The parser works as follows: At any moment, it is in a certain state, initially this state is called initial.
Then, the first letter of the htexti is examined (using the \futurlet command). For each possible state
and each possible letter, some action code is stored in the parser in a table. This code is then executed.
This code may, but need not, trigger a state switch, causing a new state to be set. The parser then
moves on to the next character of the text and repeats the whole procedure, unless it is in the state
final, which causes the parsing process to stop immediately.
In the following example, the parser counts the number of a’s in the text, ignoring any b’s. The htexti
ends with the first c.
cccThere are 9 a’s.
\newcount\mycount
\pgfparserdef{myparser}{initial}{the letter a}
{\advance\mycount by 1\relax}
\pgfparserdef{myparser}{initial}{the letter b}
{} % do nothing
\pgfparserdef{myparser}{initial}{the letter c}
{\pgfparserswitch{final}}% done!
\pgfparserparse{myparser}aabaabababbbbbabaabcccc
There are \the\mycount\ a’s.
\pgfparserdef{hparser namei}{hstatei}{hsymbol meaningi}{hactioni}
This command should be used repeatedly to define a parser named hparser namei. With a call to this
command you specify that the hparser namei should do the following: When it is in state hstatei and
reads the letter hsymbol meaningi, perform the code stored in hactioni.
The hsymbol meaningi must be the text that results from applying the TEX command \meaning to
the given character. For instance, \meaning a yields the letter a, while \meaning 1 yields the
character 1. A space yields blank space.
Inside the hactioni you can perform almost any kind of code. This code will not be surrounded by a
scope, so its effect persists after the parsing is done. However, each time after the hactioni is executed,
control goes back to the parser. You should not launch a parser inside the hactioni code, unless you put
it in a scope.
When you set the hstatei to all, the state hactioni is performed in all states as a fallback, whenever
hsymbol meaningi is encountered. This means that when you do not specify anything explicitly for a
state and a letter, but you do specify something for all and this letter, then the specified hactioni will
be used.
When the parser encounters a letter for which nothing is specified in the current state (neither directly
nor indirectly via all), an error occurs.
\pgfparserswitch{hstatei}
This command can be called inside the action code of a parser to cause a state switch to hstatei.
920
Part VIII
Mathematical and Object-Oriented Engines
by Mark Wibrow and Till Tantau
pgf comes with two useful engines: One for doing mathematics, one for doing object-oriented programming.
Both engines can be used independently of the main pgf.
The job of the mathematical engine is to support mathematical operations like addition, subtraction,
multiplication and division, using both integers and non-integers, but also functions such as square-roots,
sine, cosine, and generate pseudo-random numbers. Mostly, you will use the mathematical facilities of pgf
indirectly, namely when you write a coordinate like (5cm*3,6cm/4), but the mathematical engine can also
be used independently of pgf and Tik Z.
The job of the object-oriented engine is to support simple object-oriented programming in TEX. It allows
the definition of classes (without inheritance), methods, attributes and objects.
\pgfmathsetseed{1}
\foreach \col in {black,red,green,blue}
{
\begin{tikzpicture}[x=10pt,y=10pt,ultra thick,baseline,line cap=round]
\coordinate (current point) at (0,0);
\coordinate (old velocity) at (0,0);
\coordinate (new velocity) at (rand,rand);
\foreach \i in {0,1,...,100}
{
\draw[\col!\i] (current point)
.. controls ++([scale=-1]old velocity) and
++(new velocity) .. ++(rand,rand)
coordinate (current point);
\coordinate (old velocity) at (new velocity);
\coordinate (new velocity) at (rand,rand);
}
\end{tikzpicture}
}
921
88
Design Principles
pgf needs to perform many computations while typesetting a picture. For this, pgf relies on a mathematical
engine, which can also be used independently of pgf, but which is distributed as part of the pgf package
nevertheless. Basically, the engine provides a parsing mechanism similar to the calc package so that
expressions like 2*3cm+5cm can be parsed; but the pgf engine is more powerful and can be extended and
enhanced.
pgf provides enhanced functionality, which permits the parsing of mathematical operations involving
integers and non-integers with or without units. Furthermore, various functions, including trigonometric
functions and random number generators can also be parsed (see Section 89.1). The calc macros \setlength
and friends have pgf versions which can parse these operations and functions (see Section 89.1). Additionally,
each operation and function has an independent pgf command associated with it (see Section 90), and can
be accessed outside the parser.
The mathematical engine of pgf is implicitly used whenever you specify a number or dimension in a
higher-level macro. For instance, you can write \pgfpoint{2cm+4cm/2}{3cm*sin(30)} or suchlike. However, the mathematical engine can also be used independently of the pgf core, that is, you can also just load
it to get access to a mathematical parser.
88.1
Loading the Mathematical Engine
The mathematical engine of pgf is loaded automatically by pgf, but if you wish to use the mathematical
engine but you do not need pgf itself, you can load the following package:
\usepackage{pgfmath} % LATEX
\input pgfmath.tex
% plain TEX
\usemodule[pgfmath] % ConTEXt
This command will load the mathematical engine of pgf, but not pgf itself. It defines commands like
\pgfmathparse.
88.2
Layers of the Mathematical Engine
Like pgf itself, the mathematical engine is also structured into different layers:
1. The top layer, which you will typically use directly, provides the command \pgfmathparse. This
command parses a mathematical expression and evaluates it.
Additionally, the top layer also defines some additional functions similar to the macros of the calc package for setting dimensions and counters. These macros are just wrappers around the \pgfmathparse
macro.
2. The calculation layer provides macros for performing one specific computation like computing a reciprocal or a multiplication. The parser uses these macros for the actual computation.
3. The implementation layer provides the actual implementations of the computations. These can be
changed (and possibly be made more efficient) without affecting the higher layers.
88.3
Efficiency and Accuracy of the Mathematical Engine
Currently, the mathematical algorithms are all implemented in TEX. This poses some intriguing programming
challenges as TEX is a language for typesetting, rather than for general mathematics, and as with any
programming language, there is a trade-off between accuracy and efficiency. If you find the level of accuracy
insufficient for your purposes, you will have to replace the algorithms in the implementation layer.
All the fancy mathematical “bells-and-whistles” that the parser provides, come with an additional processing cost, and in some instances, such as simply setting a length to 1cm, with no other operations involved,
the additional processing time is undesirable. To overcome this, the following feature is implemented: when
no mathematical operations are required, an expression can be preceded by +. This will bypass the parsing
process and the assignment will be orders of magnitude faster. This feature only works with the macros for
setting registers described in Section 89.1.
\pgfmathsetlength\mydimen{1cm} % parsed
: slower.
\pgfmathsetlength\mydimen{+1cm} % not parsed : much faster.
922
89
Mathematical Expressions
The easiest way of using pgf’s mathematical engine is to provide a mathematical expression given in familiar
infix notation, for example, 1cm+4*2cm/5.5 or 2*3+3*sin(30). This expression can be parsed by the
mathematical engine and the result can be placed in a dimension register, a counter, or a macro.
It should be noted that all calculations must not exceed ±16383.99999 at any point, because the underlying computations rely on TEX dimensions. This means that many of the underlying computations
are necessarily approximate and, in addition, not very fast. TEX is, after all, a typesetting language and
not ideally suited to relatively advanced mathematical operations. However, it is possible to change the
computations as described in Section 91.
In the present section, the high-level macros for parsing an expression are explained first, then the syntax
for expression is explained.
89.1
89.1.1
Parsing Expressions
Commands
The basic command for invoking the parser of pgf’s mathematical engine is the following:
\pgfmathparse{hexpressioni}
This macro parses hexpressioni and returns the result without units in the macro \pgfmathresult.
Example: \pgfmathparse{2pt+3.5pt} will set \pgfmathresult to the text 5.5.
In the following, the special properties of this command are explained. The exact syntax of mathematical
expressions is explained in Sections 89.2 and 89.3.
• The result stored in the macro \pgfmathresult is a decimal without units. This is true regardless
of whether the hexpressioni contains any unit specification. All numbers with units are converted
to points first. See Section 89.1.2 for details on units.
• The parser will recognize TEX registers and box dimensions, so \mydimen, 0.5\mydimen,
\wd\mybox, 0.5\dp\mybox, \mycount\mydimen and so on can be parsed.
• The ε-TeX extensions \dimexpr, \numexpr, \glueexpr, and \muexpr are recognized and evaluated.
The values they result in will be used in the further evaluation, as if you had put \the before them.
• Parenthesis can be used to change the order of the evaluation.
• Various functions are recognized, so it is possible to parse sin(.5*pi r)*60, which means “the
sine of 0.5 times π radians, multiplied by 60”. The argument of functions can be any expression.
• Scientific notation in the form 1.234e+4 is recognized (but the restriction on the range of values
still applies). The exponent symbol can be upper or lower case (i.e., E or e).
• An integer with a zero-prefix (excluding, of course zero itself), is interpreted as an octal number
and is automatically converted to base 10.
• An integer with prefix 0x or 0X is interpreted as a hexadecimal number and is automatically
converted to base 10. Alphabetic digits can be in uppercase or lowercase.
• An integer with prefix 0b or 0B is interpreted as a binary number and is automatically converted
to base 10.
• An expression (or part of an expression) surrounded with double quotes (i.e., the character ") will
not be evaluated. Obviously this should be used with great care.
\pgfmathqparse{hexpressioni}
This macro is similar to \pgfmathparse: it parses hexpressioni and returns the result in the macro
\pgfmathresult. It differs in two respects. Firstly, \pgfmathqparse does not parse functions, scientific
notation, the prefixes for binary octal, or hexadecimal numbers, nor does it accept the special use of
", ? or : characters. Secondly, numbers in hexpressioni must specify a TEX unit (except in such
instances as 0.5\pgf@x), which greatly simplifies the problem of parsing real numbers. As a result of
these restrictions \pgfmathqparse is about twice as fast as \pgfmathparse. Note that the result will
still be a number without units.
923
\pgfmathpostparse
At the end of the parse this command is executed, allowing some custom action to be performed on the
result of the parse. When this command is executed, the macro \pgfmathresult will hold the result
of the parse (as always, without units). The result of the custom action should be used to redefine
\pgfmathresult appropriately. By default, this command is equivalent to \relax. This differs from
previous versions, where, if the parsed expression contained no units, the result of the parse was scaled
according to the value in \pgfmathresultunitscale (which by default was 1).
This scaling can be turned on again using: \let\pgfmathpostparse=\pgfmathscaleresult. Note,
however that by scaling the result, the base conversion functions will not work, and the " character
should not be used to quote parts of an expression.
Instead of the \pgfmathparse macro you can also use wrapper commands, whose usage is very similar
to their cousins in the calc package. The only difference is that the expressions can be any expression that
is handled by \pgfmathparse. For all of the following commands, if hexpressioni starts with +, no parsing
is done and a simple assignment or increment is done using normal TEX assignments or increments. This
will be orders of magnitude faster than calling the parser.
The effect of the following commands is always local to the current TEX scope.
\pgfmathsetlength{hregister i}{hexpressioni}
Basically, this command sets the length of the TEX hregister i to the value specified by hexpressioni.
However, there is some fine print:
First, in case hexpressioni starts with a +, a simple TEX assignment is done. In particular, hregister i
can be a glue register and hexpressioni be something like +1pt plus 1fil and the hregister i will be
assigned the expected value.
Second, when the hexpressioni does not start with +, it is first parsed using \pgfmathparse, resulting
in a (dimensionless) value \pgfmathresult. Now, if the parser encountered the unit mu somewhere in
the expression, it assumes that hregister i is a \muskip register and will try to assign to hregister i the
value \pgfmathresult followed by mu. Otherwise, in case mu was not encountered, it is assumed that
hregister i is a dimension register or a glue register and we assign \pgfmathresult followed by pt to it.
The net effect of the above is that you can write things like
13.0mu
13.0pt
13.0pt
\muskipdef\mymuskip=0
\pgfmathsetlength{\mymuskip}{1mu+3*4mu} \the\mymuskip
\dimendef\mydimen=0
\pgfmathsetlength{\mydimen}{1pt+3*4pt}
\skipdef\myskip=0
\pgfmathsetlength{\myskip}{1pt+3*4pt}
\the\mydimen
\the\myskip
One thing that will not work is \pgfmathsetlength{\myskip}{1pt plus 1fil} since the parser does
not support fill’s. You can, however, use the + notation in this case:
1.0pt plus 1.0fil
\skipdef\myskip=0
\pgfmathsetlength{\myskip}{+1pt plus 1fil}
\the\myskip
\pgfmathaddtolength{hregister i}{hexpressioni}
Adds the value of hexpressioni to the TEX hregister i. All of the special consideration mentioned for
\pgfmathsetlength also apply here in the same way.
\pgfmathsetcount{hcount register i}{hexpressioni}
Sets the value of the TEX hcount register i, to the truncated value specified by hexpressioni.
\pgfmathaddtocount{hcount register i}{hexpressioni}
Adds the truncated value of hexpressioni to the TEX hcount register i.
\pgfmathsetcounter{hcounter i}{hexpressioni}
Sets the value of the LATEX hcounter i to the truncated value specified by hexpressioni.
924
\pgfmathaddtocounter{hcounter i}{hexpressioni}
Adds the truncated value of hexpressioni to hcounter i.
\pgfmathsetmacro{hmacroi}{hexpressioni}
Defines hmacroi as the value of hexpressioni. The result is a decimal without units.
\pgfmathsetlengthmacro{hmacroi}{hexpressioni}
Defines hmacroi as the value of hexpressioni LATEX in points.
\pgfmathtruncatemacro{hmacroi}{hexpressioni}
Defines hmacroi as the truncated value of hexpressioni.
89.1.2
Considerations Concerning Units
As was explained earlier, the parser commands like \pgfmathparse will always return a result without units
in it and all dimensions that have a unit like 10pt or 1in will first be converted to TEX points (pt) and,
then, the unit is dropped.
Sometimes it is useful, nevertheless, to find out whether an expression or not. For this, you can use the
following commands:
\ifpgfmathunitsdeclared
After a call of \pgfmathparse this if will be true exactly if some unit was encountered in the expression.
It is always set globally in each call.
Note that any “mentioning” of a unit inside an expression will set this TEX-if to true. In particular,
even an expressionlike 2pt/1pt, which arguably should be considered “scalar” or “unit-free” will still
have this TEX-if set to true. However, see the scalar function for a way to change this.
scalar(value)
\pgfmathscalar{value}
This function is the identity function on its input, but it will reset the TEX-if \ifpgfmathunitsdeclared.
Thus, it can be used to indicate that the given hvaluei should be considered as a “scalar” even when it
contains units; but note that it will work even when the hvaluei is a string or something else. The only
effect of this function is to clear the unit declaration.
0.5 without unit
\pgfmathparse{scalar(1pt/2pt)} \pgfmathresult\
\ifpgfmathunitsdeclared with \else without \fi unit
Note, however, that this command (currently) really just clears the TEX-if as the input is scanned from
left-to-right. Thus, even if there is a use of a unit before the scalar function is used, the TEX-if will be
cleared:
2.0 without unit
\pgfmathparse{1pt+scalar(1pt)} \pgfmathresult\
\ifpgfmathunitsdeclared with \else without \fi unit
The other way round, a use of a unit after the scalar function will set the units once more.
2.0 with unit
\pgfmathparse{scalar(1pt)+1pt} \pgfmathresult\
\ifpgfmathunitsdeclared with \else without \fi unit
For these reasons, you should use the function only on the outermost level of an expression.
A typical use of this function is the following:
A
B
D
C
\tikz{
\coordinate["$A$"]
(A) at (2,2);
\coordinate["$B$" below] (B) at (0,0);
\coordinate["$C$" below] (C) at (3,0);
\draw (A) -- (B) -- (C) -- cycle;
\path
let \p1 =($(A)-(B)$), \p2 =($(A)-(C)$),
\n1 = {veclen(\x1,\y1)}, \n2 = {veclen(\x2,\y2)}
in coordinate ["$D$" below] (D) at ($ (B)!scalar(\n1/(\n1+\n2))!(C) $);
\draw (A) -- (D);
}
925
A special kind of units are TEX’s “math units” (mu). It will be treated as if pt had been used, but you
can check whether an expression contained a math unit using the following:
\ifpgfmathmathunitsdeclared
This TEX-if is similar to \ifpgfmathunitsdeclared, but it is only set when the unit mu is encountered
at least once. In this case, \ifpgfmathunitsdeclared will also be set to true. The scalar function
has no effect on this TEX-if.
89.2
Syntax for Mathematical Expressions: Operators
The syntax for the expressions recognized by \pgfmathparse and friends is rather straightforward. Let us
start with the operators.
The following operators (presented in the context in which they are used) are recognized:
x +y
(infix operator; uses the add function)
Adds x to y.
x -y
(infix operator; uses the subtract function)
Subtracts y from x .
(prefix operator; uses the neg function)
-x
Reverses the sign of x .
x *y
Multiples x by y.
(infix operator; uses the multiply function)
x /y
(infix operator; uses the divide function)
Divides x by y. An error will result if y is 0, or if the result of the division is too big for the mathematical
engine. Please remember when using this command that accurate (and reasonably quick) division of
real numbers that are not integers is particularly tricky in TEX.
x ^y
(infix operator; uses the pow function)
Raises x to the power y.
x!
(postfix operator; uses the factorial function)
Calculates the factorial of x .
xr
(postfix operator; uses the deg function)
Converts x to degrees (x is assumed to be in radians). This operator has the same precedence as
multiplication.
x ?y :z
(conditional operators; use the ifthenelse function)
? and : are special operators which can be used as a shorthand for if x then y else z inside the
parser. The expression x is taken to be true if it evaluates to any non-zero value.
x == y
(infix operator; uses the equal function)
Returns 1 if x =y, 0 otherwise.
x >y
(infix operator; uses the greater function)
Returns 1 if x >y, 0 otherwise.
x = y
(infix operator; uses the notless function)
Returns 1 if x ≥y, 0 otherwise.
926
x <= y
(infix operator; uses the notgreater function)
Returns 1 if x ≤y, 0 otherwise.
x && y
(infix operator; uses the and function)
Returns 1 if both x and y evaluate to some non-zero value. Both arguments are evaluated.
x || y
(infix operator; uses the or function)
Returns 1 if either x or y evaluate to some non-zero value.
(prefix operator; uses the not function)
!x
Returns 1 if x evaluates to zero, 0 otherwise.
(group operators)
(x )
These operators act in the usual way, that is, to control the order in which operators are executed, for
example, (1+2)*3. This includes the grouping of arguments for functions, for example, sin(30*10) or
mod(72,3) (the comma character is also treated as an operator).
Parentheses for functions with one argument are not always necessary, sin 30 (note the space) is
the same as sin(30). However, functions have the highest precedence so, sin 30*10 is the same as
sin(30)*10.
(array operators)
{x }
These operators are used to process array-like structures (within an expression these characters do not
act like TEX grouping tokens). The harray specificationi consists of comma separated elements, for
example, {1, 2, 3, 4, 5}. Each element in the array will be evaluated as it is parsed, so expressions
can be used. In addition, an element of an array can be an array itself, allowing multiple dimension
arrays to be simulated: {1, {2,3}, {4,5}, 6}. When storing an array in a macro, do not forget the
surrounding braces: \def\myarray{{1,2,3}} not \def\myarray{1,2,3}.
1, two, 3.0, IV, cinq, sechs, 7.0,
\def\myarray{{1,"two",2+1,"IV","cinq","sechs",sin(\i*5)*14}}
\foreach \i in {0,...,6}{\pgfmathparse{\myarray[\i]}\pgfmathresult, }
(array access operators; use the array function)
[x ]
[ and ] are two operators used in one particular circumstance: to access an array (specified using the {
and } operators) using the index x . Indexing starts from zero, so, if the index is greater than, or equal
to, the number of values in the array, an error will occur, and zero will be returned.
-9.0
\def\myarray{{7,-3,4,-9,11}}
\pgfmathparse{\myarray[3]} \pgfmathresult
If the array is defined to have multiple dimensions, then the array access operators can be immediately
repeated.
1 0 0
0 1 0
0 0 1
\def\print#1{\pgfmathparse{#1}\pgfmathresult}
\def\identitymatrix{{{1,0,0},{0,1,0},{0,0,1}}}
\tikz[x=0.5cm,y=0.5cm]\foreach \i in {0,1,2} \foreach \j in {0,1,2}
\node at (\j,-\i) [anchor=base] {\print{\identitymatrix[\i][\j]}};
(group operators)
"x "
These operators are used to quote x . However, as every expression is expanded with \edef before it is
parsed, macros (e.g., font commands like \tt or \Huge) may need to be “protected” from this expansion
(e.g., \noexpand\Huge). Ideally, you should avoid such macros anyway. Obviously, these operators
should be used with great care as further calculations are unlikely to be possible with the result.
5 is
Bigger than 0.
5 is
smaller than 10.
\def\x{5}
\foreach \y in {0,10}{
\pgfmathparse{\x > \y ? "\noexpand\Large Bigger" : "\noexpand\tiny smaller"}
\x\ is \pgfmathresult\ than \y.
}
927
89.3
Syntax for Mathematical Expressions: Functions
The following functions are recognized:
abs
acos
add
and
array
asin
atan
atan2
bin
ceil
cos
cosec
cosh
cot
deg
depth
div
divide
e
equal
factorial
false
floor
frac
gcd
greater
height
hex
Hex
int
ifthenelse
iseven
isodd
isprime
less
ln
log10
log2
max
min
mod
Mod
multiply
neg
not
notequal
notgreater
notless
oct
or
pi
pow
rad
rand
random
real
rnd
round
scalar
sec
sign
sin
sinh
sqrt
subtract
tan
tanh
true
veclen
width
Each function has a pgf command associated with it (which is also shown with the function below). In
general, the command is simply the name of the function prefixed with \pgfmath, for example, \pgfmathadd,
but there are some notable exceptions.
89.3.1
Basic arithmetic functions
add(x ,y)
\pgfmathadd{x }{y}
Adds x and y.
81.0
\pgfmathparse{add(75,6)} \pgfmathresult
subtract(x ,y)
\pgfmathsubtract{x }{y}
Subtract x from y.
69.0
\pgfmathparse{subtract(75,6)} \pgfmathresult
neg(x )
\pgfmathneg{x }
This returns −x .
-50.0
\pgfmathparse{neg(50)} \pgfmathresult
multiply(x ,y)
\pgfmathmultiply{x }{y}
Multiply x by y.
450.0
\pgfmathparse{multiply(75,6)} \pgfmathresult
divide(x ,y)
\pgfmathdivide{x }{y}
Divide x by y.
12.5
\pgfmathparse{divide(75,6)} \pgfmathresult
div(x ,y)
928
\pgfmathdiv{x }{y}
Divide x by y and round to the nearest integer
8
\pgfmathparse{div(75,9)} \pgfmathresult
factorial(x )
\pgfmathfactorial{x }
Return x !.
120.0
\pgfmathparse{factorial(5)} \pgfmathresult
sqrt(x )
\pgfmathsqrt{x }
√
Calculates x .
3.16227
93.62388
\pgfmathparse{sqrt(10)} \pgfmathresult
\pgfmathparse{sqrt(8765.432)}
\pgfmathresult
pow(x ,y)
\pgfmathpow{x }{y}
Raises x to the power y. For greatest accuracy, y should be an integer. If y is not an integer, the actual
calculation will be an approximation of eyln(x) .
128.0
\pgfmathparse{pow(2,7)} \pgfmathresult
e
\pgfmathe
Returns the value 2.718281828.
3.62685
\pgfmathparse{(e^2-e^-2)/2} \pgfmathresult
exp(x )
\pgfmathexp{x }
Maclaurin series for ex .
2.71825
10.38083
\pgfmathparse{exp(1)} \pgfmathresult
\pgfmathparse{exp(2.34)} \pgfmathresult
ln(x )
\pgfmathln{x }
An approximation for ln(x ). This uses an algorithm of Rouben Rostamian, and coefficients suggested
by Alain Matthes.
2.30257
\pgfmathparse{ln(10)} \pgfmathresult
4.99997
\pgfmathparse{ln(exp(5))} \pgfmathresult
log10(x )
\pgfmathlogten{x }
An approximation for log10 (x ).
1.99997
\pgfmathparse{log10(100)} \pgfmathresult
929
log2(x )
\pgfmathlogtwo{x }
An approximation for log2 (x ).
6.99994
\pgfmathparse{log2(128)} \pgfmathresult
abs(x )
\pgfmathabs{x }
Evaluates the absolute value of x.
5.0
-12.0
\pgfmathparse{abs(-5)} \pgfmathresult
\pgfmathparse{-abs(4*-3)} \pgfmathresult
mod(x ,y)
\pgfmathmod{x }{y}
This evaluates x modulo y, using truncated division. The sign of the result is the same as the sign of
2.0
-10.0
x
y.
\pgfmathparse{mod(20,6)} \pgfmathresult
\pgfmathparse{mod(-100,30)} \pgfmathresult
Mod(x ,y)
\pgfmathMod{x }{y}
This evaluates x modulo y, using floored division. The sign of the result is never negative.
20.0
\pgfmathparse{Mod(-100,30)} \pgfmathresult
sign(x )
\pgfmathsign{x }
Returns the sign of x.
89.3.2
-1
\pgfmathparse{sign(-5)} \pgfmathresult
0
\pgfmathparse{sign(0)} \pgfmathresult
1
\pgfmathparse{sign(5)} \pgfmathresult
Rounding functions
round(x )
\pgfmathround{x }
Rounds x to the nearest integer. It uses “asymmetric half-up” rounding. So 1.5 is rounded to 2, but
-1.5 is rounded to -2 (not -1).
2.0
33.0
\pgfmathparse{round(32.5/17)} \pgfmathresult
\pgfmathparse{round(398/12)} \pgfmathresult
floor(x )
930
\pgfmathfloor{x }
Rounds x down to the nearest integer.
1.0
\pgfmathparse{floor(32.5/17)} \pgfmathresult
33.0
\pgfmathparse{floor(398/12)} \pgfmathresult
-34.0
\pgfmathparse{floor(-398/12)} \pgfmathresult
ceil(x )
\pgfmathceil{x }
Rounds x up to the nearest integer.
2.0
\pgfmathparse{ceil(32.5/17)} \pgfmathresult
34.0
\pgfmathparse{ceil(398/12)} \pgfmathresult
-33.0
\pgfmathparse{ceil(-398/12)} \pgfmathresult
int(x )
\pgfmathint{x }
Returns the integer part of x .
1
\pgfmathparse{int(32.5/17)} \pgfmathresult
frac(x )
\pgfmathfrac{x }
Returns the fractional part of x .
0.91176
\pgfmathparse{frac(32.5/17)} \pgfmathresult
real(x )
\pgfmathreal{x }
Ensures x contains a decimal point.
4.0
89.3.3
\pgfmathparse{real(4)} \pgfmathresult
Integer arithmetics functions
gcd(x ,y)
\pgfmathgcd{x }{y}
Computes the greatest common divider of x and y.
14
\pgfmathparse{gcd(42,56)} \pgfmathresult
isodd(x )
\pgfmathisodd{x }
Returns 1 if the integer part of x is odd. Otherwise, returns 0.
0,1
\pgfmathparse{isodd(2)} \pgfmathresult,
\pgfmathparse{isodd(3)} \pgfmathresult
iseven(x )
931
\pgfmathiseven{x }
Returns 1 if the integer part of x is even. Otherwise, returns 0.
1,0
\pgfmathparse{iseven(2)} \pgfmathresult,
\pgfmathparse{iseven(3)} \pgfmathresult
isprime(x )
\pgfmathisprime{x }
Returns 1 if the integer part of x is prime. Otherwise, returns 0.
0,1,1,0
89.3.4
\pgfmathparse{isprime(1)} \pgfmathresult,
\pgfmathparse{isprime(2)} \pgfmathresult,
\pgfmathparse{isprime(31)} \pgfmathresult,
\pgfmathparse{isprime(64)} \pgfmathresult
Trigonometric functions
pi
\pgfmathpi
Returns the value π = 3.141592654.
3.141592654
179.99962
\pgfmathparse{pi} \pgfmathresult
\pgfmathparse{pi r} \pgfmathresult
rad(x )
\pgfmathrad{x }
Convert x to radians. x is assumed to be in degrees.
1.57079
\pgfmathparse{rad(90)} \pgfmathresult
deg(x )
\pgfmathdeg{x }
Convert x to degrees. x is assumed to be in radians.
269.999
\pgfmathparse{deg(3*pi/2)} \pgfmathresult
sin(x )
\pgfmathsin{x }
Sine of x . By employing the r operator, x can be in radians.
0.86603
\pgfmathparse{sin(60)} \pgfmathresult
0.86601
\pgfmathparse{sin(pi/3 r)} \pgfmathresult
cos(x )
\pgfmathcos{x }
Cosine of x . By employing the r operator, x can be in radians.
0.5
0.49998
\pgfmathparse{cos(60)} \pgfmathresult
\pgfmathparse{cos(pi/3 r)} \pgfmathresult
tan(x )
932
\pgfmathtan{x }
Tangent of x . By employing the r operator, x can be in radians.
1.00005
1.0
\pgfmathparse{tan(45)} \pgfmathresult
\pgfmathparse{tan(2*pi/8 r)} \pgfmathresult
sec(x )
\pgfmathsec{x }
Secant of x . By employing the r operator, x can be in radians.
1.41429
\pgfmathparse{sec(45)} \pgfmathresult
cosec(x )
\pgfmathcosec{x }
Cosecant of x . By employing the r operator, x can be in radians.
2.0
\pgfmathparse{cosec(30)} \pgfmathresult
cot(x )
\pgfmathcot{x }
Cotangent of x . By employing the r operator, x can be in radians.
3.73215
\pgfmathparse{cot(15)} \pgfmathresult
asin(x )
\pgfmathasin{x }
Arcsine of x . The result is in degrees and in the range ±90◦ .
44.99945
\pgfmathparse{asin(0.7071)} \pgfmathresult
acos(x )
\pgfmathacos{x }
Arccosine of x in degrees. The result is in the range [0◦ , 180◦ ].
60.0
\pgfmathparse{acos(0.5)} \pgfmathresult
atan(x )
\pgfmathatan{x }
Arctangent of x in degrees.
45.0
\pgfmathparse{atan(1)} \pgfmathresult
atan2(y,x )
\pgfmathatantwo{y}{x }
Arctangent of y ÷ x in degrees. This also takes into account the quadrants.
-53.13011
\pgfmathparse{atan2(-4,3)} \pgfmathresult
933
(no default, initially deg)
/pgf/trig format=deg|rad
Allows to define whether trigonometric math functions (i.e. all in this subsection) operate with degrees
or with radians.
0.7071
0.0
\pgfmathparse{cos(45)} \pgfmathresult
\pgfkeys{/pgf/trig format=rad}
\pgfmathparse{cos(pi/2)} \pgfmathresult
The initial configuration trig format=deg is the base of pgf: almost all of it is based on degrees.
Specifying trig format=rad is most useful for data visualization where the angles are typically given
in radians. However, it is applied to all trigonometric functions for which the option applies, including
any drawing instructions which operate on angles.
\begin{tikzpicture}
\draw[-stealth]
(0:1) -- (45:1) -- (90:1) -- (135:1) -- (180:1);
\draw[-stealth,trig format=rad,red]
(pi:1) -- (5/4*pi:1) -- (6/4*pi:1) -- (7/4*pi:1) -- (2*pi:1);
\end{tikzpicture}
Warning: At the time of this writing, this feature is “experimental”. Please handle it with care: there
may be path instructions or libraries in pgf which rely on trig format=deg. The intented usage of
trig format=rad is for local scopes – and as option for data visualization.
89.3.5
Comparison and logical functions
equal(x ,y)
\pgfmathequal{x }{y}
This returns 1 if x = y and 0 otherwise.
1
\pgfmathparse{equal(20,20)} \pgfmathresult
greater(x ,y)
\pgfmathgreater{x }{y}
This returns 1 if x > y and 0 otherwise.
0
\pgfmathparse{greater(20,25)} \pgfmathresult
less(x ,y)
\pgfmathless{x }{y}
This returns 1 if x < y and 0 otherwise.
0
\pgfmathparse{greater(20,25)} \pgfmathresult
notequal(x ,y)
\pgfmathnotequal{x }{y}
This returns 0 if x = y and 1 otherwise.
1
\pgfmathparse{notequal(20,25)} \pgfmathresult
notgreater(x ,y)
\pgfmathnotgreater{x }{y}
This returns 1 if x ≤ y and 0 otherwise.
1
\pgfmathparse{notgreater(20,25)} \pgfmathresult
934
notless(x ,y)
\pgfmathnotless{x }{y}
This returns 1 if x ≥ y and 0 otherwise.
0
\pgfmathparse{notless(20,25)} \pgfmathresult
and(x ,y)
\pgfmathand{x }{y}
This returns 1 if x and y both evaluate to non-zero values. Otherwise 0 is returned.
0
\pgfmathparse{and(5>4,6>7)} \pgfmathresult
or(x ,y)
\pgfmathor{x }{y}
This returns 1 if either x or y evaluate to non-zero values. Otherwise 0 is returned.
0
\pgfmathparse{and(5>4,6>7)} \pgfmathresult
not(x )
\pgfmathnot{x }
This returns 1 if x = 0, otherwise 0.
0
\pgfmathparse{not(true)} \pgfmathresult
ifthenelse(x ,y,z )
\pgfmathifthenelse{x }{y}{z }
This returns y if x evaluates to some non-zero value, otherwise z is returned.
no
\pgfmathparse{ifthenelse(5==4,"yes","no")} \pgfmathresult
true
\pgfmathtrue
This evaluates to 1.
yes
\pgfmathparse{true ? "yes" : "no"} \pgfmathresult
false
\pgfmathfalse
This evaluates to 0.
no
89.3.6
\pgfmathparse{false ? "yes" : "no"} \pgfmathresult
Pseudo-random functions
rnd
\pgfmathrnd
Generates a pseudo-random number between 0 and 1 with a uniform distribution.
0.35255, 0.52394, 0.9081, 0.07314, 0.01263, 0.86674, 0.42123, 0.63577, 0.0252, 0.1887,
\foreach \x in {1,...,10}{\pgfmathparse{rnd}\pgfmathresult, }
rand
935
\pgfmathrand
Generates a pseudo-random number between −1 and 1 with a uniform distribution.
-0.171, -0.6502, 0.80553, 0.81995, 0.18893, 0.25227, 0.83768, -0.39989, -0.43884, 0.51918,
\foreach \x in {1,...,10}{\pgfmathparse{rand}\pgfmathresult, }
random(x ,y)
\pgfmathrandom{x ,y}
This function takes zero, one or two arguments. If there are zero arguments, a uniform random number
between 0 and 1 is generated. If there is one argument x , a random integer between 1 and x is generated.
Finally, if there are two arguments, a random integer between x and y is generated. If there are no
arguments, the pgf command should be called as follows: \pgfmathrandom{}.
0.67236, 0.3279, 0.01428, 0.76451, 0.26901, 0.00323, 0.03891, 0.40141, 0.8682, 0.51057,
\foreach \x in {1,...,10}{\pgfmathparse{random()}\pgfmathresult, }
52, 2, 17, 39, 1, 53, 85, 42, 100, 39,
\foreach \x in {1,...,10}{\pgfmathparse{random(100)}\pgfmathresult, }
619, 426, 467, 758, 569, 493, 674, 626, 614, 400,
\foreach \x in {1,...,10}{\pgfmathparse{random(232,762)}\pgfmathresult, }
89.3.7
Base conversion functions
hex(x )
\pgfmathhex{x }
Convert x (assumed to be an integer in base 10) to a hexadecimal representation, using lower case
alphabetic digits. No further calculation will be possible with the result.
ffff
\pgfmathparse{hex(65535)} \pgfmathresult
Hex(x )
\pgfmathHex{x }
Convert x (assumed to be an integer in base 10) to a hexadecimal representation, using upper case
alphabetic digits. No further calculation will be possible with the result.
FFFF
\pgfmathparse{Hex(65535)} \pgfmathresult
oct(x )
\pgfmathoct{x }
Convert x (assumed to be an integer in base 10) to an octal representation. No further calculation
should be attempted with the result, as the parser can only process numbers converted to base 10.
77
\pgfmathparse{oct(63)} \pgfmathresult
bin(x )
\pgfmathbin{x }
Convert x (assumed to be an integer in base 10) to a binary representation. No further calculation
should be attempted with the result, as the parser can only process numbers converted to base 10.
10111001
\pgfmathparse{bin(185)} \pgfmathresult
936
89.3.8
Miscellaneous functions
min(x1 ,x2 ,...,xn )
\pgfmathmin{x1 ,x2 ,...}{...,xn−1 ,xn }
Return the minimum value from x1 . . . xn . For historical reasons, the command \pgfmathmin takes two
arguments, but each of these can contain an arbitrary number of comma separated values.
-8.0
\pgfmathparse{min(3,4,-2,250,-8,100)} \pgfmathresult
max(x1 ,x2 ,...,xn )
\pgfmathmax{x1 ,x2 ,...}{...,xn−1 ,xn }
Return the maximum value from x1 . . . xn . Again, for historical reasons, the command \pgfmathmax
takes two arguments, but each of these can contain an arbitrary number of comma separated values.
250.0
\pgfmathparse{max(3,4,-2,250,-8,100)} \pgfmathresult
veclen(x ,y)
\pgfmathveclen{x }{y}
p
Calculates (x 2 + y 2 ). This uses a polynomial approximation, based on ideas of Rouben Rostamian
12.99976
\pgfmathparse{veclen(12,5)} \pgfmathresult
array(x ,y)
\pgfmatharray{x }{y}
This accesses the array x at the index y. The array must begin and end with braces (e.g., {1,2,3,4})
and array indexing starts at 0.
17
\pgfmathparse{array({9,13,17,21},2)} \pgfmathresult
The following hyperbolic functions were adapted from code suggested by Martin Heller:
sinh(x )
\pgfmathsinh{x }
The hyperbolic sine of x
0.52103
\pgfmathparse{sinh(0.5)} \pgfmathresult
cosh(x )
\pgfmathcosh{x }
The hyperbolic cosine of x
1.12767
\pgfmathparse{cosh(0.5)} \pgfmathresult
tanh(x )
\pgfmathtanh{x }
The hyperbolic tangent of x
0.462
\pgfmathparse{tanh(0.5)} \pgfmathresult
width("x ")
\pgfmathwidth{"x "}
Return the width of a TEX (horizontal) box containing x . The quote characters are necessary to prevent
x from being parsed. It is important to remember that any expression is expanded with \edef before
being parsed, so any macros (e.g., font commands like \tt or \Huge) will need to be “protected” (e.g.,
\noexpand\Huge is usually sufficient).
78.45306
\pgfmathparse{width("Some Lovely Text")} \pgfmathresult
Note that results of this method are provided in points.
937
height("x ")
\pgfmathheight{"x "}
Return the height of a box containing x .
6.8872
\pgfmathparse{height("Some Lovely Text")} \pgfmathresult
depth("x ")
\pgfmathdepth{"x "}
Returns the depth of a box containing x .
1.94397
\pgfmathparse{depth("Some Lovely Text")} \pgfmathresult
938
90
Additional Mathematical Commands
Instead of parsing and evaluating complex expressions, you can also use the mathematical engine to evaluate
a single mathematical operation. The macros used for many of these computations are listed above in
Section 89.3. pgf also provides some additional commands which are shown below:
90.1
Basic arithmetic functions
In addition to the commands described in Section 89.3.1, the following command is provided:
\pgfmathreciprocal{hx i}
Defines \pgfmathresult as 1 ÷ hx i. This provides greatest accuracy when x is small.
90.2
Comparison and logical functions
In addition to the commands described in Section 89.3.5, the following command was provided by Christian
Feuersänger:
\pgfmathapproxequalto{hx i}{hyi}
Defines \pgfmathresult 1.0 if |hx i−hyi|< 0.0001, but 0.0 otherwise. As a side-effect, the global boolean
\ifpgfmathcomparison will be set accordingly.
90.3
Pseudo-Random Numbers
In addition to the commands described in Section 89.3.6, the following commands are provided:
\pgfmathgeneratepseudorandomnumber
Defines \pgfmathresult as a pseudo-random integer between 1 and 231 − 1. This uses a linear congruency generator, based on ideas of Erich Janka.
\pgfmathrandominteger{hmacroi}{hminimumi}{hmaximumi}
This defines hmacroi as a pseudo-randomly generated integer from the range hminimumi to hmaximumi
(inclusive).
\begin{pgfpicture}
\foreach \x in {1,...,50}{
\pgfmathrandominteger{\a}{1}{50}
\pgfmathrandominteger{\b}{1}{50}
\pgfpathcircle{\pgfpoint{+\a pt}{+\b pt}}{+2pt}
\color{blue!40!white}
\pgfsetstrokecolor{blue!80!black}
\pgfusepath{stroke, fill}
}
\end{pgfpicture}
\pgfmathdeclarerandomlist{hlist namei}{{hitem-1 i}{hitem 2 i}...}
This creates a list of items with the name hlist namei.
\pgfmathrandomitem{hmacroi}{hlist namei}
Select an item from a random list hlist namei. The selected item is placed in hmacroi.
\begin{pgfpicture}
\pgfmathdeclarerandomlist{color}{{red}{blue}{green}{yellow}{white}}
\foreach \a in {1,...,50}{
\pgfmathrandominteger{\x}{1}{85}
\pgfmathrandominteger{\y}{1}{85}
\pgfmathrandominteger{\r}{5}{10}
\pgfmathrandomitem{\c}{color}
\pgfpathcircle{\pgfpoint{+\x pt}{+\y pt}}{+\r pt}
\color{\c!40!white}
\pgfsetstrokecolor{\c!80!black}
\pgfusepath{stroke, fill}
}
\end{pgfpicture}
939
\pgfmathsetseed{hinteger i}
Explicitly sets the seed for the pseudo-random number generator. By default it is set to the value of
\time×\year.
90.4
Base Conversion
pgf provides limited support for conversion between representations of numbers. Currently the numbers
must be positive integers in the range 0 to 231 − 1, and the bases in the range 2 to 36. All digits representing
numbers greater than 9 (in base ten), are alphabetic, but may be upper or lower case.
In addition to the commands described in Section 89.3.7, the following commands are provided:
\pgfmathbasetodec{hmacroi}{hnumber i}{hbasei}
Defines hmacroi as the result of converting hnumber i from base hbasei to base 10. Alphabetic digits can
be upper or lower case.
4223
\pgfmathbasetodec\mynumber{107f}{16} \mynumber
Note that, as usual in TEX, the braces around an argument can be omitted if the argument is just a
single token (a macro name is a single token).
25512
\pgfmathbasetodec\mynumber{33FC}{20} \mynumber
\pgfmathdectobase{hmacroi}{hnumber i}{hbasei}
Defines hmacroi as the result of converting hnumber i from base 10 to base hbasei. Any resulting
alphabetic digits are in lower case.
ffff
\pgfmathdectobase\mynumber{65535}{16} \mynumber
\pgfmathdectoBase{hmacroi}{hnumber i}{hbasei}
Defines hmacroi as the result of converting hnumber i from base 10 to base hbasei. Any resulting
alphabetic digits are in upper case.
FFFF
\pgfmathdectoBase\mynumber{65535}{16} \mynumber
\pgfmathbasetobase{hmacroi}{hnumber i}{hbase-1 i}{hbase-2 i}
Defines hmacroi as the result of converting hnumber i from base hbase-1 i to base hbase-2 i. Alphabetic
digits in hnumber i can be upper or lower case, but any resulting alphabetic digits are in lower case.
db
\pgfmathbasetobase\mynumber{11011011}{2}{16} \mynumber
\pgfmathbasetoBase{hmacroi}{hnumber i}{hbase-1 i}{hbase-2 i}
Defines hmacroi as the result of converting hnumber i from base hbase-1 i to base hbase-2 i. Alphabetic
digits in hnumber i can be upper or lower case, but any resulting alphabetic digits are in upper case.
31B
\pgfmathbasetoBase\mynumber{121212}{3}{12} \mynumber
\pgfmathsetbasenumberlength{hinteger i}
Sets the number of digits in the result of a base conversion to hinteger i. If the result of a conversion
has less digits than this number, it is prefixed with zeros.
00001111
\pgfmathsetbasenumberlength{8}
\pgfmathdectobase\mynumber{15}{2} \mynumber
\pgfmathtodigitlist{hmacroi}{hnumber i}
This command converts hnumber i into a comma-separated list of digits and stores the result in hmacroi.
The {hnumber i} is not parsed before processing.
940
\pgfmathsetbasenumberlength{8}
\begin{tikzpicture}[x=0.25cm, y=0.25cm]
\foreach \n [count=\y] in {0, 60, 102, 102, 126, 102, 102, 102, 0}{
\pgfmathdectobase{\binary}{\n}{2}
\pgfmathtodigitlist{\digitlist}{\binary}
\foreach \digit [count=\x, evaluate={\c=\digit*50+15;}] in \digitlist
\fill [fill=black!\c] (\x, -\y) rectangle ++(1,1);
}
\end{tikzpicture}
90.5
Angle Computations
Unlike the rest of the math engine, which is a “standalone” package, the following commands only work in
conjunction with the core of pgf.
\pgfmathanglebetweenpoints{hpi}{hqi}
Returns the angle of a line from hpi to hqi relative to a line going straight right from hpi.
45.0
\pgfmathanglebetweenpoints{\pgfpoint{1cm}{3cm}}{\pgfpoint{2cm}{4cm}}
\pgfmathresult
\pgfmathanglebetweenlines{hp1 i}{hq1 i}{hp2 i}{hq2 i}
Returns the clockwise angle between a line going through p1 and q1 and a line going through p2 and q2 .
270.0
\pgfmathanglebetweenlines{\pgfpoint{1cm}{3cm}}{\pgfpoint{2cm}{4cm}}
{\pgfpoint{0cm}{1cm}}{\pgfpoint{1cm}{0cm}}
\pgfmathresult
941
91
Customizing the Mathematical Engine
Perhaps you have a desire for some function that pgf does not provide. Perhaps you are not happy with
the accuracy or efficiency of some of the algorithms that are implemented in pgf. In these cases you will
want to add a function to the parser or replace the current implementations of the algorithms with your own
code.
The mathematical engine was designed with such customization in mind. It is possible to add new
functions, or modify the code for existing functions. Note, however, that whilst adding new operators is
possible, it can be a rather tricky business and is only recommended for adventurous users.
To add a new function to the math engine the following command can be used:
\pgfmathdeclarefunction*{hnamei}{hnumber of argumentsi}{hcodei}
This will set up the parser to recognize a function called hnamei. The name of the function can consist of,
uppercase or lowercase letters, numbers or the underscore _. In line with many programming languages,
a function name cannot begin with a number or contain any spaces. The function may not have been
declared earlier, unless the optional star (*) is provided, which forces an “overwriting” of the function
by the new function. Note that you should never change the arity of standard functions and you should
normally use \pgfmathredeclarefunction, which does not allow you to do anything wrong here.
The hnumber of argumentsi can be any positive integer, zero, or the value ..., which indicates a variable
number of arguments. pgf treats constants, such as pi and e, as functions with zero arguments.
Functions with more than nine arguments or with a variable number of arguments are a “bit special”
and are discussed below.
The effect of hcodei should be to set the macro \pgfmathresult to the correct value (namely to the
result of the computation without units). Furthermore, the function should have no other side effects,
that is, it should not change any global values. As an example, consider the creation of a new function
double, which takes one argument, and returns the value of that argument times two.
88.6
\makeatletter
\pgfmathdeclarefunction{double}{1}{
\begingroup
\pgf@x=#1pt\relax
\multiply\pgf@x by2\relax
\pgfmathreturn\pgf@x
\endgroup
}
\makeatother
\pgfmathparse{double(44.3)}\pgfmathresult
The macro \pgfmathreturnhtokensi must be directly followed by an \endgroup and will save the result
of the computation, by defining \pgfmathresult as the expansion of htokensi (without units) outside
the group, so htokensi must be something that can be assigned to a dimension register.
Alternatively, the \pgfmathsmugglehmacroi can be used. This must also be directly followed by an
\endgroup and will simply “smuggle” the definition of hmacroi outside the TEX-group.
By performing computations within a TEX-group, pgf registers such as \pgf@x, \pgf@y and
\c@pgf@counta, \c@pgfcountb, and so forth, can be used at will.
Beyond setting up the parser, this command also defines two macros which provide access to the function
independently of the parser:
• \pgfmathhfunction namei
This macro will provide a “public” interface for the function hfunction namei allowing the function
to be called independently of the parser. All arguments passed to this macro are evaluated using
\pgfmathparse and then passed on to the following macro:
• \pgfmathhfunction namei@
This macro is the “private” implementation of the function’s algorithm (but note that, for speed,
the parser calls this macro rather than the “public” one). Arguments passed to this macro are
expected to be numbers without units. It is defined using hcodei, but need not be self-contained.
For functions that are declared with less than ten arguments, the public macro is defined in the same
way as normal TEX macros using, for example, \def\pgfmathNoArgs{hcodei} for a function with no arguments, or \def\pgfmathThreeArgs#1#2#3{hcodei} for a function with three arguments. The private
942
macro is defined in the same way, and each argument can therefore be accessed in hcodei using #1, #2
and so on.
For functions with more than nine arguments, or functions with a variable number of arguments, these
macros are only defined as taking one argument. The public macro expects its arguments to be comma
separated, for example, \pgfmathVariableArgs{1.1,3.5,-1.5,2.6}. Each argument is parsed and
passed on to the private macro as follows: \pgfmathVariableArgs@{{1.1}{3.5}{-1.5}{2.6}}. This
means that some “extra work” will be required to access each argument (although it is a fairly simple
task).
Note that there are two exceptions to this arrangement: the public versions of the min and max functions
still take two arguments for compatibility with older versions, but each of these arguments can take
several comma separated values.
To redefine a function use the following command:
\pgfmathredeclarefunction{hfunction namei}{halgorithm codei}
This command redefines the \pgfmathhfunction namei@ macro with the new halgorithm codei. See the
description of the \pgfmathdeclarefunction for details. You cannot change the number of arguments
for an existing function.
84.0 126.0
\makeatletter
\pgfmathdeclarefunction{foo}{1}{
\begingroup
\pgf@x=#1pt\relax
\multiply\pgf@x by2\relax
\pgfmathreturn\pgf@x
\endgroup
}
\pgfmathparse{foo(42)}\pgfmathresult
\pgfmathredeclarefunction{foo}{
\begingroup
\pgf@x=#1pt\relax
\multiply\pgf@x by3\relax
\pgfmathreturn\pgf@x
\endgroup
}
\pgfmathparse{foo(42)}\pgfmathresult
\makeatother
pgf uses the last known definition of a function within the prevailing scope, so it is possible for a
function to be redefined locally. You should also remember that any .sty or .tex file containing any
re-implementations should be loaded after pgfmath.
In addition to the above commands, the following key is provided to quickly create simple ad hoc functions
which can greatly improve the readability of code, and is particularly useful in Tik Z:
/pgf/declare function=hfunction definitionsi
(no default)
This key allows simple functions to be created locally. Its use is perhaps best illustrated by an example:
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\draw [blue, thick, x=0.0085cm, y=1cm,
declare function={
sines(\t,\a,\b)=1 + 0.5*(sin(\t)+sin(\t*\a)+sin(\t*\b));
}]
plot [domain=0:360, samples=144, smooth] (\x,{sines(\x,3,5)});
\end{tikzpicture}
Each definition in hfunction definitionsi takes the form hnamei(hargumentsi)=hdefinitioni; (note the
semicolon at the end, this is very important). If multiple functions are being defined, the semicolon is
used to separate them (not a comma). The function hnamei can be any name that is not already a
function name in the current scope. The list of hargumentsi are commands such as \x, or \y (it is not
possible to declare functions that take variable numbers of arguments using this key). If the function
takes no arguments, then the parentheses need not be used. The hdefinitioni should be an expression
that can be parsed by the mathematical engine and should use the commands specified in hargumentsi.
943
When specifying multiple functions, functions that appear later on in hfunction definitionsi can refer to
earlier functions:
\begin{tikzpicture}[
declare function={
excitation(\t,\w) = sin(\t*\w);
noise
= rnd - 0.5;
source(\t)
= excitation(\t,20) + noise;
filter(\t)
= 1 - abs(sin(mod(\t, 90)));
speech(\t)
= 1 + source(\t)*filter(\t);
}
]
\draw [help lines] (0,0) grid (3,2);
\draw [blue, thick, x=0.0085cm, y=1cm] (0,1) -plot [domain=0:360, samples=144, smooth] (\x,{speech(\x)});
\end{tikzpicture}
944
92
Number Printing
An extension by Christian Feuersänger
pgf supports number printing in different styles and rounds to arbitrary precision.
\pgfmathprintnumber{hx i}
Generates pretty-printed output for the (real) number hx i. The input number hx i is parsed using
\pgfmathfloatparsenumber which allows arbitrary precision.
Numbers are typeset in math mode using the current set of number printing options, see below. Optional
arguments can also be provided using \pgfmathprintnumber[hoptionsi]hx i.
\pgfmathprintnumberto{hx i}{hmacroi}
Returns the resulting number into hmacroi instead of typesetting it directly.
(no value)
/pgf/number format/fixed
Configures \pgfmathprintnumber to round the number to a fixed number of digits after the period,
discarding any trailing zeros.
4.57 0
0.1 24,415.98 123,456.12
\pgfkeys{/pgf/number format/.cd,fixed,precision=2}
\pgfmathprintnumber{4.568}\hspace{1em}
\pgfmathprintnumber{5e-04}\hspace{1em}
\pgfmathprintnumber{0.1}\hspace{1em}
\pgfmathprintnumber{24415.98123}\hspace{1em}
\pgfmathprintnumber{123456.12345}
See section 92.1 for how to change the appearance.
/pgf/number format/fixed zerofill={hbooleani}
(default true)
Enables or disables zero filling for any number drawn in fixed point format.
4.57 0.00 0.10 24,415.98 123,456.12
\pgfkeys{/pgf/number format/.cd,fixed,fixed zerofill,precision=2}
\pgfmathprintnumber{4.568}\hspace{1em}
\pgfmathprintnumber{5e-04}\hspace{1em}
\pgfmathprintnumber{0.1}\hspace{1em}
\pgfmathprintnumber{24415.98123}\hspace{1em}
\pgfmathprintnumber{123456.12345}
This key affects numbers drawn with fixed or std styles (the latter only if no scientific format is
chosen).
4.57 5 · 10−5
1.00 1.23 · 105
\pgfkeys{/pgf/number format/.cd,std,fixed zerofill,precision=2}
\pgfmathprintnumber{4.568}\hspace{1em}
\pgfmathprintnumber{5e-05}\hspace{1em}
\pgfmathprintnumber{1}\hspace{1em}
\pgfmathprintnumber{123456.12345}
See section 92.1 for how to change the appearance.
(no value)
/pgf/number format/sci
Configures \pgfmathprintnumber to display numbers in scientific format, that means sign, mantissa
and exponent (basis 10). The mantissa is rounded to the desired precision (or sci precision, see
below).
4.57 · 100
5 · 10−4
1 · 10−1
2.44 · 104
1.23 · 105
\pgfkeys{/pgf/number format/.cd,sci,precision=2}
\pgfmathprintnumber{4.568}\hspace{1em}
\pgfmathprintnumber{5e-04}\hspace{1em}
\pgfmathprintnumber{0.1}\hspace{1em}
\pgfmathprintnumber{24415.98123}\hspace{1em}
\pgfmathprintnumber{123456.12345}
945
See section 92.1 for how to change the exponential display style.
(default true)
/pgf/number format/sci zerofill={hbooleani}
Enables or disables zero filling for any number drawn in scientific format.
5.00 · 10−4
4.57 · 100
1.00 · 10−1
2.44 · 104
1.23 · 105
\pgfkeys{/pgf/number format/.cd,sci,sci zerofill,precision=2}
\pgfmathprintnumber{4.568}\hspace{1em}
\pgfmathprintnumber{5e-04}\hspace{1em}
\pgfmathprintnumber{0.1}\hspace{1em}
\pgfmathprintnumber{24415.98123}\hspace{1em}
\pgfmathprintnumber{123456.12345}
As with fixed zerofill, this option does only affect numbers drawn in sci format (or std if the
scientific format is chosen).
See section 92.1 for how to change the exponential display style.
(style, default true)
/pgf/number format/zerofill={hbooleani}
Sets both fixed zerofill and sci zerofill at once.
(no value)
(no default)
(no default)
/pgf/number format/std
/pgf/number format/std=hlower ei
/pgf/number format/std=hlower ei:hupper ei
Configures \pgfmathprintnumber to a standard algorithm. It chooses either fixed or sci, depending
on the order of magnitude. Let n = s · m · 10e be the input number and p the current precision. If
−p/2 ≤ e ≤ 4, the number is displayed using fixed format. Otherwise, it is displayed using sci format.
4.57 5 · 10−4
0.1 24,415.98 1.23 · 105
\pgfkeys{/pgf/number format/.cd,std,precision=2}
\pgfmathprintnumber{4.568}\hspace{1em}
\pgfmathprintnumber{5e-04}\hspace{1em}
\pgfmathprintnumber{0.1}\hspace{1em}
\pgfmathprintnumber{24415.98123}\hspace{1em}
\pgfmathprintnumber{123456.12345}
The parameters can be customized using the optional integer argument(s): if hlower ei ≤ e ≤ hupper ei,
the number is displayed in fixed format, otherwise in sci format. Note that hlower ei should be negative
for useful results. The precision used for the scientific format can be adjusted with sci precision if
necessary.
/pgf/number format/relative*=hexponent base 10 i
(no default)
r
Configures \pgfmathprintnumber to format numbers relative to an order of magnitude, 10 , where r is
an integer number.
This key addresses different use-cases.
First use-case: provide a unified format for a sequence of numbers. Consider the following test:
0 1.2 6
20.6 87
\pgfkeys{/pgf/number format/relative*={1}}
\pgfmathprintnumber{6.42e-16}\hspace{1em}
\pgfmathprintnumber{1.2}\hspace{1em}
\pgfmathprintnumber{6}\hspace{1em}
\pgfmathprintnumber{20.6}\hspace{1em}
\pgfmathprintnumber{87}
With any other style, the 6.42e-16 would have been formatted as an isolated number. Here, it is
rounded to 0 because when viewed relative to 101 (the exponent 1 is the argument for relative), it
has no significant digits.
123 0
0
\pgfkeys{/pgf/number format/relative*={2}}
\pgfmathprintnumber{123.345}\hspace{1em}
\pgfmathprintnumber{0.0012}\hspace{1em}
\pgfmathprintnumber{0.0014}\hspace{1em}
946
The example above applies the initial precision=2 to 123.345 – relative to 100. Two significant digits
of 123.345 relative to 100 are 123. Note that the “2 significant digits of 123.345” translates to “round
1.2345 to 2 digits”, which would yield 1.2300. Similarly, the other two numbers are 0 compared to 100
using the given precision.
123.345 1.2 · 10−3
1.4 · 10−3
\pgfkeys{/pgf/number format/relative*={-3}}
\pgfmathprintnumber{123.345}\hspace{1em}
\pgfmathprintnumber{0.0012}\hspace{1em}
\pgfmathprintnumber{0.0014}\hspace{1em}
Second use-case: improve rounding in the presence of inaccurate numbers. Let us suppose that
some limited-precision arithmetics resulted in the result 123456999 (like the fpu of pgf). You know
that its precision is about five or six significant digits. And you want to provide a fixed point output.
In this case, the trailing digits ....999 are a numerical artifact due to the limited precision. Use
relative*=3,precision=0 to eliminate the artifacts:
1.23457 · 108
1.23457 · 108
\pgfkeys{/pgf/number format/.cd,relative*={3},precision=0}
\pgfmathprintnumber{123456999}\hspace{1em}
\pgfmathprintnumber{123456999.12}
Here, precision=0 means that we inspect 123456.999 and round that number to 0 digits. Finally,
we move the period back to its initial position. Adding relative style=fixed results in fixed point
output format:
123,457,000 123,457,000
\pgfkeys{/pgf/number format/.cd,relative*={3},precision=0,relative style=fixed}
\pgfmathprintnumber{123456999}\hspace{1em}
\pgfmathprintnumber{123456999.12}
Note that there is another alternative for this use-case which is discussed later: the fixed relative
style.
123,457,000 123,457,000
\pgfkeys{/pgf/number format/.cd,fixed relative,precision=6}
\pgfmathprintnumber{123456999}\hspace{1em}
\pgfmathprintnumber{123456999.12}
You might wonder why there is an asterisk in the key’s name. The short answer is: there is also a
/pgf/number
format/relative number printer which does unexpected things. The key relative*
repairs this. Existing code will still use the old behavior.
Technically, the key works as follows: as already explained above, relative*=3 key applied to
123456999.12 moves the period by three positions and analyzes 123456.99912. Mathematically speaking, we are given a number x = ±m · 10e and we attempt to apply relative*=r. The method then
rounds x/10r to precision digits. Afterwards, it multiplies the result by 10r and typesets it.
(style, no value)
/pgf/number format/every relative
A style which configures how the relative method finally displays its results.
The initial configuration is
\pgfkeys{/pgf/number format/every relative/.style=std}
Note that rounding is turned off when the resulting style is being evaluated (since relative already
rounded the number).
Although supported, I discourage from using fixed zerofill or sci zerofill in this context – it may
lead to a suggestion of higher precision than is actually used (because fixed zerofill might simply
add .00 although there was a different information before relative rounded the result).
/pgf/number format/relative style={hoptionsi}
The same as every relative/.append style={hoptionsi}.
947
(no default)
(no value)
/pgf/number format/fixed relative
Configures \pgfmathprintnumber to format numbers in a similar way to the fixed style, but the
precision is interpreted relatively to the number’s exponent.
The motivation is to get the same rounding effect as for sci, but to display the number in the fixed
style:
1,000 100
0.00001 0.0101 1.24 1,000 1,010
\pgfkeys{/pgf/number format/.cd,fixed relative,precision=3}
\pgfmathprintnumber{1000.0123}\hspace{1em}
\pgfmathprintnumber{100.0567}\hspace{1em}
\pgfmathprintnumber{0.000010003452}\hspace{1em}
\pgfmathprintnumber{0.010073452}\hspace{1em}
\pgfmathprintnumber{1.23567}\hspace{1em}
\pgfmathprintnumber{1003.75}\hspace{1em}
\pgfmathprintnumber{1006.75}\hspace{1em}
The effect of fixed relative is that the number is rounded to exactly the first hprecisioni non-zero
digits, no matter how many leading zeros the number might have.
Use fixed relative if you want fixed and if you know that only the first n digits are correct. Use
sci if you need a scientific display style and only the first n digits are correct.
Note that fixed relative ignores the fixed zerofill flag.
See also the relative* key. Note that the relative={hexponenti} key explicitly moves the period to
some designated position before it attempts to round the number. Afterwards, it “rounds from the right”,
i.e. it rounds to that explicitly chosen digit position. In contrast to that, fixed relative “rounds from
the left”: it takes the first non-zero digit, temporarily places the period after this digit, and rounds that
number. The rounding style fixed leaves the period where it is, and rounds everything behind that
digit. The sci style is similar to fixed relative.
(no value)
/pgf/number format/int detect
Configures \pgfmathprintnumber to detect integers automatically. If the input number is an integer,
no period is displayed at all. If not, the scientific format is chosen.
2.04 · 101
15 20
1 · 10−2
0
\pgfkeys{/pgf/number format/.cd,int detect,precision=2}
\pgfmathprintnumber{15}\hspace{1em}
\pgfmathprintnumber{20}\hspace{1em}
\pgfmathprintnumber{20.4}\hspace{1em}
\pgfmathprintnumber{0.01}\hspace{1em}
\pgfmathprintnumber{0}
\pgfmathifisint{hnumber constanti}{htrue codei}{hfalse codei}
A command which does the same check as int detect, but it invokes htrue codei if the hnumber
constanti actually is an integer and the hfalse codei if not.
As a side-effect, \pgfretval will contain the parsed number, either in integer format or as parsed
floating point number.
The argument hnumber constanti will be parsed with \pgfmathfloatparsenumber.
15 is an int: 15.
15.5 is no int
15 \pgfmathifisint{15}{is an int: \pgfretval.}{is no int}\hspace{1em}
15.5 \pgfmathifisint{15.5}{is an int: \pgfretval.}{is no int}
(no value)
/pgf/number format/int trunc
Truncates every number to integers (discards any digit after the period).
4 0
0
24,415 123,456
948
\pgfkeys{/pgf/number format/.cd,int trunc}
\pgfmathprintnumber{4.568}\hspace{1em}
\pgfmathprintnumber{5e-04}\hspace{1em}
\pgfmathprintnumber{0.1}\hspace{1em}
\pgfmathprintnumber{24415.98123}\hspace{1em}
\pgfmathprintnumber{123456.12345}
(no value)
/pgf/number format/frac
Displays numbers as fractionals.
1
3
1
2
16
75
3
25
2
75
1
− 75
18
25
1
15
2
15
1
− 75
3 13
1 22657
96620
1 −6
\pgfkeys{/pgf/number format/frac}
\pgfmathprintnumber{0.333333333333333}\hspace{1em}
\pgfmathprintnumber{0.5}\hspace{1em}
\pgfmathprintnumber{2.133333333333325e-01}\hspace{1em}
\pgfmathprintnumber{0.12}\hspace{1em}
\pgfmathprintnumber{2.666666666666646e-02}\hspace{1em}
\pgfmathprintnumber{-1.333333333333334e-02}\hspace{1em}
\pgfmathprintnumber{7.200000000000000e-01}\hspace{1em}
\pgfmathprintnumber{6.666666666666667e-02}\hspace{1em}
\pgfmathprintnumber{1.333333333333333e-01}\hspace{1em}
\pgfmathprintnumber{-1.333333333333333e-02}\hspace{1em}
\pgfmathprintnumber{3.3333333}\hspace{1em}
\pgfmathprintnumber{1.2345}\hspace{1em}
\pgfmathprintnumber{1}\hspace{1em}
\pgfmathprintnumber{-6}
(no default, initially \frac)
/pgf/number format/frac TeX={h\macroi}
Allows to use a different implementation for \frac inside of the frac display type.
(no default, initially empty)
/pgf/number format/frac denom=hinti
Allows to provide a custom denominator for frac.
1
10
5
10
2
1 10
6
− 10
4
−1 10
\pgfkeys{/pgf/number format/.cd,frac, frac denom=10}
\pgfmathprintnumber{0.1}\hspace{1em}
\pgfmathprintnumber{0.5}\hspace{1em}
\pgfmathprintnumber{1.2}\hspace{1em}
\pgfmathprintnumber{-0.6}\hspace{1em}
\pgfmathprintnumber{-1.4}\hspace{1em}
/pgf/number format/frac whole=true|false
(no default, initially true)
Configures whether complete integer parts shall be placed in front of the fractional part. In this case,
the fractional part will be less then 1. Use frac whole=false to avoid whole number parts.
201
10
11
2
6
5
− 28
5
− 75
\pgfkeys{/pgf/number format/.cd,frac, frac whole=false}
\pgfmathprintnumber{20.1}\hspace{1em}
\pgfmathprintnumber{5.5}\hspace{1em}
\pgfmathprintnumber{1.2}\hspace{1em}
\pgfmathprintnumber{-5.6}\hspace{1em}
\pgfmathprintnumber{-1.4}\hspace{1em}
/pgf/number format/frac shift={hinteger i}
(no default, initially 4)
In case you experience problems because of stability problems, try experimenting with a different frac shift. Higher shift values k yield higher sensitivity to inaccurate data or inaccurate
arithmetics.
Technically, the following happens. If r < 1 is the fractional part of the mantissa, then a scale
i = 1/r · 10k is computed where k is the shift; fractional parts of i are neglected. The value 1/r is
computed internally, its error is amplified.
949
If you still experience stability problems, use \usepackage{fp} in your preamble. The frac style
will then automatically employ the higher absolute precision of fp for the computation of 1/r.
/pgf/number format/precision={hnumber i}
(no default)
Sets the desired rounding precision for any display operation. For scientific format, this affects the
mantissa.
/pgf/number format/sci precision=hnumber or emptyi
(no default, initially empty)
Sets the desired rounding precision only for sci styles.
Use sci precision={} to restore the initial configuration (which uses the argument provided to
precision for all number styles).
/pgf/number format/read comma as period=true|false
(no default, initially false)
This is one of the few keys which allows to customize the number parser. If this switch is turned on, a
comma is read just as a period.
1,234.56
\pgfkeys{/pgf/number format/read comma as period}
\pgfmathprintnumber{1234,56}
This is typically undesired as it can cause side–effects with math parsing instructions. However, it is
supported to format input numbers or input tables. Consider use comma to typeset the result with a
comma as well.
1.234,56
92.1
\pgfkeys{/pgf/number format/.cd,
read comma as period,
use comma}
\pgfmathprintnumber{1234,56}
Changing display styles
You can change the way how numbers are displayed. For example, if you use the ‘fixed’ style, the input
number is rounded to the desired precision and the current fixed point display style is used to typeset the
number. The same is applied to any other format: first, rounding routines are used to get the correct digits,
afterwards a display style generates proper TEX-code.
/pgf/number format/set decimal separator={htexti}
(no default)
Assigns {htexti} as decimal separator for any fixed point numbers (including the mantissa in sci format).
Use \pgfkeysgetvalue{/pgf/number format/set decimal separator}\value to get the current
separator into \value.
(style, no default)
/pgf/number format/dec sep={htexti}
Just another name for set decimal separator.
/pgf/number format/set thousands separator={htexti}
(no default)
Assigns {htexti} as thousands separator for any fixed point numbers (including the mantissa in sci
format).
1234.56
\pgfkeys{/pgf/number format/.cd,
fixed,
fixed zerofill,
precision=2,
set thousands separator={}}
\pgfmathprintnumber{1234.56}
1234567890.00
\pgfkeys{/pgf/number format/.cd,
fixed,
fixed zerofill,
precision=2,
set thousands separator={}}
\pgfmathprintnumber{1234567890}
950
1.234.567.890.00
\pgfkeys{/pgf/number format/.cd,
fixed,
fixed zerofill,
precision=2,
set thousands separator={.}}
\pgfmathprintnumber{1234567890}
1, 234, 567, 890.00
\pgfkeys{/pgf/number format/.cd,
fixed,
fixed zerofill,
precision=2,
set thousands separator={,}}
\pgfmathprintnumber{1234567890}
1,234,567,890.00
\pgfkeys{/pgf/number format/.cd,
fixed,
fixed zerofill,
precision=2,
set thousands separator={{{,}}}}
\pgfmathprintnumber{1234567890}
The last example employs commas and disables the default comma-spacing.
Use \pgfkeysgetvalue{/pgf/number format/set thousands separator}\value to get the current
separator into \value.
(style, no default)
/pgf/number format/1000 sep={htexti}
Just another name for set thousands separator.
/pgf/number format/1000 sep in fractionals={hbooleani}
(no default, initially false)
Configures whether the fractional part should also be grouped into groups of three digits.
The value true will active the 1000 sep for both, integer and fractional parts. The value false will
active 1000 sep only for the integer part.
1 234.123 456 7
\pgfkeys{/pgf/number format/.cd,
fixed,
precision=999,
set thousands separator={\,},
1000 sep in fractionals,
}
\pgfmathprintnumber{1234.1234567}
1 234.123 456 700
\pgfkeys{/pgf/number format/.cd,
fixed,fixed zerofill,
precision=9,
set thousands separator={\,},
1000 sep in fractionals,
}
\pgfmathprintnumber{1234.1234567}
/pgf/number format/min exponent for 1000 sep={hnumber i}
(no default, initially 0)
Defines the smallest exponent in scientific notation which is required to draw thousand separators. The
exponent is the number of digits minus one, so hnumber i = 4 will use thousand separators starting with
1e4 = 10000.
5 000; 1 000 000
1000; 5000
\pgfkeys{/pgf/number format/.cd,
int detect,
1000 sep={\,},
min exponent for 1000 sep=0}
\pgfmathprintnumber{5000}; \pgfmathprintnumber{1000000}
\pgfkeys{/pgf/number format/.cd,
int detect,
1000 sep={\,},
min exponent for 1000 sep=4}
\pgfmathprintnumber{1000}; \pgfmathprintnumber{5000}
951
10 000; 1 000 000
\pgfkeys{/pgf/number format/.cd,
int detect,
1000 sep={\,},
min exponent for 1000 sep=4}
\pgfmathprintnumber{10000}; \pgfmathprintnumber{1000000}
A value of 0 disables this feature (negative values are ignored).
(no value)
/pgf/number format/use period
A predefined style which installs periods “.” as decimal separators and commas “,” as thousands
separators. This style is the default.
12.35
\pgfkeys{/pgf/number format/.cd,fixed,precision=2,use period}
\pgfmathprintnumber{12.3456}
1,234.56
\pgfkeys{/pgf/number format/.cd,fixed,precision=2,use period}
\pgfmathprintnumber{1234.56}
(no value)
/pgf/number format/use comma
A predefined style which installs commas “,” as decimal separators and periods “.” as thousands
separators.
12,35
\pgfkeys{/pgf/number format/.cd,fixed,precision=2,use comma}
\pgfmathprintnumber{12.3456}
1.234,56
\pgfkeys{/pgf/number format/.cd,fixed,precision=2,use comma}
\pgfmathprintnumber{1234.56}
(no default, initially false)
/pgf/number format/skip 0.={hbooleani}
Configures whether numbers like 0.1 shall be typeset as .1 or not.
.56
\pgfkeys{/pgf/number format/.cd,
fixed,
fixed zerofill,precision=2,
skip 0.}
\pgfmathprintnumber{0.56}
0.56
\pgfkeys{/pgf/number format/.cd,
fixed,
fixed zerofill,precision=2,
skip 0.=false}
\pgfmathprintnumber{0.56}
(no default, initially false)
/pgf/number format/showpos={hbooleani}
Enables or disables the display of plus signs for non-negative numbers.
+12.35
12.35
+1.23 · 101
\pgfkeys{/pgf/number format/showpos}
\pgfmathprintnumber{12.345}
\pgfkeys{/pgf/number format/showpos=false}
\pgfmathprintnumber{12.345}
\pgfkeys{/pgf/number format/.cd,showpos,sci}
\pgfmathprintnumber{12.345}
(style, no default)
/pgf/number format/print sign={hbooleani}
A style which is simply an alias for showpos={hbooleani}.
952
(no value)
/pgf/number format/sci 10e
Uses m · 10e for any number displayed in scientific format.
1.23 · 101
\pgfkeys{/pgf/number format/.cd,sci,sci 10e}
\pgfmathprintnumber{12.345}
(no value)
/pgf/number format/sci 10^e
The same as ‘sci 10e’.
(no value)
/pgf/number format/sci e
Uses the ‘1e+0’ format which is generated by common scientific tools for any number displayed in
scientific format.
1.23e+1
\pgfkeys{/pgf/number format/.cd,sci,sci e}
\pgfmathprintnumber{12.345}
(no value)
/pgf/number format/sci E
The same with an uppercase ‘E’.
1.23E+1
\pgfkeys{/pgf/number format/.cd,sci,sci E}
\pgfmathprintnumber{12.345}
(no value)
/pgf/number format/sci subscript
Typesets the exponent as subscript for any number displayed in scientific format. This style requires
very little space.
1.231
\pgfkeys{/pgf/number format/.cd,sci,sci subscript}
\pgfmathprintnumber{12.345}
(no value)
/pgf/number format/sci superscript
Typesets the exponent as superscript for any number displayed in scientific format. This style requires
very little space.
1.231
\pgfkeys{/pgf/number format/.cd,sci,sci superscript}
\pgfmathprintnumber{12.345}
(no default)
/pgf/number format/sci generic={hkeysi}
Allows to define an own number style for the scientific format. Here, hkeysi can be one of the following
choices (omit the long key prefix):
/pgf/number format/sci generic/mantissa sep={htexti}
(no default, initially empty)
Provides the separator between a mantissa and the exponent. It might be \cdot, for example,
/pgf/number format/sci generic/exponent={htexti}
(no default, initially empty)
Provides text to format the exponent. The actual exponent is available as argument #1 (see below).
1.23 × 101 ;1.23 × 10−4
\pgfkeys{
/pgf/number format/.cd,
sci,
sci generic={mantissa sep=\times,exponent={10^{#1}}}}
\pgfmathprintnumber{12.345};
\pgfmathprintnumber{0.00012345}
The hkeysi can depend on three parameters, namely on #1 which is the exponent, #2 containing the
flags entity of the floating point number and #3 is the (unprocessed and unformatted) mantissa.
Note that sci generic is not suitable to modify the appearance of fixed point numbers, nor can it be
used to format the mantissa (which is typeset like fixed point numbers). Use dec sep, 1000 sep and
print sign to customize the mantissa.
953
(no default)
/pgf/number format/@dec sep mark={htexti}
Will be placed right before the place where a decimal separator belongs to. However, {htexti} will be
inserted even if there is no decimal separator. It is intended as place-holder for auxiliary routines to
find alignment positions.
This key should never be used to change the decimal separator! Use dec sep instead.
/pgf/number format/@sci exponent mark={htexti}
(no default)
Will be placed right before exponents in scientific notation. It is intended as place-holder for auxiliary
routines to find alignment positions.
This key should never be used to change the exponent!
/pgf/number format/assume math mode={hbooleani}
(default true)
Set this to true if you don’t want any checks for math mode. The initial setting checks whether math
mode is active using \pgfutilensuremath for each final number.
Use assume math mode=true if you know that math mode is active. In that case, the final number is
typeset as-is, no further checking is performed.
(style, no value)
/pgf/number format/verbatim
A style which configures the number printer to produce verbatim text output, i. e., it doesn’t contain
TEX macros.
1.23e1;1.23e-4;3.27e6
\pgfkeys{
/pgf/fpu,
/pgf/number format/.cd,
sci,
verbatim}
\pgfmathprintnumber{12.345};
\pgfmathprintnumber{0.00012345};
\pgfmathparse{exp(15)}
\pgfmathprintnumber{\pgfmathresult}
The style resets 1000 sep, dec sep, print sign, skip 0. and sets assume math mode. Furthermore,
it installs a sci generic format for verbatim output of scientific numbers.
However, it will still respect precision, fixed zerofill, sci zerofill and the overall styles fixed,
sci, int detect (and their variants). It might be useful if you intend to write output files.
954
93
Object-Oriented Programming
This section describes the oo module.
\usepgfmodule{oo} % LATEX and plain TEX and pure pgf
\usepgfmodule[oo] % ConTEXt and pure pgf
This module defines a relatively small set of TEX commands for defining classes, methods, attributes
and objects in the sense of object-oriented programming.
In this chapter it is assumed that you are familiar with the basics of a typical object-oriented programming
language like Java, C++ or Eiffel.
93.1
Overview
TEX does not support object-oriented programming, presumably because it was written at a time when this
style of programming was not yet “en vogue.” When one is used to the object-oriented style of thinking, some
programming constructs in TEX often seem overly complicated. The object-oriented programming module
of pgf may help here. It is written completely using simple TEX macros and is, thus, perfectly portable.
This also means, however, that it is not particularly fast (but not too slow either), so you should use it only
for non-time-critical things.
Basically, the oo-system supports classes (in the object-oriented sense, this has nothing to do with
LATEX-classes), methods, constructors, attributes, objects, object identities, and (thanks to Saǒ Živanović)
inheritance and overloading.
The first step is to define a class, using the macro \pgfooclass (all normal macros in pgf’s object-oriented
system start with \pgfoo). This macro gets the name of a class and in its body a number of methods are
defined. These are defined using the \method macro (which is defined only inside such a class definition) and
they look a bit like method definitions in, say, Java. Object attributes are declared using the \attribute
command, which is also defined only inside a class definition.
Once a class has been defined, you can create objects of this class. Objects are created using \pgfoonew.
Such an object has many characteristics of objects in a normal object-oriented programming language: Each
object has a unique identity, so when you create another object, this object is completely distinct from all
other objects. Each object also has a set of private attributes, which may change over time. Suppose, for
instance, that we have a point class. Then creating a new object (called an instance) of this class would
typically have an x-attribute and a y-attribute. These can be changed over time. Creating another instance
of the point class creates another object with its own x- and y-attributes.
Given an object, you can call a method for this object. Inside the method the attributes of the object
for which the method is being called can be accessed.
The life of an object always ends with the end of the TEX scope in which it was created. However,
changes to attribute values are not local to scopes, so when you change an attribute anywhere, this change
persists till the end of the life of the object or until the attribute is changed again.
93.2
A Running Example: The Stamp Class
As a running example we will develop a stamp class and stamp objects. The idea is that a stamp object is
able to “stamp something” on a picture. This means that a stamp object has an attribute storing the “stamp
text” and there is a method that asks the object to place this text somewhere on a canvas. The method
can be called repeatedly and there can be several different stamp objects, each producing a different text.
Stamp objects can either be created dynamically when needed or a library might define many such objects
in an outer scope.
Such stamps are similar to many things present in pgf such as arrow tips, patterns, or shadings and,
indeed, these could all have been implemented in this object-oriented fashion (which might have been better,
but the object-oriented subsystem is a fairly new addition to pgf).
93.3
Classes
We start with the definition of the stamp class. This is done using the \pgfooclass macro:
\pgfooclass(hlist of superclassesi){hclass namei}{hbodyi}
955
This command defines a class named hclass namei. The name of the class can contain spaces and most
other characters, but no periods. So, valid class names are MyClass or my class or Class_C++_emulation??1. The hlist of superclassesi is optional just like the parenthesis around it.
The hbodyi is actually just executed, so any normal TEX-code is permissible here. However, while the
hbodyi is being executed, the macros \method and \attribute are set up so that they can be used to
define methods and attributes for this class (the original meanings are restored afterward).
The definition of a class is local to the scope where the class has been defined.
\pgfooclass{stamp}{
% This is the class stamp
\attribute text;
\attribute rotation angle=20;
\method stamp(#1) { % The constructor
...
}
\method apply(#1,#2) { % Causes the stamp to be shown at coordinate (#1,#2)
...
}
}
% We can now create objects of type "stamp"
Concerning the list of base classes, the Method Resolution Order (mro) is computed using the C3
algorithm also used in Python, v2.3 and higher. The linearization computed by the algorithm respects
both local precedence ordering and monotonicity. Resolution of both methods and attributes depends
on the mro: when a method method name is called on an object of class C, the system invokes method
method name from the first class in the mro of C which defines method method name; when an object
is created, each attribute attr is initialized to the value specified in the first class in the mro of C
which declares attribute attr.
The hbodyi of a class usually just consists of calls to the macros \attribute and \method, which will be
discussed in more detail in later sections.
93.4
Objects
Once a class has been declared, we can start creating objects for this class. For this the \pgfoonew command
can be used, which has a peculiar syntax:
\pgfoonewhobject handle or attributei=newhclass namei(hconstructor argumentsi)
Causes a new object to be created. The class of the object will be hclass namei, which must previously
have been declared using \pgfooclass. Once the object has been created, the constructor method of
the object will be called with the parameter list set to hconstructor argumentsi.
The resulting object is stored internally and its lifetime will end exactly at the end of the current scope.
Here is an example in which three stamp objects are created.
\pgfoonew \firststamp = new stamp()
\pgfoonew \secondstamp = new stamp()
{
\pgfoonew \thirdstamp = new stamp()
...
}
% \thirdstamp no longer exists, but \firststamp and \secondstamp do
% even if you try to store \thirdstamp in a global variable, trying
% to access it will result in an error.
The optional hobject handle or attributei can either be an hobject handlei or an hattributei. When an
hobject handlei is given, it must be a normal TEX macro name that will “point” to the object (handles
are discussed in more detail in Section 93.7). You can use this macro to call methods of the object as
discussed in the following section. When an hattributei is given, it must be given in curly braces (the
curly braces are used to detect the presence of an attribute). In this case, a handle to the newly created
object is stored in this attribute.
956
\pgfooclass{foo}
{
\attribute stamp obj;
\attribute another object;
\method \foo() {
\pgfoonew{stamp obj}=new stamp()
\pgfoonew{another object}=new bar()
}
...
}
\pgfoogc
This command causes the “garbage collector” to be invoked. The job of this garbage collector is to free
the global TEX-macros that are used by “dead” objects (objects whose life-time has ended). This macro
is called automatically after every scope in which an object has been created, so you normally do not
need to call this macro yourself.
93.5
Methods
Methods are defined inside the body of classes using the following command:
\methodhmethod namei(hparameter listi){hmethod bodyi}
This macro, which is only defined inside a class definition, defines a new method named hmethod namei.
Just like class names, method names can contain spaces and other characters, so hmethod namesi like
put_stamp_here or put stamp here are both legal.
Three method names are special: First, a method having either the same name as the class or having the
name init is called the constructor of the class. There are (currently) no destructors; objects simply
become “undefined” at the end of the scope in which they have been created. The other two methods are
called get id and get handle, which are always automatically defined and which you cannot redefine.
They are discussed in Section 93.7.
Overloading of methods by differing numbers of parameters is not possible, that is, it is illegal to have two
methods inside a single class with the same name (despite possibly different parameter lists). However,
two different classes may contain a method with the same name, that is, classes form namespaces for
methods. Also, a class can (re)implement a method from a superclass.
The hmethod namei must be followed by a hparameter listi in parentheses, which must be present
even when the hparameter listi is empty. The hparameter listi is actually a normal TEX parameter list
that will be matched against the parameters inside the parentheses upon method invocation and, thus,
could be something like #1#2 foo #3 bar., but a list like #1,#2,#3 is more customary. By setting the
parameter list to just #1 and then calling, say, \pgfkeys{#1} at the beginning of a method, you can
implement Objective-C-like named parameters.
When a method is called, the hbodyi of the method will be executed. The main difference to a normal
macro is that while the hbodyi is executed, a special macro called \pgfoothis is set up in such a way
that it references the object for which the method is executed.
In order to call a method for an object, you first need to create the object and you need a handle for this
object. In order to invoke a method for this object, a special syntax is used that is similar to Java or C++
syntax:
hobject handlei.hsuper classi.hmethod namei(hparametersi)
This causes the method hmethod namei to be called for the object referenced by the hobject handlei.
The method is the one defined in the class of the object or, if it is not defined there, the method defined
in the superclasses of the object’s class (if there are several superclasses that define the same method,
the method resolution order is used to determine which one gets called). If the optional hsuper classi
is specified, the method implementation of that class will be used rather than the implementation in
the object’s class. The hparametersi are matched against the parameters of the method and, then, the
method body is executed. The execution of the method body is not done inside a scope, so the effects
of a method body persist.
957
\pgfooclass{stamp}{
% This is the class stamp
\method stamp() { % The constructor
}
\method apply(#1,#2) { % Causes the stamp to be shown at coordinate (#1,#2)
% Draw the stamp:
\node [rotate=20,font=\huge] at (#1,#2) {Passed};
}
}
\pgfoonew \mystamp=new stamp()
\begin{tikzpicture}
\mystamp.apply(1,2)
\mystamp.apply(3,4)
\end{tikzpicture}
Inside a method, you can call other methods. If you have a handle for another object, you can simply
call it in the manner described above. In order to call a method of the current object, you can use the
special object handle \pgfoothis.
\pgfoothis
This object handle is defined only when a method is being executed. There, it is then set to point
to the object for which the method is being called, which allows you to call another method for the
same object.
\pgfooclass{stamp}{
% This is the class stamp
\method stamp() {}
\method apply(#1,#2) {
\pgfoothis.shift origin(#1,#2)
% Draw the stamp:
\node [rotate=20,font=\huge] {Passed};
}
% Private method:
\method shift origin(#1,#2) {
\tikzset{xshift=#1,yshift=#2}
}
}
\pgfoosuper(hclassi,hobject handlei).hmethod namei(hargumentsi)
This macro gives you finer control over which method gets invoked in case of multiple inheritance. This
macro calls hmethod namei of the object specified by hobject handlei, but which implementation of the
method is called is determined as follows: it will be the implementation in the first class (in the method
resolution order) after hclassi that defines hmethod namei.
93.6
Attributes
Every object has a set of attributes, which may change over time. Attributes are declared using the
\attribute command, which, like the \method command, is defined only inside the scope of \pgfooclass.
Attributes can be modified (only) by methods. To take the stamp example, an attribute of a stamp object
might be the text that should be stamped when the apply method is called.
When an attribute is changed, this change is not local to the current TEX group. Changes will persist
till the end of the object’s life or until the attribute is changed once more.
To declare an attribute you should use the \attribute command:
\attributehattribute namei=hinitial valuei;
This command can only be given inside the body of an \pgfooclass command. It declares the attribute
named hattribute namei. This name, like method or class names, can be quite arbitrary, but should not
contain periods. Valid names are an_attribute? or my attribute.
958
You can optionally specify an hinitial valuei for the attribute; if none is given, the empty string is used
automatically. The initial value is the value that the attribute will have just after the object has been
created and before the constructor is called.
\pgfooclass{stamp}{
% This is the class stamp
\attribute text;
\attribute rotation angle = 20;
\method stamp(#1) {
\pgfooset{text}{#1} % Set the text
}
\method apply(#1,#2) {
\pgfoothis.shift origin(#1,#2)
% Draw the stamp:
\node [rotate=\pgfoovalueof{rotation angle},font=\huge]
{\pgfoovalueof{text}};
}
\method shift origin(#1,#2) { ... }
\method set rotation (#1) {
\pgfooset{rotation angle}{#1}
}
}
Attributes can be set and read only inside methods, it is not possible to do so using an object handle.
Spoken in terms of traditional object-oriented programming, attributes are always private. You need to
define getter and setter methods if you wish to read or modify attributes.
Reading and writing attributes is not done using the “dot-notation” that is used for method calls. This
is mostly due to efficiency reasons. Instead, a set of special macros is used, all of which can only be used
inside methods.
\pgfooset{hattributei}{hvaluei}
Sets the hattributei of the current object to hvaluei.
\method set rotation (#1) {
\pgfooset{rotation angle}{#1}
}
\pgfoolet{hattributei}{hmacroi}
Sets the hattributei of the current value to the current value of hmacroi using TEX’s \let command.
\method foo () {
\pgfoolet{my func}\myfunc
% Changing \myfunc now has no effect on the value of attribute my func
}
\pgfoovalueof{hattributei}
Expands (eventually) to the current value of hattributei of the current object.
\method apply(#1,#2) {
\pgfoothis.shift origin(#1,#2)
\node [rotate=\pgfoovalueof{rotation angle},font=\huge]
{\pgfoovalueof{text}};
}
\pgfooget{hattributei}{hmacroi}
Reads the current value of hattributei and stores the result in hmacroi.
959
...
\method get rotation (#1) {
\pgfooget{rotation angle}{#1}
}
...
\mystamp.get rotation(\therotation)
“\therotation” is now “20” (or whatever).
93.7
Identities
Every object has a unique identity, which is simply an integer. It is possible to retrieve the object id using
the get id method (discussed below), but normally you will not need to do so because the id itself cannot
be used to access an object. Rather, you access objects via their methods and these, in turn, can only be
called via object handles.
Object handles can be created in four ways:
1. Calling \pgfoonewhobject handlei=... will cause hobject handlei to be a handle to the newly created
object.
2. Using \let to create an alias of an existing object handle: If \mystamp is a handle, saying
\let\myotherstamp=\mystamp creates a second handle to the same object.
3. \pgfooobj{hid i} can be used as an object handle to the object with the given hid i.
4. Using the get handle method to create a handle to a given object.
Let us have a look at the last two methods.
\pgfooobj{hid i}
Provided that hid i is the id of an existing object (an object whose life-time has not expired), calling
this command yields a handle to this object. The handle can then be used to call methods:
% Create a new object:
\pgfoonew \mystamp=new stamp()
% Get the object’s id and store it in \myid:
\mystamp.get id(\myid)
% The following two calls have the same effect:
\mystamp.apply(1,1)
\pgfooobj{\myid}.apply(1,1)
The get id method can be used to retrieve the id of an object. This method is predefined for every class
and you should not try to define a method of this name yourself.
Method get id(hmacroi)
(predefined for all classes)
Calling hobj i.get id(hmacroi) stores the id hobj i in hmacroi. This is mainly useful when you wish to
store an object for a longer time and you cannot guarantee that any handle that you happen to have
for this object will be available later on.
The only way to use the retrieved id later on is to call \pgfooobj.
Different object that are alive (that are still within the scope in which they were created) will always
have different ids, so you can use the id to test for equality of objects. However, after an object has
been destroyed because its scope has ended, the same id may be used again for newly created objects.
Here is a typical application where you need to call this method: You wish to collect a list of objects
for which you wish to call a specific method from time to time. For the collection process you wish to
offer a macro called \addtoobjectlist, which takes an object handle as parameter. It is quite easy
to store this handle somewhere, but a handle is, well, just a handle. Typically, shortly after the call to
\addtoobjectlist the handle will no longer be valid or even exist, even though the object still exists.
In this case, you wish to store the object id somewhere instead of the handle. Thus, for the object
passed to \addtoobjectlist you call the get id method and store the resulting id, rather than the
handle.
960
There is a second predefined method, called get handle, which is also used to create object handles.
Method get handle({hmacro namei})
(predefined for all classes)
Calling this method for an object will cause hmacro namei to become a handle to the given object. For
any object handle \obj – other than \pgfoothis – the following two have the same effect:
1. \lethmacro namei=\obj
2. \obj.get handle(hmacro namei)
The first method is simpler and faster. However, for \pgfoothis there is a difference: The call
\pgfoothis.get handle(hmacro namei) will cause hmacro namei to be an object handle to the current object and will persist to be so even after the method is done. By comparison, \lethmacro
namei=\pgfoothis causes \obj to be the same as the very special macro \pgfoothis, so \obj will
always refer to the current object, which may change over time.
93.8
The Object Class
The object-oriented module predefines a basic class object that can be used as a base class in different
context.
Class object
This class current only implements one method:
Method copy(hhandlei)
Creates a new object and initializes the values of its (declared) attributes to the values of the
original. The method takes one argument: a control sequence which receives the handle of the
copy.
93.9
The Signal Class
In addition to the basic mechanism for defining and using classes and object, the class signal is predefined.
It implements a so-called signal–slot mechanism.
Class signal
This class is used to implement a simple signal–slot mechanism. The idea is the following: From time to
time special things happen about which a number of objects need to be informed. Different things can
happen and different object will be interested in these things. A signal object can be used to signal
that such special things of a certain kind have happened. For example, one signal object might be used
to signal the event that “a page has been shipped out.” Another signal might be used to signal that “a
figure is about to be typeset,” and so on.
Objects can “tune in” to signals. They do so by connecting one of their methods (then called a slot)
to the signal. Then, whenever the signal is emitted, the method of the connected object(s) get called.
Different objects can connect different slots to the same signal as long as the argument lists will fit. For
example, the object that is used to signal the “end of page has been reached” might emit signals that
have, say, the box number in which the finished page can be found as a parameter (actually, the finished
page is always in box 255). Then one object could connect a method handle page(#1) to this signal,
another might connect the method emergency action(#1) to this signal, and so on.
Currently, it is not possible to “unregister” or “detach” a slot from a signal, that is, once an object has
been connect to a signal, it will continue to receive emissions of this signal till the end of the life-time
of the signal. This is even true when the object no longer exists (but the signal does), so care must be
taken that signal objects are always created before the objects that are listening to them.
Constructor signal()
The constructor does nothing.
Method connect(hobject handlei,hmethod namei)
This method gets an hobject handlei as parameter and a hmethod namei of this object. It will queue
the object-method pair in an internal list and each time the signal emits something, this object’s
method is called.
961
Be careful not to pass \pgfoothis as hobject handlei. This would cause the signal object to connect
to itself. Rather, if you wish to connect a signal to a method of the current object you first need
to create an alias using the get handle method:
\pgfooclass{some class}{
\method some class() {
\pgfoothis.get handle(\me)
\somesignal.connect(\me,foo)
\anothersignal.connect(\me,bar)
}
\method foo () {}
\method bar (#1,#2) {}
}
\pgfoonew \objA=new some class()
\pgfoonew \objB=new some class()
Method emit(hargumentsi)
This method emits a signal to all connected slots. This means that for all objects that have
previously been connected via a call of connect, the method (slot) that was specified during the
call of connect is invoked with given hargumentsi.
\anothersignal.emit(1,2)
% will call \objA.bar(1,2) and \objB.bar(1,2)
93.10
Implementation Notes
For the curious, here are some notes on how the oo-system is implemented:
• There is an object id counter that gets incremented each time an object is created. However, this
counter is local to the current scope, which means that it is reset at the end of each scope, corresponding
to the fact that at the end of a scope all objects created in this scope become invalid. Newly created
objects will then have the same id as “deleted” objects.
• Attributes are stored globally. For each attribute of each object there is a macro whose name is
composed of the object’s id and the attribute name. Changes to object attributes are always global.
• A call to the garbage collector causes a loop to be executed that tries to find objects whose object
number is larger than the current maximum alive objects. The global attributes of these objects are
then freed (set to \relax) by calling a special internal method of these (dead) objects.
The garbage collector is automatically called after each group in which an object was created using
\aftergroup.
• When a method is called, before the method call some code is executed that sets a global counter
storing the current object id to the object id of the object being called. After the method call some
code is inserted that restores the global counter to its original value. This is done without scopes,
so some tricky \expandafter magic is needed. Note that, because of this process, you cannot use
commands like \pgfutil@ifnextchar at the end of a method.
• An object handle contains just the code to set up and restore the current object number to the number
of the object being called.
962
Part IX
The Basic Layer
by Till Tantau
y(t)
3
x(t), y(t) = (t sin 1t , t cos 1t )
2
1
x(t)
−1
( π2 , 0)
2
−1
\begin{tikzpicture}
\draw[gray,very thin] (-1.9,-1.9) grid (2.9,3.9)
[step=0.25cm] (-1,-1) grid (1,1);
\draw[blue] (1,-2.1) -- (1,4.1); % asymptote
\draw[->] (-2,0) -- (3,0) node[right] {$x(t)$};
\draw[->] (0,-2) -- (0,4) node[above] {$y(t)$};
\foreach \pos in {-1,2}
\draw[shift={(\pos,0)}] (0pt,2pt) -- (0pt,-2pt) node[below] {$\pos$};
\foreach \pos in {-1,1,2,3}
\draw[shift={(0,\pos)}] (2pt,0pt) -- (-2pt,0pt) node[left] {$\pos$};
\fill (0,0) circle (0.064cm);
\draw[thick,parametric,domain=0.4:1.5,samples=200]
% The plot is reparameterised such that there are more samples
% near the center.
plot[id=asymptotic-example] function{(t*t*t)*sin(1/(t*t*t)),(t*t*t)*cos(1/(t*t*t))}
node[right] {$\bigl(x(t),y(t)\bigr) = (t\sin \frac{1}{t}, t\cos \frac{1}{t})$};
\fill[red] (0.63662,0) circle (2pt)
node [below right,fill=white,yshift=-4pt] {$(\frac{2}{\pi},0)$};
\end{tikzpicture}
963
94
Design Principles
This section describes the basic layer of pgf. This layer is built on top of the system layer. Whereas the
system layer just provides the absolute minimum for drawing graphics, the basic layer provides numerous
commands that make it possible to create sophisticated graphics easily and also quickly.
The basic layer does not provide a convenient syntax for describing graphics, which is left to frontends
like Tik Z. For this reason, the basic layer is typically used only by “other programs.” For example, the
beamer package uses the basic layer extensively, but does not need a convenient input syntax. Rather,
speed and flexibility are needed when beamer creates graphics.
The following basic design principles underlie the basic layer:
1. Structuring into a core and modules.
2. Consistently named TEX macros for all graphics commands.
3. Path-centered description of graphics.
4. Coordinate transformation system.
94.1
Core and Modules
The basic layer consists of a core package, called pgfcore, which provides the most basic commands, and several modules like commands for plotting (in the plot module). Modules are loaded using the \usepgfmodule
command.
If you say \usepackage{pgf} or \input pgf.tex or \usemodule[pgf], the plot and shapes modules
are preloaded (as well as the core and the system layer).
94.2
Communicating with the Basic Layer via Macros
In order to “communicate” with the basic layer you use long sequences of commands that start with \pgf. You
are only allowed to give these commands inside a {pgfpicture} environment. (Note that {tikzpicture}
opens a {pgfpicture} internally, so you can freely mix pgf commands and Tik Z commands inside a
{tikzpicture}.) It is possible to “do other things” between the commands. For example, you might
use one command to move to a certain point, then have a complicated computation of the next point, and
then move there.
\newdimen\myypos
\begin{pgfpicture}
\pgfpathmoveto{\pgfpoint{0cm}{\myypos}}
\pgfpathlineto{\pgfpoint{1cm}{\myypos}}
\advance \myypos by 1cm
\pgfpathlineto{\pgfpoint{1cm}{\myypos}}
\pgfpathclose
\pgfusepath{stroke}
\end{pgfpicture}
The following naming conventions are used in the basic layer:
1. All commands and environments start with pgf.
2. All commands that specify a point (a coordinate) start with \pgfpoint.
3. All commands that extend the current path start with \pgfpath.
4. All commands that set/change a graphics parameter start with \pgfset.
5. All commands that use a previously declared object (like a path, image or shading) start with \pgfuse.
6. All commands having to do with coordinate transformations start with \pgftransform.
7. All commands having to do with arrow tips start with \pgfarrows.
8. All commands for “quickly” extending or drawing a path start with \pgfpathq or \pgfusepathq.
9. All commands having to do with matrices start with \pgfmatrix.
964
94.3
Path-Centered Approach
In pgf the most important entity is the path. All graphics are composed of numerous paths that can be
stroked, filled, shaded, or clipped against. Paths can be closed or open, they can self-intersect and consist
of unconnected parts.
Paths are first constructed and then used. In order to construct a path, you can use commands starting
with \pgfpath. Each time such a command is called, the current path is extended in some way.
Once a path has been completely constructed, you can use it using the command \pgfusepath. Depending on the parameters given to this command, the path will be stroked (drawn) or filled or subsequent
drawings will be clipped against this path.
94.4
Coordinate Versus Canvas Transformations
pgf provides two transformation systems: pgf’s own coordinate transformation matrix and pdf’s or
PostScript’s canvas transformation matrix. These two systems are quite different. Whereas a scaling by a
factor of, say, 2 of the canvas causes everything to be scaled by this factor (including the thickness of lines
and text), a scaling of two in the coordinate system causes only the coordinates to be scaled, but not the
line width nor text.
By default, all transformations only apply to the coordinate transformation system. However, using the
command \pgflowlevel it is possible to apply a transformation to the canvas.
Coordinate transformations are often preferable over canvas transformations. Text and lines that are
transformed using canvas transformations suffer from differing sizes and lines whose thickness differs depending on whether the line is horizontal or vertical. To appreciate the difference, consider the following
two “circles” both of which have been scaled in the x-direction by a factor of 3 and by a factor of 0.5 in
the y-direction. The left circle uses a canvas transformation, the right uses pgf’s coordinate transformation
(some viewers will render the left graphic incorrectly since they do no apply the low-level transformation the
way they should):
coordinate
canvas
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95
Hierarchical Structures:
Package, Environments, Scopes, and Text
95.1
Overview
pgf uses two kinds of hierarchical structuring: First, the package itself is structured hierarchically, consisting
of different packages that are built on top of each other. Second, pgf allows you to structure your graphics
hierarchically using environments and scopes.
95.1.1
The Hierarchical Structure of the Package
The pgf system consists of several layers:
System layer. The lowest layer is called the system layer, though it might also be called “driver layer” or
perhaps “backend layer.” Its job is to provide an abstraction of the details of which driver is used
to transform the .dvi file. The system layer is implemented by the package pgfsys, which will load
appropriate driver files as needed.
The system layer is documented in Part X.
Basic layer. The basic layer is loaded by the package pgfcore and subsequent use of the command
\usepgfmodule to load additional modules of the basic layer.
The basic layer is documented in the present part.
Frontend layer. The frontend layer is not loaded by a single package. Rather, different packages, like Tik Z
or pgfpict2e, are different frontends to the basic layer.
The Tik Z frontend is documented in Part III.
Each layer will automatically load the necessary files of the layers below it.
In addition to the packages of these layers, there are also some library packages. These packages provide
additional definitions of things like new arrow tips or new plot handlers.
The library packages are documented in Part V.
95.1.2
The Hierarchical Structure of Graphics
Graphics in pgf are typically structured hierarchically. Hierarchical structuring can be used to identify
groups of graphical elements that are to be treated “in the same way.” For example, you might group
together a number of paths, all of which are to be drawn in red. Then, when you decide later on that you
like them to be drawn in, say, blue, all you have to do is to change the color once.
The general mechanism underlying hierarchical structuring is known as scoping in computer science.
The idea is that all changes to the general “state” of the graphic that are done inside a scope are local to
that scope. So, if you change the color inside a scope, this does not affect the color used outside the scope.
Likewise, when you change the line width in a scope, the line width outside is not changed, and so on.
There are different ways of starting and ending scopes of graphic parameters. Unfortunately, these scopes
are sometimes “in conflict” with each other and it is sometimes not immediately clear which scopes apply.
In essence, the following scoping mechanisms are available:
1. The “outermost” scope supported by pgf is the {pgfpicture} environment. All changes to the graphic
state done inside a {pgfpicture} are local to that picture.
In general, it is not possible to set graphic parameters globally outside any {pgfpicture} environments.
Thus, you can not say \pgfsetlinewidth{1pt} at the beginning of your document to have a default
line width of one point. Rather, you have to (re)set all graphic parameters inside each {pgfpicture}.
(If this is too bothersome, try defining some macro that does the job for you.)
2. Inside a {pgfpicture} you can use a {pgfscope} environment to keep changes of the graphic state
local to that environment.
The effect of commands that change the graphic state are local to the current {pgfscope}, but not
always to the current TEX group. Thus, if you open a TEX group (some text in curly braces) inside a
{pgfscope}, and if you change, for example, the dash pattern, the effect of this changed dash pattern
will persist till the end of the {pgfscope}.
966
Unfortunately, this is not always the case. Some graphic parameters only persist till the end of the
current TEX group. For example, when you use \pgfsetarrows to set the arrow tip inside a TEX
group, the effect lasts only till the end of the current TEX group.
3. Some graphic parameters are not scoped by {pgfscope} but “already” by TEX groups. For example,
the effect of coordinate transformation commands is always local to the current TEX group.
Since every {pgfscope} automatically creates a TEX group, all graphic parameters that are local to
the current TEX group are also local to the current {pgfscope}.
4. Some graphic parameters can only be scoped using TEX groups, since in some situations it is not
possible to introduce a {pgfscope}. For example, a path always has to be completely constructed and
used in the same {pgfscope}. However, we might wish to have different coordinate transformations
apply to different points on the path. In this case, we can use TEX groups to keep the effect local, but
we could not use {pgfscope}.
5. The \pgftext command can be used to create a scope in which TEX “escapes back” to normal TEX
mode. The text passed to the \pgftext is “heavily guarded” against having any effect on the scope
in which it is used. For example, it is possible to use another {pgfpicture} environment inside the
argument of \pgftext.
Most of the complications can be avoided if you stick to the following rules:
• Give graphic commands only inside {pgfpicture} environments.
• Use {pgfscope} to structure graphics.
• Do not use TEX groups inside graphics, except for keeping the effect of coordinate transformations
local.
95.2
The Hierarchical Structure of the Package
Before we come to the structuring commands provided by pgf to structure your graphics, let us first have
a look at the structure of the package itself.
95.2.1
The Core Package
To use pgf, include the following package:
\usepackage{pgfcore} % LATEX
\input pgfcore.tex
% plain TEX
\usemodule[pgfcore] % ConTEXt
This package loads the complete core of the “basic layer” of pgf, but not any modules. That is, it will
load all of the commands described in the current part of this manual, but it will not load frontends like
Tik Z. It will also load the system layer. To load additional modules, use the \usepgfmodule command
explained below.
The following package is just a convenience.
\usepackage{pgf} % LATEX
\input pgf.tex
% plain TEX
\usemodule[pgf] % ConTEXt
This package loads the pgfcore and the two modules shapes and plot.
In LATEX, the package takes two options:
\usepackage[draft]{pgf}
When this option is set, all images will be replaced by empty rectangles. This can speedup compilation.
\usepackage[version=hversion i]{pgf}
Indicates that the commands of version hversioni need to be defined. If you set hversioni to 0.65,
then a large bunch of “compatibility commands” are loaded. If you set hversioni to 0.96, then
these compatibility commands will not be loaded.
If this option is not given at all, then the commands of all versions are defined.
967
95.2.2
The Modules
\usepgflibrary{hmodule namesi}
Once the core has been loaded, you can use this command to load further modules. The modules in the
hmodule namesi list should be separated by commas. Instead of curly braces, you can also use square
brackets, which is something ConTEXt users will like. If you try to load a module a second time, nothing
will happen.
Example: \usepgfmodule{matrix,shapes}
What this command does is to load the file pgfmodulehmodulei.code.tex for each hmodulei in the
list of hmodule namesi. Thus, to write your own module, all you need to do is to place a file of the
appropriate name somewhere TEX can find it. LATEX, plain TEX, and ConTEXt users can then use your
library.
The following modules are available for use with pgfcore:
• The plot module provides commands for plotting functions. The commands are explained in Section 107.
• The shapes module provides commands for drawing shapes and nodes. These commands are explained
in Section 101.
• The decorations module provides commands for adding decorations to paths. These commands are
explained in Section 98.
• The matrix module provides the \pgfmatrix command. The commands are documented in Section 102.
95.2.3
The Library Packages
There is a special command for loading library packages. The difference between a library and module is the
following: A library just defines additional objects using the basic layer, whereas a module adds completely
new functionality. For instance, a decoration library defines additional decorations, while a decoration
module defines the whole code for handling decorations.
\usepgflibrary{hlist of librariesi}
Use this command to load further libraries. The list of libraries should contain the names of libraries
separated by commas. Instead of curly braces, you can also use square brackets. If you try to load a
library a second time, nothing will happen.
Example: \usepgflibrary{arrows}
This command causes the file pgflibraryhlibraryi.code.tex to be loaded for each hlibraryi in the hlist
of librariesi. This means that in order to write your own library file, place a file of the appropriate name
somewhere where TEX can find it. LATEX, plain TEX, and ConTEXt users can then use your library.
You should also consider adding a Tik Z library that simply includes your pgf library.
95.3
95.3.1
The Hierarchical Structure of the Graphics
The Main Environment
Most, but not all, commands of the pgf package must be given within a {pgfpicture} environment.
The only commands that (must) be given outside are commands having to do with including images (like
\pgfuseimage) and with inserting complete shadings (like \pgfuseshading). However, just to keep life
entertaining, the \pgfshadepath command must be given inside a {pgfpicture} environment.
\begin{pgfpicture}
henvironment contentsi
\end{pgfpicture}
This environment will insert a TEX box containing the graphic drawn by the henvironment contentsi at
the current position.
968
The size of the bounding box. The size of the box is determined in the following manner: While
pgf parses the henvironment contentsi, it keeps track of a bounding box for the graphic. Essentially,
this bounding box is the smallest box that contains all coordinates mentioned in the graphics. Some
coordinates may be “mentioned” by pgf itself; for example, when you add circle to the current path,
the support points of the curve making up the circle are also “mentioned” despite the fact that you will
not “see” them in your code.
Once the henvironment contentsi have been parsed completely, a TEX box is created whose size is the
size of the computed bounding box and this box is inserted at the current position.
Hello
World!
Hello \begin{pgfpicture}
\pgfpathrectangle{\pgfpointorigin}{\pgfpoint{2ex}{1ex}}
\pgfusepath{stroke}
\end{pgfpicture} World!
Sometimes, you may need more fine-grained control over the size of the bounding box. For example, the
computed bounding box may be too large or you intensionally wish the box to be “too small.” In these
cases, you can use the command \pgfusepath{use as bounding box}, as described in Section 99.6.
The baseline of the bounding box. When the box containing the graphic is inserted into the
normal text, the baseline of the graphic is normally at the bottom of the graphic. For this reason,
the following two sets of code lines have the same effect, despite the fact that the second graphic uses
“higher” coordinates than the first:
Rectangles
and
.
Rectangles \begin{pgfpicture}
\pgfpathrectangle{\pgfpointorigin}{\pgfpoint{2ex}{1ex}}
\pgfusepath{stroke}
\end{pgfpicture} and \begin{pgfpicture}
\pgfpathrectangle{\pgfpoint{0ex}{1ex}}{\pgfpoint{2ex}{1ex}}
\pgfusepath{stroke}
\end{pgfpicture}.
You can change the baseline using the \pgfsetbaseline command, see below.
Rectangles
and
.
Rectangles \begin{pgfpicture}
\pgfpathrectangle{\pgfpointorigin}{\pgfpoint{2ex}{1ex}}
\pgfusepath{stroke}
\pgfsetbaseline{0pt}
\end{pgfpicture} and \begin{pgfpicture}
\pgfpathrectangle{\pgfpoint{0ex}{1ex}}{\pgfpoint{2ex}{1ex}}
\pgfusepath{stroke}
\pgfsetbaseline{0pt}
\end{pgfpicture}.
Including text and images in a picture. You cannot directly include text and images in a picture.
Thus, you should not simply write some text in a {pgfpicture} or use a command like \includegraphics or even \pgfimage. In all these cases, you need to place the text inside a \pgftext command. This
will “escape back” to normal TEX mode, see Section 95.3.3 for details.
Remembering a picture position for later reference. After a picture has been typeset, its position
on the page is normally forgotten by pgf and also by TEX. This means that is not possible to reference
a node in this picture later on. In particular, it is normally impossible to draw lines between nodes in
different pictures automatically.
In order to make pgf “remember” a picture, the TEX-if \ifpgfrememberpicturepositiononpage should
be set to true. It is only important that this TEX-if is true at the end of the {pgfpicture}-environment,
so you can switch it on inside the environment. However, you can also just switch it on globally, then
the positions of all pictures are remembered.
There are several reasons why the remembering is not switched on by default. First, it does not work
for all backend drivers (currently, it works only for pdfTEX). Second, it requires two passes of TEX over
the file; on the first pass all positions will be wrong. Third, for every remembered picture a line is added
to the .aux-file, which may result in a large number of extra lines.
Despite all these “problems,” for documents that are processed with pdfTEX and in which there is only
a small number of pictures (less than a hundred or so), you can switch on this option globally, it will
not cause any significant slowing of TEX.
969
\pgfpicture
henvironment contentsi
\endpgfpicture
The plain TEX version of the environment. Note that in this version, also, a TEX group is created
around the environment.
\startpgfpicture
henvironment contentsi
\stoppgfpicture
This is the ConTEXt version of the environment.
\ifpgfrememberpicturepositiononpage
Determines whether the position of pictures on the page should be recorded. The value of this TEX-if
at the end of a {pgfpicture} environment is important, not the value at the beginning.
If this
page.
TEX.)
access
option is set to true of a picture, pgf will attempt to record the position of the picture on the
(This attempt will fail with most drivers and when it works, it typically requires two runs of
The position is not directly accessible. Rather, the nodes mechanism will use this position if you
a node from another picture. See Sections 101.3.2 and 17.13 for more details.
\pgfsetbaseline{hdimensioni}
This command specifies a y-coordinate of the picture that should be used as the baseline of the whole
picture. When a pgf picture has been typeset completely, pgf must decide at which height the baseline
of the picture should lie. Normally, the baseline is set to the y-coordinate of the bottom of the picture,
but it is often desirable to use a different height.
Text , , , .
Text
\begin{pgfpicture}
\pgfpathcircle{\pgfpointorigin}{1ex}\pgfusepath{stroke}
\end{pgfpicture},
\begin{pgfpicture}
\pgfsetbaseline{0pt}
\pgfpathcircle{\pgfpointorigin}{1ex}\pgfusepath{stroke}
\end{pgfpicture},
\begin{pgfpicture}
\pgfsetbaseline{.5ex}
\pgfpathcircle{\pgfpointorigin}{1ex}\pgfusepath{stroke}
\end{pgfpicture},
\begin{pgfpicture}
\pgfsetbaseline{-1ex}
\pgfpathcircle{\pgfpointorigin}{1ex}\pgfusepath{stroke}
\end{pgfpicture}.
\pgfsetbaselinepointnow{hpointi}
This command specifies the baseline indirectly, namely as the y-coordinate that the given hpointi has
when the command is called.
\pgfsetbaselinepointlater{hpointi}
This command also specifies the baseline indirectly, but the y-coordinate of the given hpointi is only
computed at the end of the picture.
Hello world.
95.3.2
Hello
\begin{pgfpicture}
\pgfsetbaselinepointlater{\pgfpointanchor{X}{base}}
% Note: no shape X, yet
\pgfnode{cross out}{center}{world.}{X}{\pgfusepath{stroke}}
\end{pgfpicture}
Graphic Scope Environments
Inside a {pgfpicture} environment you can substructure your picture using the following environment:
\begin{pgfscope}
970
henvironment contentsi
\end{pgfscope}
All changes to the graphic state done inside this environment are local to the environment. The graphic
state includes the following:
• The line width.
• The stroke and fill colors.
• The dash pattern.
• The line join and cap.
• The miter limit.
• The canvas transformation matrix.
• The clipping path.
Other parameters may also influence how graphics are rendered, but they are not part of the graphic
state. For example, the arrow tip kind is not part of the graphic state and the effect of commands
setting the arrow tip kind are local to the current TEX group, not to the current {pgfscope}. However,
since {pgfscope} starts and ends a TEX group automatically, a {pgfscope} can be used to limit the
effect of, say, commands that set the arrow tip kind.
\begin{pgfpicture}
\begin{pgfscope}
{
\pgfsetlinewidth{2pt}
\pgfpathrectangle{\pgfpointorigin}{\pgfpoint{2ex}{2ex}}
\pgfusepath{stroke}
}
\pgfpathrectangle{\pgfpoint{3ex}{0ex}}{\pgfpoint{2ex}{2ex}}
\pgfusepath{stroke}
\end{pgfscope}
\pgfpathrectangle{\pgfpoint{6ex}{0ex}}{\pgfpoint{2ex}{2ex}}
\pgfusepath{stroke}
\end{pgfpicture}
\begin{pgfpicture}
\begin{pgfscope}
{
\pgfsetarrows{-to}
\pgfpathmoveto{\pgfpointorigin}\pgfpathlineto{\pgfpoint{2ex}{2ex}}
\pgfusepath{stroke}
}
\pgfpathmoveto{\pgfpoint{3ex}{0ex}}\pgfpathlineto{\pgfpoint{5ex}{2ex}}
\pgfusepath{stroke}
\end{pgfscope}
\pgfpathmoveto{\pgfpoint{6ex}{0ex}}\pgfpathlineto{\pgfpoint{8ex}{2ex}}
\pgfusepath{stroke}
\end{pgfpicture}
At the start of the scope, the current path must be empty, that is, you cannot open a scope while
constructing a path.
It is usually a good idea not to introduce TEX groups inside a {pgfscope} environment.
\pgfscope
henvironment contentsi
\endpgfscope
Plain TEX version of the {pgfscope} environment.
\startpgfscope
henvironment contentsi
\stoppgfscope
This is the ConTEXt version of the environment.
The following scopes also encapsulate certain properties of the graphic state. However, they are typically
not used directly by the user.
971
\begin{pgfinterruptpath}
henvironment contentsi
\end{pgfinterruptpath}
This environment can be used to temporarily interrupt the construction of the current path. The effect
will be that the path currently under construction will be “stored away” and restored at the end of the
environment. Inside the environment you can construct a new path and do something with it.
An example application of this environment is the arrow tip caching. Suppose you ask pgf to use a
specific arrow tip kind. When the arrow tip needs to be rendered for the first time, pgf will “cache”
the path that makes up the arrow tip. To do so, it interrupts the current path construction and then
protocols the path of the arrow tip. The {pgfinterruptpath} environment is used to ensure that this
does not interfere with the path to which the arrow tips should be attached.
This command does not install a {pgfscope}. In particular, it does not call any \pgfsys@ commands
at all, which would, indeed, be dangerous in the middle of a path construction.
\pgfinterruptpath
henvironment contentsi
\endpgfinterruptpath
Plain TEX version of the environment.
\startpgfinterruptpath
henvironment contentsi
\stoppgfinterruptpath
ConTEXt version of the environment.
\begin{pgfinterruptpicture}
henvironment contentsi
\end{pgfinterruptpicture}
This environment can be used to temporarily interrupt a {pgfpicture}. However, the environment is
intended only to be used at the beginning and end of a box that is (later) inserted into a {pgfpicture}
using \pgfqbox. You cannot use this environment directly inside a {pgfpicture}.
Sub--picture.
\begin{pgfpicture}
\pgfpathmoveto{\pgfpoint{0cm}{0cm}} % In the middle of path, now
\newbox\mybox
\setbox\mybox=\hbox{
\begin{pgfinterruptpicture}
Sub-\begin{pgfpicture} % a subpicture
\pgfpathmoveto{\pgfpoint{1cm}{0cm}}
\pgfpathlineto{\pgfpoint{1cm}{1cm}}
\pgfusepath{stroke}
\end{pgfpicture}-picture.
\end{pgfinterruptpicture}
}
\pgfqbox{\mybox}%
\pgfpathlineto{\pgfpoint{0cm}{1cm}}
\pgfusepath{stroke}
\end{pgfpicture}\hskip3.9cm
\pgfinterruptpicture
henvironment contentsi
\endpgfinterruptpicture
Plain TEX version of the environment.
\startpgfinterruptpicture
henvironment contentsi
\stoppgfinterruptpicture
ConTEXt version of the environment.
\begin{pgfinterruptboundingbox}
henvironment contentsi
972
\end{pgfinterruptboundingbox}
This environment temporarily interrupts the computation of the bounding box and sets up a new
bounding box. At the beginning of the environment the old bounding box is saved and an empty
bounding box is installed. After the environment the original bounding box is reinstalled as if nothing
has happened.
\pgfinterruptboundingbox
henvironment contentsi
\endpgfinterruptboundingbox
Plain TEX version of the environment.
\startpgfinterruptboundingbox
henvironment contentsi
\stoppgfinterruptboundingbox
ConTEXt version of the environment.
95.3.3
Inserting Text and Images
Often, you may wish to add normal TEX text at a certain point inside a {pgfpicture}. You cannot do
so “directly,” that is, you cannot simply write this text inside the {pgfpicture} environment. Rather, you
must pass the text as an argument to the \pgftext command.
You must also use the \pgftext command to insert an image or a shading into a {pgfpicture}.
\pgftext[hoptionsi]{htexti}
This command will typeset htexti in normal TEX mode and insert the resulting box into the
{pgfpicture}. The bounding box of the graphic will be updated so that all of the text box is inside. By default, the text box is centered at the origin, but this can be changed either by giving
appropriate hoptionsi or by applying an appropriate coordinate transformation beforehand.
The htexti may contain verbatim text. (In other words, the htexti “argument” is not a normal argument,
but is put in a box and some \aftergroup hackery is used to find the end of the box.)
pgf’s current (high-level) coordinate transformation is synchronized with the canvas transformation
matrix temporarily when the text box is inserted. The effect is that if there is currently a high-level
rotation of, say, 30 degrees, the htexti will also be rotated by thirty degrees. If you do not want this
effect, you have to (possibly temporarily) reset the high-level transformation matrix.
The hoptionsi keys are used with the path /pgf/text/. The following keys are defined for this path:
(no value)
/pgf/text/left
The key causes the text box to be placed such that its left border is on the origin.
lovely
\tikz{\draw[help lines] (-1,-.5) grid (1,.5);
\pgftext[left] {lovely}}
(no value)
/pgf/text/right
The key causes the text box to be placed such that its right border is on the origin.
lovely
\tikz{\draw[help lines] (-1,-.5) grid (1,.5);
\pgftext[right] {lovely}}
(no value)
/pgf/text/right
This key causes the text box to be placed such that its top is on the origin. This option can be
used together with the left or right option.
lovely
\tikz{\draw[help lines] (-1,-.5) grid (1,.5);
\pgftext[top] {lovely}}
973
\tikz{\draw[help lines] (-1,-.5) grid (1,.5);
\pgftext[top,right] {lovely}}
lovely
(no value)
/pgf/text/bottom
This key causes the text box to be placed such that its bottom is on the origin.
lovely
\tikz{\draw[help lines] (-1,-.5) grid (1,.5);
\pgftext[bottom] {lovely}}
\tikz{\draw[help lines] (-1,-.5) grid (1,.5);
\pgftext[bottom,right] {lovely}}
lovely
(no value)
/pgf/text/base
This key causes the text box to be placed such that its baseline is on the origin.
lovely
\tikz{\draw[help lines] (-1,-.5) grid (1,.5);
\pgftext[base] {lovely}}
\tikz{\draw[help lines] (-1,-.5) grid (1,.5);
\pgftext[base,right] {lovely}}
lovely
(no default)
/pgf/text/at=hpointi
Translates the origin (that is, the point where the text is shown) to hpointi.
lovely
\tikz{\draw[help lines] (-1,-.5) grid (1,.5);
\pgftext[base,at={\pgfpoint{1cm}{0cm}}] {lovely}}
(no default)
/pgf/text/x=hdimensioni
Translates the origin by hdimensioni along the x-axis.
\tikz{\draw[help lines] (-1,-.5) grid (1,.5);
\pgftext[base,x=1cm,y=-0.5cm] {lovely}}
lovely
(no default)
/pgf/text/y=hdimensioni
This key works like the x option.
(no default)
/pgf/text/rotate=hdegreei
Rotates the coordinate system by hdegreei. This will also rotate the text box.
\tikz{\draw[help lines] (-1,-.5) grid (1,.5);
\pgftext[base,x=1cm,y=-0.5cm,rotate=30] {lovely}}
ely
lov
974
95.4
Error Messages and Warnings
Sometimes, a command inside pgf may fail. In this case, two commands are useful to communicate with
the author:
\pgferror{hmessagei}
Stops the processing of the current document and prints out the hmessagei. In LATEX, this will be done
using \PackageError, otherwise \errmessage is used directly.
\pgfwarning{hmessagei}
Prints the hmessagei on the output, but does not interrupt the processing. In LATEX, this will be done
using \PackageWarning, otherwise a write to stream 17 is used.
975
96
Specifying Coordinates
96.1
Overview
Most pgf commands expect you to provide the coordinates of a point (also called coordinate) inside your
picture. Points are always “local” to your picture, that is, they never refer to an absolute position on the
page, but to a position inside the current {pgfpicture} environment. To specify a coordinate you can use
commands that start with \pgfpoint.
96.2
Basic Coordinate Commands
The following commands are the most basic for specifying a coordinate.
\pgfpoint{hx coordinatei}{hy coordinatei}
Yields a point location. The coordinates are given as TEX dimensions.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfpathcircle{\pgfpoint{1cm}{1cm}} {2pt}
\pgfpathcircle{\pgfpoint{2cm}{5pt}} {2pt}
\pgfpathcircle{\pgfpoint{0pt}{.5in}}{2pt}
\pgfusepath{fill}
\end{tikzpicture}
\pgfpointorigin
Yields the origin. Same as \pgfpoint{0pt}{0pt}.
\pgfpointpolar{hdegreei}{hradiusi/hy-radiusi}
Yields a point location given in polar coordinates. You can specify the angle only in degrees, radians
are not supported, currently.
If the optional hy-radiusi is given, the polar coordinate is actually a coordinate on an ellipse whose
x-radius is given by hradiusi and whose y-radius is given by hy-radiusi.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\foreach \angle in {0,10,...,90}
{\pgfpathcircle{\pgfpointpolar{\angle}{1cm}}{2pt}}
\pgfusepath{fill}
\end{tikzpicture}
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\foreach \angle in {0,10,...,90}
{\pgfpathcircle{\pgfpointpolar{\angle}{1cm/2cm}}{2pt}}
\pgfusepath{fill}
\end{tikzpicture}
96.3
Coordinates in the XY-Coordinate System
Coordinates can also be specified as multiples of an x-vector and a y-vector. Normally, the x-vector points
one centimeter in the x-direction and the y-vector points one centimeter in the y-direction, but using the
commands \pgfsetxvec and \pgfsetyvec they can be changed. Note that the x- and y-vector do not
necessarily point “horizontally” and “vertically.”
\pgfpointxy{hsx i}{hsy i}
Yields a point that is situated at sx times the x-vector plus sy times the y-vector.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfpathmoveto{\pgfpointxy{1}{0}}
\pgfpathlineto{\pgfpointxy{2}{2}}
\pgfusepath{stroke}
\end{tikzpicture}
976
\pgfsetxvec{hpointi}
Sets that current x-vector for usage in the xyz-coordinate system.
Example:
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfpathmoveto{\pgfpointxy{1}{0}}
\pgfpathlineto{\pgfpointxy{2}{2}}
\pgfusepath{stroke}
\color{red}
\pgfsetxvec{\pgfpoint{0.75cm}{0cm}}
\pgfpathmoveto{\pgfpointxy{1}{0}}
\pgfpathlineto{\pgfpointxy{2}{2}}
\pgfusepath{stroke}
\end{tikzpicture}
\pgfsetyvec{hpointi}
Works like \pgfsetxvec.
\pgfpointpolarxy{hdegreei}{hradiusi/hy-radiusi}
This command is similar to the \pgfpointpolar command, but the hradiusi is now a factor to be
interpreted in the xy-coordinate system. This means that a degree of 0 is the same as the x-vector
of the xy-coordinate system times hradiusi and a degree of 90 is the y-vector times hradiusi. As for
\pgfpointpolar, a hradiusi can also be a pair separated by a slash. In this case, the x- and y-vectors
are multiplied by different factors.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\begin{scope}[x={(1cm,-5mm)},y=1.5cm]
\foreach \angle in {0,10,...,90}
{\pgfpathcircle{\pgfpointpolarxy{\angle}{1}}{2pt}}
\pgfusepath{fill}
\end{scope}
\end{tikzpicture}
96.4
Three Dimensional Coordinates
It is also possible to specify a point as a multiple of three vectors, the x-, y-, and z-vector. This is useful for
creating simple three dimensional graphics.
\pgfpointxyz{hsx i}{hsy i}{hsz i}
Yields a point that is situated at sx times the x-vector plus sy times the y-vector plus sz times the
z-vector.
\begin{pgfpicture}
\pgfsetarrowsend{to}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpointxyz{0}{0}{1}}
\pgfusepath{stroke}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpointxyz{0}{1}{0}}
\pgfusepath{stroke}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpointxyz{1}{0}{0}}
\pgfusepath{stroke}
\end{pgfpicture}
\pgfsetzvec{hpointi}
Works like \pgfsetxvec.
977
Inside the xyz-coordinate system, you can also specify points using spherical and cylindrical coordinates.
\pgfpointcylindrical{hdegreei}{hradiusi}{hheighti}
This command yields the same as
\pgfpointadd{\pgfpointpolarxy{degree}{radius}}{\pgfpointxyz{0}{0}{height}}
\begin{tikzpicture}
\draw [->] (0,0) -- (1,0,0) node [right] {$x$};
\draw [->] (0,0) -- (0,1,0) node [above] {$y$};
\draw [->] (0,0) -- (0,0,1) node [below left] {$z$};
y
x
z
\pgfpathcircle{\pgfpointcylindrical{80}{1}{.5}}{2pt}
\pgfusepath{fill}
\draw[red] (0,0) -- (0,0,.5) -- +(80:1);
\end{tikzpicture}
\pgfpointspherical{hlongitudei}{hlatitudei}{hradiusi}
This command yields a point “on the surface of the earth” specified by the hlongitudei and the hlatitudei.
The radius of the earth is given by hradiusi. The equator lies in the xy-plane.
\begin{tikzpicture}
\pgfsetfillcolor{lightgray}
\foreach \latitude in {-90,-75,...,30}
{
\foreach \longitude in {0,20,...,360}
{
\pgfpathmoveto{\pgfpointspherical{\longitude}{\latitude}{1}}
\pgfpathlineto{\pgfpointspherical{\longitude+20}{\latitude}{1}}
\pgfpathlineto{\pgfpointspherical{\longitude+20}{\latitude+15}{1}}
\pgfpathlineto{\pgfpointspherical{\longitude}{\latitude+15}{1}}
\pgfpathclose
}
\pgfusepath{fill,stroke}
}
\end{tikzpicture}
96.5
Building Coordinates From Other Coordinates
Many commands allow you to construct a coordinate in terms of other coordinates.
96.5.1
Basic Manipulations of Coordinates
\pgfpointadd{hv1 i}{hv2 i}
Returns the sum vector hv1 i + hv2 i.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfpathcircle{\pgfpointadd{\pgfpoint{1cm}{0cm}}{\pgfpoint{1cm}{1cm}}}{2pt}
\pgfusepath{fill}
\end{tikzpicture}
\pgfpointscale{hfactor i}{hcoordinatei}
Returns the vector hfactor ihcoordinatei.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfpathcircle{\pgfpointscale{1.5}{\pgfpoint{1cm}{0cm}}}{2pt}
\pgfusepath{fill}
\end{tikzpicture}
978
\pgfpointdiff{hstarti}{hend i}
Returns the difference vector hend i − hstarti.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfpathcircle{\pgfpointdiff{\pgfpoint{1cm}{0cm}}{\pgfpoint{1cm}{1cm}}}{2pt}
\pgfusepath{fill}
\end{tikzpicture}
\pgfpointnormalised{hpointi}
This command returns a normalised version of hpointi, that is, a vector of length 1pt pointing in the
direction of hpointi. If hpointi is the 0-vector or extremely short, a vector of length 1pt pointing upwards
is returned.
This command is not implemented by calculating the length of the vector, but rather by calculating
the angle of the vector and then using (something equivalent to) the \pgfpointpolar command. This
ensures that the point will really have length 1pt, but it is not guaranteed that the vector will precisely
point in the direction of hpointi due to the fact that the polar tables are accurate only up to one degree.
Normally, this is not a problem.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfpathcircle{\pgfpoint{2cm}{1cm}}{2pt}
\pgfpathcircle{\pgfpointscale{20}
{\pgfpointnormalised{\pgfpoint{2cm}{1cm}}}}{2pt}
\pgfusepath{fill}
\end{tikzpicture}
96.5.2
Points Traveling along Lines and Curves
The commands in this section allow you to specify points on a line or a curve. Imagine a point “traveling”
along a curve from some point p to another point q. At time t = 0 the point is at p and at time t = 1 it
is at q and at time, say, t = 1/2 it is “somewhere in the middle.” The exact location at time t = 1/2 will
not necessarily be the “halfway point,” that is, the point whose distance on the curve from p and q is equal.
Rather, the exact location will depend on the “speed” at which the point is traveling, which in turn depends
on the lengths of the support vectors in a complicated manner. If you are interested in the details, please
see a good book on Bézier curves.
\pgfpointlineattime{htime ti}{hpoint pi}{hpoint qi}
Yields a point that is the tth fraction between p and q, that is, p + t(q − p). For t = 1/2 this is the
middle of p and q.
1.25
1
0.75
0.5
0.25
0
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpoint{2cm}{2cm}}
\pgfusepath{stroke}
\foreach \t in {0,0.25,...,1.25}
{\pgftext[at=
\pgfpointlineattime{\t}{\pgfpointorigin}{\pgfpoint{2cm}{2cm}}]{\t}}
\end{tikzpicture}
\pgfpointlineatdistance{hdistancei}{hstart pointi}{hend pointi}
Yields a point that is located hdistancei many units away from the start point in the direction of the
end point. In other words, this is the point that results if we travel hdistancei steps from hstart pointi
towards hend pointi.
Example:
979
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpoint{3cm}{2cm}}
\pgfusepath{stroke}
\foreach \d in {0pt,20pt,40pt,70pt}
{\pgftext[at=
\pgfpointlineatdistance{\d}{\pgfpointorigin}{\pgfpoint{3cm}{2cm}}]{\d}}
\end{tikzpicture}
70pt
40pt
20pt
0pt
\pgfpointarcaxesattime{htime ti}{hcenter i}{h0-degree axisi}{h90-degree axisi}{hstart anglei}
{hend anglei}
Yields a point on the arc between hstart anglei and hend anglei on an ellipse whose center is at hcenter i
and whose two principal axes are h0-degree axisi and h90-degree axisi. For t = 0 the point at the hstart
anglei is returned and for t = 1 the point at the hend anglei.
1 0.75
0.5
0.25
0
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfpathmoveto{\pgfpoint{2cm}{1cm}}
\pgfpatharcaxes{0}{60}{\pgfpoint{2cm}{0cm}}{\pgfpoint{0cm}{1cm}}
\pgfusepath{stroke}
\foreach \t in {0,0.25,0.5,0.75,1}
{\pgftext[at=\pgfpointarcaxesattime{\t}{\pgfpoint{0cm}{1cm}}
{\pgfpoint{2cm}{0cm}}{\pgfpoint{0cm}{1cm}}{0}{60}]{\t}}
\end{tikzpicture}
\pgfpointcurveattime{htime ti}{hpoint pi}{hpoint s1 i}{hpoint s2 i}{hpoint qi}
Yields a point that is on the Bézier curve from p to q with the support points s1 and s2 . The time t is
used to determine the location, where t = 0 yields p and t = 1 yields q.
0.5
0.25
0
96.5.3
0.75
1
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfpathmoveto{\pgfpointorigin}
\pgfpathcurveto
{\pgfpoint{0cm}{2cm}}{\pgfpoint{0cm}{2cm}}{\pgfpoint{3cm}{2cm}}
\pgfusepath{stroke}
\foreach \t in {0,0.25,0.5,0.75,1}
{\pgftext[at=\pgfpointcurveattime{\t}{\pgfpointorigin}
{\pgfpoint{0cm}{2cm}}
{\pgfpoint{0cm}{2cm}}
{\pgfpoint{3cm}{2cm}}]{\t}}
\end{tikzpicture}
Points on Borders of Objects
The following commands are useful for specifying a point that lies on the border of special shapes. They are
used, for example, by the shape mechanism to determine border points of shapes.
\pgfpointborderrectangle{hdirection pointi}{hcorner i}
This command returns a point that lies on the intersection of a line starting at the origin and going
towards the point hdirection pointi and a rectangle whose center is in the origin and whose upper right
corner is at hcorner i.
The hdirection pointi should have length “about 1pt,” but it will be normalized automatically. Nevertheless, the “nearer” the length is to 1pt, the less rounding errors.
980
\begin{tikzpicture}
\draw[help lines] (0,0) grid (2,1.5);
\pgfpathrectanglecorners{\pgfpoint{-1cm}{-1.25cm}}{\pgfpoint{1cm}{1.25cm}}
\pgfusepath{stroke}
\pgfpathcircle{\pgfpoint{5pt}{5pt}}{2pt}
\pgfpathcircle{\pgfpoint{-10pt}{5pt}}{2pt}
\pgfusepath{fill}
\color{red}
\pgfpathcircle{\pgfpointborderrectangle
{\pgfpoint{5pt}{5pt}}{\pgfpoint{1cm}{1.25cm}}}{2pt}
\pgfpathcircle{\pgfpointborderrectangle
{\pgfpoint{-10pt}{5pt}}{\pgfpoint{1cm}{1.25cm}}}{2pt}
\pgfusepath{fill}
\end{tikzpicture}
\pgfpointborderellipse{hdirection pointi}{hcorner i}
This command works like the corresponding command for rectangles, only this time the hcorner i is the
corner of the bounding rectangle of an ellipse.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (2,1.5);
\pgfpathellipse{\pgfpointorigin}{\pgfpoint{1cm}{0cm}}{\pgfpoint{0cm}{1.25cm}}
\pgfusepath{stroke}
\pgfpathcircle{\pgfpoint{5pt}{5pt}}{2pt}
\pgfpathcircle{\pgfpoint{-10pt}{5pt}}{2pt}
\pgfusepath{fill}
\color{red}
\pgfpathcircle{\pgfpointborderellipse
{\pgfpoint{5pt}{5pt}}{\pgfpoint{1cm}{1.25cm}}}{2pt}
\pgfpathcircle{\pgfpointborderellipse
{\pgfpoint{-10pt}{5pt}}{\pgfpoint{1cm}{1.25cm}}}{2pt}
\pgfusepath{fill}
\end{tikzpicture}
96.5.4
Points on the Intersection of Lines
\pgfpointintersectionoflines{hpi}{hqi}{hsi}{hti}
This command returns the intersection of a line going through p and q and a line going through s and
t. If the lines do not intersection, an arithmetic overflow will occur.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (2,2);
\draw (.5,0) -- (2,2);
\draw (1,2) -- (2,0);
\pgfpathcircle{%
\pgfpointintersectionoflines
{\pgfpointxy{.5}{0}}{\pgfpointxy{2}{2}}
{\pgfpointxy{1}{2}}{\pgfpointxy{2}{0}}}
{2pt}
\pgfusepath{stroke}
\end{tikzpicture}
96.5.5
Points on the Intersection of Two Circles
\pgfpointintersectionofcircles{hp1 i}{hp2 i}{hr1 i}{hr2 i}{hsolutioni}
This command returns the intersection of the two circles centered at p1 and p2 with radii r1 and r2 . If
hsolutioni is 1, the first intersection is returned, otherwise the second one is returned.
981
\begin{tikzpicture}
\draw[help lines] (0,0) grid (2,2);
\draw (0.5,0) circle (1);
\draw (1.5,1) circle (.8);
\pgfpathcircle{%
\pgfpointintersectionofcircles
{\pgfpointxy{.5}{0}}{\pgfpointxy{1.5}{1}}
{1cm}{0.8cm}{1}}
{2pt}
\pgfusepath{stroke}
\end{tikzpicture}
96.5.6
Points on the Intersection of Two Paths
Tik Z Library intersections
\usepgflibrary{intersections}
\usepgflibrary[intersections]
\usetikzlibrary{intersections}
\usetikzlibrary[intersections]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library defines the below command and allows you to calculate the intersections of two arbitrary
paths. However, due to the low accuracy of TEX, the paths should not be “too complicated”. In
particular, you should not try to intersect paths consisting of lots of very small segments such as plots
or decorated paths.
\pgfintersectionofpaths{hpath 1 i}{hpath 2 i}
This command finds the intersection points on the paths hpath 1 i and hpath 2 i. The number of intersection points (“solutions”) that are found will be stored, and each point can be accessed afterward.
The code for hpath 1 i and hpath 2 i is executed within a TEX group and so can contain transformations
(which will be in addition to any existing transformations). The code should not use the path in any
way, unless the path is saved first and restored afterward. pgf will regard solutions as “a bit special”,
in that the points returned will be “absolute” and unaffected by any further transformations.
\begin{pgfpicture}
\pgfintersectionofpaths
{
\pgfpathellipse{\pgfpointxy{0}{0}}{\pgfpointxy{1}{0}}{\pgfpointxy{0}{2}}
\pgfgetpath\temppath
\pgfusepath{stroke}
\pgfsetpath\temppath
}
{
\pgftransformrotate{-30}
\pgfpathrectangle{\pgfpointorigin}{\pgfpointxy{2}{2}}
\pgfgetpath\temppath
\pgfusepath{stroke}
\pgfsetpath\temppath
}
\foreach \s in {1,...,\pgfintersectionsolutions}
{\pgfpathcircle{\pgfpointintersectionsolution{\s}}{2pt}}
\pgfusepath{stroke}
\end{pgfpicture}
\pgfintersectionsolutions
After using the \pgfintersectionofpaths command, this TEX-macro will indicate the number of
solutions found.
\pgfpointintersectionsolution{hnumber i}
After using the \pgfintersectionofpaths command, this command will return the point for
solution hnumber i or the origin if this solution was not found. By default, the intersections are
simply returned in the order that the intersection algorithm finds them. Unfortunately, this is not
necessarily a “helpful” ordering. However the following two commands can be used to order the
solutions more helpfully.
982
\pgfintersectionsortbyfirstpath
Using this command will mean the solutions will be sorted along hpath 1 i.
\pgfintersectionsortbysecondpath
Using this command will mean the solutions will be sorted along hpath 2 i.
96.6
Extracting Coordinates
There are two commands that can be used to “extract” the x- or y-coordinate of a coordinate.
\pgfextractx{hdimensioni}{hpointi}
Sets the TEX-hdimensioni to the x-coordinate of the point.
\newdimen\mydim
\pgfextractx{\mydim}{\pgfpoint{2cm}{4pt}}
%% \mydim is now 2cm
\pgfextracty{hdimensioni}{hpointi}
Like \pgfextractx, except for the y-coordinate.
\pgfgetlastxy{hmacro for xi}{hmacro for yi}
Stores the most recently used (x, y) coordinates into two macros.
Macro x is ‘56.9055pt’ and macro y is ‘113.81102pt’.
\pgfpoint{2cm}{4cm}
\pgfgetlastxy{\macrox}{\macroy}
Macro $x$ is ‘\macrox’ and macro $y$ is ‘\macroy’.
Since (x, y) coordinates are usually assigned globally, it is safe to use this command after path operations.
96.7
Internals of How Point Commands Work
As a normal user of pgf you do not need to read this section. It is relevant only if you need to understand
how the point commands work internally.
When a command like \pgfpoint{1cm}{2pt} is called, all that happens is that the two TEX-dimension
variables \pgf@x and \pgf@y are set to 1cm and 2pt, respectively. These variables belong to the set of
internal pgf registers, see section 111 for details. A command like \pgfpathmoveto that takes a coordinate
as parameter will just execute this parameter and then use the values of \pgf@x and \pgf@y as the coordinates
to which it will move the pen on the current path.
Since commands like \pgfpointnormalised modify other variables besides \pgf@x and \pgf@y during
the computation of the final values of \pgf@x and \pgf@y, it is a good idea to enclose a call of a command
like \pgfpoint in a TEX-scope and then make the changes of \pgf@x and \pgf@y global as in the following
example:
...
{ % open scope
\pgfpointnormalised{\pgfpoint{1cm}{1cm}}
\global\pgf@x=\pgf@x % make the change of \pgf@x persist past the scope
\global\pgf@y=\pgf@y % make the change of \pgf@y persist past the scope
}
% \pgf@x and \pgf@y are now set correctly, all other variables are
% unchanged
Since this situation arises very often, the macro \pgf@process can be used to perform the above code:
\pgf@process{hcodei}
Executes the hcodei in a scope and then makes \pgf@x and \pgf@y global.
Note that this macro is used often internally. For this reason, it is not a good idea to keep anything important in the variables \pgf@x and \pgf@y since they will be overwritten and changed frequently. Instead, intermediate values can ge stored in the TEX-dimensions \pgf@xa, \pgf@xb, \pgf@xc and their y-counterparts
\pgf@ya, \pgf@yb, pgf@yc. For example, here is the code of the command \pgfpointadd:
983
\def\pgfpointadd#1#2{%
\pgf@process{#1}%
\pgf@xa=\pgf@x%
\pgf@ya=\pgf@y%
\pgf@process{#2}%
\advance\pgf@x by\pgf@xa%
\advance\pgf@y by\pgf@ya}
984
97
Constructing Paths
97.1
Overview
The “basic entity of drawing” in pgf is the path. A path consists of several parts, each of which is either
a closed or open curve. An open curve has a starting point and an end point and, in between, consists of
several segments, each of which is either a straight line or a Bézier curve. Here is an example of a path (in
red) consisting of two parts, one open, one closed:
part 2 (closed)
end part 1
end first segment
straight segment
start part 1
\begin{tikzpicture}[scale=2]
\draw[thick,red]
(0,0) coordinate (a)
-- coordinate (ab) (1,.5) coordinate (b)
.. coordinate (bc) controls +(up:1cm) and +(left:1cm) .. (3,1)
(0,1) -- (2,1) -- coordinate (x) (1,2) -- cycle;
coordinate (c)
\draw (a) node[below] {start part 1}
(ab) node[below right] {straight segment}
(b) node[right] {end first segment}
(c) node[right] {end part 1}
(x) node[above right] {part 2 (closed)};
\end{tikzpicture}
A path, by itself, has no “effect,” that is, it does not leave any marks on the page. It is just a set of
points on the plane. However, you can use a path in different ways. The most natural actions are stroking
(also known as drawing) and filling. Stroking can be imagined as picking up a pen of a certain diameter and
“moving it along the path.” Filling means that everything “inside” the path is filled with a uniform color.
Naturally, the open parts of a path must first be closed before a path can be filled.
In pgf, there are numerous commands for constructing paths, all of which start with \pgfpath. There
are also commands for using paths, though most operations can be performed by calling \pgfusepath with
an appropriate parameter.
As a side-effect, the path construction commands keep track of two bounding boxes. One is the bounding
box for the current path, the other is a bounding box for all paths in the current picture. See Section 97.13
for more details.
Each path construction command extends the current path in some way. The “current path” is a global
entity that persists across TEX groups. Thus, between calls to the path construction commands you can
perform arbitrary computations and even open and close TEX groups. The current path only gets “flushed”
when the \pgfusepath command is called (or when the soft-path subsystem is used directly, see Section 115).
97.2
The Move-To Path Operation
The most basic operation is the move-to operation. It must be given at the beginning of paths, though some
path construction command (like \pgfpathrectangle) generate move-tos implicitly. A move-to operation
can also be used to start a new part of a path.
\pgfpathmoveto{hcoordinatei}
This command expects a pgf-coordinate like \pgfpointorigin as its parameter. When the current
path is empty, this operation will start the path at the given hcoordinatei. If a path has already been
partly constructed, this command will end the current part of the path and start a new one.
985
\begin{pgfpicture}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpoint{1cm}{1cm}}
\pgfpathlineto{\pgfpoint{2cm}{1cm}}
\pgfpathlineto{\pgfpoint{3cm}{0.5cm}}
\pgfpathlineto{\pgfpoint{3cm}{0cm}}
\pgfsetfillcolor{yellow!80!black}
\pgfusepath{fill,stroke}
\end{pgfpicture}
\begin{pgfpicture}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpoint{1cm}{1cm}}
\pgfpathlineto{\pgfpoint{2cm}{1cm}}
\pgfpathmoveto{\pgfpoint{2cm}{1cm}} % New part
\pgfpathlineto{\pgfpoint{3cm}{0.5cm}}
\pgfpathlineto{\pgfpoint{3cm}{0cm}}
\pgfsetfillcolor{yellow!80!black}
\pgfusepath{fill,stroke}
\end{pgfpicture}
The command will apply the current coordinate transformation matrix to hcoordinatei before using it.
It will update the bounding box of the current path and picture, if necessary.
97.3
The Line-To Path Operation
\pgfpathlineto{hcoordinatei}
This command extends the current path in a straight line to the given hcoordinatei. If this command
is given at the beginning of path without any other path construction command given before (in particular without a move-to operation), the TEX file may compile without an error message, but a viewer
application may display an error message when trying to render the picture.
\begin{pgfpicture}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpoint{1cm}{1cm}}
\pgfpathlineto{\pgfpoint{2cm}{1cm}}
\pgfsetfillcolor{yellow!80!black}
\pgfusepath{fill,stroke}
\end{pgfpicture}
The command will apply the current coordinate transformation matrix to hcoordinatei before using it.
It will update the bounding box of the current path and picture, if necessary.
97.4
The Curve-To Path Operations
\pgfpathcurveto{hsupport 1 i}{hsupport 2 i}{hcoordinatei}
This command extends the current path with a Bézier curve from the last point of the path to
hcoordinatei. The hsupport 1 i and hsupport 2 i are the first and second support point of the Bézier
curve. For more information on Bézier curves, please consult a standard textbook on computer graphics.
Like the line-to command, this command may not be the first path construction command in a path.
\begin{pgfpicture}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathcurveto
{\pgfpoint{1cm}{1cm}}{\pgfpoint{2cm}{1cm}}{\pgfpoint{3cm}{0cm}}
\pgfsetfillcolor{yellow!80!black}
\pgfusepath{fill,stroke}
\end{pgfpicture}
The command will apply the current coordinate transformation matrix to hcoordinatei before using it.
It will update the bounding box of the current path and picture, if necessary. However, the bounding
box is simply made large enough such that it encompasses all of the support points and the hcoordinatei.
This will guarantee that the curve is completely inside the bounding box, but the bounding box will
986
typically be quite a bit too large. It is not clear (to me) how this can be avoided without resorting to
“some serious math” in order to calculate a precise bounding box.
\pgfpathquadraticcurveto{hsupporti}{hcoordinatei}
This command works like \pgfpathcurveto, only it uses a quadratic Bézier curve rather than a cubic
one. This means that only one support point is needed.
\begin{pgfpicture}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathquadraticcurveto
{\pgfpoint{1cm}{1cm}}{\pgfpoint{2cm}{0cm}}
\pgfsetfillcolor{yellow!80!black}
\pgfusepath{fill,stroke}
\end{pgfpicture}
Internally, the quadratic curve is converted into a cubic curve. The only noticeable effect of this is that
the points used for computing the bounding box are the control points of the converted curve rather
than hsupporti. The main effect of this is that the bounding box will be a bit tighter than might be
expected. In particular, hsupporti will not always be part of the bounding box.
There exist two commands to draw only part of a cubic Bézier curve:
\pgfpathcurvebetweentime{htime t1 i}{htime t2 i}{hpoint pi}{hpoint s1 i}{hpoint s2 i}{hpoint qi}
This command draws the part of the curve described by p, s1 , s2 and q between the times t1 and t2 . A
time value of 0 indicates the point p and a time value of 1 indicates point q. This command includes a
moveto operation to the first point.
\begin{tikzpicture}
\draw [thin] (0,0) .. controls (0,2) and (3,0) .. (3,2);
\pgfpathcurvebetweentime{0.25}{0.9}{\pgfpointxy{0}{0}}{\pgfpointxy{0}{2}}
{\pgfpointxy{3}{0}}{\pgfpointxy{3}{2}}
\pgfsetstrokecolor{red}
\pgfsetstrokeopacity{0.5}
\pgfsetlinewidth{2pt}
\pgfusepath{stroke}
\end{tikzpicture}
\pgfpathcurvebetweentimecontinue{htime t1 i}{htime t2 i}{hpoint pi}{hpoint s1 i}{hpoint s2 i}{hpoint qi}
This command works like \pgfpathcurvebetweentime, except that a moveto operation is not made to
the first point.
97.5
The Close Path Operation
\pgfpathclose
This command closes the current part of the path by appending a straight line to the start point of the
current part. Note that there is a difference between closing a path and using the line-to operation to
add a straight line to the start of the current path. The difference is demonstrated by the upper corners
of the triangles in the following example:
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfsetlinewidth{5pt}
\pgfpathmoveto{\pgfpoint{1cm}{1cm}}
\pgfpathlineto{\pgfpoint{0cm}{-1cm}}
\pgfpathlineto{\pgfpoint{1cm}{-1cm}}
\pgfpathclose
\pgfpathmoveto{\pgfpoint{2.5cm}{1cm}}
\pgfpathlineto{\pgfpoint{1.5cm}{-1cm}}
\pgfpathlineto{\pgfpoint{2.5cm}{-1cm}}
\pgfpathlineto{\pgfpoint{2.5cm}{1cm}}
\pgfusepath{stroke}
\end{tikzpicture}
987
97.6
Arc, Ellipse and Circle Path Operations
The path construction commands that we have discussed up to now are sufficient to create all paths that
can be created “at all.” However, it is useful to have special commands to create certain shapes, like circles,
that arise often in practice.
In the following, the commands for adding (parts of) (transformed) circles to a path are described.
\pgfpatharc{hstart anglei}{hend anglei}{hradiusiandhy-radiusi}
This command appends a part of a circle (or an ellipse) to the current path. Imagine the curve between
hstart anglei and hend anglei on a circle of radius hradiusi (if hstart anglei < hend anglei, the curve
goes around the circle counterclockwise, otherwise clockwise). This curve is now moved such that the
point where the curve starts is the previous last point of the path. Note that this command will not
start a new part of the path, which is important for example for filling purposes.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpoint{0cm}{1cm}}
\pgfpatharc{180}{90}{.5cm}
\pgfpathlineto{\pgfpoint{3cm}{1.5cm}}
\pgfpatharc{90}{-45}{.5cm}
\pgfusepath{fill}
\end{tikzpicture}
Saying \pgfpatharc{0}{360}{1cm} “nearly” gives you a full circle. The “nearly” refers to the fact that
the circle will not be closed. You can close it using \pgfpathclose.
If the optional hy-radiusi is given, the hradiusi is the x-radius and the hy-radiusi the y-radius of the
ellipse from which the curve is taken:
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfpathmoveto{\pgfpointorigin}
\pgfpatharc{180}{45}{2cm and 1cm}
\pgfusepath{draw}
\end{tikzpicture}
The axes of the circle or ellipse from which the arc is “taken” always point up and right. However, the
current coordinate transformation matrix will have an effect on the arc. This can be used to, say, rotate
an arc:
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgftransformrotate{30}
\pgfpathmoveto{\pgfpointorigin}
\pgfpatharc{180}{45}{2cm and 1cm}
\pgfusepath{draw}
\end{tikzpicture}
The command will update the bounding box of the current path and picture, if necessary. Unless
rotation or shearing transformations are applied, the bounding box will be tight.
\pgfpatharcaxes{hstart anglei}{hend anglei}{hfirst axisi}{hsecond axisi}
This command is similar to \pgfpatharc. The main difference is how the ellipse or circle is specified
from which the arc is taken. The two parameters hfirst axisi and hsecond axisi are the 0◦ -axis and the
90◦ -axis of the ellipse from which the path is taken. Thus, \pgfpatharc{0}{90}{1cm and 2cm} has
the same effect as
\pgfpatharcaxes{0}{90}{\pgfpoint{1cm}{0cm}}{\pgfpoint{0cm}{2cm}}
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw (0,0) -- (2cm,5mm) (0,0) -- (0cm,1cm);
\pgfpathmoveto{\pgfpoint{2cm}{5mm}}
\pgfpatharcaxes{0}{90}{\pgfpoint{2cm}{5mm}}{\pgfpoint{0cm}{1cm}}
\pgfusepath{draw}
\end{tikzpicture}
988
\pgfpatharcto{hx-radiusi}{hy-radiusi}{hrotationi} {hlarge arc flagi}{hcounterclockwise flagi}
{htarget pointi}
This command (which directly corresponds to the arc-path command of svg) is used to add an arc to
the path that starts at the current point and ends at htarget pointi. This arc is part of an ellipse that is
determined in the following way: Imagine an ellipse with radii hx-radiusi and hy-radiusi that is rotated
around its center by hrotationi degrees. When you move this ellipse around in the plane, there will be
exactly two positions such that the two current point and the target point lie on the border of the ellipse
(excluding pathological cases). The flags hlarge arc flagi and hclockwise flagi are then used to decide
which of these ellipses should be picked and which arc on the picked ellipsis should be used.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfpathmoveto{\pgfpoint{0mm}{20mm}}
\pgfpatharcto{3cm}{1cm}{0}{0}{0}{\pgfpoint{3cm}{1cm}}
\pgfusepath{draw}
\end{tikzpicture}
Both flags are considered to be false exactly if they evaluate to 0, otherwise they are true. If the hlarge
arc flagi is true, then the angle spanned by the arc will be greater than 180◦ , otherwise it will be less
than 180◦ . The hclockwise flagi is used to determine which of the two ellipses should be used: if the
flag is true, then the arc goes from the current point to the target point in a counterclockwise direction,
otherwise in a clockwise fashion.
\begin{tikzpicture}
\pgfsetlinewidth{2pt}
% Flags 0 0: red
\pgfsetstrokecolor{red}
\pgfpathmoveto{\pgfpointorigin}
\pgfpatharcto{20pt}{10pt}{0}{0}{0}{\pgfpoint{20pt}{10pt}}
\pgfusepath{stroke}
% Flags 0 1: blue
\pgfsetstrokecolor{blue}
\pgfpathmoveto{\pgfpointorigin}
\pgfpatharcto{20pt}{10pt}{0}{0}{1}{\pgfpoint{20pt}{10pt}}
\pgfusepath{stroke}
% Flags 1 0: orange
\pgfsetstrokecolor{orange}
\pgfpathmoveto{\pgfpointorigin}
\pgfpatharcto{20pt}{10pt}{0}{1}{0}{\pgfpoint{20pt}{10pt}}
\pgfusepath{stroke}
% Flags 1 1: black
\pgfsetstrokecolor{black}
\pgfpathmoveto{\pgfpointorigin}
\pgfpatharcto{20pt}{10pt}{0}{1}{1}{\pgfpoint{20pt}{10pt}}
\pgfusepath{stroke}
\end{tikzpicture}
Warning: The internal computations necessary for this command are numerically very unstable. In
particular, the arc will not always really end at the htarget coordinatei, but may be off by up to several
points. A more precise positioning is currently infeasible due to TEX’s numerical weaknesses. The only
case it works quite nicely is when the resulting angle is a multiple of 90◦ .
\pgfpatharctoprecomputed{hcenter pointi}{hstart anglei}{hend anglei}{hend pointi}
{hx-radiusi}{hy-radiusi}{hratio x-radius/y-radiusi}{hratio y-radius/x-radiusi}
A specialized arc operation which is fast and numerically stable, provided a lot of information is given
in advance.
In contrast to \pgfpatharc, it explicitly interpolates start and end points.
In contrast to \pgfpatharcto, this routine is numerically stable and quite fast since it relies on a lot of
available information.
989
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\def\cx{1.5cm}% center x
\def\cy{1cm}% center y
\def\startangle{0}%
\def\endangle{270}%
\def\a{1.5cm}% xradius
\def\b{0.5cm}% yradius
\pgfmathparse{\a/\b}\let\abratio=\pgfmathresult
\pgfmathparse{\b/\a}\let\baratio=\pgfmathresult
%
% start point:
\pgfpathmoveto{\pgfpoint{\cx+\a*cos(\startangle)}{\cy+\b*sin(\startangle)}}%
\pgfpatharctoprecomputed
{\pgfpoint{\cx}{\cy}}
{\startangle}
{\endangle}
{\pgfpoint{\cx+\a*cos(\endangle)}{\cy+\b*sin(\endangle)}}% end point
{\a}
{\b}
{\abratio}
{\baratio}
\pgfusepath{draw}
\end{tikzpicture}
\pgfpatharctomaxstepsize
The quality of arc approximation taken by \pgfpatharctoprecomputed by means of Bézier splines
is controlled by a mesh width, which is initially
\def\pgfpatharctoprecomputed{45}.
The mesh width is provided in (full!) degrees. The smaller the mesh width, the more precise the
arc approximation.
Use an empty value to disable spline approximation (uses a single cubic polynomial for the complete
arc).
The value must be an integer!
\pgfpathellipse{hcenter i}{hfirst axisi}{hsecond axisi}
The effect of this command is to append an ellipse to the current path (if the path is not empty, a
new part is started). The ellipse’s center will be hcenter i and hfirst axisi and hsecond axisi are the
axis vectors. The same effect as this command can also be achieved using an appropriate sequence of
move-to, arc, and close operations, but this command is easier and faster.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfpathellipse{\pgfpoint{1cm}{0cm}}
{\pgfpoint{1.5cm}{0cm}}
{\pgfpoint{0cm}{1cm}}
\pgfusepath{draw}
\color{red}
\pgfpathellipse{\pgfpoint{1cm}{0cm}}
{\pgfpoint{1cm}{1cm}}
{\pgfpoint{-0.5cm}{0.5cm}}
\pgfusepath{draw}
\end{tikzpicture}
The command will apply coordinate transformations to all coordinates of the ellipse. However, the
coordinate transformations are applied only after the ellipse is “finished conceptually.” Thus, a transformation of 1cm to the right will simply shift the ellipse one centimeter to the right; it will not add
1cm to the x-coordinates of the two axis vectors.
The command will update the bounding box of the current path and picture, if necessary.
\pgfpathcircle{hcenter i}{hradiusi}
A shorthand for \pgfpathellipse applied to hcenter i and the two axis vectors (hradiusi, 0) and
(0, hradiusi).
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97.7
Rectangle Path Operations
Another shape that arises frequently is the rectangle. Two commands can be used to add a rectangle to the
current path. Both commands will start a new part of the path.
\pgfpathrectangle{hcorner i}{hdiagonal vector i}
Adds a rectangle to the path whose one corner is hcorner i and whose opposite corner is given by
hcorner i + hdiagonal vector i.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfpathrectangle{\pgfpoint{1cm}{0cm}}{\pgfpoint{1.5cm}{1cm}}
\pgfpathrectangle{\pgfpoint{1.5cm}{0.25cm}}{\pgfpoint{1.5cm}{1cm}}
\pgfpathrectangle{\pgfpoint{2cm}{0.5cm}}{\pgfpoint{1.5cm}{1cm}}
\pgfusepath{draw}
\end{tikzpicture}
The command will apply coordinate transformations and update the bounding boxes tightly.
\pgfpathrectanglecorners{hcorner i}{hopposite corner i}
Adds a rectangle to the path whose two opposing corners are hcorner i and hopposite corner i.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfpathrectanglecorners{\pgfpoint{1cm}{0cm}}{\pgfpoint{1.5cm}{1cm}}
\pgfusepath{draw}
\end{tikzpicture}
The command will apply coordinate transformations and update the bounding boxes tightly.
97.8
The Grid Path Operation
\pgfpathgrid[hoptionsi]{hfirst corner i}{hsecond corner i}
Appends a grid to the current path. That is, a (possibly large) number of parts are added to the path,
each part consisting of a single horizontal or vertical straight line segment.
Conceptually, the origin is part of the grid and the grid is clipped to the rectangle specified by the hfirst
corner i and the hsecond corner i. However, no clipping occurs (this command just adds parts to the
current path) and the points where the lines enter and leave the “clipping area” are computed and used
to add simple lines to the current path.
The following keys influence the grid:
(no default, initially 1cm)
/pgf/stepx=hdimensioni
The horizontal stepping.
(no default, initially 1cm)
/pgf/stepy=hdimensioni
The vertical stepping.
/pgf/step=hvector i
(no default)
Sets the horizontal stepping to the x-coordinate of hvector i and the vertical stepping to its
y-coordinate.
\begin{pgfpicture}
\pgfsetlinewidth{0.8pt}
\pgfpathgrid[step={\pgfpoint{1cm}{1cm}}]
{\pgfpoint{-3mm}{-3mm}}{\pgfpoint{33mm}{23mm}}
\pgfusepath{stroke}
\pgfsetlinewidth{0.4pt}
\pgfpathgrid[stepx=1mm,stepy=1mm]
{\pgfpoint{-1.5mm}{-1.5mm}}{\pgfpoint{31.5mm}{21.5mm}}
\pgfusepath{stroke}
\end{pgfpicture}
991
The command will apply coordinate transformations and update the bounding boxes. As for ellipses,
the transformations are applied to the “conceptually finished” grid.
\begin{pgfpicture}
\pgftransformrotate{10}
\pgfpathgrid[stepx=1mm,stepy=2mm]{\pgfpoint{0mm}{0mm}}{\pgfpoint{30mm}{30mm}}
\pgfusepath{stroke}
\end{pgfpicture}
97.9
The Parabola Path Operation
\pgfpathparabola{hbend vector i}{hend vector i}
This command appends two half-parabolas to the current path. The first starts at the current point and
ends at the current point plus hbend vector i. At this point, it has its bend. The second half parabola
starts at that bend point and ends at point that is given by the bend plus hend vector i.
If you set hend vector i to the null vector, you append only a half parabola that goes from the current
point to the bend; by setting hbend vector i to the null vector, you append only a half parabola that
goes through the current point and hend vector i and has its bend at the current point.
It is not possible to use this command to draw a part of a parabola that does not contain the bend.
\begin{pgfpicture}
% Half-parabola going ‘‘up and right’’
\pgfpathmoveto{\pgfpointorigin}
\pgfpathparabola{\pgfpointorigin}{\pgfpoint{2cm}{4cm}}
\color{red}
\pgfusepath{stroke}
% Half-parabola going ‘‘down and right’’
\pgfpathmoveto{\pgfpointorigin}
\pgfpathparabola{\pgfpoint{-2cm}{4cm}}{\pgfpointorigin}
\color{blue}
\pgfusepath{stroke}
% Full parabola
\pgfpathmoveto{\pgfpoint{-2cm}{2cm}}
\pgfpathparabola{\pgfpoint{1cm}{-1cm}}{\pgfpoint{2cm}{4cm}}
\color{orange}
\pgfusepath{stroke}
\end{pgfpicture}
The command will apply coordinate transformations and update the bounding boxes.
97.10
Sine and Cosine Path Operations
Sine and cosine curves often need to be drawn and the following commands may help with this. However,
they only allow you to append sine and cosine curves in intervals that are multiples of π/2.
\pgfpathsine{hvector i}
This command appends a sine curve in the interval [0, π/2] to the current path. The sine curve is
squeezed or stretched such that the curve starts at the current point and ends at the current point plus
hvector i.
992
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,1);
\pgfpathmoveto{\pgfpoint{1cm}{0cm}}
\pgfpathsine{\pgfpoint{1cm}{1cm}}
\pgfusepath{stroke}
\color{red}
\pgfpathmoveto{\pgfpoint{1cm}{0cm}}
\pgfpathsine{\pgfpoint{-2cm}{-2cm}}
\pgfusepath{stroke}
\end{tikzpicture}
The command will apply coordinate transformations and update the bounding boxes.
\pgfpathcosine{hvector i}
This command appends a cosine curve in the interval [0, π/2] to the current path. The curve is squeezed
or stretched such that the curve starts at the current point and ends at the current point plus hvector i.
Using several sine and cosine operations in sequence allows you to produce a complete sine or cosine
curve
\begin{pgfpicture}
\pgfpathmoveto{\pgfpoint{0cm}{0cm}}
\pgfpathsine{\pgfpoint{1cm}{1cm}}
\pgfpathcosine{\pgfpoint{1cm}{-1cm}}
\pgfpathsine{\pgfpoint{1cm}{-1cm}}
\pgfpathcosine{\pgfpoint{1cm}{1cm}}
\pgfsetfillcolor{yellow!80!black}
\pgfusepath{fill,stroke}
\end{pgfpicture}
The command will apply coordinate transformations and update the bounding boxes.
97.11
Plot Path Operations
There exist several commands for appending plots to a path. These commands are available through the
module plot. They are documented in Section 107.
97.12
Rounded Corners
Normally, when you connect two straight line segments or when you connect two curves that end and start
“at different angles,” you get “sharp corners” between the lines or curves. In some cases it is desirable to
produce “rounded corners” instead. Thus, the lines or curves should be shortened a bit and then connected
by arcs.
pgf offers an easy way to achieve this effect, by calling the following two commands.
\pgfsetcornersarced{hpointi}
This command causes all subsequent corners to be replaced by little arcs. The effect of this command
lasts till the end of the current TEX scope.
The hpointi dictates how large the corner arc will be. Consider a corner made by two lines l and r and
assume that the line l comes first on the path. The x-dimension of the hpointi decides by how much the
line l will be shortened, the y-dimension of hpointi decides by how much the line r will be shortened.
Then, the shortened lines are connected by an arc.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfsetcornersarced{\pgfpoint{5mm}{5mm}}
\pgfpathrectanglecorners{\pgfpointorigin}{\pgfpoint{3cm}{2cm}}
\pgfusepath{stroke}
\end{tikzpicture}
993
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfsetcornersarced{\pgfpoint{10mm}{5mm}}
% 10mm entering,
% 5mm leaving.
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpoint{0cm}{2cm}}
\pgfpathlineto{\pgfpoint{3cm}{2cm}}
\pgfpathcurveto
{\pgfpoint{3cm}{0cm}}
{\pgfpoint{2cm}{0cm}}
{\pgfpoint{1cm}{0cm}}
\pgfusepath{stroke}
\end{tikzpicture}
If the x- and y-coordinates of hpointi are the same and the corner is a right angle, you will get a perfect
quarter circle (well, not quite perfect, but perfect up to six decimals). When the angle is not 90◦ , you
only get a fair approximation.
More or less “all” corners will be rounded, even the corner generated by a \pgfpathclose command.
(The author is a bit proud of this feature.)
\begin{pgfpicture}
\pgfsetcornersarced{\pgfpoint{4pt}{4pt}}
\pgfpathmoveto{\pgfpointpolar{0}{1cm}}
\pgfpathlineto{\pgfpointpolar{72}{1cm}}
\pgfpathlineto{\pgfpointpolar{144}{1cm}}
\pgfpathlineto{\pgfpointpolar{216}{1cm}}
\pgfpathlineto{\pgfpointpolar{288}{1cm}}
\pgfpathclose
\pgfusepath{stroke}
\end{pgfpicture}
To return to normal (unrounded) corners, use \pgfsetcornersarced{\pgfpointorigin}.
Note that the rounding will produce strange and undesirable effects if the lines at the corners are too
short. In this case the shortening may cause the lines to “suddenly extend over the other end” which is
rarely desirable.
97.13
Internal Tracking of Bounding Boxes for Paths and Pictures
The path construction commands keep track of two bounding boxes: One for the current path, which is reset
whenever the path is used and thereby flushed, and a bounding box for the current {pgfpicture}.
\pgfresetboundingbox
Resets the picture’s bounding box. The picture will simply forget any previous bounding box updates
and start collecting from scratch.
You can use this together with \pgfusepath{use as bounding box} to replace the bounding box by
the one of a particular path (ignoring subsequent paths).
The bounding boxes are not accessible by “normal” macros. Rather, two sets of four dimension variables
are used for this, all of which contain the letter @.
\pgf@pathminx
The minimum x-coordinate “mentioned” in the current path. Initially, this is set to 16000pt.
\pgf@pathmaxx
The maximum x-coordinate “mentioned” in the current path. Initially, this is set to −16000pt.
\pgf@pathminy
The minimum y-coordinate “mentioned” in the current path. Initially, this is set to 16000pt.
\pgf@pathmaxy
The maximum y-coordinate “mentioned” in the current path. Initially, this is set to −16000pt.
994
\pgf@picminx
The minimum x-coordinate “mentioned” in the current picture. Initially, this is set to 16000pt.
\pgf@picmaxx
The maximum x-coordinate “mentioned” in the current picture. Initially, this is set to −16000pt.
\pgf@picminy
The minimum y-coordinate “mentioned” in the current picture. Initially, this is set to 16000pt.
\pgf@picmaxy
The maximum y-coordinate “mentioned” in the current picture. Initially, this is set to −16000pt.
Each time a path construction command is called, the above variables are (globally) updated. To facilitate
this, you can use the following command:
\pgf@protocolsizes{hx-dimensioni}{hy-dimensioni}
Updates all of the above dimensions in such a way that the point specified by the two arguments
is inside both bounding boxes. For the picture’s bounding box this updating occurs only if \ifpgf@relevantforpicturesize is true, see below.
For the bounding box of the picture it is not always desirable that every path construction command
affects this bounding box. For example, if you have just used a clip command, you do not want anything
outside the clipping area to affect the bounding box. For this reason, there exists a special “TEX if” that
(locally) decides whether updating should be applied to the picture’s bounding box. Clipping will set this if
to false, as will certain other commands.
\pgf@relevantforpicturesizefalse
Suppresses updating of the picture’s bounding box.
\pgf@relevantforpicturesizetrue
Causes updating of the picture’s bounding box.
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98
Decorations
\usepgfmodule{decorations}
\usepgfmodule[decorations]
% LATEX and plain TEX and pure pgf
% ConTEXt and pure pgf
The commands for creating decorations are defined in this module, so you need to load this module to
use decorations. This module is automatically loaded by the different decoration libraries.
98.1
Overview
Decorations are a general way of creating graphics by “moving along” a path and, while doing so, either
drawing something or constructing a new path. This could be as simple as extending a path with a “zigzagged”
line. . .
\tikz \draw decorate[decoration=zigzag] {(0,0) -- (3,0)};
. . . but could also be as complex as typesetting text along a path:
Some
\tikz \path decorate [decoration={text along
te
xt
path,
text={Some text along a path}}]
{ (0,2) .. controls (2,2) and (1,0) .. (3,0) };
ng
alo
a
pat
h
The workflow for using decorations is the following:
1. You define a decoration using the \pgfdeclaredecoration command. Different useful decorations are
already declared in libraries like decorations.shapes.
2. You use normal path construction commands like \pgfpathlineto to construct a path. Let us call
this path the to-be-decorated path.
3. You place the path construction commands inside the environment {pgfdecoration}. This environment takes the name of a previously declared decoration as a parameter. It will then start “walking
along” the to-be-decorated path. As it does this, a special finite automaton called a decoration automaton produces new path commands as its output (or even other outputs). These outputs replace the
to-be-decorated path; indeed, after the to-be-decorated path has been fully walked along it is thrown
away, only the output of the automaton persists.
In the present section the process of how decoration automata work is explained first. Then the command(s) for declaring decoration automata and for using them are covered.
98.2
Decoration Automata
Decoration automata (and the closely related meta-decoration automata) are a general concept for creating
graphics “along paths.” For straight lines, this idea was first proposed by Till Tantau in an earlier version
of pgf, the idea to extend this to arbitrary path was proposed and implemented by Mark Wibrow. Further
versatility is provided by “meta-decorations”. These are automata that decorate a path with decorations.
In the present subsection the different ideas underlying decoration automata are presented.
98.2.1
The Different Paths
In order to prevent confusion with different types of paths, such as those that are extended, those that are
decorated and those that are created, the following conventions will be used:
• The preexisting path refers to the current path in existence before a decoration environment. (Possibly
this path has been created by another decoration used earlier, but we will still call this path the
preexisting path also in this case.)
• The input path refers to the to-be-decorated path that the decoration automaton moves along. The
input path may consist of many line and curve input segments (for example, a circle or an ellipse
consists of four curves). It is specified inside the decoration environment.
996
• The output path refers to the path that the decoration creates. Depending on the decoration, this
path may or may not be empty (a decoration can also choose to use side-effects instead of producing
an output path). The input path is always consumed by the decoration automaton, that is, it is no
longer available in any way after the decoration automaton has finished.
The effect of a decoration environment is the following: The input path, which is specified inside the
environment, is constructed and stored. This process does not alter the preexisting path in any way. Then
the decoration automaton is started (as described later) and it produces an output path (possibly empty).
Whenever part of the output path is produced, it is concatenated with the preexisting path. After the
environment, the current path will equal the original preexisting path followed by the output path.
It is permissible that a decoration issues a \pgfusepath command. As usual, this causes the current
path to be filled or stroked or some other action to be taken and the current path is set to the empty path.
As described above, when the decoration automaton starts, the current path is the preexisting path and as
the automaton progresses, the current path is constantly being extended by the output path. This means
that first time a \pgfusepath command is used on a decoration, the preexisting path is part of the path
this command operates on; in subsequent calls only the part of the output path constructed since the last
\pgfusepath command will be used.
You can use this mechanism to stroke or fill different parts of the output path in different colors, line
widths, fills and shades; all within the same decoration. Alternatively, a decoration can choose to produce
no output path at all: the text decoration simply typesets text along a path.
98.2.2
Segments and States
The most common use of a decoration is to “repeat something along a path” (for example, the zigzag
decoration repeats
along a path). However, it not necessarily the case that only one thing is repeated: a
decoration can consist of different parts, or segments, repeated in a particular order.
When you declare a decoration, you provide a description of how their different segments will be rendered.
The description of each segment should be given in a way as if the “x-axis” of the segment is the tangent to
the path at a particular point, and that point is the origin of the segment. Thus, for example, the segment
of the zigzag decoration might be defined using the following code:
\pgfpathlineto{\pgfpoint{5pt}{5pt}}
\pgfpathlineto{\pgfpoint{15pt}{-5pt}}
\pgfpathlineto{\pgfpoint{20pt}{0pt}}
pgf will ensure that an appropriate coordinate transformation is in place when the segment is rendered
such that the segment actually points in the right direction. Also, subsequent segments will be transformed
such that they are “further along the path” toward the end of the path. All transformations are set up
automatically.
Note that we did not use a \pgfpathmoveto{\pgfpointorigin} at the beginning of the segment code.
Doing so would subdivide the path into numerous subpaths. Rather, we assume that the previous segment
caused the current point to be at the origin.
The width of a segment can (and must) be specified explicitly. pgf will use this width to find out the
start point of the next segment and the correct rotation. The width the you provide need not be the “real”
width of the segment, which allows decoration segments to overlap or to be spaced far apart.
The zigzag decoration only has one segment that is repeated again and again. However, we might also
like to have different segments and use rules to describe which segment should be used where. For example,
we might have special segments at the start and at the end.
Decorations use a mechanism known in theoretical in computer science as finite state automata to describe
which segment is used at a particular point. The idea is the following: For the first segment we start in
a special state called the initial state. In this state, and also in all other states later, pgf first computes
how much space is left on the input path. That is, pgf keeps track of the distance to the end of the input
path. Attached to each state there is a set of rules of the following form: “If the remaining distance on the
input path is less than x, switch to state q.” pgf checks for each of these rules whether it applies and, if so,
immediately switches to state q.
Only if none of the rules tell us to switch to another state, pgf will execute the state’s code. This
code will (typically) add a segment to the output path. In addition to the rules there is also a width
parameter attached to each state. pgf then translates the coordinate system by this width and reduces the
remaining distance on the input path. Then, pgf either stays in the current state or switches to another
state, depending on yet another property attached of the state.
997
The whole process stops when a special state called final is reached. The segment of this state is
immediately added to the output path (it is often empty, though) and the process ends.
98.3
Declaring Decorations
The following command is used to declare a decoration. Essentially, this command describes the decoration
automaton.
\pgfdeclaredecoration{hnamei}{hinitial statei}{hstatesi}
This command declares a new decoration called hnamei. The hstatesi argument contains a description
of the decoration automaton’s states and the transitions between them. The hinitial statei is the state
in which the automaton starts.
When the automaton is later applied to an input path, it keeps track of a certain position on the input
path. This current point will “travel along the path,” each time being moved along by a certain distance.
This will also work if the path is not a straight line. That is, it is permissible that the path curves
are veers at a sharp angle. It is also permissible that while traveling along the input path, the current
input segment ends and a new input segment starts. In this case, the remaining distance on the first
input segment is subtracted from the hdimensioni and then we travel along the second input segment
for the remaining distance. This input segment may also end early, in which case we travel along the
next input segment, and so on. Note that it cannot happen that we travel past the end of the input
path since this would have caused an immediate switch to the final state.
Note that the computation of the path lengths has only a low accuracy because of TEX’s small math
capabilities. Do not expect high accuracy alignments when using decorations (unless the input path
consists only of horizontal and vertical lines).
The hstatesi argument should consist of \state commands, one for each state of the decoration automaton. The \state command is defined only when the hstatesi argument is executed.
\state{hnamei}[hoptionsi]{hcodei}
This command declares a new state inside the current decoration automaton. The state is named
hnamei.
When the decoration automaton is in state hnamei, the following things happen:
1. The hoptionsi are parsed. This may lead to a state switch, see below. When this happens, the
following steps are not executed. The hoptionsi are executed one after the other in the given
order. If an option causes a state switch, the switch is immediate, even if later options might
cause a different state switch.
2. The hcodei is executed in a TEX-group with the current transformation matrix set up in such a
way that the origin is on the input path at the current point (the point at the distance traveled
up to now) and the coordinate system is rotated in such a way that the positive x-axis points
in the direction of the tangent to the input path at the current point, while the positive y-axis
points to the left of this tangent.
As described earlier, the hcodei can have two different effects: If it just contains path construction commands, the decoration will produce an output path, that is, it extends the preexisting
path. Here is an example:
998
\pgfdeclaredecoration{example}{initial}
{
\state{initial}[width=10pt]
{
\pgfpathlineto{\pgfpoint{0pt}{5pt}}
\pgfpathlineto{\pgfpoint{5pt}{5pt}}
\pgfpathlineto{\pgfpoint{5pt}{-5pt}}
\pgfpathlineto{\pgfpoint{10pt}{-5pt}}
\pgfpathlineto{\pgfpoint{10pt}{0pt}}
}
\state{final}
{
\pgfpathlineto{\pgfpointdecoratedpathlast}
}
}
\tikz[decoration=example]
{
\draw [decorate]
(0,0) -- (3,0);
\draw [red,decorate] (0,0) to [out=45,in=135] (3,0);
}
Alternatively, the hcodei can also contain the \pgfusepath command. This will use the path
in the usual manner, where “the path” is the preexisting path plus a part of the output path
for the first invocation and the different parts of the rest of the output path for the following
invocation. Here is an example:
\pgfdeclaredecoration{stars}{initial}{
\state{initial}[width=15pt]
{
\pgfmathparse{round(rnd*100)}
\pgfsetfillcolor{yellow!\pgfmathresult!orange}
\pgfsetstrokecolor{yellow!\pgfmathresult!red}
\pgfnode{star}{center}{}{}{\pgfusepath{stroke,fill}}
}
\state{final}
{
\pgfpathmoveto{\pgfpointdecoratedpathlast}
}
}
\tikz\path[decorate, decoration=stars, star point ratio=2, star points=5,
inner sep=0, minimum size=rnd*10pt+2pt]
(0,0) .. controls (0,2) and (3,2) .. (3,0)
.. controls (3,-3) and (0,0) .. (0,-3)
.. controls (0,-5) and (3,-5) .. (3,-3);
3. After the hcodei has been executed (possibly more than once, if the repeat state option is
used), the state switches to whatever state has been specified inside the hoptionsi using the
next state option. If no next state has been specified, the state stays the same.
The hoptionsi are executed with the key path set to /pgf/decoration automaton. The following
keys are defined:
/pgf/decoration automaton/switch if less than=hdimensioni to hnew statei (no default)
When this key is encountered, pgf checks whether the remaining distance to the end of the
input path is less than hdimensioni. If so, an immediate state switch to hnew statei occurs.
/pgf/decoration automaton/switch if input segment less than=
hdimensioni to hnew statei
(no default)
When this key is encountered, pgf checks whether the remaining distance to the end of the
current input segment of the input path is less than hdimensioni. If so, an immediate state
switch to hnew statei occurs.
/pgf/decoration automaton/width=hdimensioni
(no default)
First, this option causes an immediate switch to the state final if the remaining distance
on the input path is less than hdimensioni. The effect is the same as if you had said
switch if less than=hdimensioni to final just before the width option.
999
If no switch occurs, this option tells pgf the width of the segment. The current point will
travel along the input path (as described earlier) by this distance.
/pgf/decoration automaton/repeat state=hrepetitionsi
(no default, initially 0)
Tells pgf how long the automaton stays “normally” in the current state. This count is reset to
hrepetitionsi each time one of the switch if keys causes a state switch. If no state switches
occur, the hcodei is executed and the repetition counter is decreased. Then, there is once more
a chance of a state change caused by any of the hoptionsi. If no repetition occurs, the hcodei is
executed once more and the counter is decreased once more. When the counter reaches zero,
the hcodei is executed once more, but, then, a different state is entered, as specified by the
next state option.
Note, that the maximum number of times the state will be executed is hrepetitionsi + 1.
/pgf/decoration automaton/next state=hnew statei
(no default)
After the hcodei for state has been executed for the last time, a state switch to hnew statei is
performed. If this option is not given, the next state is the same as the current state.
/pgf/decoration automaton/if input segment is closepath=hoptionsi
(no default)
This key checks whether the current input segment is a closepath operation. If so, the hoptionsi
get executed; otherwise nothing happens. You can use this option to handle a closepath in
some special way, for instance, switching to a new state in which \pgfpathclose is executed.
/pgf/decoration automaton/auto end on length=hdimensioni
(no default)
This key is just included for convenience, it does nothing that cannot be achieved using the
previous options. The effect is the following: If the remaining input path’s length is at most
hdimensioni, the decorated path is ended with a straight line to the end of the input path and,
possibly, it is closed, namely if the input path ended with a closepath operation. Otherwise, it
is checked whether the current input segment is a closepath segment and whether the remaining
distance on the current input segment is at most hdistancei. If so, then a closepath operation is
used to close the decorated path and the automaton continues with the next subpath, remaining
in the current state.
In all other cases, nothing happens.
/pgf/decoration automaton/auto corner on length=hdimensioni
(no default)
This key has the following effect: Firstly, in case the TEX-if \ifpgfdecoratepathhascorners
is false, nothing happens. Otherwise, it is tested whether the remaining distance on the current
input segment is at most hdimensioni. If so, a lineto operation is used to reach the end of
this input segment and the automaton continues with the next input segment, but remains in
the current state.
The main idea behind this option is to avoid having decoration segments “overshoot” past a
corner.
You may sometimes wish to do computations outside the transformational TEX-group of the current
segment, so that these results of these computations are available in the next state. For this, the
following two options are useful:
/pgf/decoration automaton/persistent precomputation=hprecodei
(no default)
If the hcodei of the state is executed, the hprecodei is executed first and it is executed outside
the TEX-group of the hcodei. Note that when the hprecodei is executed, the transformation
matrix is not set up.
/pgf/decoration automaton/persistent postcomputation=hpostcodei
(no default)
Works like the persistent precomputation option, only the hpostcodei is executed after (and
also outside) the TEX-group of the main hcodei.
There are a number of macros and dimensions which may be useful inside a decoration automaton.
The following macros are available:
\pgfdecoratedpathlength
The length of the input path. If the input path consists of several input segments, this number
is the sum of the lengths of the input segments.
1000
\pgfdecoratedinputsegmentlength
The length of the current input segment of the input path. “Current input segment” refers to
the input segment on which the current point lies.
\pgfpointdecoratedpathlast
The final point of the input path.
\pgfpointdecoratedinputsegmentlast
The final point of the current input segment of the input path.
\pgfdecoratedangle
The angle of the tangent to the decorated path at the origin of the current segment. The
transformation matrix applied at the beginning of a state includes a rotation equivalent to this
angle.
The following TEX dimension registers are also available inside the automaton:
\pgfdecoratedremainingdistance
The remaining distance on the input path.
\pgfdecoratedcompleteddistance
The completed distance on the input path.
\pgfdecoratedinputsegmentremainingdistance
The remaining distance on the current input segment of the input path.
\pgfdecoratedinputsegmentcompleteddistance
The completed distance on the current input segment of the input path.
Further keys and macros are defined and used by the decoration libraries, see Section 48.
The following example shows how these options can be used:
1001
\pgfdeclaredecoration{complicated example decoration}{initial}
{
\state{initial}[width=5pt,next state=up]
{ \pgfpathlineto{\pgfpoint{5pt}{0pt}} }
\state{up}[width=5pt,next state=down]
{
\ifdim\pgfdecoratedremainingdistance>\pgfdecoratedcompleteddistance
% Growing
\pgfpathlineto{\pgfpoint{0pt}{\pgfdecoratedcompleteddistance}}
\pgfpathlineto{\pgfpoint{5pt}{\pgfdecoratedcompleteddistance}}
\pgfpathlineto{\pgfpoint{5pt}{0pt}}
\else
% Shrinking
\pgfpathlineto{\pgfpoint{0pt}{\pgfdecoratedremainingdistance}}
\pgfpathlineto{\pgfpoint{5pt}{\pgfdecoratedremainingdistance}}
\pgfpathlineto{\pgfpoint{5pt}{0pt}}
\fi%
}
\state{down}[width=5pt,next state=up]
{
\ifdim\pgfdecoratedremainingdistance>\pgfdecoratedcompleteddistance
% Growing
\pgfpathlineto{\pgfpoint{0pt}{-\pgfdecoratedcompleteddistance}}
\pgfpathlineto{\pgfpoint{5pt}{-\pgfdecoratedcompleteddistance}}
\pgfpathlineto{\pgfpoint{5pt}{0pt}}
\else
% Shrinking
\pgfpathlineto{\pgfpoint{0pt}{-\pgfdecoratedremainingdistance}}
\pgfpathlineto{\pgfpoint{5pt}{-\pgfdecoratedremainingdistance}}
\pgfpathlineto{\pgfpoint{5pt}{0pt}}
\fi%
}
\state{final}
{
\pgfpathlineto{\pgfpointdecoratedpathlast}
}
}
\begin{tikzpicture}[decoration=complicated example decoration]
\draw decorate{ (0,0) -- (3,0)};
\fill [red!50,rounded corners=2pt]
decorate {(.5,-2) -- ++(2.5,-2.5)} -- (3,-5) -| (0,-2) -- cycle;
\end{tikzpicture}
98.3.1
Predefined Decorations
The three decorations moveto, lineto, and curveto are predefined and “always available.” They are mostly
useful in conjunction with meta-decorations. They are documented in Section 48 alongside the other decorations.
98.4
Using Decorations
Once a decoration has been declared, it can be used.
\begin{pgfdecoration}{hdecoration listi}
henvironment contentsi
\end{pgfdecoration}
The henvironment contentsi should contain commands for creating an path. This path is the basis for
the input paths for the decorations in the hdecoration listi. In detail, the following happens:
1. The preexisting unused path is saved.
2. The path commands specified in henvironment contentsi are executed and this resulting path is
saved. The path is then divided into different input paths as follows: The format for each item in
{hdecoration listi} is
{hdecorationi}{hlengthi}{hbefore codei}{hafter codei}
The hbefore codei and the hafter codei are optional. The input path is divided into input paths
as follows: The first input path consists of the first lines of the path specified in the henvironment
1002
contentsi until the hlengthi of the first element of the hdecoration listi is reached. If this length
is reached in the middle of a line, the line is broken up at this exact position. Then the second
input path has the hlengthi of the second element in the hdecoration listi and consists of the lines
making up the following hlengthi part of the path in the henvironment contentsi, and so on.
If the lengths in the hdecoration listi do not add up to the total length of the path in the
henvironment contentsi, either some decorations are dropped (if their lengths add up to more
than the length of the henvironment contentsi) or the input path is not fully used (if their lengths
add up to less).
3. The preexisting path is reinstalled.
4. The decoration automata move along the input paths, thus creating (and possibly using) the output
paths. These output paths extend the current path (unless they are used).
Some important points should be noted regarding the use of this environment:
• If henvironment contentsi does not begin with \pgfpathmoveto, the last known point on the
preexisting path is assumed as the starting point.
• All except the last of any sequence of consecutive move-to commands in henvironment contentsi
are discarded.
• Any move-to commands at the end of henvironment contentsi are ignored.
• Any close-path commands on the input path are interpreted as straight lines. Internally, something
a little more complicated is going on, however, a closed path on the input path has no effect on the
output path, other than causing the automaton to travel in a straight line towards the location of
the last move-to command on the input path.
• Although tangent computations for the input path work with the last point on the preexisting path,
no automatic move-to operations are issued for the output path. If an output path starts with a
line-to or curve-to when the existing path is empty, an appropriate move-to command should be
inserted before the decoration starts.
• If a decoration uses its own path, the first time this happens the preexisting path is part of the
path that is used at this point.
Before the automata start to "work on" their respective inputs paths, hbefore codei is executed. After
the decoration automaton has finished, hafter codei is executed.
\begin{tikzpicture}[decoration={segment length=5pt}]
\draw [help lines] grid (3,2);
\begin{pgfdecoration}{{curveto}{1cm},{zigzag}{2cm},{curveto}{1cm}}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathcurveto
{\pgfpoint{0cm}{2cm}}{\pgfpoint{3cm}{2cm}}{\pgfpoint{3cm}{0cm}}
\end{pgfdecoration}
\pgfusepath{stroke}
\end{tikzpicture}
When the lengths are evaluated, the dimension \pgfdecoratedremainingdistance holds the remaining
distance on the entire decorated path, and \pgfdecoratedpathlength holds the total length of the path.
Thus, it is possible to specify lengths like \pgfdecoratedpathlength/3.
\begin{tikzpicture}[decoration={segment length=5pt}]
\draw [help lines] grid (3,2);
\begin{pgfdecoration}{
{curveto}{\pgfdecoratedpathlength/3},
{zigzag}{\pgfdecoratedpathlength/3},
{curveto}{\pgfdecoratedremainingdistance}
}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathcurveto
{\pgfpoint{0cm}{2cm}}{\pgfpoint{3cm}{2cm}}{\pgfpoint{3cm}{0cm}}
\end{pgfdecoration}
\pgfusepath{stroke}
\end{tikzpicture}
When hbefore codei is executed, the following macro is useful:
1003
\pgfpointdecoratedpathfirst
Returns the point corresponding to the start of the current input path.
When hafter codei is executed, the following macro can be used:
\pgfpointdecoratedpathlast
Returns the point corresponding to the end of the current input path.
This means that if decorations do not use their own path, it is possible to do something with them and
continue from the correct place.
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\begin{pgfdecoration}{
{curveto}{\pgfdecoratedpathlength/3}
{}
{
\pgfusepath{stroke}
},
{zigzag}{\pgfdecoratedpathlength/3}
{
\pgfpathmoveto{\pgfpointdecoratedpathfirst}
\pgfdecorationsegmentlength=5pt
}
{
\pgfsetstrokecolor{red}
\pgfusepath{stroke}
\pgfpathmoveto{\pgfpointdecoratedpathlast}
\pgfsetstrokecolor{black}
},
{curveto}{\pgfdecoratedremainingdistance}
}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathcurveto
{\pgfpoint{0cm}{2cm}}{\pgfpoint{3cm}{2cm}}{\pgfpoint{3cm}{0cm}}
\end{pgfdecoration}
\pgfusepath{stroke}
\end{tikzpicture}
After the {decoration} environment has finished, the following macros are available:
\pgfdecorateexistingpath
The preexisting path before the environment was entered.
\pgfdecoratedpath
The (total) input path (that is, the path created by the environment contents).
\pgfdecorationpath
The output path. If the path is used, this macro contains only the last unused part of the output
path.
\pgfpointdecoratedpathlast
The final point of the input path.
\pgfpointdecorationpathlast
The final point of the output path.
The following style is executed each time a decoration is used. You may use it to set up default options
for decorations.
(style, initially empty)
/pgf/every decoration
This style is executed for every decoration.
\pgfdecoration{hnamei}
henvironment contentsi
1004
\endpgfdecoration
The plain-TEX version of the {pgfdecorate} environment.
\startpgfdecoration{hnamei}
henvironment contentsi
\stoppgfdecoration
The ConTEXt version of the {pgfdecoration} environment.
For convenience, the following macros provide a “shorthand” for decorations (internally, they all use the
{pgfdecoration} environment).
\pgfdecoratepath{hnamei}{hpath commandsi}
Decorate the path described by hpath commandsi with the decoration hnamei. This is equivalent to
\pgfdecorate{{name}{\pgfdecoratedpathlength}
{\pgfdecoratebeforecode}{\pgfdecorateaftercode}}
// the path commands.
\endpgfdecorate
\pgfdecoratecurrentpath{hnamei}
Decorate the preexisting path with the decoration hnamei.
Both the above commands use the current definitions of the following macros:
\pgfdecoratebeforecode
Code executed as hbefore codei, see the description of \pgfdecorate.
\pgfdecorateaftercode
Code executed as hafter codei, see the description of \pgfdecorate.
It may sometimes be useful to add an additional transformation for each segment of a decoration. The
following command allows you to define such a “last minute transformation.”
\pgfsetdecorationsegmenttransformation{hcodei}
The hcodei will be executed at the very beginning of each segment. Note when applying multiple
decorations, this will be reset between decorations, so it needs to be specified for each segment.
\begin{tikzpicture}
\draw [help lines] grid (3,2);
\begin{pgfdecoration}{
{curveto}{\pgfdecoratedpathlength/3},
{zigzag}{\pgfdecoratedpathlength/3}
{
\pgfdecorationsegmentlength=5pt
\pgfsetdecorationsegmenttransformation{\pgftransformyshift{.5cm}}
},
{curveto}{\pgfdecoratedremainingdistance}
}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathcurveto
{\pgfpoint{0cm}{2cm}}{\pgfpoint{3cm}{2cm}}{\pgfpoint{3cm}{0cm}}
\end{pgfdecoration}
\pgfusepath{stroke}
\end{tikzpicture}
98.5
Meta-Decorations
A meta-decoration provides an alternative way to decorate a path with multiple decorations. It is, in essence,
an automaton that decorates an input path with decoration automatons. In general, however, the end effect
is still that a path is decorated with other paths, and the input path should be thought of as being divided
into sub-input-paths, each with their own decoration. Like ordinary decorations, a meta-decoration must be
declared before it can be used.
1005
98.5.1
Declaring Meta-Decorations
\pgfdeclaremetadecorate{hnamei}{hinitial statei}{hstatesi}
This command declares a new meta-decoration called hnamei. The hstatesi argument contains a description of the meta-decoration automaton’s states and the transitions between them. The hinitial
statei is the state in which the automaton starts.
The \state command is similar to the one found in decoration declarations, and takes the same form:
\state{hnamei}[hoptionsi]{hcodei}
Declares the state hnamei inside the current meta-decoration automaton. Unlike decorations, states
in meta-decorations are not executed within a group, which makes the persistent computation
options superfluous. Consider using an initial state with width=0pt to do precalculations that
could speed the execution of the meta-decoration.
The hoptionsi are executed with the key path set to /pgf/meta-decorations automaton/, and
the following keys are defined for this path:
/pgf/meta-decoration automaton/switch if less than=hdimensionitohnew statei
default)
(no
This causes pgf to check whether the remaining distance to the end of the input path is less
than hdimensioni, and, if so, to immediately switch to the state hnew statei. When this key
is evaluated, the macro \pgfmetadecoratedpathlength will be defined as the total length of
the decoration path, allowing for values such as \pgfmetadecoratedpathlength/8.
/pgf/meta-decoration automaton/width=hdimensioni
(no default)
As always, this option will cause an immediate switch to the state final if the remaining
distance on the input path is less than hdimensioni.
Otherwise, this option tells pgf the width of the “meta-segment”, that is, the length of the
sub-input-path which the decoration automaton specified in hcodei will decorate.
/pgf/meta-decoration automaton/next state=hnew statei
(no default)
After the code for a state has been executed, a state switch to hnew statei is performed. If this
option is not given, the next state is the same as the current state.
The code in hcodei is quite different from the code in a decoration state. In almost all cases only
the following three macros will be required:
\decoration{hnamei}
This sets the decoration for the current state to hnamei. If this command is omitted, the
moveto decoration will be used.
\beforedecoration{hbefore codei}
Defines hbefore codei as (typically) pgf commands to be executed before the decoration is
applied to the current segment. This command can be omitted. If you wish to set up some
decoration specific parameters such as segment length, or segment amplitude, then they can
be set in hbefore codei.
\afterdecoration{hafter codei}
Defines hafter codei as commands to be executed after the decoration has been applied to the
current segment. This command can be omitted.
There are some macros that may be useful when creating meta-decorations (note that they are all
macros):
\pgfpointmetadecoratedpathfirst
When the hbefore codei is executed, this macro stores the first point on the current sub-inputpath.
\pgfpointmetadecoratedpathlast
When the hafter codei is executed, this macro stores the last point on the current sub-inputpath.
\pgfmetadecoratedpathlength
The entire length of the entire input path.
1006
\pgfmetadecoratedcompleteddistance
The completed distance on the entire input path.
\pgfmetadecoratedremainingdistance
The remaining distance on the entire input path.
\pgfmetadecoratedinputsegmentcompleteddistance
The completed distance on the current input segment of the entire input path.
\pgfmetadecoratedinputsegmentremainingdistance
The remaining distance on the current input segment of the entire input path.
Here is a complete example of a meta-decoration:
\pgfdeclaremetadecoration{arrows}{initial}{
\state{initial}[width=0pt, next state=arrow]
{
\pgfmathdivide{100}{\pgfmetadecoratedpathlength}
\let\factor\pgfmathresult
\pgfsetlinewidth{1pt}
\pgfset{/pgf/decoration/segment length=4pt}
}
\state{arrow}[
switch if less than=\pgfmetadecorationsegmentlength to final,
width=\pgfmetadecorationsegmentlength/3,
next state=zigzag]
{
\decoration{curveto}
\beforedecoration
{
\pgfmathparse{\pgfmetadecoratedcompleteddistance*\factor}
\pgfsetcolor{red!\pgfmathresult!yellow}
\pgfpathmoveto{\pgfpointmetadecoratedpathfirst}
}
}
\state{zigzag}[width=\pgfmetadecorationsegmentlength/3, next state=end arrow]
{
\decoration{zigzag}
}
\state{end arrow}[width=\pgfmetadecorationsegmentlength/3, next state=move]
{
\decoration{curveto}
\beforedecoration{\pgfpathmoveto{\pgfpointmetadecoratedpathfirst}}
\afterdecoration
{
\pgfsetarrowsend{to}
\pgfusepath{stroke}
}
}
\state{move}[width=\pgfmetadecorationsegmentlength/2, next state=arrow]{}
\state{final}{}
}
\tikz\draw[decorate,decoration={arrows,meta-segment length=2cm}]
(0,0) .. controls (0,2)
and (3,2)
.. (3,0)
.. controls (3,-2) and (0,-2) .. (0,-4)
.. controls (0,-6) and (3,-6) .. (3,-8)
.. controls (3,-10) and (0,-10) .. (0,-8);
98.5.2
Predefined Meta-decorations
There are no predefined meta-decorations loaded with pgf.
98.5.3
Using Meta-Decorations
Using meta-decorations is “simpler” than using decorations, because you can only use one meta-decoration
per path.
\begin{pgfmetadecoration}{hnamei}
1007
henvironment contentsi
\end{pgfmetadecoration}
This environment decorates the input path described in henvironment contentsi, with the metadecoration hnamei.
\pgfmetadecoration{hnamei}
henvironment contentsi
\endpgfmetadecoration
The plain TEX version of the {pgfmetadecoration} environment.
\startpgfmetadecoration{hnamei}
henvironment contentsi
\stoppgfmetadecoration
The ConTEXt version of the {pgfmetadecoration} environment.
1008
99
Using Paths
99.1
Overview
Once a path has been constructed, it can be used in different ways. For example, you can draw the path or
fill it or use it for clipping.
Numerous graph parameters influence how a path will be rendered. For example, when you draw a path,
the line width is important as well as the dashing pattern. The options that govern how paths are rendered
can all be set with commands starting with \pgfset. All options that influence how a path is rendered
always influence the complete path. Thus, it is not possible to draw part of a path using, say, a red color
and drawing another part using a green color. To achieve such an effect, you must use two paths.
In detail, paths can be used in the following ways:
1. You can stroke (also known as draw ) a path.
2. You can add arrow tips to a path.
3. You can fill a path with a uniform color.
4. You can clip subsequent renderings against the path.
5. You can shade a path.
6. You can use the path as bounding box for the whole picture.
You can also perform any combination of the above, though it makes no sense to fill and shade a path at
the same time.
To perform (a combination of) the first four actions, you can use the following command:
\pgfusepath{hactionsi}
Applies the given hactionsi to the current path. Afterwards, the current path is (globally) empty. The
following actions are possible:
• fill fills the path. See Section 99.4 for further details.
\begin{pgfpicture}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpoint{1cm}{1cm}}
\pgfpathlineto{\pgfpoint{1cm}{0cm}}
\pgfusepath{fill}
\end{pgfpicture}
• stroke strokes the path. See Section 99.2 for further details.
\begin{pgfpicture}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpoint{1cm}{1cm}}
\pgfpathlineto{\pgfpoint{1cm}{0cm}}
\pgfusepath{stroke}
\end{pgfpicture}
• draw has the same effect as stroke.
• clip clips all subsequent drawings against the path. Always supresses arrow tips. See Section 99.5
for further details.
\begin{pgfpicture}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpoint{1cm}{1cm}}
\pgfpathlineto{\pgfpoint{1cm}{0cm}}
\pgfusepath{stroke,clip}
\pgfpathcircle{\pgfpoint{1cm}{1cm}}{0.5cm}
\pgfusepath{fill}
\end{pgfpicture}
• discard discards the path, that is, it is not used at all. Giving this option (alone) has the same
effect as giving an empty options list.
When more than one of the first three actions are given, they are applied in the above ordering, regardless
of their ordering in hactionsi. Thus, {stroke,fill} and {fill,stroke} have the same effect.
To shade a path, use the \pgfshadepath command, which is explained in Section 109.
1009
99.2
Stroking a Path
When you use \pgfusepath{stroke} to stroke a path, several graphic parameters influence how the path
is drawn. The commands for setting these parameters are explained in the following.
Note that all graphic parameters apply to the path as a whole, never only to a part of it.
All graphic parameters are local to the current {pgfscope}, but they persists past TEX groups, except
for the interior rule (even-odd or nonzero) and the arrow tip kinds. The latter graphic parameters only
persist till the end of the current TEX group, but this may change in the future, so do not count on this.
99.2.1
Graphic Parameter: Line Width
\pgfsetlinewidth{hline widthi}
This command sets the line width for subsequent strokes (in the current pgfscope). The line width is
given as a normal TEX dimension like 0.4pt or 1mm.
\begin{pgfpicture}
\pgfsetlinewidth{1mm}
\pgfpathmoveto{\pgfpoint{0mm}{0mm}}
\pgfpathlineto{\pgfpoint{2cm}{0mm}}
\pgfusepath{stroke}
\pgfsetlinewidth{2\pgflinewidth} % double in size
\pgfpathmoveto{\pgfpoint{0mm}{5mm}}
\pgfpathlineto{\pgfpoint{2cm}{5mm}}
\pgfusepath{stroke}
\end{pgfpicture}
\pgflinewidth
You can access the current line width via the TEX dimension \pgflinewidth. It will be set to the correct
line width, that is, even when a TEX group closed, the value will be correct since it is set globally, but
when a {pgfscope} closes, the value is set to the correct value it had before the scope.
99.2.2
Graphic Parameter: Caps and Joins
\pgfsetbuttcap
Sets the line cap to a butt cap. See Section 15.3.1 for an explanation of what this is.
\pgfsetroundcap
Sets the line cap to a round cap. See again Section 15.3.1.
\pgfsetrectcap
Sets the line cap to a square cap. See again Section 15.3.1.
\pgfsetroundjoin
Sets the line join to a round join. See again Section 15.3.1.
\pgfsetbeveljoin
Sets the line join to a bevel join. See again Section 15.3.1.
\pgfsetmiterjoin
Sets the line join to a miter join. See again Section 15.3.1.
\pgfsetmiterlimit{hmiter limit factor i}
Sets the miter limit to hmiter limit factor i. See again Section 15.3.1.
99.2.3
Graphic Parameter: Dashing
\pgfsetdash{hlist of even length of dimensionsi}{hphasei}
Sets the dashing of a line. The first entry in the list specifies the length of the first solid part of the list.
The second entry specifies the length of the following gap. Then comes the length of the second solid
part, following by the length of the second gap, and so on. The hphasei specifies where the first solid
part starts relative to the beginning of the line.
1010
\begin{pgfpicture}
\pgfsetdash{{0.5cm}{0.5cm}{0.1cm}{0.2cm}}{0cm}
\pgfpathmoveto{\pgfpoint{0mm}{0mm}}
\pgfpathlineto{\pgfpoint{2cm}{0mm}}
\pgfusepath{stroke}
\pgfsetdash{{0.5cm}{0.5cm}{0.1cm}{0.2cm}}{0.1cm}
\pgfpathmoveto{\pgfpoint{0mm}{1mm}}
\pgfpathlineto{\pgfpoint{2cm}{1mm}}
\pgfusepath{stroke}
\pgfsetdash{{0.5cm}{0.5cm}{0.1cm}{0.2cm}}{0.2cm}
\pgfpathmoveto{\pgfpoint{0mm}{2mm}}
\pgfpathlineto{\pgfpoint{2cm}{2mm}}
\pgfusepath{stroke}
\end{pgfpicture}
Use \pgfsetdash{}{0pt} to get a solid dashing.
99.2.4
Graphic Parameter: Stroke Color
\pgfsetstrokecolor{hcolor i}
Sets the color used for stroking lines to hcolor i, where hcolor i is a LATEX color like red or black!20!red.
Unlike the \color command, the effect of this command lasts till the end of the current {pgfscope}
and not till the end of the current TEX group.
The color used for stroking may be different from the color used for filling. However, a \color command
will always “immediately override” any special settings for the stroke and fill colors.
In plain TEX, this command will also work, but the problem of defining a color arises. After all, plain
TEX does not provide LATEX colors. For this reason, pgf implements a minimalistic “emulation” of the
\definecolor, \colorlet, and \color commands. Only gray-scale and rgb colors are supported. For
most cases this turns out to be enough.
\begin{pgfpicture}
\pgfsetlinewidth{1pt}
\color{red}
\pgfpathcircle{\pgfpoint{0cm}{0cm}}{3mm} \pgfusepath{fill,stroke}
\pgfsetstrokecolor{black}
\pgfpathcircle{\pgfpoint{1cm}{0cm}}{3mm} \pgfusepath{fill,stroke}
\color{red}
\pgfpathcircle{\pgfpoint{2cm}{0cm}}{3mm} \pgfusepath{fill,stroke}
\end{pgfpicture}
\pgfsetcolor{hcolor i}
Sets both the stroke and fill color. The difference to the normal \color command is that the effect lasts
till the end of the current {pgfscope}, not only till the end of the current TEX group.
99.2.5
Graphic Parameter: Stroke Opacity
You can set the stroke opacity using \pgfsetstrokeopacity. This command is described in Section 110.
99.2.6
Inner Lines
When a path is stroked, it is possible to request that it is stroked twice, the second time with a different
line width and a different color. This is a useful effect for creating “double” lines, for instance by setting the
line width to 2pt and stroking a black line and then setting the inner line width to 1pt and stroking a white
line on the same path as the original path. This results in what looks like two lines, each of thickness 0.5pt,
spaced 1pt apart.
You may wonder why there is direct support for this “double stroking” in the basic layer. After all, this
effect is easy to achieve “by hand”. The main reason is that arrow tips must be treated in a special manner
when such “double lines” are present. First, the order of actions is important: First, the (thick) main line
should be stroked, then the (thin) inner line, and only then should the arrow tip be drawn. Second, the way
an arrow tip looks typically depends strongly on the width of the inner line, so the arrow tip code, which is
part of the basic layer, needs access to the inner line thickness.
Two commands are used to set the inner line width and color.
1011
\pgfsetinnerlinewidth{hdimensioni}
This command sets the width of the inner line. Whenever a path is stroked (and only then), it will be
stroked normally and, afterward, it is stroked once more with the color set to the inner line color and
the line width set to hdimensioni.
In case arrow tips are added to a path, the path is first stroked normally, then the inner line is stroked,
and then the arrow tip is added. In case the main path is shortened because of the added arrow tip,
this shortened path is double stroked, not the original path (which is exactly what you want).
When the inner line width is set to 0pt, which is the default, no inner line is stroked at all (not even a
line of width 0pt). So, in order to “switch off” double stroking, set hdimensioni to 0pt.
The setting of the inner line width is local to the current TEX group and not to the current pgf scope.
Note that inner lines will not be drawn for paths that are also used for clipping. However, this may
change in the future, so you should not depend on this.
\begin{pgfpicture}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpoint{1cm}{1cm}}
\pgfpathlineto{\pgfpoint{1cm}{0cm}}
\pgfsetlinewidth{2pt}
\pgfsetinnerlinewidth{1pt}
\pgfusepath{stroke}
\end{pgfpicture}
\pgfsetinnerstrokecolor{hcolor i}
This command sets the hcolor i that is to be used when the inner line is stroked. The effect of this
command is also local to the current TEX group.
\begin{pgfpicture}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpoint{1cm}{1cm}}
\pgfpathlineto{\pgfpoint{1cm}{0cm}}
\pgfsetlinewidth{2pt}
\pgfsetinnerlinewidth{1pt}
\pgfsetinnerstrokecolor{red!50}
\pgfusepath{stroke}
\end{pgfpicture}
99.3
Arrow Tips on a Path
After a path has been drawn, pgf can add arrow tips at the ends, depending on how the tips key is set, on
whether stroke or clip arw used and on whether the path contains closed subpaths. The exact rules when
arrow tips are added are explained in Section 16.2.
\pgfsetarrowsstart{hstart arrow tip specificationi}
Sets the arrow tip kind used at the start of a (possibly curved) path. The syntax of the hstart arrow
specificationi is detailed in Section 16.4.
To “clear” the start arrow, say \pgfsetarrowsstart{}.
\begin{pgfpicture}
\pgfsetarrowsstart{Latex[length=10pt]}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpoint{1cm}{0cm}}
\pgfusepath{stroke}
\pgfsetarrowsstart{Computer Modern Rightarrow}
\pgfpathmoveto{\pgfpoint{0cm}{2mm}}
\pgfpathlineto{\pgfpoint{1cm}{2mm}}
\pgfusepath{stroke}
\end{pgfpicture}
The effect of this command persists only till the end of the current TEX scope.
\pgfsetarrowsend{hend arrow tip specificationi}
Sets the arrow tip kind used at the end of a path.
1012
\begin{pgfpicture}
\pgfsetarrowsstart{Latex[length=10pt]}
\pgfsetarrowsend{Computer Modern Rightarrow}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpoint{1cm}{0cm}}
\pgfusepath{stroke}
\end{pgfpicture}
\pgfsetarrows{hargumenti}
The hargumenti can be of the form hstart arrow tip specifciationi-hend arrow tip specificationi. In this
case, both the start and the end arrow specification are set:
\begin{pgfpicture}
\pgfsetarrows{Latex[length=10pt]-»}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathlineto{\pgfpoint{1cm}{0cm}}
\pgfusepath{stroke}
\end{pgfpicture}
Alternatively, hargumenti can be of the form [harrow keysi]. In this case, the harrow keysi will be set
for all arrow tips in the current scope, see Section 16.4.5.
\pgfsetshortenstart{hdimensioni}
This command will shortened the start of every stroked path by the given dimension. This shortening
is done in addition to automatic shortening done by a start arrow, but it can be used even if no start
arrow is given.
It is usually better to use the sep key with arrow tips.
This command is useful if you wish arrows or lines to “stop shortly before” a given point.
\begin{pgfpicture}
\pgfpathcircle{\pgfpointorigin}{5mm}
\pgfusepath{stroke}
\pgfsetarrows{Latex-}
\pgfsetshortenstart{4pt}
\pgfpathmoveto{\pgfpoint{5mm}{0cm}} % would be on the circle
\pgfpathlineto{\pgfpoint{2cm}{0cm}}
\pgfusepath{stroke}
\end{pgfpicture}
\pgfsetshortenend{hdimensioni}
Works like \pgfsetshortenstart.
99.4
Filling a Path
Filling a path means coloring every interior point of the path with the current fill color. It is not always
obvious whether a point is “inside” a path when the path is self-intersecting and/or consists or multiple parts.
In this case either the nonzero winding number rule or the even-odd crossing number rule is used to decide
which points lie “inside.” These rules are explained in Section 15.5.
99.4.1
Graphic Parameter: Interior Rule
You can set which rule is used using the following commands:
\pgfseteorule
Dictates that the even-odd rule is used in subsequent fillings in the current TEX scope. Thus, for once,
the effect of this command does not persist past the current TEX scope.
\begin{pgfpicture}
\pgfseteorule
\pgfpathcircle{\pgfpoint{0mm}{0cm}}{7mm}
\pgfpathcircle{\pgfpoint{5mm}{0cm}}{7mm}
\pgfusepath{fill}
\end{pgfpicture}
1013
\pgfsetnonzerorule
Dictates that the nonzero winding number rule is used in subsequent fillings in the current TEX scope.
This is the default.
\begin{pgfpicture}
\pgfsetnonzerorule
\pgfpathcircle{\pgfpoint{0mm}{0cm}}{7mm}
\pgfpathcircle{\pgfpoint{5mm}{0cm}}{7mm}
\pgfusepath{fill}
\end{pgfpicture}
99.4.2
Graphic Parameter: Filling Color
\pgfsetfillcolor{hcolor i}
Sets the color used for filling paths to hcolor i. Like the stroke color, the effect lasts only till the next
use of \color.
99.4.3
Graphic Parameter: Fill Opacity
You can set the fill opacity using \pgfsetfillopacity. This command is described in Section 110.
99.5
Clipping a Path
When you add the clip option, the current path is used for clipping subsequent drawings. The same rule
as for filling is used to decide whether a point is inside or outside the path, that is, either the even-odd rule
or the nonzero rule.
Clipping never enlarges the clipping area. Thus, when you clip against a certain path and then clip again
against another path, you clip against the intersection of both.
The only way to enlarge the clipping path is to end the {pgfscope} in which the clipping was done. At
the end of a {pgfscope} the clipping path that was in force at the beginning of the scope is reinstalled.
99.6
Using a Path as a Bounding Box
When you add the use as bounding box option, the bounding box of the picture will be enlarged
such that the path in encompassed, but any subsequent paths of the current TEX scope will not have
any effect on the size of the bounding box. Typically, you use this command at the very beginning of a {pgfpicture} environment. Alternatively, you can use \pgfresetboundingbox, followed by
\pgfusepath{use as bounding box} to overrule the picture’s bounding box completely.
Left right.
Left
\begin{pgfpicture}
\pgfpathrectangle{\pgfpointorigin}{\pgfpoint{2ex}{1ex}}
\pgfusepath{use as bounding box} % draws nothing
\pgfpathcircle{\pgfpointorigin}{2ex}
\pgfusepath{stroke}
\end{pgfpicture}
right.
1014
100
100.1
Defining New Arrow Tip Kinds
Overview
In present section we have a look at how you can define new arrow tips for use in pgf. The low-level
commands for selecting which arrow tips are to be used have already been described in Section 99.3, the
general syntax rules for using arrows are detailed in Section 16. Although Section 16 describes the use of
arrows in Tik Z, in reality, Tik Z itself does not actually do anything about arrow tips; all of the functionality
is implemented on the pgf level in the commands described in Section 16. Indeed, even the /.tip key
handler described in Section 16 is actually implemented on the pgf layer.
What has not yet been covered is how you can actually define a complete new arrow tip. In pgf, arrows
are “meta-arrows” in the same way that fonts in TEX are “meta-fonts.” When a meta-arrow is resized, it is
not simply scaled, but a possibly complicated transformation is applied to the size.
A meta-font is not one particular font at a specific size with a specific stroke width (and with a large
number of other parameters being fixed). Rather, it is a “blueprint” (actually, more like a program) for
generating such a font at a particular size and width. This allows the designer of a meta-font to make sure
that, say, the font is somewhat thicker and wider at very small sizes. To appreciate the difference: Compare
the following texts: “Berlin” and “Berlin”. The first is a “normal” text, the second is the tiny version scaled
by a factor of two. Obviously, the first look better. Now, compare “ Berlin” and “Berlin”. This time, the normal
text was scaled down, while the second text is a “normal” tiny text. The second text is easier to read.
pgf’s meta-arrows work in a similar fashion: The shape of an arrow tip can vary according to a great
number of parameters, the line width of the arrow tip being one of them. Thus, an arrow tip drawn at a
line width of 5pt will typically not be five times as large as an arrow tip of line width 1pt. Instead, the size
of the arrow will get bigger only slowly as the line width increases.
To appreciate the difference, here are the Latex and Classical TikZ Rightarrow arrows, as drawn by
pgf at four different sizes:
line width is 0.1pt
line width is 0.1pt
line width is 0.4pt
line width is 0.4pt
line width is 1.2pt
line width is 1.2pt
line width is 5pt
line width is 5pt
Here, by comparison, are the same arrows when they are simply “resized”:
line width is 0.1pt
line width is 0.1pt
line width is 0.4pt
line width is 0.4pt
line width is 1.2pt
line width is 1.2pt
line width is 5pt
line width is 5pt
As can be seen, simple scaling produces arrow tips that are way too large at larger sizes and way too
small at smaller sizes.
In addition to the line width, other options may also influence the appearance of an arrow tip. In
particular, the width of the inner line (the line used to create the effect of a double line) influences arrow
tips as well as other options that are specific to the arrow tip.
100.2
Terminology
Before we have a look at the exact commands used for defining arrow tips, we need to fix some terminology.
Consider the following drawing of an arrow tip where the arrow tip is drawn transparently so that we can
see what is “happening behind it”:
1015
y-axis
2
1
−3
−2
−1
1
2
x-axis
−1
−2
I have also added a coordinate system. The code for drawing an arrow tip always draws it in the way
shown above: Pointing right along the x-axis.
We will use the following terminology:
• The point where tip of the arrow ends is called the tip end. It is at (1, 0) in our example and we always
assume it to lie on the x-axis, so we just treat it as a distance, 1 in this case. This is the position
where the original path was supposed to end (so if the arrow tip had not been added to the red path,
it would have ended here).
• The back end of the arrow is where a vertical line just to the left of the arrow intersects the x-axis. In
our case, this is the point (−3, 0) and again we treat it as a distance, −3 in this case.
• The line end is the position where the path now ends. This should be a position inside the arrow head
that gets “covered” by the path. Note that a path may have a round or a rect head and should still be
covered. Clearly, necessary shortening of the path will be the difference between the tip end and the
line end.
• The visual back end is the position where the path and the the arrow head “meet last” on the path. In
our case, because of the inset, the visual back end is not the same as the back end: The arrow ends
“visually” at (−2, 0). The difference between the back end and the visual back end is important when
the arrow tip is flexed, see Section 16.3.8 for an explanation of flexing.
• There is also a visual tip end, the counterpart of the visual back end for the front. In our case, the
visual tip end and the tip end obviously coincide, but if we were to reverse the arrow tip, the visual
tip end would be different form the tip end (while the visual back end would then coincide with the
new back end).
• There are four points that make up the convex hull of the arrow tip: (1, 0), (−3, 2), and (−3, −2).
Normally, pgf automatically keeps track of a bounding box of everything you draw. However, since
arrow tips are drawn so often, pgf caches the code needing for drawing arrow tips internally and because
of this cache it cannot determine the size of the arrow tip just based on the drawing commands used for
drawing the tip. Instead, a convex hull of the arrow tip must be explicitly provided in the definition.
When you design a new arrow tip, all of the above parameters must be defined.
100.3
Caching and Rendering of Arrows
As a last preparation for the description of the commands for declaring arrows, it is important to understand
the exact process by which pgf draws arrows.
1. First, you have to define an arrow tip kind using \pgfdeclarearrow{name=foo,.... This will tell
pgf that foo is now the name of an arrow tip. In particular, the parser for arrow tip specifications
will now treat foo as the name of an arrow tip and will not try to consider f, o, and o as the names
of single-char shorthands.
Other than storing the definitions in the declaration internally, this command has little other effect.
In particular, no drawing or other processing takes place.
1016
2. Now assume that at some point the arrow tip foo is actually used. In this case, certain options may
have been set, for instance the user may have requested the arrow tip foo[length=5pt,open]. What
happens next depends on whether it is the first time the arrow tip foo is used with these exact options
ornot.
3. Assume that is the first time foo is requested at a length of 5pt and in an “open” version. pgf now
retrieves the definition of the arrow tip kind that it stored in the first step and executes the so-called
setup code. When this code is executed, all the options will be in force (for instance, \pgfarrowlength
will equal 5pt in our case). The job of the setup code is two-fold: First, it needs to compute all of the
parameters listed in Section 100.2, that is, it has to compute where the tip end will lie in the arrow
tip’s coordinate system at the particular size of 5pt, where the back end will be, where the convex hull
points lie, and so on. Second, the setup code should precompute values that will be important for
constructing the path of the arrow. In our example, there is little to do in this regard, but for more
complicated arrows, all time-consuming preparations are done now.
It is not the job of the setup to actually draw the arrow tip, only to “prepare” this as much as possible.
The setup code will always be executed only once for each arrow tip kind for a given set of options.
Thus, when a user uses foo[length=5pt,open] once more later anywhere in the document, the setup
code will not be executed again.
4. The next thing that happens is that we have a look at the drawin code stored in the code field of
the arrow. In our example, the drawing code would consist of creating a filled path with four straight
segments.
In most cases, what happens now is that the drawing code is executed in a special sandbox in
which the low-level driver commands that do the actual drawing are intercepted and stored away
in a so-called cache. Once such a cache has been created, its contents will be reused whenever
foo[length=5pt,open] is requested by a user and just like the setup code, the drawing code will
not be executed again.
There are, however, two cases in which the drawing code gets executed each time the arrow is used:
First, an arrow tip kind can specify that this should always happen by saying cachable=false in its
definition. This is necessary if the drawing code contains low-level drawing commands that cannot be
intercepted such as a use of \pgftext for arrow tips that “contain text.” Second, when the bend option
is used, the same arrow tip will look different each time it is used, namely in dependence on the exact
curvature of the path to which it is added.
Because the drawing code may be executed several times, while the setup code may not, we must find
a way to “communicate” the values computed by the setup code to the drawing code. This is done by
explicitly calling \pgfarrowssave inside the setup code. Whatever is “saved” in this way is restored
each time before the drawing code is executed.
As can be seen, the process is a bit involved, but it leads to a reasonably fast arrow tip management.
100.4
Declaring an Arrow Tip Kind
\pgfdeclarearrow{hconfigi}
This command is both used to define a new arrow tip kind and to to declare a so-called shorthand. We
have a look at the case that a complete new arrow tip kind is created and then have a look how the
command can be used to create shorthands.
Defining a Complete New Arrow Tip Kind. The hconfigi is a key–value list in which different
keys are used to setup the to-be defined arrow. The following keys can be given:
• name=hnamei or name=hstart namei-hend namei
This defines the name of the arrow tip. It is legal to define an arrow tip a second time, in this case
the previous definition will be overwritten in the current TEX scope. It is customary to use a name
with an uppercase fist letter for a “complete” arrow tip kind. Short names and lower case names
should be used for shorthands that change their meaning inside a document, while arrow tips with
uppercase first letters should not be redefined.
If the name contains a hyphen, the second syntax is assumed and everything before the hyphen
will be the name used in start arrow specifications, while the text after the hyphen is the name
used in end specifications.
1017
• parameters={hlist of macrosi}
As explained earlier, an arrow tip typically needs to be redrawn each time an option like length
or inset is changed. However, for some arrow tips, the inset has no influence, while for other
it is important whether the arrow is reversed or not. (How keys like length actually set TEX
dimensions like \pgfarrowlength is explained in Section 100.5.)
The job of the parameters key is to specify which dependencies the arrow tip has. Everything
that will influence any of the parameters computed in the setup code or used in the drawing code
should be listed here.
The hlist of macrosi will be used inside a \csname-\endcsname pair and should expand to the
current values of the relevant parameters have. For example, if the arrow tip depends on the
current value of \pgfarrowlength and \pgfarrowwidth only, then hlist of macrosi should be set
to \the\pgfarrowlength,\the\pgfarrowwidth. (Actually, the comma is optional, the hlist of
macrosi does not really have to be a list, just something that can be expanded unambiuously.)
Note that the line width (\pgflinewidth) and the inner line width (\pgfinnerlinewidth) are
always parameters and need not be specified in the parameters.
It is important to get this parameter right. Otherwise, arrow tips may look wrong because pgf
thinks that it can reuse some code when, in reality, this code actually depends on a parameter not
listed here.
• setup code={hcodei}
When an arrow tip is used, the value stored in parameters is expanded and it is tested whether
the result was encountered before. If not, the hcodei gets executed (only this once). The code can
now do aribtrarily complicated computations the prepare the later drawing of the arrow tip. Also
the hcodei must specify the different tip and back ends and the convex hull points. This is done
by calling the following macros inside the hcodei:
\pgfarrowssettipend{hdimensioni}
When this command is called inside the setup code of an arrow tip, it specifies that the tip of
the drawn arrow will end exactly at hdimensioni. For example, for our earlier example of the
large arrow tip, where the tip end was at 1cm, we would call
\pgfarrowssettipend{1cm}
Note that for efficience reasons, the hdimensioni is not passed through \pgfmathsetlength;
rather what happens is that \pgf@x=hdimensioni gets executed. In particular, you can pack
further computations into the hdimensioni by simply starting it with a number and then
appending some code that modifies \pgf@x. Here is an example where instead of 1cm we use
1cm − 12 linewidth as the tip end:
\pgfarrowssettipend{1cm\advance\pgf@x by-.5\pgflinewidth}
If the command is not called at all inside the setup code, the tip end is set to 0pt.
\pgfarrowssetbackend{hdimensioni}
Works like the command for the tip end, only it sets the back end. In our example we would
call
\pgfarrowssettipend{-3cm}
Defaults to 0pt.
\pgfarrowssetlineend{hdimensioni}
Sets the line end, so in the example we have \pgfarrowssettipend{-1cm}. Default to 0pt.
\pgfarrowssetvisualbackend{hdimensioni}
Sets the visual back end, \pgfarrowssetvisualbackend{-2cm} in our example. Default to
the value of the normal back end.
\pgfarrowssetvisualtipend{hdimensioni}
Sets the visual tip end. Default to the value of the normal tip end and, thus, we need not set
it in our example.
1018
\pgfarrowshullpoint{hx dimensioni}{hy dimensioni}
Adds a point to the convex hull of the arrow tip. As for the previous commands, no math
parsing is done; instead pgf says \pgf@x=hx dimensioni and then \pgf@y=hy dimensioni.
Thus, both “dimensions” can contain code for advancing and thus modifying \pgf@x and
\pgf@y.
In our example we would write
\pgfarrowshullpoint{1cm}{0pt}
\pgfarrowshullpoint{-3cm}{2cm}
\pgfarrowshullpoint{-3cm}{-2cm}
\pgfarrowsupperhullpoint{hx dimensioni}{hy dimensioni}
This command works like the previous command, only it normally adds two points to
the convex hull: First, the point (hx dimensioni, hy dimensioni) and, secondly, the point
(hx dimensioni, −hy dimensioni). However, the second point is only added if the arrow is
not a harpoon.
Thus, in our example we could simplify the convex hull to
\pgfarrowshullpoint{1cm}{0pt}
\pgfarrowsupperhullpoint{-3cm}{2cm}
If the hy dimensioni is zero or less, only one point, namely (hx dimensioni, hy dimensioni), is
added to the hull. Thus, we could also have used the upper convex hull command in the first
of the two of the above commands.
\pgfarrowssave{hmacroi}
As explained earlier, the setup code needs to “communicate” with the drawing code via “saved
values.” This command get the name of a macro and will store the value this macro had
internally. Then, each time drawing code is executed, the value of this macro will be restored.
\pgfarrowssavethe{hregister i}
Works like \pgfarrowssave, only the parameter must be a register and \thehregister i will be
saved. Typically, you will write something like
\pgfarrowssavethe{\pgfarrowlength}
\pgfarrowssavethe{\pgfarrowwidth}
To ensure that inside the drawing code the the dimension registers \pgfarrowlength and
\pgfarrowwidth are setup with the values they had during the setup.
• drawing code={hcodei}
This code will be executed at least once for each setting of the parameters when the time arrow
tip is actually drawn. Usually, this one execution will be all and the low-level commands generated
inside the hcodei will we stored in a special cache; but in some cases the hcodei gets executed each
time the arrow tip is used, so do not assume anything about it. Inside the hcodei, you have access
to all values that were saved in the setup code as well as to the line width.
The hcodei should draw the arrow tip “going right along the x-axis.” pgf will take care of setting
up a canvas transformation beforehand to a rotation such that when the drawing is rendered, the
arrow tip that is actually drawn points in the direction of the line. Alternatively, when bending is
switched on, even more complicated low-level transformations will be done automatically.
The are some special considerations concerning the hcodei:
– In the hcodei you may not use \pgfusepath since this would try to add arrow tips to the arrow
tip and lead to a recursion. Use the “quick” versions \pgfusepathqstroke and so on instead,
which never try to add arrow tips.
– If you stroke the path that you construct, you should first set the dashing to solid and set up
fixed joins and caps, as needed. This will ensure that the arrow tip will always look the same.
– When the arrow tip code is executed, it is automatically put inside a low-level scope, so nothing
will “leak out” from the scope.
– The high-level coordinate transformation matrix will be set to the identity matrix when the
code is executed for the first time.
1019
• cache=htrue or falsei
When set to true, which is the default, the hcodei will be executed only once for a partiular
value of parameters and the low-level commands created by the drawing code (using the system
layer protocol subsystem, see Section 116) will be cached and reused later on. However, when the
drawing code contains “uncachable” code like a call to \pgftext, caching must be switched off by
saying cache=false.
• bending mode=hmodei
This key is important only when the bend option is used with an arrow, see Section 16.3.8 for an
introduction to this option. The bend option asks us to, well, bend the arrow head. For some
arrow head this is not possible or leads to very strange drawings (for instance, when the \pgftext
command is used) and then it is better to switch bending off for the arrow head (flex will then
be used instead). To achieve this, set hmodei to none.
For most arrow tips it does, however, make sense to bend them. There are (at least) two different
mathematical ways of doing so, see Section 103.4.7 for details. Which of these ways is use can be
configured by setting hmodei to either orthogonal or to polar. It is best to try simply try out
both when designing an arrow tip to see which works better. Since orthogonal is quicker and
often gives good oder even better results, it is the default. Some arrow tips, however, profit from
saying bending mode=polar.
• defaults=harrow keysi
The harrow keysi allow you to configure the default values for the parameters on which an arrow tip
depends. The harrow keysi will be executed first before any other arrow tip options are executed,
see Section 16.4.5 for the exact sequence. Also see Section 100.5 below for more details on arrow
options.
This concludes the description of the keys you provide for the declaration of an arrow. Let us now
have a look at a simple example that uses these features: We want to define an arrow tip kind foo that
produces the arrow tip we used as our running examlpe. However, to make things a bit more interesting,
let us make it “configurable” insofar as the length of the arrow tip can be configured using the length
option, which sets the \pgfarrowlength. By default, this length should be the gigantic 4cm we say in
the example, but uses should be able to set it to anything they like. We will not worry about the arrow
width or insets, of arrow line width, or harpoons, or anything else in this example to keep it simple.
Here is the code:
\pgfdeclarearrow{
name = foo,
parameters = { \the\pgfarrowlength },
setup code = {
% The different end values:
\pgfarrowssettipend{.25\pgfarrowlength}
\pgfarrowssetlineend{-.25\pgfarrowlength}
\pgfarrowssetvisualbackend{-.5\pgfarrowlength}
\pgfarrowssetbackend{-.75\pgfarrowlength}
% The hull
\pgfarrowshullpoint{.25\pgfarrowlength}{0pt}
\pgfarrowshullpoint{-.75\pgfarrowlength}{.5\pgfarrowlength}
\pgfarrowshullpoint{-.75\pgfarrowlength}{-.5\pgfarrowlength}
% Saves: Only the length:
\pgfarrowssavethe\pgfarrowlength
},
drawing code = {
\pgfpathmoveto{.25\pgfarrowlength}{0pt}
\pgfpathlineto{-.75\pgfarrowlength}{.5\pgfarrowlength}
\pgfpathlineto{-.5\pgfarrowlength}{0pt}
\pgfpathlineto{-.75\pgfarrowlength}{-.5\pgfarrowlength}
\pgfpathclose
\pgfusepathqfill
},
defaults = { length = 4cm }
}
We can now use it:
1020
\tikz \draw [-foo] (0,0) -- (8,0);
\tikz \draw [-{foo[length=2cm,bend]}] (0,0) to [bend left] (3,0);
Defining a Shorthand. The \pgfdeclarearrow command can also used to define shorthands. This
works as follows:
• First, you must provide a name just in the same way as when you define a full-flung new arrow tip
kind.
• Second, instead of all of the other options listed above, you just use one more option:
means=hend arrow specificationi
This sets up things so that whenever hnamei is now used in an arrow specification, it will be
replaced by the hend arrow specificationi (the problems resulting form the hnamei begin used in
a start arrow specification are taken care of automatically). See also Section 16.4.4 for details on
the order in which options get executed in such cases.
Note that the hend arrow specificationi will be executed immediately to build the so-called arrow
option caches, a concept explored in more detail in Section 100.5.4. In practice, this has mainly
two effects: First, all arrow tips referred to in the specification must already exist (at least as
“dummy” versions). Second, all dimensions mentioned in options of the hend arrow specificationi
will be evaluated immediately. For instance, when you write
\pgfdeclarearrow{ name=foo, means = bar[length=2cm+\mydimen] }
The value 2cm+\mydimen is evaluated immediately. When foo is used later on and \mydimen has
changed, this has no effect.
100.5
Handling Arrow Options
When you declare an arrow tip, your drawing code should take into account the different arrow keys set for
it (like the arrow tip length, width, or harpooning). The different arrow keys that are available have been
described in detail in Section 16.3; but how do we access the values set by an option like length or harpoon
or bend in the drawing code? In the present section we have a look at how this works.
100.5.1
Dimension Options
Most arrow keys, like length or width’, simple set a TEX dimension register to a certain value. For example,
length sets the value of the TEX dimension register \pgfarrowlength. Note that length takes several values
as input with a complicated semantics as explained for the length key on page 185. All of these settings
are not important for the setup code: When it gets executed, the code behind the length key will have
computed a simple number that is stored in \pgfarrowlength. Indeed, inside the setup code you do not
have access to the exact value given to the length key; just to the final computed value.
The following TEX dimensions are available to the setup code:
• \pgfarrowslength. It gets set by the arrow keys length and angle.
1021
• \pgfarrowswidth. It gets set by width, width’, and angle.
• \pgfarrowsinset. It gets set by inset and inset’.
• \pgfarrowslinewidth. It gets set by line width and line width’.
If your setup code depends on any of them, add them to the parameters key of the arrow tip.
100.5.2
True–False Options
A number of arrow keys just do a yes/no switch, like reversed. All of them setup a TEX-if that you can
access in the setup code:
• \ifpgfarrowreversed is setup by reversed.
• \ifpgfarrowswap is setup by swap and also right.
• \ifpgfarrowharpoon is setup by harpoon and also left and right.
• \ifpgfarrowroundcap is set to true by line cap=round and set to false by line cap=butt. It also
gets (re)set by round and sharp.
• \ifpgfarrowroundjoin is set to true by line join=round and set to false by line join=miter. It
also gets (re)set by round and sharp.
• \ifpgfarrowopen is set to true by fill=none and by open (which is a shorthand for fill=none) and
set to false by color and all other fill=hcolor i.
If you code depends on any of these, you must add them to the parameters in such a way that the
parameters are different when the TEX-if is set from when it is not set. An easy way to achieve this is to
write something like
parameters = { \the\pgfarrowlength,...,
\ifpgfarrowharpoon h\fi\
\ifpgfarrowroundjoin j\fi}
In other words, for each set parameter on which the arrow tip depends, a specific letter is added to the
parameters, making them unique.
The first two of the above keys are a bit special: Reversing and swapping an arrow tip can be done just
by fiddling with the transformation matrix: a reverse is a “flip” along the y-axis and a swap is a flip along
the x-axis. This is done automatically by pgf.
Nevertheless, you may wish to modify you code in dependence especially of the reverse key: When
\ifpgfarrowreverse is true, pgf will flip the coordinate system along the y-axis, will negate all end values
(like line end, tip end, and so on) and will exchange the meaning of back end and tip end as well as of visual
back end and visual back end. Usually, this is exactly what one need; except that the line end may no longer
be appropriate. After all, the line end should be chosen so that it is completely covered by the arrow. Now,
when the arrow tip is open, a reversed arrow should no longer have the line end near the old visual back
end, but near to the old visual tip end.
For these reasons, you may need to make the computation of the line end dependent on whether the
arrow is reversed or not. Note that when you specify a different line end for a reversed arrow tip, the
transformation and inverting of the coordinate system will still be done, meaning that if reverse is true,
you need to specify a line end in the “old” coordinate system that is at the position where, after everything
is inverted, it will be at the correct position. Usually that means that if the reverse option is set, you need
to increase the line end.
100.5.3
Inaccessible Options
There are some options that influence the way an arrow tip looks, but that you cannot access inside the
setup code. Handling these options lies entirely with pgf. If you wish your setup code to handle these
options, you have to setup your own “parallel” options.
• quick, flex, flex’, and bend are all handled automatically. You can, however, set the bending mode
to avoid bending of your arrow tip.
1022
• The colors set by color and fill. You can, however, access them indirectly, namely through the
current stroke and fill colors.
• sep
100.5.4
Defining New Arrow Keys
The set of predefined options is already quite long and most arrow tips will not need more than the predefined
options. However, sometimes an arrow tip may need to introduce a new special-purpose option. For instance,
suppose we wish to introcue a new fictive arrow key depth. In such cases, you must do two things:
1. Introduce a new dimension register or macro that will hold the configuration value and which will be
accessed by the setup code. The could be achieved by saying
\newdimen\pgfarrowdepth
2. Introduce a new arrow key option /pgf/arrow keys/depth that allows users to configure the new
macro or register.
When an arrow is selected via for instance foo[depth=5pt], the key–value pairs between the square
brackets are executed with the path prefix /pgf/arrow keys. Thus, in the example, our depth key would
get executed. Thus, it is temping to write something like
\pgfkeys{/pgf/arrow keys/depth/.code = \pgfmathsetlength{\pgfarrowdepth}{#1}}
Sadly, this will not work. The reason is that the is yet another level of caching involved when pgf
processes arrow tips: The option cache! The problem is each time an arrow tip is used, even when the
drawing code of the arrow tip is nicely cached, we still need to process the options in foo[length=5pt]
to find out which version in the cache we would like to access. To make matters worse, foo might be a
shorthand that calls other arrow tips, which add more options, and so on. Unfortunately, executing keys
is quite an expensive operation (pgf’s key–value parser is powerful, but that power comes at a price). So,
whenever possible, we do not want the key–value parser to be started.
For these reasons, when something like foo[hoptionsi] is encountered inside a shorthand, the hoptionsi
are executed only once. They should now setup the arrow option cache, which is some code that, when
executed, should setup the values that the hoptionsi configure. In our example, the depth key should add
something to the arrow option cache that sets \pgfarrowdepth to the given value.
Adding something to the arrow option cache is done using the following command:
\pgfarrowsaddtooptions{hcodei}
This command should be called by keys with the prefix /pgf/arrow keys to add code to the arrow
option cache. For our depth key example, we could use this key as follows:
\pgfkeys{/pgf/arrow keys/depth/.code=
\pgfarrowsaddtooptions{\pgfmathsetlength{\pgfarrowdepth}{#1}}
Actually, this is still not optimal since the expensive \pgfmathsetlength command is now called each
time an arrow tip is used with the depth option set. The trick is to do the expensive operation only
once and then store only very quick code in the arrow option cache:
\pgfkeys{/pgf/arrow keys/depth/.code=
\pgfmathsetlength{\somedimen}{#1}
\pgfarrowsaddtooptions{\pgfarrowdepth=\somedimen} % buggy
The above code will not (yet) work since \somedimen will surely have a different value when the cache
is executed. The trick is to use some \expandafters:
\pgfkeys{/pgf/arrow keys/depth/.code=
\pgfmathsetlength{\somedimen}{#1}
\expandafter\pgfarrowsaddtooptions\expandafter{\expandafter\pgfarrowdepth\expandafter=\the\somedimen}
1023
\pgfarrowsaddtolateoptions{hcodei}
This command works like \pgfarrowsaddtooptions, only the hcodei will be executed “later” than the
code added by the normal version of the command. This is useful for keys that depend on the length of
an arrow: Keys like width’ want to define the arrow width as a multiple of the arrow length, but when
the width’ key is given, the length may not yet have been specified. By making the computation of the
width a “late” option, we ensure that \pgfarrowlength will have been setup correctly.
If you define a new option that sets a dimensions and if that dimension should change in accordance
to the setting of either scale length or scale width, you need to make pgf “aware” of this using the
following key:
\pgfarrowsaddtolengthscalelist{hdimension register i}
Each time an arrow tip is used, the given hdimension register i will be multiplied by the scale length
factor prior to the actual drawing. You call this command only once in the preamble somewhere.
\pgfarrowsaddtowidthscalelist{hdimension register i}
Works like \pgfarrowsaddtolengthscalelist, only for width parameters.
\pgfarrowsthreeparameters{hline-width dependent size specificationi}
This command is useful for parsing the values given to keys like length or width the expect a dimension followed optionally for some numbers. This command converts the hline-width dependent size
specificationi, which may consist of one, two, or three numbers, into a triple of three numbers in curly
braces, which gets stored in the macro \pgfarrowstheparameters. Here is an example, where \showvalueofmacro is used in this example to show the value stored in a macro:
{2.0pt}{1}{0}
\pgfarrowsthreeparameters{2pt 1}
\showvalueofmacro\pgfarrowstheparameters
\pgfarrowslinewidthdependent{hdimensioni}{hline width factor i}{houter factor i}
This command take three parameters and does the “line width dependent computation” described on
page 185 for the length key. The result is returned in \pgf@x.
The idea is that you can setup line-width dependent keys like length or width using code like the
following:
\pgfkeys{/pgf/arrow keys/depth/.code={%
\pgfarrowsthreeparameters{#1}%
\expandafter\pgfarrowsaddtolateoptions\expandafter{%
\expandafter\pgfarrowslinewidthdependent\pgfarrowstheparameters% compute...
\pgfarrowdepth\pgf@x% ... and store.
}%
}
\pgfarrowslengthdependent{hdimensioni}{hlength factor i}{hdummyi}
This command take three parameters, of which the last one is ignored, and does the “length dependent
computation” described for the width’ and inset’ keys. The result is returned in \pgf@x.
You can setup length dependent keys using code like the following:
\pgfkeys{/pgf/arrow keys/depth’/.code={%
\pgfarrowsthreeparameters{#1}%
\expandafter\pgfarrowsaddtolateoptions\expandafter{%
\expandafter\pgfarrowslengthdependent\pgfarrowstheparameters% compute...
\pgfarrowdepth\pgf@x% ... and store.
}%
}
1024
101
Nodes and Shapes
This section describes the shapes module.
\usepgfmodule{shapes} % LATEX and plain TEX and pure pgf
\usepgfmodule[shapes] % ConTEXt and pure pgf
This module defines commands both for creating nodes and for creating shapes. The package is loaded
automatically by pgf, but you can load it manually if you have only included pgfcore.
101.1
Overview
pgf comes with a sophisticated set of commands for creating nodes and shapes. A node is a graphical
object that consists (typically) of (one or more) text labels and some additional stroked or filled paths. Each
node has a certain shape, which may be something simple like a rectangle or a circle, but it may also
be something complicated like a uml class diagram (this shape is currently not implemented, though).
Different nodes that have the same shape may look quite different, however, since shapes (need not) specify
whether the shape path is stroked or filled.
101.1.1
Creating and Referencing Nodes
You create a node by calling the macro \pgfnode or the more general \pgfmultipartnode. This macro
takes several parameters and draws the requested shape at a certain position. In addition, it will “remember”
the node’s position within the current {pgfpicture}. You can then, later on, refer to the node’s position.
Coordinate transformations are “fully supported,” which means that if you used coordinate transformations
to shift or rotate the shape of a node, the node’s position will still be correctly determined by pgf. This is
not the case if you use canvas transformations instead.
101.1.2
Anchors
An important property of a node or a shape in general are its anchors. Anchors are “important” positions in
a shape. For example, the center anchor lies at the center of a shape, the north anchor is usually “at the
top, in the middle” of a shape, the text anchor is the lower left corner of the shape’s text label (if present),
and so on.
Anchors are important both when you create a node and when you reference it. When you create a node,
you specify the node’s “position” by asking pgf to place the shape in such a way that a certain anchor lies
at a certain point. For example, you might ask that the node is placed such that the north anchor is at the
origin. This will effectively cause the node to be placed below the origin.
When you reference a node, you always reference an anchor of the node. For example, when you request
the “north anchor of the node just placed” you will get the origin. However, you can also request the
“south anchor of this node,” which will give you a point somewhere below the origin. When a coordinate
transformation was in force at the time of creation of a node, all anchors are also transformed accordingly.
101.1.3
Layers of a Shape
The simplest shape, the coordinate, has just one anchor, namely the center, and a label (which is usually
empty). More complicated shapes like the rectangle shape also have a background path. This is a pgf-path
that is defined by the shape. The shape does not prescribe what should happen with the path: When a node
is created, this path may be stroked (resulting in a frame around the label), filled (resulting in a background
color for the text), or just discarded.
Although most shapes consist just of a background path plus some label text, when a shape is drawn,
up to seven different layers are drawn:
1. The “behind the background layer.” Unlike the background path, which can be used in different ways
by different nodes, the graphic commands given for this layer will always stroke or always fill the path
they construct. They might also insert some text that is “behind everything.”
2. The background path layer. How this path is used depends on the arguments of the \pgfnode command.
1025
3. The “before the background path layer.” This layer works like the first one, only the commands of this
layer are executed after the background path has been used (in whatever way the creator of the node
chose).
4. The label layer. This layer inserts the node’s text box(es).
5. The “behind the foreground layer.” This layer, like the first layer, once more contains graphic commands
that are “simply executed.”
6. The foreground path layer. This path is treated in the same way as the background path, only it is
drawn after the label text has been drawn.
7. The “before the foreground layer.”
Which of these layers are actually used depends on the shape.
101.1.4
Node Parts
A shape typically does not consist only of different background and foreground paths, but it may also have
text labels. Indeed, for many shapes the text labels are the more important part of the shape.
Most shapes will have only one text label. In this case, this text label is simply passed as a parameter to
the \pgfnode command. When the node is drawn, the text label is shifted around such that its lower left
corner is at the text anchor of the node.
More complicated shapes may have more than one text label. Nodes of such shapes are called multipart
nodes. The different node parts are simply the different text labels. For example, a uml class shape might
have a class name part, a method part and an attributes part. Indeed, single part nodes are a special
case of multipart nodes: They only have one part named text.
When a shape is declared, you must specify the node parts. There is a simple command called \nodeparts
that takes a list of the part names as input. When you create a node of a multipart shape, for each part
of the node you must have set up a TEX-box containing the text of the part. For a part named XYZ you
must set up the box \pgfnodepartXYZbox. The box will be placed at the anchor XYZ. See the description of
\pgfmultipartnode for more details.
101.2
Creating Nodes
101.2.1
Creating Simple Nodes
\pgfnode{hshapei}{hanchor i}{hlabel texti}{hnamei}{hpath usage command i}
This command creates a new node. The hshapei of the node must have been declared previously using
\pgfdeclareshape.
The shape is shifted such that the hanchor i is at the origin. In order to place the shape somewhere else,
use the coordinate transformation prior to calling this command.
The hnamei is a name for later reference. If no name is given, nothing will be “saved” for the node, it
will just be drawn.
The hpath usage command i is executed for the background and the foreground path (if the shape defines
them).
orld
Hello W
Hello World
\begin{tikzpicture}
\draw[help lines] (0,0) grid (4,3);
{
\pgftransformshift{\pgfpoint{1.5cm}{1cm}}
\pgfnode{rectangle}{north}{Hello World}{hellonode}{\pgfusepath{stroke}}
}
{
\color{red!20}
\pgftransformrotate{10}
\pgftransformshift{\pgfpoint{3cm}{1cm}}
\pgfnode{rectangle}{center}
{\color{black}Hello World}{hellonode}{\pgfusepath{fill}}
}
\end{tikzpicture}
As can be seen, all coordinate transformations are also applied to the text of the shape. Sometimes, it is desirable that the transformations are applied to the point where the shape will be
1026
anchored, but you do not wish the shape itself to the transformed. In this case, you should call
\pgftransformresetnontranslations prior to calling the \pgfnode command.
Hello World
\begin{tikzpicture}
\draw[help lines] (0,0) grid (4,3);
{
\color{red!20}
\pgftransformrotate{10}
\pgftransformshift{\pgfpoint{3cm}{1cm}}
\pgftransformresetnontranslations
\pgfnode{rectangle}{center}
{\color{black}Hello World}{hellonode}{\pgfusepath{fill}}
}
\end{tikzpicture}
The hlabel texti is typeset inside the TEX-box \pgfnodeparttextbox. This box is shown at the text
anchor of the node, if the node has a text part. See the description of \pgfmultipartnode for details.
101.2.2
Creating Multi-Part Nodes
\pgfmultipartnode{hshapei}{hanchor i}{hnamei}{hpath usage command i}
This command is the more general (and less user-friendly) version of the \pgfnode command. While
the \pgfnode command can only be used for shapes that have a single part (which is the case for most
shapes), this command can also be used with multi-part nodes.
When this command is called, for each node part of the node you must have set up one TEX-box. Suppose
the shape has two parts: The text part and the lower part. Then, prior to calling \pgfmultipartnode,
you must have set up the boxes \pgfnodeparttextbox and \pgfnodepartlowerbox. These boxes may
contain any TEX-text. The shape code will then compute the positions of the shape’s anchors based
on the sizes of the these shapes. Finally, when the node is drawn, the boxes are placed at the anchor
positions text and lower.
q1
01
\setbox\pgfnodeparttextbox=\hbox{$q_1$}
\setbox\pgfnodepartlowerbox=\hbox{01}
\begin{pgfpicture}
\pgfmultipartnode{circle split}{center}{my state}{\pgfusepath{stroke}}
\end{pgfpicture}
Note: Be careful when using the \setbox command inside a {pgfpicture} command. You will have
to use \pgfinterruptpath at the beginning of the box and \endpgfinterruptpath at the end of the
box to make sure that the box is typeset correctly. In the above example this problem was sidestepped
by moving the box construction outside the environment.
Note: It is not necessary to use \newbox for every node part name. Although you need a different box
for each part of a single shape, two different shapes may very well use the same box even when the
names of the parts are different. Suppose you have a circle split shape that has a lower part and
you have a uml class shape that has a methods part. Then, in order to avoid exhausting TEX’s limited
number of box registers, you can say
\newbox\pgfnodepartlowerbox
\let\pgfnodepartmethodsbox=\pgfnodepartlowerbox
Also, when you have a node part name with spaces like class name, it may be useful to create an
alias:
\newbox\mybox
\expandafter\let\csname pgfnodepartclass namebox\endcsname=\mybox
\pgfcoordinate{hnamei}{hcoordinatei}
This command creates a node of shape coordinate at the given hcoordinatei. Exactly the same effect
can be achieved using first a shift of the coordinate system to hcoordinatei, followed by creating a node
of shape coordinate named hnamei. However, this command is easier and more natural to use and,
more importantly, it is much faster.
1027
\pgfnodealias{hnew namei}{hexisting nodei}
This command does not actually create a new node. Rather, it allows you to subsequently access the
node hexisting nodei using the name hnew namei.
\pgfnoderename{hnew namei}{hexisting nodei}
This command renames an existing node.
There are a number of values that have an influence on the size of a node. These values are stored in the
following keys.
(no default, initially 1pt)
/pgf/minimum width=hdimensioni
alias /tikz/minimum width
This key stores the recommended minimum width of a shape. Thus, when a shape is drawn and when
the shape’s width would be smaller than hdimensioni, the shape’s width is enlarged by adding some
empty space.
Note that this value is just a recommendation. A shape may choose to ignore this key.
\begin{tikzpicture}
\draw[help lines] (-2,0) grid (2,1);
Hello World
\pgfset{minimum width=3cm}
\pgfnode{rectangle}{center}{Hello World}{}{\pgfusepath{stroke}}
\end{tikzpicture}
(no default, initially 1pt)
/pgf/minimum height=hdimensioni
alias /tikz/minimum height
Works like /pgf/minimum width.
(no default)
/pgf/minimum size=hdimensioni
alias /tikz/minimum size
This style both /pgf/minimum width and /pgf/minimum height to hdimensioni.
(no default, initially 0.3333em)
/pgf/inner xsep=hdimensioni
alias /tikz/inner xsep
This key stores the recommended horizontal inner separation between the label text and the background
path. As before, this value is just a recommendation and a shape may choose to ignore this key.
\begin{tikzpicture}
\draw[help lines] (-2,0) grid (2,1);
Hello World
\pgfset{inner xsep=1cm}
\pgfnode{rectangle}{center}{Hello World}{}{\pgfusepath{stroke}}
\end{tikzpicture}
(no default, initially 0.3333em)
/pgf/inner ysep=hdimensioni
alias /tikz/inner ysep
Works like /pgf/inner xsep.
(no default)
/pgf/inner sep=hdimensioni
alias /tikz/inner sep
This style sets both /pgf/inner xsep and /pgf/inner ysep to hdimensioni.
(no default, initially .5\pgflinewidth)
/pgf/outer xsep=hdimensioni
alias /tikz/outer xsep
This key stores the recommended horizontal separation between the background path and the “outer
anchors.” For example, if hdimensioni is 1cm then the east anchor will be 1cm to the right of the right
border of the background path. As before, this value is just a recommendation.
1028
\begin{tikzpicture}
\draw[help lines] (-2,0) grid (2,1);
Hello World
\pgfset{outer xsep=.5cm}
\pgfnode{rectangle}{center}{Hello World}{x}{\pgfusepath{stroke}}
\pgfpathcircle{\pgfpointanchor{x}{north}}{2pt}
\pgfpathcircle{\pgfpointanchor{x}{south}}{2pt}
\pgfpathcircle{\pgfpointanchor{x}{east}}{2pt}
\pgfpathcircle{\pgfpointanchor{x}{west}}{2pt}
\pgfpathcircle{\pgfpointanchor{x}{north east}}{2pt}
\pgfusepath{fill}
\end{tikzpicture}
(no default, initially .5\pgflinewidth)
/pgf/outer ysep=hdimensioni
alias /tikz/outer ysep
Works like /pgf/outer xsep.
(no default)
/pgf/outer sep=hdimensioni
alias /tikz/outer sep
This style sets both /pgf/outer xsep and /pgf/outer ysep to hdimensioni.
101.2.3
Deferred Node Positioning
Normally, when a node is created using a command like \pgfnode, the node is immediately inserted into
the current picture. In particular, you have no chance to change the position of a created node after it has
been created. Using \pgfpositionnodelater in concert with \pgfpositionnodenow, you can create a node
whose position is determined only at some later time.
\pgfpositionnodelater{hmacro namei}
This command is not a replacement for \pgfnode. Rather, when this command is used in a scope, all
subsequent node creations in this scope will be affected in the following way: When a node is created,
it is not inserted into the current picture. Instead, it is stored in the box \pgfpositionnodelaterbox.
Furthermore, the node is not relevant for the picture’s bounding box, but a bounding box for the node
is computed and stored in the macros \pgfpositionnodelaterminx to \pgfpositionnodelatermaxy.
Then, the hmacro namei is called with the following macros set up:
\pgfpositionnodelaterbox
A box register number (0 currently) that stores the node’s paths and texts. You should move the
contents of this box to a box of your choice inside hmacro namei.
\pgfpositionnodelatername
The name of the just-created-node. This name will be the originally “desired” name of the box plus
the fixed prefix not yet positionedPGFINTERNAL. The idea is to ensure that the original name
is not inadvertently used before the node is actually positioned. When \pgfpositionnodenow is
called, it will change the name to the original name.
\pgfpositionnodelaterminx
The minimal x-position of a bounding box of the node. This bounding box refers to the node
when it is positioned with the anchor at the origin. It is guaranteed, that this macro will contain
a dimension in the format hnumber ipt.
\pgfpositionnodelaterminy
\pgfpositionnodelatermaxx
\pgfpositionnodelatermaxy
Once a late node has been created, you can add arbitrary code in the same picture. Then, at some later
point, you call \pgfpositionnodenow to finally position the node at a given position. At this point,
the above macros must have the exact same values they had when hmacro namei was called. Note that
1029
the above macros are local to a scope that ends right after the call to hmacro namei, so it is your job
to copy the values to safety inside hmacro namei.
The following two macros will also be set inside the call to hmacro namei, but they are only “informative”
in the sense that you need not restore these macros when \pgfpositionnodenow is called.
\pgfpositionnodelaterpath
This macro stores the path of the background of the node. See Section 115 for an overview of how
these paths are encode.
By setting hmacro namei to \relax (which is the default), you can switch off the whole mechanism.
When a picture is interrupted, this is done automatically.
\pgfpositionnodenow{hcoordinatei}
This command is used to position a node that has previously been created using the command
\pgfpositionnodelater. When \pgfpositionnodenow is called, the macros and boxes mentioned
in the description of \pgfpositionnodenow must be set to the value they had when the hmacro namei
was called. Provided this is the case, this command will insert the box into the current picture, shifted
by hcoordinatei. Then, the late code (see below) is called. Subsequently, you can refer to the node with
its original name as if it had just been created.
H
rld
wo
o
l
el
\newbox\mybox
\def\mysaver{
\global\setbox\mybox=\box\pgfpositionnodelaterbox
\global\let\myname=\pgfpositionnodelatername
\global\let\myminx=\pgfpositionnodelaterminx
\global\let\myminy=\pgfpositionnodelaterminy
\global\let\mymaxx=\pgfpositionnodelatermaxx
\global\let\mymaxy=\pgfpositionnodelatermaxy
}
\begin{tikzpicture}
{
\pgfpositionnodelater{\mysaver}
\node [fill=blue!20,below,rotate=30] (hi) {Hello world};
}
\draw [help lines] (0,0) grid (3,2);
\let\pgfpositionnodelatername=\myname
\let\pgfpositionnodelaterminx=\myminx
\let\pgfpositionnodelaterminy=\myminy
\let\pgfpositionnodelatermaxx=\mymaxx
\let\pgfpositionnodelatermaxy=\mymaxy
\setbox\pgfpositionnodelaterbox=\box\mybox
\pgfpositionnodenow{\pgfqpoint{2cm}{2cm}}
\draw (hi) -- (0,0);
\end{tikzpicture}
\pgfnodepostsetupcode{hnode namei}{hcodei}
When you call this macro inside a scope for which the \pgfpositionnodelater has been called, the
hcodei will be stored internally. Later, when the node named hnode namei is actually positioned using
\pgfpositionnodenow, the hcodei will be executed. When this macro is called multiple times with the
same hnode namei, the hcodei accumulates. However, When \pgfpositionnodenow is called, the code
stored for the node is cleared.
The main purpose of this mechanism is to allow Tik Z to store so-called “late options” with a node that
will be positioned only later.
101.3
Using Anchors
Each shape defines a set of anchors. We saw already that the anchors are used when the shape is drawn:
the shape is placed in such a way that the given anchor is at the origin (which in turn is typically translated
somewhere else).
1030
One has to look up the set of anchors of each shape, there is no “default” set of anchors, except for the
center anchor, which should always be present. Also, most shapes will declare anchors like north or east,
but this is not guaranteed.
101.3.1
Referencing Anchors of Nodes in the Same Picture
Once a node has been defined, you can refer to its anchors using the following commands:
\pgfpointanchor{hnodei}{hanchor i}
This command is another “point command” like the commands described in Section 96. It returns the
coordinate of the given hanchor i in the given hnodei. The command can be used in commands like
\pgfpathmoveto.
!
rld
o
W
llo
He
\begin{pgfpicture}
\pgftransformrotate{30}
\pgfnode{rectangle}{center}{Hello World!}{x}{\pgfusepath{stroke}}
\pgfpathcircle{\pgfpointanchor{x}{north}}{2pt}
\pgfpathcircle{\pgfpointanchor{x}{south}}{2pt}
\pgfpathcircle{\pgfpointanchor{x}{east}}{2pt}
\pgfpathcircle{\pgfpointanchor{x}{west}}{2pt}
\pgfpathcircle{\pgfpointanchor{x}{north east}}{2pt}
\pgfusepath{fill}
\end{pgfpicture}
In the above example, you may have noticed something curious: The rotation transformation is still in
force when the anchors are invoked, but it does not seem to have an effect. You might expect that the
rotation should apply to the already rotated points once more.
However, \pgfpointanchor returns a point that takes the current transformation matrix into account:
The inverse transformation to the current coordinate transformation is applied to an anchor point before
returning it.
This behavior may seem a bit strange, but you will find it very natural in most cases. If you really want
to apply a transformation to an anchor point (for example, to “shift it away” a little bit), you have to
invoke \pgfpointanchor without any transformations in force. Here is an example:
ld!
r
Wo
o
l
l
He
\begin{pgfpicture}
\pgftransformrotate{30}
\pgfnode{rectangle}{center}{Hello World!}{x}{\pgfusepath{stroke}}
{
\pgftransformreset
\pgfpointanchor{x}{east}
\xdef\mycoordinate{\noexpand\pgfpoint{\the\pgf@x}{\the\pgf@y}}
}
\pgfpathcircle{\mycoordinate}{2pt}
\pgfusepath{fill}
\end{pgfpicture}
A special situation arises when the hnodei lies in a picture different from the current picture. In this
case, if you have not told pgf that the picture should be “remembered,” the hnodei will be treated as if
it lay in the current picture. For example, if the hnodei was at position (3, 2) in the original picture, it is
treated as if it lay at position (3, 2) in the current picture. However, if you have told pgf to remember
the picture position of the node’s picture and also of the current picture, then \pgfpointanchor will
return a coordinate that corresponds to the position of the node’s anchor on the page, transformed into
the current coordinate system. For examples and more details see Section 101.3.2.
\pgfpointshapeborder{hnodei}{hpointi}
This command returns the point on the border of the shape that lies on a straight line from the center
of the node to hpointi. For complex shapes it is not guaranteed that this point will actually lie on the
border, it may be on the border of a “simplified” version of the shape.
1031
d!
orl
W
llo
He
101.3.2
\begin{pgfpicture}
\begin{pgfscope}
\pgftransformrotate{30}
\pgfnode{rectangle}{center}{Hello World!}{x}{\pgfusepath{stroke}}
\end{pgfscope}
\pgfpathcircle{\pgfpointshapeborder{x}{\pgfpoint{2cm}{1cm}}}{2pt}
\pgfpathcircle{\pgfpoint{2cm}{1cm}}{2pt}
\pgfpathcircle{\pgfpointshapeborder{x}{\pgfpoint{-1cm}{1cm}}}{2pt}
\pgfpathcircle{\pgfpoint{-1cm}{1cm}}{2pt}
\pgfusepath{fill}
\end{pgfpicture}
Referencing Anchors of Nodes in Different Pictures
As a picture is typeset, pgf keeps track of the positions of all nodes inside the picture. What pgf does not
remember is the position of the picture itself on the page. Thus, if you define a node in one picture and then
try to reference this node while another picture is typeset, pgf will only know the position of the nodes that
you try to typeset inside the original picture, but it will not know where this picture lies. What is missing
is the relative positioning of the two pictures.
To overcome this problem, you need to tell pgf that it should remember the position of pictures on a
page. If these positions are remembered, then pgf can compute the offset between the pictures and make
nodes in different pictures accessible.
Determining the positions of pictures on the page is, alas, not-so-easy. Because of this, pgf does not do
so automatically. Rather, you have to proceed as follows:
1. You have to use a backend driver that supports position tracking. pdfTEX is one such driver, dvips
currently is not.
2. You have to say \pgfrememberpicturepositiononpagetrue somewhere before or inside every picture
• in which you wish to reference a node and
• from which you wish to reference a node in another picture.
The second item is important since pgf does not only need to know the position of the picture in
which the node you wish to reference lies, but it also needs to know where the current picture lies.
3. You typically have to run TEX twice (depending on the backend driver) since the position information
typically gets written into an external file on the first run and is available only on the second run.
4. You have to switch off automatic bounding bound computations. The reason is that the node in the
other picture should not influence the size of the bounding box of the current picture. You should say
\pgfusepath{use as bounding box} before using a coordinate in another picture.
101.4
Special Nodes
There are several special nodes that are always defined and which you should not attempt to redefine.
Predefined node current bounding box
This node is of shape rectangle. Unlike normal nodes, its size changes constantly and always reflects
the size of the bounding box of the current picture. This means that, for instance, that
\pgfpointanchor{current bounding box}{south east}
returns the lower left corner of the bounding box of the current picture.
Predefined node current path bounding box
This node is also of shape rectangle. Its size is the size of the bounding box of the current path.
Predefined node current subpath start
This node is of shape coordinate and is at the beginning of the current subpath. This is the position
of the last move-to operation.
1032
Predefined node current page
This node is inside a virtual remembered picture. The size of this node is the size of the current page.
This means that if you create a remembered picture and inside this picture you reference an anchor of
this node, you reference an absolute position on the page. To demonstrate the effect, the following code
puts some text in the lower left corner of the current page. Note that this works only if the backend
driver supports it, otherwise the text is inserted right here.
\pgfrememberpicturepositiononpagetrue
\begin{pgfpicture}
\pgfusepath{use as bounding box}
\pgftransformshift{\pgfpointanchor{current page}{south west}}
\pgftransformshift{\pgfpoint{1cm}{1cm}}
\pgftext[left,base]{
\textcolor{red}{
Text absolutely positioned in
the lower left corner.}
}
\end{pgfpicture}
There is also an option that allows you to create new special nodes quite similar to the above:
/pgf/local bounding box=hnode namei
(no default)
alias /tikz/local bounding box
This defines a new node hnode namei whose size is the bounding box around all objects in the current
scope starting at the position where this option was given. After the end of the scope, the hnode namei is
still available. You can use this option to keep track of the size of a certain area. Note that excessive use
of this option (keeping track of dozens of bounding boxes at the same time) will slow things down.
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
{ [local bounding box=outer box]
\draw (1,1) circle (.5) [local bounding box=inner box] (2,2) circle (.5);
}
\draw
(outer box.south west) rectangle (outer box.north east);
\draw[red] (inner box.south west) rectangle (inner box.north east);
\end{tikzpicture}
101.5
Declaring New Shapes
There are only three predefined shapes, see Section 67.2, so there must be some way of defining new shapes.
Defining a shape is, unfortunately, a not-quite-trivial process. The reason is that shapes need to be both very
flexible (their size will vary greatly according to circumstances) and they need to be constructed reasonably
“fast.” pgf must be able to handle pictures with several hundreds of nodes and documents with thousands
of nodes in total. It would not do if pgf had to compute and store, say, dozens of anchor positions for every
node.
101.5.1
What Must Be Defined For a Shape?
In order to define a new shape, you must provide:
• a shape name,
• code for computing the saved anchors and saved dimensions,
• code for computing anchor positions in terms of the saved anchors,
• optionally code for the background path and foreground path,
• optionally code for things to be drawn before or behind the background and foreground paths.
• optionally a list of node parts.
1033
Text absolutely positioned in the lower left corner.
101.5.2
Normal Anchors Versus Saved Anchors
Anchors are special places in a shape. For example, the north east anchor, which is a normal anchor, lies at
the upper right corner of the rectangle shape, as does \northeast, which is a saved anchor. The difference
is the following: saved anchors are computed and stored for each node, anchors are only computed as needed.
The user only has access to the normal anchors, but a normal anchor can just “copy” or “pass through” the
location of a saved anchor.
The idea behind all this is that a shape can declare a very large number of normal anchors, but when
a node of this shape is created, these anchors are not actually computed. However, this causes a problem:
When we wish to reference an anchor of a node at some later time, we must still be able to compute the
position of the anchor. For this, we may need a lot of information: What was the transformation matrix
that was in force when the node was created? What was the size of the text box? What were the values of
the different separation dimensions? And so on.
To solve this problem, pgf will always compute the locations of all saved anchors and store these
positions. Then, when an normal anchor position is requested later on, the anchor position can be given just
from knowing where the locations of the saved anchors are.
As an example, consider the rectangle shape. For this shape two anchors are saved: The \northeast
corner and the \southwest corner. A normal anchor like north west can now easily be expressed in terms
of these coordinates: Take the x-position of the \southwest point and the y-position of the \northeast
point. The rectangle shape currently defines 13 normal anchors, but needs only two saved anchors. Adding
new anchors like a south south east anchor would not increase the memory and computation requirements
of pictures.
All anchors (both saved and normal) are specified in a local shape coordinate space. This is also true for
the background and foreground paths. The \pgfnode macro will automatically apply appropriate transformations to the coordinates so that the shape is shifted to the right anchor or otherwise transformed.
101.5.3
Command for Declaring New Shapes
The following command declares a new shape:
\pgfdeclareshape{hshape namei}{hshape specificationi}
This command declares a new shape named hshape namei. The shape name can later be used in
commands like \pgfnode.
The hshape specificationi is some TEX code containing calls to special commands that are only defined
inside the hshape specificationi (similarly to commands like \draw that are only available inside the
{tikzpicture} environment).
Example: Here is the code of the coordinate shape:
\pgfdeclareshape{coordinate}
{
\savedanchor\centerpoint{%
\pgf@x=.5\wd\pgfnodeparttextbox%
\pgf@y=.5\ht\pgfnodeparttextbox%
\advance\pgf@y by -.5\dp\pgfnodeparttextbox%
}
\anchor{center}{\centerpoint}
\anchorborder{\centerpoint}
}
The special commands are explained next. In the examples given for the special commands a new shape
will be constructed, which we might call simple rectangle. It should behave like the normal rectangle
shape, only without bothering about the fine details like inner and outer separations. The skeleton for
the shape is the following.
\pgfdeclareshape{simple rectangle}{
...
}
\nodeparts{hlist of node partsi}
This command declares which parts make up nodes of this shape. A node part is a (possibly empty)
text label that is drawn when a node of the shape is created.
1034
By default, a shape has just one node part called text. However, there can be several node parts.
For example, the circle split shape has two parts: the text part, which shows that the upper
text, and a lower part, which shows the lower text. For the circle split shape the \nodeparts
command was called with the argument {text,lower}.
When a multipart node is created, the text labels are drawn in the sequences listed in the hlist of
node partsi. For each node part, you must have declared one anchor and the TEX-box of the part
is placed at this anchor. For a node part called XYZ the TEX-box \pgfnodepartXYZbox is placed
at anchor XYZ.
\savedanchor{hcommand i}{hcodei}
This command declares a saved anchor. The argument hcommand i should be a TEX macro name
like \centerpoint.
The hcodei will be executed each time \pgfnode (or \pgfmultipartnode) is called to create a node
of the shape hshape namei. When the hcodei is executed, the TEX-boxes of the node parts will
contain the text labels of the node. Possibly, these box are void. For example, if there is just a
text part, the node \pgfnodeparttextbox will be set up when the hcodei is executed.
The hcodei can use the width, height, and depth of the box(es) to compute the location of the saved
anchor. In addition, the hcodei can take into account the values of dimensions like \pgfshapeminwidth or \pgfshapeinnerxsep. Furthermore, the hcodei can take into consideration the values
of any further shape-specific variables that are set at the moment when \pgfnode is called.
The net effect of the hcodei should be to set the two TEX dimensions \pgf@x and \pgf@y. One way
to achieve this is to say \pgfpoint{hx valuei}{hy valuei} at the end of the hcodei, but you can also
just set these variables. The values that \pgf@x and \pgf@y have after the code has been executed,
let us call them x and y, will be recorded and stored together with the node that is created by the
command \pgfnode.
The macro hcommand i is defined to be \pgfpoint{x}{y}. However, the hcommand i is only locally
defined while anchor positions are being computed. Thus, it is possible to use very simple names
for hcommand i, like \center or \a, without causing a name-clash. (To be precise, very simple
hcommand i names will clash with existing names, but only locally inside the computation of anchor
positions; and we do not need the normal \center command during these computations.)
For our simple rectangle shape, we will need only one saved anchor: The upper right corner.
The lower left corner could either be the origin or the “mirrored” upper right corner, depending
on whether we want the text label to have its lower left corner at the origin or whether the text
label should be centered on the origin. Either will be fine, for the final shape this will make no
difference since the shape will be shifted anyway. So, let us assume that the text label is centered
on the origin (this will be specified later on using the text anchor). We get the following code for
the upper right corner:
\savedanchor{\upperrightcorner}{
\pgf@y=.5\ht\pgfnodeparttextbox % height of the box, ignoring the depth
\pgf@x=.5\wd\pgfnodeparttextbox % width of the box
}
If we wanted to take, say, the \pgfshapeminwidth into account, we could use the following code:
\savedanchor{\upperrightcorner}{
\pgf@y=.\ht\pgfnodeparttextbox % height of the box
\pgf@x=.\wd\pgfnodeparttextbox % width of the box
\setlength{\pgf@xa}{\pgfshapeminwidth}
\ifdim\pgf@x<.5\pgf@xa
\pgf@x=.5\pgf@xa
\fi
}
Note that we could not have written .5\pgfshapeminwidth since the minimum width is stored in
a “plain text macro,” not as a real dimension. So if \pgfshapeminwidth depth were 2cm, writing
.5\pgfshapeminwidth would yield the same as .52cm.
In the “real” rectangle shape the code is somewhat more complex, but you get the basic idea.
\saveddimen{hcommand i}{hcodei}
1035
This command is similar to \savedanchor, only instead of setting hcommand i to \pgfpoint{x}{y},
the hcommand i is set just to (the value of) x.
In the simple rectangle shape we might use a saved dimension to store the depth of the shape
box.
\saveddimen{\depth}{
\pgf@x=\dp\pgfnodeparttextbox
}
\savedmacro{hcommand i}{hcodei}
This command is similar to \saveddimen, only at some point in hcodei, hcommand i should be
defined appropriately, (this could be a value, or some text).
In the regular polygon shape, a saved macro is used to store the number of sides of the polygon.
\savedmacro{\sides}{\let\sides\pgfpolygonsides}
\anchor{hnamei}{hcodei}
This command declares an anchor named hnamei. Unlike for saved anchors, the hcodei will not
be executed each time a node is declared. Rather, the hcodei is only executed when the anchor is
specifically requested; either for anchoring the node during its creation or as a position in the shape
referenced later on.
The hnamei is a quite arbitrary string that is not “passed down” to the system level. Thus, names
like south or 1 or :: would all be fine.
A saved anchor is not automatically also a normal anchor. If you wish to give the users access to a
saved anchor you must declare a normal anchor that just returns the position of the saved anchor.
When the hcodei is executed, all saved anchor macros will be defined. Thus, you can reference them
in your hcodei. The effect of the hcodei should be to set the values of \pgf@x and \pgf@y to the
coordinates of the anchor.
Let us consider some example for the simple rectangle shape. First, we would like to make the
upper right corner publicly available, for example as north east:
\anchor{north east}{\upperrightcorner}
The \upperrightcorner macro will set \pgf@x and \pgf@y to the coordinates of the upper right
corner. Thus, \pgf@x and \pgf@y will have exactly the right values at the end of the anchor’s code.
Next, let us define a north west anchor. For this anchor, we can negate the \pgf@x variable:
\anchor{north west}{
\upperrightcorner
\pgf@x=-\pgf@x
}
Finally, it is a good idea to always define a center anchor, which will be the default location for a
shape.
\anchor{center}{\pgfpointorigin}
You might wonder whether we should not take into consideration that the node is not placed at
the origin, but has been shifted somewhere. However, the anchor positions are always specified in
the shape’s “private” coordinate system. The “outer” transformation that has been applied to the
shape upon its creation is applied automatically to the coordinates returned by the anchor’s hcodei.
Our simple rectangle only has one text label (node part) called text. This is the default situation, so we do not need to do anything. For the text node part we must set up a text anchor.
This anchor is used upon creation of a node to determine the lower left corner of the text label
(within the private coordinate system of the shape). By default, the text anchor is at the origin,
but you may change this. For example, we would say
1036
\anchor{text}{%
\upperrightcorner%
\pgf@x=-\pgf@x%
\pgf@y=-\pgf@y%
}
to center the text label on the origin in the shape coordinate space. Note that we could not have
written the following:
\anchor{text}{\pgfpoint{-.5\wd\pgfnodeparttextbox}{-.5\ht\pgfnodeparttextbox}}
Do you see why this is wrong? The problem is that the box \pgfnodeparttextbox will most likely
not have the correct size when the anchor is computed. After all, the anchor position might be
recomputed at a time when several other nodes have been created.
If a shape has several node parts, we would have to define an anchor for each part.
\deferredanchor{hnamei}{hcodei}
This command declares an anchor named hnamei. It works like \anchor. However, unlike for
anchors declared by \anchor, hnamei will not be expanded during the shape declaration (i.e. not
during \pgfdeclareshape). Rather, the hnamei is expanded when the node is actually used (with
\pgfnode or more likely with \node). This may be useful if the anchor name is context dependent
(depending, for example, on the value of a key).
\makeatletter
\def\foo{foo}
\pgfdeclareshape{simple shape}{%
\savedanchor{\center}{%
\pgfpointorigin}
\anchor{center}{\center}
\savedanchor{\anchorfoo}{%
\pgf@x=1cm
\pgf@y=0cm}
\deferredanchor{anchor \foo}{\anchorfoo}}
\begin{tikzpicture}
\node[simple shape]
\fill (Test1.anchor
%
\def\foo{bar}
\node[simple shape]
\fill (Test2.anchor
\end{tikzpicture}
(Test1) at (0,0) {};
foo) circle (2pt) node[below] {anchor foo anchor};
(Test2) at (2,2) {};
bar) circle (2pt) node[below] {anchor bar anchor};
\anchorborder{hcodei}
A border anchor is an anchor point on the border of the shape. What exactly is considered as the
“border” of the shape depends on the shape.
When the user requests a point on the border of the shape using the \pgfpointshapeborder
command, the hcodei will be executed to discern this point. When the execution of the hcodei
starts, the dimensions \pgf@x and \pgf@y will have been set to a location p in the shape’s coordinate
system. It is now the job of the hcodei to set up \pgf@x and \pgf@y such that they specify the
point on the shape’s border that lies on a straight line from the shape’s center to the point p.
Usually, this is a somewhat complicated computation, involving many case distinctions and some
basic math.
For our simple rectangle we must compute a point on the border of a rectangle whose one corner
is the origin (ignoring the depth for simplicity) and whose other corner is \upperrightcorner. The
following code might be used:
\anchorborder{%
% Call a function that computes a border point. Since this
% function will modify dimensions like \pgf@x, we must move them to
% other dimensions.
\@tempdima=\pgf@x
\@tempdimb=\pgf@y
\pgfpointborderrectangle{\pgfpoint{\@tempdima}{\@tempdimb}}{\upperrightcorner}
}
1037
\backgroundpath{hcodei}
This command specifies the path that “makes up” the background of the shape. Note that the
shape cannot prescribe what is going to happen with the path: It might be drawn, shaded, filled, or
even thrown away. If you want to specify that something should “always” happen when this shape
is drawn (for example, if the shape is a stop-sign, we always want it to be filled with a red color),
you can use commands like \beforebackgroundpath, explained below.
When the hcodei is executed, all saved anchors will be in effect. The hcodei should contain path
construction commands.
For our simple rectangle, the following code might be used:
\backgroundpath{
\pgfpathrectanglecorners
{\upperrightcorner}
{\pgfpointscale{-1}{\upperrightcorner}}
}
As the name suggests, the background path is used “behind” the text labels. Thus, this path is
used first, then the text labels are drawn, possibly obscuring part of the path.
\foregroundpath{hcodei}
This command works like \backgroundpath, only it is invoked after the text labels have been
drawn. This means that this path can possibly obscure (part of) the text labels.
\behindbackgroundpath{hcodei}
Unlike the previous two commands, hcodei should not only construct a path, it should also use this
path in whatever way is appropriate. For example, the hcodei might fill some area with a uniform
color.
Whatever the hcodei does, it does it first. This means that any drawing done by hcodei will be even
behind the background path.
Note that the hcodei is protected with a {pgfscope}.
\beforebackgroundpath{hcodei}
This command works like \behindbackgroundpath, only the hcodei is executed after the background path has been used, but before the texts label are drawn.
\behindforegroundpath{hcodei}
The hcodei is executed after the text labels have been drawn, but before the foreground path is
used.
\beforeforegroundpath{hcodei}
This hcodei is executed at the very end.
\inheritsavedanchors[from={hanother shape namei}]
This command allows you to inherit the code for saved anchors from hanother shape namei. The
idea is that if you wish to create a new shape that is just a small modification of a another shape,
you can recycle the code used for hanother shape namei.
The effect of this command is the same as if you had called \savedanchor and \saveddimen for
each saved anchor or saved dimension declared in hanother shape namei. Thus, it is not possible
to “selectively” inherit only some saved anchors, you always have to inherit all saved anchors from
another shape. However, you can inherit the saved anchors of more than one shape by calling this
command several times.
\inheritbehindbackgroundpath[from={hanother shape namei}]
This command can be used to inherit the code used for the drawings behind the background path
from hanother shape namei.
\inheritbackgroundpath[from={hanother shape namei}]
Inherits the background path code from hanother shape namei.
1038
\inheritbeforebackgroundpath[from={hanother shape namei}]
Inherits the before background path code from hanother shape namei.
\inheritbehindforegroundpath[from={hanother shape namei}]
Inherits the behind foreground path code from hanother shape namei.
\inheritforegroundpath[from={hanother shape namei}]
Inherits the foreground path code from hanother shape namei.
\inheritbeforeforegroundpath[from={hanother shape namei}]
Inherits the before foreground path code from hanother shape namei.
\inheritanchor[from={hanother shape namei}]{hnamei}
Inherits the code of one specific anchor named hnamei from hanother shape namei. Thus, unlike
saved anchors, which must be inherited collectively, normal anchors can and must be inherited
individually.
\inheritanchorborder[from={hanother shape namei}]
Inherits the border anchor code from hanother shape namei.
The following example shows how a shape can be defined that relies heavily on inheritance:
Remark
Use Case
\pgfdeclareshape{document}{
\inheritsavedanchors[from=rectangle] % this is nearly a rectangle
\inheritanchorborder[from=rectangle]
\inheritanchor[from=rectangle]{center}
\inheritanchor[from=rectangle]{north}
\inheritanchor[from=rectangle]{south}
\inheritanchor[from=rectangle]{west}
\inheritanchor[from=rectangle]{east}
% ... and possibly more
\backgroundpath{% this is new
% store lower right in xa/ya and upper right in xb/yb
\southwest \pgf@xa=\pgf@x \pgf@ya=\pgf@y
\northeast \pgf@xb=\pgf@x \pgf@yb=\pgf@y
% compute corner of ‘‘flipped page’’
\pgf@xc=\pgf@xb \advance\pgf@xc by-5pt % this should be a parameter
\pgf@yc=\pgf@yb \advance\pgf@yc by-5pt
% construct main path
\pgfpathmoveto{\pgfpoint{\pgf@xa}{\pgf@ya}}
\pgfpathlineto{\pgfpoint{\pgf@xa}{\pgf@yb}}
\pgfpathlineto{\pgfpoint{\pgf@xc}{\pgf@yb}}
\pgfpathlineto{\pgfpoint{\pgf@xb}{\pgf@yc}}
\pgfpathlineto{\pgfpoint{\pgf@xb}{\pgf@ya}}
\pgfpathclose
% add little corner
\pgfpathmoveto{\pgfpoint{\pgf@xc}{\pgf@yb}}
\pgfpathlineto{\pgfpoint{\pgf@xc}{\pgf@yc}}
\pgfpathlineto{\pgfpoint{\pgf@xb}{\pgf@yc}}
\pgfpathlineto{\pgfpoint{\pgf@xc}{\pgf@yc}}
}
}\hskip-1.2cm
\begin{tikzpicture}
\node[shade,draw,shape=document,inner sep=2ex] (x) {Remark};
\node[fill=yellow!80!black,draw,ellipse,double]
at ([shift=(-80:3cm)]x) (y) {Use Case};
\draw[dashed] (x) -- (y);
\end{tikzpicture}
1039
102
Matrices
\usepgfmodule{matrix}
\usepgfmodule[matrix]
% LATEX and plain TEX and pure pgf
% ConTEXt and pure pgf
The present section documents the commands of this module.
102.1
Overview
Matrices are a mechanism for aligning several so-called cell pictures horizontally and vertically. The resulting
alignment is placed in a normal node and the command for creating matrices, \pgfmatrix, takes options
very similar to the \pgfnode command.
In the following, the basic idea behind the alignment mechanism is explained first. Then the command
\pgfmatrix is explained. At the end of the section, additional ways of modifying the width of columns and
rows are discussed.
102.2
Cell Pictures and Their Alignment
A matrix consists of rows of cells. Cells are separated using the special command \pgfmatrixnextcell,
rows are ended using the command \pgfmatrixendrow (the command \\ is set up to mean the same as
\pgfmatrixendrow by default). Each cell contains a cell picture, although cell pictures are not complete
pictures as they lack layers. However, each cell picture has its own bounding box like a normal picture does.
These bounding boxes are important for the alignment as explained in the following.
Each cell picture will have an origin somewhere in the picture (or even outside the picture). The position
of these origins are important for the alignment: On each row the origins will be on the same horizontal line
and for each column the origins will also be on the same vertical line. These two requirements mean that
the cell pictures may need to be shifted around so that the origins wind up on the same lines. The top of a
row is given by the top of the cell picture whose bounding box’s maximum y-position is largest. Similarly,
the bottom of a row is given by the bottom of the cell picture whose bounding box’s minimum y-position is
the most negative. Similarly, the left end of a row is given by the left end of the cell whose bounding box’s
x-position is the most negative; and similarly for the right end of a row.
\begin{tikzpicture}[x=3mm,y=3mm,fill=blue!50]
\def\atorig#1{\node[black] at (0,0) {\tiny #1};}
1
5
102.3
2
6
3
7
4
8
\pgfmatrix{rectangle}{center}{mymatrix}
{\pgfusepath{}}{\pgfpointorigin}{}
{
\fill (0,-3) rectangle (1,1);\atorig1
\fill (-1,0) rectangle (1,1);\atorig2
\fill (-1,-2) rectangle (0,0);\atorig3
\fill (-1,-1) rectangle (0,3);\atorig4
\fill (-1,0) rectangle (4,1);\atorig5
\fill (0,-1) rectangle (1,1);\atorig6
\fill (0,0)
rectangle (1,4);\atorig7
\fill (-1,-1) rectangle (0,0);\atorig8
}
\end{tikzpicture}
\pgfmatrixnextcell
\pgfmatrixnextcell
\pgfmatrixnextcell
\\
\pgfmatrixnextcell
\pgfmatrixnextcell
\pgfmatrixnextcell
\\
The Matrix Command
All matrices are typeset using the following command:
\pgfmatrix{hshapei}{hanchor i}{hnamei}{husagei}{hshifti}{hpre-codei}{hmatrix cellsi}
This command creates a node that contains a matrix. The name of the node is hnamei, its shape is
hshapei and the node is anchored at hanchor i.
The hmatrix cell i parameter contains the cells of the matrix. In each cell drawing commands may be
given, which create a so-called cell picture. For each cell picture a bounding box is computed and the
cells are aligned according to the rules outlined in the previous section.
The resulting matrix is used as the text box of the node. As for a normal node, the husagei commands
are applied, so that the path(s) of the resulting node is (are) stroked or filled or whatever.
1040
Specifying the cells and rows. Even though this command uses \halign internally, there are two
special rules for indicating cells:
1. Cells in the same row must be separated using the macro \pgfmatrixnextcell rather than &.
Using & will result in an error message.
However, you can make & an active character and have it expand to \pgfmatrixnextcell. This
way, it will “look” as if & is used.
2. Rows are ended using the command \pgfmatrixendrow, but \\ is set up to mean the same
by default. However, some environments like {minipage} redefine \\, so it is good to have
\pgfmatrixendrow as a “fallback.”
3. Every row including the last row must be ended using the command \\ or \pgfmatrixendrow.
Both \pgfmatrixnextcell and \pgfmatrixendrow (and, thus, also \\) take an optional argument as
explained in the Section 102.4
a b
c d
\begin{tikzpicture}
\pgfmatrix{rectangle}{center}{mymatrix}
{\pgfusepath{}}{\pgfpointorigin}{}
{
\node {a}; \pgfmatrixnextcell \node {b}; \pgfmatrixendrow
\node {c}; \pgfmatrixnextcell \node {d}; \pgfmatrixendrow
}
\end{tikzpicture}
Anchoring matrices at nodes inside the matrix. The parameter hshifti is an additional negative
shift for the node. Normally, such a shift could be given beforehand (that is, the shift could be preapplied
to the current transformation matrix). However, when hshifti is evaluated, you can refer to temporary
positions of nodes inside the matrix. In detail, the following happens: When the matrix has been
typeset, all nodes in the matrix temporarily get assigned their positions in the matrix box. The origin
of this coordinate system is at the left baseline end of the matrix box, which corresponds to the text
anchor. The position hshifti is then interpreted inside this coordinate system and then used for shifting.
This allows you to use the parameter hshifti in the following way: If you use text as the hanchor i and
specify \pgfpointanchor{inner node}{some anchor} for the parameter hshifti, where inner node is
a node that is created in the matrix, then the whole matrix will be shifted such that inner node.some
anchor lies at the origin of the whole picture.
Rotations and scaling. The matrix node is never rotated or shifted, because the current coordinate
transformation matrix is reset (except for the translational part) at the beginning of \pgfmatrix. This
is intentional and will not change in the future. If you need to rotate the matrix, you must install an
appropriate canvas transformation yourself.
However, nodes and stuff inside the cell pictures can be rotated and scaled normally.
Callbacks. At the beginning and at the end of each cell the special macros \pgfmatrixbegincode,
\pgfmatrixendcode and possibly \pgfmatrixemptycode are called. The effect is explained in Section 102.5.
Executing extra code. The parameter hpre-codei is executed at the beginning of the outermost
TEX-group enclosing the matrix node. It is inside this TEX-group, but outside the matrix itself. It can
be used for different purposes:
1. It can be used to simplify the next cell macro. For example, saying \let\&=\pgfmatrixnextcell
allows you to use \& instead of \pgfmatrixnextcell. You can also set the catcode of & to active.
2. It can be used to issue an \aftergroup command. This allows you to regain control after the
\pgfmatrix command. (If you do not know the \aftergroup command, you are probably blessed
with a simple and happy life.)
Special considerations concerning macro expansion. As said before, the matrix is typeset using
\halign internally. This command does a lot of strange and magic things like expanding the first macro
of every cell in a most unusual manner. Here are some effects you may wish to be aware of:
1041
• It is not necessary to actually mention \pgfmatrixnextcell or \pgfmatrixendrow inside the
hmatrix cellsi. It suffices that the macros inside hmatrix cellsi expand to these macros sooner or
later.
• In particular, you can define clever macros that insert columns and rows as needed for special
effects.
102.4
Row and Column Spacing
It is possible to control the space between columns and rows rather detailedly. Two commands are important
for the row spacing and two commands for the column spacing.
\pgfsetmatrixcolumnsep{hsep listi}
This macro sets the default separation list for columns. The details of the format of this list are explained
in the description of the next command.
\pgfmatrixnextcell[hadditional sep listi]
This command has two purposes: First, it is used to separate cells. Second, by providing the optional
argument hadditional sep listi you can modify the spacing between the columns that are separated by
this command.
The optional hadditional sep listi may only be provided when the \pgfmatrixnextcell command
starts a new column. Normally, this will only be the case in the first row, but sometimes a later row
has more elements than the first row. In this case, the \pgfmatrixnextcell commands that start the
new columns in the later row may also have the optional argument. Once a column has been started,
subsequent uses of this optional argument for the column have no effect.
To determine the space between the two columns that are separated by \pgfmatrixnextcell, the
following algorithm is executed:
1. Both the default separation list (as set up by \pgfsetmatrixcolumnsep) and the hadditional sep
listi are processed, in this order. If the hadditional sep listi argument is missing, only the default
separation list is processed.
2. Both lists may contain dimensions, separated by commas, as well as occurrences of the keywords
between origins and between borders.
3. All dimensions occurring in either list are added together to arrive at a dimension d.
4. The last occurrence of either of the keywords is located. If neither keyword is present, we proceed
as if between borders were present.
At the end of the algorithm, a dimension d has been computed and one of the two modes between
borders and between origins has been determined. Depending on which mode has been determined,
the following happens:
• For the between borders mode, an additional horizontal space of d is added between the two
columns. Note that d may be negative.
• For the between origins mode, the spacing between the two columns is computed differently:
Recall that the origins of the cell pictures in both pictures lie on two vertical lines. The spacing
between the two columns is set up such that the horizontal distance between these two lines is
exactly d.
This mode may only be used between columns already introduced in the first row.
All of the above rules boil down to the following effects:
• A default spacing between columns should be set up using \pgfsetmatrixcolumnsep. For example,
you might say \pgfsetmatrixcolumnsep{5pt} to have columns spaced apart by 5pt. You could
say
\pgfsetmatrixcolumnsep{1cm,between origins}
to specify that horizontal space between the origins of cell pictures in adjacent columns should be
1cm by default – regardless of the actual size of the cell pictures.
1042
• You can now use the optional argument of \pgfmatrixnextcell to locally overrule the spacing
between two columns. By saying \pgfmatrixnextcell[5pt] you add 5pt to the space between of
the two columns, regardless of the mode.
You can also (locally) change the spacing mode for these two columns. For example, even if the
normal spacing mode is between origins, you can say
\pgfmatrixnextcell[5pt,between borders]
to locally change the mode for these columns to between borders.
8
3
4
8
3
4
1 6
5 7
9 2
11mm
1
6
5
7
9
2
10mm 10mm
8
1
6
3
5
7
4
9
2
\begin{tikzpicture}[every node/.style=draw]
\pgfsetmatrixcolumnsep{1mm}
\pgfmatrix{rectangle}{center}{mymatrix}
{\pgfusepath{}}{\pgfpointorigin}{\let\&=\pgfmatrixnextcell}
{
\node {8}; \&[2mm] \node{1}; \&[-1mm] \node {6}; \\
\node {3}; \&
\node{5}; \&
\node {7}; \\
\node {4}; \&
\node{9}; \&
\node {2}; \\
}
\end{tikzpicture}
\begin{tikzpicture}[every node/.style=draw]
\pgfsetmatrixcolumnsep{1mm}
\pgfmatrix{rectangle}{center}{mymatrix}
{\pgfusepath{}}{\pgfpointorigin}{\let\&=\pgfmatrixnextcell}
{
\node {8}; \&[2mm] \node(a){1}; \&[1cm,between origins] \node(b){6}; \\
\node {3}; \&
\node
{5}; \&
\node
{7}; \\
\node {4}; \&
\node
{9}; \&
\node
{2}; \\
}
\draw [<->,red,thick,every node/.style=] (a.center) -- (b.center)
node [above,midway] {11mm};
\end{tikzpicture}
\begin{tikzpicture}[every node/.style=draw]
\pgfsetmatrixcolumnsep{1cm,between origins}
\pgfmatrix{rectangle}{center}{mymatrix}
{\pgfusepath{}}{\pgfpointorigin}{\let\&=\pgfmatrixnextcell}
{
\node (a) {8}; \& \node (b) {1}; \&[between borders] \node (c) {6}; \\
\node
{3}; \& \node
{5}; \&
\node
{7}; \\
\node
{4}; \& \node
{9}; \&
\node
{2}; \\
}
\begin{scope}[every node/.style=]
\draw [<->,red,thick] (a.center) -- (b.center) node [above,midway] {10mm};
\draw [<->,red,thick] (b.east) -- (c.west) node [above,midway]
{10mm};
\end{scope}
\end{tikzpicture}
The mechanism for the between-row-spacing is the same, only the commands are called differently.
\pgfsetmatrixrowsep{hsep listi}
This macro sets the default separation list for rows.
\pgfmatrixendrow[hadditional sep listi]
This command ends a line. The optional hadditional sep listi is used to determine the spacing between
the row being ended and the next row. The modes and the computation of d is done in the same way
as for columns. For the last row the optional argument has no effect.
Inside matrices (and only there) the command \\ is set up to mean the same as this command.
1043
102.5
Callbacks
There are three macros that get called at the beginning and end of cells. By redefining these macros, which
are empty by default, you can change the appearance of cells in a very general manner.
\pgfmatrixemptycode
This macro is executed for empty cells. This means that pgf uses some macro magic to determine
whether a cell is empty (it immediately ends with \pgfmatrixemptycode or \pgfmatrixendrow) and,
if so, put this macro inside the cell.
empty b
a
empty
c
d empty
\begin{tikzpicture}
\def\pgfmatrixemptycode{\node{empty};}
\pgfmatrix{rectangle}{center}{mymatrix}
{\pgfusepath{}}{\pgfpointorigin}{\let\&=\pgfmatrixnextcell}
{
\node {a}; \&
\& \node {b}; \\
\& \node{c}; \& \node {d}; \& \\
}
\end{tikzpicture}
As can be seen, the macro is not executed for empty cells at the end of row when columns are added
only later on.
\pgfmatrixbegincode
This macro is executed at the beginning of non-empty cells. Correspondingly, \pgfmatrixendcode is
added at the end of every non-empty cell.
a b c
e
d
\begin{tikzpicture}
\def\pgfmatrixbegincode{\node[draw]\bgroup}
\def\pgfmatrixendcode{\egroup;}
\pgfmatrix{rectangle}{center}{mymatrix}
{\pgfusepath{}}{\pgfpointorigin}{\let\&=\pgfmatrixnextcell}
{
a \& b \& c \\
d \&
\& e \\
}
\end{tikzpicture}
Note that between \pgfmatrixbegincode and \pgfmatrixendcode there will not only be the contents
of the cell. Rather, pgf will add some (invisible) commands for book-keeping purposes that involve
\let and \gdef. In particular, it is not a good idea to have \pgfmatrixbegincode end with \csname
and \pgfmatrixendcode start with \endcsname.
\pgfmatrixendcode
See the explanation above.
The following two counters allow you to access the current row and current column in a callback:
\pgfmatrixcurrentrow
This counter stores the current row of the current cell of the matrix. Do not even think about changing
this counter.
\pgfmatrixcurrentcolumn
This counter stores the current column of the current cell of the matrix.
1044
103
Coordinate, Canvas, and Nonlinear Transformations
103.1
Overview
pgf offers different ways of scaling, shifting, and rotating (these operations are generally known as transformations) graphics: You can apply coordinate transformations to all coordinates, you can apply canvas
transformations to the canvas on which you draw, and you can apply additional nonlinear transformations.
(The names “coordinate” and “canvas” transformations are not standard, I introduce them only for the
purposes of this manual.)
The differences are the following:
• As the name “coordinate transformation” suggests, coordinate transformations apply only to coordinates. For example, when you specify a coordinate like \pgfpoint{1cm}{2cm} and you wish to
“use” this coordinate—for example as an argument to a \pgfpathmoveto command—then the coordinate transformation matrix is applied to the coordinate, resulting in a new coordinate. Continuing
the example, if the current coordinate transformation is “scale by a factor of two,” the coordinate
\pgfpoint{1cm}{2cm} actually designates the point (2cm, 4cm).
Note that coordinate transformations apply only to coordinates. They do not apply to, say, line width
or shadings or text.
• The effect of a “canvas transformation” like “scale by a factor of two” can be imagined as follows: You
first draw your picture on a “rubber canvas” normally. Then, once you are done, the whole canvas is
transformed, in this case stretched by a factor of two. In the resulting image everything will be larger:
Text, lines, coordinates, and shadings.
• Nonlinear transformations are a special form of coordinate transformations that are, as the name suggests, not linear. The support for nonlinear transformations is quite different from the support for
linear coordinate transformations, the main reason being speed: While linear coordinate transformations can be applied very quickly (pgf does so almost constantly), nonlinear transformations are much
harder to apply and also to use. For this reason, nonlinear transformations are implemented in a
special module nonlineartransformations that has to be loaded explicitly. By default, they are not
available.
In many cases, it is preferable that you use coordinate transformations and not canvas transformations.
When canvas transformations are used, pgf looses track of the coordinates of nodes and shapes. Also, canvas
transformations often cause undesirable effects like changing text size. For these reasons, pgf makes it easy
to setup the coordinate transformation, but a bit harder to change the canvas transformation. Because of
the speed penalties caused by nonlinear transformations, they are even harder to set up.
103.2
Coordinate Transformations
103.2.1
How PGF Keeps Track of the Coordinate Transformation Matrix
pgf has an internal coordinate transformation matrix. This matrix is applied to coordinates “in certain
situations.” This means that the matrix is not always applied to every coordinate “no matter what.” Rather,
pgf tries to be reasonably smart at when and how this matrix should be applied. The most prominent
examples are the path construction commands, which apply the coordinate transformation matrix to their
inputs.
The coordinate transformation matrix consists of four numbers a, b, c, and d, and two dimensions s
and t. When the coordinate transformation matrix is applied to a coordinate (x, y), the new coordinate
(ax + by + s, cx + dy + t) results. For more details on how transformation matrices work in general, please
see, for example, the pdf or PostScript reference or a textbook on computer graphics.
The coordinate transformation matrix is equal to the identity matrix at the beginning. More precisely,
a = 1, b = 0, c = 0, d = 1, s = 0pt, and t = 0pt.
The different coordinate transformation commands will modify the matrix by concatenating it with
another transformation matrix. This way the effect of applying several transformation commands will
accumulate.
The coordinate transformation matrix is local to the current TEX group (unlike the canvas transformation
matrix, which is local to the current {pgfscope}). Thus, the effect of adding a coordinate transformation
to the coordinate transformation matrix will last only till the end of the current TEX group.
1045
103.2.2
Commands for Relative Coordinate Transformations
The following commands add a basic coordinate transformation to the current coordinate transformation
matrix. For all commands, the transformation is applied in addition to any previous coordinate transformations.
\pgftransformshift{hpointi}
Shifts coordinates by hpointi.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (2,1) -- (1,0);
\pgftransformshift{\pgfpoint{1cm}{1cm}}
\draw[red] (0,0) -- (2,1) -- (1,0);
\end{tikzpicture}
\pgftransformxshift{hdimensionsi}
Shifts coordinates by hdimensioni along the x-axis.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (2,1) -- (1,0);
\pgftransformxshift{.5cm}
\draw[red] (0,0) -- (2,1) -- (1,0);
\end{tikzpicture}
\pgftransformyshift{hdimensionsi}
Like \pgftransformxshift, only for the y-axis.
\pgftransformscale{hfactor i}
Scales coordinates by hfactor i.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (2,1) -- (1,0);
\pgftransformscale{.75}
\draw[red] (0,0) -- (2,1) -- (1,0);
\end{tikzpicture}
\pgftransformxscale{hfactor i}
Scales coordinates by hfactor i in the x-direction.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (2,1) -- (1,0);
\pgftransformxscale{.75}
\draw[red] (0,0) -- (2,1) -- (1,0);
\end{tikzpicture}
\pgftransformyscale{hfactor i}
Like \pgftransformxscale, only for the y-axis.
\pgftransformxslant{hfactor i}
Slants coordinates by hfactor i in the x-direction. Here, a factor of 1 means 45◦ .
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (2,1) -- (1,0);
\pgftransformxslant{.5}
\draw[red] (0,0) -- (2,1) -- (1,0);
\end{tikzpicture}
1046
\pgftransformyslant{hfactor i}
Slants coordinates by hfactor i in the y-direction.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (2,1) -- (1,0);
\pgftransformyslant{-1}
\draw[red] (0,0) -- (2,1) -- (1,0);
\end{tikzpicture}
\pgftransformrotate{hanglesi}
Rotates coordinates counterclockwise by hanglesi given in degrees.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (2,1) -- (1,0);
\pgftransformrotate{30}
\draw[red] (0,0) -- (2,1) -- (1,0);
\end{tikzpicture}
\pgftransformtriangle{hai}{hbi}{hci}
This command transforms the coordinate system in such a way that the triangle given by the points
hai, hbi and hci lies at the coordinates (0, 0), (1pt, 0pt) and (0pt, 1pt).
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgftransformtriangle
{\pgfpoint{1cm}{0cm}}
{\pgfpoint{0cm}{2cm}}
{\pgfpoint{3cm}{1cm}}
\draw (0,0) -- (1pt,0pt) -- (0pt,1pt) -- cycle;
\end{tikzpicture}
\pgftransformcm{hai}{hbi}{hci}{hd i}{hpointi}
Applies the transformation matrix given by a, b, c, and d and the shift hpointi to coordinates (in addition
to any previous transformations already in force).
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (2,1) -- (1,0);
\pgftransformcm{1}{1}{0}{1}{\pgfpoint{.25cm}{.25cm}}
\draw[red] (0,0) -- (2,1) -- (1,0);
\end{tikzpicture}
\pgftransformarrow{hstarti}{hend i}
Shifts coordinates to the end of the line going from hstarti to hend i with the correct rotation.
tip
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (3,1);
\pgftransformarrow{\pgfpointorigin}{\pgfpoint{3cm}{1cm}}
\pgftext{tip}
\end{tikzpicture}
1047
\pgftransformlineattime{htimei}{hstarti}{hend i}
Shifts coordinates by a specific point on a line at a specific time. The point by which the coordinate is
shifted is calculated by calling \pgfpointlineattime, see Section 96.5.2.
In addition to shifting the coordinate, a rotation may also be applied. Whether this is the case depends
on whether the TEX if \ifpgfslopedattime is set to true or not.
Hi!
Hi!
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (2,1);
\pgftransformlineattime{.25}{\pgfpointorigin}{\pgfpoint{2cm}{1cm}}
\pgftext{Hi!}
\end{tikzpicture}
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) -- (2,1);
\pgfslopedattimetrue
\pgftransformlineattime{.25}{\pgfpointorigin}{\pgfpoint{2cm}{1cm}}
\pgftext{Hi!}
\end{tikzpicture}
If \ifpgfslopedattime is true, another TEX \if is important: \ifpgfallowupsidedowattime. If this
is false, pgf will ensure that the rotation is done in such a way that text is never “upside down.”
There is another TEX \if that influences this command. If you set \ifpgfresetnontranslationattime to true, then, between shifting the coordinate and (possibly) rotating/sloping the coordinate, the
command \pgftransformresetnontranslations is called. See the description of this command for
details.
Hi!
Hi!
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgftransformscale{1.5}
\draw
(0,0) -- (2,1);
\pgfslopedattimetrue
\pgfresetnontranslationattimefalse
\pgftransformlineattime{.25}{\pgfpointorigin}{\pgfpoint{2cm}{1cm}}
\pgftext{Hi!}
\end{tikzpicture}
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgftransformscale{1.5}
\draw
(0,0) -- (2,1);
\pgfslopedattimetrue
\pgfresetnontranslationattimetrue
\pgftransformlineattime{.25}{\pgfpointorigin}{\pgfpoint{2cm}{1cm}}
\pgftext{Hi!}
\end{tikzpicture}
\pgftransformcurveattime{htimei}{hstarti}{hfirst supporti}{hsecond supporti}{hend i}
Shifts coordinates by a specific point on a curve at a specific time, see Section 96.5.2 once more.
As for the line-at-time transformation command, \ifpgfslopedattime decides whether an additional
rotation should be applied. Again, the value of \ifpgfallowupsidedowattime is also considered.
Hi!
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) .. controls (0,2) and (1,2) .. (2,1);
\pgftransformcurveattime{.25}{\pgfpointorigin}
{\pgfpoint{0cm}{2cm}}{\pgfpoint{1cm}{2cm}}{\pgfpoint{2cm}{1cm}}
\pgftext{Hi!}
\end{tikzpicture}
1048
Hi!
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\draw
(0,0) .. controls (0,2) and (1,2) .. (2,1);
\pgfslopedattimetrue
\pgftransformcurveattime{.25}{\pgfpointorigin}
{\pgfpoint{0cm}{2cm}}{\pgfpoint{1cm}{2cm}}{\pgfpoint{2cm}{1cm}}
\pgftext{Hi!}
\end{tikzpicture}
The value of \ifpgfresetnontranslationsattime is also taken into account.
\pgftransformarcaxesattime{htime ti}{hcenter i}{h0-degree axisi}{h90-degree axisi}{hstart
anglei}{hend anglei}
Shifts coordinates by a specific point on an arc at a specific time, see Section 96.5.2 once more.
As for the previous commands, \ifpgfslopedattime decides whether an additional rotation should be
applied and \ifpgfallowupsidedowattime is also considered.
Hi!
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfpathmoveto{\pgfpoint{2cm}{1cm}}
\pgfpatharcaxes{0}{60}{\pgfpoint{2cm}{0cm}}{\pgfpoint{0cm}{1cm}}
\pgfusepath{stroke}
\pgfslopedattimetrue
\pgftransformarcaxesattime{.25}
{\pgfpoint{0cm}{1cm}}
{\pgfpoint{2cm}{0cm}}{\pgfpoint{0cm}{1cm}}
{0}{60}
\pgftext{Hi!}
\end{tikzpicture}
The value of \ifpgfresetnontranslationsattime is also taken into account.
\ifpgfslopedattime
Decides whether the “at time” transformation commands also rotate coordinates or not.
\ifpgfallowupsidedowattime
Decides whether the “at time” transformation commands should allow the rotation be done in such a
way that “upside-down text” can result.
\ifpgfresetnontranslationsattime
Decides whether the “at time” transformation commands should reset the non-translations between
shifting and rotating.
103.2.3
Commands for Absolute Coordinate Transformations
The coordinate transformation commands introduced up to now are always applied in addition to any
previous transformations. In contrast, the commands presented in the following can be used to change the
transformation matrix “in absolute terms.” Note that this is, in general, dangerous and will often produce
unexpected effects. You should use these commands only if you really know what you are doing.
\pgftransformreset
Resets the coordinate transformation matrix to the identity matrix. Thus, once this command is given
no transformations are applied till the end of the scope.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgftransformrotate{30}
\draw
(0,0) -- (2,1) -- (1,0);
\pgftransformreset
\draw[red] (0,0) -- (2,1) -- (1,0);
\end{tikzpicture}
\pgftransformresetnontranslations
1049
This command sets the a, b, c, and d part of the coordinate transformation matrix to a = 1, b = 0,
c = 0, and d = 1. However, the current shifting of the matrix is not modified.
The effect of this command is that any rotation/scaling/slanting is undone in the current TEX group,
but the origin is not “moved back.”
This command is mostly useful directly before a \pgftext command to ensure that the text is not
scaled or rotated.
ed
t
a
rot
shifted only
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgftransformscale{2}
\pgftransformrotate{30}
\pgftransformxshift{1cm}
{\color{red}\pgftext{rotated}}
\pgftransformresetnontranslations
\pgftext{shifted only}
\end{tikzpicture}
\pgftransforminvert
Replaces the coordinate transformation matrix by a coordinate transformation matrix that “exactly
undoes the original transformation.” For example, if the original transformation was “scale by 2 and
then shift right by 1cm” the new one is “shift left by 1cm and then scale by 1/2.”
This command will produce an error if the determinant of the matrix is too small, that is, if the matrix
is near-singular.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgftransformrotate{30}
\draw
(0,0) -- (2,1) -- (1,0);
\pgftransforminvert
\draw[red] (0,0) -- (2,1) -- (1,0);
\end{tikzpicture}
103.2.4
Saving and Restoring the Coordinate Transformation Matrix
There are two commands for saving and restoring coordinate transformation matrices.
\pgfgettransform{hmacroi}
This command will (locally) define hmacroi to a representation of the current coordinate transformation
matrix. This matrix can later on be reinstalled using \pgfsettransform.
\pgfsettransform{hmacroi}
Reinstalls a coordinate transformation matrix that was previously saved using \pgfgettransform.
\pgfgettransformentries{hmacro for ai}{hmacro for bi}{hmacro for ci}{hmacro for d i}{hmacro for
shift x i}{hmacro for shift yi}
This command is similar to \pgfgettransform except that it stores the current coordinate transformation matrix in a set of six macros.
The matrix can later on be reinstalled using \pgfsettransformentries. Furthermore, all these macros
(or just a few of them) can be used as arguments for \pgftransformcm.
\pgfsettransformentries{hai}{hbi}{hci}{hd i}{hshiftx i}{hshiftyi}
Reinstalls a coordinate transformation matrix that was previously saved using the storage command \pgfgettransformentries. This command can also be used to replace any previously existing coordinate transformation matrix (it is thus equivalent to \pgftransformreset followed by
\pgftransformcm).
1050
103.2.5
Computing Adjustments for Coordinate Transformations
\pgftransformationadjustments
This command computes “adjustments” for the current transformation matrix so that even when you
install a transformation matrix that scales everything by a certain factor, you can still draw something of
“an absolute size.” Suppose for instance that you install a transformation matrix that scales everything
by a factor of 4 and you now wish to draw a horizontal line of length 1cm. Then, if you do not reset
the transformation matrix, you can draw a line of logical length 2.5mm, which will then get scaled to
a line of 1cm. Things get more difficult in case you scale things only, say, vertically. In this case, the
adjustement necessary for horizontal lines is different from the one needed for vertical lines.
This function computes two scaling factors, one for horizontal lines and one for vertical lines, and stores
them in the following macros:
\pgfhorizontaltransformationadjustment
When you scale the length of a horizontal line by this factor in the current transformation, you
compensate for the scaling. Formally, it is 1/ktransform(1, 0)k2 , where transform applies the current
transformations matrix to the given number.
\begin{tikzpicture}
\draw [help lines] (0,0) grid (2,2);
\begin{scope}[xscale=2,thick]
\draw [red] (1,1) -- ++(1,0);
\pgftransformationadjustments
\draw [blue] (1,0) -- ++(\pgfhorizontaltransformationadjustment,0);
\end{scope}
\end{tikzpicture}
\begin{tikzpicture}
\draw [help lines] (0,0) grid (2,2);
\begin{scope}[xscale=2,thick,rotate=90]
\draw [red] (1,1) -- ++(1,0);
\pgftransformationadjustments
\draw [blue] (1,0) -- ++(\pgfhorizontaltransformationadjustment,0);
\end{scope}
\end{tikzpicture}
\pgfverticaltransformationadjustment
1/ktransform(0, 1)k2 .
Note that the “right” way to draw a line of absolute length 1cm in a transformed coordinate system
is to first compute the start point and to then reset the transformation matrix. The transformation
adjustments computed here are important only in situations where you cannot do this, for instance
when an outer xsep must be set.
103.3
Canvas Transformations
The canvas transformation matrix is not managed by pgf, but by the output format like pdf or PostScript.
All that pgf does is to call appropriate low-level \pgfsys@ commands to change the canvas transformation
matrix.
Unlike coordinate transformations, canvas transformations apply to “everything,” including images, text,
shadings, line thickness, and so on. The idea is that a canvas transformation really stretches and deforms
the canvas after the graphic is finished.
Unlike coordinate transformations, canvas transformations are local to the current {pgfscope}, not to
the current TEX group. This is due to the fact that they are managed by the backend driver, not by TEX or
pgf.
Unlike the coordinate transformation matrix, it is not possible to “reset” the canvas transformation
matrix. The only way to change it is to concatenate it with another canvas transformation matrix or to end
the current {pgfscope}.
Unlike coordinate transformations, pgf does not “keep track” of canvas transformations. In particular, it
will not be able to correctly save the coordinates of shapes or nodes when a canvas transformation is used.
1051
pgf does not offer a whole set of special commands for modifying the canvas transformation matrix.
Instead, different commands allow you to concatenate the canvas transformation matrix with a coordinate
transformation matrix (and there are numerous commands for specifying a coordinate transformation, see
the previous section).
\pgflowlevelsynccm
This command concatenates the canvas transformation matrix with the current coordinate transformation matrix. Afterward, the coordinate transformation matrix is reset.
The effect of this command is to “synchronize” the coordinate transformation matrix and the canvas
transformation matrix. All transformations that were previously applied by the coordinate transformations matrix are now applied by the canvas transformation matrix.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfsetlinewidth{1pt}
\pgftransformscale{5}
\draw
(0,0) -- (0.4,.2);
\pgftransformxshift{0.2cm}
\pgflowlevelsynccm
\draw[red] (0,0) -- (0.4,.2);
\end{tikzpicture}
\pgflowlevel{htransformation codei}
This command concatenates the canvas transformation matrix with the coordinate transformation specified by htransformation codei.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfsetlinewidth{1pt}
\pgflowlevel{\pgftransformscale{5}}
\draw
(0,0) -- (0.4,.2);
\end{tikzpicture}
\pgflowlevelobj{htransformation codei}{hcodei}
This command creates a local {pgfscope}. Inside this scope, \pgflowlevel is first called with the
argument htransformation codei, then the hcodei is inserted.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfsetlinewidth{1pt}
\pgflowlevelobj{\pgftransformscale{5}}
{\draw (0,0) -- (0.4,.2);}
\pgflowlevelobj{\pgftransformxshift{-1cm}}{\draw (0,0) -- (0.4,.2);}
\end{tikzpicture}
\begin{pgflowlevelscope}{htransformation codei}
henvironment contentsi
\end{pgflowlevelscope}
This environment first surrounds the henvironment contentsi by a {pgfscope}.
\pgflowlevel with the argument htransformation codei.
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfsetlinewidth{1pt}
\begin{pgflowlevelscope}{\pgftransformscale{5}}
\draw (0,0) -- (0.4,.2);
\end{pgflowlevelscope}
\begin{pgflowlevelscope}{\pgftransformxshift{-1cm}}
\draw (0,0) -- (0.4,.2);
\end{pgflowlevelscope}
\end{tikzpicture}
\pgflowlevelscope{htransformation codei}
1052
Then it calls
henvironment contentsi
\endpgflowlevelscope
Plain TEX version of the environment.
\startpgflowlevelscope{htransformation codei}
henvironment contentsi
\stoppgflowlevelscope
ConTEXt version of the environment.
103.4
Nonlinear Transformations
In order to use nonlinear transformations, you first have to load the following pgf module:
\usepgfmodule{nonlineartransformations}
\usepgfmodule[nonlineartransformations]
% LATEX and plain TEX and pure pgf
% ConTEXt and pure pgf
Loads the necessary functionality for nonlinear transformations.
103.4.1
Introduction
The difference between the coordinate transformations introduced in Section 103.2 above to nonlinear transformations is, of course, that the transformations can be nonlinear. An example of a nonlinear transformation
is the transformation underlying polar coordinates: A polar coordinate (r, d) gets transformed to the canvas
position (d cos r, d sin r), which is clearly not a linear transformation.
Nonlinear transformations work somewhat like the normal linear coordinate transformations in the sense
that they apply to coordinate and thereby to the construction of paths, but not to things like text or line
width or shadings. (Indeed, it is not possible to apply nonlinear transformations to, say, text.)
This means that there is a fundamental difference between, on the one hand, calling a function like
\pgfpointpolar or specifying a coordinate as (45:2) in Tik Z and, on the other hand, installing the nonlinear
transformation “polar coordinates” using the command \pgftransformnonlinear: In a coordinate like
(45:2) the user explicitly says “please evaluate this one coordinate in polar coordinate and then continue
in the normal coordinate system with the result.” Otherwise nothing changes and a line between two points
specified in this way is still a straight line.
Things are quite different when we install a polar transformation using \pgftransformnonlinear. Now,
even a seemingly low-level Cartesian coordinate \pgfqpoint{1pt}{1pt} will get transformed. Even more
drastically, what is specified as a straight line like
\draw (0,1) -- (1,1);
can become curved since everything gets transformed.
103.4.2
Installing Nonlinear Transformation
\pgftransformnonlinear{htransformation codei}
This command adds the htransformation codei to the list of non-linear transformations currently in
force. Thus, similar to linear coordinate transformations, each additional call to this function adds
another transformation to the current TEX scope and the effect ends at the end of the current scope.
In practice, however, you typically will not have more than one active nonlinear transformation.
The job of the htransformation codei is to map a point p given in the registers \pgf@x and \pgf@y to a
new coordinate f (p), which should be returned in \pgf@x and \pgf@y as well. As an example, suppose
we wish to install polar coordinates as the nonlinear transformation. For this, we need a bit of code:
\def\polartransformation{%
% \pgf@x will contain the radius
% \pgf@y will contain the distance
\pgfmathsincos@{\pgf@sys@tonumber\pgf@x}%
% pgfmathresultx is now the cosine of radius and
% pgfmathresulty is the sine of radius
\pgf@x=\pgfmathresultx\pgf@y%
\pgf@y=\pgfmathresulty\pgf@y%
}
1053
(In case you wonder why you cannot just call \pgfpointpolar at this point: You can, but this function
internally uses \pgf@x and \pgf@y in complicated ways, so you would first have to safe them so some
other registers. Also, the above is faster.)
If we were to call this function again, we would get something funny like “polar-polar coordinates,” so
let’s not do this. Let us instead have a look at the effect this call has: Once a nonlinear transformation is
installed, all subsequent path constructions are affected by this transformation. In particular, a normal
grid now becomes the typical “polar grid.”
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
% Start nonlinear transformation
\pgftransformnonlinear{\polartransformation}% see above
% Draw something with this transformation in force
\draw (0pt,0mm) grid [xstep=10pt, ystep=5mm] (90pt, 20mm);
\end{tikzpicture}
103.4.3
Applying Nonlinear Transformations to Points
\pgfpointtransformednonlinear{hpointi}
Works like \pgfpointtransformed, but also applies the current nonlinear transformation; that is, it
first applies the current linear transformation and then the current nonlinear transformations. Note
that, just like \pgfpointtransformed, you normally do not call this function directly since it is called
internally by the path drawing commands.
103.4.4
Applying Nonlinear Transformations to Paths
When a nonlinear transformation is installed, the normal path construction commands like \pgfpathmoveto
get adjusted so that the “honour” the nonlinear transformations currently in force. For \pgfpathmoveto
this is pretty simple: Instead of just applying the linear transformation matrix to the point to which
the path should “jump” next, we also apply the nonlinear transformation. However, for a command like
\pgfpathlineto, things are much more difficult: A straight line will no longer be a straight line!
In order to make straight lines “bend”, the following changes are in force while a nonlinear transformation
is installed:
1. Whenever a straight line between two points p and q should be added to the path, either through
\pgfpathlineto or through \pgfpathclose, we replace this straight line by a “degenerated curve”
from p to q whose control points are at one third and two third of the distance between p and q on
the line between p and q. In this way, while nonlinear transformations are in force, we only need to
transform curves.
2. Next, suppose we wish to transform a curve from p to q with supports s and t. For this, we simply
apply the nonlinear transformation f to all four points and draw a line with the results. Note that
this mapping is actually not quite satisfactory for long lines that are strongly curved:
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
{
\pgftransformnonlinear{\polartransformation}
% The curve with the controls computed by pgf: a nice quarter arc
\draw [red] (0,20mm) -- (90pt,20mm);
}
% Here is the curve with controls just transformed:
\draw (0:20mm) .. controls (30pt:20mm) and (60pt:20mm) .. (90pt:20mm);
\end{tikzpicture}
As the example shows, the control points now lie on the arc; but in reality they should point along the
tangents at the start and the end. This is exactly when pgf does through the computation described
above.
3. To overcome the effect of the control points being “off,” it is necessary to split up longer curves into
smaller parts, which are drawn individually to increase the accuracy. When such splitting occurs, can
be configured using the following command:
1054
\pgfsettransformnonlinearflatness{hdimensioni} (initially 5pt)
Whenever in a to-be-drawn curve the L∞ -distance (maximum of the distances in x- and
y-directions) between the start of a curve and its first control point or between the first and
second control points or between the second control point and the end is more than hdistancei,
the curve gets split in the middle (more precisely, at time t = 0.5) and we draw the two parts
individually (for them, splitting may occur again, if the curve is still too long).
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\draw[red] (0:20mm) arc [start angle=0, end angle=90, radius=2cm];
{
\pgftransformnonlinear{\polartransformation}
\pgfsettransformnonlinearflatness{2pt} % very precise
\draw (0,20mm) -- (90pt,20mm);
}
\end{tikzpicture}
103.4.5
Applying Nonlinear Transformations to Text
Earlier, it was pointed that nonlinear transformations do not apply to text. Nevertheless, when you use
\pgftext or \pgfnode, pgf will do a sort of “best effort” to render the text in the nonlinear coordinate
system: The point where the text should be shown can obviously be computed easily. When then temporarily
reset the nonlinear transformation and, instead, setup a linear transformation that matches the nonlinear
transformation at the point where the text should be. Then, the text is shown. This means that if the text is
longer, it will not “follow” the nonlinear transformation, but near the origin of the text it will look “correct.”
As an example, let us add some text at the grid point of the above example:
◦
09
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\pgftransformnonlinear{\polartransformation}% see above
◦
06
◦ 03
◦
09 0◦6
◦ 03
% Draw something with this transformation in force
\draw (0pt,0mm) grid [xstep=10pt, ystep=5mm] (90pt, 20mm);
0
◦
0
◦
\foreach \angle in {0,30,60,90}
\foreach \dist in {1,2}
{
\pgftransformshift{\pgfpoint{\angle pt}{\dist cm}}
\pgftext{\angle$^\circ$}
}
\end{tikzpicture}
103.4.6
Approximating Nonlinear Transformations Using Linear Transformations
At any given point, the current nonlinear transformation can be approximated using a linear transformation.
The following two functions allow you to install such a local approximation:
\pgfapproximatenonlineartransformation
This command will do two things:
1. It clears the nonlinear transformations for the rest of the current TEX scope, so only linear transformations apply.
2. However, before removing the nonlinear transformations, the linear transformation matrix is modified so that it mimics the effect the nonlinear transformation had at the origin. That is, after you
call this command, drawing something near the origin will look almost the same as if you had not
called it.
1055
oo
f
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\pgftransformnonlinear{\polartransformation}% see above
\draw (0pt,0mm) grid [xstep=10pt, ystep=5mm] (90pt, 20mm);
\begin{scope}[shift={(45pt,20mm)}]
% Draw something near "origin":
\draw [red] (-10pt,-10pt) -- (10pt,10pt);
\draw [red] (10pt,-10pt) -- (-10pt,10pt);
% Now draw the same, but in the "approximate" coordinate system:
\pgfapproximatenonlineartransformation
\draw [] (-10pt,-10pt) -- (10pt,10pt);
\draw [] (10pt,-10pt) -- (-10pt,10pt);
\pgftext{foo};
\end{scope}
\end{tikzpicture}
This command is used by \pgftext and \pgfnode to transform text when a nonlinear transformation
is in force.
\pgfapproximatenonlineartranslation
This command works like the normal approximation command, but it will only approximate how the
origin gets translated, it will not approximate the rotation, skewing, or scaling that is involved. This is
useful for drawing text at the right position, but without “mutilating” the text.
foo
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
\pgftransformnonlinear{\polartransformation}% see above
\draw (0pt,0mm) grid [xstep=10pt, ystep=5mm] (90pt, 20mm);
\begin{scope}[shift={(45pt,20mm)}]
% Draw something near "origin":
\draw [red] (-10pt,-10pt) -- (10pt,10pt);
\draw [red] (10pt,-10pt) -- (-10pt,10pt);
% Now draw the same, but in the "approximate" coordinate system:
\pgfapproximatenonlineartranslation
\draw [] (-10pt,-10pt) -- (10pt,10pt);
\draw [] (10pt,-10pt) -- (-10pt,10pt);
\pgftext{foo};
\end{scope}
\end{tikzpicture}
103.4.7
Nonlinear Transformation Libraries
Tik Z Library curvilinear
\usepgflibrary{curvilinear}
\usepgflibrary[curvilinear]
\usetikzlibrary{curvilinear}
\usetikzlibrary[curvilinear]
%
%
%
%
LATEX and plain TEX and pure pgf
ConTEXt and pure pgf
LATEX and plain TEX when using Tik Z
ConTEXt when using Tik Z
This library defines commands for computing nonlinear transformations “along Bézier curves”.
Up to now, our running example for a nonlinear transformation was polar transformation. However, is
pgf nonlinear transformations are actually mainly used for transforming arrow tips; and these need to be
transformed “along curves.” The curvilinear library defines a number of commands that offer the necessary
computations for such transformations.
\pgfsetcurvilinearbeziercurve{hstarti}{hfirst supporti}{hsecond supporti}{hend i}
Prior to using any other command from this library, you first call this function to “install” a Bézier
curve to which the commands will refer. This curve will be local to the current TEX scope and you can
install only one curve at a time.
The main job of this command is to store the passed points internally and to build a lookup table for
distance-to-time conversions, see the next command.
1056
\pgfsetcurvilinearbeziercurve
{\pgfpointorigin}
{\pgfpoint{1cm}{1cm}}
{\pgfpoint{2cm}{1cm}}
{\pgfpoint{3cm}{0cm}}
\pgfcurvilineardistancetotime{hdistancei}
This command does a “distance-to-time-conversion”: It tries to compute a time t, returned in \pgf@x,
that corresponds to travelling hdistancei along the curve that has last been installed using the command
\pgfsetcurvilinearbeziercurve. The distance-to-time-conversion uses the precomputations done by
that command. Note that several compromises had to be made between speed and accuracy:
• The conversion will be best near the start of the curve.
• The more “degenerate” the curve, the worse the results.
\pgfpointcurvilinearbezierorthogonal{hdistancei}{hoffseti}
This command computes the following point: Consider the curve last installed using the command
\pgfsetcurvilinearbeziercurve. We travel along this curve by hdistancei, arriving at a point p.
Then, we turn by 90◦ and travel by hoffseti units “aways from the curve,” arriving at a point q. This
point q will now be returned in \pgf@x and \pgf@y; furthermore, the transformed local coordinate
system at point q will also be returned \pgf@xa and the other registers, see \pgftransformnonlinear
for details.
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
{
\pgfsetcurvilinearbeziercurve
{\pgfpoint{0mm}{20mm}}
{\pgfpoint{11mm}{20mm}}
{\pgfpoint{20mm}{11mm}}
{\pgfpoint{20mm}{0mm}}
\pgftransformnonlinear{\pgfpointcurvilinearbezierorthogonal\pgf@x\pgf@y}%
\draw (0,-30pt) grid [step=10pt] (80pt,30pt);
}
\draw[red, very thick]
(0mm,20mm) .. controls (11mm,20mm) and (20mm,11mm) .. (20mm,0mm);
\end{tikzpicture}
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
{
\pgfsetcurvilinearbeziercurve
{\pgfpoint{0mm}{20mm}}
{\pgfpoint{10mm}{20mm}}
{\pgfpoint{10mm}{10mm}}
{\pgfpoint{20mm}{10mm}}
\pgftransformnonlinear{\pgfpointcurvilinearbezierorthogonal\pgf@x\pgf@y}%
\draw (0,-30pt) grid [step=10pt] (80pt,30pt);
}
\draw[red, very thick]
(0mm,20mm) .. controls (10mm,20mm) and (10mm,10mm) .. (20mm,10mm);
\end{tikzpicture}
\pgfpointcurvilinearbezierpolar{hx i}{hyi}
This command is similar to the previous version, but the transformation is different: The idea is that a
line form (0, 0) to (x, 0) gets transformed to the curve from the start of the curve to a point at distance
x along the curve. This is identical to what the “orthogonal” transformation above also does. The
difference is that a line from (0, 0) to (0, y) gets still transformed to an initial segment of the curve of a
◦
length of y, but
p now rotated by 90 . In general, the point p = (x, y) gets transferred to a point that at
distance p = x2 + y 2 along the curve, but rotated by the angle of p relative to the x-axis.
All of these computations mainly have the following effect: Two straight lines from the start of the curve
as in a Straight Barb arrow tip get transformed to an initial segment of the curve whose length is the
length of the two lines, but this segment gets rotated by the angle of the two lines.
1057
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
{
\pgfsetcurvilinearbeziercurve
{\pgfpoint{0mm}{20mm}}
{\pgfpoint{11mm}{20mm}}
{\pgfpoint{20mm}{11mm}}
{\pgfpoint{20mm}{0mm}}
\pgftransformnonlinear{\pgfpointcurvilinearbezierpolar\pgf@x\pgf@y}%
\draw (0,-30pt) grid [step=10pt] (80pt,30pt);
% Add a "barb":
\draw [blue, very thick] (20pt,10pt) -- (0,0) -- (20pt,-10pt);
}
\draw[red, very thick]
(0mm,20mm) .. controls (11mm,20mm) and (20mm,11mm) .. (20mm,0mm);
\end{tikzpicture}
\begin{tikzpicture}
\draw [help lines] (0,0) grid (3,2);
{
\pgfsetcurvilinearbeziercurve
{\pgfpoint{0mm}{20mm}}
{\pgfpoint{10mm}{20mm}}
{\pgfpoint{10mm}{10mm}}
{\pgfpoint{20mm}{10mm}}
\pgftransformnonlinear{\pgfpointcurvilinearbezierpolar\pgf@x\pgf@y}%
\draw (0,-30pt) grid [step=10pt] (80pt,30pt);
% Add a "barb":
\draw [blue, very thick] (20pt,10pt) -- (0,0) -- (20pt,-10pt);
}
\draw[red, very thick]
(0mm,20mm) .. controls (10mm,20mm) and (10mm,10mm) .. (20mm,10mm);
\end{tikzpicture}
1058
104
Patterns
104.1
Overview
There are many ways of filling a path. First, you can fill it using a solid color and this is also the fastest
method. Second, you can also fill it using a shading, which means that the color changes smoothly between
two (or more) different colors. Third, you can fill it using a tiling pattern and it is explained in the following
how this is done.
A tiling pattern can be imagined as a rectangular tile (hence the name) on which a small picture is
painted. There is not a single tile, but (conceptually) an infinite number of tiles, all showing the same
picture, and these tiles are arranged horizontally and vertically to fill the plane. When you use a tiling
pattern to fill a path, what happens is that the path clips out a “window” through which we see part of this
infinite plane.
Patterns come in two versions: inherently colored patterns and form-only patterns. (These are often
called “color patterns” and “uncolored patterns,” but these names are misleading since uncolored patterns
do have a color and the color changes. As I said, the name is misleading. . . ) An inherently colored pattern
is just a colored tile like, say, a red star with a black outline. A form-only pattern can be imagined as a tile
that is a kind of rubber stamp. When this pattern is used, the stamp is used to print copies of the stamp
picture onto the plane, but we can use a different stamp color each time we use a form-only pattern.
pgf provides a special support for patterns. You can declare a pattern and then use it very much like a fill
color. pgf directly maps patterns to the pattern facilities of the underlying graphic languages (PostScript,
pdf, and svg). This means that filling a path using a pattern will be nearly as fast as if you used a uniform
color.
There are a number of pitfalls and restrictions when using patterns. First, once a pattern has been
declared, you cannot change it anymore. In particular, it is not possible to enlarge it or change the line
width. Such flexibility would require that the repeating of the pattern were not done by the graphic language,
but on the pgf level. This would make patterns orders of magnitude slower to produce and to render.
However, pgf does provide a more-or-less successful emulation of “mutable” patterns, although internally, a
new (fixed) instance of a pattern is declared when the parameters of a pattern change.
Second, the phase of patterns is not well-defined, that is, it is not clear where the origin of the “first” tile
is. To be more precise, PostScript and pdf on the one hand and svg on the other hand define the origin
differently. PostScript and pdf define a fixed origin that is independent of where the path lies. This has
the highly desirable effect that if you use the same pattern to fill multiple paths, the outcome is the same
as if you had filled a single path consisting of the union of all these paths. By comparison, svg uses the
upper-left (?) corner of the path to be filled as the origin. However, the svg specification is a bit vague on
this question.
104.2
Declaring a Pattern
Before a pattern can be used, it must be declared. The following command is used for this:
\pgfdeclarepatternformonly[hvariablesi]{hnamei}{hbottom lefti}{htop righti}{htile sizei}{hcodei}
This command declares a new form-only pattern. The hnamei is a name for later reference. The
two parameters hlower lefti and hupper righti must describe a bounding box that is large enough to
encompass the complete tile.
The size of a tile is given by htile sizei, that is, a tile is a rectangle whose lower left corner is the origin
and whose upper right corner is given by htile sizei. This might make you wonder why the second and
third parameters are needed. First, the bounding box might be smaller than the tile size if the tile is
larger than the picture on the tile. Second, the bounding box might be bigger, in which case the picture
will “bleed” over the tile.
The hcodei should be pgf code than can be protocolled. It should not contain any color code.
1059
\pgfdeclarepatternformonly{stars}
{\pgfpointorigin}{\pgfpoint{1cm}{1cm}}
{\pgfpoint{1cm}{1cm}}
{
\pgftransformshift{\pgfpoint{.5cm}{.5cm}}
\pgfpathmoveto{\pgfpointpolar{0}{4mm}}
\pgfpathlineto{\pgfpointpolar{144}{4mm}}
\pgfpathlineto{\pgfpointpolar{288}{4mm}}
\pgfpathlineto{\pgfpointpolar{72}{4mm}}
\pgfpathlineto{\pgfpointpolar{216}{4mm}}
\pgfpathclose%
\pgfusepath{fill}
}
\begin{tikzpicture}
\filldraw[pattern=stars] (0,0)
rectangle (1.5,2);
\filldraw[pattern=stars,pattern color=red]
(1.5,0) rectangle (3,2);
\end{tikzpicture}
The optional argument hvariablesi consists of a comma separated list of macros, registers or keys,
representing the parameters of the pattern that may vary. If a variable is a key, then the full path name
must be used (specifically, it must start with /). As an example, a list might look like the following:
\mymacro,\mydimen,/pgf/my key. Note that macros and keys should be “simple”. They should only
store values in themselves.
The effect of hvariablesi, is the following: Normally, when this argument is empty, once a pattern has
been declared, it becomes “frozen”. This means that it is not possible to enlarge the pattern or change
the line width later on. By specifying hvariablesi, no pattern is actually created. Instead, the arguments
are stored away (so the macros, registers or keys do not have to be defined in advance).
When the fill pattern is set, pgf checks if the pattern has already been created with the hvariablesi
set to their current values (pgf is usually “smart enough” to distinguish between macros, registers and
keys). If so, this already-declared-pattern is used as the fill pattern. If not, a new instance of the pattern
(which will have a unique internal name) is declared using the current values of hvariablesi. These values
are then saved and the fill pattern set accordingly.
The following shows an example of a pattern which varies according to the values of the macro \size,
the key /tikz/radius, and the TEX dimension \thickness.
\pgfdeclarepatternformonly[/tikz/radius,\thickness,\size]{rings}
{\pgfpoint{-0.5*\size}{-0.5*\size}}
{\pgfpoint{0.5*\size}{0.5*\size}}
{\pgfpoint{\size}{\size}}
{
\pgfsetlinewidth{\thickness}
\pgfpathcircle\pgfpointorigin{\pgfkeysvalueof{/tikz/radius}}
\pgfusepath{stroke}
}
\newdimen\thickness
\tikzset{
radius/.initial=4pt,
size/.store in=\size, size=20pt,
thickness/.code={\thickness=#1},
thickness=0.75pt
}
\begin{tikzpicture}[rings/.style={pattern=rings}]
\filldraw [rings, radius=2pt, size=6pt]
(0,0)
rectangle
\filldraw [rings, radius=2pt, size=8pt]
(2,0)
rectangle
\filldraw [rings, radius=6pt, thickness=2pt] (0,2.5) rectangle
\filldraw [rings, radius=8pt, thickness=4pt] (2,2.5) rectangle
\end{tikzpicture}
+(1.5,2);
+(1.5,2);
+(1.5,2);
+(1.5,2);
\pgfdeclarepatterninherentlycolored[hvariablesi] {hnamei} {hlower lefti} {hupper righti} {htile
sizei} {hcodei}
This command works like \pgfdeclarepatternuncolored, only the pattern will have an inherent color.
To set the color, you should use pgf’s color commands, not the \color command, since this fill is not
protocolled.
1060
\pgfdeclarepatterninherentlycolored{green stars}
{\pgfpointorigin}{\pgfpoint{1cm}{1cm}}
{\pgfpoint{1cm}{1cm}}
{
\pgfsetfillcolor{green!50!black}
\pgftransformshift{\pgfpoint{.5cm}{.5cm}}
\pgfpathmoveto{\pgfpointpolar{0}{4mm}}
\pgfpathlineto{\pgfpointpolar{144}{4mm}}
\pgfpathlineto{\pgfpointpolar{288}{4mm}}
\pgfpathlineto{\pgfpointpolar{72}{4mm}}
\pgfpathlineto{\pgfpointpolar{216}{4mm}}
\pgfpathclose%
\pgfusepath{stroke,fill}
}
\begin{tikzpicture}
\filldraw[pattern=green stars] (0,0) rectangle (3,2);
\end{tikzpicture}
104.3
Setting a Pattern
Once a pattern has been declared, it can be used.
\pgfsetfillpattern{hnamei}{hcolor i}
This command specifies that paths that are filled should be filled with the “color” by the pattern hnamei.
For an inherently colored pattern, the hcolor i parameter is ignored. For form-only patterns, the hcolor i
parameter specifies the color to be used for the pattern.
\begin{tikzpicture}
\pgfsetfillpattern{stars}{red}
\filldraw (0,0) rectangle (1.5,2);
\pgfsetfillpattern{green stars}{red}
\filldraw (1.5,0) rectangle (3,2);
\end{tikzpicture}
1061
105
Declaring and Using Images
This section describes the commands for creating images.
105.1
Overview
To be quite frank, LATEX’s \includegraphics is designed better than pgf’s image mechanism. For this
reason, I recommend that you use the standard image inclusion mechanism of your format. Thus, LATEX
users are encouraged to use \includegraphics to include images.
However, there are reasons why you might need to use the image inclusion facilities of pgf:
• There is no standard image inclusion mechanism in your format. For example, plain TEX does not
have one, so pgf’s inclusion mechanism is “better than nothing.”
However, this applies only to the pdftex backend. For all other backends, pgf currently maps its
commands back to the graphicx package. Thus, in plain TEX, this does not really help. It might be
a good idea to fix this in the future such that pgf becomes independent of LATEX, thereby providing
a uniform image abstraction for all formats.
• You wish to use masking. This is a feature that is only supported by pgf, though I hope that someone
will implement this also for the graphics package in LATEX in the future.
Whatever your choice, you can still use the usual image inclusion facilities of the graphics package.
The general approach taken by pgf to including an image is the following: First, \pgfdeclareimage
declares the image. This must be done prior to the first use of the image. Once you have declared an image,
you can insert it into the text using \pgfuseimage. The advantage of this two-phase approach is that, at
least for pdf, the image data will only be included once in the file. This can drastically reduce the file size if
you use an image repeatedly, for example in an overlay. However, there is also a command called \pgfimage
that declares and then immediately uses the image.
To speedup the compilation, you may wish to use the following class option:
\usepackage[draft]{pgf}
In draft mode boxes showing the image name replace the images. It is checked whether the image files
exist, but they are not read. If either height or width is not given, 1cm is used instead.
105.2
Declaring an Image
\pgfdeclareimage[hoptionsi]{himage namei}{hfilenamei}
Declares an image, but does not paint anything. To draw the image, use \pgfuseimage{himage namei}.
The hfilenamei may not have an extension. For pdf, the extensions .pdf, .jpg, and .png will automatically tried. For PostScript, the extensions .eps, .epsi, and .ps will be tried.
The following options are possible:
• height=hdimensioni sets the height of the image. If the width is not specified simultaneously, the
aspect ratio of the image is kept.
• width=hdimensioni sets the width of the image. If the height is not specified simultaneously, the
aspect ratio of the image is kept.
• page=hpage number i selects a given page number from a multipage document. Specifying this
option will have the following effect: first, pgf tries to find a file named
hfilenamei.pagehpage number i.hextensioni
If such a file is found, it will be used instead of the originally specified filename. If not, pgf inserts
the image stored in hfilenamei.hextensioni and if a recent version of pdflatex is used, only the
selected page is inserted. For older versions of pdflatex and for dvips the complete document is
inserted and a warning is printed.
• interpolate=htrue or falsei selects whether the image should be “smoothed” when zoomed. False
by default.
• mask=hmask namei selects a transparency mask. The mask must previously be declared using
\pgfdeclaremask (see below). This option only has an effect for pdf. Not all viewers support
masking.
1062
\pgfdeclareimage[interpolate=true,height=1cm]{image1}{brave-gnu-world-logo}
\pgfdeclareimage[interpolate=true,width=1cm,height=1cm]{image2}{brave-gnu-world-logo}
\pgfdeclareimage[interpolate=true,height=1cm]{image3}{brave-gnu-world-logo}
\pgfaliasimage{hnew image namei}{hexisting image namei}
The {hexisting image namei} is “cloned” and the {hnew image namei} can now be used whenever the
original image is used. This command is useful for creating aliases for alternate extensions and for
accessing the last image inserted using \pgfimage.
Example: \pgfaliasimage{image.!30!white}{image.!25!white}
105.3
Using an Image
\pgfuseimage{himage namei}
Inserts a previously declared image into the normal text. If you wish to use it in a {pgfpicture}
environment, you must put a \pgftext around it.
If the macro \pgfalternateextension expands to some nonempty halternate extensioni, pgf will first
try to use the image named himage namei.halternate extensioni. If this image is not defined, pgf will
next check whether halternate extensioni contains a ! character. If so, everything up to this exclamation
mark and including it is deleted from halternate extensioni and the pgf again tries to use the image
himage namei.halternate extensioni. This is repeated until halternate extensioni no longer contains a !.
Then the original image is used.
The xxcolor package sets the alternate extension to the current color mixin.
\pgfdeclareimage[interpolate=true,width=1cm,height=1cm]
{image1}{brave-gnu-world-logo}
\pgfdeclareimage[interpolate=true,width=1cm]{image2}{brave-gnu-world-logo}
\pgfdeclareimage[interpolate=true,height=1cm]{image3}{brave-gnu-world-logo}
\begin{pgfpicture}
\pgftext[at=\pgfpoint{1cm}{5cm},left,base]{\pgfuseimage{image1}}
\pgftext[at=\pgfpoint{1cm}{3cm},left,base]{\pgfuseimage{image2}}
\pgftext[at=\pgfpoint{1cm}{1cm},left,base]{\pgfuseimage{image3}}
\pgfpathrectangle{\pgfpoint{1cm}{5cm}}{\pgfpoint{1cm}{1cm}}
\pgfpathrectangle{\pgfpoint{1cm}{3cm}}{\pgfpoint{1cm}{1cm}}
\pgfpathrectangle{\pgfpoint{1cm}{1cm}}{\pgfpoint{1cm}{1cm}}
\pgfusepath{stroke}
\end{pgfpicture}
The following example demonstrates the effect of using \pgfuseimage inside a colormixin environment.
\pgfdeclareimage[interpolate=true,width=1cm,height=1cm]
{image1.!25!white}{brave-gnu-world-logo.25}
\pgfdeclareimage[interpolate=true,width=1cm]
{image2.25!white}{brave-gnu-world-logo.25}
\pgfdeclareimage[interpolate=true,height=1cm]
{image3.white}{brave-gnu-world-logo.25}
\begin{colormixin}{25!white}
\begin{pgfpicture}
\pgftext[at=\pgfpoint{1cm}{5cm},left,base]{\pgfuseimage{image1}}
\pgftext[at=\pgfpoint{1cm}{3cm},left,base]{\pgfuseimage{image2}}
\pgftext[at=\pgfpoint{1cm}{1cm},left,base]{\pgfuseimage{image3}}
\pgfpathrectangle{\pgfpoint{1cm}{5cm}}{\pgfpoint{1cm}{1cm}}
\pgfpathrectangle{\pgfpoint{1cm}{3cm}}{\pgfpoint{1cm}{1cm}}
\pgfpathrectangle{\pgfpoint{1cm}{1cm}}{\pgfpoint{1cm}{1cm}}
\pgfusepath{stroke}
\end{pgfpicture}
\end{colormixin}
\pgfalternateextension
You should redefine this command to install a different alternate extension.
Example: \def\pgfalternateextension{!25!white}
1063
\pgfimage[hoptionsi]{hfilenamei}
Declares the image under the name pgflastimage and immediately uses it. You can “save” the image
for later usage by invoking \pgfaliasimage on pgflastimage.
\begin{colormixin}{25!white}
\begin{pgfpicture}
\pgftext[at=\pgfpoint{1cm}{5cm},left,base]
{\pgfimage[interpolate=true,width=1cm,height=1cm]{brave-gnu-world-logo}}
\pgftext[at=\pgfpoint{1cm}{3cm},left,base]
{\pgfimage[interpolate=true,width=1cm]{brave-gnu-world-logo}}
\pgftext[at=\pgfpoint{1cm}{1cm},left,base]
{\pgfimage[interpolate=true,height=1cm]{brave-gnu-world-logo}}
\pgfpathrectangle{\pgfpoint{1cm}{5cm}}{\pgfpoint{1cm}{1cm}}
\pgfpathrectangle{\pgfpoint{1cm}{3cm}}{\pgfpoint{1cm}{1cm}}
\pgfpathrectangle{\pgfpoint{1cm}{1cm}}{\pgfpoint{1cm}{1cm}}
\pgfusepath{stroke}
\end{pgfpicture}
\end{colormixin}
105.4
Masking an Image
\pgfdeclaremask[hoptionsi]{hmask namei}{hfilenamei}
Declares a transparency mask named hmask namei (called a soft mask in the pdf specification). This
mask is read from the file hfilenamei. This file should contain a grayscale image that is as large as the
actual image. A white pixel in the mask will correspond to “transparent,” a black pixel to “solid,” and
gray values correspond to intermediate values. The mask must have a single “color channel.” This means
that the mask must be a “real” grayscale image, not an rgb-image in which all rgb-triples happen to
have the same components.
You can only mask images the are in a “pixel format.” These are .jpg and .png. You cannot mask
.pdf images in this way. Also, again, the mask file and the image file must have the same size.
The following options may be given:
• matte={hcolor componentsi} sets the so-called matte of the actual image (strangely, this has to be
specified together with the mask, not with the image itself). The matte is the color that has been
used to preblend the image. For example, if the image has been preblended with a red background,
then hcolor componentsi should be set to {1 0 0}. The default is {1 1 1}, which is white in the
rgb model.
The matte is specified in terms of the parent’s image color space. Thus, if the parent is a grayscale
image, the matte has to be set to {1}.
Example:
1064
%% Draw a large colorful background
\pgfdeclarehorizontalshading{colorful}{5cm}{color(0cm)=(red);
color(2cm)=(green); color(4cm)=(blue); color(6cm)=(red);
color(8cm)=(green); color(10cm)=(blue); color(12cm)=(red);
color(14cm)=(green)}
\hbox{\pgfuseshading{colorful}\hskip-14cm\hskip1cm
\pgfimage[height=4cm]{brave-gnu-world-logo}\hskip1cm
\pgfimage[height=4cm]{brave-gnu-world-logo-mask}\hskip1cm
\pgfdeclaremask{mymask}{brave-gnu-world-logo-mask}
\pgfimage[mask=mymask,height=4cm,interpolate=true]{brave-gnu-world-logo}}
1065
106
106.1
Externalizing Graphics
Overview
There are two fundamentally different ways of inserting graphics into a TEX-document. First, you can create
a graphic using some external program like xfig or InDesign and then include this graphic in your text.
This is done using commands like \includegraphics or \pgfimage. In this case, the graphic file contains
all the low-level graphic commands that describe the picture. When such a file is included, all TEX has to
worry about is the size of the picture; the internals of the picture are unknown to TEX and it does not care
about them.
The second method of creating graphics is to use a special package that transforms TEX-commands like
\draw or \psline into appropriate low-level graphic commands. In this case, TEX has to do all the hard
work of “typesetting” the picture and if a picture has a complicated internal structure this may take a lot of
time.
While pgf was created to facilitate the second method of creating pictures, there are two main reasons
why you may need to employ the first method of image-inclusion, nevertheless:
1. Typesetting a picture using TEX can be a very time-consuming process. If TEX needs a minute to
typeset a picture, you do not want to wait this minute when you reTEX your document after having
changed a single comma.
2. Some users, especially journal editors, may not be able to process files that contain pgf commands –
for the simple reason that the systems of many publishing houses do not have pgf installed.
In both cases, the solution is to “extract” or “externalize” pictures that would normally be typeset every
time a document is TEXed. Once the pictures have been extracted into separate graphics files, these graphic
files can be reinserted into the text using the first method.
Extracting a graphic from a file is not as easy as it may sound at first since TEX cannot write parts of
its output into different files and a bit of trickery is needed. The following macros simplify the workflow:
1. You have to tell pgf which files will be used for which pictures. To do so, you enclose each picture
that you wish to be “externalized” in a pair of \beginpgfgraphicnamed and \endpgfgraphicnamed
macros.
2. The next step is to generate the extracted graphics. For this you run TEX with the \jobname set to the
graphic file’s name. This will cause \pgfname to behave in a very special way: All of your document
will simply be thrown away, except for the single graphic having the same name as the current jobname.
3. After you have run TEX once for each graphic that your wish to externalize, you can rerun TEX on
your document normally. This will have the following effect: Each time a \beginpgfgraphicnamed is
encountered, pgf checks whether a graphic file of the given name exists (if you did step 2, it will). If
this graphic file exists, it will be input and the text till the corresponding \endpgfgraphicnamed will
be ignored.
In the rest of this section, the above workflow is explained in more detail.
106.2
Workflow Step 1: Naming Graphics
In order to put each graphic in an external file, you first need to tell pgf the names of these files.
\beginpgfgraphicnamed{hfile name prefix i}
This command indicates that everything up to the next call of \endpgfgraphicnamed is part of a
graphic that should be placed in a file named hfile name prefix i.hsuffix i, where the hsuffix i depends on
your backend driver. Typically, hsuffix i will be dvi or pdf.
Here is a typical example of how this command is used:
1066
% In file main.tex:
...
As we see in Figure~\ref{fig1}, the world is flat.
\begin{figure}
\beginpgfgraphicnamed{graphic-of-flat-world}
\begin{tikzpicture}
\fill (0,0) circle (1cm);
\end{tikzpicture}
\endpgfgraphicnamed
\caption{The flat world.}
\label{fig1}
\end{figure}
Each graphic to be externalized should have a unique name. Note that this name will be used as the
name of a file in the file system, so it should not contain any funny characters.
This command can have three different effects:
1. The easiest situation arises if there does not yet exist a graphic file called hfile name prefix i.hsuffix i,
where the hsuffix i is one of the suffixes understood by your current backend driver (so pdf or jpg
if you use pdftex, eps if you use dvips, and so on). In this case, both this command and the
\endpgfgraphicnamed command simply have no effect.
2. A more complex situation arises when a graphic file named hfile name prefix i.hsuffix i does exist.
In this case, this graphic file is included using the \includegraphics command13 . Furthermore,
the text between \beginpgfgraphicnamed and \endpgfgraphicnamed is ignored.
When the text is “ignored,” what actually happens is that all text up to the next occurrence of
\endpgfgraphicnamed is thrown away without any macro expansion. This means, in particular,
that (a) you cannot put \endpgfgraphicnamed inside a macro and (b) the macros used in the
graphics need not be defined at all when the graphic file is included.
3. The most complex behaviour arises when current the \jobname equals the hfile name prefix i and,
furthermore, the real job name has been declared. The behaviour for this case is explained later.
Note that the \beginpgfgraphicnamed does not really have any effect until you have generated the
graphic files named. Till then, this command is simply ignored. Also, if you delete the graphics file
later on, the graphics are typeset normally once more.
\endpgfgraphicnamed
This command just marks the end of the graphic that should be externalized.
106.3
Workflow Step 2: Generating the External Graphics
We have now indicated all the graphics for which we would like graphic files to be generated. In order to
generate the files, you now need to modify the \jobname appropriately. This is done in two steps:
1. You use the following command to tell pgf the real name of your .tex file:
\pgfrealjobname{hnamei}
Tells pgf the real name of your job. For instance, if you have a file called survey.tex that
contains two graphics that you wish to be called survey-graphic1 and survey-graphic2, then
you should write the following.
% This is file survey.tex
\documentclass{article}
...
\usepackage{tikz}
\pgfrealjobname{survey}
2. You run TEX with the \jobname set to the name of the graphic for which you need an external graphic
to be generated. To set the \jobname, you use the --jobname= option of TEX:
bash> latex --jobname=survey-graphic1 survey.tex
13 Actually, the command key /pgf/images/include external is invoked which calls an appropriate \includegraphics command.
1067
The following things will now happen:
1. \pgfrealjobname notices that the \jobname is not the “real” jobname and, thus, must be the name of
a graphic that is to be put in an external file.
2. At the beginning of the document, pgf changes the definition of TEX’s internal \shipout macro. The
new shipout macro simply throws away the output. This means that the document is typeset normally,
but no output is produced.
3. When the \beginpgfgraphicnamed{hnamei} command is encountered where the hnamei is the
same as the current \jobname, then a TEX-box is started and heverythingi up to the following
\endpgfgraphicnamed command is stored inside this box.
Note that, typically, heverythingi will contain just a single {tikzpicture} or {pgfpicture} environment. However, this need not be the case, you can use, say, a {pspicture} environment as heverythingi
or even just some normal TEX-text.
4. At the \endpgfgraphicnamed, the box is shipped out using the original \shipout command. Thus,
unlike everything else, the contents of the graphic is made part of the output.
5. When the box containing the graphic is shipped out, the paper size is modified such that it is exactly
equal to the height and width of the box.
The net effect of everything described above is that the two commands
bash> latex --jobname=survey-graphic1 survey.tex
bash> dvips survey-graphic1
produce a file called survey-graphic1.ps that consists of a single page that contains exactly the graphic
produced by the code between \beginpgfgraphicnamed{survey-graphic1} and \endpgfgraphicnamed.
Furthermore, the size of this single page is exactly the size of the graphic.
If you use pdfTEX, producing the graphic is even simpler:
bash> pdflatex --jobname=survey-graphic1 survey.tex
produces the single-page pdf-file survey-graphic1.pdf.
106.4
Workflow Step 3: Including the External Graphics
Once you have produced all the pictures in the text, including them into the main document is easy: Simply
run TEX again without any modification of the \jobname. In this case the \pgfrealjobname command
will notice that the main file is, indeed, the main file. The main file will then be typeset normally and the
\beginpgfgraphicnamed commands also behave normally, which means that they will try to include the
generated graphic files – which is exactly what you want.
Suppose that you wish to send your survey to a journal that does not have pgf installed. In this case,
you now have all the necessary external graphics, but you still need pgf to automatically include them
instead of the executing the picture code! One way to solve this problem is to simply delete all of the pgf or
Tik Z code from your survey.tex and instead insert appropriate \includegraphics commands “by hand.”
However, there is a better way: You input the file pgfexternal.tex.
File pgfexternal.tex
This file defines the command \beginpgfgraphicnamed and causes it to have the following effect: It includes the graphic file given as a parameter to it and then gobbles everything up to
\endpgfgraphicnamed.
Since \beginpgfgraphicnamed does not do macro expansion as it searches for \endpgfgraphicnamed,
it is not necessary to actually include the packages necessary for creating the graphics. So the idea is
that you comment out things like \usepackage{tikz} and instead say \input pgfexternal.tex.
Indeed, the contents of this file is simply the following line:
\long\def\beginpgfgraphicnamed#1#2\endpgfgraphicnamed{\includegraphics{#1}}
Instead of \input pgfexternal.tex you could also include this line in your main file.
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As a final remark, note that the baseline option does not work directly with pictures written to an
external graphic file. The simple reason is that there is no way to store this baseline information in an
external graphic file. To allow the baseline option (or any TEX construction with non-zero depth), the
baseline information is stored into a separate file. This file is named {himage filei}.dpth and contains
something like 5pt.
So, if you need baseline information, you will have to keep the external graphic file together with its .dpth
file. Furthermore, the short command in \input pgfexternal.tex is no longer enough because it ignores
any baseline information. You will need to use \input pgfexternalwithdepth.tex instead (it is shown
below). It is slightly longer, but it can be used in the same way as pgfexternal.tex.
(initially \pgfimage{#1})
/pgf/images/include external
This key constitutes the public interface to exchange the \includegraphics command used for the
image inclusion.
Redefining this key allows to provide bounding box or viewport options:
\pgfkeys{/pgf/images/include external/.code={\includegraphics[viewport=0 0 211.28 175.686]{#1}}}
Do not forget the .code here which redefines the command.
One application could be image externalization and bounding box restrictions: As far as I know, a .pdf
graphics with restricted bounding box is always cropped (which is not always desired). One solution
could be to use latex and dvips which doesn’t have this restriction. Another is to manually provide
the viewport option as shown above.
A possible value for viewport can be found in the .pdf image, search for /MediaBox = [ ...
106.5
].
A Complete Example
Let us now have a look at a simple, but complete example. We start out with a normal file called survey.tex
that has the following contents:
% This is the file survey.tex
\documentclass{article}
\usepackage{graphics}
\usepackage{tikz}
\begin{document}
In the following figure, we see a circle:
\begin{tikzpicture}
\fill (0,0) circle (10pt);
\end{tikzpicture}
By comparison, in this figure we see a rectangle:
\begin{tikzpicture}
\fill (0,0) rectangle (10pt,10pt);
\end{tikzpicture}
\end{document}
Now our editor tells us that the publisher will need all figures to be provided in separate PostScript
or .pdf-files. For this, we enclose all figures in ...graphicnamed-pairs and we add a call to the
\pgfrealjobname macro:
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% This is the file survey.tex
\documentclass{article}
\usepackage{graphics}
\usepackage{tikz}
\pgfrealjobname{survey}
\begin{document}
In the following figure, we see a circle:
\beginpgfgraphicnamed{survey-f1}
\begin{tikzpicture}
\fill (0,0) circle (10pt);
\end{tikzpicture}
\endpgfgraphicnamed
By comparison, in this figure we see a rectangle:
\beginpgfgraphicnamed{survey-f2}
\begin{tikzpicture}
\fill (0,0) rectangle (10pt,10pt);
\end{tikzpicture}
\endpgfgraphicnamed
\end{document}
After these changes, typesetting the file will still yield the same output as it did before – after all, we
have not yet created any external graphics.
To create the external graphics, we run pdflatex twice, once for each graphic:
bash> pdflatex --jobname=survey-f1 survey.tex
This is pdfTeX, Version 3.141592-1.40.3 (Web2C 7.5.6)
entering extended mode
(./survey.tex
LaTeX2e <2005/12/01>
...
) [1] (./survey-f1.aux) )
Output written on survey-f1.pdf (1 page, 1016 bytes).
Transcript written on survey-f1.log.
bash> pdflatex --jobname=survey-f2 survey.tex
This is pdfTeX, Version 3.141592-1.40.3 (Web2C 7.5.6)
entering extended mode
(./survey.tex
LaTeX2e <2005/12/01>
...
(./survey-f2.aux) )
Output written on survey-f2.pdf (1 page, 1002 bytes).
Transcript written on survey-f2.log.
We can now send the two generated graphics (survey-f1.pdf and survey-f2.pdf) to the editor. However, the publisher cannot use our survey.tex file, yet. The reason is that it contains the command
\usepackage{tikz} and they do not have pgf installed.
Thus, we modify the main file survey.tex as follows:
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% This is the file survey.tex
\documentclass{article}
\usepackage{graphics}
\input pgfexternal.tex
% \usepackage{tikz}
% \pgfrealjobname{survey}
\begin{document}
In the following figure, we see a circle:
\beginpgfgraphicnamed{survey-f1}
\begin{tikzpicture}
\fill (0,0) circle (10pt);
\end{tikzpicture}
\endpgfgraphicnamed
By comparison, in this figure we see a rectangle:
\beginpgfgraphicnamed{survey-f2}
\begin{tikzpicture}
\fill (0,0) rectangle (10pt,10pt);
\end{tikzpicture}
\endpgfgraphicnamed
\end{document}
If we now run pdfLATEX, then, indeed, pgf is no longer needed:
bash> pdflatex survey.tex
This is pdfTeX, Version 3.141592-1.40.3 (Web2C 7.5.6)
entering extended mode
(./survey.tex
LaTeX2e <2005/12/01>
Babel and hyphenation patterns for english, ..., loaded.
(/usr/local/gwTeX/texmf.texlive/tex/latex/base/article.cls
Document Class: article 2005/09/16 v1.4f Standard LaTeX document class
(/usr/local/gwTeX/texmf.texlive/tex/latex/base/size10.clo))
(/usr/local/gwTeX/texmf.texlive/tex/latex/graphics/graphics.sty
(/usr/local/gwTeX/texmf.texlive/tex/latex/graphics/trig.sty)
(/usr/local/gwTeX/texmf.texlive/tex/latex/config/graphics.cfg)
(/usr/local/gwTeX/texmf.texlive/tex/latex/pdftex-def/pdftex.def))
(/Users/tantau/Library/texmf/tex/generic/pgf/generic/pgf/utilities/pgfexternal.
tex) (./survey.aux)
(/usr/local/gwTeX/texmf.texlive/tex/context/base/supp-pdf.tex
[Loading MPS to PDF converter (version 2006.09.02).]
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