Google's R Style Guide

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Google's R Style Guide

http://google-styleguide.googlecode.com/svn/trunk...

Google's R Style Guide
R is a high-level programming language used primarily for statistical
computing and graphics. The goal of the R Programming Style Guide is to
make our R code easier to read, share, and verify. The rules below were
designed in collaboration with the entire R user community at Google.

Summary: R Style Rules
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File Names: end in .R
Identifiers: variable.name, FunctionName, kConstantName
Line Length: maximum 80 characters
Indentation: two spaces, no tabs
Spacing
Curly Braces: first on same line, last on own line
Assignment: use <-, not =
Semicolons: don't use them
General Layout and Ordering
Commenting Guidelines: all comments begin with # followed by a
space; inline comments need two spaces before the #
Function Definitions and Calls
Function Documentation
Example Function
TODO Style: TODO(username)

Summary: R Language Rules
1. attach: avoid using it
2. Functions: errors should be raised using stop()
3. Objects and Methods: avoid S4 objects and methods when possible;
never mix S3 and S4

1. Notation and Naming
File Names
File names should end in
GOOD: predict_ad_revenue.R
BAD: foo.R
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.R

and, of course, be meaningful.

08/29/2011 07:54 PM

Google's R Style Guide

http://google-styleguide.googlecode.com/svn/trunk...

Identifiers
Don't use underscores ( _ ) or hyphens ( - ) in identifiers. Identifiers
should be named according to the following conventions. Variable
names should have all lower case letters and words separated with
dots (.); function names have initial capital letters and no dots
(CapWords); constants are named like functions but with an initial k.
variable.name

GOOD: avg.clicks
BAD: avg_Clicks , avgClicks
FunctionName

GOOD: CalculateAvgClicks
BAD: calculate_avg_clicks , calculateAvgClicks
Make function names verbs.
Exception: When creating a classed object, the function name
(constructor) and class should match (e.g., lm).
kConstantName

2. Syntax
Line Length
The maximum line length is 80 characters.
Indentation
When indenting your code, use two spaces. Never use tabs or mix
tabs and spaces.
Exception: When a line break occurs inside parentheses, align the
wrapped line with the first character inside the parenthesis.
Spacing
Place spaces around all binary operators (=, +, -, <-, etc.).
Exception: Spaces around ='s are optional when passing parameters
in a function call.
Do not place a space before a comma, but always place one after a
comma.
GOOD:
tabPrior <- table(df[df$daysFromOpt < 0, "campaignid"])

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08/29/2011 07:54 PM

Google's R Style Guide

http://google-styleguide.googlecode.com/svn/trunk...

total <- sum(x[, 1])
total <- sum(x[1, ])

BAD:
tabPrior <- table(df[df$daysFromOpt<0, "campaignid"]) # Needs spaces around '<'
tabPrior <- table(df[df$daysFromOpt < 0,"campaignid"]) # Needs a space after the comma
tabPrior<- table(df[df$daysFromOpt < 0, "campaignid"]) # Needs a space before 
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