Diamond Manual
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diamond v0.9.6 June 7, 2017
The DIAMOND sequence aligner
Introduction
DIAMOND is a sequence aligner for protein and translated DNA searches and functions as a drop-
in replacement for the NCBI BLAST software tools. It is suitable for protein-protein search as well
as DNA-protein search on short reads and longer sequences including contigs and assemblies,
providing a speedup of BLAST ranging up to x20,000.
DIAMOND was published in Nature Methods in 2015 [1]. Please cite this paper when using
the program in published research.
Support & updates are available at http://github.com/bbuchfink/diamond/.
1 Quick start guide
We assume to have a protein database file in FASTA format named nr.faa and a file of DNA reads
that we want to align named reads.fna. In order to set up a reference database for DIAMOND,
the makedb command needs to be executed with the following command line:
diamond makedb --in nr.faa -d nr
This will create a binary DIAMOND database file with the specified name (nr.dmnd). The align-
ment task may then be initiated using the blastx command like this:
diamond blastx -d nr -q reads.fna -o matches.m8
The output file here is specified with the -o option and named matches.m8. By default, it is
generated in BLAST tabular format.
Note:
•The program may use quite a lot of memory and also temporary disk space. Should the
program fail due to running out of either one, you need to set a lower value for the block size
parameter -b (see 3.7).
•The default (fast) mode was mainly designed for short reads. For longer sequences, the
sensitive modes (options --sensitive or --more-sensitive) are recommended.
•The runtime of the program is not linear in the size of the query file and it is more efficient
for large query files (>1million sequences) than for smaller ones.
•Low complexity masking is applied to the query and reference sequences by default. Masked
residues appear in the output as X.
•The default e-value cutoff of DIAMOND is 0.001 while that of BLAST is 10, so by default the
program will search a lot more stringently than BLAST and not report weak hits.
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2 Installation & requirements
DIAMOND compiles as generic C++ code and has no particular requirements on the hardware
architecture, but it makes use of the SSE instruction set of the Intel/AMD x86-64 platform when
available and will run considerably faster on that platform. It runs on POSIX-compatible operating
systems (Linux, FreeBSD, OS X) as well as on Microsoft Windows.
A high-memory server is recommended for better performance, but the program can be run
on standard desktop computers or laptops.
Compiled binaries are available for download for Linux and Windows. Users of Max OS X need
to compile the software from source.
2.1 Binary download
2.1.1 Linux
A precompiled binary is available for recent Linux systems and may be downloaded for immediate
use:
wget http://github.com/bbuchfink/diamond/releases/download/v0.9.6/diamond-linux64.tar.gz
tar xzf diamond-linux64.tar.gz
The package contains a diamond binary for CPUs that support SSSE3 and a diamond-sse2 binary
for older CPUs. If both binaries do not work on your system, you need to compile the software
from source.
2.1.2 FreeBSD
On FreeBSD, you can use pkg install diamond to install the software.
2.1.3 Windows
A binary executable for Windows can be downloaded at the DIAMOND github page. You also
need to install the Visual C++ Redistributable.
2.2 Compiling from source
Compilation requires GCC 4.1 or later, CMake 2.6 or later as well as libpthread and zlib including
development headers. To compile DIAMOND from source, invoke the following commands on the
shell:
wget http://github.com/bbuchfink/diamond/archive/v0.9.6.tar.gz
tar xzf v0.9.6.tar.gz
cd diamond-0.9.6
mkdir bin
cd bin
cmake ..
make install
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Note:
•Use cmake -DCMAKE INSTALL PREFIX=... to install to a different prefix.
•Use cmake -DBUILD STATIC=ON to create a statically linked executable.
3 Command line options
3.1 Commands
Commands are issued as the first parameter on the command line and set the task to be run by
the program.
makedb
Create a DIAMOND formatted reference database from a FASTA input file.
blastp
Align protein query sequences against a protein reference database.
blastx
Align translated DNA query sequences against a protein reference database.
view
Generate formatted output from DAA files.
version
Print version information.
help
Print help message.
3.2 Makedb options
--in <file>
Path to the input protein reference database file in FASTA format (may be gzip compressed).
If this parameter is omitted, the input will be read from stdin.
--db/-d <file>
Path to the output DIAMOND database file.
3.3 General options
--threads/-p #
Number of CPU threads. By default, the program will auto-detect and use all available virtual
cores on the machine.
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3.4 Input options
--db/-d <file>
Path to the DIAMOND database file.
--query/-q <file>
Path to the query input file in FASTA or FASTQ format (may be gzip compressed). If this
parameter is omitted, the input will be read from stdin.
--query-gencode #
Genetic code used for translation of query in BLASTX mode. A list of possible values can
be found at the NCBI website. By default, the Standard Code is used. Note: changing the
genetic code is currently not fully supported for the DAA format.
--taxonmap <file>
Path to mapping file that maps NCBI protein accession numbers to taxon ids (gzip com-
pressed). This parameter is required when using the staxids field of the BLAST tabu-
lar format. The file can be downloaded from NCBI: ftp://ftp.ncbi.nlm.nih.gov/pub/
taxonomy/accession2taxid/prot.accession2taxid.gz. Note: this feature is currently not
supported when using the DAA format.
--min-orf/-l #
Ignore translated sequences that do not contain an open reading frame of at least this length.
By default this feature is disabled for sequences of length below 30, set to 20 for sequences
of length below 100, and set to 40 otherwise. Setting this option to 1will disable this feature.
3.5 Alignment options
--sensitive
This mode is a lot more sensitive that the default and generally recommended for aligning
longer sequences. The default mode is mainly designed for short read alignment, i.e. finding
significant matches of >50 bits on 30-40aa fragments.
--more-sensitive
This mode provides some additional sensitivity compared to the sensitive mode.
--gapopen #
Gap open penalty.
--gapextend #
Gap extension penalty.
--matrix <matrix name>
Scoring matrix. The following matrices are supported, with the default being BLOSUM62.
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Matrix Supported values for (gap open)/(gap extend) Default gap penalties
BLOSUM45 (10-13)/3; (12-16)/2; (16-19)/1 14/2
BLOSUM50 (9-13)/3; (12-16)/2; (15-19)/1 13/2
BLOSUM62 (6-11)/2; (9-13)/1 11/1
BLOSUM80 (6-9)/2; 13/2; 25/2; (9-11)/1 10/1
BLOSUM90 (6-9)/2; (9-11)/1 10/1
PAM250 (11-15)/3; (13-17)/2; (17-21)/1 14/2
PAM70 (6-8)/2; (9-11)/1 10/1
PAM30 (5-7)/2; (8-10)/1 9/1
--comp-based-stats (0,1)
Compositional bias correction of alignment scores. 0 means no score correction, 1 means
compositional bias correction as described in [2] (default). Compositionally biased se-
quences often cause false positive matches, which are effectively filtered by this algorithm
in a way similar to the composition based statistics used by BLAST [3].
--algo (0,1)
Algorithm for seed search. 0 means double-indexed and 1 means query-indexed. The
double-indexed algorithm is the program’s main algorithm, but it is inefficient for very small
query files, where the query-indexed algorithm should be used instead.
By default, the program will automatically choose one of the algorithms based on the size of
the query and database files. The algorithm used will be displayed at program startup.
Note that while the two algorithms are configured to provide roughly the same sensitivity for
the respective modes, results will not be exactly identical to each other.
3.6 Output options
--out/-o <file>
Path to the output file. If this parameter is omitted, the results will be written to the standard
output and all other program output will be suppressed.
--outfmt/-f #
Format of the output file. The following values are accepted:
0BLAST pairwise format.
5BLAST XML format.
6BLAST tabular format (default). This format can be customized, the 6may be followed by
a space-separated list of the following keywords, each specifying a field of the output.
qseqid Query Seq - id
qlen Query sequence length
sseqid Subject Seq - id
sallseqid All subject Seq - id(s), separated by a ’;’
slen Subject sequence length
qstart Start of alignment in query
qend End of alignment in query
sstart Start of alignment in subject
send End of alignment in subject
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qseq Aligned part of query sequence
sseq Aligned part of subject sequence
evalue Expect value
bitscore Bit score
score Raw score
length Alignment length
pident Percentage of identical matches
nident Number of identical matches
mismatch Number of mismatches
positive Number of positive - scoring matches
gapopen Number of gap openings
gaps Total number of gaps
ppos Percentage of positive - scoring matches
qframe Query frame
btop Blast traceback operations(BTOP)
staxids Unique Subject Taxonomy ID(s), separated by a ’;’ (in numerical order). This
field requires setting the --taxonmap parameter.
stitle Subject Title
salltitles All Subject Title(s), separated by a ’<>’
qcovhsp Query Coverage Per HSP
qtitle Query title
By default, there are 12 preconfigured fields: qseqid sseqid pident length mismatch
gapopen qstart qend sstart send evalue bitscore.
100 DIAMOND alignment archive (DAA). The DAA format is a proprietary binary format that
can subsequently be used to generate other output formats using the view command.
It is also supported by MEGAN and allows a quick import of results.
101 SAM format.
--salltitles
Include full length subject titles into the DAA format. By default, DAA files contain only the
shortened sequence id (up to the first blank character).
--compress (0,1)
Enable compression of the output file. 0 (default) means no compression, 1 means gzip
compression.
--max-target-seqs/-k #
The maximum number of target sequences per query to report alignments for (default=25).
Setting this to 0 will report all alignments that were found.
--top #
Report alignments within the given percentage range of the top alignment score for a query
(overrides --max-target-seqs option).
--evalue/-e #
Maximum expected value to report an alignment (default=0.001).
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--min-score #
Minimum bit score to report an alignment. Setting this option will override the --evalue
parameter.
--id #
Report only alignments above the given percentage of sequence identity.
--query-cover #
Report only alignments above the given percentage of query cover.
--subject-cover #
Report only alignments above the given percentage of subject cover.
--max-hsps #
The maximum number of HSPs per subject sequence to report for each query. By default,
this is set to 1, so only the single best HSP for each query/subject pair will be reported.
--unal (0,1)
Report unaligned queries (0=no, 1=yes). By default, unaligned queries are reported for the
BLAST pairwise, BLAST XML and SAM format.
--no-self-hits
Suppress reporting of identical self-hits between sequences.
3.7 Memory & performance options
--block-size/-b #
Block size in billions of sequence letters to be processed at a time. This is the main pa-
rameter for controlling the program’s memory usage. Bigger numbers will increase the use
of memory and temporary disk space, but also improve performance. The program can be
expected to use roughly six times this number of memory (in GB). So for the default value of
-b2.0, the memory usage will be about 12 GB.
--tmpdir/-t <directory>
Directory to be used for temporary storage. This is set to the output directory by default.
The amount of disk space that will be used depends on the program’s settings and your
data. As a general rule you should ensure that 100 GB of disk space are available here.
If you run the program in a cluster environment, and disk space is only available over a
slow network based file system, you may want to set the --tmpdir option to /dev/shm. This
will keep temporary information in memory and thus increase the program’s memory usage
substantially.
--index-chunks/-c #
The number of chunks for processing the seed index (default=4). This option can be addi-
tionally used to tune the performance. It is recommended to set this to 1 on a high memory
server, which will increase performance and memory usage, but not the usage of temporary
disk space.
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3.8 View options
--daa/-a <file>
Path to input file in DAA format.
--out/-o <file>
Path to output file. If this parameter is omitted, the results will be written to the standard
output and all other program output will be suppressed.
--outfmt/-f #
Format of the output file, see 3.6.
--compress (0,1)
Enable compression of the output file, see 3.6.
3.9 Advanced options
--freq-sd #
During the seed search, seeds with very high frequency in the queries or the database are
ignored. This option sets the number of standard deviations above the average frequency
for ignoring a seed. The default values are 50 in default mode, 10 in sensitive mode, and
200 in more-sensitive mode.
--band #
Dynamic programming band for seed extension. Initial seed hits are scanned across a band
of this length in both directions.
4 Support & FAQ
Support is provided by email or the GitHub issues page. For support requests it is usually helpful if
you provide details about your data (size and type of sequences) and your execution environment
(CPU cores, RAM, operating system).
Community feedback and feature requests are also appreciated.
1. The program runs for a very long time and the output file remains empty.
This is normal. Larger databases are split into chunks and the output is kept in temporary
files at first and only merged in the end.
2. There are no temporary files.
The temporary files are not visible using standard shell commands because unlink is in-
voked on them after creation, which ensures that the files will be removed in case of un-
graceful termination of the program.
3. Are results consistent for multiple calls of the program?
The program has a basic consistency guarantee that the same version run on the same
input with the same parameters will produce identical results, regardless of the hardware,
operating system, compiler, or number of CPU threads. If this was not the case, I would
consider it a bug.
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Beyond that, no guarantees of consistency can be made. DIAMOND like all fast align-
ers uses numerous heuristics that can alter results in unexpected ways. For example, it has
been noted that the top hit of a BLAST search can change depending on the -max target seqs
option. Because gapped extension is expensive, BLAST ranks all the subject sequences that
were hit for a query based on ungapped extensions at seed hits and considers only a subset
of the subjects for gapped extension. The pool of subjects considered is bigger for higher
values of -max target seqs, so in rare cases the true best hit may or may not make it to the
gapped extension stage depending on this parameter.
Effects like this seem counterintuitive to many users, but they are a natural byproduct of
heuristics used by all fast aligners. The only tools that can guarantee optimal results in any
sense of the word are rigorous search tools like SSEARCH.
5 Optimizing performance
You should take the time to configure the program to your needs instead of just running it with
default settings, as this will substantially optimize the use of system resources. Some points to
consider:
•Set the -e parameter (maximum expected value) as low as possible.
•Set the -k parameter (number of target sequences to report alignments for) as low as pos-
sible. This will improve performance and reduce the use of temporary disk space and the
size of the output files.
•Consider using the --top parameter instead of -k. For example, setting --top 5 will report
all alignments whose score is at most 5% lower than the top alignment score for a query.
•Configure the tabular output format to only report the output fields that are actually required
(see 3.6.).
•Use the BLAST tabular format for machine-based processing of the output. Use the XML
and SAM format only if required by your downstream tools or if you prefer it as a human-
readable format.
•Use the option --compress 1 to automatically generate gzip-compressed output files.
About
DIAMOND is developed by Benjamin Buchfink and distributed as Open Source under the GNU
Affero General Public License.
Bug reports, support and other inquiries may be sent to Benjamin Buchfink.
References
[1] Benjamin Buchfink, Chao Xie, and Daniel H. Huson. Fast and sensitive protein alignment
using diamond. Nature methods, 12(1):59–60, Jan 2015.
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diamond v0.9.6 June 7, 2017
[2] Maria Hauser, Martin Steinegger, and Johannes S ¨
oding. Mmseqs software suite for fast and
deep clustering and searching of large protein sequence sets. Bioinformatics (Oxford, Eng-
land), 32(9):1323–1330, May 2016.
[3] Yi-Kuo Yu and Stephen F. Altschul. The construction of amino acid substitution matrices for
the comparison of proteins with non-standard compositions. Bioinformatics (Oxford, England),
21(7):902–911, Apr 2005.
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