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AC-DIAMOND is a DNA-protein alignment tool
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AC-DIAMOND attempts to speed up DIAMOND via better SIMD parallelization and compressed indexing. Experimental results show that AC-DIAMOND was about 6~7 times faster than DIAMOND on aligning DNA reads or contigs while retaining the essentially the similar sensitivity. AC-DIAMOND was developped based on DIAMOND v0.7.9.


  1. download the source code and get
  2. unzip the file: unzip
  3. cd AC-DIAMOND-master/src/
  4. install boost: ./install-boost
  5. compile the source code: make
  6. cd ../bin/, the binary code of AC-DIAMOND is found

Getting Started

  1. build index: ./ac-diamond makedb --in nr.fa -d nr
  2. align: ./ac-diamond align -d nr -q query.fa -a matches -t <temporary directory>
  3. view alignment results in blast format: ./ac-diamond view -a matches.daa -o matches.m8

Sensitivity Setting

AC-DIAMOND supports three different modes for searching alignments, i.e. the fast mode, sensitive-1 mode and sensitive-2 mode. Assume the query sequences are in the file "query.fa" and the reference sequences are in the file "ref.fa". They are all stored in FASTA format.

Fast mode:

  1. Build the index for the reference "ref.fa" and put the index in the file "" using the following command:

    ./ac-diamond makedb --in ref.fa -d -b 4

  2. Search for alignments and put those with e-value at most 0.001 in the file "acd.result.daa" using the following command:

    ./ac-diamond align -d -q query.fa -a acd.result -e 0.001 -z 6

  3. Note that the alignments in the file "acd.result.daa" are not in blast output format. We can change their format using the following command:

    ./ac-diamond view -a acd.result.daa -o acd.result.m8

Sensitive-2 mode:

  1. Create the index:

    ./ac-diamond makedb --in ref.fa -d acd.sensitive.index --sensitive -b 4

  2. Search for alignments:

    ./ac-diamond align -d acd.sensitive.index -q query.fa -a acd.result --sensitive -e 0.001 -z 6

  3. Convert the output format:

    ./ac-diamond view -a acd.result.daa -o acd.result.m8

Sensitive-1 mode:

The sensitive-1 mode is in fact a pipeline, which first uses the fast mode to find alignments for most queries, and then uses the sensitive-2 mode to find alignments for the remaining queries. To run AC-DIAMOND with sensitive-1 mode, we can use the script "", which is in the scripts/ folder:

./ > acd.result.m8

The alignment results, which are already in blast output format, will be put in the file "acd.result.m8". To run the script successfully, the following files should also be in the same directory as "":

  1. The index files "" and "acd.sensitive.index" for the fast mode and sensitive-2 mode, which are created as described above.
  2. The "query.fa" containing the query sequences in FASTA format.
  3. The python script "", which is in scripts/ folder.
  4. The binary code of AC-DIAMOND.


Commands are issued as the first parameter on the command line and set the task to be run by the program.

Command Description
makedb Create AC-DIAMOND formatted reference database from a FASTA input file.
align Align translated DNA query sequences against a protein reference database.
view Generate formatted output from DAA files.

Makedb options

Option Short Default Description
--threads -p max Number of CPU threads.
--in     Path to protein reference database file in FASTA format (may be gzip compressed).
--db -d   Path to AC-DIAMOND database file.
--block-size -b 4 Block size in billions of sequence letters to be processed at a time.
--sensitive     Build the index, which will be used in the sensitive-1 or sensitive-2 modes.

General options

Option Short Default Description
--threads -p max Number of CPU threads.
--db -d   Path to AC-DIAMOND database file (not including the file extension).
--query -q   Path to query input file in FASTA or FASTQ format (may be gzip compressed).
--query-block-size -z 6 query sequence block size in billions of letters
--daa -a   Path to output file in DAA format (extension .daa will be appended).

Scoring & Reporting Options

Option Short Default Description
--gapopen   11 Gap open penalty.
--gapextend   1 Gap extension penalty.
--matrix   BLOSUM62 Scoring matrix.
--max-target-seqs -k 25 The maximum number of target sequences per query to keep alignments for.
--top     Keep alignments within the given percentage range of the top alignment score for a query (overrides –max-target-seqs option).
--evalue -e 0.001 Maximum expected value to keep an alignment.
--min-score     Minimum bit score to keep an alignment. Setting this option will override the --evalue parameter.

Memory & performance options

Option Short Default Description
--tmpdir -t /dev/shm Directory to be used for temporary storage.

View options

Option Short Default Description
--daa -a   Path to input file in DAA format.
--out -o   Path to output file.
--outfmt -f   Format of output file. (tab = BLAST tabular format; sam = SAM format)
--compress   0 Compression for output file (0=none, 1=gzip).
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