This program reads one or more input FASTA files. For each file it computes a variety of statistics, and then prints a summary of the statistics as output.
In the examples below, $ indicates the command line prompt.
This program is released as open source software under the terms of MIT License.
Clone this repository:
$ git clone https://github.com/USERNAME/biodemopython
Move into the repository directory:
$ cd biodemopython
Biodemopython can be installed using pip in a variety of ways ($ indicates the command line prompt):
- Inside a virtual environment:
$ python3 -m venv biodemopython_dev
$ source biodemopython_dev/bin/activate
$ pip install -U /path/to/biodemopython
- Into the global package database for all users:
$ pip install -U /path/to/biodemopython
- Into the user package database (for the current user only):
$ pip install -U --user /path/to/biodemopython
Biodemopython accepts zero or more FASTA filenames on the command line. If zero filenames are specified it reads a single FASTA file from the standard input device (stdin). Otherwise it reads each named FASTA file in the order specified on the command line. Biodemopython reads each input FASTA file, computes various statistics about the contents of the file, and then displays a tab-delimited summary of the statistics as output. Each input file produces at most one output line of statistics. Each line of output is prefixed by the input filename or by the text "stdin" if the standard input device was used.
Biodemopython processes each FASTA file one sequence at a time. Therefore the memory usage is proportional to the longest sequence in the file.
An optional command line argument --minlen can be supplied. Sequences with length strictly less than the given value will be ignored by biodemopython and do not contribute to the computed statistics. By default --minlen is set to zero.
These are the statistics computed by biodemopython, for all sequences with length greater-than-or-equal-to --minlen:
- NUMSEQ: the number of sequences in the file satisfying the minimum length requirement.
- TOTAL: the total length of all the counted sequences.
- MIN: the minimum length of the counted sequences.
- AVERAGE: the average length of the counted sequences rounded down to an integer.
- MAX: the maximum length of the counted sequences.
If there are zero sequences counted in a file, the values of MIN, AVERAGE and MAX cannot be computed. In that case biodemopython will print a dash (-) in the place of the numerical value. Note that when --minlen is set to a value greater than zero it is possible that an input FASTA file does not contain any sequences with length greater-than-or-equal-to the specified value. If this situation arises biodemopython acts in the same way as if there are no sequences in the file.
Biodemopython can display usage information on the command line via the -h or --help argument:
$ biodemopython -h
usage: biodemopython [-h] [--minlen N] [--version] [--log LOG_FILE]
[FASTA_FILE [FASTA_FILE ...]]
Print fasta stats
positional arguments:
FASTA_FILE Input FASTA files
optional arguments:
-h, --help show this help message and exit
--minlen N Minimum length sequence to include in stats (default 0)
--version show program's version number and exit
--log LOG_FILE record program progress in LOG_FILE
Biodemopython accepts zero or more named FASTA files on the command line. These must be specified following all other command line arguments. If zero files are named, biodemopython will read a single FASTA file from the standard input device (stdin).
There are no restrictions on the name of the FASTA files. Often FASTA filenames end in .fa or .fasta, but that is merely a convention, which is not enforced by biodemopython.
The example below illustrates biodemopython applied to a single named FASTA file called file1.fa:
$ biodemopython file1.fa
FILENAME NUMSEQ TOTAL MIN AVG MAX
file1.fa 5264 3801855 31 722 53540
The example below illustrates biodemopython applied to three named FASTA files called file1.fa, file2.fa and file3.fa:
$ biodemopython file1.fa file2.fa file3.fa
FILENAME NUMSEQ TOTAL MIN AVG MAX
file1.fa 5264 3801855 31 722 53540
file2.fa 5264 3801855 31 722 53540
file3.fa 5264 3801855 31 722 53540
The example below illustrates biodemopython reading a FASTA file from standard input. In this example we have redirected the contents of a file called file1.fa into the standard input using the shell redirection operator <:
$ biodemopython < file1.fa
FILENAME NUMSEQ TOTAL MIN AVG MAX
stdin 5264 3801855 31 722 53540
Equivalently, you could achieve the same result by piping a FASTA file into biodemopython:
$ cat file1.fa | biodemopython
FILENAME NUMSEQ TOTAL MIN AVG MAX
stdin 5264 3801855 31 722 53540
Biodemopython provides an optional command line argument --minlen which causes it to ignore (not count) any sequences in the input FASTA files with length strictly less than the supplied value.
The example below illustrates biodemopython applied to a single FASTA file called file.fawith a--minlenfilter of1000`.
$ biodemopython --minlen 1000 file.fa
FILENAME NUMSEQ TOTAL MIN AVG MAX
file1.fa 4711 2801855 1021 929 53540
If the --log FILE command line argument is specified, biodemopython will output a log file containing information about program progress. The log file includes the command line used to execute the program, and a note indicating which files have been processes so far. Events in the log file are annotated with their date and time of occurrence.
$ biodemopython --log bt.log file1.fasta file2.fasta
# normal biodemopython output appears here
# contents of log file displayed below
$ cat bt.log
12/04/2016 19:14:47 program started
12/04/2016 19:14:47 command line: /usr/local/bin/biodemopython --log bt.log file1.fasta file2.fasta
12/04/2016 19:14:47 Processing FASTA file from file1.fasta
12/04/2016 19:14:47 Processing FASTA file from file2.fasta
It is possible that the input FASTA file contains zero sequences, or, when the --minlen command line argument is used, it is possible that the file contains no sequences of length greater-than-or-equal-to the supplied value. In both of those cases biodemopython will not be able to compute minimum, maximum or average sequence lengths, and instead it shows output in the following way:
The example below illustrates biodemopython applied to a single FASTA file called empty.fa which contains zero sequences:
$ biodemopython empty.fa
FILENAME NUMSEQ TOTAL MIN AVG MAX
empty.fa 0 0 - - -
Biodemopython returns the following exit status values:
- 0: The program completed successfully.
- 1: File I/O error. This can occur if at least one of the input FASTA files cannot be opened for reading. This can occur because the file does not exist at the specified path, or biodemopython does not have permission to read from the file.
- 2: A command line error occurred. This can happen if the user specifies an incorrect command line argument. In this circumstance biodemopython will also print a usage message to the standard error device (stderr).
- 3: Input FASTA file is invalid. This can occur if biodemopython can read an input file but the file format is invalid.
XXX FIXME
$ cd biodemopython/python/biodemopython
$ python -m unittest -v biodemopython_test
A set of sample test input files is provided in the test_data folder.
$ biodemopython two_sequence.fasta
FILENAME TOTAL NUMSEQ MIN AVG MAX
two_sequence.fasta 2 357 120 178 237
Please submit bug reports and feature requests to the issue tracker on GitHub: