/tools/metag_tools/fastqsolexa_to_fasta_qual.py

  1#!/usr/bin/env python
  2
  3"""
  4convert fastqsolexa file to separated sequence and quality files.
  5
  6assume each sequence and quality score are contained in one line
  7the order should be:
  81st line: @title_of_seq
  92nd line: nucleotides
 103rd line: +title_of_qualityscore (might be skipped)
 114th line: quality scores 
 12(in three forms: a. digits, b. ASCII codes, the first char as the coding base, c. ASCII codes without the first char.)
 13
 14Usage:
 15%python fastqsolexa_to_fasta_qual.py <your_fastqsolexa_filename> <output_seq_filename> <output_score_filename>
 16"""
 17
 18import sys, os
 19from math import *
 20
 21assert sys.version_info[:2] >= ( 2, 4 )
 22
 23def stop_err( msg ):
 24    sys.stderr.write( "%s" % msg )
 25    sys.exit()
 26
 27def __main__():
 28    infile_name = sys.argv[1]
 29    outfile_seq = open( sys.argv[2], 'w' )
 30    outfile_score = open( sys.argv[3], 'w' )
 31    datatype = sys.argv[4]
 32    seq_title_startswith = ''
 33    qual_title_startswith = ''
 34    default_coding_value = 64
 35    fastq_block_lines = 0
 36    
 37    for i, line in enumerate( file( infile_name ) ):
 38        line = line.rstrip()
 39        if not line or line.startswith( '#' ):
 40            continue
 41        fastq_block_lines = ( fastq_block_lines + 1 ) % 4
 42        line_startswith = line[0:1]
 43        if fastq_block_lines == 1:
 44            # first line is @title_of_seq
 45            if not seq_title_startswith:
 46                seq_title_startswith = line_startswith
 47            if line_startswith != seq_title_startswith:
 48                outfile_seq.close()
 49                outfile_score.close()
 50                stop_err( 'Invalid fastqsolexa format at line %d: %s.' % ( i + 1, line ) )
 51            read_title = line[1:]
 52            outfile_seq.write( '>%s\n' % line[1:] )
 53        elif fastq_block_lines == 2:
 54            # second line is nucleotides
 55            read_length = len( line )
 56            outfile_seq.write( '%s\n' % line )
 57        elif fastq_block_lines == 3:
 58            # third line is +title_of_qualityscore ( might be skipped )
 59            if not qual_title_startswith:
 60                qual_title_startswith = line_startswith
 61            if line_startswith != qual_title_startswith:
 62                outfile_seq.close()
 63                outfile_score.close()
 64                stop_err( 'Invalid fastqsolexa format at line %d: %s.' % ( i + 1, line ) )    
 65            quality_title = line[1:]
 66            if quality_title and read_title != quality_title:
 67                outfile_seq.close()
 68                outfile_score.close()
 69                stop_err( 'Invalid fastqsolexa format at line %d: sequence title "%s" differes from score title "%s".' % ( i + 1, read_title, quality_title ) )
 70            if not quality_title:
 71                outfile_score.write( '>%s\n' % read_title )
 72            else:
 73                outfile_score.write( '>%s\n' % line[1:] )
 74        else:
 75            # fourth line is quality scores
 76            qual = ''
 77            fastq_integer = True
 78            # peek: ascii or digits?
 79            val = line.split()[0]
 80            try: 
 81                check = int( val )
 82                fastq_integer = True
 83            except:
 84                fastq_integer = False
 85                
 86            if fastq_integer:
 87                # digits
 88                qual = line
 89            else:
 90                # ascii
 91                quality_score_length = len( line )
 92                if quality_score_length == read_length + 1:
 93                    # first char is qual_score_startswith
 94                    qual_score_startswith = ord( line[0:1] )
 95                    line = line[1:]
 96                elif quality_score_length == read_length:
 97                    qual_score_startswith = default_coding_value
 98                else:
 99                    stop_err( 'Invalid fastqsolexa format at line %d: the number of quality scores ( %d ) is not the same as bases ( %d ).' % ( i + 1, quality_score_length, read_length ) )
100                for j, char in enumerate( line ):
101                    score = ord( char ) - qual_score_startswith    # 64
102                    qual = "%s%s " % ( qual, str( score ) )
103            outfile_score.write( '%s\n' % qual )
104              
105    outfile_seq.close()
106    outfile_score.close()
107
108if __name__ == "__main__": __main__() 
109