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  • Adamo
    Member
    • Jun 2010
    • 28

    #1

    Getting sequences into a bam file - psl2sam.pl

    Hello,

    I have a psl file, and convert it into sam format using psl2sam.pl (samtools).
    I'd like to know if there is a way of getting the target sequence in the sam file in place of the "*" placeholder?
    pslx format doesn't work either.

    I have found the code of some script that should do the job, but it doesn't work. Here is the script, if someone wants to see it:

    Code:
    #!/usr/bin/perl -w
    
    # Contact: nlw
    #this script combines a sam file with the sequences from a fasta file.  originally designed as a second step when converting blat (psl) to sam.
    
    
    $| = 1;
    
    ## SJC: Generic debug variable and print.
    my $DEBUG = 1;
    sub kvetch{
        my $foo = shift || '';
        print STDERR $foo . "\n" if $DEBUG;
    }
    
    
    use strict;
    use warnings;
    use Getopt::Std;
    use File::Copy;
    use Switch;
    
    my $lines_read = 0;
    my $lines_written = 0;
    my @filearray;
    my $lines_in_file = 0;
    my $start = time();
    my @buffer;
    
    ($lines_read, $lines_written, $lines_in_file) = &bowtie2sam;
    my $stop = time();
    my $time = $stop-$start;
    print STDERR "Done. Processed in " . $time . " sec \n";
    
    exit;
    
    sub bowtie2sam {
      my %opts = ();
      die("Usage: tab_merge_sam.pl <seq> <sam>\n") if (@ARGV == 0 && -t STDIN);
      my $seq_file = $ARGV[0];
      my $sam_file = $ARGV[1];
    
      my $tmp_seq = $seq_file . ".tmp";
      my $tmp_sam = $sam_file . ".tmp";
      my $merged_sam = $sam_file . ".seq_merged";
    
      print STDERR "Sorting sequence file \"$seq_file\"... ";
      `grep -v sequence $seq_file | sort > $tmp_seq`;
     
      print STDERR "Done.\n";
    
      print STDERR "Sorting sam file \"$sam_file\"... ";
      `sort $sam_file > $tmp_sam`;
    
      print STDERR "Done.\n";
    
      open(SAM, $tmp_sam);
      open(SEQ, $tmp_seq);
    
    
      my $wc_seq = `wc -l $tmp_seq`;
      my $lines_in_seq = (split(" ", $wc_seq))[0];
      my $lines_read_sam = 0;
      my $lines_written = 0;
      my $read_not_found = 0;
      my $reads_matched = 0;
      my $lines_read_seq = 0;
    
      print STDERR "there are " . $lines_in_seq . " lines in the file \"" . $seq_file . "\"\n";
      print STDERR "Merging...\n";
      my $sam_id = "";
    
      #there may be multiple alignments reported
      #for each of the reads in the tab file, find them in the sam file, add the hit counter
    
      while (<SEQ>) {
          $lines_read_seq++;
          my $seq_line = $_;
          chomp($seq_line);
          $seq_line =~ s/\s+/\t/g;
          my ($seq_id, $read_sequence) = split(/\t/,$seq_line);
    
          my $seq_found = 0;
          my $too_big = 0;
          my $seq_hits = 0; #counter for number of alignments for each sequence
          #print STDERR "line $lines_read_seq seq is $seq_id\n";
          my $flag = 0;
          while (!$flag) {
              last if eof(SAM);
              my $sam_line = <SAM>;  
              next if ($sam_line =~ /^\s*$/);
              my $line_length = length($sam_line);
              chomp($sam_line);
              $sam_line =~ s/\s+/\t/g;
              my @sam = split(/\t/, $sam_line);
              my $sam_id = $sam[0];
              my $strand = ($sam[1] == 0);
              #if ($sam_line =~ m/\Q$seq_id/) {  
              $lines_read_sam++;
              #print STDERR "line $lines_read_sam sam is $sam_id\n";
              if ($sam_id eq $seq_id) {
                  #add sequence to sam array
                  #$sam[9] = $strand ? $read_sequence : reverse_complement($read_sequence) ;
                  if ($strand) {
                      $sam[9] = $read_sequence;
                  } else {
                      #print STDERR "rc for read $sam_id at line $lines_read_sam\n";
                      $sam[9] = reverse_complement($read_sequence);
                  }
                  $seq_hits++;  
                  $sam[11] .= " HI:i:" . $seq_hits;
                  $reads_matched++;
                  #print STDERR "matched $seq_id at line $lines_read_sam of sam file\n";
                  print STDOUT join("\t", @sam) . "\n";      
              } elsif ($sam_id gt $seq_id) {
                  $lines_read_sam--;
                  #backup
                  seek(SAM,-$line_length,1);
                  #print STDERR "backing up to line $lines_read_sam of sam file\n";
                  $flag = 1;
              } else {
                  print STDOUT join("\t", @sam) . "\n";      
                  die;
              }  
          }
      }
      print STDERR "++++++++++++++++++++++++++++++++++\n";
      print STDERR "SAM read: $lines_read_sam\n";
      print STDERR "reads matched: $reads_matched\n";
      print STDERR "reads not found: $read_not_found\n";
      print STDERR "++++++++++++++++++++++++++++++++++\n";
      close(SAM);
      close(SEQ);
      unlink ($tmp_sam);
      unlink ($tmp_seq);
    }
    
    sub reverse_complement {
        my ($sequence) = @_;
        my $rc_sequence = "";
        my @array = split(//, $sequence);
        foreach my $c (@array) {
            switch ($c) {
                case "A" {$c = "T"}
                case "T" {$c = "A"}
                case "G" {$c = "C"}
                case "C" {$c = "G"}
            }
            $rc_sequence = $c . $rc_sequence
        }
        return $rc_sequence;
    }
    Thanks in advance!

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