Raw content of Bio::SeqIO::fastq
<![CDATA[# BioPerl module for Bio::SeqIO::fastq
#
# Cared for by Tony Cox <avc@sanger.ac.uk>
#
# Copyright Tony Cox
#
# You may distribute this module under the same terms as perl itself
# _history
# October 29, 2001 incept data
# POD documentation - main docs before the code
=head1 NAME
Bio::SeqIO::fastq - fastq sequence input/output stream
=head1 SYNOPSIS
Do not use this module directly. Use it via the Bio::SeqIO class.
=head1 DESCRIPTION
This object can transform Bio::Seq and Bio::Seq::SeqWithQuality
objects to and from fastq flat file databases.
Fastq is a file format used frequently at the Sanger Centre to bundle
a fasta sequence and its quality data. A typical fastaq entry takes
the from:
@HCDPQ1D0501
GATTTGGGGTTCAAAGCAGTATCGATCAAATAGTAAATCCATTTGTTCAACTCACAGTTT.....
+HCDPQ1D0501
!''*((((***+))%%%++)(%%%%).1***-+*''))**55CCF>>>>>>CCCCCCC65.....
Fastq files have sequence and quality data on a single line and the
quality values are single-byte encoded. To retrieve the decimal values
for qualities you need to subtract 33 (or Octal 41) from each byte and
then convert to a '2 digit + 1 space' integer. You can check if 33 is
the right number because the first byte which is always '!'
corresponds to a quality value of 0.
=head1 FEEDBACK
=head2 Mailing Lists
User feedback is an integral part of the evolution of this and other
Bioperl modules. Send your comments and suggestions preferably to one
of the Bioperl mailing lists. Your participation is much appreciated.
bioperl-l@bioperl.org - General discussion
http://bioperl.org/MailList.shtml - About the mailing lists
=head2 Reporting Bugs
Report bugs to the Bioperl bug tracking system to help us keep track
the bugs and their resolution.
Bug reports can be submitted via email or the web:
bioperl-bugs@bio.perl.org
http://bugzilla.bioperl.org/
=head1 AUTHORS - Tony Cox
Email: avc@sanger.ac.uk
=head1 APPENDIX
The rest of the documentation details each of the object
methods. Internal methods are usually preceded with a _
=cut
# Let the code begin...
package Bio::SeqIO::fastq;
use vars qw(@ISA);
use strict;
# Object preamble - inherits from Bio::Root::Object
use Bio::SeqIO;
use Bio::Seq::SeqFactory;
@ISA = qw(Bio::SeqIO);
sub _initialize {
my($self,@args) = @_;
$self->SUPER::_initialize(@args);
if( ! defined $self->sequence_factory ) {
$self->sequence_factory(new Bio::Seq::SeqFactory(-verbose => $self->verbose(), -type => 'Bio::Seq::SeqWithQuality'));
}
}
=head2 next_seq
Title : next_seq
Usage : $seq = $stream->next_seq()
Function: returns the next sequence in the stream
Returns : Bio::Seq::SeqWithQuality object
Args : NONE
=cut
sub next_seq {
my( $self ) = @_;
my $seq;
my $alphabet;
local $/ = "\n\@";
return unless my $entry = $self->_readline;
if ($entry eq '@') { # very first one
return unless $entry = $self->_readline;
}
my ($top,$sequence,$top2,$qualsequence) = $entry =~ /^
\@?(.+?)\n
([^\@]*?)\n
\+?(.+?)\n
(.*)\n
/xs
or $self->throw("Can't parse fastq entry");
my ($id,$fulldesc) = $top =~ /^\s*(\S+)\s*(.*)/
or $self->throw("Can't parse fastq header");
if ($id eq '') {$id=$fulldesc;} # FIX incase no space between \@ and name
$sequence =~ s/\s//g; # Remove whitespace
$qualsequence =~ s/\s//g;
if(length($sequence) != length($qualsequence)){
$self->warn("Fastq sequence/quality data length mismatch error\n");
$self->warn("Sequence: $top, seq length: ",length($sequence), " Qual length: ", length($qualsequence), " \n");
$self->warn("$sequence\n");
$self->warn("$qualsequence\n");
$self->warn("FROM ENTRY: \n\n$entry\n");
}
my @qual = split('', $qualsequence);
my $qual;
foreach (@qual) {$qual .= (unpack("C",$_) - 33) ." "};
# for empty sequences we need to know the mol.type
$alphabet = $self->alphabet();
if(length($sequence) == 0) {
if(! defined($alphabet)) {
# let's default to dna
$alphabet = "dna";
}
} else {
# we don't need it really, so disable
$alphabet = undef;
}
# create the SeqWithQuality object
$seq = $self->sequence_factory->create(
-qual => $qual,
-seq => $sequence,
-id => $id,
-primary_id => $id,
-desc => $fulldesc,
-alphabet => $alphabet
);
# if there wasn't one before, set the guessed type
$self->alphabet($seq->alphabet());
return $seq;
}
=head2 write_seq
Title : write_seq
Usage : $stream->write_seq(@seq)
Function: writes the $seq object into the stream
Returns : 1 for success and 0 for error
Args : Bio::Seq::SeqWithQuality or Bio::seq object
=cut
sub write_seq {
my ($self,@seq) = @_;
foreach my $seq (@seq) {
my $str = $seq->seq;
my $top = $seq->display_id();
if ($seq->can('desc') and my $desc = $seq->desc()) {
$desc =~ s/\n//g;
$top .= " $desc";
}
if(length($str) > 0) {
$str =~ s/(.{1,60})/$1\n/g;
} else {
$str = "\n";
}
$self->_print (">",$top,"\n",$str) or return;
}
$self->flush if $self->_flush_on_write && defined $self->_fh;
return 1;
}
=head2 write_qual
Title : write_qual
Usage : $stream->write_qual(@seq)
Function: writes the $seq object into the stream
Returns : 1 for success and 0 for error
Args : Bio::Seq::SeqWithQuality object
=cut
sub write_qual {
my ($self,@seq) = @_;
foreach my $seq (@seq) {
unless ($seq->isa("Bio::Seq::SeqWithQuality")){
warn("You can write FASTQ without supplying a Bio::Seq::SeqWithQuality object! ", ref($seq), "\n");
next;
}
my @qual = @{$seq->qual};
my $top = $seq->display_id();
if ($seq->can('desc') and my $desc = $seq->desc()) {
$desc =~ s/\n//g;
$top .= " $desc";
}
my $qual = "" ;
if(scalar(@qual) > 0) {
my $max = 60;
for (my $q = 0;$q<scalar(@qual);$q++){
$qual .= $qual[$q] . " ";
if(length($qual) > $max){
$qual .= "\n";
$max += 60;
}
}
} else {
$qual = "\n";
}
$self->_print (">",$top,"\n",$qual,"\n") or return;
}
return 1;
}
=head2 write_fastq
Title : write_fastq
Usage : $stream->write_fastq(@seq)
Function: writes the $seq object into the stream
Returns : 1 for success and 0 for error
Args : Bio::Seq::SeqWithQuality object
=cut
sub write_fastq {
my ($self,@seq) = @_;
foreach my $seq (@seq) {
unless ($seq->isa("Bio::Seq::SeqWithQuality")){
warn("You can write FASTQ without supplying a Bio::Seq::SeqWithQuality object! ", ref($seq), "\n");
next;
}
my $str = $seq->seq;
my @qual = @{$seq->qual};
my $top = $seq->display_id();
if ($seq->can('desc') and my $desc = $seq->desc()) {
$desc =~ s/\n//g;
$top .= " $desc";
}
if(length($str) == 0) {
$str = "\n";
}
my $qual = "" ;
if(scalar(@qual) > 0) {
for (my $q = 0;$q<scalar(@qual);$q++){
$qual .= chr($qual[$q] + 33);
}
} else {
$qual = "\n";
}
$self->_print ("\@",$top,"\n",$str,"\n") or return;
$self->_print ("+",$top,"\n",$qual,"\n") or return;
}
return 1;
}
1;
]]>