Summary

Bio::AlignIO::fasta - FastA MSA Sequence input/output stream

Package variables

Included modules

Inherit

Bio::AlignIO

Synopsis

Do not use this module directly. Use it via the Bio::AlignIO class.

Description

This object can transform Bio::SimpleAlign objects to and from
fasta flat file databases. This is for the fasta sequence format NOT
FastA analysis program. To process the pairwise alignments from a
FastA (FastX, FastN, FastP, tFastA, etc) use the Bio::SearchIO module.

Methods

Methods description

 Title   : next_aln
 Usage   : $aln = $stream->next_aln()
 Function: returns the next alignment in the stream.
 Returns : Bio::Align::AlignI object - returns 0 on end of file
	    or on error
 Args    : NONE

 Title   : write_aln
 Usage   : $stream->write_aln(@aln)
 Function: writes the $aln object into the stream in fasta format
 Returns : 1 for success and 0 for error
 Args    : Bio::Align::AlignI object

Methods code

sub next_aln {

    my $self = shift;
    my $entry;
    my ($start,$end,$name,$seqname,$seq,$seqchar,$tempname,$tempdesc,
	%align,$desc);
    my $aln =  Bio::SimpleAlign->new();
    my $maxlen;
    while(defined ($entry = $self->_readline) ) {
	if( $entry =~ s/^>(\S+)\s*// ) {
	    $tempname  = $1;
	    chomp($entry);
	    $tempdesc  = $entry;
	    if( defined $name ) {
		# put away last name and sequence
		if( $name =~ /(\S+)\/(\d+)-(\d+)/ ) {
		    $seqname = $1;
		    $start = $2;
		    $end = $3;
		} else {
		    $seqname=$name;
		    $start = 1;
		    $end = length($seqchar); #ps 9/6/00
		}
#		print STDERR  "Going to add with $seqchar $seqname\n";
		$seq = new Bio::LocatableSeq('-seq'        =>$seqchar,
					     '-display_id' =>$seqname,
					     '-description'=>$desc,
					     '-start'      =>$start,
					     '-end'        =>$end,
					     );
		$aln->add_seq($seq);
	    }
	    $desc = $tempdesc;	
	    $name = $tempname;
	    $desc = $entry;
	    $seqchar  = "";
	    next;
	}
	$entry =~ s/[^A-Za-z\.\-]//g;
	$seqchar .= $entry;	
    }
#
#  Next two lines are to silence warnings that
#  otherwise occur at EOF when using <$fh>

   if (!defined $name) {$name="";}
   if (!defined $seqchar) {$seqchar="";}

#  Put away last name and sequence
    if( $name =~ /(\S+)\/(\d+)-(\d+)/ ) {
	$seqname = $1;
	$start = $2;
	$end = $3;
    } else {
	$seqname=$name;
	$start = 1;
	$end = length($seqchar);   #ps 9/6/00
#	$end = length($align{$name});
    }


#  If $end <= 0, we have either reached the end of
#  file in <> or we have encountered some other error
#
   if ($end <= 0) { undef $aln; return $aln;}

# This logic now also reads empty lines at the 
# end of the file. Skip this is seqchar and seqname is null

    if( length($seqchar) == 0 && length($seqname) == 0 ) {
	# skip
    } else {
#	print STDERR "end to add with $seqchar $seqname\n";
	$seq = new Bio::LocatableSeq('-seq'        => $seqchar,
				     '-display_id' => $seqname,
				     '-description'=> $desc,
				     '-start'      => $start,
				     '-end'        => $end,
				     );
	
	$aln->add_seq($seq);
    }
    my $alnlen = $aln->length;
    foreach my $seq ( $aln->each_seq ) {
	if( $seq->length < $alnlen ) {
	    my ($diff) = ($alnlen - $seq->length);
	    $seq->seq( $seq->seq() . "-" x $diff);
	}
    }

    return $aln;

}

sub write_aln {

    my ($self,@aln) = @_;
    my ($seq,$desc,$rseq,$name,$count,$length,$seqsub);

    foreach my $aln (@aln) {
	if( ! $aln || ! $aln->isa('Bio::Align::AlignI')  ) { 
	    $self->warn("Must provide a Bio::Align::AlignI object when calling write_aln");
	    next;
	}
	foreach $rseq ( $aln->each_seq() ) {
	    $name = $aln->displayname($rseq->get_nse());
	    $seq  = $rseq->seq();
	    $desc = $rseq->description || '';
	    $self->_print (">$name $desc\n") or return ;	
	    $count =0;
	    $length = length($seq);
	    while( ($count * 60 ) < $length ) {
		$seqsub = substr($seq,$count*60,60);
		$self->_print ("$seqsub\n") or return ;
		$count++;
	    }
	}
    }
    $self->flush if $self->_flush_on_write && defined $self->_fh;
    return 1;

}

General documentation

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/

Email: schattner@alum.mit.edu

The rest of the documentation details each of the object
methods. Internal methods are usually preceded with a _