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Revision 1.2 - (download) (as text) (annotate)
Tue Jun 30 20:11:54 2009 UTC (10 years, 9 months ago) by parrello
Branch: MAIN
CVS Tags: rast_rel_2009_07_09
Changes since 1.1: +52 -1 lines
Additional functionality for sapling server.

#!/usr/bin/perl -w

#
# Copyright (c) 2003-2006 University of Chicago and Fellowship
# for Interpretations of Genomes. All Rights Reserved.
#
# This file is part of the SEED Toolkit.
#
# The SEED Toolkit is free software. You can redistribute
# it and/or modify it under the terms of the SEED Toolkit
# Public License.
#
# You should have received a copy of the SEED Toolkit Public License
# along with this program; if not write to the University of Chicago
# at info@ci.uchicago.edu or the Fellowship for Interpretation of
# Genomes at veronika@thefig.info or download a copy from
# http://www.theseed.org/LICENSE.TXT.
#

package SeedUtils;

    use strict;
    use Tracer;
    use base qw(Exporter);

    our @EXPORT = qw(create_fasta_record rev_comp);

=head1 SEED Utility Methods

=head2 Introduction

This is a simple utility package that performs functions useful for
bioinformatics, but that do not require access to the databases.

=head2 Public Methods

=head3 create_fasta_record

    my $fastaString = create_fasta_record($id, $comment, $sequence);

Create a FASTA record from the specified DNA or protein sequence. The
sequence will be split into 60-character lines, and the record will
include an identifier line and the trailing double-slash.

=over 4

=item id

ID for the sequence, to be placed at the beginning of the identifier
line.

=item comment (optional)

Comment text to place after the ID on the identifier line. If this parameter
is empty, undefined, or 0, no comment will be placed.

=item sequence

Sequence of letters to form into FASTA. For purposes of convenience, whitespace
characters in the sequence will be removed automatically.

=item RETURN

Returns the desired sequence in FASTA format.

=back

=cut

sub create_fasta_record {
    # Get the parameters.
    my ($id, $comment, $sequence) = @_;
    # Start with the ID.
    my $header = ">$id";
    # Add a comment, if any.
    if ($comment) {
        $header .= " $comment";
    }
    # Clean up the sequence.
    $sequence =~ s/\s+//g;
    # We need to format the sequence into 60-byte chunks. We use the infamous
    # grep-split trick. The split, because of the presence of the parentheses,
    # includes the matched delimiters in the output list. The grep strips out
    # the empty list items that appear between the so-called delimiters, since
    # the delimiters are what we want.
    my @chunks = grep { $_ } split /(.{1,60})/, $sequence;
    Trace(scalar(@chunks) . " chunks found in sequence of length " .
          length($sequence) . ".") if T(3);
    # Add the chunks and the trailer.
    my $retVal = join("\n", $header, @chunks, "//\n");
    # Return the result.
    return $retVal;
}

=head3 rev_comp

    my $revcmp = rev_comp($dna);

or

    rev_comp(\$dna);

Return the reverse complement of a DNA string.

=over 4

=item dna

Either a DNA string, or a reference to a DNA string.

=item RETURN

If the input is a DNA string, returns the reverse complement. If the
input is a reference to a DNA string, the string itself is reverse
complemented.

=back

=cut

sub rev_comp {
    # Get the parameters.
    my ($dna) = @_;
    # Determine how we were called.
    my ($retVal, $refMode);
    if (ref $dna eq 'SCALAR') {
        $retVal = lc reverse $dna;
        $refMode = 0;
    } else {
        $retVal = lc reverse $$dna;
        $refMode = 1;
    }
    # Now $retVal contains the reversed DNA string in all lower case, and
    # $refMode is TRUE iff the user passed in a reference. The following
    # translation step complements the string.
    $retVal =~ tr/acgtumrwsykbdhv/tgcaakywsrmvhdb/;
    # Return the result in the method corresponding to the way it came in.
    if ($refMode) {
        $$dna = $retVal;
        return;
    } else {
        return $retVal;
    }
}


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