[Omaha.pm] All possible DNA sequences that are 5-7 bases long

[jay at jays.net]

Enjoy,    :)

j



#!/usr/bin/perl

# http://www.perl.com/pub/a/2005/06/16/iterators.html
# {slightly modified by jhannah 20081124)

my @DNA = qw/A C T G/;
my $seq = gen_permutate(5, 7, @DNA);
while ( my $strand = $seq->() ) {
    print "$strand\n";
}

sub gen_permutate {
    my ($min, $max, @list) = @_;
    my @curr = (0) x $min;
    return sub {
        if ( (join '', map { $list[ $_ ] } @curr) eq $list[ -1 ] x @curr )
{
            @curr = (0) x (@curr + 1);
        }
        else {
            my $pos = @curr;
            while ( --$pos > -1 ) {
                ++$curr[ $pos ], last if $curr[ $pos ] < $#list;
                $curr[ $pos ] = 0;
            }
        }
        return undef if @curr > $max;
        return join '', map { $list[ $_ ] } @curr;
    };
}