###########################
#from Perl Cookbook 2.10
#take in a hash and via a weighted random, pick one of the 
#keys based on the value and return it
###########################
sub weighted_rand {
    my %dist = @_;
    my ($key, $weight);
    my $rand;

    while (1) { # to avoid floating point inaccuracies
        $rand = rand;
        while ( ($key, $weight) = each %dist ) {
            return $key if ($rand -= $weight) < 0;
        }
    }
}
###########################