NAME

Algorithm::Evolutionary::Simple - Run a simple, canonical evolutionary algorithm in Perl

VERSION

This document describes Algorithm::Evolutionary::Simple version 0.1.2

SYNOPSIS

  use Algorithm::Evolutionary::Simple qw( random_chromosome max_ones max_ones_fast
                                        get_pool_roulette_wheel get_pool_binary_tournament produce_offspring single_generation);

  my @population;
  my %fitness_of;
  for (my $i = 0; $i < $number_of_strings; $i++) {
   $population[$i] = random_chromosome( $length);
   $fitness_of{$population[$i]} = max_ones( $population[$i] );
  }

  my @best;
  my $generations=0;
  do {
    my @pool;
    if ( $generations % 2 == 1 ) {
      get_pool_roulette_wheel( \@population, \%fitness_of, $number_of_strings );
    } else {
     get_pool_binary_tournament( \@population, \%fitness_of, $number_of_strings );
    }
    my @new_pop = produce_offspring( \@pool, $number_of_strings/2 );
    for my $p ( @new_pop ) {
        if ( !$fitness_of{$p} ) {
           $fitness_of{$p} = max_ones( $p );
        }
    }
    @best = rnkeytop { $fitness_of{$_} } $number_of_strings/2 => @population;
    @population = (@best, @new_pop);
    print "Best so far $best[0] with fitness $fitness_of{$best[0]}\n";
  } while ( ( $generations++ < $number_of_generations ) and ($fitness_of{$best[0]} != $length ));

DESCRIPTION

Assorted functions needed by an evolutionary algorithm, mainly for demos and simple clients.

INTERFACE

random_chromosome( $length )

Creates a binary chromosome, with uniform distribution of 0s and 1s, and returns it as a string.

max_ones( $string )

Classical function that returns the number of ones in a binary string.

max_ones_fast( $string )

Faster implementation of max_ones.

spin($wheel, $slots )

Mainly for internal use, $wheel has the normalized probability, and $slots the number of individuals to return.

single_generation( $population_arrayref, $fitness_of_hashref )

Applies all steps to arrive to a new generation, except evaluation. Keeps the two best for the next generation.

get_pool_roulette_wheel( $population_arrayref, $fitness_of_hashref, $how_many_I_need )

Obtains a pool of new chromosomes using fitness_proportional selection

get_pool_binary_tournament( $population_arrayref, $fitness_of_hashref, $how_many_I_need )

Obtains a pool of new chromosomes using binary tournament, a greedier method.

produce_offspring( $population_hashref, $how_many_I_need )

Uses mutation first and then crossover to obtain a new population

mutate( $string )

Bitflips a a single point in the binary string

crossover( $one_string, $another_string )

Applies two-point crossover to both strings, returning them changed

DIAGNOSTICS

Will complain if some argument is missing.

Algorithm::Evolutionary::Simple requires no configuration files or environment variables.

DEPENDENCIES

Sort::Key::Top for efficient sorting.

SEE ALSO

There are excellent evolutionary algorithm libraries out there; see for instance AI::Genetic::Pro

BUGS AND LIMITATIONS

It's intended for simplicity, not flexibility. If you want a full-featured evolutionary algorithm library, check Algorithm::Evolutionary

Please report any bugs or feature requests to bug-algorithm-evolutionary-simple@rt.cpan.org, or through the web interface at http://rt.cpan.org.

AUTHOR

JJ Merelo <jj@merelo.net>

LICENCE AND COPYRIGHT

Copyright (c) 2011, JJ Merelo <jj@merelo.net>. All rights reserved.

This module is free software; you can redistribute it and/or modify it under the GPL v3 licence.

DISCLAIMER OF WARRANTY

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

cpanm Algorithm::Evolutionary::Simple

perl -MCPAN -e shell
install Algorithm::Evolutionary::Simple