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
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