view release on metacpan or  search on metacpan

lib/Algorithm/Evolutionary/Fitness/Trap.pm  view on Meta::CPAN

package Algorithm::Evolutionary::Fitness::Trap; # -*- cperl -*-

use strict; 
use warnings;
use Carp qw(croak);

our $VERSION = '3.2';

use lib qw(../../.. ../.. .. ../../../../lib);

use base qw(Algorithm::Evolutionary::Fitness::String);


=head1 NAME

Algorithm::Evolutionary::Fitness::Trap - 'Trap' fitness function for evolutionary algorithms

=head1 SYNOPSIS

    my $number_of_bits = 5;
    my $a = $number_of_bits -1; # Usual default values follow
    my $b = $number_of_bits;
    my $z = $number_of_bits -1;
    my $trap = Algorithm::Evolutionary::Fitness::Trap->new( $number_of_bits, $a, $b, $z );

# Equivalent to

    $trap = Algorithm::Evolutionary::Fitness::Trap->new( $number_of_bits );

    my $chromosome = "10101111110000";
    my $fitness = $trap->apply( $chromosome );

=head1 DESCRIPTION

Trap functions act as "yucky" or deceptive for evolutionary algorithms;
they "trap" population into going to easier, but local, optima.

=head1 METHODS


=head2 new( $number_of_bits, [$a = $number_of_bits -1, $b = $number_of_bits, $z=$number_of_bits-1])

Creates a new instance of the problem, with the said number of bits
and traps. Uses default values from C<$number_of_bits> if needed

=cut

sub new {
  my $class = shift;
  my $number_of_bits = shift || croak "Need non-null number of bits\n";
  my $a = shift || $number_of_bits - 1;
  my $b = shift || $number_of_bits;
  my $z = shift || $number_of_bits - 1;

  croak "Z too big" if $z >= $number_of_bits;
  croak "Z too small" if $z < 1;
  croak "A must be less than B" if $a > $b;
  my $self = $class->SUPER::new();
  bless $self, $class;
  $self->initialize();
  $self->{'l'} = $number_of_bits;
  $self->{'a'} = $a;
  $self->{'b'} = $b;
  $self->{'z'} = $z;
  return $self;
}

=head2 _really_apply