J. J. Merelo-Guervós > Algorithm-Evolutionary-0.78 > Algorithm::Evolutionary::Op::Mutation

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Module Version: 3.1   Source   Latest Release: Algorithm-Evolutionary-0.80

NAME ^

Algorithm::Evolutionary::Op::Mutation - BitFlip mutation, changes several bits in a bitstring, depending on the probability

SYNOPSIS ^

  use Algorithm::Evolutionary::Op::Mutation;

  my $xmlStr=<<EOC;
  <op name='Mutation' type='unary' rate='2'>
    <param name='probability' value='0.5' />
  </op>
  EOC
  my $ref = XMLin($xmlStr);

  my $op = Algorithm::Evolutionary::Op::->fromXML( $ref );
  print $op->asXML(), "\n*Arity ->", $op->arity(), "\n";

  #Create from scratch
  my $op = new Algorithm::Evolutionary::Op::Mutation (0.5 ); 

  #All options
  my $priority = 1;
  my $mutation = new Algorithm::Evolutionary::Op::Mutation 1/$length, $priority;

Base Class ^

Algorithm::Evolutionary::Op::Base

DESCRIPTION ^

Mutation operator for a GA

METHODS ^

new( [$mutation_rate] [, $operator_probability] )

Creates a new mutation operator with a bitflip application rate, which defaults to 0.5, and an operator application rate (general for all ops), which defaults to 1. Application rate will be converted in runtime to application probability, which will eventually depend on the rates of all the other operators. For instance, if this operator's rate is one and there's another with rate=4, probability will be 20% for this one and 80% for the other; 1 in 5 new individuals will be generated using this and the rest using the other one.

create( [$operator_probability] )

Creates a new mutation operator with an application rate. Rate defaults to 0.5 (which is rather high, you should not rely on it).

Called create to distinguish from the classwide ctor, new. It just makes simpler to create a Mutation Operator

apply( $chromosome )

Applies mutation operator to a "Chromosome", a bitstring, really. Can be applied only to victims with the _str instance variable; it checks before application that the operand is of type Algorithm::Evolutionary::Individual::BitString. It returns the victim.

Copyright ^

  This file is released under the GPL. See the LICENSE file included in this distribution,
  or go to http://www.fsf.org/licenses/gpl.txt

  CVS Info: $Date: 2009/09/13 12:49:04 $ 
  $Header: /cvsroot/opeal/Algorithm-Evolutionary/lib/Algorithm/Evolutionary/Op/Mutation.pm,v 3.1 2009/09/13 12:49:04 jmerelo Exp $ 
  $Author: jmerelo $ 
  $Revision: 3.1 $
  $Name $
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