Module io.jenetics.base

Package io.jenetics

Class Recombinator<G extends Gene<?,G>,C extends Comparable<? super C>>

java.lang.Object

io.jenetics.AbstractAlterer<G,C>

io.jenetics.Recombinator<G,C>

All Implemented Interfaces:

Alterer<G,C>

Direct Known Subclasses:

CombineAlterer, Crossover, TreeCrossover

public abstract class Recombinator<G extends Gene<?,G>,C extends Comparable<? super C>>
extends AbstractAlterer<G,C>

An enhanced genetic algorithm (EGA) combine elements of existing solutions in order to create a new solution, with some of the properties of each parent. Recombination creates a new chromosome by combining parts of two (or more) parent chromosomes. This combination of chromosomes can be made by selecting one or more crossover points, splitting these chromosomes on the selected points, and merge those portions of different chromosomes to form new ones.

The recombination probability P(r) determines the probability that a given individual (genotype, not gene) of a population is selected for recombination. The (mean) number of changed individuals depend on the concrete implementation and can be vary from P(r)·N_G to P(r)·N_G·O_R, where O_R is the order of the recombination, which is the number of individuals involved int the recombine(io.jenetics.util.MSeq<io.jenetics.Phenotype<G, C>>, int[], long) method.

Since:

1.0

Version:

6.0

Field Summary

Fields inherited from class io.jenetics.AbstractAlterer

_probability

Fields inherited from interface io.jenetics.Alterer

DEFAULT_ALTER_PROBABILITY

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	Recombinator(double probability, int order)	Constructs an alterer with a given recombination probability.

Method Summary

Modifier and Type	Method	Description
final AltererResult<G,C>	alter(Seq<Phenotype<G,C>> population, long generation)	Alters (recombine) a given population.
int	order()	Return the number of individuals involved in the recombine(MSeq, int[], long) step.
protected abstract int	recombine(MSeq<Phenotype<G,C>> population, int[] individuals, long generation)	Recombination template method.

Methods inherited from class io.jenetics.AbstractAlterer

probability

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface io.jenetics.Alterer

andThen, compose

Constructor Details

Recombinator

protected Recombinator(double probability,
 int order)

Constructs an alterer with a given recombination probability.

Parameters:

probability - The recombination probability.

order - the number of individuals involved in the recombine(MSeq, int[], long) step

Throws:

IllegalArgumentException - if the probability is not in the valid range of [0, 1] or the given order is smaller than two.

Method Details

order

public int order()

Return the number of individuals involved in the recombine(MSeq, int[], long) step.

Returns:

the number of individuals involved in the recombination step.

alter

public final AltererResult<G,C> alter(Seq<Phenotype<G,C>> population,
 long generation)

Description copied from interface: Alterer

Alters (recombine) a given population. If the population is empty, nothing is altered. The altered population is part of the returned AlterResult object.

Parameters:

population - The Population to be altered. If the population is null or empty, nothing is altered.

generation - the date of birth (generation) of the altered phenotypes.

Returns:

the alter-result object, which contains the altered population and the alteration counts

recombine

protected abstract int recombine(MSeq<Phenotype<G,C>> population,
 int[] individuals,
 long generation)

Recombination template method. This method is called 0 to n times. It is guaranteed that this method is only called by one thread.

Parameters:

population - the population to recombine

individuals - the array with the indexes of the individuals which are involved in the recombination step. The length of the array is order(). The first individual is the primary individual.

generation - the current generation.

Returns:

the number of genes that has been altered.