org.moeaframework.core.operator.permutation
Class PMX

java.lang.Object
  org.moeaframework.core.operator.permutation.PMX

All Implemented Interfaces:

Variation

public class PMX
extends Object
implements Variation

Partially mapped crossover (PMX) operator. PMX is similar to two-point crossover, but includes a repair operator to ensure the offspring are valid permutations.

This variation operator is type-safe.

References:

1. Goldberg, D. and Lingle, R. Jr. "Alleles, Loci, and the Traveling Salesman Problem." Proceedings of the 1st International Conference on Genetic Algorithms and Their Applications. 1985.

Constructor Summary

PMX(double probability)
Constructs a PMX operator with the specified probability.

Method Summary

static void	evolve(Permutation p1, Permutation p2) Evolves the specified permutations using the PMX operator.
Solution[]	evolve(Solution[] parents) Evolves one or more parent solutions (specified by getArity) and produces one or more child solutions.
int	getArity() Returns the number of solutions that must be supplied to the evolve method.

Methods inherited from class java.lang.Object

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

Constructor Detail

PMX

public PMX(double probability)

Constructs a PMX operator with the specified probability.

Parameters:

probability - the probability of applying this operator

Method Detail

evolve

public static void evolve(Permutation p1,
                          Permutation p2)

Evolves the specified permutations using the PMX operator.

Parameters:

p1 - the first permutation

p2 - the second permutation

Throws:

VariationException - if the permutations are not the same size

evolve

public Solution[] evolve(Solution[] parents)

Description copied from interface: Variation

Evolves one or more parent solutions (specified by getArity) and produces one or more child solutions. By contract, the parents must not be modified. The copy constructor should be used to create copies of the parents with these copies subsequently modified.

Specified by:

evolve in interface Variation

Parameters:

parents - the array of parent solutions

Returns:

an array of child solutions

getArity

public int getArity()

Description copied from interface: Variation

Returns the number of solutions that must be supplied to the evolve method.

Specified by:

getArity in interface Variation

Returns:

the number of solutions that must be supplied to the evolve method