/*
* Encog(tm) Core v2.5 - Java Version
* http://www.heatonresearch.com/encog/
* http://code.google.com/p/encog-java/
* Copyright 2008-2010 Heaton Research, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* For more information on Heaton Research copyrights, licenses
* and trademarks visit:
* http://www.heatonresearch.com/copyright
*/
package org.encog.solve.genetic.mutate;
import org.encog.solve.genetic.genes.Gene;
import org.encog.solve.genetic.genome.Chromosome;
/**
* A simple mutation where genes are shuffled.
* This mutation will not produce repeated genes.
*/
public class MutateShuffle implements Mutate {
/**
* Perform a shuffle mutation.
* @param chromosome The chromosome to mutate.
*/
public void performMutation(final Chromosome chromosome) {
final int length = chromosome.getGenes().size();
int iswap1 = (int) (Math.random() * length);
int iswap2 = (int) (Math.random() * length);
// can't be equal
if (iswap1 == iswap2) {
// move to the next, but
// don't go out of bounds
if (iswap1 > 0) {
iswap1--;
} else {
iswap1++;
}
}
// make sure they are in the right order
if (iswap1 > iswap2) {
final int temp = iswap1;
iswap1 = iswap2;
iswap2 = temp;
}
final Gene gene1 = chromosome.getGenes().get(iswap1);
final Gene gene2 = chromosome.getGenes().get(iswap2);
// remove the two genes
chromosome.getGenes().remove(gene1);
chromosome.getGenes().remove(gene2);
// insert them back in, reverse order
chromosome.getGenes().add(iswap1, gene2);
chromosome.getGenes().add(iswap2, gene1);
}
}