/*
* 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.crossover;
import java.util.HashSet;
import java.util.Set;
import org.encog.solve.genetic.genes.Gene;
import org.encog.solve.genetic.genome.Chromosome;
/**
* A simple cross over where genes are simply "spliced". Genes are not allowed
* to repeat.
*/
public class SpliceNoRepeat implements Crossover {
/**
* Get a list of the genes that have not been taken before. This is useful
* if you do not wish the same gene to appear more than once in a
* chromosome.
*
* @param source
* The pool of genes to select from.
* @param taken
* An array of the taken genes.
* @return Those genes in source that are not taken.
*/
private static Gene getNotTaken(final Chromosome source,
final Set<Gene> taken) {
for (final Gene trial : source.getGenes()) {
if (!taken.contains(trial)) {
taken.add(trial);
return trial;
}
}
return null;
}
/**
* The cut length.
*/
private final int cutLength;
/**
* Construct a splice crossover.
*
* @param cutLength
* The cut length.
*/
public SpliceNoRepeat(final int cutLength) {
this.cutLength = cutLength;
}
/**
* Assuming this chromosome is the "mother" mate with the passed in
* "father".
*
* @param father
* The father.
* @param offspring1
* Returns the first offspring
* @param offspring2
* Returns the second offspring.
*/
public void mate(final Chromosome mother, final Chromosome father,
final Chromosome offspring1, final Chromosome offspring2) {
final int geneLength = father.getGenes().size();
// the chromosome must be cut at two positions, determine them
final int cutpoint1 = (int) (Math.random() * (geneLength - this.cutLength));
final int cutpoint2 = cutpoint1 + this.cutLength;
// keep track of which genes have been taken in each of the two
// offspring, defaults to false.
final Set<Gene> taken1 = new HashSet<Gene>();
final Set<Gene> taken2 = new HashSet<Gene>();
// handle cut section
for (int i = 0; i < geneLength; i++) {
if (!((i < cutpoint1) || (i > cutpoint2))) {
offspring1.getGene(i).copy(father.getGene(i));
offspring2.getGene(i).copy(mother.getGene(i));
taken1.add(father.getGene(i));
taken2.add(mother.getGene(i));
}
}
// handle outer sections
for (int i = 0; i < geneLength; i++) {
if ((i < cutpoint1) || (i > cutpoint2)) {
offspring1.getGene(i).copy(
SpliceNoRepeat.getNotTaken(mother, taken1));
offspring2.getGene(i).copy(
SpliceNoRepeat.getNotTaken(father, taken2));
}
}
}
}