1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 package org.apache.commons.math.genetics; 18 19 import java.util.ArrayList; 20 import java.util.List; 21 22 /** 23 * Mutation for {@link BinaryChromosome}s. Randomly changes one gene. 24 * 25 * @version $Revision: 811685 $ $Date: 2009-09-05 19:36:48 +0200 (sam. 05 sept. 2009) $ 26 * @since 2.0 27 */ 28 public class BinaryMutation implements MutationPolicy { 29 30 /** 31 * Mutate the given chromosome. Randomly changes one gene. 32 * @param original the original chromosome. 33 * @return the mutated chromomsome. 34 */ 35 public Chromosome mutate(Chromosome original) { 36 if (!(original instanceof BinaryChromosome)) { 37 throw new IllegalArgumentException("Binary mutation works on BinaryChromosome only."); 38 } 39 40 BinaryChromosome origChrom = (BinaryChromosome) original; 41 List<Integer> newRepr = new ArrayList<Integer>(origChrom.getRepresentation()); 42 43 // randomly select a gene 44 int geneIndex = GeneticAlgorithm.getRandomGenerator().nextInt(origChrom.getLength()); 45 // and change it 46 newRepr.set(geneIndex, origChrom.getRepresentation().get(geneIndex) == 0 ? 1 : 0); 47 48 Chromosome newChrom = origChrom.newFixedLengthChromosome(newRepr); 49 return newChrom; 50 } 51 52 } 53
