001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.commons.math.genetics; 018 019 import java.util.ArrayList; 020 import java.util.List; 021 022 /** 023 * Mutation for {@link BinaryChromosome}s. Randomly changes one gene. 024 * 025 * @version $Revision: 811685 $ $Date: 2009-09-05 13:36:48 -0400 (Sat, 05 Sep 2009) $ 026 * @since 2.0 027 */ 028 public class BinaryMutation implements MutationPolicy { 029 030 /** 031 * Mutate the given chromosome. Randomly changes one gene. 032 * @param original the original chromosome. 033 * @return the mutated chromomsome. 034 */ 035 public Chromosome mutate(Chromosome original) { 036 if (!(original instanceof BinaryChromosome)) { 037 throw new IllegalArgumentException("Binary mutation works on BinaryChromosome only."); 038 } 039 040 BinaryChromosome origChrom = (BinaryChromosome) original; 041 List<Integer> newRepr = new ArrayList<Integer>(origChrom.getRepresentation()); 042 043 // randomly select a gene 044 int geneIndex = GeneticAlgorithm.getRandomGenerator().nextInt(origChrom.getLength()); 045 // and change it 046 newRepr.set(geneIndex, origChrom.getRepresentation().get(geneIndex) == 0 ? 1 : 0); 047 048 Chromosome newChrom = origChrom.newFixedLengthChromosome(newRepr); 049 return newChrom; 050 } 051 052 }