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.math4.legacy.genetics; 18 19 import java.util.ArrayList; 20 import java.util.List; 21 22 import org.apache.commons.math4.legacy.exception.MathIllegalArgumentException; 23 import org.apache.commons.math4.legacy.exception.util.LocalizedFormats; 24 25 /** 26 * Mutation for {@link BinaryChromosome}s. Randomly changes one gene. 27 * 28 * @since 2.0 29 */ 30 public class BinaryMutation implements MutationPolicy { 31 32 /** 33 * Mutate the given chromosome. Randomly changes one gene. 34 * 35 * @param original the original chromosome. 36 * @return the mutated chromosome. 37 * @throws MathIllegalArgumentException if <code>original</code> is not an instance of {@link BinaryChromosome}. 38 */ 39 @Override 40 public Chromosome mutate(Chromosome original) throws MathIllegalArgumentException { 41 if (!(original instanceof BinaryChromosome)) { 42 throw new MathIllegalArgumentException(LocalizedFormats.INVALID_BINARY_CHROMOSOME); 43 } 44 45 BinaryChromosome origChrom = (BinaryChromosome) original; 46 List<Integer> newRepr = new ArrayList<>(origChrom.getRepresentation()); 47 48 // randomly select a gene 49 int geneIndex = GeneticAlgorithm.getRandomGenerator().nextInt(origChrom.getLength()); 50 // and change it 51 newRepr.set(geneIndex, origChrom.getRepresentation().get(geneIndex) == 0 ? 1 : 0); 52 53 return origChrom.newFixedLengthChromosome(newRepr); 54 } 55 }