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: 799857 $ $Date: 2009-08-01 09:07:12 -0400 (Sat, 01 Aug 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 }