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 operator for {@link RandomKey}s. Changes a randomly chosen element
27 * of the array representation to a random value uniformly distributed in [0,1].
28 *
29 * @since 2.0
30 */
31 public class RandomKeyMutation implements MutationPolicy {
32
33 /**
34 * {@inheritDoc}
35 *
36 * @throws MathIllegalArgumentException if <code>original</code> is not a {@link RandomKey} instance
37 */
38 @Override
39 public Chromosome mutate(final Chromosome original) throws MathIllegalArgumentException {
40 if (!(original instanceof RandomKey<?>)) {
41 throw new MathIllegalArgumentException(LocalizedFormats.RANDOMKEY_MUTATION_WRONG_CLASS,
42 original.getClass().getSimpleName());
43 }
44
45 RandomKey<?> originalRk = (RandomKey<?>) original;
46 List<Double> repr = originalRk.getRepresentation();
47 int rInd = GeneticAlgorithm.getRandomGenerator().nextInt(repr.size());
48
49 List<Double> newRepr = new ArrayList<> (repr);
50 newRepr.set(rInd, GeneticAlgorithm.getRandomGenerator().nextDouble());
51
52 return originalRk.newFixedLengthChromosome(newRepr);
53 }
54 }