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 import org.apache.commons.math.MathRuntimeException;
023 import org.apache.commons.math.exception.util.LocalizedFormats;
024
025 /**
026 * Mutation operator for {@link RandomKey}s. Changes a randomly chosen element
027 * of the array representation to a random value uniformly distributed in [0,1].
028 *
029 * @since 2.0
030 * @version $Revision: 983921 $ $Date: 2010-08-10 12:46:06 +0200 (mar. 10 ao??t 2010) $
031 */
032 public class RandomKeyMutation implements MutationPolicy {
033
034 /**
035 * {@inheritDoc}
036 *
037 * @throws IllegalArgumentException if <code>original</code> is not a
038 * {@link RandomKey} instance
039 */
040 public Chromosome mutate(Chromosome original) {
041 if (!(original instanceof RandomKey<?>)) {
042 throw MathRuntimeException.createIllegalArgumentException(
043 LocalizedFormats.RANDOMKEY_MUTATION_WRONG_CLASS,
044 original.getClass().getSimpleName());
045 }
046
047 RandomKey<?> originalRk = (RandomKey<?>) original;
048 List<Double> repr = originalRk.getRepresentation();
049 int rInd = GeneticAlgorithm.getRandomGenerator().nextInt(repr.size());
050
051 List<Double> newRepr = new ArrayList<Double> (repr);
052 newRepr.set(rInd, GeneticAlgorithm.getRandomGenerator().nextDouble());
053
054 return originalRk.newFixedLengthChromosome(newRepr);
055 }
056
057 }