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.math3.genetics; 018 019 import java.util.ArrayList; 020 import java.util.List; 021 022 import org.apache.commons.math3.exception.MathIllegalArgumentException; 023 import org.apache.commons.math3.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 $Id: RandomKeyMutation.java 1416643 2012-12-03 19:37:14Z tn $ 031 */ 032 public class RandomKeyMutation implements MutationPolicy { 033 034 /** 035 * {@inheritDoc} 036 * 037 * @throws MathIllegalArgumentException if <code>original</code> is not a {@link RandomKey} instance 038 */ 039 public Chromosome mutate(final Chromosome original) throws MathIllegalArgumentException { 040 if (!(original instanceof RandomKey<?>)) { 041 throw new MathIllegalArgumentException(LocalizedFormats.RANDOMKEY_MUTATION_WRONG_CLASS, 042 original.getClass().getSimpleName()); 043 } 044 045 RandomKey<?> originalRk = (RandomKey<?>) original; 046 List<Double> repr = originalRk.getRepresentation(); 047 int rInd = GeneticAlgorithm.getRandomGenerator().nextInt(repr.size()); 048 049 List<Double> newRepr = new ArrayList<Double> (repr); 050 newRepr.set(rInd, GeneticAlgorithm.getRandomGenerator().nextDouble()); 051 052 return originalRk.newFixedLengthChromosome(newRepr); 053 } 054 055 }