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; 023 024 /** 025 * Mutation operator for {@link RandomKey}s. Changes a randomly chosen element 026 * of the array representation to a random value uniformly distributed in [0,1]. 027 * 028 * @since 2.0 029 * @version $Revision: 811685 $ $Date: 2009-09-05 13:36:48 -0400 (Sat, 05 Sep 2009) $ 030 */ 031 public class RandomKeyMutation implements MutationPolicy { 032 033 /** 034 * {@inheritDoc} 035 * 036 * @throws IllegalArgumentException if <code>original</code> is not a 037 * {@link RandomKey} instance 038 */ 039 public Chromosome mutate(Chromosome original) { 040 if (!(original instanceof RandomKey<?>)) { 041 throw MathRuntimeException.createIllegalArgumentException( 042 "RandomKeyMutation works only with RandomKeys, got " + 043 original.getClass().getSimpleName()); 044 } 045 046 RandomKey<?> originalRk = (RandomKey<?>) original; 047 List<Double> repr = originalRk.getRepresentation(); 048 int rInd = GeneticAlgorithm.getRandomGenerator().nextInt(repr.size()); 049 050 List<Double> newRepr = new ArrayList<Double> (repr); 051 newRepr.set(rInd, GeneticAlgorithm.getRandomGenerator().nextDouble()); 052 053 return originalRk.newFixedLengthChromosome(newRepr); 054 } 055 056 }