1dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond/* 2dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * Licensed to the Apache Software Foundation (ASF) under one or more 3dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * contributor license agreements. See the NOTICE file distributed with 4dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * this work for additional information regarding copyright ownership. 5dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * The ASF licenses this file to You under the Apache License, Version 2.0 6dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * (the "License"); you may not use this file except in compliance with 7dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * the License. You may obtain a copy of the License at 8dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * 9dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * http://www.apache.org/licenses/LICENSE-2.0 10dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * 11dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * Unless required by applicable law or agreed to in writing, software 12dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * distributed under the License is distributed on an "AS IS" BASIS, 13dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * See the License for the specific language governing permissions and 15dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * limitations under the License. 16dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond */ 17dee0849a9704d532af0b550146cbafbaa6ee1d19Raymondpackage org.apache.commons.math.genetics; 18dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond 19dee0849a9704d532af0b550146cbafbaa6ee1d19Raymondimport java.util.ArrayList; 20dee0849a9704d532af0b550146cbafbaa6ee1d19Raymondimport java.util.List; 21dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond 22dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond 23dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond/** 24dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * One point crossover policy. A random crossover point is selected and the 25dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * first part from each parent is copied to the corresponding child, and the 26dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * second parts are copied crosswise. 27dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * 28dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * Example: 29dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * <pre> 30dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * -C- denotes a crossover point 31dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * -C- -C- 32dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * p1 = (1 0 1 0 0 1 | 0 1 1) X p2 = (0 1 1 0 1 0 | 1 1 1) 33dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * \------------/ \-----/ \------------/ \-----/ 34dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * || (*) || (**) 35dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * VV (**) VV (*) 36dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * /------------\ /-----\ /------------\ /-----\ 37dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * c1 = (1 0 1 0 0 1 | 1 1 1) X p2 = (0 1 1 0 1 0 | 0 1 1) 38dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * </pre> 39dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * 40dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * This policy works only on {@link AbstractListChromosome}, and therefore it 41dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * is parametrized by T. Moreover, the chromosomes must have same lengths. 42dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * 43dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * @param <T> generic type of the {@link AbstractListChromosome}s for crossover 44dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * @since 2.0 45dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * @version $Revision: 903046 $ $Date: 2010-01-26 03:07:26 +0100 (mar. 26 janv. 2010) $ 46dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * 47dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond */ 48dee0849a9704d532af0b550146cbafbaa6ee1d19Raymondpublic class OnePointCrossover<T> implements CrossoverPolicy { 49dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond 50dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond /** 51dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * Performs one point crossover. A random crossover point is selected and the 52dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * first part from each parent is copied to the corresponding child, and the 53dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * second parts are copied crosswise. 54dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * 55dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * Example: 56dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * -C- denotes a crossover point 57dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * -C- -C- 58dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * p1 = (1 0 1 0 0 1 | 0 1 1) X p2 = (0 1 1 0 1 0 | 1 1 1) 59dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * \------------/ \-----/ \------------/ \-----/ 60dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * || (*) || (**) 61dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * VV (**) VV (*) 62dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * /------------\ /-----\ /------------\ /-----\ 63dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * c1 = (1 0 1 0 0 1 | 1 1 1) X p2 = (0 1 1 0 1 0 | 0 1 1) 64dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * 65dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * @param first first parent (p1) 66dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * @param second second parent (p2) 67dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * @return pair of two children (c1,c2) 68dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond */ 69dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond @SuppressWarnings("unchecked") // OK because of instanceof checks 70dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond public ChromosomePair crossover(Chromosome first, Chromosome second) { 71dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond if (! (first instanceof AbstractListChromosome<?> && second instanceof AbstractListChromosome<?>)) { 72dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond throw new IllegalArgumentException("One point crossover works on FixedLengthChromosomes only."); 73dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond } 74dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond return crossover((AbstractListChromosome<T>) first, (AbstractListChromosome<T>) second); 75dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond } 76dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond 77dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond 78dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond /** 79dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * Helper for {@link #crossover(Chromosome, Chromosome)}. Performs the actual crossover. 80dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * 81dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * @param first the first chromosome. 82dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * @param second the second chromosome. 83dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond * @return the pair of new chromosomes that resulted from the crossover. 84dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond */ 85dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond private ChromosomePair crossover(AbstractListChromosome<T> first, AbstractListChromosome<T> second) { 86dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond int length = first.getLength(); 87dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond if (length != second.getLength()) 88dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond throw new IllegalArgumentException("Both chromosomes must have same lengths."); 89dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond 90dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond // array representations of the parents 91dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond List<T> parent1Rep = first.getRepresentation(); 92dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond List<T> parent2Rep = second.getRepresentation(); 93dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond // and of the children 94dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond ArrayList<T> child1Rep = new ArrayList<T> (first.getLength()); 95dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond ArrayList<T> child2Rep = new ArrayList<T> (second.getLength()); 96dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond 97dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond // select a crossover point at random (0 and length makes no sense) 98dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond int crossoverIndex = 1 + (GeneticAlgorithm.getRandomGenerator().nextInt(length-2)); 99dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond 100dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond // copy the first part 101dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond for (int i = 0; i < crossoverIndex; i++) { 102dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond child1Rep.add(parent1Rep.get(i)); 103dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond child2Rep.add(parent2Rep.get(i)); 104dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond } 105dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond // and switch the second part 106dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond for (int i = crossoverIndex; i < length; i++) { 107dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond child1Rep.add(parent2Rep.get(i)); 108dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond child2Rep.add(parent1Rep.get(i)); 109dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond } 110dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond 111dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond return new ChromosomePair( 112dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond first.newFixedLengthChromosome(child1Rep), 113dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond second.newFixedLengthChromosome(child2Rep) 114dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond ); 115dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond } 116dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond 117dee0849a9704d532af0b550146cbafbaa6ee1d19Raymond} 118