/******************************************************************************* * Copyright (c) 2014 Opt4J * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. *******************************************************************************/ package org.opt4j.operators.crossover; import java.util.Random; import java.util.SortedSet; import java.util.TreeSet; import org.opt4j.core.common.random.Rand; import org.opt4j.core.genotype.ListGenotype; import com.google.inject.Inject; /** * <p> * The {@link CrossoverListXPoint} performs a crossover on * {@link org.opt4j.core.Genotype} objects that are lists of values. * </p> * <p> * The crossover is performed on {@code x} points of the * {@link org.opt4j.core.Genotype}. * </p> * * @author lukasiewycz * */ public abstract class CrossoverListXPoint<G extends ListGenotype<?>> implements Crossover<G> { protected final int x; protected final Random random; /** * Constructs a {@link CrossoverListXPoint}. * * @param x * the number of crossover points * @param random * the random number generator */ @Inject public CrossoverListXPoint(int x, Rand random) { this.x = x; this.random = random; } /* * (non-Javadoc) * * @see * org.opt4j.operator.crossover.Crossover#crossover(org.opt4j.core.Genotype, * org.opt4j.core.Genotype) */ @Override @SuppressWarnings("unchecked") public Pair<G> crossover(G p1, G p2) { ListGenotype<Object> o1 = p1.newInstance(); ListGenotype<Object> o2 = p2.newInstance(); int size = p1.size(); if (x <= 0 || x > size - 1) { throw new IllegalArgumentException(this.getClass() + " : x is " + x + " for binary vector size " + size); } SortedSet<Integer> points = new TreeSet<>(); while (points.size() < x) { points.add(random.nextInt(size - 1) + 1); } int flip = 0; boolean select = random.nextBoolean(); for (int i = 0; i < size; i++) { if (i == flip) { select = !select; if (points.size() > 0) { flip = points.first(); points.remove(flip); } } if (select) { o1.add(p1.get(i)); o2.add(p2.get(i)); } else { o1.add(p2.get(i)); o2.add(p1.get(i)); } } Pair<G> offspring = new Pair<>((G) o1, (G) o2); return offspring; } }