001 package org.jaga.reproduction.booleanFormulas;
002
003 import org.jaga.reproduction.booleanFormulas.nodes.*;
004 import org.jaga.individualRepresentation.booleanFormulas.*;
005 import org.jaga.reproduction.Mutation;
006 import org.jaga.definitions.*;
007
008 /**
009 * TODO: Complete these comments.
010 *
011 * <p><u>Project:</u> JAGA - Java API for Genetic Algorithms.</p>
012 *
013 * <p><u>Company:</u> University College London and JAGA.Org
014 * (<a href="http://www.jaga.org" target="_blank">http://www.jaga.org</a>).
015 * </p>
016 *
017 * <p><u>Copyright:</u> (c) 2004 by G. Paperin.<br/>
018 * This program is free software; you can redistribute it and/or modify
019 * it under the terms of the GNU General Public License as published by
020 * the Free Software Foundation, ONLY if you include a note of the original
021 * author(s) in any redistributed/modified copy.<br/>
022 * This program is distributed in the hope that it will be useful,
023 * but WITHOUT ANY WARRANTY; without even the implied warranty of
024 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
025 * GNU General Public License for more details.<br/>
026 * You should have received a copy of the GNU General Public License
027 * along with this program; if not, write to the Free Software
028 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
029 * or see http://www.gnu.org/licenses/gpl.html</p>
030 *
031 * @author Greg Paperin (greg@jaga.org)
032 *
033 * @version JAGA public release 1.0 beta
034 */
035
036 public class FunctionTreeMutation extends Mutation {
037
038 private static final Class applicableClass = BooleanFormulaTree.class;
039
040 public FunctionTreeMutation() {
041 super();
042 }
043
044 public FunctionTreeMutation(double mutProb) {
045 super(mutProb);
046 }
047
048 public Class getApplicableClass() {
049 return applicableClass;
050 }
051
052 public Individual[] reproduce(Individual[] parents, GAParameterSet params) {
053
054 Individual [] kids = new Individual[parents.length];
055 for (int i = 0; i < kids.length; i++) {
056 if (!getApplicableClass().isInstance(parents[i]))
057 throw new ClassCastException("Incompatible parent class: must be "
058 + getApplicableClass().getName()
059 + ", but is " + parents.getClass().getName());
060 kids[i] = mutate((BooleanFormulaTree) parents[i], params);
061 }
062 return kids;
063 }
064
065 private BooleanFormulaTree mutate(BooleanFormulaTree parent, GAParameterSet params) {
066
067 BooleanFormulaTree kid = createSpecificIndividual(parent, params);
068
069 if (params.getRandomGenerator().nextDouble() < getMutationProbability()) {
070 final BooleanFormulaTreeFactory fact = fetchFactory(params);
071 final Long handle = kid.selectRandomNode(params);
072 int depth = kid.getNodeDepth(handle);
073 BooleanFormulaTreeNode replacement = fact.createRandomNode(depth, params);
074 kid.replaceNode(handle, replacement);
075 kid.setFitness(null);
076 }
077
078 return kid;
079 }
080
081 private BooleanFormulaTree createSpecificIndividual(Object init, GAParameterSet params) {
082 final BooleanFormulaTreeFactory fact = fetchFactory(params);
083 final Individual form = (BooleanFormulaTree) fact.createSpecificIndividual(init, params);
084 return (BooleanFormulaTree) form;
085 }
086
087 private BooleanFormulaTreeFactory fetchFactory(GAParameterSet params) {
088 return (BooleanFormulaTreeFactory) params.getIndividualsFactory();
089 }
090
091 }