/*
* RapidMiner
*
* Copyright (C) 2001-2008 by Rapid-I and the contributors
*
* Complete list of developers available at our web site:
*
* http://rapid-i.com
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see http://www.gnu.org/licenses/.
*/
package com.rapidminer.operator.features.construction;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import com.rapidminer.example.Attribute;
import com.rapidminer.example.Tools;
import com.rapidminer.example.set.AttributeWeightedExampleSet;
import com.rapidminer.generator.FeatureGenerator;
import com.rapidminer.generator.GenerationException;
import com.rapidminer.operator.features.Individual;
import com.rapidminer.operator.features.IndividualOperator;
import com.rapidminer.tools.RandomGenerator;
/**
* The mutation operator for directed GGAs. This operator adds single attributes
* from the original set, creates new ones and deselect single attributes. The
* number of attributes remains until longer or shorter example sets have proven
* to perform better.
*
* @see DirectedGGA
* @author Ingo Mierswa
* @version $Id: DirectedGeneratingMutation.java,v 1.1 2006/04/14 07:47:17
* ingomierswa Exp $
*/
public class DirectedGeneratingMutation extends IndividualOperator {
private List generators;
private Attribute[] originalAttributes;
private double p;
private int maxGeneratedAttributes = 2;
private int maxAddedOriginalAttributes = 2;
private int maxDepth = -1;
private String[] unusableFunctions = new String[0];
private RandomGenerator random;
public DirectedGeneratingMutation(Attribute[] originalAttributes, double p, List generators, int maxGeneratedAttributes, int maxAddedOriginalAttributes, int maxDepth, String[] unusableFunctions, RandomGenerator random) {
this.originalAttributes = originalAttributes;
this.p = p / (maxGeneratedAttributes + maxAddedOriginalAttributes);
this.generators = generators;
this.maxGeneratedAttributes = maxGeneratedAttributes;
this.maxAddedOriginalAttributes = maxAddedOriginalAttributes;
this.maxDepth = maxDepth;
this.unusableFunctions = unusableFunctions;
this.random = random;
}
/**
* Performs one of the following three mutations:
* <ul>
* <li>add a newly generated attribute</li>
* <li>add an original attribute</li>
* <li>remove an attribute</li>
* </ul>
*/
public List<Individual> operate(Individual individual) throws Exception {
List<Individual> l = new LinkedList<Individual>();
AttributeWeightedExampleSet clone = (AttributeWeightedExampleSet) individual.getExampleSet().clone();
try {
addOriginalAttribute(clone);
addGeneratedAttribute(clone);
deselect(clone, maxGeneratedAttributes + maxAddedOriginalAttributes);
if (clone.getNumberOfUsedAttributes() > 0) {
l.add(new Individual(clone));
}
} catch (GenerationException e) {
individual.getExampleSet().getLog().logWarning("DirectedGGA: Exception occured during generation of attributes, using only original example set instead.");
}
l.add(individual);
return l;
}
private void addGeneratedAttribute(AttributeWeightedExampleSet exampleSet) throws GenerationException {
for (int i = 0; i < maxGeneratedAttributes; i++) {
if (random.nextDouble() < p) {
FeatureGenerator generator = FeatureGenerator.selectGenerator(exampleSet, generators, maxDepth, unusableFunctions, random);
if (generator != null) {
generator = generator.newInstance();
Attribute[] args = Tools.getWeightedCompatibleAttributes(exampleSet, generator, maxDepth, unusableFunctions, random);
generator.setArguments(args);
List<FeatureGenerator> generatorList = new LinkedList<FeatureGenerator>();
generatorList.add(generator);
List<Attribute> result = FeatureGenerator.generateAll(exampleSet.getExampleTable(), generatorList);
double weightSum = 0.0d;
for (int j = 0; j < args.length; j++)
weightSum += exampleSet.getWeight(args[j]);
weightSum /= args.length;
for (Attribute newAttribute : result)
exampleSet.getAttributes().addRegular(newAttribute);
Iterator<Attribute> a = result.iterator();
while (a.hasNext()) {
exampleSet.setWeight(a.next(), weightSum);
}
}
}
}
}
private void addOriginalAttribute(AttributeWeightedExampleSet exampleSet) {
for (int j = 0; j < maxAddedOriginalAttributes; j++) {
if (random.nextDouble() < p) {
Attribute originalAttribute = originalAttributes[random.nextInt(originalAttributes.length)];
double avgWeight = Tools.getAverageWeight(exampleSet);
if (!exampleSet.getAttributes().contains(originalAttribute)) {
exampleSet.getAttributes().addRegular(originalAttribute);
exampleSet.setWeight(originalAttribute, avgWeight);
}
}
}
}
private void deselect(AttributeWeightedExampleSet exampleSet, int numberNew) {
double[] probs = Tools.getInverseProbabilitiesFromWeights(exampleSet.getAttributes().createRegularAttributeArray(), exampleSet);
Iterator<Attribute> i = exampleSet.getAttributes().iterator();
int index = 0;
while (i.hasNext()) {
i.next();
if (random.nextDouble() < p * probs[index++] * numberNew) {
i.remove();
}
}
}
}