BackwardElimination.java

/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2011 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.selection;

import java.util.LinkedList;
import java.util.List;

import com.rapidminer.operator.features.Individual;
import com.rapidminer.operator.features.IndividualOperator;


/**
 * This PopulationOperator realizes backward elimination, i.e. creates a list of
 * clones of each individual and switches of one attribute in each of the
 * clones.
 * 
 * @author Simon Fischer, Ingo Mierswa
 *          Exp $
 */
public class BackwardElimination extends IndividualOperator {

	@Override
	public List<Individual> operate(Individual individual) {
		double[] weights = individual.getWeights();

		List<Individual> l = new LinkedList<Individual>();
		for (int i = 0; i < weights.length; i++) {
			if (weights[i] > 0) {
				double[] newWeights = new double[weights.length];
				System.arraycopy(weights, 0, newWeights, 0, weights.length);
				newWeights[i] = 0;
				Individual newIndividual = new Individual(newWeights);
				if (newIndividual.getNumberOfUsedAttributes() > 0)
					l.add(newIndividual);
			}
		}
		return l;
	}
}