/*
* 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;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import com.rapidminer.example.Attribute;
import com.rapidminer.example.Statistics;
import com.rapidminer.example.set.AttributeWeightedExampleSet;
/**
* This individual operator removes all attributes from the example set which
* has weight 0 or the same minimum and maximum values.
*
* @author Ingo Mierswa
* @version $Id: RemoveUselessFeatures.java,v 2.12 2006/03/27 13:21:58
* ingomierswa Exp $
*/
public class RemoveUselessAttributes extends IndividualOperator {
public List<Individual> operate(Individual individual) throws Exception {
AttributeWeightedExampleSet exampleSet = individual.getExampleSet();
AttributeWeightedExampleSet clone = (AttributeWeightedExampleSet) exampleSet.clone();
clone.recalculateAllAttributeStatistics();
Iterator<Attribute> i = clone.getAttributes().iterator();
while (i.hasNext()) {
Attribute attribute = i.next();
double weight = clone.getWeight(attribute);
if (weight == 0.0d) {
i.remove();
} else if (!attribute.isNominal()) {
double min = clone.getStatistics(attribute, Statistics.MINIMUM);
double max = clone.getStatistics(attribute, Statistics.MAXIMUM);
if (min == max) {
// remove constant attributes if they are 0 or 1
if ((min == 0.0d) || (max == 1.0d))
i.remove();
}
}
}
LinkedList<Individual> l = new LinkedList<Individual>();
if (clone.getNumberOfUsedAttributes() > 0) {
l.add(new Individual(clone));
} else {
exampleSet.getLog().logWarning("No attributes left after removing useless attributes! Using original example set.");
l.add(new Individual(exampleSet));
}
return l;
}
}