/*
* 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.performance;
import com.rapidminer.example.Example;
import com.rapidminer.example.ExampleSet;
import com.rapidminer.example.set.AttributeWeightedExampleSet;
import com.rapidminer.operator.OperatorException;
import com.rapidminer.tools.math.Averagable;
/**
* Measures the length of an example set (i.e. the number of attributes).
*
* @author Ingo Mierswa
* @version $Id: MDLCriterion.java,v 1.4 2008/05/09 19:22:43 ingomierswa Exp $
*/
public class MDLCriterion extends MeasuredPerformance {
private static final long serialVersionUID = -5023462349084083154L;
/** The possible optimization directions. */
public static final String[] DIRECTIONS = { "minimization", "maximization" };
/**
* Indicates that the fitness should be higher for smaller numbers of
* features.
*/
public static final int MINIMIZATION = 0;
/**
* Indicates that the fitness should be higher for larger numbers of
* features.
*/
public static final int MAXIMIZATION = 1;
/** The length of this example set. */
private int length;
/** A counter for average building. */
private double counter = 1;
/**
* Indicates if the fitness should be higher or smaller depending on the
* number of features.
*/
private int direction = MINIMIZATION;
public MDLCriterion() {}
public MDLCriterion(int direction) {
this();
this.direction = direction;
}
public MDLCriterion(MDLCriterion mdl) {
super(mdl);
this.length = mdl.length;
this.counter = mdl.counter;
this.direction = mdl.direction;
}
public String getName() {
return "number_of_attributes";
}
public String getDescription() {
return "Measures the length of an example set (i.e. the number of attributes).";
}
public void startCounting(ExampleSet eSet, boolean useExampleWeights) throws OperatorException {
super.startCounting(eSet, useExampleWeights);
if (eSet instanceof AttributeWeightedExampleSet) {
this.length = ((AttributeWeightedExampleSet) eSet).getNumberOfUsedAttributes();
} else {
this.length = eSet.getAttributes().size();
}
}
public double getExampleCount() {
return counter;
}
public void countExample(Example example) {}
public double getFitness() {
switch (direction) {
case MINIMIZATION:
return (-1) * (double) length / counter;
case MAXIMIZATION:
return (double) length / (double) counter;
default:
return Double.NaN; // cannot happen
}
}
public double getMikroAverage() {
return (double) (length) / (double) counter;
}
public double getMikroVariance() {
return Double.NaN;
}
public void buildSingleAverage(Averagable averagable) {
MDLCriterion other = (MDLCriterion) averagable;
this.length += other.length;
this.counter++;
}
}