/*
* 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 java.util.Iterator;
import com.rapidminer.example.Attribute;
import com.rapidminer.example.Example;
import com.rapidminer.example.ExampleSet;
import com.rapidminer.operator.OperatorException;
import com.rapidminer.tools.math.Averagable;
/**
* The soft margin loss of a classifier, defined as
* the average over all 1 - y * f(x).
*
* @author Ingo Mierswa
* @version $Id: SoftMarginLoss.java,v 1.6 2008/05/09 19:22:43 ingomierswa Exp $
*/
public class SoftMarginLoss extends MeasuredPerformance {
private static final long serialVersionUID = -2987795640706342168L;
/** The value of the margin. */
private double margin = Double.NaN;
/** A counter for average building. */
private double counter = 1;
/** Clone constructor. */
public SoftMarginLoss() {}
public SoftMarginLoss(SoftMarginLoss m) {
super(m);
this.margin = m.margin;
this.counter = m.counter;
}
/** Calculates the margin. */
public void startCounting(ExampleSet exampleSet, boolean useExampleWeights) throws OperatorException {
super.startCounting(exampleSet, useExampleWeights);
// compute margin
Iterator<Example> reader = exampleSet.iterator();
this.margin = 0.0d;
this.counter = 0.0d;
Attribute labelAttr = exampleSet.getAttributes().getLabel();
Attribute weightAttribute = null;
if (useExampleWeights)
weightAttribute = exampleSet.getAttributes().getWeight();
while (reader.hasNext()) {
Example example = reader.next();
String trueLabel = example.getNominalValue(labelAttr);
double confidence = example.getConfidence(trueLabel);
double currentMargin = Math.max(0, 1.0d - confidence);
double weight = 1.0d;
if (weightAttribute != null)
weight = example.getValue(weightAttribute);
this.margin += currentMargin * weight;
this.counter += weight;
}
}
/** Does nothing. Everything is done in {@link #startCounting(ExampleSet, boolean)}. */
public void countExample(Example example) {}
public double getExampleCount() {
return counter;
}
public double getMikroVariance() {
return Double.NaN;
}
public double getMikroAverage() {
return margin / counter;
}
/** Returns 0.
*/
public double getMaxFitness() {
return 0.0d;
}
/** Returns the fitness. */
public double getFitness() {
return -1 * getAverage();
}
public String getName() {
return "soft_margin_loss";
}
public String getDescription() {
return "The average soft margin loss of a classifier, defined as the average of all 1 - confidences for the correct label.";
}
public void buildSingleAverage(Averagable performance) {
SoftMarginLoss other = (SoftMarginLoss) performance;
this.counter += other.counter;
this.margin += other.margin;
}
/** Returns the super class implementation of toString(). */
public String toString() {
return super.toString();
}
}