/*
* 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.learner.igss.utility;
import com.rapidminer.operator.learner.igss.hypothesis.Hypothesis;
/** The instance-averaging utility function Coverage.
*
* @author Dirk Dach
* @version $Id: Coverage.java,v 1.3 2008/05/09 19:23:23 ingomierswa Exp $
*/
public class Coverage extends InstanceAveraging {
/** Constructs a new Coverage with the given default probability.*/
public Coverage (double[] priors,int large) {
super(priors,large);
}
/** Calculates the utility for the given number of examples,positive examples and hypothesis.*/
public double utility (double totalWeight, double totalPositiveWeight, Hypothesis hypo) {
return hypo.getPositiveWeight()/totalWeight;
}
/** Calculates the empirical variance. */
public double variance(double totalWeight, double totalPositiveWeight, Hypothesis hypo) {
double mean=this.utility(totalWeight,totalPositiveWeight,hypo);
double innerTerm=hypo.getPositiveWeight()*Math.pow(1.0d-mean,2.0d)+(totalWeight-hypo.getPositiveWeight())*Math.pow(0.0d-mean,2.0d);
return Math.sqrt(innerTerm)/totalWeight;
}
/** Returns an upper bound for the utility of refinements for the given hypothesis. */
public double getUpperBound(double totalWeight, double totalPositiveWeight, Hypothesis hypo, double delta) {
// Never needed.
return 1.0d;
}
}