/*
* 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.similarity.bregmandivergences;
import com.rapidminer.example.Attribute;
import com.rapidminer.example.Example;
import com.rapidminer.example.ExampleSet;
/**
* The "Logistic loss ".
*
* @author Regina Fritsch
* @version $Id: LogisticLoss.java,v 1.4 2008/09/12 10:30:44 tobiasmalbrecht Exp $
*/
public class LogisticLoss extends AbstractBregmanDivergence {
public LogisticLoss(ExampleSet es) throws InstantiationException {
super(es);
}
public double distance(Example x, double[] y) {
double result = 0;
double xValue = 0;
for (Attribute att : x.getAttributes()) {
xValue = x.getValue(att);
}
result = xValue * Math.log(xValue / y[0]) + (1 - xValue) * Math.log( (1 - xValue) / (1 - y[0]) );
return result;
}
public boolean isApplicable(Example x) {
if (x.getAttributes().size() != 1) {
return false;
}
for (Attribute att : x.getAttributes()) {
/* greater/equal - if y is 0 or 1 there will be a division by zero*/
if (x.getValue(att) <= 0 || x.getValue(att) >= 1 ) {
return false;
}
}
return true;
}
}