scalederror.java

一个很好的LIBSVM的JAVA源码。对于要研究和改进SVM算法的学者。可以参考。来自数据挖掘工具YALE工具包。

/*
 *  YALE - Yet Another Learning Environment
 *  Copyright (C) 2001-2004
 *      Simon Fischer, Ralf Klinkenberg, Ingo Mierswa, 
 *          Katharina Morik, Oliver Ritthoff
 *      Artificial Intelligence Unit
 *      Computer Science Department
 *      University of Dortmund
 *      44221 Dortmund,  Germany
 *  email: [e-mail]
 *  web:   http://yale.cs.uni-dortmund.de/
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License as 
 *  published by the Free Software Foundation; either version 2 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
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 *  USA.
 */
package edu.udo.cs.yale.operator.performance;

import edu.udo.cs.yale.example.Example;
import edu.udo.cs.yale.example.ExampleSet;
import edu.udo.cs.yale.example.ExampleReader;
import edu.udo.cs.yale.operator.OperatorException;
import edu.udo.cs.yale.tools.LogService;
import edu.udo.cs.yale.tools.math.*;

import java.text.*;

/** An absolute error which is scaled to the range of the values.
 *
 *  @author Ingo
 *  @version $Id: ScaledError.java,v 2.11 2004/08/27 11:57:43 ingomierswa Exp $
 */
public class ScaledError extends SimpleCriterion {

    /** Value range of the examples. */
    private double range = 1.0;

    public boolean formatPercent() { return true; }

    public String getName() { 
	return "scaled"; 
    }

    /** Calculates the range of the value. */
    public void startCounting(ExampleSet set) throws OperatorException { 
	super.startCounting(set);
	range = set.getLabel().getMaximum() - set.getLabel().getMinimum();
	if (range == 0) {
	    LogService.logMessage("Zero range in ScaledError! Danger of Division by zero. Range is set to 1 and ScaledError behave like an absolute error.", LogService.WARNING);
	    range = 1;
	}
    }

    public double countExample(double label, double predictedLabel) {
	return Math.abs((label - predictedLabel) / range);
    }

    protected void cloneAveragable(Averagable newPC) {
	super.cloneAveragable(newPC);
	this.range = ((ScaledError)newPC).range;
    }

    public String getDescription() {
	return "Average absolute deviation divided by the range of the true labels";
    }

}