mdlcriterion.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.tools.math.Averagable;
import edu.udo.cs.yale.example.Example;
import edu.udo.cs.yale.example.ExampleSet;
import edu.udo.cs.yale.example.AttributeWeightedExampleSet;
import edu.udo.cs.yale.operator.OperatorException;

/** Measures the length of an example set (i.e. the number of attributes). 
 * 
 *  @version $Id: MDLCriterion.java,v 2.4 2004/08/27 11:57:43 ingomierswa Exp $ 
 */
public class MDLCriterion extends MeasuredPerformance {

    /** The length of this example set. */
    private int length;

    public String getName() { return "mdl"; }
    
    public String getDescription() {
	return "Measures the length of an example set (i.e. the number of attributes).";
    }

    public void startCounting(ExampleSet eSet) throws OperatorException {
	super.startCounting(eSet);
	if (eSet instanceof AttributeWeightedExampleSet) {
	    this.length = ((AttributeWeightedExampleSet)eSet).getNumberOfUsedAttributes();
	} else {
	    this.length = eSet.getNumberOfAttributes();
	}
    }

    public void countExample(Example example) {}

    public double getFitness() {
 	return 1.0d / (double)length;
    }

    public double getValue() { return length; }

    public double getVariance() { return 0.0d; }

    public void cloneAveragable(Averagable other) {
 	this.length = ((MDLCriterion)other).length;
    }
}