averagable.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.tools.math;

import edu.udo.cs.yale.example.ExampleSet;
import edu.udo.cs.yale.example.Example;
import edu.udo.cs.yale.tools.LogService;
import edu.udo.cs.yale.operator.ResultObjectAdapter;

import java.util.*;
import java.text.*;

/** Superclass for all objects which can be averaged. Averagable objects can be stored in a average vector. 
 *
 *  @version $Id: Averagable.java,v 1.6 2004/09/12 11:09:53 ingomierswa Exp $
 */
public abstract class Averagable extends ResultObjectAdapter implements Cloneable, Comparable {

    /** Used for formatting values in the {@link #toString()} method. */
    private static final NumberFormat NUMBER_FORMAT = NumberFormat.getInstance();

    /** Used for formatting values in the {@link #formatValue(double)} method. */
    private static final NumberFormat PERCENT_FORMAT = NumberFormat.getPercentInstance();
    
    static {
	PERCENT_FORMAT.setMaximumFractionDigits(2);
	PERCENT_FORMAT.setMinimumFractionDigits(2);
	NUMBER_FORMAT.setMaximumFractionDigits(3);
	NUMBER_FORMAT.setMinimumFractionDigits(3);
    }


    /** The averages are summed up each time buildAverage is called. */
    private double meanSum = Double.NaN;

    /** The squared averages are summed up each time buildAverage is called. */
    private double meanSquaredSum = Double.NaN;

    /** Counts the number of times, build average was executed. */
    private int averageCount = 0;



    /** Returns the name of this averagable. */
    public abstract String getName();

    /** Returns the value of the averagable (the average itself). */
    public abstract double getValue();

    /** Returns the variance of the averagable. */
    public abstract double getVariance();

    /** Must be implemented by subclasses such that it copies
     *  all values of <code>other</code> to <code>this</code>.
     *  When this method is called, it is guaranteed, that <code>other</code> is a subclass
     *  of the class of the object it is called on. */
    protected abstract void cloneAveragable(Averagable other);


    // ================================================================================


    /** This method builds the average of two averagables of the same type.
     *  First this method checks if the classes of <code>this</code> and 
     *  <code>performance</code> are the same and if the
     *  {@link #getName()} methods return the same String. Otherwise
     *  a RuntimeException is thrown.
     *  <br>
     *  The value of <code>averagable.</code>{@link #getValue()} is added to
     *  {@link #meanSum}, its square is added to
     *  {@link #meanSquaredSum} and 
     *  {@link #averageCount} is increased by one. These
     *   values are used in the {@link #getMakroAverage()} and 
     *  {@link #getMakroVariance()} methods.
     *  <br>
     *  Subclasses should implement this method to build the weighted average of
     *  <code>this</code> measured performance and <code>performance</code>. They
     *  must be weighted by the number of examples used for calculating the
     *  criteria. Subclasses <code>must</code> call <code>super.buildAverage</code>
     *  before they do anything that changes the return value of
     *  <code>performance.</code>{@link #getValue()}! */
    public void buildAverage(Averagable averagable) {
	if (!averagable.getClass().equals(this.getClass()))
	    throw new RuntimeException("Cannot build average of different averagable types ("+
				       this.getClass().getName()+"/"+averagable.getClass().getName()+").");
	if (!averagable.getName().equals(this.getName()))
	    throw new RuntimeException("Cannot build average of different averagable types ("+
				       this.getName()+"/"+averagable.getName()+").");
	
	if (averageCount == 0) { // count yourself
	    double value   = this.getValue();
	    meanSum        = value;
	    meanSquaredSum = value*value;
	    averageCount  = 1;
	}
	double value   = averagable.getValue();
	meanSum        += value;
	meanSquaredSum += value*value;
	averageCount++;
    }

    /** Returns the standard deviation of the performance criterion. */
    public double getStandardDeviation() {
	double variance = getVariance();
	if (Double.isNaN(variance)) return Double.NaN;
	else return Math.sqrt(variance);
    }

    /** Returns the average value of all performance criteria average by using the
     *  {@link #buildAverage(Averagable)} method. */
    public double getMakroAverage() {
	return meanSum / averageCount;
    }

    /** Returns the variance of all performance criteria average by using the
     *  {@link #buildAverage(Averagable)} method. */
    public double getMakroVariance() {
	double mean = getMakroAverage();
	return meanSquaredSum / averageCount - mean * mean;
    }

    /** Returns the standard deviation of all performance criteria average by using the
     *  {@link #buildAverage(Averagable)} method. */
    public double getMakroStandardDeviation() {
	return Math.sqrt(getMakroVariance());
    }

    /** Returns a (deep) clone of this averagable. */
    public Object clone() {
	try {
	    Class clazz = this.getClass();
	    Averagable clone = (Averagable)clazz.newInstance();
	    clone.meanSum        = this.meanSum;
	    clone.meanSquaredSum = this.meanSquaredSum;
	    clone.averageCount   = this.averageCount;
	    clone.cloneAveragable(this);
	    return clone;
	} catch (Exception e) {
	    LogService.logException("In Averagable.clone():", e);
	    return null;
	}
    }


    // ================================================================================

    /** Indicates wether or not percentage format should be used in the
     *  {@link #toString} method. The default implementation returns false. */
    public boolean formatPercent() { return false; }

    /** Formats the value for the {@link #toString()} method. */
    protected String formatValue(double value) {
	if (Double.isNaN(value)) return "unknown";
	else {
	    if (formatPercent()) {
		return PERCENT_FORMAT.format(value);
	    } else {
		return NUMBER_FORMAT.format(value);
	    }
	}
    }

    /** Formats the standard deviation for the {@link #toString()} method. */
    protected String formatDeviation(double dev) {
	if (formatPercent()) {
	    return PERCENT_FORMAT.format(dev);
	} else {
	    return NUMBER_FORMAT.format(dev);
	}
    }

    public String toString() {
	String str = getName()+": "+formatValue(getValue());
	double sd = getStandardDeviation();
	if (!Double.isNaN(sd)) str += " +/- "+formatDeviation(sd);

	if (averageCount > 0) {
	    str += " (makro avg: "+formatValue(getMakroAverage());
	    sd  = getMakroStandardDeviation();	
	    if (!Double.isNaN(sd)) str += " +/- "+formatDeviation(sd);
	    str += ")";
	}
	return str;
    }
    
    /** Returns a HTML result string. Default implementation returns toString(). */
    public String toHTML() {
	return toString();
    }
}