complementnaivebayes.java

一个数据挖掘软件ALPHAMINERR的整个过程的JAVA版源代码

/*
 *    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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 *    ComplementNaiveBayes.java
 *    Copyright (C) 2003 Ashraf M. Kibriya
 *                  -- last updated 27/11/2003
 */

package weka.classifiers.bayes;

import weka.classifiers.Classifier;
import weka.core.FastVector;
import weka.core.Instance;
import weka.core.Instances;
import weka.core.Option;
import weka.core.OptionHandler;
import weka.core.Utils;
import weka.core.WeightedInstancesHandler;


/**
 * Class for building and using a Complement class Naive Bayes classifier.
 * For more information see,<p>
 *
 * ICML-2003 <i>Tackling the poor assumptions of Naive Bayes Text Classifiers</i>
 * P.S.: TF, IDF and length normalization transforms, as described in the
 * paper, can be performed through weka.filters.unsupervised.StringToWordVector.
 * <p>
 *
 * Valid options for the classifier are:<p>
 *
 * -N <br>
 * Normalizes word weights for each class.<p>
 *
 * -S val <br>
 * The smoothing value to use to avoid zero WordGivenClass probabilities
 * (default 1.0).
 *
 * @author Ashraf M. Kibriya ([e-mail])
 * @version $Revision$ 
 */

public class ComplementNaiveBayes extends Classifier
    implements OptionHandler, WeightedInstancesHandler {
    
    /**
	 * 
	 */
	private static final long serialVersionUID = 7246302925903086397L;

	/**
      Weight of words for each class. The weight is actually the
      log of the probability of a word (w) given a class (c) 
      (i.e. log(Pr[w|c])). The format of the matrix is: 
      wordWeights[class][wordAttribute]
    */
    private double[][] wordWeights;
    
    /** Holds the smoothing value to avoid word probabilities of zero.<br>
        P.S.: According to the paper this is the Alpha i parameter 
     */
    private double smoothingParameter = 1.0;
    
    /** True if the words weights are to be normalized */
    private boolean m_normalizeWordWeights = false;
    
    /** Holds the number of Class values present in the set of specified 
        instances */
    private int numClasses;
    
    /** The instances header that'll be used in toString */
    private Instances header;

    
    /**
     * Returns an enumeration describing the available options.
     *
     * @return an enumeration of all the available options.
     */
    public java.util.Enumeration listOptions() {
        FastVector newVector = new FastVector(2);
        newVector.addElement(
        new Option("\tNormalize the word weights for each class\n",
                   "N", 0,"-N"));
        newVector.addElement(
        new Option("\tSmoothing value to avoid zero WordGivenClass"+
                   " probabilities (default=1.0).\n",
                   "S", 1,"-S"));
        
        return newVector.elements();
    }
    
    /**
     * Gets the current settings of the classifier.
     *
     * @return an array of strings suitable for passing to setOptions
     */
    public String[] getOptions() {
        String options[] = new String[4];
        int current=0;
        
        if(getNormalizeWordWeights())
            options[current++] = "-N";
        
        options[current++] = "-S";
        options[current++] = Double.toString(smoothingParameter);
        
        while (current < options.length) {
            options[current++] = "";
        }
        
        return options;
    }        

    /**
     * Parses a given list of options. Valid options are:<p>
     *
     * -N <br>
     * Normalizes word weights for each class.<p>
     *
     * -S val <br>
     * The smoothing value to use to avoid zero WordGivenClass probabilities
     * (default 1.0).
     *
     * @param options the list of options as an array of strings
     * @exception Exception if an option is not supported
     */
    public void setOptions(String[] options) throws Exception {
        
        setNormalizeWordWeights(Utils.getFlag('N', options));
        
        String val = Utils.getOption('S', options);
        if(val.length()!=0)
          setSmoothingParameter(Double.parseDouble(val));
    }
    
    /**
     * Returns true if the word weights for each class are to be normalized
     */
    public boolean getNormalizeWordWeights() {
        return m_normalizeWordWeights;
    }
    
    /**
     * Sets whether if the word weights for each class should be normalized
     */
    public void setNormalizeWordWeights(boolean doNormalize) {
        m_normalizeWordWeights = doNormalize;
    }
    
    /**
     * Returns the tip text for this property
     * @return tip text for this property suitable for
     * displaying in the explorer/experimenter gui
     */
    public String normalizeWordWeightsTipText() {
        return "Normalizes the word weights for each class.";
    }
    
    /**
     * Gets the smoothing value to be used to avoid zero WordGivenClass
     * probabilities.
     */
    public double getSmoothingParameter() {
        return smoothingParameter;
    }

    /**
     * Sets the smoothing value used to avoid zero WordGivenClass probabilities
     */
    public void setSmoothingParameter(double val) {
        smoothingParameter = val;
    }
        
    /**
     * Returns the tip text for this property
     * @return tip text for this property suitable for
     * displaying in the explorer/experimenter gui
     */
    public String smoothingParameterTipText() {
        return "Sets the smoothing parameter to avoid zero WordGivenClass "+
               "probabilities (default=1.0).";
    }

    /**
     * Returns a string describing this classifier
     * @return a description of the classifier suitable for
     * displaying in the explorer/experimenter gui
     */
    public String globalInfo() {
        
        return  "Class for building and using a Complement class Naive Bayes "+
                "classifier. For more information see, \n"+
                "ICML-2003 \"Tackling the poor assumptions of Naive Bayes "+
                "Text Classifiers\" \n"+
                "P.S.: TF, IDF and length normalization transforms, as "+
                "described in the paper, can be performed through "+
                "weka.filters.unsupervised.StringToWordVector.";
    }