lbr.java

wekaUT是 university texas austin 开发的基于weka的半指导学习(semi supervised learning)的分类器

/*
 *    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
 *    aint with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */


/*
 *    LBR.java
 *    The naive Bayesian classifier provides a simple and effective approach to 
 *    classifier learning, but its attribute independence assumption is often 
 *    violated in the real world. Lazy Bayesian Rules selectively relaxes the 
 *    independence assumption, achieving lower error rates over a range of 
 *    learning tasks.  LBR defers processing to classification time, making it 
 *    a highly efficient and accurate classification algorithm when small
 *    numbers of objects are to be classified.
 *
 *    For more information, see<p>
 *    Zijian Zheng & G. Webb, (2000). <i>Lazy Learning of Bayesian Rules.</i> Machine Learning, 41(1): 53-84. 
 *
 *    http://www.cm.deakin.edu.au/webb
 *
 *    Copyright (C) 2001 Deakin University
 *    School of Computing and Mathematics
 *    Deakin University
 *    Geelong, Vic, 3217, Australia
 *
 *    Email: [e-mail]
 *
 */

package weka.classifiers.lazy;

import weka.classifiers.DistributionClassifier;
import weka.classifiers.Classifier;
import weka.classifiers.Evaluation;
import java.io.*;
import java.util.*;
import weka.core.*;

/**
 * Class for building and using a Lazy Bayesian classifier.<BR>
 * The naive Bayesian classifier provides a simple and effective approach to 
 * classifier learning, but its attribute independence assumption is often violated 
 * in the real world. A number of approaches have sought to alleviate this problem. 
 * A Bayesian tree learning algorithm builds a decision tree, and generates a local 
 * naive Bayesian classifier at each leaf. The tests leading to a leaf can alleviate 
 * attribute inter璬ependencies for the local naive Bayesian classifier. However, 
 * Bayesian tree learning still suffers from the small disjunct problem of tree learning. 
 * While inferred Bayesian trees demonstrate low average prediction error rates, there is 
 * reason to believe that error rates will be higher for those leaves with few training examples. <BR>
 *
 * For more information, see<p>
 * Zijian Zheng & G. Webb, (2000). <i>Lazy Learning of Bayesian Rules.</i> Machine Learning, 41(1): 53-84.<BR>
 * @author Zhihai Wang (Email: [e-mail]) : July 2001 implemented the algorithm
 * @author Jason Wells (Email: [e-mail]) : November 2001 added instance referencing via indexes
 *
 */
public class LBR extends DistributionClassifier {

  /**
   * Class for handling instances and the associated attributes. <p>
   * Enables a set of indexes to a given dataset to be created and used
   * with an algorithm.  This reduces the memory overheads and time required 
   * when manipulating and referencing Instances and their Attributes.  
   */
  public class Indexes implements Serializable {
    
    /** the array instance indexes **/
    public boolean [] m_InstIndexes;
    
    /** the array attribute indexes **/
    public boolean [] m_AttIndexes;
    
    /** the number of instances indexed **/
    private int m_NumInstances;
    
    /** the number of attributes indexed **/
    private int m_NumAtts;
    
    /** the array of instance indexes that are set to a either true or false **/
    public int [] m_SequentialInstIndexes;
    
    /** an array of attribute indexes that are set to either true or false **/
   public int [] m_SequentialAttIndexes;
    
    /** flag to check if sequential array must be rebuilt due to changes to the instance index*/
    private boolean m_SequentialInstanceIndex_valid = false;
    
   /** flag to check if sequential array must be rebuilt due to changes to the attribute index */
    private boolean m_SequentialAttIndex_valid = false;
    
    /** the number of instances "in use"  or set to a the original value (true or false) **/
    public int m_NumInstsSet;
    
    /** the number of attributes "in use"  or set to a the original value (true or false) **/
    public int m_NumAttsSet;
    
    /** the number of sequential instances "in use"  or set to a the original value (true or false) **/
    public int m_NumSeqInstsSet;
    
    /** the number of sequential attributes "in use"  or set to a the original value (true or false) **/
    public int m_NumSeqAttsSet;
    
    /** the Class Index for the data set **/
   public int m_ClassIndex;
    
    /**
     * constructor
     * @param numInstances the number of instances in dataset
     * @param numAtts the number of attributes in dataset
     * @param value either true or false
     * @param classIndex.  Set to -1 if you want class attribute switched on or the value of the instances 
     * class index will be switched of and the class attibute will not be considered.
     */
    public Indexes(int numInstances, int numAtts, boolean value, int classIndex) {
      /* to create an empty DATASET with all attributes indexed use FALSE
       * to create a index of all instances and attributes use TRUE
       */
      // initialise counts
      m_NumInstsSet =  m_NumInstances = numInstances;
      m_NumAttsSet = m_NumAtts = numAtts;
      
      m_InstIndexes = new boolean [(int)numInstances];
      
      /* set all indexes to value */
      int i = 0;
      while(i < numInstances) {
	m_InstIndexes[i] = value;
	i++;
      }
      
      m_AttIndexes = new boolean [(int)numAtts];
      
      /* set all indexes to true */
      i = 0;
      while(i < numAtts) {
	m_AttIndexes[i] = true;
	i++;
      }
      // if the value is false the dataset has no instances therefore no instances are set
      if(value == false)
        m_NumInstsSet = 0;
      // no sequential array has been created
      m_SequentialInstanceIndex_valid = false;
      m_SequentialAttIndex_valid = false;
      
      // switch class attr to false as the class is not used in the dataset.  Set to -1 if you want the class attr included
      if(classIndex != -1)
        setAttIndex(classIndex, false);
      m_ClassIndex = classIndex;
    }
    
    /**
     * constructor
     * @param FromIndexes the object you want to copy
     */
    public Indexes(Indexes FromIndexes) {
      // set counts to the FromIndexes counts
      m_NumInstances = FromIndexes.getNumInstances();
      m_NumInstsSet = FromIndexes.m_NumInstsSet;
      m_NumAtts = FromIndexes.m_NumAtts;
      m_NumAttsSet = FromIndexes.m_NumAttsSet;
      m_InstIndexes = new boolean [m_NumInstances];
      
      System.arraycopy(FromIndexes.m_InstIndexes, 0, m_InstIndexes, 0, m_NumInstances);
      
      m_AttIndexes = new boolean [(int)m_NumAtts];
      
      System.arraycopy(FromIndexes.m_AttIndexes, 0, m_AttIndexes, 0, m_NumAtts);
      m_ClassIndex = FromIndexes.m_ClassIndex;
      m_SequentialInstanceIndex_valid = false;
      m_SequentialAttIndex_valid = false;
    }
    
    /**
     * 
     * Changes the boolean value at the specified index in the InstIndexes array
     *
     * @param index the index of the instance
     * @param value the value to set at the specified index
     *
     */
    public void setInstanceIndex(int index, boolean value) {
      if(index < 0 || index >= m_NumInstances)
	throw new IllegalArgumentException("Invalid Instance Index value");
      // checks that the index isn't alreading set to value
      if(m_InstIndexes[(int)index] != value) {
	
	// set the value
	m_InstIndexes[(int)index] = value;
	
	// a change has been made, so sequential array is invalid
	m_SequentialInstanceIndex_valid = false;
	
	// change the number of values "in use" to appropriate value
	if(value == false)
	  m_NumInstsSet--;
	else
	  m_NumInstsSet++;
      }
   }
    
    /**
     * 
     * Changes the boolean value at the specified index in the InstIndexes array
     *
     * @param index the index of the instance
     * @param value the value to set at the specified index
     *
     */
    public void setAtts(int [] Attributes, boolean value) {
      for(int i = 0; i < m_NumAtts; i++) {
        m_AttIndexes[i] = !value;
      }
      for (int i = 0; i < Attributes.length; i++)  {
        m_AttIndexes[Attributes[i]] = value;
      }
      m_NumAttsSet = Attributes.length;
      m_SequentialAttIndex_valid = false;
    }
    
    /**
     * 
     * Changes the boolean value at the specified index in the InstIndexes array
     *
     * @param index the index of the instance
     * @param value the value to set at the specified index
     *
     */
    public void setInsts(int [] Instances, boolean value) {
      resetInstanceIndex(!value);
      for (int i = 0; i < Instances.length; i++)  {
        m_InstIndexes[Instances[i]] = value;
      }
      m_NumInstsSet = Instances.length;
      m_SequentialInstanceIndex_valid = false;
    }
    
    
    /**
     * 
     * Changes the boolean value at the specified index in the AttIndexes array
     *
     * @param index the index of the instance
     * @param value the value to set at the specified index
     *
     */
    public void setAttIndex(int index, boolean value) {
      if(index < 0 || index >= m_NumAtts)
	throw new IllegalArgumentException("Invalid Attribute Index value");
      // checks that the index isn't alreading set to value
      if(m_AttIndexes[(int)index] != value) {
	
	// set the value
	m_AttIndexes[(int)index] = value;
	
	// a change has been made, so sparse array is invalid
	m_SequentialAttIndex_valid = false;  
	
	 // change the number of values "in use" to appropriate value
	if(value == false)
	  m_NumAttsSet--;
	else
	  m_NumAttsSet++;
      }
    }
    
    /**
     * 
     * Returns the boolean value at the specified index in the Instance Index array
     *
     * @param index the index of the instance
     * 
     */
    public boolean getInstanceIndex(int index) {
      
      if(index < 0 || index >= m_NumInstances)
	throw new IllegalArgumentException("Invalid index value");
      
      return m_InstIndexes[(int)index]; 
    }
    
    /**
     * 
     * Returns the boolean value at the specified index in the Sequential Instance Indexes array
     *
     * @param index the index of the instance
     * 
     */
    public int getSequentialInstanceIndex(int index) {
      
      if(index < 0 || index >= m_NumInstances)
	throw new IllegalArgumentException("Invalid index value");
      
      return m_SequentialInstIndexes[(int)index]; 
    }
    
    /**
     * 
     * Resets the boolean value in the Instance Indexes array to a specified value
     *
     * @param value the value to set all indexes
     * 
    */
    public void resetInstanceIndex(boolean value) {
      m_NumInstsSet = m_NumInstances;
      for(int i = 0; i < m_NumInstances; i++) {
	m_InstIndexes[i] = value;
      }
      if(value == false)
	m_NumInstsSet =  0;
      m_SequentialInstanceIndex_valid = false;
    }
    
   /**
    * 
    * Resets the boolean values in Attribute and Instance array to reflect an empty dataset withthe same attributes set as in the incoming Indexes Object
    *
    * @param FromIndexes the Indexes to be copied
    * 
    */
    public void resetDatasetBasedOn(Indexes FromIndexes) {
      resetInstanceIndex(false);
      resetAttIndexTo(FromIndexes);
    }
   
    /**
     * 
     * Resets the boolean value in AttIndexes array
     *
     * @param value the value to set the attributes to
     * 
     */
    public void resetAttIndex(boolean value) {
      m_NumAttsSet =  m_NumAtts;
      for(int i = 0; i < m_NumAtts; i++) {
	m_AttIndexes[i] = value;
      }
      if(m_ClassIndex != -1)
	setAttIndex(m_ClassIndex, false);
      if(value == false)
	m_NumAttsSet =  0;
     m_SequentialAttIndex_valid = false;
    }
    
    /**
     * 
     * Resets the boolean value in AttIndexes array based on another set of Indexes
     *
     * @param FromIndexes the Indexes to be copied
     * 
    */
    public void resetAttIndexTo(Indexes FromIndexes) {
      System.arraycopy(FromIndexes.m_AttIndexes, 0, m_AttIndexes, 0, m_NumAtts);
      m_NumAttsSet =  FromIndexes.getNumAttributesSet();
      m_ClassIndex = FromIndexes.m_ClassIndex;
      m_SequentialAttIndex_valid = false;
    }
    
    /**
     * 
     * Returns the boolean value at the specified index in the Attribute Indexes array