classifiertree.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.learner.decisiontree.y45.j48;

import weka.core.*;
import weka.classifiers.*;
import java.io.*;

/**
 * Class for handling a tree structure used for
 * classification.
 *
 * @author Eibe Frank ([e-mail])
 * @version $Revision: 1.3 $
 */
public class ClassifierTree implements Drawable, Serializable {

  /** The model selection method. */  
  protected ModelSelection m_toSelectModel;     

  /** Local model at node. */
  protected ClassifierSplitModel m_localModel;  

  /** References to sons. */
  protected ClassifierTree [] m_sons;           

  /** True if node is leaf. */
  protected boolean m_isLeaf;                   

  /** True if node is empty. */
  protected boolean m_isEmpty;                  

  /** The training instances. */
  protected Instances m_train;                  

  /** The pruning instances. */
  protected Distribution m_test;     

  /** The id for the node. */
  protected int m_id;

  /** 
   * For getting a unique ID when outputting the tree (hashcode isn't
   * guaranteed unique) 
   */
  private static long PRINTED_NODES = 0;

  /**
   * Gets the next unique node ID.
   *
   * @return the next unique node ID.
   */
  protected static long nextID() {

    return PRINTED_NODES ++;
  }

  /**
   * Resets the unique node ID counter (e.g.
   * between repeated separate print types)
   */
  protected static void resetID() {

    PRINTED_NODES = 0;
  }

  /**
   * Constructor. 
   */
  public ClassifierTree(ModelSelection toSelectLocModel) {
    
    m_toSelectModel = toSelectLocModel;
  }

  /**
   * Method for building a classifier tree.
   *
   * @exception Exception if something goes wrong
   */
  public void buildClassifier(Instances data) throws Exception {

    if (data.checkForStringAttributes()) {
      throw new UnsupportedAttributeTypeException("Cannot handle string attributes!");
    }
    data = new Instances(data);
    data.deleteWithMissingClass();
    buildTree(data, false);
  }

  /**
   * Builds the tree structure.
   *
   * @param data the data for which the tree structure is to be
   * generated.
   * @param keepData is training data to be kept?
   * @exception Exception if something goes wrong
   */
  public void buildTree(Instances data, boolean keepData) throws Exception {
    
    Instances [] localInstances;

    if (keepData) {
      m_train = data;
    }
    m_test = null;
    m_isLeaf = false;
    m_isEmpty = false;
    m_sons = null;
    m_localModel = m_toSelectModel.selectModel(data);
    if (m_localModel.numSubsets() > 1) {
      localInstances = m_localModel.split(data);
      data = null;
      m_sons = new ClassifierTree [m_localModel.numSubsets()];
      for (int i = 0; i < m_sons.length; i++) {
	m_sons[i] = getNewTree(localInstances[i]);
	localInstances[i] = null;
      }
    }else{
      m_isLeaf = true;
      if (Utils.eq(data.sumOfWeights(), 0))
	m_isEmpty = true;
      data = null;
    }
  }

  /**
   * Builds the tree structure with hold out set
   *
   * @param train the data for which the tree structure is to be
   * generated.
   * @param test the test data for potential pruning
   * @param keepData is training Data to be kept?
   * @exception Exception if something goes wrong
   */
  public void buildTree(Instances train, Instances test, boolean keepData)
       throws Exception {
    
    Instances [] localTrain, localTest;
    int i;
    
    if (keepData) {
      m_train = train;
    }
    m_isLeaf = false;
    m_isEmpty = false;
    m_sons = null;
    m_localModel = m_toSelectModel.selectModel(train, test);
    m_test = new Distribution(test, m_localModel);
    if (m_localModel.numSubsets() > 1) {
      localTrain = m_localModel.split(train);
      localTest = m_localModel.split(test);
      train = test = null;
      m_sons = new ClassifierTree [m_localModel.numSubsets()];
      for (i=0;i<m_sons.length;i++) {
	m_sons[i] = getNewTree(localTrain[i], localTest[i]);
	localTrain[i] = null;
	localTest[i] = null;
      }
    }else{
      m_isLeaf = true;
      if (Utils.eq(train.sumOfWeights(), 0))
	m_isEmpty = true;
      train = test = null;
    }
  }

  /** 
   * Classifies an instance.
   *
   * @exception Exception if something goes wrong
   */
  public double classifyInstance(Instance instance) 
    throws Exception {

    double maxProb = -1;
    double currentProb;
    int maxIndex = 0;
    int j;

    for (j = 0; j < instance.numClasses(); j++) {
      currentProb = getProbs(j, instance, 1);
      if (Utils.gr(currentProb,maxProb)) {
	maxIndex = j;
	maxProb = currentProb;
      }
    }

    return (double)maxIndex;
  }

  /**
   * Cleanup in order to save memory.
   */
  public final void cleanup(Instances justHeaderInfo) {

    m_train = justHeaderInfo;
    m_test = null;
    if (!m_isLeaf)
      for (int i = 0; i < m_sons.length; i++)
	m_sons[i].cleanup(justHeaderInfo);
  }

  /** 
   * Returns class probabilities for a weighted instance.
   *
   * @exception Exception if something goes wrong
   */
  public final double [] distributionForInstance(Instance instance,
						 boolean useLaplace) 
       throws Exception {

    double [] doubles = new double[instance.numClasses()];

    for (int i = 0; i < doubles.length; i++) {
      if (!useLaplace) {
	doubles[i] = getProbs(i, instance, 1);
      } else {
	doubles[i] = getProbsLaplace(i, instance, 1);
      }
    }

    return doubles;
  }

  /**
   * Assigns a uniqe id to every node in the tree.
   */
  public int assignIDs(int lastID) {

    int currLastID = lastID + 1;

    m_id = currLastID;
    if (m_sons != null) {
      for (int i = 0; i < m_sons.length; i++) {
	currLastID = m_sons[i].assignIDs(currLastID);
      }
    }
    return currLastID;
  }

  /**
   *  Returns the type of graph this classifier
   *  represents.
   *  @return Drawable.TREE
   */   
  public int graphType() {
      return Drawable.TREE;
  }

  /**
   * Returns graph describing the tree.
   *
   * @exception Exception if something goes wrong
   */
  public String graph() throws Exception {

    StringBuffer text = new StringBuffer();

    assignIDs(-1);
    text.append("digraph J48Tree {\n");
    if (m_isLeaf) {
      text.append("N" + m_id 
		  + " [label=\"" + 
		  m_localModel.dumpLabel(0,m_train) + "\" " + 
		  "shape=box style=filled ");
      if (m_train != null && m_train.numInstances() > 0) {
	text.append("data =\n" + m_train + "\n");
	text.append(",\n");

      }
      text.append("]\n");
    }else {
      text.append("N" + m_id 
		  + " [label=\"" + 
		  m_localModel.leftSide(m_train) + "\" ");
      if (m_train != null && m_train.numInstances() > 0) {
	text.append("data =\n" + m_train + "\n");
	text.append(",\n");
     }
      text.append("]\n");
      graphTree(text);
    }
    
    return text.toString() +"}\n";
  }

  /**
   * Returns tree in prefix order.
   *
   * @exception Exception if something goes wrong
   */
  public String prefix() throws Exception {
    
    StringBuffer text;

    text = new StringBuffer();
    if (m_isLeaf) {
      text.append("["+m_localModel.dumpLabel(0,m_train)+"]");
    }else {
      prefixTree(text);
    }
    
    return text.toString();
  }

  /**
   * Returns source code for the tree as an if-then statement. The 
   * class is assigned to variable "p", and assumes the tested