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

/*
 *    ForwardSelection.java
 *    Copyright (C) 1999 Mark Hall
 *
 */

package  weka.attributeSelection;

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

/** 
 * Class for performing a forward selection hill climbing search. <p>
 *
 * Valid options are: <p>
 *
 * -P <start set> <br>
 * Specify a starting set of attributes. Eg 1,4,7-9. <p>
 *
 * -R <br>
 * Produce a ranked list of attributes. <p>
 * 
 * -T <threshold> <br>
 * Specify a threshold by which the AttributeSelection module can. <br>
 * discard attributes. Use in conjunction with -R <p>
 *
 * @author Mark Hall ([e-mail])
 * @version $Revision: 1.1.1.1 $
 */
public class ForwardSelection extends ASSearch 
  implements RankedOutputSearch, StartSetHandler, OptionHandler {

 /** does the data have a class */
  private boolean m_hasClass;
 
  /** holds the class index */
  private int m_classIndex;
 
  /** number of attributes in the data */
  private int m_numAttribs;

  /** true if the user has requested a ranked list of attributes */
  private boolean m_rankingRequested;

  /** 
   * go from one side of the search space to the other in order to generate
   * a ranking
   */
  private boolean m_doRank;

  /** used to indicate whether or not ranking has been performed */
  private boolean m_doneRanking;

  /**
   * A threshold by which to discard attributes---used by the
   * AttributeSelection module
   */
  private double m_threshold;

  /** The number of attributes to select. -1 indicates that all attributes
      are to be retained. Has precedence over m_threshold */
  private int m_numToSelect = -1;

  private int m_calculatedNumToSelect;

  /** the merit of the best subset found */
  private double m_bestMerit;

  /** a ranked list of attribute indexes */
  private double [][] m_rankedAtts;
  private int m_rankedSoFar;

  /** the best subset found */
  private BitSet m_best_group;
  private ASEvaluation m_ASEval;

  private Instances m_Instances;

  /** holds the start set for the search as a Range */
  private Range m_startRange;

  /** holds an array of starting attributes */
  private int [] m_starting;

  /**
   * Returns a string describing this search method
   * @return a description of the search suitable for
   * displaying in the explorer/experimenter gui
   */
  public String globalInfo() {
    return "ForwardSelection :\n\nPerforms a greedy forward search through "
      +"the space of attribute subsets. May start with no attributes or from "
      +"an arbitrary point in the space. Stops when the addition of any "
      +"remaining attributes results in a decrease in evaluation. "
      +"Can also produce a ranked list of "
      +"attributes by traversing the space from one side to the other and "
      +"recording the order that attributes are selected.\n";
  }

  public ForwardSelection () {
    m_threshold = -Double.MAX_VALUE;
    m_doneRanking = false;
    m_startRange = new Range();
    m_starting = null;
    resetOptions();
  }

  /**
   * Returns the tip text for this property
   * @return tip text for this property suitable for
   * displaying in the explorer/experimenter gui
   */
  public String thresholdTipText() {
    return "Set threshold by which attributes can be discarded. Default value "
      + "results in no attributes being discarded. Use in conjunction with "
      + "generateRanking";
  }

  /**
   * Set the threshold by which the AttributeSelection module can discard
   * attributes.
   * @param threshold the threshold.
   */
  public void setThreshold(double threshold) {
    m_threshold = threshold;
  }

  /**
   * Returns the threshold so that the AttributeSelection module can
   * discard attributes from the ranking.
   */
  public double getThreshold() {
    return m_threshold;
  }

  /**
   * Returns the tip text for this property
   * @return tip text for this property suitable for
   * displaying in the explorer/experimenter gui
   */
  public String numToSelectTipText() {
    return "Specify the number of attributes to retain. The default value "
      +"(-1) indicates that all attributes are to be retained. Use either "
      +"this option or a threshold to reduce the attribute set.";
  }

  /**
   * Specify the number of attributes to select from the ranked list
   * (if generating a ranking). -1
   * indicates that all attributes are to be retained.
   * @param n the number of attributes to retain
   */
  public void setNumToSelect(int n) {
    m_numToSelect = n;
  }

  /**
   * Gets the number of attributes to be retained.
   * @return the number of attributes to retain
   */
  public int getNumToSelect() {
    return m_numToSelect;
  }

  /**
   * Gets the calculated number of attributes to retain. This is the
   * actual number of attributes to retain. This is the same as
   * getNumToSelect if the user specifies a number which is not less
   * than zero. Otherwise it should be the number of attributes in the
   * (potentially transformed) data.
   */
  public int getCalculatedNumToSelect() {
    if (m_numToSelect >= 0) {
      m_calculatedNumToSelect = m_numToSelect;
    }
    return m_calculatedNumToSelect;
  }

  /**
   * Returns the tip text for this property
   * @return tip text for this property suitable for
   * displaying in the explorer/experimenter gui
   */
  public String generateRankingTipText() {
    return "Set to true if a ranked list is required.";
  }
  
  /**
   * Records whether the user has requested a ranked list of attributes.
   * @param doRank true if ranking is requested
   */
  public void setGenerateRanking(boolean doRank) {
    m_rankingRequested = doRank;
  }

  /**
   * Gets whether ranking has been requested. This is used by the
   * AttributeSelection module to determine if rankedAttributes()
   * should be called.
   * @return true if ranking has been requested.
   */
  public boolean getGenerateRanking() {
    return m_rankingRequested;
  }

  /**
   * Returns the tip text for this property
   * @return tip text for this property suitable for
   * displaying in the explorer/experimenter gui
   */
  public String startSetTipText() {
    return "Set the start point for the search. This is specified as a comma "
      +"seperated list off attribute indexes starting at 1. It can include "
      +"ranges. Eg. 1,2,5-9,17.";
  }

  /**
   * Sets a starting set of attributes for the search. It is the
   * search method's responsibility to report this start set (if any)
   * in its toString() method.
   * @param startSet a string containing a list of attributes (and or ranges),
   * eg. 1,2,6,10-15.
   * @exception Exception if start set can't be set.
   */
  public void setStartSet (String startSet) throws Exception {
    m_startRange.setRanges(startSet);
  }

  /**
   * Returns a list of attributes (and or attribute ranges) as a String
   * @return a list of attributes (and or attribute ranges)
   */
  public String getStartSet () {
    return m_startRange.getRanges();
  }

  /**
   * Returns an enumeration describing the available options.
   * @return an enumeration of all the available options.
   **/
  public Enumeration listOptions () {
    Vector newVector = new Vector(3);

    newVector
      .addElement(new Option("\tSpecify a starting set of attributes." 
			     + "\n\tEg. 1,3,5-7."
			     ,"P",1
			     , "-P <start set>"));

    newVector.addElement(new Option("\tProduce a ranked list of attributes."
				    ,"R",0,"-R"));
    newVector
      .addElement(new Option("\tSpecify a theshold by which attributes" 
			     + "\n\tmay be discarded from the ranking."
			     +"\n\tUse in conjuction with -R","T",1
			     , "-T <threshold>"));

    newVector
      .addElement(new Option("\tSpecify number of attributes to select" 
			     ,"N",1
			     , "-N <num to select>"));

    return newVector.elements();

  }
  
  /**
   * Parses a given list of options.
   *
   * Valid options are: <p>
   * 
   * -P <start set> <br>
   * Specify a starting set of attributes. Eg 1,4,7-9. <p>
   *
   * -R <br>
   * Produce a ranked list of attributes. <p>
   * 
   * -T <threshold> <br>
   * Specify a threshold by which the AttributeSelection module can <br>
   * discard attributes. Use in conjunction with -R <p>
   *
   * -N <number to retain> <br>
   * Specify the number of attributes to retain. Overides any threshold. <br>
   * <p>
   *
   * @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 {
    String optionString;
    resetOptions();

    optionString = Utils.getOption('P', options);
    if (optionString.length() != 0) {
      setStartSet(optionString);
    }