exhaustivesearch.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.
 */

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

package  weka.attributeSelection;

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

/** 
 * Class for performing an exhaustive search. <p>
 *
 * Valid options are: <p>
 *
 * -P <start set> <br>
 * Specify a starting set of attributes. Eg 1,4,7-9. <p>
 *
 * -V <br>
 * Verbose output. Output new best subsets as the search progresses. <p>
 *
 * @author Mark Hall ([e-mail])
 * @version $Revision: 1.1.1.1 $
 */
public class ExhaustiveSearch extends ASSearch 
  implements StartSetHandler, OptionHandler {

  /** 
   * holds a starting set as an array of attributes.
   */
  private int[] m_starting;

  /** the start set as a Range */
  private Range m_startRange;

  /** the best feature set found during the search */
  private BitSet m_bestGroup;

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

 /** 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;

  /** if true, then ouput new best subsets as the search progresses */
  private boolean m_verbose;

  /** 
   * stop after finding the first subset equal to or better than the
   * supplied start set (set to true if start set is supplied).
   */
  private boolean m_stopAfterFirst;
  
  /** the number of subsets evaluated during the search */
  private int m_evaluations;

  /**
   * 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 "ExhaustiveSearch : \n\nPerforms an exhaustive search through "
      +"the space of attribute subsets starting from the empty set of "
      +"attrubutes. Reports the best subset found. If a start set is "
      +"supplied, the algorithm searches backward from the start point "
      +"and reports the smallest subset with as good or better evaluation "
      +"as the start point.\n";
  }

  /**
   * Constructor
   */
  public ExhaustiveSearch () {
    resetOptions();
  }

  /**
   * Returns an enumeration describing the available options.
   * @return an enumeration of all the available options.
   **/
  public Enumeration listOptions () {
    Vector newVector = new Vector(2);

    newVector.addElement(new Option("\tSpecify a starting set of attributes." 
				    + "\n\tEg. 1,3,5-7."
				    +"\n\tIf a start point is supplied,"
				    +"\n\tExhaustive search stops after"
				    +"\n\tfinding the smallest possible subset"
				    +"\n\twith merit as good as or better than"
				    +"\n\tthe start set."
				    ,"P",1
				    , "-P <start set>"));
    newVector.addElement(new Option("\tOutput subsets as the search progresses."
				    +"\n\t(default = false)."
				    , "V", 0
				    , "-V"));
    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>
   *
   * -V <br>
   * Verbose output. Output new best subsets as the search progresses. <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);
    }

    setVerbose(Utils.getFlag('V',options));
  }

  /**
   * 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. "" indicates no start set.
   * If a start point is supplied, Exhaustive search stops after finding
   * the smallest possible subset with merit as good as or better than the
   * start set. Otherwise, the search space is explored FULLY, and the
   * best subset returned.
   * @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 the tip text for this property
   * @return tip text for this property suitable for
   * displaying in the explorer/experimenter gui
   */
  public String verboseTipText() {
    return "Print progress information. Sends progress info to the terminal "
      +"as the search progresses.";
  }

  /**
   * set whether or not to output new best subsets as the search proceeds
   * @param v true if output is to be verbose
   */
  public void setVerbose(boolean v) {
    m_verbose = v;
  }

  /**
   * get whether or not output is verbose
   * @return true if output is set to verbose
   */
  public boolean getVerbose() {
    return m_verbose;
  }

  /**
   * Gets the current settings of RandomSearch.
   * @return an array of strings suitable for passing to setOptions()
   */
  public String[] getOptions () {
    String[] options = new String[3];
    int current = 0;

    if (!(getStartSet().equals(""))) {
      options[current++] = "-P";
      options[current++] = ""+startSetToString();
    }
	
    if (m_verbose) {
      options[current++] = "-V";
    }

    while (current < options.length) {
      options[current++] = "";
    }
    return  options;
  }

  /**
   * converts the array of starting attributes to a string. This is
   * used by getOptions to return the actual attributes specified
   * as the starting set. This is better than using m_startRanges.getRanges()
   * as the same start set can be specified in different ways from the
   * command line---eg 1,2,3 == 1-3. This is to ensure that stuff that
   * is stored in a database is comparable.
   * @return a comma seperated list of individual attribute numbers as a String
   */
  private String startSetToString() {
    StringBuffer FString = new StringBuffer();
    boolean didPrint;
    
    if (m_starting == null) {
      return getStartSet();
    }

    for (int i = 0; i < m_starting.length; i++) {
      didPrint = false;
      
      if ((m_hasClass == false) || 
	  (m_hasClass == true && i != m_classIndex)) {
	FString.append((m_starting[i] + 1));
	didPrint = true;
      }
      
      if (i == (m_starting.length - 1)) {
	FString.append("");
      }
      else {
	if (didPrint) {
	  FString.append(",");
	  }
      }
    }

    return FString.toString();
  }

  /**
   * prints a description of the search
   * @return a description of the search as a string
   */
  public String toString() {
    StringBuffer text = new StringBuffer();
    
    text.append("\tExhaustive Search.\n\tStart set: ");
    if (m_starting == null) {
      text.append("no attributes\n");
    }
    else {