ranker.java

这是关于数据挖掘的一些算法

/*
 *    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.
 */

/*
 *    Ranker.java
 *    Copyright (C) 1999 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.attributeSelection;

import weka.core.Instances;
import weka.core.Option;
import weka.core.OptionHandler;
import weka.core.Range;
import weka.core.Utils;

import java.util.Enumeration;
import java.util.Vector;

/** 
 <!-- globalinfo-start -->
 * Ranker : <br/>
 * <br/>
 * Ranks attributes by their individual evaluations. Use in conjunction with attribute evaluators (ReliefF, GainRatio, Entropy etc).<br/>
 * <p/>
 <!-- globalinfo-end -->
 *
 <!-- options-start -->
 * Valid options are: <p/>
 * 
 * <pre> -P &lt;start set&gt;
 *  Specify a starting set of attributes.
 *  Eg. 1,3,5-7.
 *  Any starting attributes specified are
 *  ignored during the ranking.</pre>
 * 
 * <pre> -T &lt;threshold&gt;
 *  Specify a theshold by which attributes
 *  may be discarded from the ranking.</pre>
 * 
 * <pre> -N &lt;num to select&gt;
 *  Specify number of attributes to select</pre>
 * 
 <!-- options-end -->
 *
 * @author Mark Hall ([e-mail])
 * @version $Revision: 1.25 $
 */
public class Ranker 
  extends ASSearch 
  implements RankedOutputSearch, StartSetHandler, OptionHandler {
  
  /** for serialization */
  static final long serialVersionUID = -9086714848510751934L;

  /** Holds the starting set as an array of attributes */
  private int[] m_starting;

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

  /** Holds the ordered list of attributes */
  private int[] m_attributeList;

  /** Holds the list of attribute merit scores */
  private double[] m_attributeMerit;

  /** Data has class attribute---if unsupervised evaluator then no class */
  private boolean m_hasClass;

  /** Class index of the data if supervised evaluator */
  private int m_classIndex;

  /** The number of attribtes */
  private int m_numAttribs;

  /** 
   * 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;

  /** Used to compute the number to select */
  private int m_calculatedNumToSelect = -1;

  /**
   * 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 "Ranker : \n\nRanks attributes by their individual evaluations. "
      +"Use in conjunction with attribute evaluators (ReliefF, GainRatio, "
      +"Entropy etc).\n";
  }

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

  /**
   * 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. -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 to select. This might be computed
   * from a threshold, or if < 0 is set as the number to select then
   * it is set to the number of attributes in the (transformed) data.
   * @return the calculated number of attributes to select
   */
  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 thresholdTipText() {
    return "Set threshold by which attributes can be discarded. Default value "
      + "results in no attributes being discarded. Use either this option or "
      +"numToSelect to reduce the attribute set.";
  }

  /**
   * 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 generateRankingTipText() {
    return "A constant option. Ranker is only capable of generating "
      +" attribute rankings.";
  }

  /**
   * This is a dummy set method---Ranker is ONLY capable of producing
   * a ranked list of attributes for attribute evaluators.
   * @param doRank this parameter is N/A and is ignored
   */
  public void setGenerateRanking(boolean doRank) {
    
  }

  /**
   * This is a dummy method. Ranker can ONLY be used with attribute
   * evaluators and as such can only produce a ranked list of attributes
   * @return true all the time.
   */
  public boolean getGenerateRanking() {
    return true;
  }

  /**
   * 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 "Specify a set of attributes to ignore. "
      +" When generating the ranking, Ranker will not evaluate the attributes "
      +" in this list. "
      +"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.
   * @throws 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.\n"
                             +"\tAny starting attributes specified are\n"
                             +"\tignored during the ranking."
                             ,"P",1
                             , "-P <start set>"));
    newVector
      .addElement(new Option("\tSpecify a theshold by which attributes\n" 
                             + "\tmay be discarded from the ranking.","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. <p/>
   *
   <!-- options-start -->
   * Valid options are: <p/>
   * 
   * <pre> -P &lt;start set&gt;
   *  Specify a starting set of attributes.
   *  Eg. 1,3,5-7.
   *  Any starting attributes specified are
   *  ignored during the ranking.</pre>
   * 
   * <pre> -T &lt;threshold&gt;
   *  Specify a theshold by which attributes
   *  may be discarded from the ranking.</pre>
   * 
   * <pre> -N &lt;num to select&gt;
   *  Specify number of attributes to select</pre>
   * 
   <!-- options-end -->
   *
   * @param options the list of options as an array of strings
   * @throws 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) {