nominaltobinary.java

一个数据挖掘软件ALPHAMINERR的整个过程的JAVA版源代码

/*
 *    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.
 */

/*
 *    NominalToBinary.java
 *    Copyright (C) 1999 Eibe Frank
 *
 */


package weka.filters.supervised.attribute;

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

import weka.core.Attribute;
import weka.core.FastVector;
import weka.core.Instance;
import weka.core.Instances;
import weka.core.Option;
import weka.core.OptionHandler;
import weka.core.SparseInstance;
import weka.core.UnassignedClassException;
import weka.core.Utils;
import weka.filters.Filter;
import weka.filters.SupervisedFilter;

/** 
 * Converts all nominal attributes into binary numeric attributes. An
 * attribute with k values is transformed into k binary attributes if
 * the class is nominal (using the one-attribute-per-value approach).
 * Binary attributes are left binary.
 *
 * If the class is numeric, k - 1 new binary attributes are generated
 * (in the manner described in "Classification and Regression
 * Trees").<p>
 *
 * Valid filter-specific options are: <p>
 *
 * -N <br>
 * If binary attributes are to be coded as nominal ones.<p>
 *
 * @author Eibe Frank ([e-mail]) 
 * @version $Revision$ 
 */
public class NominalToBinary extends Filter implements SupervisedFilter,
						       OptionHandler {

  /** The sorted indices of the attribute values. */
  private int[][] m_Indices = null;

  /** Are the new attributes going to be nominal or numeric ones? */
  private boolean m_Numeric = true;

  /**
   * Returns a string describing this filter
   *
   * @return a description of the filter suitable for
   * displaying in the explorer/experimenter gui
   */
  public String globalInfo() {

    return "Converts all nominal attributes into binary numeric attributes. An "
      + "attribute with k values is transformed into k binary attributes if "
      + "the class is nominal (using the one-attribute-per-value approach). "
      + "Binary attributes are left binary."
      + "If the class is numeric, k - 1 new binary attributes are generated "
      + "in the manner described in \"Classification and Regression "
      + "Trees\" by Breiman et al. (i.e. taking the average class value associated "
      + "with each attribute value into account)";
  }

  /**
   * Sets the format of the input instances.
   *
   * @param instanceInfo an Instances object containing the input 
   * instance structure (any instances contained in the object are 
   * ignored - only the structure is required).
   * @return true if the outputFormat may be collected immediately
   * @exception Exception if the input format can't be set 
   * successfully
   */
  public boolean setInputFormat(Instances instanceInfo) 
       throws Exception {

    super.setInputFormat(instanceInfo);
    if (instanceInfo.classIndex() < 0) {
      throw new UnassignedClassException("No class has been assigned to the instances");
    }
    setOutputFormat();
    m_Indices = null;
    if (instanceInfo.classAttribute().isNominal()) {
      return true;
    } else {
      return false;
    }
  }

  /**
   * Input an instance for filtering. Filter requires all
   * training instances be read before producing output.
   *
   * @param instance the input instance
   * @return true if the filtered instance may now be
   * collected with output().
   * @exception IllegalStateException if no input format has been set
   */
  public boolean input(Instance instance) {

    if (getInputFormat() == null) {
      throw new IllegalStateException("No input instance format defined");
    }
    if (m_NewBatch) {
      resetQueue();
      m_NewBatch = false;
    }
    if ((m_Indices != null) || 
	(getInputFormat().classAttribute().isNominal())) {
      convertInstance(instance);
      return true;
    }
    bufferInput(instance);
    return false;
  }

  /**
   * Signify that this batch of input to the filter is finished. 
   * If the filter requires all instances prior to filtering,
   * output() may now be called to retrieve the filtered instances.
   *
   * @return true if there are instances pending output
   * @exception IllegalStateException if no input structure has been defined
   */
  public boolean batchFinished() {

    if (getInputFormat() == null) {
      throw new IllegalStateException("No input instance format defined");
    }
    if ((m_Indices == null) && 
	(getInputFormat().classAttribute().isNumeric())) {
      computeAverageClassValues();
      setOutputFormat();

      // Convert pending input instances

      for(int i = 0; i < getInputFormat().numInstances(); i++) {
	convertInstance(getInputFormat().instance(i));
      }
    } 
    flushInput();

    m_NewBatch = true;
    return (numPendingOutput() != 0);
  }

  /**
   * Returns an enumeration describing the available options.
   *
   * @return an enumeration of all the available options.
   */
  public Enumeration listOptions() {

    Vector newVector = new Vector(1);

    newVector.addElement(new Option(
	      "\tSets if binary attributes are to be coded as nominal ones.",
	      "N", 0, "-N"));

    return newVector.elements();
  }


  /**
   * Parses the options for this object. Valid options are: <p>
   *
   * -N <br>
   * If binary attributes are to be coded as nominal ones.<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 {
    
    setBinaryAttributesNominal(Utils.getFlag('N', options));

    if (getInputFormat() != null)
      setInputFormat(getInputFormat());
  }

  /**
   * Gets the current settings of the filter.
   *
   * @return an array of strings suitable for passing to setOptions
   */
  public String [] getOptions() {

    String [] options = new String [1];
    int current = 0;

    if (getBinaryAttributesNominal()) {
      options[current++] = "-N";
    }

    while (current < options.length) {
      options[current++] = "";
    }
    return options;
  }
    
  /**
   * Returns the tip text for this property
   *
   * @return tip text for this property suitable for
   * displaying in the explorer/experimenter gui
   */
  public String binaryAttributesNominalTipText() {
    return "Whether resulting binary attributes will be nominal.";
  }

  /**
   * Gets if binary attributes are to be treated as nominal ones.
   *
   * @return true if binary attributes are to be treated as nominal ones
   */
  public boolean getBinaryAttributesNominal() {

    return !m_Numeric;
  }

  /**
   * Sets if binary attributes are to be treates as nominal ones.
   *
   * @param bool true if binary attributes are to be treated as nominal ones
   */
  public void setBinaryAttributesNominal(boolean bool) {

    m_Numeric = !bool;
  }

  /** Computes average class values for each attribute and value */
  private void computeAverageClassValues() {
    
    double totalCounts, sum;
    Instance instance;
    double [] counts;

    double [][] avgClassValues = new double[getInputFormat().numAttributes()][0];
    m_Indices = new int[getInputFormat().numAttributes()][0];
    for (int j = 0; j < getInputFormat().numAttributes(); j++) {
      Attribute att = getInputFormat().attribute(j);
      if (att.isNominal()) {
	avgClassValues[j] = new double [att.numValues()];
	counts = new double [att.numValues()];
	for (int i = 0; i < getInputFormat().numInstances(); i++) {
	  instance = getInputFormat().instance(i);
	  if (!instance.classIsMissing() && 
	      (!instance.isMissing(j))) {
	    counts[(int)instance.value(j)] += instance.weight();
	    avgClassValues[j][(int)instance.value(j)] += 
	      instance.weight() * instance.classValue();
	  }
	}
	sum = Utils.sum(avgClassValues[j]);
	totalCounts = Utils.sum(counts);
	if (Utils.gr(totalCounts, 0)) {