removepercentage.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.
 */

/*
 *    RemovePercentage.java
 *    Copyright (C) 2002 Richard Kirkby
 *
 */


package weka.filters.unsupervised.instance;

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

/**
 * This filter outputs a given percentage of a dataset.
 *
 * Valid options are: <p>
 *
 * -V <br>
 * Specifies if inverse of selection is to be output.<p>
 *
 * -P percentage <br>
 * The percentage of instances to select. (default 50)<p>
 *
 * @author Richard Kirkby ([e-mail])
 * @author Eibe Frank ([e-mail])
 * @version $Revision: 1.1.1.1 $ 
*/
public class RemovePercentage extends Filter
  implements UnsupervisedFilter, OptionHandler {

  /** Percentage of instances to select. */
  private int m_Percentage = 50;

  /** Indicates if inverse of selection is to be output. */
  private boolean m_Inverse = false;

  /**
   * Gets 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(
              "\tSpecifies percentage of instances to select. (default 50)\n",
              "P", 1, "-P <percentage>"));

    newVector.addElement(new Option(
	      "\tSpecifies if inverse of selection is to be output.\n",
	      "V", 0, "-V"));

    return newVector.elements();
  }

  /**
   * Parses the options for this object. Valid options are: <p>
   *
   * -P percentage <br>
   * The percentage of instances to select. (default 50)<p>
   *
   * -V <br>
   * Specifies if inverse of selection is to be output.<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 percent = Utils.getOption('P', options);
    if (percent.length() != 0) {
      setPercentage(Integer.parseInt(percent));
    } else {
      setPercentage(50);
    }
    setInvertSelection(Utils.getFlag('V', 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 [5];
    int current = 0;

    options[current++] = "-P"; options[current++] = "" + getPercentage();
    if (getInvertSelection()) {
      options[current++] = "-V";
    }

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

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

    return "A filter that outputs a given percentage of a dataset.";
  }

  /**
   * Returns the tip text for this property
   *
   * @return tip text for this property suitable for
   * displaying in the explorer/experimenter gui
   */
  public String percentageTipText() {

    return "The percentage of the data to select.";
  }

  /**
   * Gets the percentage of instances to select.
   * 
   * @return the percentage.
   */
  public int getPercentage() {

    return m_Percentage;
  }

  /**
   * Sets the percentage of intances to select.
   *
   * @param percent the percentage
   * @exception IllegalArgumentException if percenatge out of range
   */
  public void setPercentage(int percent) {

    if (percent < 0 || percent > 100) {
      throw new IllegalArgumentException("Percentage must be between 0 and 100.");
    }
    m_Percentage = percent;
  }

  /**
   * Returns the tip text for this property
   *
   * @return tip text for this property suitable for
   * displaying in the explorer/experimenter gui
   */
  public String invertSelectionTipText() {

    return "Whether to invert the selection.";
  }

  /**
   * Gets if selection is to be inverted.
   *
   * @return true if the selection is to be inverted
   */
  public boolean getInvertSelection() {

    return m_Inverse;
  }

  /**
   * Sets if selection is to be inverted.
   *
   * @param inverse true if inversion is to be performed
   */
  public void setInvertSelection(boolean inverse) {
    
    m_Inverse = inverse;
  }

  /**
   * 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 because outputFormat can be collected immediately
   * @exception Exception if the input format can't be set successfully
   */  
  public boolean setInputFormat(Instances instanceInfo) throws Exception {

    super.setInputFormat(instanceInfo);
    setOutputFormat(instanceInfo);
    return true;
  }

  /**
   * Signify that this batch of input to the filter is
   * finished. 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");
    }

    // Push instances for output into output queue
    Instances toFilter = getInputFormat();
    int cutOff = toFilter.numInstances() * m_Percentage / 100;

    if (!m_Inverse) {
      for (int i = 0; i < cutOff; i++) {
	push(toFilter.instance(i));
      }
    } else {
      for (int i = cutOff; i < toFilter.numInstances(); i++) {
	push(toFilter.instance(i));
      }
    }
    m_NewBatch = true;
    return (numPendingOutput() != 0);
  }

  /**
   * Main method for testing this class.
   *
   * @param argv should contain arguments to the filter: use -h for help
   */
  public static void main(String [] argv) {

    try {
      if (Utils.getFlag('b', argv)) {
 	Filter.batchFilterFile(new RemovePercentage(), argv);
      } else {
	Filter.filterFile(new RemovePercentage(), argv);
      }
    } catch (Exception ex) {
      System.out.println(ex.getMessage());
    }
  }
}