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• Randomize.java

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weka.filters.unsupervised.instance.Randomize Maven / Gradle / Ivy

/*
 *   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 3 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, see .
 */

/*
 *    Randomize.java
 *    Copyright (C) 1999-2012 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.filters.unsupervised.instance;

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

import weka.core.Capabilities;
import weka.core.Capabilities.Capability;
import weka.core.Instance;
import weka.core.Instances;
import weka.core.Option;
import weka.core.OptionHandler;
import weka.core.RevisionUtils;
import weka.core.Utils;
import weka.filters.Filter;
import weka.filters.UnsupervisedFilter;

/**
 *  Randomly shuffles the order of instances passed
 * through it. The random number generator is reset with the seed value whenever
 * a new set of instances is passed in.
 * 

 * 
 * 
 *  Valid options are:
 * 

 * 
 * 
 * -S <num>
 *  Specify the random number seed (default 42)
 * 
 * 
 * 
 * 
 * @author Len Trigg ([email protected])
 * @version $Revision: 12037 $
 */
public class Randomize extends Filter implements UnsupervisedFilter,
  OptionHandler {

  /** for serialization */
  static final long serialVersionUID = 8854479785121877582L;

  /** The random number seed */
  protected int m_Seed = 42;

  /** The current random number generator */
  protected Random m_Random;

  /**
   * Returns a string describing this classifier
   * 
   * @return a description of the classifier suitable for displaying in the
   *         explorer/experimenter gui
   */
  public String globalInfo() {
    return "Randomly shuffles the order of instances passed through it. "
      + "The random number generator is reset with the seed value whenever "
      + "a new set of instances is passed in.";
  }

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

    Vector newVector = new Vector(1);

    newVector.addElement(new Option(
      "\tSpecify the random number seed (default 42)", "S", 1, "-S "));

    return newVector.elements();
  }

  /**
   * Parses a given list of options.
   * 

   * 
   *  Valid options are:
   * 

   * 
   * 
   * -S <num>
   *  Specify the random number seed (default 42)
   * 
   * 
   * 
   * 
   * @param options the list of options as an array of strings
   * @throws Exception if an option is not supported
   */
  @Override
  public void setOptions(String[] options) throws Exception {

    String seedString = Utils.getOption('S', options);
    if (seedString.length() != 0) {
      setRandomSeed(Integer.parseInt(seedString));
    } else {
      setRandomSeed(42);
    }

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

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

    Vector options = new Vector();

    options.add("-S");
    options.add("" + getRandomSeed());

    return options.toArray(new String[0]);
  }

  /**
   * Returns the tip text for this property
   * 
   * @return tip text for this property suitable for displaying in the
   *         explorer/experimenter gui
   */
  public String randomSeedTipText() {
    return "Seed for the random number generator.";
  }

  /**
   * Get the random number generator seed value.
   * 
   * @return random number generator seed value.
   */
  public int getRandomSeed() {

    return m_Seed;
  }

  /**
   * Set the random number generator seed value.
   * 
   * @param newRandomSeed value to use as the random number generator seed.
   */
  public void setRandomSeed(int newRandomSeed) {

    m_Seed = newRandomSeed;
  }

  /**
   * Returns the Capabilities of this filter.
   * 
   * @return the capabilities of this object
   * @see Capabilities
   */
  @Override
  public Capabilities getCapabilities() {
    Capabilities result = super.getCapabilities();
    result.disableAll();

    // attributes
    result.enableAllAttributes();
    result.enable(Capability.MISSING_VALUES);

    // class
    result.enableAllClasses();
    result.enable(Capability.MISSING_CLASS_VALUES);
    result.enable(Capability.NO_CLASS);

    return result;
  }

  /**
   * 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
   * @throws Exception if format cannot be processed
   */
  @Override
  public boolean setInputFormat(Instances instanceInfo) throws Exception {

    super.setInputFormat(instanceInfo);
    setOutputFormat(instanceInfo);
    m_Random = new Random(m_Seed);
    return true;
  }

  /**
   * 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().
   * @throws IllegalStateException if no input structure has been defined
   */
  @Override
  public boolean input(Instance instance) {

    if (getInputFormat() == null) {
      throw new IllegalStateException("No input instance format defined");
    }
    if (m_NewBatch) {
      resetQueue();
      m_NewBatch = false;
    }
    if (isFirstBatchDone()) {
      push(instance);
      return true;
    } else {
      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. Any subsequent instances filtered should
   * be filtered based on setting obtained from the first batch (unless the
   * setInputFormat has been re-assigned or new options have been set). This
   * implementation randomizes all the instances received in the batch.
   * 
   * @return true if there are instances pending output
   * @throws IllegalStateException if no input format has been set.
   */
  @Override
  public boolean batchFinished() {

    if (getInputFormat() == null) {
      throw new IllegalStateException("No input instance format defined");
    }

    if (!isFirstBatchDone()) {
      getInputFormat().randomize(m_Random);
    }
    for (int i = 0; i < getInputFormat().numInstances(); i++) {
      push(getInputFormat().instance(i), false); // No need to copy because of bufferInput()
    }
    flushInput();

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

  /**
   * Returns the revision string.
   * 
   * @return the revision
   */
  @Override
  public String getRevision() {
    return RevisionUtils.extract("$Revision: 12037 $");
  }

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