content: /*
   *    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.
   */
  
  /*
   *    Randomize.java
   *    Copyright (C) 1999 University of Waikato, Hamilton, New Zealand
   *
   */
  
  
  package weka.filters.unsupervised.instance;
  
  import weka.core.Capabilities;
  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.core.Capabilities.Capability;
  import weka.filters.Filter;
  import weka.filters.UnsupervisedFilter;
  
  import java.util.Enumeration;
  import java.util.Random;
  import java.util.Vector;
  
  /** 
   <!-- globalinfo-start -->
   * 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.
   * <p/>
   <!-- globalinfo-end -->
   * 
   <!-- options-start -->
   * Valid options are: <p/>
   * 
   * <pre> -S &lt;num&gt;
   *  Specify the random number seed (default 42)</pre>
   * 
   <!-- options-end -->
   *
   * @author Len Trigg (trigg@cs.waikato.ac.nz)
   * @version $Revision: 5499 $
   */
  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.
     */
    public Enumeration listOptions() {
  
      Vector newVector = new Vector(1);
  
      newVector.addElement(new Option(
                "\tSpecify the random number seed (default 42)",
                "S", 1, "-S <num>"));
  
      return newVector.elements();
    }
  
  
    /**
     * Parses a given list of options. <p/>
     * 
     <!-- options-start -->
     * Valid options are: <p/>
     * 
     * <pre> -S &lt;num&gt;
     *  Specify the random number seed (default 42)</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 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
     */
    public String [] getOptions() {
  
      String [] options = new String [2];
      int current = 0;
  
      options[current++] = "-S"; options[current++] = "" + getRandomSeed();
  
      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 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
     */
    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
     */
    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
     */
    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. 
     */
    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));
      }
      flushInput();
      
      m_NewBatch = true;
      m_FirstBatchDone = true;
      return (numPendingOutput() != 0);
    }
    
    /**
     * Returns the revision string.
     * 
     * @return		the revision
     */
    public String getRevision() {
      return RevisionUtils.extract("$Revision: 5499 $");
    }
  
    /**
     * 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);
    }
  }
  