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.
   */
  
  /*
   *    RemovePercentage.java
   *    Copyright (C) 2002 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.Vector;
  
  /**
   <!-- globalinfo-start -->
   * A filter that removes a given percentage of a dataset.
   * <p/>
   <!-- globalinfo-end -->
   * 
   <!-- options-start -->
   * Valid options are: <p/>
   * 
   * <pre> -P &lt;percentage&gt;
   *  Specifies percentage of instances to select. (default 50)
   * </pre>
   * 
   * <pre> -V
   *  Specifies if inverse of selection is to be output.
   * </pre>
   * 
   <!-- options-end -->
   *
   * @author Richard Kirkby (eibe@cs.waikato.ac.nz)
   * @author Eibe Frank (eibe@cs.waikato.ac.nz)
   * @version $Revision: 5499 $ 
  */
  public class RemovePercentage 
    extends Filter
    implements UnsupervisedFilter, OptionHandler {
  
    /** for serialization */
    static final long serialVersionUID = 2150341191158533133L;
    
    /** Percentage of instances to select. */
    private double 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 a given list of options. <p/>
     * 
     <!-- options-start -->
     * Valid options are: <p/>
     * 
     * <pre> -P &lt;percentage&gt;
     *  Specifies percentage of instances to select. (default 50)
     * </pre>
     * 
     * <pre> -V
     *  Specifies if inverse of selection is to be output.
     * </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 percent = Utils.getOption('P', options);
      if (percent.length() != 0) {
        setPercentage(Double.parseDouble(percent));
      } else {
        setPercentage(50.0);
      }
      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 removes 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 double getPercentage() {
  
      return m_Percentage;
    }
  
    /**
     * Sets the percentage of intances to select.
     *
     * @param percent the percentage
     * @throws IllegalArgumentException if percentage out of range
     */
    public void setPercentage(double 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;
    }
  
    /** 
     * 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 because outputFormat can be collected immediately
     * @throws Exception if the input format can't be set successfully
     */  
    public boolean setInputFormat(Instances instanceInfo) throws Exception {
  
      super.setInputFormat(instanceInfo);
      setOutputFormat(instanceInfo);
      return true;
    }
    
    /**
     * Input an instance for filtering. Ordinarily the instance is processed
     * and made available for output immediately. Some filters require all
     * 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 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 (isFirstBatchDone()) {
         push(instance);
         return true;
       } 
       else {
         bufferInput(instance);
         return false;
       }
    }
  
    /**
     * 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
     * @throws 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 = (int) Math.round(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));
        }
      }
      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 RemovePercentage(), argv);
    }
  }
  