• Home
• nz.ac.waikato.cms.weka
• weka-dev
• 3.9.4
• source code
• RemoveUseless.java

×

Project download

Many resources are needed to download a project. Please understand that we have to compensate our server costs. Thank you in advance.
Project price only 1 $

You can buy this project and download/modify it how often you want.

weka.filters.unsupervised.attribute.RemoveUseless 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 .
 */

/*
 *    RemoveUseless.java
 *    Copyright (C) 2002-2012 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.filters.unsupervised.attribute;

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

import weka.core.*;
import weka.core.Capabilities.Capability;
import weka.filters.Filter;
import weka.filters.UnsupervisedFilter;

/**
 *  This filter removes attributes that do not vary at
 * all or that vary too much. All constant attributes are deleted automatically,
 * along with any that exceed the maximum percentage of variance parameter. The
 * maximum variance test is only applied to nominal attributes.
 * 

 * 
 * 
 *  Valid options are:
 * 

 * 
 * 
 * -M <max variance %>
 *  Maximum variance percentage allowed (default 99). Specifically, if
 *  (number_of_distinct_values / total_number_of_values * 100)
 *  is greater than this value, then the attribute will be removed.
 * 
 * 
 * 
 * 
 * @author Richard Kirkby ([email protected])
 * @version $Revision: 14508 $
 */
public class RemoveUseless extends Filter implements UnsupervisedFilter,
  OptionHandler, WeightedInstancesHandler, WeightedAttributesHandler {

  /** for serialization */
  static final long serialVersionUID = -8659417851407640038L;

  /** The filter used to remove attributes */
  protected Remove m_removeFilter = null;

  /** The type of attribute to delete */
  protected double m_maxVariancePercentage = 99.0;

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

    // attributes
    result.enable(Capability.NOMINAL_ATTRIBUTES);
    result.enable(Capability.NUMERIC_ATTRIBUTES);
    result.enable(Capability.DATE_ATTRIBUTES);
    result.enable(Capability.STRING_ATTRIBUTES);
    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 the inputFormat can't be set successfully
   */
  @Override
  public boolean setInputFormat(Instances instanceInfo) throws Exception {

    super.setInputFormat(instanceInfo);
    m_removeFilter = null;
    return false;
  }

  /**
   * Input an instance for filtering.
   * 
   * @param instance the input instance
   * @return true if the filtered instance may now be collected with output().
   */
  @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 (m_removeFilter != null) {
      m_removeFilter.input(instance);
      Instance processed = m_removeFilter.output();

      copyValues(processed, false, instance.dataset(), outputFormatPeek());

      push(processed, false); // No need to copy
      return true;
    }
    bufferInput(instance);
    return false;
  }

  /**
   * Signify that this batch of input to the filter is finished.
   * 
   * @return true if there are instances pending output
   * @throws Exception if no input format defined
   */
  @Override
  public boolean batchFinished() throws Exception {

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

      // establish attributes to remove from first batch

      Instances toFilter = getInputFormat();
      int[] attsToDelete = new int[toFilter.numAttributes()];
      int numToDelete = 0;
      for (int i = 0; i < toFilter.numAttributes(); i++) {
        if (i == toFilter.classIndex()) {
          continue; // skip class
        }
        AttributeStats stats = toFilter.attributeStats(i);
        if (stats.missingCount == toFilter.numInstances()) {
          attsToDelete[numToDelete++] = i;
        } else if (stats.distinctCount < 2) {
          // remove constant attributes
          attsToDelete[numToDelete++] = i;
        } else if (toFilter.attribute(i).isNominal()) {
          // remove nominal attributes that vary too much
          double variancePercent = (double) stats.distinctCount
            / (double) (stats.totalCount - stats.missingCount) * 100.0;
          if (variancePercent > m_maxVariancePercentage) {
            attsToDelete[numToDelete++] = i;
          }
        }
      }

      int[] finalAttsToDelete = new int[numToDelete];
      System.arraycopy(attsToDelete, 0, finalAttsToDelete, 0, numToDelete);

      m_removeFilter = new Remove();
      m_removeFilter.setAttributeIndicesArray(finalAttsToDelete);
      m_removeFilter.setInvertSelection(false);
      m_removeFilter.setInputFormat(toFilter);

      for (int i = 0; i < toFilter.numInstances(); i++) {
        m_removeFilter.input(toFilter.instance(i));
      }
      m_removeFilter.batchFinished();

      Instance processed;
      Instances outputDataset = m_removeFilter.getOutputFormat();

      // restore old relation name to hide attribute filter stamp
      outputDataset.setRelationName(toFilter.relationName());

      setOutputFormat(outputDataset);
      while ((processed = m_removeFilter.output()) != null) {
        processed.setDataset(outputDataset);
        push(processed, false); // No need to copy
      }
    }
    flushInput();

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

  /**
   * 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(
      "\tMaximum variance percentage allowed (default 99). Specifically, if"
                + "\t(number_of_distinct_values / total_number_of_values * 100)"
                + "\tis greater than this value, then the attribute will be removed.", "M", 1,
      "-M "));

    return newVector.elements();
  }

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

   * 
   *  Valid options are:
   * 

   * 
   * 
   * -M <max variance %>
   *  Maximum variance percentage allowed (default 99). Specifically, if
   *  (number_of_distinct_values / total_number_of_values * 100)
   *  is greater than this value, then the attribute will be removed.
   * 
   * 
   * 
   * 
   * @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 mString = Utils.getOption('M', options);
    if (mString.length() != 0) {
      setMaximumVariancePercentageAllowed((int) Double.valueOf(mString)
        .doubleValue());
    } else {
      setMaximumVariancePercentageAllowed(99.0);
    }

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

    Utils.checkForRemainingOptions(options);
  }

  /**
   * 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("-M");
    options.add("" + getMaximumVariancePercentageAllowed());

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

  /**
   * Returns a string describing this filter
   * 
   * @return a description of the filter suitable for displaying in the
   *         explorer/experimenter gui
   */
  public String globalInfo() {
    return "This filter removes attributes that do not vary at all or that vary "
      + "too much. All constant attributes are deleted automatically, along "
      + "with any that exceed the maximum percentage of variance parameter. "
      + "The maximum variance test is only applied to nominal attributes.";
  }

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

    return "Set the threshold for the highest variance allowed before a nominal attribute will be deleted. "
      + "Specifically, if (number_of_distinct_values / total_number_of_values * 100)"
      + " is greater than this value, then the attribute will be removed.";
  }

  /**
   * Sets the maximum variance attributes are allowed to have before they are
   * deleted by the filter.
   * 
   * @param maxVariance the maximum variance allowed, specified as a percentage
   */
  public void setMaximumVariancePercentageAllowed(double maxVariance) {

    m_maxVariancePercentage = maxVariance;
  }

  /**
   * Gets the maximum variance attributes are allowed to have before they are
   * deleted by the filter.
   * 
   * @return the maximum variance allowed, specified as a percentage
   */
  public double getMaximumVariancePercentageAllowed() {

    return m_maxVariancePercentage;
  }

  /**
   * Returns the revision string.
   * 
   * @return the revision
   */
  @Override
  public String getRevision() {
    return RevisionUtils.extract("$Revision: 14508 $");
  }

  /**
   * 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 RemoveUseless(), argv);
  }
}