weka.core.ChebyshevDistance.java Source code

Introduction

Here is the source code for weka.core.ChebyshevDistance.java

Source

/*
 *   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 <http://www.gnu.org/licenses/>.
 */

/*
 *    ChebyshevDistance.java
 *    Copyright (C) 2007-2012 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.core;

import weka.core.TechnicalInformation.Field;
import weka.core.TechnicalInformation.Type;

/**
 <!-- globalinfo-start -->
 * Implements the Chebyshev distance. The distance between two vectors is the greatest of their differences along any coordinate dimension.<br/>
 * <br/>
 * For more information, see:<br/>
 * <br/>
 * Wikipedia. Chebyshev distance. URL http://en.wikipedia.org/wiki/Chebyshev_distance.
 * <p/>
 <!-- globalinfo-end -->
 *
 <!-- technical-bibtex-start -->
 * BibTeX:
 * <pre>
 * &#64;misc{missing_id,
 *    author = {Wikipedia},
 *    title = {Chebyshev distance},
 *    URL = {http://en.wikipedia.org/wiki/Chebyshev_distance}
 * }
 * </pre>
 * <p/>
 <!-- technical-bibtex-end -->
 *
 <!-- options-start -->
 * Valid options are: <p/>
 * 
 * <pre> -D
 *  Turns off the normalization of attribute 
 *  values in distance calculation.</pre>
 * 
 * <pre> -R &lt;col1,col2-col4,...&gt;
 *  Specifies list of columns to used in the calculation of the 
 *  distance. 'first' and 'last' are valid indices.
 *  (default: first-last)</pre>
 * 
 * <pre> -V
 *  Invert matching sense of column indices.</pre>
 * 
 <!-- options-end --> 
 *
 * @author Fracpete (fracpete at waikato dot ac dot nz)
 * @version $Revision$
 */
public class ChebyshevDistance extends NormalizableDistance implements TechnicalInformationHandler {

    /** for serialization. */
    private static final long serialVersionUID = -7739904999895461429L;

    /**
     * Constructs an Chebyshev Distance object, Instances must be still set.
     */
    public ChebyshevDistance() {
        super();
    }

    /**
     * Constructs an Chebyshev Distance object and automatically initializes the
     * ranges.
     * 
     * @param data    the instances the distance function should work on
     */
    public ChebyshevDistance(Instances data) {
        super(data);
    }

    /**
     * Returns a string describing this object.
     * 
     * @return       a description of the evaluator suitable for
     *          displaying in the explorer/experimenter gui
     */
    public String globalInfo() {
        return "Implements the Chebyshev distance. The distance between two vectors "
                + "is the greatest of their differences along any coordinate dimension.\n\n"
                + "For more information, see:\n\n" + getTechnicalInformation().toString();
    }

    /**
     * Returns an instance of a TechnicalInformation object, containing 
     * detailed information about the technical background of this class,
     * e.g., paper reference or book this class is based on.
     * 
     * @return       the technical information about this class
     */
    public TechnicalInformation getTechnicalInformation() {
        TechnicalInformation result;

        result = new TechnicalInformation(Type.MISC);
        result.setValue(Field.AUTHOR, "Wikipedia");
        result.setValue(Field.TITLE, "Chebyshev distance");
        result.setValue(Field.URL, "http://en.wikipedia.org/wiki/Chebyshev_distance");

        return result;
    }

    /**
     * Updates the current distance calculated so far with the new difference
     * between two attributes. The difference between the attributes was 
     * calculated with the difference(int,double,double) method.
     * 
     * @param currDist   the current distance calculated so far
     * @param diff   the difference between two new attributes
     * @return      the update distance
     * @see      #difference(int, double, double)
     */
    protected double updateDistance(double currDist, double diff) {
        double result;

        result = currDist;

        diff = Math.abs(diff);
        if (diff > result)
            result = diff;

        return result;
    }

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