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.
   */
  
  /*
   *    ManhattanDistance.java
   *    Copyright (C) 2007 University of Waikato, Hamilton, New Zealand
   *
   */
  
  package weka.core;
  
  import weka.core.TechnicalInformation.Field;
  import weka.core.TechnicalInformation.Type;
  
  /**
   <!-- globalinfo-start -->
   * Implements the Manhattan distance (or Taxicab geometry). The distance between two points is the sum of the (absolute) differences of their coordinates.<br/>
   * <br/>
   * For more information, see:<br/>
   * <br/>
   * Wikipedia. Taxicab geometry. URL http://en.wikipedia.org/wiki/Taxicab_geometry.
   * <p/>
   <!-- globalinfo-end -->
   *
   <!-- technical-bibtex-start -->
   * BibTeX:
   * <pre>
   * &#64;misc{missing_id,
   *    author = {Wikipedia},
   *    title = {Taxicab geometry},
   *    URL = {http://en.wikipedia.org/wiki/Taxicab_geometry}
   * }
   * </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: 5953 $
   */
  public class ManhattanDistance
    extends NormalizableDistance
    implements TechnicalInformationHandler {
    
    /** for serialization. */
    private static final long serialVersionUID = 6783782554224000243L;
  
    /**
     * Constructs an Manhattan Distance object, Instances must be still set.
     */
    public ManhattanDistance() {
      super();
    }
  
    /**
     * Constructs an Manhattan Distance object and automatically initializes the
     * ranges.
     * 
     * @param data 	the instances the distance function should work on
     */
    public ManhattanDistance(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 Manhattan distance (or Taxicab geometry). The distance "
        + "between two points is the sum of the (absolute) differences of their "
        + "coordinates.\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, "Taxicab geometry");
      result.setValue(Field.URL, "http://en.wikipedia.org/wiki/Taxicab_geometry");
  
      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;
      result += Math.abs(diff);
      
      return result;
    }
    
    /**
     * Returns the revision string.
     * 
     * @return		the revision
     */
    public String getRevision() {
      return RevisionUtils.extract("$Revision: 5953 $");
    }
  }
  