src/main/java/jp/sourceforge/stigmata/birthmarks/comparators/ExtendedEditDistanceBirthmarkComparator.java

   1 package jp.sourceforge.stigmata.birthmarks.comparators;
   2
   3 /*
   4  * $Id$
   5  */
   6
   7 import jp.sourceforge.stigmata.Birthmark;
   8 import jp.sourceforge.stigmata.BirthmarkElement;
   9 import jp.sourceforge.stigmata.spi.BirthmarkSpi;
  10
  11 /**
  12  * calculate similarities between two birthmarks by edit distance
  13  * algorithm (levenshtein distance).
  14  *
  15  * @author Haruaki TAMADA
  16  * @version $Revision$
  17  */
  18 public class ExtendedEditDistanceBirthmarkComparator extends EditDistanceBirthmarkComparator{
  19     public ExtendedEditDistanceBirthmarkComparator(BirthmarkSpi spi){
  20         super(spi);
  21     }
  22
  23     public double compare(Birthmark b1, Birthmark b2) {
  24         if(!b1.getType().equals(b2.getType())){
  25             return Double.NaN;
  26         }
  27
  28         BirthmarkElement[] element1 = b1.getElements();
  29         BirthmarkElement[] element2 = b2.getElements();
  30         int[][] distance = createDistanceMatrics(element1, element2);
  31
  32         int length = element1.length;
  33         if(length > element2.length){
  34             length = element2.length;
  35         }
  36         int d = distance[element1.length][element2.length];
  37
  38         return (double)(1 - (d + Math.abs(element1.length - element2.length))) / length;
  39     }
  40 }