third-party/net.sf.jung2/src/main/java/edu/uci/ics/jung/algorithms/scoring/util/ScoringUtils.java

   1 /*
   2  * Created on Jul 12, 2007
   3  *
   4  * Copyright (c) 2007, the JUNG Project and the Regents of the University
   5  * of California
   6  * All rights reserved.
   7  *
   8  * This software is open-source under the BSD license; see either
   9  * "license.txt" or
  10  * http://jung.sourceforge.net/license.txt for a description.
  11  */
  12 package edu.uci.ics.jung.algorithms.scoring.util;
  13
  14 import java.util.Collection;
  15
  16 import org.apache.commons.collections15.Transformer;
  17
  18 import edu.uci.ics.jung.algorithms.scoring.HITS;
  19
  20 /**
  21  * Methods for assigning values (to be interpreted as prior probabilities) to vertices in the context
  22  * of random-walk-based scoring algorithms.
  23  */
  24 public class ScoringUtils
  25 {
  26     /**
  27      * Assigns a probability of 1/<code>roots.size()</code> to each of the elements of <code>roots</code>.
  28      * @param <V> the vertex type
  29      * @param roots the vertices to be assigned nonzero prior probabilities
  30      * @return
  31      */
  32     public static <V> Transformer<V, Double> getUniformRootPrior(Collection<V> roots)
  33     {
  34         final Collection<V> inner_roots = roots;
  35         Transformer<V, Double> distribution = new Transformer<V, Double>()
  36         {
  37             public Double transform(V input)
  38             {
  39                 if (inner_roots.contains(input))
  40                     return new Double(1.0 / inner_roots.size());
  41                 else
  42                     return 0.0;
  43             }
  44         };
  45
  46         return distribution;
  47     }
  48
  49     /**
  50      * Returns a Transformer that hub and authority values of 1/<code>roots.size()</code> to each
  51      * element of <code>roots</code>.
  52      * @param <V> the vertex type
  53      * @param roots the vertices to be assigned nonzero scores
  54      * @return a Transformer that assigns uniform prior hub/authority probabilities to each root
  55      */
  56     public static <V> Transformer<V, HITS.Scores> getHITSUniformRootPrior(Collection<V> roots)
  57     {
  58         final Collection<V> inner_roots = roots;
  59         Transformer<V, HITS.Scores> distribution =
  60                 new Transformer<V, HITS.Scores>()
  61         {
  62             public HITS.Scores transform(V input)
  63             {
  64                 if (inner_roots.contains(input))
  65                     return new HITS.Scores(1.0 / inner_roots.size(), 1.0 / inner_roots.size());
  66                 else
  67                     return new HITS.Scores(0.0, 0.0);
  68             }
  69         };
  70         return distribution;
  71     }
  72 }