Changeset 14030 for branches/HeuristicLab.Problems.MultiObjectiveTestFunctions/HeuristicLab.Problems.MultiObjectiveTestFunctions/3.3/Calculators/GenerationalDistance.cs

Timestamp:

07/08/16 15:30:46 (8 years ago)

Author:

bwerth

Message:

#1087 several fixes according to the reviev comments in comment 31

File:

• branches/HeuristicLab.Problems.MultiObjectiveTestFunctions/HeuristicLab.Problems.MultiObjectiveTestFunctions/3.3/Calculators/GenerationalDistance.cs (modified) (1 diff)

branches/HeuristicLab.Problems.MultiObjectiveTestFunctions/HeuristicLab.Problems.MultiObjectiveTestFunctions/3.3/Calculators/GenerationalDistance.cs

@@ -26 +26 @@
 
   /// <summary>
-  /// The generational Distance is defined as the mean of a all d[i]^(1/p),
+  /// The generational Distance is defined as the pth-root of the sum of all d[i]^(p) divided by the size of the front
   ///  where d[i] is the minimal distance the ith point of the evaluated front has to any point in the optimal pareto front.   
+  ///  p is a dampening factor and is normally set to 1. 
+  ///  http://shodhganga.inflibnet.ac.in/bitstream/10603/15070/28/28_appendix_h.pdf
   /// </summary>
   public static class GenerationalDistance {
 
     public static double Calculate(IEnumerable<double[]> front, IEnumerable<double[]> optimalFront, double p) {
-      //TODO build a kd-tree, sort the array, do something intelligent here
       if (front == null || optimalFront == null) throw new ArgumentNullException("Fronts must not be null.");
       if (!front.Any()) throw new ArgumentException("Front must not be empty.");
       if (p == 0.0) throw new ArgumentException("p must not be 0.0.");
 
-      double sum = 0;
-      int c = 0;
-      foreach (double[] r in front) {
-        sum += Utilities.MinimumDistance(r, optimalFront);
-        c++;
-      }
 
-      return Math.Pow(sum, 1 / p) / c;
+      double sum = front.Select(r => Math.Pow(Utilities.MinimumDistance(r, optimalFront), p)).Sum();
+      return Math.Pow(sum, 1 / p) / front.Count();
     }