source: branches/HeuristicLab.Analysis.AlgorithmBehavior/HeuristicLab.Analysis.AlgorithmBehavior.Analyzers/3.3/ConvexHullMeasures.cs @ 10008

Last change on this file since 10008 was 10008, checked in by ascheibe, 7 years ago

#1886 added volume calculation for convex d-polytopes

File size: 2.7 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2013 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
4 *
5 * This file is part of HeuristicLab.
6 *
7 * HeuristicLab is free software: you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation, either version 3 of the License, or
10 * (at your option) any later version.
11 *
12 * HeuristicLab is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
19 */
20#endregion
21
22using System.Collections.Generic;
23using System.Linq;
24
25namespace HeuristicLab.Analysis.AlgorithmBehavior.Analyzers {
26  public static class ConvexHullMeasures {
27    //Calculates the volumne of a d-simplex
28    private static double CalculateSimplexVolume(List<double[]> hyperHull) {
29      double[,] diffs = new double[hyperHull.Count, hyperHull.Count];
30
31      for (int i = 0; i < hyperHull.Count; i++) {
32        for (int j = 0; j < hyperHull.Count; j++) {
33          diffs[i, j] = CalculateVectorDiff(hyperHull[i], hyperHull[j]);
34        }
35      }
36
37      double det = alglib.rmatrixdet(diffs);
38      double result = det / hyperHull[0].Count().Fact();
39
40      return result;
41    }
42
43    private static double CalculateVectorDiff(double[] vector1, double[] vector2) {
44      double result = 0.0;
45
46      for (int i = 0; i < vector1.Length; i++) {
47        result += vector1[i] - vector2[i];
48      }
49
50      return result;
51    }
52
53    //calculate inner point for boundary triangulation (slowwwww.....)
54    private static double[] CalculateInnerPoint(List<double[]> hyperHull) {
55      double[] result = new double[hyperHull[0].Count()];
56
57      for (int i = 0; i < hyperHull[0].Count(); i++) {
58        result[i] = hyperHull.Max(x => x[i]) - hyperHull.Min(x => x[i]);
59      }
60
61      return result;
62    }
63
64    //calculates the volume of a convex d-polytope
65    //decomposition based on boundary triangulation
66    public static double CalculateVolume(List<double[]> hyperHull) {
67      double[] innerPoint = CalculateInnerPoint(hyperHull);
68      double volume = 0.0;
69
70      for (int i = 0; i < hyperHull.Count - 1; i += 2) {
71        List<double[]> simplex = new List<double[]>();
72        simplex.Add(innerPoint);
73        simplex.Add(hyperHull[i]);
74        simplex.Add(hyperHull[i + 1]);
75        volume += CalculateSimplexVolume(simplex);
76      }
77      return volume;
78    }
79  }
80}
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