1 | #region License Information
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2 | /* HeuristicLab
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3 | * Copyright (C) 2002-2013 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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4 | *
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5 | * This file is part of HeuristicLab.
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6 | *
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7 | * HeuristicLab is free software: you can redistribute it and/or modify
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8 | * it under the terms of the GNU General Public License as published by
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9 | * the Free Software Foundation, either version 3 of the License, or
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10 | * (at your option) any later version.
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11 | *
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12 | * HeuristicLab is distributed in the hope that it will be useful,
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13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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15 | * GNU General Public License for more details.
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16 | *
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17 | * You should have received a copy of the GNU General Public License
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18 | * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
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19 | */
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20 | #endregion
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21 |
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22 | using System.Collections.Generic;
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23 | using System.Linq;
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24 |
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25 | namespace HeuristicLab.Analysis.AlgorithmBehavior.Analyzers {
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26 | public static class ConvexHullMeasures {
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27 | //Calculates the volumne of a d-simplex
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28 | private static double CalculateSimplexVolume(List<double[]> simplex) {
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29 | double[,] diffs = new double[simplex.Count, simplex.Count];
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30 |
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31 | for (int i = 0; i < simplex.Count; i++) {
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32 | for (int j = 0; j < simplex.Count; j++) {
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33 | diffs[i, j] = simplex[i].EuclideanDistance(simplex[j]);
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34 | }
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35 | }
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36 |
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37 | double det = alglib.rmatrixdet(diffs);
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38 | double result = det / simplex[0].Count().Fact();
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39 |
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40 | return result;
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41 | }
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42 |
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43 | //calculate center for boundary triangulation (slowwwww.....)
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44 | private static double[] CalculateInnerPoint(List<double[]> hyperHull) {
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45 | double[] result = new double[hyperHull[0].Count()];
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46 |
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47 | for (int i = 0; i < hyperHull[0].Count(); i++) {
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48 | result[i] = (hyperHull.Max(x => x[i]) + hyperHull.Min(x => x[i])) / 2.0;
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49 | }
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50 |
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51 | return result;
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52 | }
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53 |
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54 | //calculates the volume of a convex d-polytope
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55 | //decomposition based on boundary triangulation
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56 | public static double CalculateVolume(List<double[]> convexHull) {
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57 | double[] innerPoint = CalculateInnerPoint(convexHull);
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58 | double volume = 0.0;
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59 |
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60 | for (int i = 0; i < convexHull.Count - 1; i += 2) {
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61 | List<double[]> simplex = new List<double[]>();
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62 | simplex.Add(innerPoint);
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63 | simplex.Add(convexHull[i]);
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64 | simplex.Add(convexHull[i + 1]);
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65 | volume += CalculateSimplexVolume(simplex);
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66 | }
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67 | return volume;
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68 | }
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69 | }
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70 | }
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