1 | #region License Information
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2 | /* HeuristicLab
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3 | * Copyright (C) 2002-2012 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;
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23 | using HeuristicLab.Common;
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24 | using HeuristicLab.Core;
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25 | using HeuristicLab.Encodings.PermutationEncoding;
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26 | using HeuristicLab.Optimization.Operators;
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27 |
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28 | namespace HeuristicLab.Problems.TravelingSalesman {
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29 | /// <summary>
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30 | /// An operator that performs similarity calculation between two traveling salesman solutions.
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31 | /// </summary>
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32 | /// <remarks>
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33 | /// The operator calculates the similarity based on the number of edges the two solutions have in common.
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34 | /// </remarks>
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35 | [Item("TSPSimilarityCalculator", "An operator that performs similarity calculation between two traveling salesman solutions. The operator calculates the similarity based on the number of edges the two solutions have in common.")]
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36 | public sealed class TSPSimilarityCalculator : SingleObjectiveSolutionSimilarityCalculator {
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37 | private TSPSimilarityCalculator(bool deserializing) : base(deserializing) { }
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38 | private TSPSimilarityCalculator(TSPSimilarityCalculator original, Cloner cloner) : base(original, cloner) { }
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39 | public TSPSimilarityCalculator() : base() { }
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40 |
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41 | public override IDeepCloneable Clone(Cloner cloner) {
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42 | return new TSPSimilarityCalculator(this, cloner);
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43 | }
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44 |
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45 | public static double CalculateSimilarity(Permutation left, Permutation right) {
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46 | if (left == null || right == null)
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47 | throw new ArgumentException("Cannot calculate similarity because one of the provided solutions or both are null.");
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48 | if (left.PermutationType != right.PermutationType)
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49 | throw new ArgumentException("Cannot calculate similarity because the provided solutions have different types.");
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50 | if (left.Length != right.Length)
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51 | throw new ArgumentException("Cannot calculate similarity because the provided solutions have different lengths.");
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52 | if (object.ReferenceEquals(left, right)) return 1.0;
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53 |
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54 | switch (left.PermutationType) {
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55 | case PermutationTypes.Absolute:
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56 | return CalculateAbsolute(left, right);
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57 | case PermutationTypes.RelativeDirected:
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58 | return CalculateRelativeDirected(left, right);
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59 | case PermutationTypes.RelativeUndirected:
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60 | return CalculateRelativeUndirected(left, right);
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61 | default:
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62 | throw new InvalidOperationException("unknown permutation type");
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63 | }
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64 | }
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65 |
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66 | private static double CalculateAbsolute(Permutation left, Permutation right) {
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67 | double similarity = 0.0;
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68 | for (int i = 0; i < left.Length; i++)
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69 | if (left[i] == right[i]) similarity++;
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70 |
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71 | return similarity / left.Length;
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72 | }
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73 |
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74 | private static double CalculateRelativeDirected(Permutation left, Permutation right) {
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75 | int[] edges = new int[right.Length];
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76 | for (int i = 0; i < right.Length; i++)
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77 | edges[right[i]] = right[(i + 1) % right.Length];
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78 |
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79 | double similarity = 0.0;
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80 | for (int i = 0; i < left.Length; i++)
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81 | if (left[(i + 1) % left.Length] == edges[left[i]]) similarity++;
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82 |
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83 | return similarity / left.Length;
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84 | }
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85 |
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86 | private static double CalculateRelativeUndirected(Permutation left, Permutation right) {
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87 | int[] edgesR = CalculateEdgesVector(right);
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88 | int[] edgesL = CalculateEdgesVector(left);
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89 |
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90 | double similarity = 0.0;
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91 | for (int i = 0; i < left.Length; i++) {
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92 | if ((edgesL[i] == edgesR[i]) || (edgesL[edgesR[i]] == i))
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93 | similarity++;
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94 | }
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95 |
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96 | return similarity / left.Length;
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97 | }
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98 |
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99 | private static int[] CalculateEdgesVector(Permutation permutation) {
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100 | // transform path representation into adjacency representation
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101 | int[] edgesVector = new int[permutation.Length];
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102 | for (int i = 0; i < permutation.Length - 1; i++)
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103 | edgesVector[permutation[i]] = permutation[i + 1];
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104 | edgesVector[permutation[permutation.Length - 1]] = permutation[0];
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105 | return edgesVector;
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106 | }
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107 |
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108 | public override double CalculateSolutionSimilarity(IScope leftSolution, IScope rightSolution) {
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109 | var sol1 = leftSolution.Variables[SolutionVariableName].Value as Permutation;
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110 | var sol2 = rightSolution.Variables[SolutionVariableName].Value as Permutation;
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111 |
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112 | return CalculateSimilarity(sol1, sol2);
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113 | }
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114 | }
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115 | }
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