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source: trunk/sources/HeuristicLab.Problems.TravelingSalesman/3.3/SimilarityCalculators/TSPSimilarityCalculator.cs @ 12070

Last change on this file since 12070 was 12070, checked in by jkarder, 9 years ago

#2332: added SolutionSimilarityCalculator.IsCommutative

File size: 5.0 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2015 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;
23using HeuristicLab.Common;
24using HeuristicLab.Core;
25using HeuristicLab.Encodings.PermutationEncoding;
26using HeuristicLab.Optimization.Operators;
27
28namespace HeuristicLab.Problems.TravelingSalesman {
29  /// <summary>
30  /// An operator that performs similarity calculation between two traveling salesman solutions.
31  /// </summary>
32  /// <remarks>
33  /// The operator calculates the similarity based on the number of edges the two solutions have in common.
34  /// </remarks>
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.")]
36  public sealed class TSPSimilarityCalculator : SingleObjectiveSolutionSimilarityCalculator {
37    protected override bool IsCommutative { get { return true; } }
38
39    private TSPSimilarityCalculator(bool deserializing) : base(deserializing) { }
40    private TSPSimilarityCalculator(TSPSimilarityCalculator original, Cloner cloner) : base(original, cloner) { }
41    public TSPSimilarityCalculator() : base() { }
42
43    public override IDeepCloneable Clone(Cloner cloner) {
44      return new TSPSimilarityCalculator(this, cloner);
45    }
46
47    public static double CalculateSimilarity(Permutation left, Permutation right) {
48      if (left == null || right == null)
49        throw new ArgumentException("Cannot calculate similarity because one of the provided solutions or both are null.");
50      if (left.PermutationType != right.PermutationType)
51        throw new ArgumentException("Cannot calculate similarity because the provided solutions have different types.");
52      if (left.Length != right.Length)
53        throw new ArgumentException("Cannot calculate similarity because the provided solutions have different lengths.");
54      if (object.ReferenceEquals(left, right)) return 1.0;
55
56      switch (left.PermutationType) {
57        case PermutationTypes.Absolute:
58          return CalculateAbsolute(left, right);
59        case PermutationTypes.RelativeDirected:
60          return CalculateRelativeDirected(left, right);
61        case PermutationTypes.RelativeUndirected:
62          return CalculateRelativeUndirected(left, right);
63        default:
64          throw new InvalidOperationException("unknown permutation type");
65      }
66    }
67
68    private static double CalculateAbsolute(Permutation left, Permutation right) {
69      double similarity = 0.0;
70      for (int i = 0; i < left.Length; i++)
71        if (left[i] == right[i]) similarity++;
72
73      return similarity / left.Length;
74    }
75
76    private static double CalculateRelativeDirected(Permutation left, Permutation right) {
77      int[] edgesR = CalculateEdgesVector(right);
78      int[] edgesL = CalculateEdgesVector(left);
79
80      double similarity = 0.0;
81      for (int i = 0; i < left.Length; i++) {
82        if (edgesL[i] == edgesR[i]) similarity++;
83      }
84
85      return similarity / left.Length;
86    }
87
88    private static double CalculateRelativeUndirected(Permutation left, Permutation right) {
89      int[] edgesR = CalculateEdgesVector(right);
90      int[] edgesL = CalculateEdgesVector(left);
91
92      double similarity = 0.0;
93      for (int i = 0; i < left.Length; i++) {
94        if ((edgesL[i] == edgesR[i]) || (edgesL[edgesR[i]] == i))
95          similarity++;
96      }
97
98      return similarity / left.Length;
99    }
100
101    private static int[] CalculateEdgesVector(Permutation permutation) {
102      // transform path representation into adjacency representation
103      int[] edgesVector = new int[permutation.Length];
104      for (int i = 0; i < permutation.Length - 1; i++)
105        edgesVector[permutation[i]] = permutation[i + 1];
106      edgesVector[permutation[permutation.Length - 1]] = permutation[0];
107      return edgesVector;
108    }
109
110    public override double CalculateSolutionSimilarity(IScope leftSolution, IScope rightSolution) {
111      var sol1 = leftSolution.Variables[SolutionVariableName].Value as Permutation;
112      var sol2 = rightSolution.Variables[SolutionVariableName].Value as Permutation;
113
114      return CalculateSimilarity(sol1, sol2);
115    }
116  }
117}
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