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source: trunk/sources/HeuristicLab.Problems.TravelingSalesman/3.3/SimilarityCalculators/TSPSimilarityCalculator.cs @ 9030

Last change on this file since 9030 was 9030, checked in by ascheibe, 10 years ago

#1331 improved TSPSimilarityCalculator and SingleObjectiveSolutionSimilarityCalculator

File size: 4.7 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2012 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    private TSPSimilarityCalculator(bool deserializing) : base(deserializing) { }
38    private TSPSimilarityCalculator(TSPSimilarityCalculator original, Cloner cloner) : base(original, cloner) { }
39    public TSPSimilarityCalculator() : base() { }
40
41    public override IDeepCloneable Clone(Cloner cloner) {
42      return new TSPSimilarityCalculator(this, cloner);
43    }
44
45    public static double CalculateSimilarity(Permutation left, Permutation right) {
46      if (left == null || right == null)
47        throw new ArgumentException("Cannot calculate similarity because one of the provided solutions or both are null.");
48      if (left.PermutationType != right.PermutationType)
49        throw new ArgumentException("Cannot calculate similarity because the provided solutions have different types.");
50      if (left.Length != right.Length)
51        throw new ArgumentException("Cannot calculate similarity because the provided solutions have different lengths.");
52      if (object.ReferenceEquals(left, right)) return 1.0;
53
54      switch (left.PermutationType) {
55        case PermutationTypes.Absolute:
56          return CalculateAbsolute(left, right);
57        case PermutationTypes.RelativeDirected:
58          return CalculateRelativeDirected(left, right);
59        case PermutationTypes.RelativeUndirected:
60          return CalculateRelativeUndirected(left, right);
61        default:
62          throw new InvalidOperationException("unknown permutation type");
63      }
64    }
65
66    private static double CalculateAbsolute(Permutation left, Permutation right) {
67      double similarity = 0.0;
68      for (int i = 0; i < left.Length; i++)
69        if (left[i] == right[i]) similarity++;
70
71      return similarity / left.Length;
72    }
73
74    private static double CalculateRelativeDirected(Permutation left, Permutation right) {
75      int[] edges = new int[right.Length];
76      for (int i = 0; i < right.Length; i++)
77        edges[right[i]] = right[(i + 1) % right.Length];
78
79      double similarity = 0.0;
80      for (int i = 0; i < left.Length; i++)
81        if (left[(i + 1) % left.Length] == edges[left[i]]) similarity++;
82
83      return similarity / left.Length;
84    }
85
86    private static double CalculateRelativeUndirected(Permutation left, Permutation right) {
87      int[,] edges = new int[right.Length, 2];
88      for (int i = 0; i < right.Length; i++) {
89        edges[right[i], 0] = right[(i + 1) % right.Length];
90        edges[right[i], 1] = right[(i - 1 + right.Length) % right.Length];
91      }
92
93      double similarity = 0.0;
94      for (int i = 0; i < left.Length; i++) {
95        int targetCity = left[(i + 1) % left.Length];
96        if (targetCity == edges[left[i], 0] || targetCity == edges[left[i], 1])
97          similarity++;
98      }
99
100      return similarity / left.Length;
101    }
102
103    public override double CalculateSolutionSimilarity(IScope leftSolution, IScope rightSolution) {
104      var sol1 = leftSolution.Variables[SolutionVariableName].Value as Permutation;
105      var sol2 = rightSolution.Variables[SolutionVariableName].Value as Permutation;
106
107      return CalculateSimilarity(sol1, sol2);
108    }
109  }
110}
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