source: branches/2520_PersistenceReintegration/HeuristicLab.Encodings.PermutationEncoding/3.3/PermutationEqualityComparer.cs @ 16474

Last change on this file since 16474 was 16474, checked in by gkronber, 9 months ago

#2520: checked and added StorableType attribute in projects up to HeuristicLab.MainForm

File size: 3.9 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2019 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 System.Collections.Generic;
24using System.Linq;
25using System.Text;
26using HeuristicLab.PluginInfrastructure;
27using HEAL.Fossil;
28
29namespace HeuristicLab.Encodings.PermutationEncoding {
30  [NonDiscoverableType]
31  [StorableType("9e0bdbda-0d76-4032-bc69-f5acbbfd5d37")]
32  public class PermutationEqualityComparer : EqualityComparer<Permutation> {
33    public override bool Equals(Permutation x, Permutation y) {
34      if (ReferenceEquals(x, y)) return true;
35      if (x == null || y == null) return false;
36      if (x.Length != y.Length) return false;
37      if (x.PermutationType != y.PermutationType) return false;
38      switch (x.PermutationType) {
39        case PermutationTypes.Absolute:
40          return EqualsAbsolute(x, y);
41        case PermutationTypes.RelativeDirected:
42          return EqualsRelative(x, y, true);
43        case PermutationTypes.RelativeUndirected:
44          return EqualsRelative(x, y, false);
45        default:
46          throw new InvalidOperationException("unknown permutation type");
47      }
48    }
49
50    private bool EqualsAbsolute(Permutation x, Permutation y) {
51      return x.SequenceEqual(y);
52    }
53
54    private bool EqualsRelative(Permutation x, Permutation y, bool directed) {
55      int[] edgesX = CalculateEdgesVector(x);
56      int[] edgesY = CalculateEdgesVector(y);
57      for (int i = 0; i < x.Length; i++)
58        if ((edgesX[i] != edgesY[i]) && (directed || edgesX[edgesY[i]] != i))
59          return false;
60      return true;
61    }
62
63    private int[] CalculateEdgesVector(Permutation permutation) {
64      // transform path representation into adjacency representation
65      int[] edgesVector = new int[permutation.Length];
66      for (int i = 0; i < permutation.Length - 1; i++)
67        edgesVector[permutation[i]] = permutation[i + 1];
68      edgesVector[permutation[permutation.Length - 1]] = permutation[0];
69      return edgesVector;
70    }
71
72    public override int GetHashCode(Permutation obj) {
73      if (obj == null) throw new ArgumentNullException("obj", "PermutationEqualityComparer: Cannot compute hash value of null.");
74      return GenerateHashString(obj).GetHashCode();
75    }
76
77    private string GenerateHashString(Permutation p) {
78      StringBuilder sb = new StringBuilder();
79      if (p.PermutationType == PermutationTypes.Absolute) {
80        for (int i = 0; i < p.Length; i++)
81          sb.Append(p[i].ToString() + ";");
82      } else {
83        int i = 0;
84        while (p[i] != 0) i++; // always start at element 0
85        if (p.PermutationType == PermutationTypes.RelativeDirected) {
86          for (int j = 0; j < p.Length; j++)
87            sb.Append(p.GetCircular(i + j).ToString() + ";");
88        } else {
89          bool goLeft = p.GetCircular(i - 1) < p.GetCircular(i + 1); // go in direction of the lowest edge so that the total inversion and its original return the same hash code
90          for (int j = 0; j < p.Length; j++) {
91            if (goLeft) sb.Append(p.GetCircular(i - j).ToString() + ";");
92            else sb.Append(p.GetCircular(i + j).ToString() + ";");
93          }
94        }
95      }
96      return sb.ToString();
97    }
98  }
99}
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