[6056] | 1 | #region License Information
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| 2 | /* HeuristicLab
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[14185] | 3 | * Copyright (C) 2002-2016 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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[6056] | 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 System.Collections.Generic;
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[6507] | 24 | using System.Linq;
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| 25 | using System.Text;
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[6056] | 26 | using HeuristicLab.PluginInfrastructure;
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| 27 |
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| 28 | namespace HeuristicLab.Encodings.PermutationEncoding {
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| 29 | [NonDiscoverableType]
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[6507] | 30 | public class PermutationEqualityComparer : EqualityComparer<Permutation> {
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| 31 | public override bool Equals(Permutation x, Permutation y) {
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[15067] | 32 | if (x == null && y == null) return true;
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| 33 | if (x == null || y == null) return false;
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| 34 | if (ReferenceEquals(x, y)) return true;
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| 35 | if (x.Length != y.Length) return false;
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[6056] | 36 | if (x.PermutationType != y.PermutationType) return false;
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| 37 | switch (x.PermutationType) {
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| 38 | case PermutationTypes.Absolute:
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| 39 | return EqualsAbsolute(x, y);
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| 40 | case PermutationTypes.RelativeDirected:
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| 41 | return EqualsRelative(x, y, true);
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| 42 | case PermutationTypes.RelativeUndirected:
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| 43 | return EqualsRelative(x, y, false);
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| 44 | default:
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| 45 | throw new InvalidOperationException("unknown permutation type");
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| 46 | }
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| 47 | }
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| 48 |
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| 49 | private bool EqualsAbsolute(Permutation x, Permutation y) {
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[6507] | 50 | return x.SequenceEqual(y);
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[6056] | 51 | }
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| 52 |
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| 53 | private bool EqualsRelative(Permutation x, Permutation y, bool directed) {
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| 54 | int[] edgesX = CalculateEdgesVector(x);
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| 55 | int[] edgesY = CalculateEdgesVector(y);
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| 56 | for (int i = 0; i < x.Length; i++)
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| 57 | if ((edgesX[i] != edgesY[i]) && (directed || edgesX[edgesY[i]] != i))
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| 58 | return false;
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| 59 | return true;
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| 60 | }
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| 61 |
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| 62 | private int[] CalculateEdgesVector(Permutation permutation) {
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| 63 | // transform path representation into adjacency representation
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| 64 | int[] edgesVector = new int[permutation.Length];
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| 65 | for (int i = 0; i < permutation.Length - 1; i++)
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| 66 | edgesVector[permutation[i]] = permutation[i + 1];
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| 67 | edgesVector[permutation[permutation.Length - 1]] = permutation[0];
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| 68 | return edgesVector;
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| 69 | }
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| 70 |
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[6507] | 71 | public override int GetHashCode(Permutation obj) {
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[15067] | 72 | if (obj == null) throw new ArgumentNullException("obj", "PermutationEqualityComparer: Cannot compute hash value of null.");
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[6507] | 73 | return GenerateHashString(obj).GetHashCode();
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[6056] | 74 | }
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[6507] | 75 |
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| 76 | private string GenerateHashString(Permutation p) {
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| 77 | StringBuilder sb = new StringBuilder();
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| 78 | if (p.PermutationType == PermutationTypes.Absolute) {
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| 79 | for (int i = 0; i < p.Length; i++)
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| 80 | sb.Append(p[i].ToString() + ";");
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| 81 | } else {
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| 82 | int i = 0;
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| 83 | while (p[i] != 0) i++; // always start at element 0
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| 84 | if (p.PermutationType == PermutationTypes.RelativeDirected) {
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| 85 | for (int j = 0; j < p.Length; j++)
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| 86 | sb.Append(p.GetCircular(i + j).ToString() + ";");
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| 87 | } else {
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| 88 | 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
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| 89 | for (int j = 0; j < p.Length; j++) {
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| 90 | if (goLeft) sb.Append(p.GetCircular(i - j).ToString() + ";");
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| 91 | else sb.Append(p.GetCircular(i + j).ToString() + ";");
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| 92 | }
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| 93 | }
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| 94 | }
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| 95 | return sb.ToString();
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| 96 | }
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[6056] | 97 | }
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| 98 | }
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