#region License Information /* HeuristicLab * Copyright (C) 2002-2016 Heuristic and Evolutionary Algorithms Laboratory (HEAL) * * This file is part of HeuristicLab. * * HeuristicLab is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * HeuristicLab is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with HeuristicLab. If not, see . */ #endregion using System; using System.Collections.Generic; using System.Linq; using System.Text; using HeuristicLab.PluginInfrastructure; namespace HeuristicLab.Encodings.PermutationEncoding { [NonDiscoverableType] public class PermutationEqualityComparer : EqualityComparer { public override bool Equals(Permutation x, Permutation y) { if (x == null && y == null) return true; if (x == null || y == null) return false; if (ReferenceEquals(x, y)) return true; if (x.Length != y.Length) return false; if (x.PermutationType != y.PermutationType) return false; switch (x.PermutationType) { case PermutationTypes.Absolute: return EqualsAbsolute(x, y); case PermutationTypes.RelativeDirected: return EqualsRelative(x, y, true); case PermutationTypes.RelativeUndirected: return EqualsRelative(x, y, false); default: throw new InvalidOperationException("unknown permutation type"); } } private bool EqualsAbsolute(Permutation x, Permutation y) { return x.SequenceEqual(y); } private bool EqualsRelative(Permutation x, Permutation y, bool directed) { int[] edgesX = CalculateEdgesVector(x); int[] edgesY = CalculateEdgesVector(y); for (int i = 0; i < x.Length; i++) if ((edgesX[i] != edgesY[i]) && (directed || edgesX[edgesY[i]] != i)) return false; return true; } private int[] CalculateEdgesVector(Permutation permutation) { // transform path representation into adjacency representation int[] edgesVector = new int[permutation.Length]; for (int i = 0; i < permutation.Length - 1; i++) edgesVector[permutation[i]] = permutation[i + 1]; edgesVector[permutation[permutation.Length - 1]] = permutation[0]; return edgesVector; } public override int GetHashCode(Permutation obj) { if (obj == null) throw new ArgumentNullException("obj", "PermutationEqualityComparer: Cannot compute hash value of null."); return GenerateHashString(obj).GetHashCode(); } private string GenerateHashString(Permutation p) { StringBuilder sb = new StringBuilder(); if (p.PermutationType == PermutationTypes.Absolute) { for (int i = 0; i < p.Length; i++) sb.Append(p[i].ToString() + ";"); } else { int i = 0; while (p[i] != 0) i++; // always start at element 0 if (p.PermutationType == PermutationTypes.RelativeDirected) { for (int j = 0; j < p.Length; j++) sb.Append(p.GetCircular(i + j).ToString() + ";"); } else { 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 for (int j = 0; j < p.Length; j++) { if (goLeft) sb.Append(p.GetCircular(i - j).ToString() + ";"); else sb.Append(p.GetCircular(i + j).ToString() + ";"); } } } return sb.ToString(); } } }