1 | #region License Information
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2 | /* HeuristicLab
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3 | * Copyright (C) 2002-2015 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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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 HeuristicLab.Common;
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24 | using HeuristicLab.Core;
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25 | using HeuristicLab.Data;
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26 | using HeuristicLab.Encodings.PermutationEncoding;
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27 | using HeuristicLab.Parameters;
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28 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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29 |
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30 | namespace HeuristicLab.Problems.QuadraticAssignment {
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31 | [Item("QAPSwap2MoveEvaluator", "Evaluated a swap-2 move on a QAP solution.")]
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32 | [StorableType("1A185197-0F5F-4892-8F24-F599E2F533AA")]
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33 | public class QAPSwap2MoveEvaluator : QAPMoveEvaluator, IPermutationSwap2MoveOperator {
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34 | public ILookupParameter<Swap2Move> Swap2MoveParameter {
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35 | get { return (ILookupParameter<Swap2Move>)Parameters["Swap2Move"]; }
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36 | }
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37 |
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38 | [StorableConstructor]
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39 | protected QAPSwap2MoveEvaluator(bool deserializing) : base(deserializing) { }
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40 | protected QAPSwap2MoveEvaluator(QAPSwap2MoveEvaluator original, Cloner cloner)
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41 | : base(original, cloner) {
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42 | }
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43 | public QAPSwap2MoveEvaluator() {
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44 | Parameters.Add(new LookupParameter<Swap2Move>("Swap2Move", "The move to evaluate."));
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45 | }
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46 |
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47 | public override IDeepCloneable Clone(Cloner cloner) {
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48 | return new QAPSwap2MoveEvaluator(this, cloner);
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49 | }
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50 |
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51 | /// <summary>
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52 | /// Calculates the quality of the move <paramref name="move"/> by evaluating the changes.
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53 | /// The runtime complexity of this method is O(N) with N being the size of the permutation.
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54 | /// </summary>
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55 | /// <param name="assignment">The current permutation.</param>
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56 | /// <param name="move">The move that is to be evaluated if it was applied to the current permutation.</param>
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57 | /// <param name="weights">The weights matrix.</param>
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58 | /// <param name="distances">The distances matrix.</param>
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59 | /// <returns>The relative change in quality if <paramref name="move"/> was applied to <paramref name="assignment"/>.</returns>
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60 | public static double Apply(Permutation assignment, Swap2Move move, DoubleMatrix weights, DoubleMatrix distances) {
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61 | if (move.Index1 == move.Index2) return 0;
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62 | double moveQuality = 0;
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63 | int fac1 = move.Index1, fac2 = move.Index2;
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64 | int loc1 = assignment[fac1], loc2 = assignment[fac2];
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65 |
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66 | for (int j = 0; j < assignment.Length; j++) {
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67 | if (j == fac1) {
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68 | moveQuality += weights[fac1, fac1] * (distances[loc2, loc2] - distances[loc1, loc1]);
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69 | moveQuality += weights[fac1, fac2] * (distances[loc2, loc1] - distances[loc1, loc2]);
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70 | } else if (j == fac2) {
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71 | moveQuality += weights[fac2, fac2] * (distances[loc1, loc1] - distances[loc2, loc2]);
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72 | moveQuality += weights[fac2, fac1] * (distances[loc1, loc2] - distances[loc2, loc1]);
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73 | } else {
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74 | int locJ = assignment[j];
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75 | moveQuality += weights[fac1, j] * (distances[loc2, locJ] - distances[loc1, locJ]);
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76 | moveQuality += weights[j, fac1] * (distances[locJ, loc2] - distances[locJ, loc1]);
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77 | moveQuality += weights[fac2, j] * (distances[loc1, locJ] - distances[loc2, locJ]);
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78 | moveQuality += weights[j, fac2] * (distances[locJ, loc1] - distances[locJ, loc2]);
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79 | }
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80 | }
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81 | return moveQuality;
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82 | }
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83 |
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84 | /// <summary>
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85 | /// Is able to compute the move qualities faster O(1) in some cases if it knows the quality of
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86 | /// performing the move <paramref name="move"/> previously. In other cases it performs a
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87 | /// standard move quality calculation with runtime complexity O(N).
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88 | /// </summary>
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89 | /// <remarks>
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90 | /// The number of cases that the calculation can be performed faster grows with N^2
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91 | /// while the number of cases which require a larger recalculation grows linearly with N.
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92 | /// Larger problem instances thus benefit from this faster method to a larger degree.
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93 | /// </remarks>
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94 | /// <param name="assignment">The current permutation.</param>
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95 | /// <param name="move">The current move that is to be evaluated.</param>
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96 | /// <param name="previousQuality">The quality of that move as evaluated for the previous permutation.</param>
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97 | /// <param name="weights">The weigths matrix.</param>
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98 | /// <param name="distances">The distances matrix.</param>
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99 | /// <param name="lastMove">The move that was applied to transform the permutation from the previous to the current one.</param>
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100 | /// <returns>The relative change in quality if <paramref name="move"/> was applied to <paramref name="assignment"/>.</returns>
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101 | public static double Apply(Permutation assignment, Swap2Move move, double previousQuality,
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102 | DoubleMatrix weights, DoubleMatrix distances, Swap2Move lastMove) {
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103 | bool overlapsLastMove = move.Index1 == lastMove.Index1
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104 | || move.Index2 == lastMove.Index1
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105 | || move.Index1 == lastMove.Index2
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106 | || move.Index2 == lastMove.Index2;
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107 |
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108 | if (!overlapsLastMove) {
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109 | int r = lastMove.Index1, u = move.Index1, s = lastMove.Index2, v = move.Index2;
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110 | int pR = assignment[lastMove.Index1], pU = assignment[move.Index1], pS = assignment[lastMove.Index2], pV = assignment[move.Index2];
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111 |
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112 | return previousQuality
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113 | + (weights[r, u] - weights[r, v] + weights[s, v] - weights[s, u])
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114 | * (distances[pS, pU] - distances[pS, pV] + distances[pR, pV] - distances[pR, pU])
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115 | + (weights[u, r] - weights[v, r] + weights[v, s] - weights[u, s])
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116 | * (distances[pU, pS] - distances[pV, pS] + distances[pV, pR] - distances[pU, pR]);
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117 | } else {
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118 | return Apply(assignment, move, weights, distances);
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119 | }
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120 | }
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121 |
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122 | public override IOperation Apply() {
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123 | Swap2Move move = Swap2MoveParameter.ActualValue;
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124 | if (move == null) throw new InvalidOperationException("Swap-2 move is not found.");
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125 | Permutation assignment = PermutationParameter.ActualValue;
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126 | DoubleMatrix distances = DistancesParameter.ActualValue;
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127 | DoubleMatrix weights = WeightsParameter.ActualValue;
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128 |
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129 | double moveQuality = QualityParameter.ActualValue.Value;
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130 | moveQuality += Apply(assignment, move, weights, distances);
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131 | MoveQualityParameter.ActualValue = new DoubleValue(moveQuality);
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132 | return base.Apply();
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133 | }
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134 | }
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135 | }
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