1 | #region License Information
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2 | /* HeuristicLab
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3 | * Copyright (C) 2002-2017 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 System.Linq;
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24 | using System.Threading;
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25 | using HeuristicLab.Common;
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26 | using HeuristicLab.Core;
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27 | using HeuristicLab.Data;
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28 | using HeuristicLab.Encodings.IntegerVectorEncoding;
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29 | using HeuristicLab.Optimization;
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30 | using HeuristicLab.Parameters;
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31 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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32 |
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33 | namespace HeuristicLab.Problems.GeneralizedQuadraticAssignment.Algorithms.GRASP {
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34 |
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35 | /// <summary>
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36 | /// This is an implementation of the algorithm described in Mateus, G.R., Resende, M.G.C. & Silva, R.M.A. J Heuristics (2011) 17: 527. https://doi.org/10.1007/s10732-010-9144-0
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37 | /// </summary>
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38 | [Item("GRASP+PR (GQAP)", "The algorithm implements the Greedy Randomized Adaptive Search Procedure (GRASP) with Path Relinking as described in Mateus, G., Resende, M., and Silva, R. 2011. GRASP with path-relinking for the generalized quadratic assignment problem. Journal of Heuristics 17, Springer Netherlands, pp. 527-565.")]
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39 | [Creatable(CreatableAttribute.Categories.PopulationBasedAlgorithms)]
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40 | [StorableClass]
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41 | public sealed class GRASP : StochasticAlgorithm<GRASPContext> {
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42 |
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43 | public override bool SupportsPause {
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44 | get { return true; }
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45 | }
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46 |
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47 | public override Type ProblemType {
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48 | get { return typeof(GQAP); }
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49 | }
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50 |
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51 | public new GQAP Problem {
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52 | get { return (GQAP)base.Problem; }
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53 | set { base.Problem = value; }
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54 | }
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55 |
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56 | [Storable]
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57 | private FixedValueParameter<IntValue> eliteSetSizeParameter;
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58 | private IFixedValueParameter<IntValue> EliteSetSizeParameter {
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59 | get { return eliteSetSizeParameter; }
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60 | }
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61 | [Storable]
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62 | private FixedValueParameter<IntValue> minimiumEliteSetSizeParameter;
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63 | public IFixedValueParameter<IntValue> MinimumEliteSetSizeParameter {
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64 | get { return minimiumEliteSetSizeParameter; }
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65 | }
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66 | [Storable]
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67 | private FixedValueParameter<IntValue> maximumLocalSearchIterationsParameter;
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68 | public IFixedValueParameter<IntValue> MaximumLocalSearchIterationsParameter {
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69 | get { return maximumLocalSearchIterationsParameter; }
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70 | }
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71 | [Storable]
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72 | private FixedValueParameter<PercentValue> candidateSizeFactorParameter;
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73 | public IFixedValueParameter<PercentValue> CandidateSizeFactorParameter {
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74 | get { return candidateSizeFactorParameter; }
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75 | }
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76 | [Storable]
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77 | private FixedValueParameter<IntValue> maximumCandidateListSizeParameter;
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78 | public IFixedValueParameter<IntValue> MaximumCandidateListSizeParameter {
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79 | get { return maximumCandidateListSizeParameter; }
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80 | }
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81 | [Storable]
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82 | private FixedValueParameter<PercentValue> oneMoveProbabilityParameter;
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83 | public IFixedValueParameter<PercentValue> OneMoveProbabilityParameter {
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84 | get { return oneMoveProbabilityParameter; }
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85 | }
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86 | [Storable]
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87 | private FixedValueParameter<IntValue> minimumDifferenceParameter;
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88 | public IFixedValueParameter<IntValue> MinimumDifferenceParameter {
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89 | get { return minimumDifferenceParameter; }
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90 | }
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91 |
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92 | public int EliteSetSize {
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93 | get { return eliteSetSizeParameter.Value.Value; }
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94 | set { eliteSetSizeParameter.Value.Value = value; }
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95 | }
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96 | public int MinimumEliteSetSize {
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97 | get { return minimiumEliteSetSizeParameter.Value.Value; }
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98 | set { minimiumEliteSetSizeParameter.Value.Value = value; }
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99 | }
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100 | public int MaximumLocalSearchIterations {
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101 | get { return maximumLocalSearchIterationsParameter.Value.Value; }
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102 | set { maximumLocalSearchIterationsParameter.Value.Value = value; }
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103 | }
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104 | public double CandidateSizeFactor {
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105 | get { return candidateSizeFactorParameter.Value.Value; }
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106 | set { candidateSizeFactorParameter.Value.Value = value; }
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107 | }
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108 | public int MaximumCandidateListSize {
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109 | get { return maximumCandidateListSizeParameter.Value.Value; }
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110 | set { maximumCandidateListSizeParameter.Value.Value = value; }
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111 | }
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112 | public double OneMoveProbability {
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113 | get { return oneMoveProbabilityParameter.Value.Value; }
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114 | set { oneMoveProbabilityParameter.Value.Value = value; }
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115 | }
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116 | public int MinimumDifference {
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117 | get { return minimumDifferenceParameter.Value.Value; }
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118 | set { minimumDifferenceParameter.Value.Value = value; }
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119 | }
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120 |
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121 | [StorableConstructor]
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122 | private GRASP(bool deserializing) : base(deserializing) { }
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123 | private GRASP(GRASP original, Cloner cloner)
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124 | : base(original, cloner) {
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125 | eliteSetSizeParameter = cloner.Clone(original.eliteSetSizeParameter);
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126 | minimiumEliteSetSizeParameter = cloner.Clone(original.minimiumEliteSetSizeParameter);
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127 | maximumLocalSearchIterationsParameter = cloner.Clone(original.maximumLocalSearchIterationsParameter);
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128 | candidateSizeFactorParameter = cloner.Clone(original.candidateSizeFactorParameter);
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129 | maximumCandidateListSizeParameter = cloner.Clone(original.maximumCandidateListSizeParameter);
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130 | oneMoveProbabilityParameter = cloner.Clone(original.oneMoveProbabilityParameter);
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131 | minimumDifferenceParameter = cloner.Clone(original.minimumDifferenceParameter);
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132 | }
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133 | public GRASP() {
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134 | Parameters.Add(eliteSetSizeParameter = new FixedValueParameter<IntValue>("EliteSetSize", "The (maximum) size of the elite set.", new IntValue(10)));
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135 | Parameters.Add(minimiumEliteSetSizeParameter = new FixedValueParameter<IntValue>("MinimumEliteSetSize", "(ρ) The minimal size of the elite set, before local search and path relinking are applied.", new IntValue(2)));
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136 | Parameters.Add(maximumLocalSearchIterationsParameter = new FixedValueParameter<IntValue>("MaximumLocalSearchIteration", "The maximum number of iterations that the approximate local search should run", new IntValue(100)));
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137 | Parameters.Add(candidateSizeFactorParameter = new FixedValueParameter<PercentValue>("CandidateSizeFactor", "(η) Determines the size of the set of feasible moves in each path - relinking step relative to the maximum size.A value of 50 % means that only half of all possible moves are considered each step.", new PercentValue(0.5)));
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138 | Parameters.Add(maximumCandidateListSizeParameter = new FixedValueParameter<IntValue>("MaximumCandidateListSize", "The maximum number of candidates that should be found in each step.", new IntValue(10)));
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139 | Parameters.Add(oneMoveProbabilityParameter = new FixedValueParameter<PercentValue>("OneMoveProbability", "The probability for performing a 1-move, which is the opposite of performing a 2-move.", new PercentValue(.5)));
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140 | Parameters.Add(minimumDifferenceParameter = new FixedValueParameter<IntValue>("MinimumDifference", "The minimum amount of difference between two solutions so that they are both accepted in the elite set.", new IntValue(4)));
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141 |
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142 | Problem = new GQAP();
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143 | }
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144 |
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145 | public override IDeepCloneable Clone(Cloner cloner) {
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146 | return new GRASP(this, cloner);
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147 | }
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148 |
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149 | protected override void Initialize(CancellationToken cancellationToken) {
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150 | base.Initialize(cancellationToken);
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151 |
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152 | Context.Problem = Problem;
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153 | Context.BestQuality = double.NaN;
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154 | Context.BestSolution = null;
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155 |
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156 | Results.Add(new Result("Iterations", new IntValue(Context.Iterations)));
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157 | Results.Add(new Result("EvaluatedSolutions", new IntValue(Context.EvaluatedSolutions)));
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158 | Results.Add(new Result("BestQuality", new DoubleValue(Context.BestQuality)));
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159 | Results.Add(new Result("BestSolution", typeof(GQAPSolution)));
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160 |
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161 | Context.RunOperator(Analyzer, Context.Scope, cancellationToken);
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162 | }
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163 |
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164 | protected override void Run(CancellationToken cancellationToken) {
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165 | var eq = new IntegerVectorEqualityComparer();
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166 | while (!StoppingCriterion()) { // line 2 in Algorithm 1
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167 | // next: line 3 in Algorithm 1
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168 | var pi_prime_vec = GreedyRandomizedSolutionCreator.CreateSolution(Context.Random, Problem.ProblemInstance, 1000, false, cancellationToken);
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169 | if (Context.PopulationCount >= MinimumEliteSetSize) { // line 4 in Algorithm 1
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170 | GQAPSolution pi_prime;
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171 | if (!Problem.ProblemInstance.IsFeasible(pi_prime_vec)) // line 5 in Algorithm 1
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172 | pi_prime = Context.AtPopulation(Context.Random.Next(Context.PopulationCount)).Solution; // line 6 in Algorithm 1
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173 | else {
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174 | // This is necessary, because pi_prime has not been evaluated yet and such details are not covered in Algorithm 1
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175 | pi_prime = Problem.ProblemInstance.ToEvaluatedSolution(pi_prime_vec);
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176 | Context.EvaluatedSolutions++;
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177 | }
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178 |
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179 | ApproxLocalSearch(pi_prime); // line 8 in Algorithm 1
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180 | var pi_plus = Context.AtPopulation(Context.Random.Next(Context.PopulationCount)); // line 9 in Algorithm 1
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181 | pi_prime = PathRelinking(pi_prime, pi_plus.Solution); // line 10 in Algorithm 1
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182 | ApproxLocalSearch(pi_prime); // line 11 in Algorithm 1
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183 | var fitness = Problem.ProblemInstance.ToSingleObjective(pi_prime.Evaluation);
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184 | // Book-keeping
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185 | if (Context.BestQuality > fitness) {
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186 | Context.BestQuality = fitness;
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187 | Context.BestSolution = (GQAPSolution)pi_prime.Clone();
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188 | }
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189 |
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190 | if (Context.PopulationCount == EliteSetSize) { // line 12 in Algorithm 1
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191 | var fit = Problem.ProblemInstance.ToSingleObjective(pi_prime.Evaluation);
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192 | double[] similarities = Context.Population.Select(x => HammingSimilarityCalculator.CalculateSimilarity(x.Solution.Assignment, pi_prime.Assignment)).ToArray();
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193 | if (similarities.Max() <= 1.0 - (MinimumDifference / (double)pi_prime.Assignment.Length)) { // cond. 2 of line 13 in Algorithm 1
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194 | var replacement = Context.Population.Select((v, i) => new { V = v, Index = i })
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195 | .Where(x => x.V.Fitness >= fit).ToArray();
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196 | if (replacement.Length > 0) { // cond. 1 of line 13 in Algorithm 1
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197 | // next two lines: line 14 in Algorithm 1
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198 | replacement = replacement.OrderBy(x => similarities[x.Index]).ToArray();
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199 | Context.ReplaceAtPopulation(replacement.Last().Index, Context.ToScope(pi_prime, fit));
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200 | }
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201 | }
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202 | } else if (IsSufficientlyDifferent(pi_prime.Assignment)) { // line 17 in Algorithm 1
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203 | Context.AddToPopulation(Context.ToScope(pi_prime, Problem.ProblemInstance.ToSingleObjective(pi_prime.Evaluation))); // line 18 in Algorithm 1
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204 | }
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205 | } else if (Problem.ProblemInstance.IsFeasible(pi_prime_vec) /* cond. 1 of line 21 in Algorithm 1 */
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206 | && IsSufficientlyDifferent(pi_prime_vec)) /* cond. 2 of line 21 in Algorithm 1 */ {
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207 | var pi_prime = Problem.ProblemInstance.ToEvaluatedSolution(pi_prime_vec);
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208 | Context.EvaluatedSolutions++;
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209 | var fitness = Problem.ProblemInstance.ToSingleObjective(pi_prime.Evaluation);
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210 | Context.AddToPopulation(Context.ToScope(pi_prime, fitness)); /* line 22 in Algorithm 1 */
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211 | // Book-keeping
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212 | if (Context.PopulationCount == 1 || Context.BestQuality > fitness) {
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213 | Context.BestQuality = fitness;
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214 | Context.BestSolution = (GQAPSolution)pi_prime.Clone();
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215 | }
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216 | }
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217 |
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218 | IResult result;
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219 | if (Results.TryGetValue("Iterations", out result))
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220 | ((IntValue)result.Value).Value = Context.Iterations;
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221 | else Results.Add(new Result("Iterations", new IntValue(Context.Iterations)));
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222 | if (Results.TryGetValue("EvaluatedSolutions", out result))
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223 | ((IntValue)result.Value).Value = Context.EvaluatedSolutions;
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224 | else Results.Add(new Result("EvaluatedSolutions", new IntValue(Context.EvaluatedSolutions)));
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225 | if (Results.TryGetValue("BestQuality", out result))
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226 | ((DoubleValue)result.Value).Value = Context.BestQuality;
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227 | else Results.Add(new Result("BestQuality", new DoubleValue(Context.BestQuality)));
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228 | if (Results.TryGetValue("BestSolution", out result))
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229 | result.Value = Context.BestSolution;
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230 | else Results.Add(new Result("BestSolution", Context.BestSolution));
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231 |
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232 | Context.RunOperator(Analyzer, Context.Scope, cancellationToken);
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233 |
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234 | Context.Iterations++;
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235 | if (cancellationToken.IsCancellationRequested) break;
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236 | }
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237 | }
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238 |
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239 | private bool IsSufficientlyDifferent(IntegerVector vec) {
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240 | return Context.Population.All(x =>
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241 | HammingSimilarityCalculator.CalculateSimilarity(vec, x.Solution.Assignment) <= 1.0 - (MinimumDifference / (double)vec.Length)
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242 | );
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243 | }
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244 |
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245 | private GQAPSolution PathRelinking(GQAPSolution pi_prime, GQAPSolution pi_plus) {
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246 | // Following code represents line 1 of Algorithm 4
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247 | IntegerVector source = pi_prime.Assignment, target = pi_plus.Assignment;
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248 | Evaluation sourceEval = pi_prime.Evaluation, targetEval = pi_plus.Evaluation;
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249 | var sourceFit = Problem.ProblemInstance.ToSingleObjective(sourceEval);
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250 | var targetFit = Problem.ProblemInstance.ToSingleObjective(targetEval);
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251 | if (targetFit < sourceFit) {
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252 | var h = source;
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253 | source = target;
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254 | target = h;
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255 | var hh = sourceEval;
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256 | sourceEval = targetEval;
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257 | targetEval = hh;
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258 | }
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259 | int evaluatedSolutions;
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260 | // lines 2-36 of Algorithm 4 are implemented in the following call
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261 | var pi_star = GQAPPathRelinking.Apply(Context.Random, source, sourceEval,
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262 | target, targetEval, Problem.ProblemInstance, CandidateSizeFactor,
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263 | out evaluatedSolutions);
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264 | Context.EvaluatedSolutions += evaluatedSolutions;
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265 | return pi_star;
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266 | }
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267 |
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268 | private void ApproxLocalSearch(GQAPSolution pi_prime) {
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269 | var localSearchEvaluations = 0;
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270 | ApproximateLocalSearch.Apply(Context.Random, pi_prime, MaximumCandidateListSize,
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271 | OneMoveProbability, MaximumLocalSearchIterations, Problem.ProblemInstance, out localSearchEvaluations);
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272 | Context.EvaluatedSolutions += localSearchEvaluations;
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273 | }
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274 | }
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275 | }
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