[13861] | 1 | #region License Information
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| 2 | /* HeuristicLab
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| 3 | * Copyright (C) 2002-2016 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 HeuristicLab.Common;
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| 23 | using HeuristicLab.Core;
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| 24 | using HeuristicLab.Data;
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| 25 | using HeuristicLab.Encodings.PermutationEncoding;
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| 26 | using HeuristicLab.Optimization;
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| 27 | using HeuristicLab.Parameters;
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| 28 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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| 29 | using HeuristicLab.Problems.QuadraticAssignment;
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| 30 | using HeuristicLab.Random;
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| 31 | using System;
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| 32 | using System.Collections.Generic;
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| 33 | using System.Linq;
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[14690] | 34 | using System.Threading;
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[13861] | 35 |
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[14678] | 36 | namespace HeuristicLab.Analysis.FitnessLandscape {
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[13861] | 37 | [Item("Directed Walk (QAP-specific)", "")]
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| 38 | [StorableClass]
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| 39 | public class QAPDirectedWalk : CharacteristicCalculator {
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| 40 |
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| 41 | public IFixedValueParameter<IntValue> PathsParameter {
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| 42 | get { return (IFixedValueParameter<IntValue>)Parameters["Paths"]; }
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| 43 | }
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| 44 |
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| 45 | public IFixedValueParameter<BoolValue> BestImprovementParameter {
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| 46 | get { return (IFixedValueParameter<BoolValue>)Parameters["BestImprovement"]; }
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| 47 | }
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| 48 |
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| 49 | public IValueParameter<IntValue> SeedParameter {
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| 50 | get { return (IValueParameter<IntValue>)Parameters["Seed"]; }
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| 51 | }
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| 52 |
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[14690] | 53 | public IFixedValueParameter<BoolValue> LocalOptimaParameter {
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| 54 | get { return (IFixedValueParameter<BoolValue>)Parameters["LocalOptima"]; }
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| 55 | }
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| 56 |
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[13861] | 57 | public int Paths {
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| 58 | get { return PathsParameter.Value.Value; }
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| 59 | set { PathsParameter.Value.Value = value; }
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| 60 | }
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| 61 |
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| 62 | public bool BestImprovement {
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| 63 | get { return BestImprovementParameter.Value.Value; }
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| 64 | set { BestImprovementParameter.Value.Value = value; }
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| 65 | }
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| 66 |
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| 67 | public int? Seed {
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| 68 | get { return SeedParameter.Value != null ? SeedParameter.Value.Value : (int?)null; }
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| 69 | set { SeedParameter.Value = value.HasValue ? new IntValue(value.Value) : null; }
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| 70 | }
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| 71 |
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[14690] | 72 | public bool LocalOptima {
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| 73 | get { return LocalOptimaParameter.Value.Value; }
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| 74 | set { LocalOptimaParameter.Value.Value = value; }
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| 75 | }
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| 76 |
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[13861] | 77 | [StorableConstructor]
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| 78 | private QAPDirectedWalk(bool deserializing) : base(deserializing) { }
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| 79 | private QAPDirectedWalk(QAPDirectedWalk original, Cloner cloner) : base(original, cloner) { }
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| 80 | public QAPDirectedWalk() {
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[14691] | 81 | characteristics.AddRange(new[] { "Swap2.Sharpness", "Swap2.Bumpiness", "Swap2.Flatness", /*"Swap2.Steadiness"*/ }
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[13861] | 82 | .Select(x => new StringValue(x)).ToList());
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| 83 | Parameters.Add(new FixedValueParameter<IntValue>("Paths", "The number of paths to explore (a path is a set of solutions that connect two randomly chosen solutions).", new IntValue(50)));
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| 84 | Parameters.Add(new FixedValueParameter<BoolValue>("BestImprovement", "Whether the best of all alternatives should be chosen for each step in the path or just the first improving (least degrading) move should be made.", new BoolValue(true)));
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| 85 | Parameters.Add(new OptionalValueParameter<IntValue>("Seed", "The seed for the random number generator."));
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[14690] | 86 | Parameters.Add(new FixedValueParameter<BoolValue>("LocalOptima", "Whether to perform walks between local optima.", new BoolValue(false)));
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[13861] | 87 | }
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| 88 |
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| 89 | public override IDeepCloneable Clone(Cloner cloner) {
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| 90 | return new QAPDirectedWalk(this, cloner);
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| 91 | }
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| 92 |
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| 93 | public override bool CanCalculate() {
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| 94 | return Problem is QuadraticAssignmentProblem;
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| 95 | }
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| 96 |
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| 97 | public override IEnumerable<IResult> Calculate() {
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[14429] | 98 | IRandom random = Seed.HasValue ? new MersenneTwister((uint)Seed.Value) : new MersenneTwister();
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| 99 | var qap = (QuadraticAssignmentProblem)Problem;
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[13861] | 100 | var pathCount = Paths;
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| 101 |
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[14429] | 102 | var perm = new Permutation(PermutationTypes.Absolute, qap.Weights.Rows, random);
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[14690] | 103 | if (LocalOptima) {
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| 104 | var fit = new DoubleValue(QAPEvaluator.Apply(perm, qap.Weights, qap.Distances));
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| 105 | QAPExhaustiveSwap2LocalImprovement.ImproveFast(perm, qap.Weights, qap.Distances, fit, new IntValue(0), new IntValue(0), qap.Maximization.Value, int.MaxValue, CancellationToken.None);
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| 106 | }
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[14429] | 107 | var permutations = new List<Permutation> { perm };
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| 108 | while (permutations.Count < pathCount + 1) {
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| 109 | perm = (Permutation)permutations.Last().Clone();
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| 110 | BiasedShuffle(perm, random);
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[14690] | 111 | if (LocalOptima) {
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| 112 | var fit = new DoubleValue(QAPEvaluator.Apply(perm, qap.Weights, qap.Distances));
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| 113 | QAPExhaustiveSwap2LocalImprovement.ImproveFast(perm, qap.Weights, qap.Distances, fit, new IntValue(0), new IntValue(0), qap.Maximization.Value, int.MaxValue, CancellationToken.None);
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| 114 | }
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| 115 | if (HammingSimilarityCalculator.CalculateSimilarity(permutations.Last(), perm) < 0.75)
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| 116 | permutations.Add(perm);
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[14429] | 117 | }
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[13861] | 118 |
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[14429] | 119 | var trajectories = Run(random, (QuadraticAssignmentProblem)Problem, permutations, BestImprovement).ToList();
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[14691] | 120 | var result = PermutationPathAnalysis.GetCharacteristics(trajectories);
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[14429] | 121 |
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| 122 | foreach (var chara in characteristics.CheckedItems.Select(x => x.Value.Value)) {
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[14691] | 123 | if (chara == "Swap2.Sharpness") yield return new Result("Swap2.Sharpness", new DoubleValue(result.Sharpness));
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| 124 | if (chara == "Swap2.Bumpiness") yield return new Result("Swap2.Bumpiness", new DoubleValue(result.Bumpiness));
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| 125 | if (chara == "Swap2.Flatness") yield return new Result("Swap2.Flatness", new DoubleValue(result.Flatness));
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[14429] | 126 | }
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| 127 | }
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[13861] | 128 |
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[14429] | 129 | public static IEnumerable<List<Tuple<Permutation, double>>> Run(IRandom random, QuadraticAssignmentProblem qap, IEnumerable<Permutation> permutations, bool bestImprovement = true) {
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| 130 | var iter = permutations.GetEnumerator();
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| 131 | if (!iter.MoveNext()) yield break;
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[13861] | 132 |
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[14678] | 133 | var min = qap.LowerBound.Value;
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| 134 | var max = qap.AverageQuality.Value;
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| 135 |
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[14429] | 136 | var start = iter.Current;
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| 137 | while (iter.MoveNext()) {
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| 138 | var end = iter.Current;
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[13861] | 139 |
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[14429] | 140 | var walk = (bestImprovement ? BestDirectedWalk(qap, start, end) : FirstDirectedWalk(random, qap, start, end)).ToList();
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[14678] | 141 | yield return walk.Select(x => Tuple.Create(x.Item1, (x.Item2 - min) / (max - min))).ToList();
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[14429] | 142 | start = end;
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| 143 | } // end paths
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| 144 | }
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[13861] | 145 |
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[14691] | 146 | private static IEnumerable<Tuple<Permutation, double>> BestDirectedWalk(QuadraticAssignmentProblem qap, Permutation start, Permutation end) {
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[13861] | 147 | var N = qap.Weights.Rows;
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| 148 | var sol = start;
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[14429] | 149 | var fitness = QAPEvaluator.Apply(sol, qap.Weights, qap.Distances);
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| 150 | yield return Tuple.Create(sol, fitness);
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| 151 |
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[13861] | 152 | var invSol = GetInverse(sol);
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| 153 | // we require at most N-1 steps to move from one permutation to another
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| 154 | for (var step = 0; step < N - 1; step++) {
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| 155 | var bestFitness = double.MaxValue;
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| 156 | var bestIndex = -1;
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| 157 | sol = (Permutation)sol.Clone();
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| 158 | for (var index = 0; index < N; index++) {
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| 159 | if (sol[index] == end[index]) continue;
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| 160 | var fit = QAPSwap2MoveEvaluator.Apply(sol, new Swap2Move(index, invSol[end[index]]), qap.Weights, qap.Distances);
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| 161 | if (fit < bestFitness) { // QAP is minimization
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| 162 | bestFitness = fit;
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| 163 | bestIndex = index;
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| 164 | }
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| 165 | }
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| 166 | if (bestIndex >= 0) {
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| 167 | var prev = sol[bestIndex];
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| 168 | Swap2Manipulator.Apply(sol, bestIndex, invSol[end[bestIndex]]);
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| 169 | fitness += bestFitness;
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| 170 | yield return Tuple.Create(sol, fitness);
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| 171 | invSol[prev] = invSol[end[bestIndex]];
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| 172 | invSol[sol[bestIndex]] = bestIndex;
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| 173 | } else break;
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| 174 | }
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| 175 | }
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| 176 |
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[14691] | 177 | private static IEnumerable<Tuple<Permutation, double>> FirstDirectedWalk(IRandom random, QuadraticAssignmentProblem qap, Permutation start, Permutation end) {
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[13861] | 178 | var N = qap.Weights.Rows;
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| 179 | var sol = start;
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[14429] | 180 | var fitness = QAPEvaluator.Apply(sol, qap.Weights, qap.Distances);
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| 181 | yield return Tuple.Create(sol, fitness);
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| 182 |
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[13861] | 183 | var invSol = GetInverse(sol);
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| 184 | // randomize the order in which improvements are tried
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| 185 | var order = Enumerable.Range(0, N).Shuffle(random).ToArray();
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| 186 | // we require at most N-1 steps to move from one permutation to another
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| 187 | for (var step = 0; step < N - 1; step++) {
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| 188 | var bestFitness = double.MaxValue;
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| 189 | var bestIndex = -1;
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| 190 | sol = (Permutation)sol.Clone();
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| 191 | for (var i = 0; i < N; i++) {
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| 192 | var index = order[i];
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| 193 | if (sol[index] == end[index]) continue;
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| 194 | var fit = QAPSwap2MoveEvaluator.Apply(sol, new Swap2Move(index, invSol[end[index]]), qap.Weights, qap.Distances);
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| 195 | if (fit < bestFitness) { // QAP is minimization
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| 196 | bestFitness = fit;
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| 197 | bestIndex = index;
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| 198 | if (bestFitness < 0) break;
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| 199 | }
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| 200 | }
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| 201 | if (bestIndex >= 0) {
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| 202 | var prev = sol[bestIndex];
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| 203 | Swap2Manipulator.Apply(sol, bestIndex, invSol[end[bestIndex]]);
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| 204 | fitness += bestFitness;
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| 205 | yield return Tuple.Create(sol, fitness);
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| 206 | invSol[prev] = invSol[end[bestIndex]];
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| 207 | invSol[sol[bestIndex]] = bestIndex;
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| 208 | } else break;
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| 209 | }
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| 210 | }
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| 211 |
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| 212 | private static int[] GetInverse(Permutation p) {
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| 213 | var inv = new int[p.Length];
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[14429] | 214 | for (var i = 0; i < p.Length; i++) {
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| 215 | inv[p[i]] = i;
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| 216 | }
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[13861] | 217 | return inv;
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| 218 | }
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| 219 |
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[14429] | 220 | // permutation must be strictly different in every position
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| 221 | private static void BiasedShuffle(Permutation p, IRandom random) {
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| 222 | for (var i = p.Length - 1; i > 0; i--) {
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| 223 | // Swap element "i" with a random earlier element (excluding itself)
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| 224 | var swapIndex = random.Next(i);
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| 225 | var h = p[swapIndex];
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| 226 | p[swapIndex] = p[i];
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| 227 | p[i] = h;
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| 228 | }
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[13861] | 229 | }
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| 230 | }
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| 231 | }
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