1 | #region License Information
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2 | /* HeuristicLab
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3 | * Copyright (C) 2002-2012 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.Collections.Generic;
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24 | using System.Linq;
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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.Parameters;
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30 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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31 | using HeuristicLab.Problems.GeneralizedQuadraticAssignment.Common;
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32 |
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33 | namespace HeuristicLab.Problems.GeneralizedQuadraticAssignment {
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34 | [Item("GreedyRandomizedSolutionCreator", "Creates a solution according to the procedure 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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35 | [StorableClass]
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36 | public class GreedyRandomizedSolutionCreator : GQAPStochasticSolutionCreator {
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37 |
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38 | public IValueLookupParameter<IntValue> MaximumTriesParameter {
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39 | get { return (IValueLookupParameter<IntValue>)Parameters["MaximumTries"]; }
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40 | }
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41 |
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42 | [StorableConstructor]
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43 | protected GreedyRandomizedSolutionCreator(bool deserializing) : base(deserializing) { }
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44 | protected GreedyRandomizedSolutionCreator(GreedyRandomizedSolutionCreator original, Cloner cloner)
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45 | : base(original, cloner) { }
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46 | public GreedyRandomizedSolutionCreator()
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47 | : base() {
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48 | Parameters.Add(new ValueLookupParameter<IntValue>("MaximumTries", "The maximum number of tries to create a feasible solution.", new IntValue(10000)));
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49 | }
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50 |
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51 | public override IDeepCloneable Clone(Cloner cloner) {
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52 | return new GreedyRandomizedSolutionCreator(this, cloner);
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53 | }
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54 |
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55 | protected override IntegerVector CreateRandomSolution(IRandom random, DoubleArray demands, DoubleArray capacities) {
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56 | int tries = 0, maxTries = MaximumTriesParameter.ActualValue.Value;
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57 | var assignment = new Dictionary<int, int>();
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58 | var slack = new Dictionary<int, double>();
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59 |
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60 | while (tries < maxTries) {
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61 | assignment.Clear();
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62 | slack = capacities.Select((v, i) => new { Index = i, Value = v }).ToDictionary(x => x.Index, y => y.Value);
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63 | HashSet<int> CF = new HashSet<int>(), // set of chosen facilities / equipments
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64 | T = new HashSet<int>(), // set of facilities / equpiments that can be assigned to the set of chosen locations (CL)
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65 | CL = new HashSet<int>(), // set of chosen locations
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66 | F = new HashSet<int>(Enumerable.Range(0, demands.Length)), // set of (initially) all facilities / equipments
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67 | L = new HashSet<int>(Enumerable.Range(0, capacities.Length)); // set of (initially) all locations
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68 |
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69 | double threshold = 1.0;
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70 | do {
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71 | if (L.Any() && random.NextDouble() < threshold) {
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72 | int l = L.ChooseUniformRandom(random);
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73 | L.Remove(l);
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74 | CL.Add(l);
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75 | T = new HashSet<int>(WithDemandEqualOrLess(F, GetMaximumSlack(slack, CL), demands));
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76 | }
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77 | if (T.Any()) {
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78 | int f = T.ChooseUniformRandom(random);
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79 | T.Remove(f);
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80 | F.Remove(f);
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81 | CF.Add(f);
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82 | int l = WithSlackGreaterOrEqual(CL, demands[f], slack).ChooseUniformRandom(random);
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83 | assignment.Add(f, l);
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84 | slack[l] -= demands[f];
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85 | T = new HashSet<int>(WithDemandEqualOrLess(F, GetMaximumSlack(slack, CL), demands));
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86 | threshold = 1.0 - (double)T.Count / Math.Max(F.Count, 1.0);
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87 | }
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88 | } while (T.Any() || L.Any());
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89 | tries++;
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90 | if (!F.Any()) break;
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91 | }
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92 |
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93 | if (assignment.Count != demands.Length) throw new InvalidOperationException(String.Format("No solution could be found in {0} tries.", maxTries));
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94 |
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95 | return new IntegerVector(assignment.OrderBy(x => x.Key).Select(x => x.Value).ToArray());
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96 | }
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97 |
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98 | private static IEnumerable<int> WithDemandEqualOrLess(IEnumerable<int> facilities, double maximum, DoubleArray demands) {
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99 | foreach (int f in facilities) {
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100 | if (demands[f] <= maximum) yield return f;
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101 | }
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102 | }
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103 |
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104 | private static double GetMaximumSlack(Dictionary<int, double> slack, HashSet<int> CL) {
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105 | return slack.Where(x => CL.Contains(x.Key)).Select(x => x.Value).Max();
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106 | }
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107 |
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108 | private static IEnumerable<int> WithSlackGreaterOrEqual(HashSet<int> locations, double minimum, Dictionary<int, double> slack) {
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109 | foreach (int l in locations) {
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110 | if (slack[l] >= minimum) yield return l;
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111 | }
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112 | }
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113 | }
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114 | }
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