1 | #region License Information
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2 | /* HeuristicLab
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3 | * Copyright (C) 2002-2019 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.Collections.Generic;
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23 | using HeuristicLab.Common;
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24 | using HeuristicLab.Core;
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25 | using HEAL.Fossil;
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26 | using HeuristicLab.Problems.VehicleRouting.Encodings.Potvin;
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27 |
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28 | namespace HeuristicLab.Problems.VehicleRouting {
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29 | /// <summary>
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30 | /// An operator which improves VRP solutions.
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31 | /// </summary>
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32 | [Item("VRPIntraRouteImprovementOperator", "An operator which improves VRP solutions.")]
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33 | [StorableType("297EAEDF-FD4E-48E1-B304-C13699E78CDA")]
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34 | public sealed class VRPIntraRouteImprovementOperator : VRPImprovementOperator {
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35 | [StorableConstructor]
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36 | private VRPIntraRouteImprovementOperator(StorableConstructorFlag _) : base(_) { }
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37 | private VRPIntraRouteImprovementOperator(VRPIntraRouteImprovementOperator original, Cloner cloner) : base(original, cloner) { }
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38 | public VRPIntraRouteImprovementOperator() : base() { }
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39 |
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40 | public override IDeepCloneable Clone(Cloner cloner) {
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41 | return new VRPIntraRouteImprovementOperator(this, cloner);
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42 | }
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43 |
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44 | protected override int Improve(PotvinEncoding solution) {
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45 | int evaluatedSolutions = 0;
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46 |
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47 | var rand = RandomParameter.ActualValue;
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48 | var instance = ProblemInstance;
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49 | int sampleSize = SampleSizeParameter.Value.Value;
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50 | int attempts = ImprovementAttemptsParameter.Value.Value;
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51 | int customers = instance.Cities.Value;
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52 |
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53 | // store city-to-tour assignment and position of the city within the tour
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54 | var tours = new Dictionary<int, Tour>();
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55 | var position = new Dictionary<int, int>();
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56 | foreach (Tour tour in solution.Tours) {
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57 | for (int stop = 0; stop < tour.Stops.Count; stop++) {
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58 | int city = tour.Stops[stop];
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59 | tours[city] = tour;
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60 | position[city] = stop;
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61 | }
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62 | }
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63 |
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64 | for (int attempt = 0; attempt < attempts; attempt++) {
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65 | for (int sample = 0; sample < sampleSize; sample++) {
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66 | int chosenCust = 1 + rand.Next(customers);
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67 | var custTour = tours[chosenCust];
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68 |
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69 | double beforeQuality = instance.EvaluateTour(custTour, solution).Quality;
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70 | evaluatedSolutions++;
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71 |
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72 | custTour.Stops.RemoveAt(position[chosenCust]);
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73 | int place = solution.FindBestInsertionPlace(custTour, chosenCust);
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74 | evaluatedSolutions += custTour.Stops.Count;
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75 | custTour.Stops.Insert(place, chosenCust);
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76 |
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77 | if (place != position[chosenCust]) {
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78 | double afterQuality = instance.EvaluateTour(custTour, solution).Quality;
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79 | if (afterQuality > beforeQuality) {
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80 | // revert move
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81 | custTour.Stops.RemoveAt(place);
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82 | custTour.Stops.Insert(position[chosenCust], chosenCust);
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83 | } else {
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84 | // accept move and update positions of the cities within the tour
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85 | for (int stop = 0; stop < custTour.Stops.Count; stop++) {
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86 | int city = custTour.Stops[stop];
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87 | position[city] = stop;
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88 | }
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89 | break;
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90 | }
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91 | }
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92 | }
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93 | }
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94 |
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95 | return evaluatedSolutions;
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96 | }
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97 | }
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98 | }
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