[8894] | 1 | #region License Information
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| 2 | /* HeuristicLab
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[14185] | 3 | * Copyright (C) 2002-2016 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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[8894] | 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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[14927] | 25 | using HeuristicLab.Persistence;
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[8894] | 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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[14927] | 33 | [StorableType("29fcb891-4cc5-4542-9fa0-b082014f0e64")]
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[8894] | 34 | public sealed class VRPIntraRouteImprovementOperator : VRPImprovementOperator {
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| 35 | [StorableConstructor]
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| 36 | private VRPIntraRouteImprovementOperator(bool deserializing) : base(deserializing) { }
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[8899] | 37 | private VRPIntraRouteImprovementOperator(VRPIntraRouteImprovementOperator original, Cloner cloner) : base(original, cloner) { }
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[8894] | 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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