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 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 HeuristicLab.Data;
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26 | using HeuristicLab.Parameters;
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27 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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28 |
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29 | namespace HeuristicLab.Problems.VehicleRouting.Encodings.Prins {
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30 | [Item("PrinsStochasticLSManipulator", "An operator which manipulates a VRP representation by using the stochastic version of the Prins local search. It is implemented as described in Prins, C. (2004). A simple and effective evolutionary algorithm for the vehicle routing problem. Computers & Operations Research, 12:1985-2002.")]
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31 | [StorableClass]
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32 | public sealed class PrinsStochasticLSManipulator : PrinsLSManipulator {
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33 | public IValueParameter<IntValue> SampleSize {
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34 | get { return (IValueParameter<IntValue>)Parameters["SampleSize"]; }
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35 | }
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36 |
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37 | [StorableConstructor]
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38 | private PrinsStochasticLSManipulator(bool deserializing) : base(deserializing) { }
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39 |
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40 | public PrinsStochasticLSManipulator()
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41 | : base() {
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42 | Parameters.Add(new ValueParameter<IntValue>("SampleSize", "The sample size.", new IntValue(200)));
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43 | }
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44 |
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45 | public override IDeepCloneable Clone(Cloner cloner) {
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46 | return new PrinsStochasticLSManipulator(this, cloner);
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47 | }
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48 |
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49 | private PrinsStochasticLSManipulator(PrinsStochasticLSManipulator original, Cloner cloner)
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50 | : base(original, cloner) {
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51 | }
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52 |
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53 | protected override void Manipulate(IRandom random, PrinsEncoding individual) {
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54 | List<Tour> tours = individual.GetTours();
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55 | bool improvement = false;
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56 | int iterations = 0;
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57 |
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58 | do {
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59 | improvement = false;
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60 | double originalQuality = GetQuality(individual);
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61 | PrinsEncoding child = null;
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62 |
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63 | int samples = 0;
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64 | while (!improvement &&
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65 | samples < SampleSize.Value.Value) {
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66 | int u = random.Next(ProblemInstance.Cities.Value);
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67 | int v = random.Next(ProblemInstance.Cities.Value);
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68 |
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69 | child = Manipulate(individual,
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70 | originalQuality, u, v);
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71 |
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72 | improvement = child != null;
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73 |
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74 | samples++;
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75 | }
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76 |
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77 | if (improvement) {
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78 | for (int i = 0; i < child.Length; i++) {
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79 | individual[i] = child[i];
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80 | }
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81 | }
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82 |
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83 | iterations++;
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84 | } while (improvement &&
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85 | iterations < Iterations.Value.Value);
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86 | }
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87 | }
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88 | }
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