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.BinaryVectorEncoding;
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29 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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30 |
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31 | namespace HeuristicLab.Algorithms.ScatterSearch.Knapsack {
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32 | /// <summary>
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33 | /// An operator that relinks paths between knapsack solutions starting from both ends.
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34 | /// </summary>
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35 | [Item("KnapsackSimultaneousPathRelinker", "An operator that relinks paths between knapsack solutions starting from both ends.")]
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36 | [StorableClass]
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37 | public sealed class KnapsackSimultaneousPathRelinker : PathRelinker {
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38 | [StorableConstructor]
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39 | private KnapsackSimultaneousPathRelinker(bool deserializing) : base(deserializing) { }
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40 | private KnapsackSimultaneousPathRelinker(KnapsackSimultaneousPathRelinker original, Cloner cloner) : base(original, cloner) { }
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41 | public KnapsackSimultaneousPathRelinker()
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42 | : base() {
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43 | ParentsParameter.ActualName = "KnapsackSolution";
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44 | }
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45 |
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46 | public override IDeepCloneable Clone(Cloner cloner) {
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47 | return new KnapsackSimultaneousPathRelinker(this, cloner);
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48 | }
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49 |
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50 | public static ItemArray<IItem> Apply(IItem initiator, IItem guide, PercentValue n) {
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51 | if (!(initiator is BinaryVector) || !(guide is BinaryVector))
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52 | throw new ArgumentException("Cannot relink path because one of the provided solutions or both have the wrong type.");
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53 | if (n.Value <= 0.0)
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54 | throw new ArgumentException("RelinkingAccuracy must be greater than 0.");
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55 |
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56 | var firstInitiator = initiator.Clone() as BinaryVector;
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57 | var firstGuide = guide.Clone() as BinaryVector;
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58 | var secondInitiator = firstGuide.Clone() as BinaryVector;
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59 | var secondGuide = firstInitiator.Clone() as BinaryVector;
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60 |
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61 | if (firstInitiator.Length != firstGuide.Length)
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62 | throw new ArgumentException("The solutions are of different length.");
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63 |
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64 | var solutions = new List<BinaryVector>();
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65 | for (int i = 0; i < firstInitiator.Length / 2; i++) {
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66 | if (firstInitiator[i] != firstGuide[i]) {
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67 | firstInitiator[i] = firstGuide[i];
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68 | solutions.Add(firstInitiator.Clone() as BinaryVector);
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69 | }
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70 | var j = secondInitiator.Length - 1 - i;
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71 | if (secondInitiator[j] != secondGuide[j]) {
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72 | secondInitiator[j] = secondGuide[j];
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73 | solutions.Add(secondInitiator.Clone() as BinaryVector);
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74 | }
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75 | }
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76 |
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77 | var selection = new List<IItem>();
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78 | if (solutions.Count > 0) {
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79 | var noSol = (int)Math.Round(solutions.Count * n.Value);
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80 | if (noSol <= 0) noSol++;
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81 | var stepSize = (double)solutions.Count / (double)noSol;
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82 | for (int i = 0; i < noSol; i++)
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83 | selection.Add(solutions.ElementAt((int)Math.Round((i + 1) * stepSize - stepSize * 0.5)));
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84 | }
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85 |
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86 | return new ItemArray<IItem>(selection);
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87 | }
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88 |
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89 | protected override ItemArray<IItem> Relink(ItemArray<IItem> parents, PercentValue n) {
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90 | if (parents.Length != 2)
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91 | throw new ArgumentException("The number of parents is not equal to 2.");
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92 | return Apply(parents[0], parents[1], n);
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93 | }
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94 | }
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95 | }
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