1 | #region License Information
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2 | /* HeuristicLab
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3 | * Copyright (C) 2002-2010 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.Core;
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26 | using HeuristicLab.Data;
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27 | using HeuristicLab.Parameters;
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28 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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29 |
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30 | namespace HeuristicLab.Selection {
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31 | /// <summary>
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32 | /// A quality proportional selection operator which considers a single double quality value for selection.
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33 | /// </summary>
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34 | [Item("ProportionalSelector", "A quality proportional selection operator which considers a single double quality value for selection.")]
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35 | [EmptyStorableClass]
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36 | [Creatable("Test")]
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37 | public sealed class ProportionalSelector : StochasticSingleObjectiveSelector {
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38 | private ValueParameter<BoolData> WindowingParameter {
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39 | get { return (ValueParameter<BoolData>)Parameters["Windowing"]; }
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40 | }
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41 |
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42 | public BoolData Windowing {
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43 | get { return WindowingParameter.Value; }
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44 | set { WindowingParameter.Value = value; }
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45 | }
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46 |
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47 | public ProportionalSelector()
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48 | : base() {
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49 | Parameters.Add(new ValueParameter<BoolData>("Windowing", "Apply windowing strategy (selection probability is proportional to the quality differences and not to the total quality).", new BoolData(true)));
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50 | CopySelected.Value = true;
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51 | }
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52 |
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53 | protected override IScope[] Select(List<IScope> scopes) {
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54 | int count = NumberOfSelectedSubScopesParameter.ActualValue.Value;
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55 | bool copy = CopySelectedParameter.Value.Value;
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56 | IRandom random = RandomParameter.ActualValue;
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57 | bool maximization = MaximizationParameter.ActualValue.Value;
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58 | bool windowing = WindowingParameter.Value.Value;
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59 | IScope[] selected = new IScope[count];
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60 |
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61 | // prepare qualities for proportional selection
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62 | var qualities = QualityParameter.ActualValue.Select(x => x.Value);
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63 | double minQuality = qualities.Min();
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64 | double maxQuality = qualities.Max();
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65 | if (minQuality == maxQuality) { // all quality values are equal
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66 | qualities = qualities.Select(x => 1.0);
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67 | } else {
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68 | if (windowing) {
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69 | if (maximization)
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70 | qualities = qualities.Select(x => x - minQuality);
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71 | else
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72 | qualities = qualities.Select(x => maxQuality - x);
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73 | } else {
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74 | if (minQuality < 0.0) throw new InvalidOperationException("Proportional selection without windowing does not work with quality values < 0.");
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75 | if (!maximization) {
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76 | double limit = Math.Min(maxQuality * 2, double.MaxValue);
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77 | qualities = qualities.Select(x => limit - x);
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78 | }
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79 | }
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80 | }
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81 |
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82 | List<double> list = qualities.ToList();
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83 | double qualitySum = qualities.Sum();
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84 | for (int i = 0; i < count; i++) {
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85 | double selectedQuality = random.NextDouble() * qualitySum;
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86 | int index = 0;
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87 | double currentQuality = list[index];
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88 | while (currentQuality < selectedQuality) {
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89 | index++;
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90 | currentQuality += list[index];
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91 | }
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92 | if (copy)
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93 | selected[i] = (IScope)scopes[index].Clone();
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94 | else {
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95 | selected[i] = scopes[index];
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96 | scopes.RemoveAt(index);
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97 | qualitySum -= list[index];
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98 | list.RemoveAt(index);
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99 | }
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100 | }
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101 | return selected;
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102 | }
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103 | }
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104 | }
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