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.Collections;
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26 | using HeuristicLab.Core;
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27 | using HeuristicLab.Data;
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28 | using HeuristicLab.Parameters;
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29 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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30 | using HeuristicLab.PluginInfrastructure;
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31 |
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32 | namespace HeuristicLab.Operators {
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33 | /// <summary>
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34 | /// Selects one of its branches (if there are any) given a list of relative probabilities.
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35 | /// </summary>
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36 | [Item("StochasticMultiBranch<T>", "Selects one of its branches (if there are any) given a list of relative probabilities.")]
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37 | [StorableClass]
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38 | public abstract class StochasticMultiBranch<T> : CheckedMultiOperator<T> where T : class, IOperator {
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39 | /// <summary>
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40 | /// Should return true if the StochasticMultiOperator should create a new child operation with the selected successor
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41 | /// or if it should create a new operation. If you need to shield the parameters of the successor you should return true here.
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42 | /// </summary>
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43 | protected abstract bool CreateChildOperation { get; }
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44 |
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45 | public ValueLookupParameter<DoubleArray> ProbabilitiesParameter {
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46 | get { return (ValueLookupParameter<DoubleArray>)Parameters["Probabilities"]; }
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47 | }
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48 | public ILookupParameter<IRandom> RandomParameter {
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49 | get { return (ILookupParameter<IRandom>)Parameters["Random"]; }
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50 | }
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51 |
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52 | public DoubleArray Probabilities {
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53 | get { return ProbabilitiesParameter.Value; }
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54 | set { ProbabilitiesParameter.Value = value; }
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55 | }
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56 |
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57 | [StorableConstructor]
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58 | protected StochasticMultiBranch(bool deserializing) : base(deserializing) { }
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59 | /// <summary>
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60 | /// Initializes a new instance of <see cref="StochasticMultiOperator"/> with two parameters
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61 | /// (<c>Probabilities</c> and <c>Random</c>).
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62 | /// </summary>
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63 | public StochasticMultiBranch()
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64 | : base() {
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65 | Parameters.Add(new ValueLookupParameter<DoubleArray>("Probabilities", "The array of relative probabilities for each operator.", new DoubleArray()));
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66 | Parameters.Add(new LookupParameter<IRandom>("Random", "The random number generator to use."));
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67 | }
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68 |
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69 | protected override void Operators_ItemsRemoved(object sender, CollectionItemsChangedEventArgs<IndexedItem<T>> e) {
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70 | base.Operators_ItemsRemoved(sender, e);
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71 | if (Probabilities != null && Probabilities.Length > Operators.Count) {
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72 | List<double> probs = new List<double>(Probabilities.Cast<double>());
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73 | var sorted = e.Items.OrderByDescending(x => x.Index);
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74 | foreach (IndexedItem<T> item in sorted)
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75 | if (probs.Count > item.Index) probs.RemoveAt(item.Index);
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76 | Probabilities = new DoubleArray(probs.ToArray());
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77 | }
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78 | }
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79 |
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80 | protected override void Operators_ItemsAdded(object sender, HeuristicLab.Collections.CollectionItemsChangedEventArgs<IndexedItem<T>> e) {
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81 | base.Operators_ItemsAdded(sender, e);
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82 | if (Probabilities != null && Probabilities.Length < Operators.Count) {
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83 | double avg = (Probabilities.Where(x => x > 0).Count() > 0) ? (Probabilities.Where(x => x > 0).Average()) : (1);
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84 | // add the average of all probabilities in the respective places (the new operators)
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85 | var added = e.Items.OrderBy(x => x.Index).ToList();
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86 | int insertCount = 0;
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87 | DoubleArray probs = new DoubleArray(Operators.Count);
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88 | for (int i = 0; i < Operators.Count; i++) {
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89 | if (insertCount < added.Count && i == added[insertCount].Index) {
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90 | probs[i] = avg;
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91 | insertCount++;
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92 | } else if (i - insertCount < Probabilities.Length) {
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93 | probs[i] = Probabilities[i - insertCount];
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94 | } else probs[i] = avg;
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95 | }
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96 | Probabilities = probs;
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97 | }
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98 | }
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99 |
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100 | /// <summary>
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101 | /// Applies an operator of the branches to the current scope with a
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102 | /// specific probability.
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103 | /// </summary>
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104 | /// <exception cref="InvalidOperationException">Thrown when the list of probabilites does not
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105 | /// match the number of operators, the list of selected operators is empty,
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106 | /// or all selected operators have zero probabitlity.</exception>
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107 | /// <returns>A new operation with the operator that was selected followed by the current operator's successor.</returns>
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108 | public override IOperation Apply() {
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109 | IRandom random = RandomParameter.ActualValue;
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110 | DoubleArray probabilities = ProbabilitiesParameter.ActualValue;
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111 | if (probabilities.Length != Operators.Count) {
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112 | throw new InvalidOperationException(Name + ": The list of probabilities has to match the number of operators");
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113 | }
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114 | IOperator successor = null;
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115 | var checkedOperators = Operators.CheckedItems;
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116 | if (checkedOperators.Count() > 0) {
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117 | // select a random operator from the checked operators
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118 | double sum = (from indexedItem in checkedOperators select probabilities[indexedItem.Index]).Sum();
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119 | if (sum == 0) throw new InvalidOperationException(Name + ": All selected operators have zero probability.");
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120 | double r = random.NextDouble() * sum;
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121 | sum = 0;
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122 | foreach (var indexedItem in checkedOperators) {
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123 | sum += probabilities[indexedItem.Index];
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124 | if (sum > r) {
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125 | successor = indexedItem.Value;
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126 | break;
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127 | }
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128 | }
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129 | }
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130 | OperationCollection next = new OperationCollection(base.Apply());
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131 | if (successor != null) {
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132 | if (CreateChildOperation)
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133 | next.Insert(0, ExecutionContext.CreateChildOperation(successor));
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134 | else next.Insert(0, ExecutionContext.CreateOperation(successor));
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135 | }
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136 | return next;
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137 | }
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138 | }
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139 |
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140 | /// <summary>
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141 | /// Selects one of its branches (if there are any) given a list of relative probabilities.
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142 | /// </summary>
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143 | [Item("StochasticMultiBranch", "Selects one of its branches (if there are any) given a list of relative probabilities.")]
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144 | [StorableClass]
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145 | public class StochasticMultiBranch : StochasticMultiBranch<IOperator> {
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146 | protected override bool CreateChildOperation {
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147 | get { return false; }
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148 | }
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149 | }
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150 | }
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