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.Collections.ObjectModel;
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25 | using System.Linq;
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26 | using HeuristicLab.Collections;
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27 | using HeuristicLab.Common;
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28 | using HeuristicLab.Core;
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29 | using HeuristicLab.Data;
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30 | using HeuristicLab.Parameters;
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31 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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32 |
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33 | namespace HeuristicLab.Operators {
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34 | /// <summary>
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35 | /// Branch of operators that have different probabilities to get executed.
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36 | /// </summary>
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37 | [Item("StochasticMultiBranch", "Branch of operators that have different probabilities to get executed.")]
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38 | [StorableClass]
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39 | public class StochasticMultiBranch : MultiOperator<IOperator> {
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40 | public ValueLookupParameter<DoubleArray> ProbabilitiesParameter {
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41 | get { return (ValueLookupParameter<DoubleArray>)Parameters["Probabilities"]; }
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42 | }
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43 | public ILookupParameter<IRandom> RandomParameter {
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44 | get { return (ILookupParameter<IRandom>)Parameters["Random"]; }
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45 | }
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46 |
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47 | public DoubleArray Probabilities {
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48 | get { return ProbabilitiesParameter.Value; }
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49 | set { ProbabilitiesParameter.Value = value; }
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50 | }
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51 |
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52 | [StorableConstructor]
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53 | public StochasticMultiBranch(bool deserializing) : base() { }
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54 | /// <summary>
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55 | /// Initializes a new instance of <see cref="StochasticMultiBranch"/> with two parameters
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56 | /// (<c>Probabilities</c> and <c>Random</c>).
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57 | /// </summary>
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58 | public StochasticMultiBranch()
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59 | : base() {
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60 | Parameters.Add(new ValueLookupParameter<DoubleArray>("Probabilities", "The array of relative probabilities for each operator.", new DoubleArray()));
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61 | Parameters.Add(new LookupParameter<IRandom>("Random", "The random number generator to use."));
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62 | Initialize();
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63 | }
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64 |
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65 | [StorableHook(HookType.AfterDeserialization)]
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66 | private void Initialize() {
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67 | Operators.ItemsAdded += new CollectionItemsChangedEventHandler<IndexedItem<IOperator>>(Operators_ItemsAdded);
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68 | Operators.ItemsRemoved += new CollectionItemsChangedEventHandler<IndexedItem<IOperator>>(Operators_ItemsRemoved);
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69 | Operators.ItemsMoved += new CollectionItemsChangedEventHandler<IndexedItem<IOperator>>(Operators_ItemsMoved);
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70 | }
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71 |
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72 | void Operators_ItemsMoved(object sender, CollectionItemsChangedEventArgs<IndexedItem<IOperator>> e) {
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73 | if (Probabilities != null) {
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74 | DoubleArray oldProb = (DoubleArray)Probabilities.Clone();
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75 | foreach (IndexedItem<IOperator> old in e.OldItems) {
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76 | foreach (IndexedItem<IOperator> item in e.Items) {
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77 | if (old.Value == item.Value && item.Index < Probabilities.Length && old.Index < oldProb.Length)
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78 | Probabilities[item.Index] = oldProb[old.Index];
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79 | }
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80 | }
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81 | }
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82 | }
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83 |
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84 | void Operators_ItemsRemoved(object sender, CollectionItemsChangedEventArgs<IndexedItem<IOperator>> e) {
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85 | if (Probabilities != null && Probabilities.Length > Operators.Count) {
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86 | List<double> probs = new List<double>(Probabilities.Cast<DoubleValue>().Select(x => x.Value));
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87 | var sorted = e.Items.OrderByDescending(x => x.Index);
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88 | foreach (IndexedItem<IOperator> item in sorted)
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89 | if (probs.Count > item.Index) probs.RemoveAt(item.Index);
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90 | Probabilities = new DoubleArray(probs.ToArray());
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91 | }
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92 | }
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93 |
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94 | private void Operators_ItemsAdded(object sender, HeuristicLab.Collections.CollectionItemsChangedEventArgs<IndexedItem<IOperator>> e) {
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95 | if (Probabilities != null && Probabilities.Length < Operators.Count) {
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96 | DoubleArray probs = new DoubleArray(Operators.Count);
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97 | double avg = 0;
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98 | if (Probabilities.Length > 0) {
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99 | for (int i = 0; i < Probabilities.Length; i++)
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100 | avg += Probabilities[i];
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101 | avg /= (double)Probabilities.Length;
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102 | } else avg = 1;
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103 |
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104 | var added = e.Items.OrderBy(x => x.Index).ToList();
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105 | int insertCount = 0;
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106 | for (int i = 0; i < Operators.Count; i++) {
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107 | if (insertCount < added.Count && i == added[insertCount].Index) {
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108 | probs[i] = avg;
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109 | insertCount++;
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110 | } else if (i - insertCount < Probabilities.Length) {
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111 | probs[i] = Probabilities[i - insertCount];
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112 | } else probs[i] = avg;
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113 | }
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114 | Probabilities = probs;
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115 | }
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116 | }
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117 |
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118 | /// <summary>
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119 | /// Applies an operator of the branches to the current scope with a
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120 | /// specific probability.
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121 | /// </summary>
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122 | /// <exception cref="InvalidOperationException">Thrown when the list of probabilites does not
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123 | /// match the number of operators.</exception>
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124 | /// <returns>A new operation with the operator that was selected followed by the current operator's successor.</returns>
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125 | public override IOperation Apply() {
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126 | IRandom random = RandomParameter.ActualValue;
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127 | DoubleArray probabilities = ProbabilitiesParameter.ActualValue;
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128 | if(probabilities.Length != Operators.Count) {
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129 | throw new InvalidOperationException("StochasticMultiBranch: The list of probabilities has to match the number of operators");
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130 | }
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131 | double sum = 0;
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132 | for (int i = 0; i < Operators.Count; i++) {
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133 | sum += probabilities[i];
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134 | }
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135 | double r = random.NextDouble() * sum;
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136 | sum = 0;
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137 | IOperator successor = null;
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138 | for(int i = 0; i < Operators.Count; i++) {
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139 | sum += probabilities[i];
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140 | if(sum > r) {
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141 | successor = Operators[i];
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142 | break;
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143 | }
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144 | }
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145 | OperationCollection next = new OperationCollection(base.Apply());
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146 | if (successor != null) {
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147 | next.Insert(0, ExecutionContext.CreateOperation(successor));
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148 | }
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149 | return next;
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150 | }
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151 | }
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152 | }
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