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.Collections.Generic;
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23 | using System.Linq;
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24 | using HeuristicLab.Common;
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25 | using HeuristicLab.Core;
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26 | using HeuristicLab.Data;
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27 | using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
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28 | using HeuristicLab.Operators;
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29 | using HeuristicLab.Optimization;
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30 | using HeuristicLab.Parameters;
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31 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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32 | using HeuristicLab.Random;
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33 | using HeuristicLab.Selection;
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34 |
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35 | namespace HeuristicLab.EvolutionaryTracking.Analyzers {
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36 | /// <summary>
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37 | /// An analyzer that adapts selection pressure based on average three length
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38 | /// </summary>
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39 | [Item("SymbolicExpressionTreeRelativeLengthAnalyzer", "An analyzer that adapts selection pressure based on average three length")]
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40 | [StorableClass]
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41 | class SymbolicExpressionTreeRelativeLengthAnalyzer : SingleSuccessorOperator, IAnalyzer {
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42 | private const string UpdateIntervalParameterName = "UpdateInterval";
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43 | private const string UpdateCounterParameterName = "UpdateCounter";
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44 | private const string ResultsParameterName = "Results";
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45 | private const string GenerationsParameterName = "Generations";
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46 |
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47 | private const string ExpectedAverageTreeLenghtParameterName = "ExpectedAverageTreeLength";
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48 | private const string RandomSelectionWindowSizeParameterName = "RandomSelectionWindowSize";
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49 | private const string RandomSelectionGenerationsCounterParameterName = "RandomSelectionGenerationsCounter";
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50 | private const string UpperBoundingFactorParameterName = "UpperBoundingFactor";
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51 | private const string LowerBoundingFactorParameterName = "LowerBoundingFactor";
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52 | private const string ActualTournamentGroupSizeParameterName = "TournamentGroupSize";
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53 |
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54 | readonly MersenneTwister _random = new MersenneTwister(12345);
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55 |
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56 | #region Parameter properties
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57 | public ValueParameter<IntValue> UpdateIntervalParameter {
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58 | get { return (ValueParameter<IntValue>)Parameters[UpdateIntervalParameterName]; }
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59 | }
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60 | public ValueParameter<IntValue> UpdateCounterParameter {
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61 | get { return (ValueParameter<IntValue>)Parameters[UpdateCounterParameterName]; }
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62 | }
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63 | public LookupParameter<ResultCollection> ResultsParameter {
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64 | get { return (LookupParameter<ResultCollection>)Parameters[ResultsParameterName]; }
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65 | }
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66 | public LookupParameter<IntValue> GenerationsParameter {
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67 | get { return (LookupParameter<IntValue>)Parameters[GenerationsParameterName]; }
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68 | }
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69 | public ValueParameter<DoubleValue> ExpectedAverageTreeLengthParameter {
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70 | get { return (ValueParameter<DoubleValue>)Parameters[ExpectedAverageTreeLenghtParameterName]; }
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71 | }
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72 | public ValueParameter<DoubleValue> UpperBoundingFactorParameter {
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73 | get { return (ValueParameter<DoubleValue>)Parameters[UpperBoundingFactorParameterName]; }
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74 | }
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75 | public ValueParameter<DoubleValue> LowerBoundingFactorParameter {
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76 | get { return (ValueParameter<DoubleValue>)Parameters[LowerBoundingFactorParameterName]; }
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77 | }
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78 | public ValueParameter<IntValue> RandomSelectionWindowSizeParameter {
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79 | get { return (ValueParameter<IntValue>)Parameters[RandomSelectionWindowSizeParameterName]; }
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80 | }
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81 | public ValueParameter<IntValue> RandomSelectionGenerationsCounterParameter {
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82 | get { return (ValueParameter<IntValue>)Parameters[RandomSelectionGenerationsCounterParameterName]; }
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83 | }
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84 | public ValueParameter<IntValue> ActualTournamentGroupSizeParameter {
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85 | get { return (ValueParameter<IntValue>)Parameters[ActualTournamentGroupSizeParameterName]; }
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86 | }
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87 | #endregion
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88 |
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89 | #region Parameters
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90 | public bool EnabledByDefault {
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91 | get { return true; }
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92 | }
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93 | public IntValue UpdateInterval {
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94 | get { return UpdateIntervalParameter.Value; }
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95 | }
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96 | public IntValue UpdateCounter {
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97 | get { return UpdateCounterParameter.Value; }
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98 | }
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99 | public ResultCollection Results {
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100 | get { return ResultsParameter.ActualValue; }
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101 | }
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102 | public IntValue Generations {
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103 | get { return GenerationsParameter.ActualValue; }
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104 | }
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105 | public DoubleValue ExpectedAverageTreeLength {
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106 | get { return (DoubleValue)ExpectedAverageTreeLengthParameter.ActualValue; }
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107 | }
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108 | public IntValue RandomSelectionWindowSize {
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109 | get { return (IntValue)RandomSelectionWindowSizeParameter.ActualValue; }
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110 | }
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111 | public IntValue RandomSelectionGenerationsCounter {
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112 | get { return (IntValue)RandomSelectionGenerationsCounterParameter.ActualValue; }
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113 | }
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114 | public IntValue ActualTournamentGroupSize {
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115 | get { return (IntValue)ActualTournamentGroupSizeParameter.ActualValue; }
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116 | set { ActualTournamentGroupSizeParameter.ActualValue = value; }
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117 | }
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118 | public DoubleValue LowerBoundingFactor {
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119 | get { return (DoubleValue)LowerBoundingFactorParameter.ActualValue; }
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120 | }
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121 | public DoubleValue UpperBoundingFactor {
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122 | get { return (DoubleValue)UpperBoundingFactorParameter.ActualValue; }
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123 | }
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124 | #endregion
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125 |
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126 | [StorableConstructor]
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127 | protected SymbolicExpressionTreeRelativeLengthAnalyzer(bool deserializing)
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128 | : base() {
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129 | }
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130 | protected SymbolicExpressionTreeRelativeLengthAnalyzer(SymbolicExpressionTreeRelativeLengthAnalyzer original, Cloner cloner)
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131 | : base(original, cloner) {
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132 | }
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133 | public override IDeepCloneable Clone(Cloner cloner) {
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134 | return new SymbolicExpressionTreeRelativeLengthAnalyzer(this, cloner);
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135 | }
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136 | public SymbolicExpressionTreeRelativeLengthAnalyzer()
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137 | : base() {
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138 | Parameters.Add(new ValueParameter<IntValue>(UpdateIntervalParameterName, "The interval in which the tree length analysis should be applied.", new IntValue(1)));
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139 | Parameters.Add(new ValueParameter<IntValue>(UpdateCounterParameterName, "The value which counts how many times the operator was called since the last update", new IntValue(0)));
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140 | Parameters.Add(new ValueLookupParameter<ResultCollection>(ResultsParameterName, "The results collection where the analysis values should be stored."));
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141 | Parameters.Add(new LookupParameter<IntValue>(GenerationsParameterName, "The number of generations so far."));
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142 | Parameters.Add(new ValueParameter<DoubleValue>(ExpectedAverageTreeLenghtParameterName, "The expected statistical average of the tree length for given grammar and depth and random trees", new DoubleValue(0)));
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143 | Parameters.Add(new ValueParameter<DoubleValue>(UpperBoundingFactorParameterName, "Multiplier for the expected average size, giving the upper bound of the average size length", new DoubleValue(3.0)));
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144 | Parameters.Add(new ValueParameter<DoubleValue>(LowerBoundingFactorParameterName, "Multiplier for the expected average size, giving the lower bound of the average size length", new DoubleValue(2.0)));
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145 | Parameters.Add(new ValueParameter<IntValue>(RandomSelectionWindowSizeParameterName, "Maximum window for random selection (in generations)"));
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146 | Parameters.Add(new ValueParameter<IntValue>(RandomSelectionGenerationsCounterParameterName, "Counter for the consecutive random selection generations"));
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147 | Parameters.Add(new ValueParameter<IntValue>(ActualTournamentGroupSizeParameterName, "Parameter to store the actual tournament size so we can reuse it later.", new IntValue(0)));
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148 |
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149 | UpdateCounterParameter.Hidden = true;
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150 | UpdateIntervalParameter.Hidden = true;
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151 | }
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152 | #region After deserialization code
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153 | [StorableHook(HookType.AfterDeserialization)]
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154 | private void AfterDeserialization() {
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155 | // check if all the parameters are present and accounted for
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156 | if (!Parameters.ContainsKey(UpdateIntervalParameterName)) {
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157 | Parameters.Add(new ValueParameter<IntValue>(UpdateIntervalParameterName, "The interval in which the tree length analysis should be applied.", new IntValue(1)));
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158 | }
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159 | if (!Parameters.ContainsKey(UpdateCounterParameterName)) {
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160 | Parameters.Add(new ValueParameter<IntValue>(UpdateCounterParameterName, "The value which counts how many times the operator was called since the last update", new IntValue(0)));
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161 | UpdateCounterParameter.Hidden = true;
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162 | }
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163 | }
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164 | #endregion
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165 | #region IStatefulItem members
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166 | public override void InitializeState() {
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167 | base.InitializeState();
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168 | UpdateCounter.Value = 0;
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169 | }
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170 |
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171 | public override void ClearState() {
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172 | base.ClearState();
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173 | UpdateCounter.Value = 0;
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174 | }
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175 | #endregion
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176 |
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177 | public override IOperation Apply() {
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178 | UpdateCounter.Value++;
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179 | if (UpdateCounter.Value == UpdateInterval.Value) {
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180 | UpdateCounter.Value = 0;
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181 |
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182 | var gaContext = ExecutionContext.Parent.Parent;
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183 | var selectorParameter = gaContext.Parameters["Selector"];
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184 | var selector = selectorParameter.ActualValue as TournamentSelector;
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185 | var gScope = ExecutionContext.Scope;
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186 | while (gScope.Parent != null) gScope = gScope.Parent;
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187 |
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188 | if (Generations.Value == 0) {
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189 | UpdateCounter.Value = 0; // reset the update counter
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190 | if (ActualTournamentGroupSize.Value == 0)
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191 | ActualTournamentGroupSize = new IntValue(selector.GroupSizeParameter.Value.Value);
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192 | else
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193 | selector.GroupSizeParameter.Value = ActualTournamentGroupSize;
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194 |
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195 | // check the threshhold value by simulating the average tree length using the GrowTreeCreator
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196 | var randomTrees = new List<ISymbolicExpressionTree>();
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197 |
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198 | var problemContext = gaContext.Parent;
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199 |
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200 | var grammar = (ISymbolicExpressionGrammar)problemContext.Parameters["SymbolicExpressionTreeGrammar"].ActualValue;
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201 | var maxDepth = (IntValue)problemContext.Parameters["MaximumSymbolicExpressionTreeDepth"].ActualValue;
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202 |
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203 | long length = 0;
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204 | const uint size = 1000;
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205 | for (int i = 0; i != size; ++i) {
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206 | randomTrees.Add(GrowTreeCreator.Create(_random, grammar, 0, maxDepth.Value));
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207 | length += randomTrees.Last().Length;
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208 | }
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209 | ExpectedAverageTreeLength.Value = (double)length / size;
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210 |
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211 | return base.Apply();
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212 | } else if (Generations.Value >= 10) {
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213 | // this should provide a bloat control mechanism while allowing population diversity to increase
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214 | double currentAverageTreeLength = (from s in gScope.SubScopes
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215 | let tree = s.Variables.First().Value as ISymbolicExpressionTree
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216 | select tree.Length).Average();
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217 |
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218 | double expectedAverage = ExpectedAverageTreeLength.Value;
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219 |
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220 | if (currentAverageTreeLength >= UpperBoundingFactor.Value * expectedAverage) {
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221 | SetGroupSize(selector, 1);
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222 | }
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223 | if (RandomSelectionGenerationsCounter.Value == RandomSelectionWindowSize.Value ||
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224 | currentAverageTreeLength <= LowerBoundingFactor.Value * expectedAverage) {
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225 |
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226 | SetGroupSize(selector, ActualTournamentGroupSize.Value);
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227 | RandomSelectionGenerationsCounter.Value = 0;
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228 | } else {
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229 | RandomSelectionGenerationsCounter.Value++;
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230 | }
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231 | }
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232 | }
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233 | return base.Apply();
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234 | }
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235 |
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236 | void SetGroupSize(TournamentSelector ts, int value) {
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237 | ts.GroupSizeParameter.Value = new IntValue(value);
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238 | }
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239 | }
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240 | }
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