1 | #region License Information
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2 | /* HeuristicLab
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3 | * Copyright (C) 2002-2013 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 HeuristicLab.Common;
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25 | using HeuristicLab.Core;
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26 | using HeuristicLab.Encodings.IntegerVectorEncoding;
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27 | using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
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28 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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29 | using HeuristicLab.Random;
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30 |
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31 | namespace HeuristicLab.Problems.GrammaticalEvolution {
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32 | /// <summary>
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33 | /// DepthFirstMapper
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34 | /// </summary>
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35 | [Item("DepthFirstMapper", "")]
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36 | [StorableClass]
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37 | public class DepthFirstMapper : GenotypeToPhenotypeMapper {
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38 |
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39 | [StorableConstructor]
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40 | protected DepthFirstMapper(bool deserializing) : base(deserializing) { }
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41 | protected DepthFirstMapper(DepthFirstMapper original, Cloner cloner) : base(original, cloner) { }
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42 | public DepthFirstMapper() : base() { }
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43 |
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44 | public override IDeepCloneable Clone(Cloner cloner) {
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45 | return new DepthFirstMapper(this, cloner);
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46 | }
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47 |
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48 |
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49 | /// <summary>
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50 | /// Maps a genotype (an integer vector) to a phenotype (a symbolic expression tree).
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51 | /// Depth-first approach.
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52 | /// </summary>
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53 | /// <param name="grammar">grammar definition</param>
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54 | /// <param name="genotype">integer vector, which should be mapped to a tree</param>
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55 | /// <returns>phenotype (a symbolic expression tree)</returns>
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56 | public override SymbolicExpressionTree Map(ISymbolicExpressionGrammar grammar,
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57 | IntegerVector genotype) {
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58 |
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59 | SymbolicExpressionTree tree = new SymbolicExpressionTree();
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60 | var rootNode = (SymbolicExpressionTreeTopLevelNode)grammar.ProgramRootSymbol.CreateTreeNode();
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61 | if (rootNode.HasLocalParameters) rootNode.ResetLocalParameters(new MersenneTwister());
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62 | var startNode = (SymbolicExpressionTreeTopLevelNode)grammar.StartSymbol.CreateTreeNode();
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63 | if (startNode.HasLocalParameters) startNode.ResetLocalParameters(new MersenneTwister());
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64 | rootNode.AddSubtree(startNode);
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65 | tree.Root = rootNode;
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66 |
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67 | //int genotypeIndex = 0;
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68 | //int currSubtreeCount = 1;
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69 | //MapDepthFirstRecursively(startNode, genotype,
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70 | // grammar, genotype.Length,
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71 | // ref genotypeIndex, ref currSubtreeCount,
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72 | // new MersenneTwister());
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73 |
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74 | MapDepthFirstIteratively(startNode, genotype, grammar,
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75 | genotype.Length, new MersenneTwister());
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76 | return tree;
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77 | }
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78 |
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79 |
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80 | /// <summary>
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81 | /// Genotype-to-Phenotype mapper (recursive depth-first approach).
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82 | /// Appends maximum allowed children (non-terminal symbols) to
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83 | /// <paramref name="currentNode"/>, as long as <paramref name="currSubtreeCount"/>
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84 | /// doesn't exceed <paramref name="maxSubtreeCount"/>.
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85 | /// If at most <paramref name="maxSubtreeCount"/> subtrees were created,
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86 | /// each non-full node is filled with randomly chosen nodes
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87 | /// (non-terminal and terminal), and each non-terminal node is again filled with a terminal node.
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88 | /// </summary>
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89 | /// <param name="currentNode">current parent node</param>
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90 | /// <param name="genotype">integer vector, which should be mapped to a tree</param>
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91 | /// <param name="grammar">grammar to determine the allowed child symbols for currentNode </param>
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92 | /// <param name="maxSubtreeCount">maximum allowed subtrees (= number of used genomes)</param>
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93 | /// <param name="genotypeIndex">current index in integer vector</param>
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94 | /// <param name="currSubtreeCount">number of already determined subtrees (filled or still incomplete)</param>
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95 | private void MapDepthFirstRecursively(ISymbolicExpressionTreeNode currentNode,
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96 | IntegerVector genotype,
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97 | ISymbolicExpressionGrammar grammar,
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98 | int maxSubtreeCount,
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99 | ref int genotypeIndex,
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100 | ref int currSubtreeCount,
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101 | IRandom random) {
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102 |
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103 | // TODO: check, if method calls of GetNewChildNode() and GetRandomTerminalNode() don't return null
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104 | if (currSubtreeCount < maxSubtreeCount) {
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105 |
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106 | var newNode = GetNewChildNode(currentNode, genotype, grammar, genotypeIndex, random);
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107 |
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108 | if ((currSubtreeCount + newNode.Symbol.MinimumArity) > maxSubtreeCount) {
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109 | // TODO: maybe check, if there is any node, which fits in the tree yet
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110 | currentNode.AddSubtree(GetRandomTerminalNode(currentNode, grammar, random));
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111 | } else {
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112 | currentNode.AddSubtree(newNode);
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113 | genotypeIndex++;
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114 | currSubtreeCount += newNode.Symbol.MinimumArity;
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115 |
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116 | while (newNode.Symbol.MinimumArity > newNode.SubtreeCount) {
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117 | MapDepthFirstRecursively(newNode, genotype,
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118 | grammar, maxSubtreeCount,
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119 | ref genotypeIndex, ref currSubtreeCount, random);
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120 | }
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121 | }
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122 |
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123 | } else {
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124 | while (currentNode.Symbol.MinimumArity > currentNode.SubtreeCount) {
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125 | var newNode = GetNewChildNode(currentNode, genotype, grammar, genotypeIndex, random);
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126 | currentNode.AddSubtree(newNode);
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127 | genotypeIndex++;
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128 | while (newNode.Symbol.MinimumArity > newNode.SubtreeCount) {
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129 | newNode.AddSubtree(GetRandomTerminalNode(newNode, grammar, random));
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130 | }
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131 | }
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132 | }
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133 | }
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134 |
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135 |
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136 | /// <summary>
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137 | /// Genotype-to-Phenotype mapper (iterative depth-first approach).
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138 | /// </summary>
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139 | /// <param name="startNode">first node of the tree with arity 1</param>
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140 | /// <param name="genotype">integer vector, which should be mapped to a tree</param>
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141 | /// <param name="grammar">grammar to determine the allowed child symbols for each node</param>
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142 | /// <param name="maxSubtreeCount">maximum allowed subtrees (= number of used genomes)</param>
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143 | /// <param name="random">random number generator</param>
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144 | private void MapDepthFirstIteratively(ISymbolicExpressionTreeNode startNode,
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145 | IntegerVector genotype,
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146 | ISymbolicExpressionGrammar grammar,
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147 | int maxSubtreeCount, IRandom random) {
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148 |
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149 | Stack<Tuple<ISymbolicExpressionTreeNode, int>> stack
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150 | = new Stack<Tuple<ISymbolicExpressionTreeNode, int>>(); // tuples of <node, arity>
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151 |
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152 | int genotypeIndex = 0;
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153 | int currSubtreeCount = 1;
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154 |
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155 | stack.Push(new Tuple<ISymbolicExpressionTreeNode, int>(startNode, 1));
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156 |
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157 | while ((currSubtreeCount < maxSubtreeCount) && (stack.Count > 0)) {
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158 |
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159 | // get next node from stack and re-push it, if this node still has unhandled subtrees ...
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160 | Tuple<ISymbolicExpressionTreeNode, int> current = stack.Pop();
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161 | if (current.Item2 > 1) {
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162 | stack.Push(new Tuple<ISymbolicExpressionTreeNode, int>(current.Item1, current.Item2 - 1));
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163 | }
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164 |
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165 | var newNode = GetNewChildNode(current.Item1, genotype, grammar, genotypeIndex, random);
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166 | int arity = SampleArity(random, newNode, maxSubtreeCount - currSubtreeCount);
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167 |
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168 | if (arity < 0) {
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169 | current.Item1.AddSubtree(GetRandomTerminalNode(current.Item1, grammar, random));
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170 | } else {
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171 | current.Item1.AddSubtree(newNode);
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172 | genotypeIndex++;
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173 | currSubtreeCount += arity;
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174 | if (arity > 0) {
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175 | // new node has subtrees so push it onto the stack
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176 | stack.Push(new Tuple<ISymbolicExpressionTreeNode, int>(newNode, arity));
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177 | }
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178 | }
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179 | }
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180 |
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181 | // maximum allowed subtree count was already reached, but there are still
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182 | // incomplete subtrees (non-terminal symbols) in the tree
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183 | // -> fill them with terminal symbols
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184 | while (stack.Count > 0) {
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185 | Tuple<ISymbolicExpressionTreeNode, int> current = stack.Pop();
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186 | if (current.Item2 > 1) {
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187 | stack.Push(new Tuple<ISymbolicExpressionTreeNode, int>(current.Item1, current.Item2 - 1));
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188 | }
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189 | current.Item1.AddSubtree(GetRandomTerminalNode(current.Item1, grammar, random));
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190 | }
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191 | }
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192 | }
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193 | } |
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