1 | using System;
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2 | using System.Collections.Generic;
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3 | using System.IO;
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4 | using System.Linq;
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5 | using HeuristicLab.Common;
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6 | using HeuristicLab.Core;
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7 | using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
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8 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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9 |
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10 | namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
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11 | public enum SimilarityLevel {
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12 | Exact, // everything is matched bit by bit (functions and terminals)
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13 | High, // symbols are matched. leaf node types are matched
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14 | Relaxed // only symbols are matched, leafs count as wildcards
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15 | }
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16 | [Item("SymbolicExpressionTreeNodeSimilarityComparer", "A comparison operator that checks node equality based on different similarity measures.")]
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17 | [StorableClass]
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18 | public class SymbolicExpressionTreeNodeSimilarityComparer : Item, ISymbolicExpressionTreeNodeComparer {
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19 | [StorableConstructor]
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20 | private SymbolicExpressionTreeNodeSimilarityComparer(bool deserializing) : base(deserializing) { }
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21 | private SymbolicExpressionTreeNodeSimilarityComparer(SymbolicExpressionTreeNodeSimilarityComparer original, Cloner cloner) : base(original, cloner) { }
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22 | public override IDeepCloneable Clone(Cloner cloner) { return new SymbolicExpressionTreeNodeSimilarityComparer(this, cloner); }
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23 |
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24 | private SimilarityLevel similarityLevel;
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25 | public SimilarityLevel SimilarityLevel {
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26 | get { return similarityLevel; }
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27 | set { similarityLevel = value; }
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28 | }
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29 |
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30 | public SymbolicExpressionTreeNodeSimilarityComparer() {
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31 | this.similarityLevel = SimilarityLevel.Exact;
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32 | }
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33 |
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34 | public SymbolicExpressionTreeNodeSimilarityComparer(SimilarityLevel similarityLevel) {
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35 | this.similarityLevel = similarityLevel;
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36 | }
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37 |
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38 | public int GetHashCode(ISymbolicExpressionTreeNode n) {
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39 | return n.ToString().ToLower().GetHashCode();
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40 | }
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41 |
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42 | public bool Equals(ISymbolicExpressionTreeNode a, ISymbolicExpressionTreeNode b) {
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43 | var ca = a as ConstantTreeNode;
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44 | var cb = b as ConstantTreeNode;
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45 | var va = a as VariableTreeNode;
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46 | var vb = b as VariableTreeNode;
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47 |
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48 | var aIsConstant = ca != null;
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49 | var aIsVariable = va != null;
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50 | var bIsConstant = cb != null;
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51 | var bIsVariable = vb != null;
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52 | var aIsFunction = (!(aIsConstant | aIsVariable));
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53 | var bIsFunction = (!(bIsConstant | bIsVariable));
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54 |
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55 | if (aIsFunction)
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56 | return bIsFunction && a.Symbol.Name.Equals(b.Symbol.Name);
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57 | if (bIsFunction) // one is function and the other is not, return false
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58 | return false;
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59 |
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60 | switch (similarityLevel) {
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61 | case (SimilarityLevel.Exact):
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62 | if (aIsConstant & bIsConstant)
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63 | return ca.Value.Equals(cb.Value);
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64 | if (aIsVariable & bIsVariable)
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65 | return va.Weight.Equals(vb.Weight);
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66 | return false;
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67 | case (SimilarityLevel.High):
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68 | return ((aIsConstant & bIsConstant) || (aIsVariable & bIsVariable));
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69 | case (SimilarityLevel.Relaxed):
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70 | return true;
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71 | default:
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72 | return false;
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73 | }
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74 | }
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75 |
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76 | public static bool ExactlySimilar(ISymbolicExpressionTreeNode a, ISymbolicExpressionTreeNode b) {
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77 | return Similar(a, b, SimilarityLevel.Exact);
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78 | }
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79 |
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80 | public static bool Similar(ISymbolicExpressionTreeNode a, ISymbolicExpressionTreeNode b, SimilarityLevel level) {
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81 | var comp = new SymbolicExpressionTreeNodeSimilarityComparer(level);
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82 | return comp.Equals(a, b);
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83 | }
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84 | }
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85 |
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86 | public class SymbolicExpressionTreeNodeOrderingComparer : IComparer<ISymbolicExpressionTreeNode> {
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87 | public int Compare(ISymbolicExpressionTreeNode a, ISymbolicExpressionTreeNode b) {
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88 | var ca = a as ConstantTreeNode;
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89 | var cb = b as ConstantTreeNode;
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90 | var va = a as VariableTreeNode;
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91 | var vb = b as VariableTreeNode;
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92 |
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93 | var aIsConstant = ca != null;
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94 | var aIsVariable = va != null;
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95 | var bIsConstant = cb != null;
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96 | var bIsVariable = vb != null;
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97 | var aIsFunction = (!(aIsConstant | aIsVariable));
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98 | var bIsFunction = (!(bIsConstant | bIsVariable));
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99 |
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100 | if (aIsFunction)
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101 | return bIsFunction ? a.Symbol.Name.CompareTo(b.Symbol.Name) : -1;
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102 | if (bIsFunction) // a is Constant or Variables
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103 | return 1;
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104 | if (aIsVariable)
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105 | return bIsVariable ? va.Weight.CompareTo(vb.Weight) : -1;
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106 | return
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107 | bIsVariable ? 1 : ca.Value.CompareTo(cb.Value);
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108 | }
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109 | }
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110 |
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111 | // tree equality
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112 | public class SymbolicExpressionTreeEqualityComparer : IEqualityComparer<ISymbolicExpressionTree> {
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113 | public bool Equals(ISymbolicExpressionTree a, ISymbolicExpressionTree b) {
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114 | return SymbolicExpressionTreeMatching.FindMatch(a, b, similarityLevel) == 0;
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115 | }
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116 |
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117 | public int GetHashCode(ISymbolicExpressionTree tree) {
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118 | return (tree.Length << 8) % 12345;
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119 | }
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120 |
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121 | private SimilarityLevel similarityLevel;
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122 | public void SetComparisonMode(SimilarityLevel simLevel) {
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123 | similarityLevel = simLevel;
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124 | }
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125 | }
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126 |
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127 | public static class SymbolicExpressionTreeMatching {
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128 | public static bool IsSimilarTo(this ISymbolicExpressionTree t1, ISymbolicExpressionTree t2, SimilarityLevel mode) {
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129 | return FindMatch(t1, t2, mode) == 0;
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130 | }
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131 |
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132 | public static bool IsSimilarTo(this ISymbolicExpressionTreeNode t1, ISymbolicExpressionTreeNode t2, SimilarityLevel mode) {
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133 | return FindMatch(t1, t2, mode) == 0;
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134 | }
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135 |
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136 | public static bool ContainsFragment(this ISymbolicExpressionTree tree, ISymbolicExpressionTreeNode fragment, SimilarityLevel mode) {
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137 | var matches = FindMatches(tree, fragment, mode);
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138 | return matches.Count > 0;
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139 | }
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140 |
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141 | public static void SortSubtrees(this ISymbolicExpressionTree tree) {
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142 | SortSubtrees(tree.Root);
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143 | }
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144 |
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145 | public static void SortSubtrees(this ISymbolicExpressionTreeNode node) {
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146 | if (node.SubtreeCount == 0) return;
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147 | var subtrees = node.Subtrees as List<ISymbolicExpressionTreeNode>;
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148 | if (subtrees == null) return;
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149 | var comparer = new SymbolicExpressionTreeNodeOrderingComparer();
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150 | subtrees.Sort(comparer);
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151 | foreach (var subtree in subtrees)
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152 | subtree.SortSubtrees();
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153 | }
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154 |
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155 | // return child that is the same as node
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156 | public static ISymbolicExpressionTreeNode FindChild(this ISymbolicExpressionTreeNode parent, ISymbolicExpressionTreeNode node) {
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157 | var subtrees = parent.Subtrees as List<ISymbolicExpressionTreeNode>;
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158 | var comparer = new SymbolicExpressionTreeNodeSimilarityComparer(SimilarityLevel.Exact);
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159 | return subtrees.Find(x => comparer.Equals(x, node));
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160 | }
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161 |
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162 | public static int FindMatch(ISymbolicExpressionTree a, ISymbolicExpressionTree b, SimilarityLevel similarityLevel) {
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163 | var nodesA = a.IterateNodesPostfix() as List<ISymbolicExpressionTreeNode>;
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164 | var nodesB = b.IterateNodesPostfix() as List<ISymbolicExpressionTreeNode>;
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165 | return FindMatch(nodesA, nodesB, similarityLevel);
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166 | }
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167 |
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168 | public static int FindMatch(ISymbolicExpressionTreeNode a, ISymbolicExpressionTreeNode b, SimilarityLevel similarityLevel) {
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169 | var nodesA = a.IterateNodesPostfix() as List<ISymbolicExpressionTreeNode>;
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170 | var nodesB = b.IterateNodesPostfix() as List<ISymbolicExpressionTreeNode>;
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171 | return FindMatch(nodesA, nodesB, similarityLevel);
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172 | }
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173 |
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174 | // returns the index in the sequence 'seq', where pattern 'pat' is matched, or -1 for no match
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175 | // -1 means no match, 0 means perfect match (the sequences overlap, hence the match index is 0)
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176 | public static int FindMatch(List<ISymbolicExpressionTreeNode> seq, List<ISymbolicExpressionTreeNode> pat, SimilarityLevel similarityLevel) {
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177 | int patlen = pat.Count;
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178 | int seqlen = seq.Count;
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179 | if (patlen == 0 || seqlen == 0) return -1;
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180 | var comparer = new SymbolicExpressionTreeNodeSimilarityComparer(similarityLevel);
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181 | if (patlen == seqlen) return seq.SequenceEqual(pat, comparer) ? 0 : -1;
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182 | for (int i = patlen; i <= seqlen; ++i) {
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183 | if (comparer.Equals(seq[i - 1], pat.Last())) // first check if last element is a match
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184 | if (seq.Skip(i - patlen).Take(patlen).SequenceEqual(pat, comparer)) // then check the whole sequence
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185 | return i - patlen;
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186 | }
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187 | return -1;
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188 | }
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189 |
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190 | public static List<ISymbolicExpressionTreeNode> FindMatches(ISymbolicExpressionTree tree, ISymbolicExpressionTreeNode fragment, SimilarityLevel similarityLevel) {
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191 | var comp = new SymbolicExpressionTreeNodeSimilarityComparer(similarityLevel);
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192 | return FindMatches(tree.Root, fragment, comp);
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193 | }
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194 |
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195 | public static List<ISymbolicExpressionTreeNode>
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196 | FindMatches(ISymbolicExpressionTreeNode root, ISymbolicExpressionTreeNode fragment, SymbolicExpressionTreeNodeSimilarityComparer comp) {
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197 | var matches = new List<ISymbolicExpressionTreeNode>();
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198 | root.ForEachNodePostfix(node => {
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199 | if (Match(node, fragment, comp) == fragment.GetLength()) matches.Add(node);
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200 | });
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201 | return matches;
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202 | }
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203 |
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204 | ///<summary>
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205 | /// Finds the longest common subsequence in quadratic time and linear space
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206 | /// Variant of:
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207 | /// D . S. Hirschberg. A linear space algorithm for or computing maximal common subsequences. 1975.
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208 | /// http://dl.acm.org/citation.cfm?id=360861
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209 | /// </summary>
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210 | /// <returns>Number of pairs that were matched</returns>
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211 | public static int
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212 | Match(ISymbolicExpressionTreeNode a, ISymbolicExpressionTreeNode b, SymbolicExpressionTreeNodeSimilarityComparer comp) {
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213 | if (!comp.Equals(a, b))
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214 | return 0;
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215 |
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216 | int m = a.SubtreeCount;
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217 | int n = b.SubtreeCount;
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218 | if (m == 0 || n == 0) return 1;
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219 |
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220 | var matrix = new int[m + 1, n + 1];
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221 | for (int i = 1; i <= m; ++i)
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222 | for (int j = 1; j <= n; ++j) {
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223 | var ai = a.GetSubtree(i - 1);
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224 | var bj = b.GetSubtree(j - 1);
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225 | int match = Match(ai, bj, comp);
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226 | matrix[i, j] = Math.Max(Math.Max(matrix[i, j - 1], matrix[i - 1, j]), matrix[i - 1, j - 1] + match);
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227 | }
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228 | return matrix[m, n] + 1;
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229 | }
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230 |
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231 | public static int
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232 | LCS(ISymbolicExpressionTreeNode a, ISymbolicExpressionTreeNode b, SymbolicExpressionTreeNodeSimilarityComparer comp) {
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233 | var nodesA = a.IterateNodesPrefix().ToList();
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234 | var nodesB = b.IterateNodesPrefix().ToList();
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235 | int m = nodesA.Count;
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236 | int n = nodesB.Count;
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237 | var matrix = new int[m + 1, n + 1];
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238 | for (int i = 1; i <= m; ++i) {
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239 | for (int j = 1; j <= n; ++j) {
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240 | int w = comp.Equals(a, b) ? 1 : 0;
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241 | matrix[i, j] = Math.Max(Math.Max(matrix[i, j - 1], matrix[i - 1, j]), matrix[i - 1, j - 1] + w);
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242 | }
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243 | }
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244 | return matrix[m, n];
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245 | }
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246 |
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247 | public static void RenderTree(TextWriter writer, ISymbolicExpressionTree tree) {
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248 | RenderNode(writer, tree.Root, string.Empty);
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249 | }
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250 |
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251 | public static void RenderNode(TextWriter writer, ISymbolicExpressionTreeNode node, string prefix) {
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252 | string label;
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253 | if (node is VariableTreeNode) {
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254 | var variable = node as VariableTreeNode;
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255 | label = string.Concat(string.Format("{0:0.000}", variable.Weight), '·', variable.VariableName);
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256 | } else if (node is ConstantTreeNode) {
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257 | var constant = node as ConstantTreeNode;
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258 | label = string.Format("{0:0.000}", constant.Value);
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259 | } else {
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260 | label = node.Symbol.ToString();
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261 | }
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262 |
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263 | writer.Write(label);
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264 | if (node.SubtreeCount > 0) {
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265 | char connector, extender = ' ';
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266 | var padding = prefix + new string(' ', label.Length);
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267 | for (int i = 0; i != node.SubtreeCount; ++i) {
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268 | if (i == 0) {
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269 | if (node.SubtreeCount > 1) {
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270 | connector = RenderChars.JunctionDown;
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271 | extender = RenderChars.VerticalLine;
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272 | } else {
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273 | connector = RenderChars.HorizontalLine;
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274 | extender = ' ';
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275 | }
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276 | } else {
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277 | writer.Write(padding);
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278 | if (i == node.SubtreeCount - 1) {
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279 | connector = RenderChars.CornerRight;
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280 | extender = ' ';
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281 | } else {
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282 | connector = RenderChars.JunctionRight;
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283 | extender = RenderChars.VerticalLine;
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284 | }
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285 | }
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286 | writer.Write(string.Concat(connector, RenderChars.HorizontalLine));
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287 | var newPrefix = string.Concat(padding, extender, ' ');
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288 | RenderNode(writer, node.GetSubtree(i), newPrefix);
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289 | }
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290 | } else
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291 | writer.WriteLine();
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292 | }
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293 | }
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294 |
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295 | // helper class providing characters for displaying a tree in the console
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296 | public static class RenderChars {
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297 | public const char JunctionDown = '┬';
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298 | public const char HorizontalLine = '─';
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299 | public const char VerticalLine = '│';
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300 | public const char JunctionRight = '├';
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301 | public const char CornerRight = '└';
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302 | }
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303 | }
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