1 | #region License Information
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2 | /* HeuristicLab
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3 | * Copyright (C) 2002-2018 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 HeuristicLab.Common;
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24 | using HeuristicLab.Core;
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25 | using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
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26 | using HeuristicLab.Optimization.Operators;
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27 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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28 |
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29 | namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
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30 | [StorableClass]
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31 | [Item("SymbolicExpressionTreeMaxCommonSubtreeSimilarityCalculator", "A similarity calculator based on the size of the maximum common subtree between two trees")]
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32 | public class SymbolicExpressionTreeMaxCommonSubtreeSimilarityCalculator : SolutionSimilarityCalculator {
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33 | [Storable]
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34 | private readonly SymbolicExpressionTreeNodeEqualityComparer comparer;
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35 | public bool MatchVariableWeights {
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36 | get { return comparer.MatchVariableWeights; }
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37 | set { comparer.MatchVariableWeights = value; }
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38 | }
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39 |
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40 | public bool MatchConstantValues {
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41 | get { return comparer.MatchConstantValues; }
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42 | set { comparer.MatchConstantValues = value; }
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43 | }
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44 |
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45 | protected override bool IsCommutative { get { return true; } }
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46 |
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47 | [StorableConstructor]
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48 | protected SymbolicExpressionTreeMaxCommonSubtreeSimilarityCalculator(bool deserializing) : base(deserializing) { }
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49 |
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50 | public override IDeepCloneable Clone(Cloner cloner) {
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51 | return new SymbolicExpressionTreeMaxCommonSubtreeSimilarityCalculator(this, cloner);
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52 | }
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53 |
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54 | protected SymbolicExpressionTreeMaxCommonSubtreeSimilarityCalculator(SymbolicExpressionTreeMaxCommonSubtreeSimilarityCalculator original, Cloner cloner)
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55 | : base(original, cloner) {
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56 | comparer = cloner.Clone(original.comparer);
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57 | }
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58 |
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59 | public SymbolicExpressionTreeMaxCommonSubtreeSimilarityCalculator() {
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60 | comparer = new SymbolicExpressionTreeNodeEqualityComparer {
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61 | MatchConstantValues = true,
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62 | MatchVariableNames = true,
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63 | MatchVariableWeights = true
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64 | };
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65 | }
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66 |
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67 | public SymbolicExpressionTreeMaxCommonSubtreeSimilarityCalculator(bool matchVariableWeights, bool matchConstantValues) {
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68 | comparer = new SymbolicExpressionTreeNodeEqualityComparer {
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69 | MatchConstantValues = matchConstantValues,
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70 | MatchVariableNames = true,
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71 | MatchVariableWeights = matchVariableWeights
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72 | };
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73 | }
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74 |
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75 | public double CalculateSimilarity(ISymbolicExpressionTree t1, ISymbolicExpressionTree t2) {
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76 | return MaxCommonSubtreeSimilarity(t1, t2, comparer);
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77 | }
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78 |
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79 | public override double CalculateSolutionSimilarity(IScope leftSolution, IScope rightSolution) {
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80 | var t1 = leftSolution.Variables[SolutionVariableName].Value as ISymbolicExpressionTree;
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81 | var t2 = rightSolution.Variables[SolutionVariableName].Value as ISymbolicExpressionTree;
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82 |
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83 | if (t1 == null || t2 == null)
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84 | throw new ArgumentException("Cannot calculate similarity when one of the arguments is null.");
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85 |
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86 | return MaxCommonSubtreeSimilarity(t1, t2, comparer);
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87 | }
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88 |
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89 | public static double MaxCommonSubtreeSimilarity(ISymbolicExpressionTree a, ISymbolicExpressionTree b, ISymbolicExpressionTreeNodeEqualityComparer comparer) {
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90 | int max = 0;
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91 | var rootA = a.Root.GetSubtree(0).GetSubtree(0);
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92 | var rootB = b.Root.GetSubtree(0).GetSubtree(0);
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93 | foreach (var aa in rootA.IterateNodesBreadth()) {
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94 | int lenA = aa.GetLength();
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95 | if (lenA <= max) continue;
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96 | foreach (var bb in rootB.IterateNodesBreadth()) {
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97 | int lenB = bb.GetLength();
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98 | if (lenB <= max) continue;
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99 | int matches = SymbolicExpressionTreeMatching.Match(aa, bb, comparer);
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100 | if (max < matches)
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101 | max = matches;
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102 | }
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103 | }
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104 | return 2.0 * max / (rootA.GetLength() + rootB.GetLength());
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105 | }
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106 | }
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107 | }
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