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source: branches/HeuristicLab.BottomUpTreeDistance/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/SimilarityCalculators/MaxCommonSubtreeSimilarityCalculator.cs @ 11230

Last change on this file since 11230 was 11230, checked in by bburlacu, 10 years ago

#2215: Fixed bug in MaxCommonSubtreeSimilarityCalculator and added performance unit test.

File size: 3.2 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2014 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
4 *
5 * This file is part of HeuristicLab.
6 *
7 * HeuristicLab is free software: you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation, either version 3 of the License, or
10 * (at your option) any later version.
11 *
12 * HeuristicLab is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
19 */
20#endregion
21
22using System;
23using HeuristicLab.Common;
24using HeuristicLab.Core;
25using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
26using HeuristicLab.Optimization.Operators;
27using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
28
29namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
30  [StorableClass]
31  [Item("MaxCommonSubtreeSimilarityCalculator", "A similarity calculator based on the size of the maximum common subtree between two trees")]
32  public class MaxCommonSubtreeSimilarityCalculator : SingleObjectiveSolutionSimilarityCalculator {
33    public MaxCommonSubtreeSimilarityCalculator() { }
34
35    protected MaxCommonSubtreeSimilarityCalculator(MaxCommonSubtreeSimilarityCalculator original, Cloner cloner)
36      : base(original, cloner) {
37    }
38
39    public override IDeepCloneable Clone(Cloner cloner) {
40      return new MaxCommonSubtreeSimilarityCalculator(this, cloner);
41    }
42
43    public override double CalculateSolutionSimilarity(IScope leftSolution, IScope rightSolution) {
44      var t1 = leftSolution.Variables[SolutionVariableName].Value as ISymbolicExpressionTree;
45      var t2 = rightSolution.Variables[SolutionVariableName].Value as ISymbolicExpressionTree;
46
47      if (t1 == null || t2 == null)
48        throw new ArgumentException("Cannot calculate similarity when one of the arguments is null.");
49      var comparer = new SymbolicExpressionTreeNodeSimilarityComparer {
50        MatchConstantValues = true,
51        MatchVariableNames = true,
52        MatchVariableWeights = true
53      };
54
55      return MaxCommonSubtreeSimilarity(t1, t2, comparer);
56    }
57
58    public static double MaxCommonSubtreeSimilarity(ISymbolicExpressionTree a, ISymbolicExpressionTree b, SymbolicExpressionTreeNodeSimilarityComparer comparer) {
59      int max = 0;
60      var rootA = a.Root.GetSubtree(0).GetSubtree(0);
61      var rootB = b.Root.GetSubtree(0).GetSubtree(0);
62      foreach (var aa in rootA.IterateNodesBreadth()) {
63        int lenA = aa.GetLength();
64        if (lenA <= max) continue;
65        foreach (var bb in rootB.IterateNodesBreadth()) {
66          int lenB = bb.GetLength();
67          if (lenB <= max) continue;
68          int matches = SymbolicExpressionTreeMatching.Match(aa, bb, comparer);
69          if (matches == lenB && max < matches)
70            max = matches;
71        }
72      }
73      return 2.0 * max / (rootA.GetLength() + rootB.GetLength());
74    }
75  }
76}
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