[11239] | 1 | #region License Information
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| 2 | /* HeuristicLab
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| 3 | * Copyright (C) 2002-2014 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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[10562] | 23 | using System.Collections.Generic;
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| 24 | using System.Linq;
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| 25 | using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
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| 26 | //using HeuristicLab.EvolutionTracking;
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| 27 |
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| 28 | namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
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| 29 | public static class SymbolicExpressionTreeMatching {
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| 30 | public static bool ContainsSubtree(this ISymbolicExpressionTreeNode root, ISymbolicExpressionTreeNode subtree, SymbolicExpressionTreeNodeSimilarityComparer comparer) {
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| 31 | return FindMatches(root, subtree, comparer).Any();
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| 32 | }
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| 33 | public static IEnumerable<ISymbolicExpressionTreeNode> FindMatches(ISymbolicExpressionTree tree, ISymbolicExpressionTreeNode subtree, SymbolicExpressionTreeNodeSimilarityComparer comparer) {
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| 34 | return FindMatches(tree.Root, subtree, comparer);
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| 35 | }
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| 36 |
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| 37 | public static IEnumerable<ISymbolicExpressionTreeNode> FindMatches(ISymbolicExpressionTreeNode root, ISymbolicExpressionTreeNode subtree, SymbolicExpressionTreeNodeSimilarityComparer comp) {
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| 38 | var fragmentLength = subtree.GetLength();
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| 39 | // below, we use ">=" for Match(n, subtree, comp) >= fragmentLength because in case of relaxed conditions,
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| 40 | // we can have multiple matches of the same node
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| 41 |
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| 42 | return root.IterateNodesBreadth().Where(n => n.GetLength() >= fragmentLength && Match(n, subtree, comp) == fragmentLength);
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| 43 | }
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| 44 |
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| 45 | ///<summary>
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| 46 | /// Finds the longest common subsequence in quadratic time and linear space
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| 47 | /// Variant of:
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| 48 | /// D. S. Hirschberg. A linear space algorithm for or computing maximal common subsequences. 1975.
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| 49 | /// http://dl.acm.org/citation.cfm?id=360861
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| 50 | /// </summary>
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| 51 | /// <returns>Number of pairs that were matched</returns>
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[11239] | 52 | public static int Match(ISymbolicExpressionTreeNode a, ISymbolicExpressionTreeNode b, ISymbolicExpressionTreeNodeSimilarityComparer comp) {
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[10562] | 53 | if (!comp.Equals(a, b)) return 0;
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| 54 | int m = a.SubtreeCount;
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| 55 | int n = b.SubtreeCount;
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| 56 | if (m == 0 || n == 0) return 1;
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| 57 | var matrix = new int[m + 1, n + 1];
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| 58 | for (int i = 1; i <= m; ++i) {
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| 59 | var ai = a.GetSubtree(i - 1);
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| 60 | for (int j = 1; j <= n; ++j) {
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| 61 | var bj = b.GetSubtree(j - 1);
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| 62 | int match = Match(ai, bj, comp);
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| 63 | 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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| 64 | }
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| 65 | }
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| 66 | return matrix[m, n] + 1;
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| 67 | }
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| 68 | }
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| 69 | }
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