[11486] | 1 | #region License Information
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| 2 | /* HeuristicLab
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[17193] | 3 | * Copyright (C) Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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[11486] | 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 HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
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[16676] | 24 | using HEAL.Attic;
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[10562] | 25 |
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| 26 | namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
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[16676] | 27 | [StorableType("eabf848e-d10c-499e-8c48-c771232ede0e")]
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[10562] | 28 | // this comparer considers that a < b if the type of a is "greater" than the type of b, for example:
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| 29 | // - A function node is "greater" than a terminal node
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| 30 | // - A variable terminal is "greater" than a constant terminal
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| 31 | // - used for bringing subtrees to a "canonical" form when the operation allows reordering of arguments
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| 32 | public class SymbolicExpressionTreeNodeComparer : ISymbolicExpressionTreeNodeComparer {
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[11910] | 33 | public static int CompareNodes(ISymbolicExpressionTreeNode a, ISymbolicExpressionTreeNode b) {
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[11486] | 34 | var ta = a as SymbolicExpressionTreeTerminalNode;
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| 35 | var tb = b as SymbolicExpressionTreeTerminalNode;
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| 36 |
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| 37 | if (ta == null)
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| 38 | return tb == null ? String.CompareOrdinal(a.Symbol.Name, b.Symbol.Name) : -1;
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| 39 |
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| 40 | if (tb == null)
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| 41 | return 1;
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| 42 |
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| 43 | // at this point we know a and b are both terminals
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[10562] | 44 | var va = a as VariableTreeNode;
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[11486] | 45 | var vb = b as VariableTreeNode;
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| 46 |
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| 47 | if (va != null)
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| 48 | return vb == null ? -1 : CompareVariables(va, vb);
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| 49 |
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| 50 | if (vb != null)
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| 51 | return 1;
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| 52 |
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| 53 | // at this point we know a and b are not variables
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| 54 | var ca = a as ConstantTreeNode;
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| 55 | var cb = b as ConstantTreeNode;
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| 56 |
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| 57 | if (ca != null && cb != null)
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| 58 | return ca.Value.CompareTo(cb.Value);
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| 59 |
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| 60 | // for other unknown terminal types, compare strings
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| 61 | return string.CompareOrdinal(a.ToString(), b.ToString());
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[10562] | 62 | }
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[11486] | 63 |
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| 64 | private static int CompareVariables(VariableTreeNode a, VariableTreeNode b) {
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| 65 | int result = string.CompareOrdinal(a.VariableName, b.VariableName);
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| 66 | return result == 0 ? a.Weight.CompareTo(b.Weight) : result;
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| 67 | }
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[11894] | 68 |
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[11910] | 69 | public int Compare(ISymbolicExpressionTreeNode x, ISymbolicExpressionTreeNode y) {
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| 70 | return CompareNodes(x, y);
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[11894] | 71 | }
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[10562] | 72 | }
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[11486] | 73 |
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[10562] | 74 | }
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