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source: trunk/sources/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/SymbolicDataAnalysisModelComplexityCalculator.cs @ 13300

Last change on this file since 13300 was 13300, checked in by gkronber, 7 years ago

#2175 made some changes while reviewing the code

File size: 3.5 KB
Line 
1#region License Information
2
3/* HeuristicLab
4 * Copyright (C) 2002-2015 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
5 *
6 * This file is part of HeuristicLab.
7 *
8 * HeuristicLab is free software: you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation, either version 3 of the License, or
11 * (at your option) any later version.
12 *
13 * HeuristicLab is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
20 */
21
22#endregion
23
24using System;
25using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
26
27namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
28  public static class SymbolicDataAnalysisModelComplexityCalculator {
29    public static double CalculateComplexity(ISymbolicExpressionTree tree) {
30      return CalculateComplexity(tree.Root);
31    }
32    public static double CalculateComplexity(ISymbolicExpressionTreeNode treeNode) {
33      var node = treeNode;
34      if (node.Symbol is ProgramRootSymbol) node = node.GetSubtree(0);
35      if (node.Symbol is StartSymbol) node = node.GetSubtree(0);
36
37      switch (OpCodes.MapSymbolToOpCode(node)) {
38        case OpCodes.Constant: {
39            return 1;
40          }
41        case OpCodes.Variable: {
42            return 2;
43          }
44        case OpCodes.Add:
45        case OpCodes.Sub: {
46            double complexity = 0;
47            for (int i = 0; i < node.SubtreeCount; i++) {
48              complexity += CalculateComplexity(node.GetSubtree(i));
49            }
50            return complexity;
51          }
52        case OpCodes.Mul:
53        case OpCodes.Div: {
54            double complexity = 1;
55            for (int i = 0; i < node.SubtreeCount; i++) {
56              var nodeComplexity = CalculateComplexity(node.GetSubtree(i));
57              complexity *= nodeComplexity + 1;
58            }
59            return complexity;
60          }
61        case OpCodes.Sin:
62        case OpCodes.Cos:
63        case OpCodes.Tan:
64        case OpCodes.Exp:
65        case OpCodes.Log: {
66            double complexity = CalculateComplexity(node.GetSubtree(0));
67            return Math.Pow(2.0, complexity);
68          }
69        case OpCodes.Square: {
70            double complexity = CalculateComplexity(node.GetSubtree(0));
71            return complexity * complexity;
72          }
73        case OpCodes.SquareRoot: {
74            double complexity = CalculateComplexity(node.GetSubtree(0));
75            return complexity * complexity * complexity;
76          }
77        case OpCodes.Power:         
78        case OpCodes.Root: {
79            double complexity = CalculateComplexity(node.GetSubtree(0));
80            var exponent = node.GetSubtree(1) as ConstantTreeNode;
81            if (exponent != null) {
82              double expVal = exponent.Value;
83              if (expVal < 0) expVal = Math.Abs(expVal);
84              if (expVal < 1) expVal = 1 / expVal;
85              return Math.Pow(complexity, Math.Round(expVal));
86            }
87
88            double expComplexity = CalculateComplexity(node.GetSubtree(1));
89            return Math.Pow(complexity, 2 * expComplexity);
90          }
91
92        default:
93          throw new NotSupportedException();
94      }
95    }
96  }
97}
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