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source: branches/RemoveBackwardsCompatibility/HeuristicLab.Problems.GrammaticalEvolution/3.3/Mappers/DepthFirstMapper.cs

Last change on this file was 12012, checked in by ascheibe, 10 years ago

#2212 merged r12008, r12009, r12010 back into trunk

File size: 5.5 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2015 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 * Author: Sabine Winkler
21 */
22
23#endregion
24
25using System;
26using System.Collections.Generic;
27using HeuristicLab.Common;
28using HeuristicLab.Core;
29using HeuristicLab.Data;
30using HeuristicLab.Encodings.IntegerVectorEncoding;
31using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
32using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
33
34namespace HeuristicLab.Problems.GrammaticalEvolution {
35  /// <summary>
36  /// DepthFirstMapper
37  /// </summary>
38  [Item("DepthFirstMapper", "Resolves the non-terminal symbols of the resulting phenotypic syntax tree in a depth-first manner.")]
39  [StorableClass]
40  public class DepthFirstMapper : GenotypeToPhenotypeMapper {
41
42    [StorableConstructor]
43    protected DepthFirstMapper(bool deserializing) : base(deserializing) { }
44    protected DepthFirstMapper(DepthFirstMapper original, Cloner cloner) : base(original, cloner) { }
45    public DepthFirstMapper() : base() { }
46
47    public override IDeepCloneable Clone(Cloner cloner) {
48      return new DepthFirstMapper(this, cloner);
49    }
50
51
52    /// <summary>
53    /// Maps a genotype (an integer vector) to a phenotype (a symbolic expression tree).
54    /// Depth-first approach.
55    /// </summary>
56    /// <param name="random">random number generator</param>
57    /// <param name="bounds">only used for PIGEMapper (ignore here)</param>
58    /// <param name="length">only used for PIGEMapper (ignore here)</param>
59    /// <param name="grammar">grammar definition</param>
60    /// <param name="genotype">integer vector, which should be mapped to a tree</param>
61    /// <returns>phenotype (a symbolic expression tree)</returns>
62    public override SymbolicExpressionTree Map(IRandom random, IntMatrix bounds, int length,
63                                               ISymbolicExpressionGrammar grammar,
64                                               IntegerVector genotype) {
65
66      SymbolicExpressionTree tree = new SymbolicExpressionTree();
67      var rootNode = (SymbolicExpressionTreeTopLevelNode)grammar.ProgramRootSymbol.CreateTreeNode();
68      if (rootNode.HasLocalParameters) rootNode.ResetLocalParameters(random);
69      var startNode = (SymbolicExpressionTreeTopLevelNode)grammar.StartSymbol.CreateTreeNode();
70      if (startNode.HasLocalParameters) startNode.ResetLocalParameters(random);
71      rootNode.AddSubtree(startNode);
72      tree.Root = rootNode;
73
74      MapDepthFirstIteratively(startNode, genotype, grammar,
75                               genotype.Length, random);
76      return tree;
77    }
78
79
80    /// <summary>
81    /// Genotype-to-Phenotype mapper (iterative depth-first approach, by using a stack -> LIFO).
82    /// </summary>
83    /// <param name="startNode">first node of the tree with arity 1</param>
84    /// <param name="genotype">integer vector, which should be mapped to a tree</param>
85    /// <param name="grammar">grammar to determine the allowed child symbols for each node</param>
86    /// <param name="maxSubtreeCount">maximum allowed subtrees (= number of used genomes)</param>
87    /// <param name="random">random number generator</param>
88    private void MapDepthFirstIteratively(ISymbolicExpressionTreeNode startNode,
89                                          IntegerVector genotype,
90                                          ISymbolicExpressionGrammar grammar,
91                                          int maxSubtreeCount, IRandom random) {
92
93      Stack<Tuple<ISymbolicExpressionTreeNode, int>> stack
94        = new Stack<Tuple<ISymbolicExpressionTreeNode, int>>(); // tuples of <node, arity>
95
96      int genotypeIndex = 0;
97      stack.Push(new Tuple<ISymbolicExpressionTreeNode, int>(startNode, 1));
98
99      while (stack.Count > 0) {
100
101        // get next node from stack and re-push it, if this node still has unhandled subtrees ...
102        Tuple<ISymbolicExpressionTreeNode, int> current = stack.Pop();
103        if (current.Item2 > 1) {
104          stack.Push(new Tuple<ISymbolicExpressionTreeNode, int>(current.Item1, current.Item2 - 1));
105        }
106
107        if (genotypeIndex >= maxSubtreeCount) {
108          // if all genomes were used, only add terminal nodes to the remaining subtrees
109          current.Item1.AddSubtree(GetRandomTerminalNode(current.Item1, grammar, random));
110        } else {
111          var newNode = GetNewChildNode(current.Item1, genotype, grammar, genotypeIndex, random);
112          int arity = SampleArity(random, newNode, grammar);
113
114          current.Item1.AddSubtree(newNode);
115          genotypeIndex++;
116          if (arity > 0) {
117            // new node has subtrees so push it onto the stack
118            stack.Push(new Tuple<ISymbolicExpressionTreeNode, int>(newNode, arity));
119          }
120        }
121      }
122    }
123  }
124}
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