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source: trunk/sources/HeuristicLab.Encodings.SymbolicExpressionTreeEncoding/3.4/Creators/RampedHalfAndHalfTreeCreator.cs @ 7172

Last change on this file since 7172 was 7034, checked in by bburlacu, 13 years ago

#1654: Fixed bug in the RampedHalfAndHalfTreeCreator

File size: 7.3 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2011 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 System.Collections.Generic;
24using System.ComponentModel;
25using System.Linq;
26using HeuristicLab.Common;
27using HeuristicLab.Core;
28using HeuristicLab.Data;
29using HeuristicLab.Parameters;
30using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
31using HeuristicLab.PluginInfrastructure;
32
33namespace HeuristicLab.Encodings.SymbolicExpressionTreeEncoding {
34  [NonDiscoverableType]
35  [StorableClass]
36  [Item("RampedHalfAndHalfTreeCreator", "An operator that creates new symbolic expression trees in an alternate way: half the trees are created usign the 'Grow' method while the other half are created using the 'Full' method")]
37  public class RampedHalfAndHalfTreeCreator : SymbolicExpressionTreeCreator,
38                                 ISymbolicExpressionTreeSizeConstraintOperator,
39                                 ISymbolicExpressionTreeGrammarBasedOperator {
40    private const string MaximumSymbolicExpressionTreeLengthParameterName = "MaximumSymbolicExpressionTreeLength";
41    private const string MaximumSymbolicExpressionTreeDepthParameterName = "MaximumSymbolicExpressionTreeDepth";
42    private const string SymbolicExpressionTreeGrammarParameterName = "SymbolicExpressionTreeGrammar";
43    private const string ClonedSymbolicExpressionTreeGrammarParameterName = "ClonedSymbolicExpressionTreeGrammar";
44
45    #region Parameter Properties
46    public IValueLookupParameter<IntValue> MaximumSymbolicExpressionTreeLengthParameter {
47      get { return (IValueLookupParameter<IntValue>)Parameters[MaximumSymbolicExpressionTreeLengthParameterName]; }
48    }
49
50    public IValueLookupParameter<IntValue> MaximumSymbolicExpressionTreeDepthParameter {
51      get { return (IValueLookupParameter<IntValue>)Parameters[MaximumSymbolicExpressionTreeDepthParameterName]; }
52    }
53
54    public IValueLookupParameter<ISymbolicExpressionGrammar> SymbolicExpressionTreeGrammarParameter {
55      get {
56        return
57            (IValueLookupParameter<ISymbolicExpressionGrammar>)
58            Parameters[SymbolicExpressionTreeGrammarParameterName];
59      }
60    }
61
62    public ILookupParameter<ISymbolicExpressionGrammar> ClonedSymbolicExpressionTreeGrammarParameter {
63      get {
64        return
65            (ILookupParameter<ISymbolicExpressionGrammar>)
66            Parameters[ClonedSymbolicExpressionTreeGrammarParameterName];
67      }
68    }
69
70    #endregion
71    #region Properties
72    public IntValue MaximumSymbolicExpressionTreeDepth {
73      get { return MaximumSymbolicExpressionTreeDepthParameter.ActualValue; }
74    }
75
76    public IntValue MaximumSymbolicExpressionTreeLength {
77      get { return MaximumSymbolicExpressionTreeLengthParameter.ActualValue; }
78    }
79
80    public ISymbolicExpressionGrammar SymbolicExpressionTreeGrammar {
81      get { return ClonedSymbolicExpressionTreeGrammarParameter.ActualValue; }
82    }
83    #endregion
84
85    [StorableConstructor]
86    protected RampedHalfAndHalfTreeCreator(bool deserializing) : base(deserializing) { }
87    protected RampedHalfAndHalfTreeCreator(RampedHalfAndHalfTreeCreator original, Cloner cloner) : base(original, cloner) { }
88
89    public RampedHalfAndHalfTreeCreator()
90      : base() {
91      Parameters.Add(new ValueLookupParameter<IntValue>(MaximumSymbolicExpressionTreeLengthParameterName, "The maximal length (number of nodes) of the symbolic expression tree."));
92      Parameters.Add(new ValueLookupParameter<IntValue>(MaximumSymbolicExpressionTreeDepthParameterName, "The maximal depth of the symbolic expression tree (a tree with one node has depth = 0)."));
93      Parameters.Add(new ValueLookupParameter<ISymbolicExpressionGrammar>(SymbolicExpressionTreeGrammarParameterName, "The tree grammar that defines the correct syntax of symbolic expression trees that should be created."));
94      Parameters.Add(new LookupParameter<ISymbolicExpressionGrammar>(ClonedSymbolicExpressionTreeGrammarParameterName, "An immutable clone of the concrete grammar that is actually used to create and manipulate trees."));
95    }
96
97    public override IDeepCloneable Clone(Cloner cloner) {
98      return new RampedHalfAndHalfTreeCreator(this, cloner);
99    }
100
101    public override IOperation Apply() {
102      if (ClonedSymbolicExpressionTreeGrammarParameter.ActualValue == null) {
103        SymbolicExpressionTreeGrammarParameter.ActualValue.ReadOnly = true;
104        IScope globalScope = ExecutionContext.Scope;
105        while (globalScope.Parent != null)
106          globalScope = globalScope.Parent;
107
108        globalScope.Variables.Add(new Variable(ClonedSymbolicExpressionTreeGrammarParameterName, (ISymbolicExpressionGrammar)SymbolicExpressionTreeGrammarParameter.ActualValue.Clone()));
109      }
110      return base.Apply();
111    }
112
113    protected override ISymbolicExpressionTree Create(IRandom random) {
114      return Create(random, SymbolicExpressionTreeGrammar, MaximumSymbolicExpressionTreeLength.Value, MaximumSymbolicExpressionTreeDepth.Value);
115    }
116
117    public override ISymbolicExpressionTree CreateTree(IRandom random, ISymbolicExpressionGrammar grammar, int maxTreeLength, int maxTreeDepth) {
118      return Create(random, grammar, maxTreeLength, maxTreeDepth);
119    }
120
121    /// <summary>
122    /// Create a symbolic expression tree using 'RampedHalfAndHalf' strategy.
123    /// Half the trees are created with the 'Grow' method, and the other half are created with the 'Full' method.
124    /// </summary>
125    /// <param name="random">Random generator</param>
126    /// <param name="grammar">Available tree grammar</param>
127    /// <param name="maxTreeDepth">Maximum tree depth</param>
128    /// <returns></returns>
129    public static ISymbolicExpressionTree Create(IRandom random, ISymbolicExpressionGrammar grammar, int maxTreeLength, int maxTreeDepth) {
130      var tree = new SymbolicExpressionTree();
131      var rootNode = (SymbolicExpressionTreeTopLevelNode)grammar.ProgramRootSymbol.CreateTreeNode();
132      if (rootNode.HasLocalParameters) rootNode.ResetLocalParameters(random);
133      rootNode.SetGrammar(new SymbolicExpressionTreeGrammar(grammar));
134
135      var startNode = (SymbolicExpressionTreeTopLevelNode)grammar.StartSymbol.CreateTreeNode();
136      startNode.SetGrammar(new SymbolicExpressionTreeGrammar(grammar));
137      if (startNode.HasLocalParameters) startNode.ResetLocalParameters(random);
138
139      rootNode.AddSubtree(startNode);
140
141      double p = random.NextDouble();
142
143      if (p < 0.5)
144        GrowTreeCreator.Grow(random, startNode, maxTreeDepth - 2);
145      else
146        FullTreeCreator.Grow(random, startNode, maxTreeDepth - 2);
147
148      tree.Root = rootNode;
149      return tree;
150    }
151  }
152}
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