source: trunk/HeuristicLab.Encodings.SymbolicExpressionTreeEncoding/3.4/Creators/RampedHalfAndHalfTreeCreator.cs @ 17180

Last change on this file since 17180 was 17180, checked in by swagner, 2 years ago

#2875: Removed years in copyrights

File size: 3.8 KB
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1#region License Information
2/* HeuristicLab
3 * Copyright (C) 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 HeuristicLab.Common;
23using HeuristicLab.Core;
24using HEAL.Attic;
25using HeuristicLab.PluginInfrastructure;
26
27namespace HeuristicLab.Encodings.SymbolicExpressionTreeEncoding {
28  [NonDiscoverableType]
29  [StorableType("0E43AC76-6CD1-4371-90A6-05F7C5B05EC8")]
30  [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")]
31  public class RampedHalfAndHalfTreeCreator : SymbolicExpressionTreeCreator {
32    [StorableConstructor]
33    protected RampedHalfAndHalfTreeCreator(StorableConstructorFlag _) : base(_) { }
34    protected RampedHalfAndHalfTreeCreator(RampedHalfAndHalfTreeCreator original, Cloner cloner) : base(original, cloner) { }
35
36    public RampedHalfAndHalfTreeCreator() : base() { }
37
38    public override IDeepCloneable Clone(Cloner cloner) {
39      return new RampedHalfAndHalfTreeCreator(this, cloner);
40    }
41
42    protected override ISymbolicExpressionTree Create(IRandom random) {
43      return Create(random, ClonedSymbolicExpressionTreeGrammarParameter.ActualValue,
44        MaximumSymbolicExpressionTreeLengthParameter.ActualValue.Value, MaximumSymbolicExpressionTreeDepthParameter.ActualValue.Value);
45    }
46
47    public override ISymbolicExpressionTree CreateTree(IRandom random, ISymbolicExpressionGrammar grammar, int maxTreeLength, int maxTreeDepth) {
48      return Create(random, grammar, maxTreeLength, maxTreeDepth);
49    }
50
51    /// <summary>
52    /// Create a symbolic expression tree using 'RampedHalfAndHalf' strategy.
53    /// Half the trees are created with the 'Grow' method, and the other half are created with the 'Full' method.
54    /// </summary>
55    /// <param name="random">Random generator</param>
56    /// <param name="grammar">Available tree grammar</param>
57    /// <param name="maxTreeLength">Maximum tree length (this parameter is ignored)</param>
58    /// <param name="maxTreeDepth">Maximum tree depth</param>
59    /// <returns></returns>
60    public static ISymbolicExpressionTree Create(IRandom random, ISymbolicExpressionGrammar grammar, int maxTreeLength, int maxTreeDepth) {
61      var tree = new SymbolicExpressionTree();
62      var rootNode = (SymbolicExpressionTreeTopLevelNode)grammar.ProgramRootSymbol.CreateTreeNode();
63      if (rootNode.HasLocalParameters) rootNode.ResetLocalParameters(random);
64      rootNode.SetGrammar(grammar.CreateExpressionTreeGrammar());
65
66      var startNode = (SymbolicExpressionTreeTopLevelNode)grammar.StartSymbol.CreateTreeNode();
67      if (startNode.HasLocalParameters) startNode.ResetLocalParameters(random);
68      startNode.SetGrammar(grammar.CreateExpressionTreeGrammar());
69
70      rootNode.AddSubtree(startNode);
71
72      double p = random.NextDouble();
73
74      if (p < 0.5)
75        GrowTreeCreator.Create(random, startNode, maxTreeDepth - 2);
76      else
77        FullTreeCreator.Create(random, startNode, maxTreeDepth - 2);
78
79      tree.Root = rootNode;
80      return tree;
81    }
82  }
83}
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