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source: branches/Persistence Test/HeuristicLab.GP.Operators/3.3/Recombination/SizeConstrictedGPCrossoverBase.cs @ 2491

Last change on this file since 2491 was 2222, checked in by gkronber, 15 years ago

Merged changes from GP-refactoring branch back into the trunk #713.

File size: 2.8 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2008 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.Core;
23using HeuristicLab.Data;
24using HeuristicLab.GP.Interfaces;
25
26namespace HeuristicLab.GP.Operators {
27  public abstract class SizeConstrictedGPCrossoverBase : GPCrossoverBase {
28
29    private int MaxRecombinationTries { get { return 20; } }
30
31    public SizeConstrictedGPCrossoverBase()
32      : base() {
33      AddVariableInfo(new VariableInfo("MaxTreeHeight", "The maximal allowed height of the tree", typeof(IntData), VariableKind.In));
34      AddVariableInfo(new VariableInfo("MaxTreeSize", "The maximal allowed size (number of nodes) of the tree", typeof(IntData), VariableKind.In));
35    }
36
37    internal override IFunctionTree Cross(IScope scope, TreeGardener gardener, IRandom random, IFunctionTree tree0, IFunctionTree tree1) {
38      int maxTreeHeight = GetVariableValue<IntData>("MaxTreeHeight", scope, true).Data;
39      int maxTreeSize = GetVariableValue<IntData>("MaxTreeSize", scope, true).Data;
40
41      // when tree0 is terminal then try to cross into tree1, when tree1 is also terminal just return tree0 unchanged.
42      IFunctionTree newTree;
43      int tries = 0;
44      do {
45        if (tries++ > MaxRecombinationTries)
46          // if after so many tries it was not possible to create a solution within the given size constraints just return the tree without changes.
47          return tree0;
48        if (tree0.SubTrees.Count > 0) {
49          newTree = Cross(gardener, random, (IFunctionTree)tree0.Clone(), (IFunctionTree)tree1.Clone(), maxTreeSize, maxTreeHeight);
50        } else if (tree1.SubTrees.Count > 0) {
51          newTree = Cross(gardener, random, (IFunctionTree)tree1.Clone(), (IFunctionTree)tree0.Clone(), maxTreeSize, maxTreeHeight);
52        } else newTree = tree0;
53      } while (newTree.GetSize() > maxTreeSize || newTree.GetHeight() > maxTreeHeight);
54      return newTree;
55    }
56
57    internal abstract IFunctionTree Cross(TreeGardener gardener, IRandom random, IFunctionTree tree0, IFunctionTree tree1, int maxTreeSize, int maxTreeHeight);
58  }
59}
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