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source: branches/Persistence Test/HeuristicLab.GP/3.4/Recombination/SizeConstrictedGPCrossoverBase.cs @ 3703

Last change on this file since 3703 was 1286, checked in by gkronber, 16 years ago

Adapted GP crossover operators to match the new design for crossover operators. #512 (GP crossover operators should be changed to match the new design of crossover operators (see #475)).

File size: 3.2 KB
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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 System;
23using System.Collections.Generic;
24using System.Linq;
25using System.Text;
26using HeuristicLab.Core;
27using HeuristicLab.Operators;
28using HeuristicLab.Random;
29using HeuristicLab.Data;
30using HeuristicLab.Constraints;
31using System.Diagnostics;
32
33namespace HeuristicLab.GP {
34  public abstract class SizeConstrictedGPCrossoverBase : GPCrossoverBase {
35
36    private int MaxRecombinationTries { get { return 20; } }
37
38    public SizeConstrictedGPCrossoverBase()
39      : base() {
40      AddVariableInfo(new VariableInfo("MaxTreeHeight", "The maximal allowed height of the tree", typeof(IntData), VariableKind.In));
41      AddVariableInfo(new VariableInfo("MaxTreeSize", "The maximal allowed size (number of nodes) of the tree", typeof(IntData), VariableKind.In));
42    }
43
44    internal override IFunctionTree Cross(IScope scope, TreeGardener gardener, IRandom random, IFunctionTree tree0, IFunctionTree tree1) {
45      int maxTreeHeight = GetVariableValue<IntData>("MaxTreeHeight", scope, true).Data;
46      int maxTreeSize = GetVariableValue<IntData>("MaxTreeSize", scope, true).Data;
47
48      // when tree0 is terminal then try to cross into tree1, when tree1 is also terminal just return tree0 unchanged.
49      IFunctionTree newTree;
50      int tries = 0;
51      do {
52        if (tries++ > MaxRecombinationTries)
53          // if after so many tries it was not possible to create a solution within the given size constraints just return the tree without changes.
54          return tree0;
55        if (tree0.SubTrees.Count > 0) {
56          newTree = Cross(gardener, random, (IFunctionTree)tree0.Clone(), (IFunctionTree)tree1.Clone(), maxTreeSize, maxTreeHeight);
57        } else if (tree1.SubTrees.Count > 0) {
58          newTree = Cross(gardener, random, (IFunctionTree)tree1.Clone(), (IFunctionTree)tree0.Clone(), maxTreeSize, maxTreeHeight);
59        } else newTree = tree0;
60      } while (newTree.Size > maxTreeSize || newTree.Height > maxTreeHeight);
61      return newTree;
62    }
63
64    internal abstract IFunctionTree Cross(TreeGardener gardener, IRandom random, IFunctionTree tree0, IFunctionTree tree1, int maxTreeSize, int maxTreeHeight);
65
66    //private IFunctionTree TakeNextParent(IScope scope) {
67    //  IFunctionTree parent = GetVariableValue<IFunctionTree>("FunctionTree", scope.SubScopes[0], false);
68    //  scope.RemoveSubScope(scope.SubScopes[0]);
69    //  return parent;
70    //}
71  }
72}
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