1 | #region License Information
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2 | /* HeuristicLab
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3 | * Copyright (C) 2002-2008 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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4 | *
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5 | * This file is part of HeuristicLab.
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6 | *
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7 | * HeuristicLab is free software: you can redistribute it and/or modify
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8 | * it under the terms of the GNU General Public License as published by
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9 | * the Free Software Foundation, either version 3 of the License, or
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10 | * (at your option) any later version.
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11 | *
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12 | * HeuristicLab is distributed in the hope that it will be useful,
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13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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15 | * GNU General Public License for more details.
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16 | *
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17 | * You should have received a copy of the GNU General Public License
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18 | * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
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19 | */
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20 | #endregion
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21 |
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22 | using System;
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23 | using System.Collections.Generic;
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24 | using System.Linq;
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25 | using System.Text;
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26 | using HeuristicLab.Core;
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27 | using HeuristicLab.Operators;
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28 | using HeuristicLab.Random;
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29 | using HeuristicLab.Data;
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30 | using HeuristicLab.Constraints;
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31 | using System.Diagnostics;
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32 |
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33 | namespace HeuristicLab.GP {
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34 | public abstract class GPCrossoverBase : OperatorBase {
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35 | private const int MAX_RECOMBINATION_TRIES = 100;
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36 |
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37 | public GPCrossoverBase()
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38 | : base() {
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39 | AddVariableInfo(new VariableInfo("Random", "Pseudo random number generator", typeof(MersenneTwister), VariableKind.In));
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40 | AddVariableInfo(new VariableInfo("OperatorLibrary", "The operator library containing all available operators", typeof(GPOperatorLibrary), VariableKind.In));
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41 | AddVariableInfo(new VariableInfo("FunctionTree", "The tree to mutate", typeof(IFunctionTree), VariableKind.In | VariableKind.New));
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42 | AddVariableInfo(new VariableInfo("TreeSize", "The size (number of nodes) of the tree", typeof(IntData), VariableKind.New));
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43 | AddVariableInfo(new VariableInfo("TreeHeight", "The height of the tree", typeof(IntData), VariableKind.New));
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44 | }
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45 |
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46 | public override IOperation Apply(IScope scope) {
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47 | MersenneTwister random = GetVariableValue<MersenneTwister>("Random", scope, true);
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48 | GPOperatorLibrary opLibrary = GetVariableValue<GPOperatorLibrary>("OperatorLibrary", scope, true);
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49 | TreeGardener gardener = new TreeGardener(random, opLibrary);
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50 |
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51 | if ((scope.SubScopes.Count % 2) != 0)
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52 | throw new InvalidOperationException("Number of parents is not even");
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53 |
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54 | int children = scope.SubScopes.Count / 2;
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55 | for (int i = 0; i < children; i++) {
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56 | IFunctionTree parent0 = TakeNextParent(scope);
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57 | IFunctionTree parent1 = TakeNextParent(scope);
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58 |
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59 | // randomly swap parents to remove a possible bias from selection (e.g. when using gender-specific selection)
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60 | if (random.NextDouble() < 0.5) {
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61 | IFunctionTree tmp = parent0;
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62 | parent0 = parent1;
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63 | parent1 = tmp;
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64 | }
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65 |
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66 | IFunctionTree child = Cross(scope, gardener, random, parent0, parent1);
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67 | Debug.Assert(gardener.IsValidTree(child));
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68 | IScope childScope = new Scope(i.ToString());
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69 | childScope.AddVariable(new HeuristicLab.Core.Variable(scope.TranslateName("FunctionTree"), child));
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70 | childScope.AddVariable(new HeuristicLab.Core.Variable(scope.TranslateName("TreeSize"), new IntData(child.Size)));
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71 | childScope.AddVariable(new HeuristicLab.Core.Variable(scope.TranslateName("TreeHeight"), new IntData(child.Height)));
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72 | scope.AddSubScope(childScope);
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73 | }
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74 |
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75 | return null;
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76 | }
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77 |
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78 | internal abstract IFunctionTree Cross(IScope scope, TreeGardener gardener, MersenneTwister random, IFunctionTree tree0, IFunctionTree tree1);
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79 |
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80 | private IFunctionTree TakeNextParent(IScope scope) {
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81 | IFunctionTree parent = GetVariableValue<IFunctionTree>("FunctionTree", scope.SubScopes[0], false);
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82 | scope.RemoveSubScope(scope.SubScopes[0]);
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83 | return parent;
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84 | }
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85 | }
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86 | }
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