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source: trunk/sources/HeuristicLab.GP/Manipulation/OnePointShaker.cs @ 1500

Last change on this file since 1500 was 1039, checked in by gkronber, 16 years ago

fixed #439 (One-Point Shaker does not work for terminals without parameters)

File size: 3.8 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 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.Selection;
31
32namespace HeuristicLab.GP {
33  public class OnePointShaker : DelegatingOperator {
34    public override string Description {
35      get { return "Selects a random node of all tree-nodes that have a '"+FunctionBase.MANIPULATION+"' variable defined and manipulates the selected node."; }
36    }
37
38    public OnePointShaker()
39      : base() {
40      AddVariableInfo(new VariableInfo("OperatorLibrary", "Operator library that defines mutation operations for operators", typeof(GPOperatorLibrary), VariableKind.In));
41      AddVariableInfo(new VariableInfo("Random", "A random generator (uniform)", typeof(MersenneTwister), VariableKind.In));
42      AddVariableInfo(new VariableInfo("ShakingFactor", "Factor that determines the force of the shaking operation", typeof(DoubleData), VariableKind.In));
43      AddVariableInfo(new VariableInfo("FunctionTree", "The function tree that should be mutated", typeof(IFunctionTree), VariableKind.In | VariableKind.Out));
44    }
45
46    public override IOperation Apply(IScope scope) {
47      GPOperatorLibrary library = GetVariableValue<GPOperatorLibrary>("OperatorLibrary", scope, true);
48      IFunctionTree tree = GetVariableValue<IFunctionTree>("FunctionTree", scope, false);
49      MersenneTwister mt = GetVariableValue<MersenneTwister>("Random", scope, true);
50      TreeGardener gardener = new TreeGardener(mt, library);
51
52      // get all nodes for which a manipulation is defined
53      var parametricBranches = gardener.GetAllSubTrees(tree).Where(branch => branch.Function.GetVariable(FunctionBase.MANIPULATION) != null);
54
55      if(parametricBranches.Count() == 0) return null; // don't manipulate anything if there are no nodes with a manipulation operator
56
57      IFunctionTree selectedBranch = parametricBranches.ElementAt(mt.Next(parametricBranches.Count()));
58      IOperator mutation = (IOperator)selectedBranch.Function.GetVariable(FunctionBase.MANIPULATION).Value;
59      CompositeOperation next = new CompositeOperation();
60
61      // store all local variables into a temporary scope
62      Scope tempScope = new Scope("Temp. manipulation scope");
63      foreach(IVariable variable in selectedBranch.LocalVariables) {
64        tempScope.AddVariable(variable);
65      }
66
67      // save the exising sub-scops in a backup scope
68      Scope backupScope = new Scope("backup");
69      foreach (Scope subScope in scope.SubScopes) {
70        backupScope.AddSubScope(subScope);
71      }
72
73      // add the new sub-scopes
74      scope.AddSubScope(tempScope);
75      scope.AddSubScope(backupScope);
76
77      // the next operation should first manipulate and then restore the sub-scopes from the backup scope
78      next.AddOperation(new AtomicOperation(mutation, tempScope));
79      next.AddOperation(new AtomicOperation(new RightReducer(), scope));
80
81      return next;
82    }
83  }
84}
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