1  #region License Information


2  /* HeuristicLab


3  * Copyright (C) 20022013 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 


22  using System.Collections.Generic;


23  using System.Linq;


24  using HeuristicLab.Common;


25  using HeuristicLab.Encodings.IntegerVectorEncoding;


26  using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;


27  using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;


28  using HeuristicLab.Problems.GrammaticalEvolution.Mappers;


29  using HeuristicLab.Random;


30 


31  namespace HeuristicLab.Problems.GrammaticalEvolution {


32  /// <summary>


33  /// GenotypeToPhenotypeMapper


34  /// </summary>


35  public abstract class GenotypeToPhenotypeMapper : IntegerVectorOperator, IGenotypeToPhenotypeMapper {


36 


37  [StorableConstructor]


38  protected GenotypeToPhenotypeMapper(bool deserializing) : base(deserializing) { }


39  protected GenotypeToPhenotypeMapper(GenotypeToPhenotypeMapper original, Cloner cloner) : base(original, cloner) { }


40  protected GenotypeToPhenotypeMapper() : base() { }


41 


42  public abstract SymbolicExpressionTree Map(ISymbolicExpressionGrammar grammar,


43  IntegerVector genotype);


44 


45  /// <summary>


46  /// Randomly returns a terminal node for the given <paramref name="parentNode"/>.


47  /// (A terminal has got a minimum and maximum arity of 0.)


48  /// </summary>


49  /// <param name="parentNode">parent node for which a child node is returned randomly</param>


50  /// <param name="grammar">grammar definition to determine the allowed child symbols for parentNode</param>


51  /// <returns>randomly chosen terminal node with arity 0</returns>


52  protected ISymbolicExpressionTreeNode GetRandomTerminalNode(ISymbolicExpressionTreeNode parentNode,


53  ISymbolicExpressionGrammar grammar) {


54  // only select specific symbols, which can be interpreted ...


55  var possibleSymbolsList = (from s in grammar.GetAllowedChildSymbols(parentNode.Symbol)


56  where s.InitialFrequency > 0.0


57  where s.MaximumArity == 0


58  where s.MinimumArity == 0


59  select s).ToList();


60  // TODO: Check, if symbol list is empty (no terminal nodes found)  what should happen?


61  var newNode = possibleSymbolsList.SelectRandom(new MersenneTwister()).CreateTreeNode();


62  if (newNode.HasLocalParameters) newNode.ResetLocalParameters(new MersenneTwister());


63  return newNode;


64  }


65 


66 


67  /// <summary>


68  /// Returns a randomly chosen child node for the given <paramref name="parentNode"/>.


69  /// </summary>


70  /// <param name="parentNode">parent node to find a child node randomly for</param>


71  /// <param name="genotype">integer vector, which should be mapped to a tree</param>


72  /// <param name="grammar">grammar definition used to define the allowed child symbols</param>


73  /// <param name="genotypeIndex">index in the integer vector; can be greater than vector length</param>


74  /// <returns>randomly chosen child node for parentNode</returns>


75  protected ISymbolicExpressionTreeNode GetNewChildNode(ISymbolicExpressionTreeNode parentNode,


76  IntegerVector genotype,


77  ISymbolicExpressionGrammar grammar,


78  int genotypeIndex) {


79 


80  // only select specific symbols, which can be interpreted ...


81  IEnumerable<ISymbol> symbolList = (from s in grammar.GetAllowedChildSymbols(parentNode.Symbol)


82  where s.InitialFrequency > 0.0


83  select s).ToList();


84  int prodRuleCount = symbolList.Count();


85  int prodRuleIndex = genotype[genotypeIndex % genotype.Length] % prodRuleCount;


86 


87  var newNode = symbolList.ElementAt(prodRuleIndex).CreateTreeNode();


88  if (newNode.HasLocalParameters) newNode.ResetLocalParameters(new MersenneTwister());


89  return newNode;


90  }


91  }


92  }

