1  #region License Information


2  /* HeuristicLab


3  * Copyright (C) 20022019 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;


23  using HeuristicLab.Common;


24  using HeuristicLab.Core;


25  using HEAL.Attic;


26 


27  namespace HeuristicLab.Encodings.RealVectorEncoding {


28  /// <summary>


29  /// Discrete crossover for real vectors: For each position in the new vector an allele


30  /// of one of the parents is randomly selected.


31  /// </summary>


32  /// <remarks>


33  /// This operator is also called dominant recombination and unlike other crossovers works on more than two parents also.<br />


34  /// It is implemented as described in Beyer, H.G. and Schwefel, H.P. 2002. Evolution Strategies  A Comprehensive Introduction Natural Computing, 1, pp. 352.


35  /// </remarks>


36  [Item("DiscreteCrossover", "Discrete crossover for real vectors: Creates a new offspring by combining the alleles in the parents such that each allele is randomly selected from one parent. It is implemented as described in Beyer, H.G. and Schwefel, H.P. 2002. Evolution Strategies  A Comprehensive Introduction Natural Computing, 1, pp. 352.")]


37  [StorableType("F88C9256B1C943B4B8EBFAF2357A0310")]


38  public class DiscreteCrossover : RealVectorCrossover {


39  [StorableConstructor]


40  protected DiscreteCrossover(StorableConstructorFlag _) : base(_) { }


41  protected DiscreteCrossover(DiscreteCrossover original, Cloner cloner) : base(original, cloner) { }


42  public DiscreteCrossover() : base() { }


43 


44  public override IDeepCloneable Clone(Cloner cloner) {


45  return new DiscreteCrossover(this, cloner);


46  }


47 


48  /// <summary>


49  /// Performs a discrete crossover operation on multiple parents.


50  /// </summary>


51  /// <exception cref="ArgumentException">Thrown when the vectors of the parents are of different length.</exception>


52  /// <param name="random">A random number generator.</param>


53  /// <param name="parents">An array containing the parents that should be crossed.</param>


54  /// <returns>The newly created real vector, resulting from the crossover operation.</returns>


55  public static RealVector Apply(IRandom random, ItemArray<RealVector> parents) {


56  int length = parents[0].Length;


57 


58  for (int i = 0; i < parents.Length; i++) {


59  if (parents[i].Length != length)


60  throw new ArgumentException("DiscreteCrossover: The parents' vectors are of different length.", "parents");


61  }


62 


63  RealVector result = new RealVector(length);


64  for (int i = 0; i < length; i++) {


65  result[i] = parents[random.Next(parents.Length)][i];


66  }


67 


68  return result;


69  }


70 


71  /// <summary>


72  /// Checks number of parents and forwards the call to <see cref="Apply(IRandom, ItemArray<RealVector>)"/>.


73  /// </summary>


74  /// <exception cref="ArgumentException">Thrown when <paramref name="parents"/> contains less than 2 elements.</exception>


75  /// <param name="random">The random number generator.</param>


76  /// <param name="parents">The collection of parents (must be of size 2 or greater).</param>


77  /// <returns>The real vector resulting from the crossover.</returns>


78  protected override RealVector Cross(IRandom random, ItemArray<RealVector> parents) {


79  if (parents.Length < 2) throw new ArgumentException("DiscreteCrossover: The number of parents is less than 2.", "parents");


80  return Apply(random, parents);


81  }


82  }


83  }

