1  #region License Information


2  /* HeuristicLab


3  * Copyright (C) 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 HeuristicLab.Data;


26  using HeuristicLab.Parameters;


27  using HEAL.Attic;


28 


29  namespace HeuristicLab.Encodings.IntegerVectorEncoding {


30  /// <summary>


31  /// The rounded uniform arithmetic crossover (continuous recombination) constructs an offspring by calculating x = alpha * p1 + (1alpha) * p2 for a position x in the vector with a given probability (otherwise p1 is taken at this position).


32  /// </summary>


33  [Item("RoundedUniformSomePositionsArithmeticCrossover", "The uniform some positions arithmetic crossover (continuous recombination) constructs an offspring by calculating x = alpha * p1 + (1alpha) * p2 for a position x in the vector with a given probability (otherwise p1 is taken at this position).")]


34  [StorableType("8393AFC2FAA547A8A1E3E6DEABE71B2F")]


35  public class RoundedUniformArithmeticCrossover : BoundedIntegerVectorCrossover, IBoundedIntegerVectorOperator {


36 


37  /// <summary>


38  /// The alpha parameter needs to be in the interval (0;1) and specifies how close the resulting offspring should be either to parent1 (alpha > 0) or parent2 (alpha > 1).


39  /// </summary>


40  public ValueLookupParameter<DoubleValue> AlphaParameter {


41  get { return (ValueLookupParameter<DoubleValue>)Parameters["Alpha"]; }


42  }


43  /// <summary>


44  /// The probability in the range (0;1] for each position in the vector to be crossed.


45  /// </summary>


46  public ValueLookupParameter<DoubleValue> ProbabilityParameter {


47  get { return (ValueLookupParameter<DoubleValue>)Parameters["Probability"]; }


48  }


49 


50  [StorableConstructor]


51  protected RoundedUniformArithmeticCrossover(StorableConstructorFlag _) : base(_) { }


52  protected RoundedUniformArithmeticCrossover(RoundedUniformArithmeticCrossover original, Cloner cloner) : base(original, cloner) { }


53  /// <summary>


54  /// Initializes a new instance with two parameters (<c>Alpha</c> and <c>Probability</c>).


55  /// </summary>


56  public RoundedUniformArithmeticCrossover()


57  : base() {


58  Parameters.Add(new ValueLookupParameter<DoubleValue>("Alpha", "The alpha value in the range (0;1) that defines whether the point should be close to parent1 (>1) or parent2 (>0)", new DoubleValue(0.5)));


59  Parameters.Add(new ValueLookupParameter<DoubleValue>("Probability", "The probability for crossing a position in the range (0;1]", new DoubleValue(1)));


60  }


61 


62  public override IDeepCloneable Clone(Cloner cloner) {


63  return new RoundedUniformArithmeticCrossover(this, cloner);


64  }


65 


66  /// <summary>


67  /// Performs the arithmetic crossover on some positions by taking either x = alpha * p1 + (1  alpha) * p2 or x = p1 depending on the probability for a gene to be crossed.


68  /// </summary>


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


70  /// <param name="parent1">The first parent vector.</param>


71  /// <param name="parent2">The second parent vector.</param>


72  /// <param name="bounds">The bounds and step size for each dimension (will be cycled in case there are less rows than elements in the parent vectors).</param>


73  /// <param name="alpha">The alpha parameter (<see cref="AlphaParameter"/>).</param>


74  /// <param name="probability">The probability parameter (<see cref="ProbabilityParameter"/>).</param>


75  /// <returns>The vector resulting from the crossover.</returns>


76  public static IntegerVector Apply(IRandom random, IntegerVector parent1, IntegerVector parent2, IntMatrix bounds, DoubleValue alpha, DoubleValue probability) {


77  int length = parent1.Length;


78  if (length != parent2.Length) throw new ArgumentException("RoundedUniformArithmeticCrossover: The parent vectors are of different length.", "parent1");


79  if (alpha.Value < 0  alpha.Value > 1) throw new ArgumentException("RoundedUniformArithmeticCrossover: Parameter alpha must be in the range [0;1]", "alpha");


80  if (probability.Value < 0  probability.Value > 1) throw new ArgumentException("RoundedUniformArithmeticCrossover: Parameter probability must be in the range [0;1]", "probability");


81 


82  var result = new IntegerVector(length);


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


84  if (random.NextDouble() < probability.Value) {


85  int min = bounds[i % bounds.Rows, 0], max = bounds[i % bounds.Rows, 1], step = 1;


86  if (bounds.Columns > 2) step = bounds[i % bounds.Rows, 2];


87  max = FloorFeasible(min, max, step, max  1);


88  double value = alpha.Value * parent1[i] + (1  alpha.Value) * parent2[i];


89  result[i] = RoundFeasible(min, max, step, value);


90  } else result[i] = parent1[i];


91  }


92  return result;


93  }


94 


95  /// <summary>


96  /// Checks that there are exactly 2 parents, that the alpha and the probability parameter are not null and fowards the call to the static Apply method.


97  /// </summary>


98  /// <exception cref="ArgumentException">Thrown when there are not exactly two parents.</exception>


99  /// <exception cref="InvalidOperationException">Thrown when either the alpha parmeter or the probability parameter could not be found.</exception>


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


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


102  /// /// <param name="bounds">The bounds and step size for each dimension (will be cycled in case there are less rows than elements in the parent vectors).</param>


103  /// <returns>The vector resulting from the crossover.</returns>


104  protected override IntegerVector CrossBounded(IRandom random, ItemArray<IntegerVector> parents, IntMatrix bounds) {


105  if (parents.Length != 2) throw new ArgumentException("RoundedUniformArithmeticCrossover: There must be exactly two parents.", "parents");


106  if (AlphaParameter.ActualValue == null) throw new InvalidOperationException("RoundedUniformArithmeticCrossover: Parameter " + AlphaParameter.ActualName + " could not be found.");


107  if (ProbabilityParameter.ActualValue == null) throw new InvalidOperationException("RoundedUniformArithmeticCrossover: Parameter " + ProbabilityParameter.ActualName + " could not be found.");


108  return Apply(random, parents[0], parents[1], bounds, AlphaParameter.ActualValue, ProbabilityParameter.ActualValue);


109  }


110  }


111  }

