#region License Information
/* HeuristicLab
* Copyright (C) 2002-2018 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
*
* This file is part of HeuristicLab.
*
* HeuristicLab is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* HeuristicLab is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with HeuristicLab. If not, see .
*/
#endregion
using System;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
namespace HeuristicLab.Encodings.RealVectorEncoding {
///
/// Discrete crossover for real vectors: For each position in the new vector an allele
/// of one of the parents is randomly selected.
///
///
/// This operator is also called dominant recombination and unlike other crossovers works on more than two parents also.
/// It is implemented as described in Beyer, H.-G. and Schwefel, H.-P. 2002. Evolution Strategies - A Comprehensive Introduction Natural Computing, 1, pp. 3-52.
///
[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. 3-52.")]
[StorableClass]
public class DiscreteCrossover : RealVectorCrossover {
[StorableConstructor]
protected DiscreteCrossover(bool deserializing) : base(deserializing) { }
protected DiscreteCrossover(DiscreteCrossover original, Cloner cloner) : base(original, cloner) { }
public DiscreteCrossover() : base() { }
public override IDeepCloneable Clone(Cloner cloner) {
return new DiscreteCrossover(this, cloner);
}
///
/// Performs a discrete crossover operation on multiple parents.
///
/// Thrown when the vectors of the parents are of different length.
/// A random number generator.
/// An array containing the parents that should be crossed.
/// The newly created real vector, resulting from the crossover operation.
public static RealVector Apply(IRandom random, ItemArray parents) {
int length = parents[0].Length;
for (int i = 0; i < parents.Length; i++) {
if (parents[i].Length != length)
throw new ArgumentException("DiscreteCrossover: The parents' vectors are of different length.", "parents");
}
RealVector result = new RealVector(length);
for (int i = 0; i < length; i++) {
result[i] = parents[random.Next(parents.Length)][i];
}
return result;
}
///
/// Checks number of parents and forwards the call to .
///
/// Thrown when contains less than 2 elements.
/// The random number generator.
/// The collection of parents (must be of size 2 or greater).
/// The real vector resulting from the crossover.
protected override RealVector Cross(IRandom random, ItemArray parents) {
if (parents.Length < 2) throw new ArgumentException("DiscreteCrossover: The number of parents is less than 2.", "parents");
return Apply(random, parents);
}
}
}