#region License Information
/* HeuristicLab
* Copyright (C) 2002-2010 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.PermutationEncoding {
///
/// An operator which performs a slight variant of the order crossover on two permutations.
///
///
/// It is implemented as described in Affenzeller, M. et al. 2009. Genetic Algorithms and Genetic Programming - Modern Concepts and Practical Applications. CRC Press. p. 135.
/// Crosses two permutations by copying a randomly chosen interval from the first permutation, preserving
/// the positions. But then, instead of starting from the end of the copied interval, the missing values are copied from the start of the permutation in the order they occur.
///
[Item("OrderCrossover2", "An operator which performs an order crossover of two permutations. It is implemented as described in Affenzeller, M. et al. 2009. Genetic Algorithms and Genetic Programming - Modern Concepts and Practical Applications. CRC Press. p. 135.")]
[StorableClass]
public class OrderCrossover2 : PermutationCrossover {
[StorableConstructor]
protected OrderCrossover2(bool deserializing) : base(deserializing) { }
protected OrderCrossover2(OrderCrossover2 original, Cloner cloner) : base(original, cloner) { }
public OrderCrossover2() : base() { }
public override IDeepCloneable Clone(Cloner cloner) {
return new OrderCrossover2(this, cloner);
}
///
/// Performs a slight variation of the order crossover of two permutations.
///
/// Thrown when and are not of equal length.
///
/// Crosses two permutations by copying a randomly chosen interval from the first permutation, preserving
/// the positions. Then, from the beginning of the permutation, copies the missing values from the second permutation
/// in the order they occur.
///
/// A random number generator.
/// The first parent permutation to cross.
/// The second parent permutation to cross.
/// The new permutation resulting from the crossover.
public static Permutation Apply(IRandom random, Permutation parent1, Permutation parent2) {
if (parent1.Length != parent2.Length) throw new ArgumentException("OrderCrossover2: The parent permutations are of unequal length.");
int[] result = new int[parent1.Length];
bool[] copied = new bool[result.Length];
int breakPoint1 = random.Next(result.Length - 1);
int breakPoint2 = random.Next(breakPoint1 + 1, result.Length);
for (int i = breakPoint1; i <= breakPoint2; i++) { // copy part of first permutation
result[i] = parent1[i];
copied[parent1[i]] = true;
}
int index = 0;
for (int i = 0; i < parent2.Length; i++) { // copy remaining part of second permutation
if (index == breakPoint1) { // skip already copied part
index = breakPoint2 + 1;
}
if (!copied[parent2[i]]) {
result[index] = parent2[i];
index++;
}
}
return new Permutation(parent1.PermutationType, result);
}
///
/// Checks number of parents and calls .
///
/// Thrown if there are not exactly two parents.
/// A random number generator.
/// An array containing the two permutations that should be crossed.
/// The new permutation resulting from the crossover.
protected override Permutation Cross(IRandom random, ItemArray parents) {
if (parents.Length != 2) throw new InvalidOperationException("OrderCrossover2: Number of parents is not equal to 2.");
return Apply(random, parents[0], parents[1]);
}
}
}