source: trunk/sources/HeuristicLab.Encodings.PermutationEncoding/3.3/Moves/ThreeOpt/StochasticThreeOptSingleMoveGenerator.cs @ 3221

#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 <http://www.gnu.org/licenses/>.
 */
#endregion

using System;
using HeuristicLab.Core;
using HeuristicLab.Data;
using HeuristicLab.Optimization;
using HeuristicLab.Parameters;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.Encodings.PermutationEncoding {
  [Item("StochasticThreeOptSingleMoveGenerator", "Randomly samples one from all possible 3-opt moves from a given permutation.")]
  [StorableClass]
  public class StochasticThreeOptSingleMoveGenerator : ThreeOptMoveGenerator, IStochasticOperator, ISingleMoveGenerator {
    public ILookupParameter<IRandom> RandomParameter {
      get { return (ILookupParameter<IRandom>)Parameters["Random"]; }
    }

    public StochasticThreeOptSingleMoveGenerator()
      : base() {
      Parameters.Add(new LookupParameter<IRandom>("Random", "The random number generator."));
    }

    public static ThreeOptMove Apply(Permutation permutation, IRandom random) {
      int length = permutation.Length;
      int index1, index2, index3;
      index1 = random.Next(length - 1);
      do {
        index2 = random.Next(index1, length);
      } while (index2 - index1 >= length - 2);
      do {
        index3 = random.Next(length - index2 + index1);
      } while (index3 == index1);
      
      return new ThreeOptMove(index1, index2, index3);
    }

    protected override ThreeOptMove[] GenerateMoves(Permutation permutation) {
      IRandom random = RandomParameter.ActualValue;
      return new ThreeOptMove[] { Apply(permutation, random) };
    }
  }
}