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 System.Collections.Generic;


24  using System.Linq;


25  using HeuristicLab.Common;


26  using HeuristicLab.Core;


27  using HeuristicLab.Encodings.RealVectorEncoding;


28  using HeuristicLab.Optimization;


29  using HEAL.Attic;


30  using HeuristicLab.Problems.TestFunctions.MultiObjective;


31  namespace HeuristicLab.Algorithms.MOCMAEvolutionStrategy {


32  [Item("HypervolumeIndicator", "Selection of Offspring based on contributing Hypervolume")]


33  [StorableType("ADF439D664E44C92A4D3E8C05B050406")]


34  internal class HypervolumeIndicator : Item, IIndicator {


35  #region Constructors and Cloning


36  [StorableConstructor]


37  protected HypervolumeIndicator(StorableConstructorFlag _) : base(_) { }


38  protected HypervolumeIndicator(HypervolumeIndicator original, Cloner cloner) : base(original, cloner) { }


39  public override IDeepCloneable Clone(Cloner cloner) { return new HypervolumeIndicator(this, cloner); }


40  public HypervolumeIndicator() { }


41  #endregion


42 


43  public int LeastContributer(IReadOnlyList<Individual> front, MultiObjectiveBasicProblem<RealVectorEncoding> problem) {


44  var frontCopy = front.Select(x => x.PenalizedFitness).ToList();


45  if (frontCopy.Count <= 1) return 0;


46  var p = problem as MultiObjectiveTestFunctionProblem;


47  var refPoint = BuildReferencePoint(p != null ? frontCopy.Concat(new[] { p.ReferencePoint.CloneAsArray() }) : frontCopy, problem.Maximization);


48  var contributions = Enumerable.Range(0, frontCopy.Count).Select(i => Contribution(frontCopy, i, problem.Maximization, refPoint));


49  return contributions.Select((value, index) => new { value, index }).OrderBy(x => x.value).First().index;


50  }


51 


52  #region Helpers


53  private static double Contribution(IList<double[]> front, int idx, bool[] maximization, double[] refPoint) {


54  var point = front[idx];


55  front.RemoveAt(idx);


56  var contribution = Hypervolume.Calculate(front.ToArray(), refPoint, maximization);


57  front.Insert(idx, point);


58  return contribution;


59  }


60  private static double[] BuildReferencePoint(IEnumerable<double[]> front, IReadOnlyList<bool> maximization) {


61  var refPoint = new double[maximization.Count];


62  foreach (var point in front)


63  for (var i = 0; i < maximization.Count; i++)


64  refPoint[i] = maximization[i] ? Math.Min(refPoint[i], point[i]) : Math.Max(refPoint[i], point[i]);


65  return refPoint;


66  }


67  #endregion


68  }


69  }

