source: branches/HeuristicLab.BinPacking/HeuristicLab.Problems.BinPacking.2D/3.3/Evaluators/PackingRatioEvaluator.cs @ 14151

Last change on this file since 14151 was 14151, checked in by gkronber, 5 years ago

#1966: added abstract problem and move evaluator classes and implemented 2d bin packing problem based on integer vector encoding

File size: 2.6 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2015 Joseph Helm and 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
22using System;
23using System.Linq;
24using HeuristicLab.Core;
25using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
26using HeuristicLab.Common;
27
28namespace HeuristicLab.Problems.BinPacking2D {
29  [Item("Packing-Ratio Evaluator (2d)", "Calculates the ratio between packed and unpacked space.")]
30  [StorableClass]
31  public class PackingRatioEvaluator : Item, IEvaluator {
32
33    [StorableConstructor]
34    protected PackingRatioEvaluator(bool deserializing) : base(deserializing) { }
35    protected PackingRatioEvaluator(PackingRatioEvaluator original, Cloner cloner)
36      : base(original, cloner) {
37    }
38    public PackingRatioEvaluator() : base() { }
39    public override IDeepCloneable Clone(Cloner cloner) {
40      return new PackingRatioEvaluator(this, cloner);
41    }
42
43    #region IEvaluator Members
44    public double Evaluate(Solution solution) {
45      return CalculatePackingRatio(solution);
46    }
47
48    /*
49        Falkenauer:1996 - A Hybrid Grouping Genetic Algorithm for Bin Packing
50       
51        fBPP = (SUM[i=1..N](Fi / C)^k)/N
52        N.......the number of bins used in the solution,
53        Fi......the sum of sizes of the items in the bin i (the fill of the bin),
54        C.......the bin capacity and
55        k.......a constant, k>1.
56     */
57    public static double CalculatePackingRatio(Solution solution) {
58      int nrOfBins = solution.NrOfBins;
59      double result = 0;
60      const double k = 2;
61      for (int i = 0; i < nrOfBins; i++) {
62        double f = solution.BinPackings[i].ItemMeasures.Sum(kvp => kvp.Value.Volume);
63        double c = solution.BinPackings[i].BinMeasures.Volume;
64        result += Math.Pow(f / c, k);
65      }
66
67      result = result / nrOfBins;
68      return result;
69    }
70
71    #endregion
72  }
73}
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