source: branches/VRP/HeuristicLab.Problems.VehicleRouting/3.4/Encodings/Prins/PrinsEncoding.cs @ 6838

Last change on this file since 6838 was 6838, checked in by svonolfe, 8 years ago

Updated interface of evaluator - added individual (#1177)

File size: 5.6 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2010 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 HeuristicLab.Common;
23using HeuristicLab.Core;
24using HeuristicLab.Data;
25using HeuristicLab.Encodings.PermutationEncoding;
26using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
27using System.Collections.Generic;
28using HeuristicLab.Problems.VehicleRouting.Encodings.General;
29using System;
30using HeuristicLab.Problems.VehicleRouting.Interfaces;
31using HeuristicLab.Problems.VehicleRouting.ProblemInstances;
32
33namespace HeuristicLab.Problems.VehicleRouting.Encodings.Prins {
34  [Item("PrinsEncoding", "Represents an Prins encoding of VRP solutions. It is implemented as described in Prins, C. (2004). A simple and effective evolutionary algorithm for the vehicle routing problem. Computers & Operations Research, 12:1985-2002.")]
35  [StorableClass]
36  public class PrinsEncoding : PermutationEncoding {
37    #region IVRPEncoding Members
38    public override List<Tour> GetTours() {
39      List<Tour> result = new List<Tour>();
40
41      int cities = ProblemInstance.Cities.Value;
42
43      //Split permutation into vector P
44      int[] P = new int[cities + 1];
45      for (int i = 0; i <= cities; i++)
46        P[i] = -1;
47
48      double[] V = new double[cities + 1];
49      V[0] = 0;
50      for (int i = 1; i <= cities; i++) {
51        V[i] = double.MaxValue;
52      }
53
54      for (int i = 1; i <= cities; i++) {
55        int j = i;
56        Tour tour = new Tour();
57        bool feasible = true;
58
59        do {
60          tour.Stops.Add(this[j-1] + 1);
61
62          VRPEvaluation eval =
63            ProblemInstance.EvaluateTour(tour, this);
64
65          double cost = eval.Quality;
66          feasible = ProblemInstance.Feasible(eval);
67
68          if (feasible || j == i) {
69            if (V[i - 1] + cost < V[j]) {
70              V[j] = V[i - 1] + cost;
71              P[j] = i - 1;
72            }
73            j++;
74          }
75
76        } while (j <= cities && feasible);
77      }
78
79      //extract VRP solution from vector P
80      int index = 0;
81      int index2 = cities;
82      Tour trip = null;
83      do {
84        index = P[index2];
85        trip = new Tour();
86
87        for (int k = index + 1; k <= index2; k++) {
88          trip.Stops.Add(this[k - 1] + 1);
89        }
90
91        if (trip.Stops.Count > 0)
92          result.Add(trip);
93
94        index2 = index;
95      } while (index != 0);
96
97      //if there are too many vehicles - repair
98      while (result.Count > ProblemInstance.Vehicles.Value) {
99        Tour tour = result[result.Count - 1];
100
101        //find predecessor / successor in permutation
102        int predecessorIndex = Array.IndexOf(this.array, tour.Stops[0] - 1) - 1;
103        if (predecessorIndex >= 0) {
104          int predecessor = this[predecessorIndex] + 1;
105
106          foreach (Tour t in result) {
107            int insertPosition = t.Stops.IndexOf(predecessor) + 1;
108            if (insertPosition != -1) {
109              t.Stops.InsertRange(insertPosition, tour.Stops);
110              break;
111            }
112          }
113        } else {
114          int successorIndex = Array.IndexOf(this.array,
115            tour.Stops[tour.Stops.Count - 1] - 1) + 1;
116          int successor = this[successorIndex] + 1;
117
118          foreach (Tour t in result) {
119            int insertPosition = t.Stops.IndexOf(successor);
120            if (insertPosition != -1) {
121              t.Stops.InsertRange(insertPosition, tour.Stops);
122              break;
123            }
124          }
125        }
126
127        result.Remove(tour);
128      }
129
130      return result;
131    }
132    #endregion
133    public PrinsEncoding(Permutation permutation, IVRPProblemInstance problemInstance)
134      : base(permutation, problemInstance) {
135    }
136
137    [StorableConstructor]
138    private PrinsEncoding(bool serializing)
139      : base(serializing) {
140    }
141
142    public override IDeepCloneable Clone(Cloner cloner) {
143      return new PrinsEncoding(this, cloner);
144    }
145
146    protected PrinsEncoding(PrinsEncoding original, Cloner cloner)
147      : base(original, cloner) {
148    }
149
150    public static PrinsEncoding ConvertFrom(IVRPEncoding encoding, IVRPProblemInstance problemInstance) {
151      List<Tour> tours = encoding.GetTours();
152      List<int> route = new List<int>();
153
154      foreach (Tour tour in tours) {
155        foreach (int city in tour.Stops)
156          route.Add(city - 1);
157      }
158
159      return new PrinsEncoding(
160        new Permutation(PermutationTypes.RelativeUndirected, route.ToArray()), problemInstance);
161    }
162
163    public static PrinsEncoding ConvertFrom(List<int> routeParam, IVRPProblemInstance problemInstance) {
164      List<int> route = new List<int>(routeParam);
165
166      while (route.Remove(0)) { //remove all delimiters (0)
167      }
168
169      for (int i = 0; i < route.Count; i++)
170        route[i]--;
171
172      return new PrinsEncoding(
173        new Permutation(PermutationTypes.RelativeUndirected, route.ToArray()), problemInstance);
174    }
175  }
176}
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