[7373] | 1 | #region License Information
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| 2 | /* HeuristicLab
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[15504] | 3 | * Copyright (C) 2002-2017 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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[7373] | 4 | *
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| 5 | * This file is part of HeuristicLab.
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| 6 | *
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| 7 | * HeuristicLab is free software: you can redistribute it and/or modify
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| 8 | * it under the terms of the GNU General Public License as published by
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| 9 | * the Free Software Foundation, either version 3 of the License, or
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| 10 | * (at your option) any later version.
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| 11 | *
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| 12 | * HeuristicLab is distributed in the hope that it will be useful,
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| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 15 | * GNU General Public License for more details.
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| 16 | *
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| 17 | * You should have received a copy of the GNU General Public License
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| 18 | * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
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| 19 | */
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| 20 | #endregion
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| 21 |
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[7407] | 22 | using System;
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[7373] | 23 | using System.Collections.Generic;
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| 24 | using System.Linq;
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[7593] | 25 | using System.Threading;
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[7373] | 26 | using HeuristicLab.Common;
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| 27 | using HeuristicLab.Core;
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| 28 | using HeuristicLab.Data;
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| 29 | using HeuristicLab.Encodings.IntegerVectorEncoding;
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| 30 | using HeuristicLab.Parameters;
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| 31 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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[7813] | 32 | using HeuristicLab.Random;
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[7373] | 33 |
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[7407] | 34 | namespace HeuristicLab.Problems.GeneralizedQuadraticAssignment {
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[15555] | 35 | /// <summary>
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| 36 | /// This is an implementation of the algorithm described in Mateus, G.R., Resende, M.G.C. & Silva, R.M.A. J Heuristics (2011) 17: 527. https://doi.org/10.1007/s10732-010-9144-0
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| 37 | /// </summary>
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[7373] | 38 | [Item("GreedyRandomizedSolutionCreator", "Creates a solution according to the procedure described in Mateus, G., Resende, M., and Silva, R. 2011. GRASP with path-relinking for the generalized quadratic assignment problem. Journal of Heuristics 17, Springer Netherlands, pp. 527-565.")]
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| 39 | [StorableClass]
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[15504] | 40 | public class GreedyRandomizedSolutionCreator : GQAPStochasticSolutionCreator {
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[7373] | 41 |
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| 42 | public IValueLookupParameter<IntValue> MaximumTriesParameter {
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| 43 | get { return (IValueLookupParameter<IntValue>)Parameters["MaximumTries"]; }
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| 44 | }
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[7593] | 45 | public IValueLookupParameter<BoolValue> CreateMostFeasibleSolutionParameter {
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| 46 | get { return (IValueLookupParameter<BoolValue>)Parameters["CreateMostFeasibleSolution"]; }
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| 47 | }
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[7373] | 48 |
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| 49 | [StorableConstructor]
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| 50 | protected GreedyRandomizedSolutionCreator(bool deserializing) : base(deserializing) { }
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| 51 | protected GreedyRandomizedSolutionCreator(GreedyRandomizedSolutionCreator original, Cloner cloner)
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| 52 | : base(original, cloner) { }
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| 53 | public GreedyRandomizedSolutionCreator()
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| 54 | : base() {
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[7593] | 55 | Parameters.Add(new ValueLookupParameter<IntValue>("MaximumTries", "The maximum number of tries to create a feasible solution after which an exception is thrown. If it is set to 0 or a negative value there will be an infinite number of attempts.", new IntValue(100000)));
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| 56 | Parameters.Add(new ValueLookupParameter<BoolValue>("CreateMostFeasibleSolution", "If this is set to true the operator will always succeed, and outputs the solution with the least violation instead of throwing an exception.", new BoolValue(false)));
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[7373] | 57 | }
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| 58 |
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| 59 | public override IDeepCloneable Clone(Cloner cloner) {
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| 60 | return new GreedyRandomizedSolutionCreator(this, cloner);
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| 61 | }
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| 62 |
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[15504] | 63 | public static IntegerVector CreateSolution(IRandom random, GQAPInstance problemInstance,
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[7970] | 64 | int maximumTries, bool createMostFeasibleSolution, CancellationToken cancelToken) {
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[15555] | 65 | var weights = problemInstance.Weights;
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| 66 | var distances = problemInstance.Distances;
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[15558] | 67 | var installCosts = problemInstance.InstallationCosts;
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[15504] | 68 | var demands = problemInstance.Demands;
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[15553] | 69 | var capacities = problemInstance.Capacities.ToArray();
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[15555] | 70 | var transportCosts = problemInstance.TransportationCosts;
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[15553] | 71 | var equipments = demands.Length;
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| 72 | var locations = capacities.Length;
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[7593] | 73 | int tries = 0;
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[15553] | 74 | var slack = new double[locations];
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[7593] | 75 | double minViolation = double.MaxValue;
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[15558] | 76 | int[] assignment = null;
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[15553] | 77 | int[] bestAssignment = null;
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[15555] | 78 | var F = new List<int>(equipments); // set of (initially) all facilities / equipments
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| 79 | var CF = new List<int>(equipments); // set of chosen facilities / equipments
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| 80 | var L = new List<int>(locations); // set of (initially) all locations
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[15553] | 81 | var CL_list = new List<int>(locations); // list of chosen locations
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| 82 | var CL_selected = new bool[locations]; // bool decision if location is chosen
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[15555] | 83 | var T = new List<int>(equipments); // set of facilities / equpiments that can be assigned to the set of chosen locations (CL)
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| 84 | var H = new double[locations]; // proportions for choosing locations in stage 1
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| 85 | var W = new double[equipments]; // proportions for choosing facilities in stage 2
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| 86 | var Z = new double[locations]; // proportions for choosing locations in stage 2
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[15558] | 87 |
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| 88 | for (var k = 0; k < equipments; k++) {
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| 89 | for (var h = 0; h < equipments; h++) {
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| 90 | if (k == h) continue;
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| 91 | W[k] += weights[k, h];
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| 92 | }
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| 93 | W[k] *= demands[k];
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| 94 | }
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[15555] | 95 |
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[7593] | 96 | while (maximumTries <= 0 || tries < maximumTries) {
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| 97 | cancelToken.ThrowIfCancellationRequested();
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| 98 |
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[15558] | 99 | assignment = new int[equipments];
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| 100 |
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[15555] | 101 | Array.Copy(capacities, slack, locations); // line 2 of Algorihm 2
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| 102 | CF.Clear(); // line 2 of Algorihm 2
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| 103 | Array.Clear(CL_selected, 0, locations); // line 2 of Algorihm 2
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| 104 | CL_list.Clear(); // line 2 of Algorihm 2
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| 105 | T.Clear(); // line 2 of Algorihm 2
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[7593] | 106 |
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[15555] | 107 | F.Clear(); F.AddRange(Enumerable.Range(0, equipments)); // line 2 of Algorihm 2
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| 108 | L.Clear(); L.AddRange(Enumerable.Range(0, locations)); // line 2 of Algorihm 2
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[15553] | 109 |
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[15558] | 110 | Array.Clear(H, 0, H.Length);
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| 111 |
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[15555] | 112 | double threshold = 1.0; // line 3 of Algorithm 2
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| 113 | do { // line 4 of Algorithm 2
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| 114 | if (L.Count > 0 && random.NextDouble() < threshold) { // line 5 of Algorithm 2
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| 115 | // H is the proportion that a location is chosen
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| 116 | // The paper doesn't mention what happens if the candidate list CL
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| 117 | // does not contain an element in which case according to the formula
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| 118 | // all H_k elements would be 0 which would be equal to random selection
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[15558] | 119 | var HH = L.Select(x => H[x]);
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[15555] | 120 | int l = L.SampleProportional(random, 1, HH, false, false).Single(); // line 6 of Algorithm 2
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| 121 | L.Remove(l); // line 7 of Algorithm 2
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| 122 | CL_list.Add(l); // line 7 of Algorithm 2
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| 123 | CL_selected[l] = true; // line 7 of Algorithm 2
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[15558] | 124 | // incrementally updating location weights
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| 125 | foreach (var k in L)
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| 126 | H[k] += capacities[k] * capacities[l] / distances[k, l];
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| 127 |
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[15555] | 128 | T = new List<int>(WhereDemandEqualOrLess(F, GetMaximumSlack(slack, CL_selected), demands)); // line 8 of Algorithm 2
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[7407] | 129 | }
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[15555] | 130 | if (T.Count > 0) { // line 10 of Algorithm 2
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| 131 | // W is the proportion that an equipment is chosen
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[15558] | 132 | var WW = T.Select(x => W[x]);
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| 133 | var f = T.SampleProportional(random, 1, WW, false, false) // line 11 of Algorithm 2
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[15555] | 134 | .Single();
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| 135 | T.Remove(f); // line 12 of Algorithm 2
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| 136 | F.Remove(f); // line 12 of Algorithm 2
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| 137 | CF.Add(f); // line 12 of Algorithm 2
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| 138 | var R = WhereSlackGreaterOrEqual(CL_list, demands[f], slack).ToList(); // line 13 of Algorithm 2
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| 139 | // Z is the proportion that a location is chosen in stage 2
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[15558] | 140 | var l = R[0];
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| 141 | if (R.Count > 1) { // optimization, calculate probabilistic weights only in case |R| > 1
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| 142 | Array.Clear(Z, 0, R.Count);
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| 143 | var zk = 0;
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| 144 | foreach (var k in R) {
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| 145 | // d is an increase in fitness if f would be assigned to location k
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| 146 | var d = installCosts[f, k];
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| 147 | foreach (var i in CF) {
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| 148 | if (assignment[i] == 0) continue; // i is unassigned
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| 149 | var j = assignment[i] - 1;
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| 150 | d += transportCosts * weights[f, i] * distances[k, j];
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| 151 | }
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| 152 | foreach (var h in CL_list) {
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| 153 | if (k == h) continue;
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| 154 | Z[zk] += slack[k] * capacities[h] / (d * distances[k, h]);
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| 155 | }
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| 156 | zk++;
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[15555] | 157 | }
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[15558] | 158 | l = R.SampleProportional(random, 1, Z.Take(R.Count), false, false).Single(); // line 14 of Algorithm 2
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[15555] | 159 | }
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| 160 | assignment[f] = l + 1; // line 15 of Algorithm 2
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[7407] | 161 | slack[l] -= demands[f];
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[15555] | 162 | T = new List<int>(WhereDemandEqualOrLess(F, GetMaximumSlack(slack, CL_selected), demands)); // line 16 of Algorithm 2
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| 163 | threshold = 1.0 - (double)T.Count / Math.Max(F.Count, 1.0); // line 17 of Algorithm 2
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[7407] | 164 | }
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[15555] | 165 | } while (T.Count > 0 || L.Count > 0); // line 19 of Algorithm 2
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| 166 |
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[7593] | 167 | if (maximumTries > 0) tries++;
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[15555] | 168 |
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[15553] | 169 | if (F.Count == 0) {
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[15555] | 170 | bestAssignment = assignment.Select(x => x - 1).ToArray();
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[7593] | 171 | break;
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| 172 | } else if (createMostFeasibleSolution) {
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| 173 | // complete the solution and remember the one with least violation
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[7833] | 174 | foreach (var l in L.ToArray()) {
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[15553] | 175 | CL_list.Add(l);
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| 176 | CL_selected[l] = true;
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[7833] | 177 | L.Remove(l);
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| 178 | }
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[15553] | 179 | while (F.Count > 0) {
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| 180 | var f = F.Select((v, i) => new { Index = i, Value = v }).MaxItems(x => demands[x.Value]).SampleRandom(random);
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| 181 | var l = CL_list.MaxItems(x => slack[x]).SampleRandom(random);
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| 182 | F.RemoveAt(f.Index);
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| 183 | assignment[f.Value] = l + 1;
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| 184 | slack[l] -= demands[f.Value];
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[7593] | 185 | }
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[15504] | 186 | double violation = slack.Select(x => x < 0 ? -x : 0).Sum();
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[7593] | 187 | if (violation < minViolation) {
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[15555] | 188 | bestAssignment = assignment.Select(x => x - 1).ToArray();
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[7593] | 189 | minViolation = violation;
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| 190 | }
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| 191 | }
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[7373] | 192 | }
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| 193 |
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[15555] | 194 | if (bestAssignment == null)
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[15553] | 195 | throw new InvalidOperationException(String.Format("No solution could be found in {0} tries.", maximumTries));
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[7407] | 196 |
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[15555] | 197 | return new IntegerVector(bestAssignment);
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[7373] | 198 | }
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[7407] | 199 |
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[15504] | 200 | protected override IntegerVector CreateRandomSolution(IRandom random, GQAPInstance problemInstance) {
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| 201 | return CreateSolution(random, problemInstance,
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[7593] | 202 | MaximumTriesParameter.ActualValue.Value,
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| 203 | CreateMostFeasibleSolutionParameter.ActualValue.Value,
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| 204 | CancellationToken);
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| 205 | }
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| 206 |
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[15553] | 207 | private static IEnumerable<int> WhereDemandEqualOrLess(IEnumerable<int> facilities, double maximum, DoubleArray demands) {
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[7407] | 208 | foreach (int f in facilities) {
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| 209 | if (demands[f] <= maximum) yield return f;
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| 210 | }
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| 211 | }
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| 212 |
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[15553] | 213 | private static double GetMaximumSlack(double[] slack, bool[] CL) {
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| 214 | var max = double.MinValue;
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| 215 | for (var i = 0; i < slack.Length; i++) {
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| 216 | if (CL[i] && max < slack[i]) max = slack[i];
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| 217 | }
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| 218 | return max;
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[7407] | 219 | }
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| 220 |
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[15553] | 221 | private static IEnumerable<int> WhereSlackGreaterOrEqual(IEnumerable<int> locations, double minimum, double[] slack) {
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[7407] | 222 | foreach (int l in locations) {
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| 223 | if (slack[l] >= minimum) yield return l;
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| 224 | }
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| 225 | }
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[7373] | 226 | }
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| 227 | }
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