1 | #region License Information
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2 | /* HeuristicLab
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3 | * Copyright (C) 2002-2018 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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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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22 | using System;
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23 | using System.Collections.Generic;
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24 | using System.IO;
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25 | using System.Linq;
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26 | using System.Reflection;
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27 | using System.Threading;
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28 | using Google.OrTools.LinearSolver;
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29 | using HeuristicLab.Common;
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30 | using HeuristicLab.Core;
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31 | using HeuristicLab.Data;
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32 | using HeuristicLab.Optimization;
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33 | using HeuristicLab.Parameters;
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34 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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35 |
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36 | namespace HeuristicLab.MathematicalOptimization.LinearProgramming {
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37 |
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38 | [StorableClass]
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39 | public class LinearSolver : ParameterizedNamedItem, ILinearSolver, IDisposable {
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40 |
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41 | [Storable]
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42 | protected IValueParameter<EnumValue<ProblemType>> problemTypeParam;
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43 |
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44 | protected Solver solver;
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45 |
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46 | [Storable]
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47 | protected IFixedValueParameter<TextValue> solverSpecificParametersParam;
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48 |
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49 | public LinearSolver() {
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50 | Parameters.Add(problemTypeParam =
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51 | new ValueParameter<EnumValue<ProblemType>>(nameof(ProblemType), new EnumValue<ProblemType>()));
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52 | Parameters.Add(solverSpecificParametersParam =
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53 | new FixedValueParameter<TextValue>(nameof(SolverSpecificParameters), new TextValue()));
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54 | }
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55 |
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56 | [StorableConstructor]
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57 | protected LinearSolver(bool deserializing)
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58 | : base(deserializing) {
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59 | }
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60 |
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61 | protected LinearSolver(LinearSolver original, Cloner cloner)
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62 | : base(original, cloner) {
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63 | problemTypeParam = cloner.Clone(original.problemTypeParam);
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64 | solverSpecificParametersParam = cloner.Clone(original.solverSpecificParametersParam);
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65 | }
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66 |
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67 | public double DualTolerance { get; set; } = MPSolverParameters.kDefaultDualTolerance;
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68 |
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69 | public string ExportModel { get; set; }
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70 |
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71 | public bool Incrementality { get; set; } =
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72 | MPSolverParameters.kDefaultIncrementality == MPSolverParameters.INCREMENTALITY_ON;
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73 |
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74 | public LpAlgorithmValues LpAlgorithm { get; set; }
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75 |
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76 | public bool Presolve { get; set; } = MPSolverParameters.kDefaultPresolve == MPSolverParameters.PRESOLVE_ON;
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77 |
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78 | public double PrimalTolerance { get; set; } = MPSolverParameters.kDefaultPrimalTolerance;
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79 |
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80 | public ProblemType ProblemType {
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81 | get => problemTypeParam.Value.Value;
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82 | set => problemTypeParam.Value.Value = value;
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83 | }
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84 |
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85 | public double RelativeGapTolerance { get; set; } = MPSolverParameters.kDefaultRelativeMipGap;
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86 |
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87 | public bool Scaling { get; set; }
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88 |
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89 | public string SolverSpecificParameters {
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90 | get => solverSpecificParametersParam.Value.Value;
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91 | set => solverSpecificParametersParam.Value.Value = value;
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92 | }
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93 |
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94 | public virtual bool SupportsPause => true;
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95 | public virtual bool SupportsStop => true;
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96 | public virtual TimeSpan TimeLimit { get; set; } = TimeSpan.Zero;
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97 | protected virtual OptimizationProblemType OptimizationProblemType { get; }
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98 |
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99 | public override IDeepCloneable Clone(Cloner cloner) => new LinearSolver(this, cloner);
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100 |
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101 | public void Dispose() => solver?.Dispose();
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102 |
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103 | public bool ExportAsLp(string fileName, bool obfuscated = false) {
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104 | var lpFormat = solver?.ExportModelAsLpFormat(obfuscated);
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105 | if (string.IsNullOrEmpty(lpFormat))
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106 | return false;
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107 | File.WriteAllText(fileName, lpFormat);
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108 | return true;
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109 | }
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110 |
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111 | public bool ExportAsMps(string fileName, bool fixedFormat = false, bool obfuscated = false) {
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112 | var mpsFormat = solver?.ExportModelAsMpsFormat(fixedFormat, obfuscated);
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113 | if (string.IsNullOrEmpty(mpsFormat))
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114 | return false;
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115 | File.WriteAllText(fileName, mpsFormat);
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116 | return true;
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117 | }
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118 |
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119 | public bool ExportAsProto(string fileName, ProtoWriteFormat writeFormat = ProtoWriteFormat.ProtoBinary) =>
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120 | solver != null && solver.ExportModelAsProtoFormat(fileName, (int)writeFormat);
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121 |
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122 | public SolverResponseStatus ImportFromMps(string fileName, bool? fixedFormat) => solver == null
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123 | ? SolverResponseStatus.Abnormal
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124 | : (SolverResponseStatus)solver.ImportModelFromMpsFormat(fileName, fixedFormat.HasValue, fixedFormat ?? false);
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125 |
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126 | public SolverResponseStatus ImportFromProto(string fileName) => solver == null
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127 | ? SolverResponseStatus.Abnormal
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128 | : (SolverResponseStatus)solver.ImportModelFromProtoFormat(fileName);
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129 |
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130 | public bool InterruptSolve() => solver?.InterruptSolve() ?? false;
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131 |
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132 | public virtual void Reset() {
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133 | solver?.Dispose();
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134 | solver = null;
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135 | }
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136 |
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137 | public virtual void Solve(ILinearProgrammingProblemDefinition problemDefintion, ref TimeSpan executionTime,
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138 | ResultCollection results, CancellationToken cancellationToken) =>
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139 | Solve(problemDefintion, ref executionTime, results);
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140 |
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141 | public virtual void Solve(ILinearProgrammingProblemDefinition problemDefinition, ref TimeSpan executionTime,
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142 | ResultCollection results) =>
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143 | Solve(problemDefinition, results, TimeLimit);
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144 |
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145 | public virtual void Solve(ILinearProgrammingProblemDefinition problemDefinition, ResultCollection results,
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146 | TimeSpan timeLimit) {
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147 | if (solver == null) {
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148 | solver = CreateSolver(OptimizationProblemType);
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149 | problemDefinition.BuildModel(solver);
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150 | }
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151 |
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152 | if (timeLimit > TimeSpan.Zero) {
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153 | solver.SetTimeLimit((long)timeLimit.TotalMilliseconds);
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154 | } else {
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155 | solver.SetTimeLimit(0);
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156 | }
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157 |
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158 | ResultStatus resultStatus;
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159 |
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160 | using (var parameters = new MPSolverParameters()) {
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161 | parameters.SetDoubleParam(MPSolverParameters.RELATIVE_MIP_GAP, RelativeGapTolerance);
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162 | parameters.SetDoubleParam(MPSolverParameters.PRIMAL_TOLERANCE, PrimalTolerance);
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163 | parameters.SetDoubleParam(MPSolverParameters.DUAL_TOLERANCE, DualTolerance);
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164 | parameters.SetIntegerParam(MPSolverParameters.PRESOLVE,
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165 | Presolve ? MPSolverParameters.PRESOLVE_ON : MPSolverParameters.PRESOLVE_OFF);
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166 | parameters.SetIntegerParam(MPSolverParameters.LP_ALGORITHM, (int)LpAlgorithm);
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167 | parameters.SetIntegerParam(MPSolverParameters.INCREMENTALITY,
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168 | Incrementality ? MPSolverParameters.INCREMENTALITY_ON : MPSolverParameters.INCREMENTALITY_OFF);
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169 | parameters.SetIntegerParam(MPSolverParameters.SCALING,
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170 | Scaling ? MPSolverParameters.SCALING_ON : MPSolverParameters.SCALING_OFF);
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171 |
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172 | if (!solver.SetSolverSpecificParametersAsString(SolverSpecificParameters))
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173 | throw new ArgumentException("Solver specific parameters could not be set.");
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174 |
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175 | if (!string.IsNullOrWhiteSpace(ExportModel)) {
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176 | var fileInfo = new FileInfo(ExportModel);
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177 |
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178 | if (!fileInfo.Directory?.Exists ?? false) {
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179 | Directory.CreateDirectory(fileInfo.Directory.FullName);
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180 | }
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181 |
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182 | bool exportSuccessful;
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183 | switch (fileInfo.Extension) {
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184 | case ".lp":
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185 | exportSuccessful = ExportAsLp(ExportModel);
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186 | break;
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187 |
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188 | case ".mps":
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189 | exportSuccessful = ExportAsMps(ExportModel);
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190 | break;
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191 |
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192 | case ".prototxt":
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193 | exportSuccessful = ExportAsProto(ExportModel, ProtoWriteFormat.ProtoText);
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194 | break;
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195 |
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196 | case ".bin": // remove file extension as it is added by OR-Tools
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197 | exportSuccessful = ExportAsProto(Path.ChangeExtension(ExportModel, null));
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198 | break;
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199 |
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200 | default:
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201 | throw new NotSupportedException("File format selected to export model is not supported.");
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202 | }
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203 | }
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204 |
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205 | // TODO: show warning if file export didn't work (if exportSuccessful is false)
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206 |
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207 | resultStatus = (ResultStatus)solver.Solve(parameters);
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208 | }
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209 |
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210 | var objectiveValue = solver.Objective()?.Value();
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211 |
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212 | problemDefinition.Analyze(solver, results);
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213 | results.AddOrUpdateResult("ResultStatus", new EnumValue<ResultStatus>(resultStatus));
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214 | results.AddOrUpdateResult("BestObjectiveValue", new DoubleValue(objectiveValue ?? double.NaN));
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215 |
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216 | if (solver.IsMIP()) {
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217 | var objectiveBound = solver.Objective()?.BestBound();
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218 | var absoluteGap = objectiveValue.HasValue && objectiveBound.HasValue
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219 | ? Math.Abs(objectiveBound.Value - objectiveValue.Value)
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220 | : (double?)null;
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221 | // https://www.ibm.com/support/knowledgecenter/SSSA5P_12.7.1/ilog.odms.cplex.help/CPLEX/Parameters/topics/EpGap.html
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222 | var relativeGap = absoluteGap.HasValue && objectiveValue.HasValue
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223 | ? absoluteGap.Value / (1e-10 + Math.Abs(objectiveValue.Value))
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224 | : (double?)null;
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225 |
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226 | results.AddOrUpdateResult("BestObjectiveBound", new DoubleValue(objectiveBound ?? double.NaN));
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227 | results.AddOrUpdateResult("AbsoluteGap", new DoubleValue(absoluteGap ?? double.NaN));
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228 | results.AddOrUpdateResult("RelativeGap", new PercentValue(relativeGap ?? double.NaN));
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229 | }
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230 |
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231 | results.AddOrUpdateResult("NumberOfConstraints", new IntValue(solver.NumConstraints()));
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232 | results.AddOrUpdateResult("NumberOfVariables", new IntValue(solver.NumVariables()));
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233 |
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234 | if (solver.IsMIP() && solver.Nodes() >= 0) {
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235 | results.AddOrUpdateResult(nameof(solver.Nodes), new DoubleValue(solver.Nodes()));
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236 | }
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237 |
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238 | if (solver.Iterations() >= 0) {
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239 | results.AddOrUpdateResult(nameof(solver.Iterations), new DoubleValue(solver.Iterations()));
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240 | }
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241 |
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242 | results.AddOrUpdateResult(nameof(solver.SolverVersion), new StringValue(solver.SolverVersion()));
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243 | }
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244 |
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245 | protected virtual Solver CreateSolver(OptimizationProblemType optimizationProblemType, string libraryName = null) {
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246 | if (!string.IsNullOrEmpty(libraryName) && !File.Exists(libraryName)) {
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247 | var paths = new List<string> {
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248 | Path.GetDirectoryName(new Uri(Assembly.GetExecutingAssembly().CodeBase).LocalPath)
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249 | };
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250 | var path = Environment.GetEnvironmentVariable("PATH");
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251 | if (path != null)
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252 | paths.AddRange(path.Split(';'));
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253 | if (!paths.Any(p => File.Exists(Path.Combine(p, libraryName))))
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254 | throw new FileNotFoundException($"Could not find library {libraryName} in PATH.", libraryName);
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255 | }
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256 |
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257 | try {
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258 | solver = new Solver(Name, (int)optimizationProblemType, libraryName ?? string.Empty);
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259 | } catch {
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260 | throw new InvalidOperationException($"Could not create {optimizationProblemType}.");
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261 | }
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262 |
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263 | if (solver == null)
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264 | throw new InvalidOperationException($"Could not create {optimizationProblemType}.");
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265 |
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266 | solver.SuppressOutput();
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267 | return solver;
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268 | }
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269 | }
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270 | }
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