static void Main(string[] args)
{
if (args.Length < 1)
{
Console.Out.WriteLine("Usage: tune_cs filename");
return;
}
try {
GRBEnv env = new GRBEnv();
// Read model from file
GRBModel model = new GRBModel(env, args[0]);
// Set the TuneResults parameter to 1
model.GetEnv().Set(GRB.IntParam.TuneResults, 1);
// Tune the model
model.Tune();
// Get the number of tuning results
int resultcount = model.Get(GRB.IntAttr.TuneResultCount);
if (resultcount > 0)
{
// Load the tuned parameters into the model's environment
model.GetTuneResult(0);
// Write the tuned parameters to a file
model.Write("tune.prm");
// Solve the model using the tuned parameters
model.Optimize();
}
// Dispose of model and environment
model.Dispose();
env.Dispose();
} catch (GRBException e) {
Console.WriteLine("Error code: " + e.ErrorCode + ". " + e.Message);
}
}
public Dictionary <string, string> Solve(bool tune, bool debug, string tuneOutputFile = null, string paramFile = null)
{
var times = new Dictionary <string, string>();
var totalTime = Utils.TimeAction(() =>
{
try
{
// Create an empty environment, set options and start
GRBEnv env = new GRBEnv(true);
// Use gurobi's parameter reader to load the best file
if (paramFile != null)
{
env.ReadParams(paramFile);
}
if (!debug)
{
env.Set(GRB.IntParam.OutputFlag, 0);
}
env.Start();
// Create empty model
GRBModel model = new GRBModel(env);
(var grbSeated, var addDecisionVariableTime) = Utils.TimeFunction(() => AddSeatedBinaryVariables(model), "Add Decision Variables");
var addConstraintsTime = Utils.TimeAction(() => AddContraints(model, grbSeated), "Add Constraints");
var addObjectiveTime = Utils.TimeAction(() => AddObjective(model, grbSeated), "Add Objective");
var optimizeTime = Utils.TimeAction(() => model.Optimize(), "Optimizing");
if (tune)
{
model.Tune();
model.GetTuneResult(0);
model.Write(tuneOutputFile);
}
SeatGroups(grbSeated);
// Dispose of model and env
model.Dispose();
env.Dispose();
times.Add("Add Decision Variables", addDecisionVariableTime);
times.Add("Add Constraints", addConstraintsTime);
times.Add("Add Objective", addObjectiveTime);
times.Add("Optimizing", optimizeTime);
}
catch (GRBException e)
{
Console.WriteLine("Error code: " + e.ErrorCode + ". " + e.Message);
throw e;
}
}, "Total");
times.Add("Total", totalTime);
return(times);
}
public static Graph RunSolver(Graph graph)
{
GRBEnv env = new GRBEnv();
env.Set(GRB.IntParam.OutputFlag, 0);
env.Set(GRB.IntParam.LogToConsole, 0);
env.Set(GRB.IntParam.Presolve, 2);
env.Set(GRB.DoubleParam.Heuristics, 0.0);
GRBModel model = new GRBModel(env);
GRBVar[] variables = new GRBVar[graph.NumberOfEdges];
model.SetCallback(new LPSolverCallback());
Dictionary<Edge, GRBVar> edgeVars = new Dictionary<Edge, GRBVar>();
// Add variables to the LP model
for (int i = 0; i < graph.NumberOfEdges; i++)
{
variables[i] = model.AddVar(0.0, 1.0, 0.0, GRB.BINARY, "x_" + i);
edgeVars.Add(graph.Edges[i], variables[i]);
}
model.Update();
// Add constraints to the LP model
Console.Write("\rRunning LP. Creating constraints...\r");
//var nonTerminals = graph.Vertices.Except(graph.Terminals).ToList();
ulong conNr = 0;
//var terminalCombinations = new List<List<Vertex>>();
// Assume, without loss of generality, that Terminals[0] is the root, and thus is always included
int rootNr = 1;
foreach (var rootTerminal in graph.Terminals)
//var rootTerminal = graph.Terminals[0];
{
Console.Write("\rRunning LP. Creating constraints... {0}/{1}\r", rootNr, graph.Terminals.Count);
foreach (var combination in GetBFS(graph, rootTerminal))
{
var nodes = combination.ToList(); //new HashSet<Vertex>(combination);
if (nodes.Count == graph.NumberOfVertices || graph.Terminals.All(nodes.Contains))
continue;
//Debug.WriteLine("Combination: {0}", string.Join(" ", nodes));
//for (int i = 1; i <= nodes.Count; i++)
{
var edges = nodes//.Take(i)
.SelectMany(graph.GetEdgesForVertex)
.Distinct()
.Where(x => x.WhereOne(y => !nodes.Contains(y)));
GRBLinExpr expression = 0;
foreach (var edge in edges)
expression.AddTerm(1, edgeVars[edge]);
model.AddConstr(expression >= 1.0, "subset_" + conNr);
conNr++;
if (conNr % 100000 == 0)
{
//model = model.Presolve(); //Pre-solve the model every 1000 constraints.
int constrBefore = model.GetConstrs().Length, varsBefore = model.GetVars().Length;
Debug.WriteLine("Presolve called.");
var presolved = model.Presolve();
Debug.WriteLine("Model has {0} constraints, {1} variables. Presolve has {2} constraints, {3} variables",
constrBefore, varsBefore, presolved.GetConstrs().Length, presolved.GetVars().Length);
}
}
}
//Debug.WriteLine(" ");
//Debug.WriteLine(" ");
rootNr++;
}
//terminalCombinations.Add(new List<Vertex>(new[] { graph.Terminals[0] }));
//for (int j = 1; j < graph.Terminals.Count - 1; j++)
// terminalCombinations.AddRange(new Combinations<Vertex>(graph.Terminals.Skip(1), j).Select(combination => combination.Union(new[] { graph.Terminals[0] }).ToList()));
//long nonTerminalSetsDone = 0;
//long nonTerminalSets = 0;
//for (int i = 0; i <= nonTerminals.Count; i++)
// nonTerminalSets += Combinations<Vertex>.NumberOfCombinations(nonTerminals.Count, i);
//for (int i = 0; i <= nonTerminals.Count; i++)
//{
// foreach (var nonTerminalSet in new Combinations<Vertex>(nonTerminals, i))
// {
// foreach (var nodes in (from a in terminalCombinations
// select new HashSet<Vertex>(a.Union(nonTerminalSet))))
// {
// var edges = nodes.SelectMany(graph.GetEdgesForVertex)
// .Distinct()
// .Where(x => x.WhereOne(y => !nodes.Contains(y)));
// GRBLinExpr expression = 0;
// foreach (var edge in edges)
// expression.AddTerm(1, edgeVars[edge]);
// model.AddConstr(expression >= 1.0, "subset_" + conNr);
// conNr++;
// }
// nonTerminalSetsDone++;
// if (nonTerminalSetsDone % 100 == 0)
// Console.Write("\rRunning LP. Creating constraints... {0}/{1} ({2:0.000}%)\r", nonTerminalSetsDone, nonTerminalSets, nonTerminalSetsDone * 100.0 / nonTerminalSets);
// }
//}
// Solve the LP model
Console.Write("\rRunning LP. Creating objective & updating... \r");
GRBLinExpr objective = new GRBLinExpr();
for (int i = 0; i < graph.NumberOfEdges; i++)
objective.AddTerm(graph.Edges[i].Cost, variables[i]);
model.SetObjective(objective, GRB.MINIMIZE);
Console.Write("\rRunning LP. Tuning... \r");
model.Tune();
Debug.WriteLine("Presolve called.");
model.Presolve();
Console.Write("\rRunning LP. Solving... \r");
Debug.WriteLine("Optimize called.");
model.Optimize();
Graph solution = graph.Clone();
HashSet<Edge> includedEdges = new HashSet<Edge>();
for (int i = 0; i < solution.NumberOfEdges; i++)
{
var value = variables[i].Get(GRB.DoubleAttr.X);
if (value == 1)
includedEdges.Add(solution.Edges[i]);
}
foreach (var edge in solution.Edges.ToList())
if (!includedEdges.Contains(edge))
solution.RemoveEdge(edge);
Console.Write("\r \r");
return solution;
}