Google ortools - 赋能车辆路由pb

Question

The problem with the following code is :

即使我只有 10 个地点要送货，并且在位置 0 设置了一个站点，在这个例子中，车辆 1,2,3,4 似乎在位置 10,11,12,13 有站点.这些位置不存在。我拥有的 10 个编号为 0-9。

On the other hand the business logic seems to be OK :

因为我分离了离开车站的成本和返回车站的成本（价值 10），所以我得到了预期的结果：104。城市之间只有 4 次行程不包括车站。

Is this a bug in Google or-tools ?

public static void Main(string[] args)
{
    new CVRP().Solve(10);
}

private class RandomManhattan : NodeEvaluator2
{
    public override long Run(int first_index, int second_index)
    {
        if (first_index == 0 || second_index == 0)
            return 10;
        return 1;
    }
};

private class Demand : NodeEvaluator2
{
    public override long Run(int first_index, int second_index)
    {
        return 1;
    }
};

private void Solve(int locations)
{
    var nr_vehicle = 5;
    var routing = new RoutingModel(locations, nr_vehicle, new[] {0, 0, 0, 0, 0}, new[] {0, 0, 0, 0, 0});
    Console.WriteLine("Depot : " + routing.GetDepot());

    NodeEvaluator2 demandCallback = new Demand();
    routing.AddDimension(demandCallback, 0, 3, true, "capacity");

    var distances = new RandomManhattan();
    routing.SetCost(distances);

    var searchParameters =
        RoutingModel.DefaultSearchParameters();
    searchParameters.FirstSolutionStrategy =
        FirstSolutionStrategy.Types.Value.PathCheapestArc;

    var solution = routing.SolveWithParameters(searchParameters);


    if (solution != null)
    {
        var output = "Total cost: " + solution.ObjectiveValue() + "\n";
        // Dropped orders
        var dropped = "";
        for (var order = 0; order < locations; ++order)
        {
            if (solution.Value(routing.NextVar(order)) == order)
            {
                dropped += " " + order;
            }
        }
        if (dropped.Length > 0)
        {
            output += "Dropped orders:" + dropped + "\n";
        }
        // Routes
        for (var vehicle = 0; vehicle < nr_vehicle; ++vehicle)
        {
            var route = "Vehicle " + vehicle + ": ";
            var order = routing.Start(vehicle);
            if (routing.IsEnd(solution.Value(routing.NextVar(order))))
            {
                route += "Empty";
            }
            else
            {
                for (; !routing.IsEnd(order); order = solution.Value(routing.NextVar(order)))
                {
                    var local_load = routing.CumulVar(order, "capacity");
                    route += order + " Load(" + solution.Value(local_load) + ") -> ";
                }
                if (route.Length > 0)
                    route = route + "0";
            }
            output += route + "\n";
        }
        Console.WriteLine(output);
    }
}

Answer 1

您必须在

中包装订单

route += order + " Load(" + solution.Value(local_load) + ") -> ";

里面model.IndexToNode（顺序），像这样

route += model.IndexToNode(order) + " Load(" + solution.Value(local_load) + ") -> ";

Google ortools - 赋能车辆路由pb

Google ortools - capacitated vehicle routing pb

c#

or-tools