如何在 Google OR-Tools Route Optimization 中限制每辆车的位置数量

Question

我已经实现了用于路线优化的 Or-Tools。它工作正常。只有一件事我想达到每辆车的位置限制数量。例如，为每辆车定义最多两 (2) 个位置。

我尝试实施容量限制，但它不起作用。我还尝试实现 SetSpanUpperBoundForVehicle 函数，在这种情况下，解决方案对象为空。

这是我的代码

RoutingDimension timeDimension = routing.GetMutableDimension("Time");
            timeDimension.SetSpanUpperBoundForVehicle(2, 0);
            timeDimension.SetSpanUpperBoundForVehicle(2, 1);
            timeDimension.SetSpanUpperBoundForVehicle(2, 2);

我如何限制这条路线的数量？请帮忙

Answer 1

只需创建一个计数器维度，在每个位置加 1，然后将每辆车的容量限制为允许的最大位置数。

例如重复使用 vrp.py 个示例并添加：

   # Create counter
    def counter_callback(from_index):
        """Returns 1 for any locations except depot."""
        # Convert from routing variable Index to user NodeIndex.
        from_node = manager.IndexToNode(from_index)
        return 1 if (from_node != 0) else 0;

    counter_callback_index = routing.RegisterUnaryTransitCallback(counter_callback)

    routing.AddDimensionWithVehicleCapacity(
        counter_callback_index,
        0,  # null slack
        [4,5,4,6],  # maximum locations per vehicle
        True,  # start cumul to zero
        'Counter')

可能的输出：

%python vrp.py
Objective: 6780
Route for vehicle 0:
 0 -> 7 -> 0
Distance of the route: 388m

Route for vehicle 1:
 0 -> 14 -> 16 -> 15 -> 3 -> 4 -> 0
Distance of the route: 2716m

Route for vehicle 2:
 0 -> 13 -> 12 -> 11 -> 1 -> 0
Distance of the route: 1804m

Route for vehicle 3:
 0 -> 5 -> 8 -> 6 -> 2 -> 10 -> 9 -> 0
Distance of the route: 1872m

Total Distance of all routes: 6780m

如您所见，路由遵守 4, 5, 4, 6 位置限制。

注：对于C#的语法，几乎是一样的见 https://github.com/google/or-tools/blob/stable/ortools/constraint_solver/samples/VrpCapacity.cs 和 https://github.com/google/or-tools/blob/stable/ortools/constraint_solver/samples/VrpCapacity.csproj

如何在 Google OR-Tools Route Optimization 中限制每辆车的位置数量

How to limit number of locations for each vehicle in Google OR-Tools Route Optimization

c#

or-tools