Adding a hard and soft upper bound constraint of number of locations to visit (VRP)

Question

I went through the Vehicle Routing Problem example and was able to replicate it. On the example, there is a constraint added for vehicle maximum distance as shown below:

dimension_name = 'Distance'
routing.AddDimension(
    transit_callback_index,
    0,  # no slack
    3000,  # vehicle maximum travel distance
    True,  # start cumul to zero
    dimension_name)
distance_dimension = routing.GetDimensionOrDie(dimension_name)
distance_dimension.SetGlobalSpanCostCoefficient(100)

Similar to the CVRP, how do I modify the constraint for the number of locations that each vehicle can visit (either global or by each vehicle) rather than the demand?

Answer 1

Crossposted from: Stack Overflow

The idea is to create another dimension ('visit') that is incremented by 1 on each visit. Then use SetCumulVarSoftUpperBound on the cumul variable of that dimension at the end of each route.