Allocate new vehicle if condition is met

[glazaridis]

Hi all, is there any way to allocate a new vehicle when a distance constraint C from depot to first visiting node is met?

Thank you for your time and consideration.

[Mizux]

first, I would try to find the first visit using the following code:

all_visit_locations = [2, 3, ....]
# Not sure min is defined but let's suppose it is
first_visit_cumulvar = min([distance/time_dim.CumulVar(manager.NodeToIndex(node)) for node in all_visit_location)])

Then I'll would add a constraint that the extra vehicle (of index vehicle_id) is active iff the constraint is met:

routing.solver().Add((first_visit_cumulvar >= your_constraint_C) == routing.ActiveVehicleVar(vehicle_id))

ref:

or-tools/ortools/constraint_solver/routing.h

Lines 1198 to 1202 in b77bd3a

	/// Returns the active variable of the vehicle. It will be equal to 1 iff the
	/// route of the vehicle is not empty, 0 otherwise.
	IntVar* ActiveVehicleVar(int vehicle) const {
	return vehicle_active_[vehicle];
	}

[glazaridis]

@Mizux thanks for the reply. So, in the simplest case where I have the following simple snippet from the documentation and I'm only interested in a distance constraint, how would the above code be incorporated? Note: Assume the example's content for data variable.

    # Create the routing index manager.
    manager = pywrapcp.RoutingIndexManager(len(data['distance_matrix']),
                                           data['num_vehicles'], data['depot'])

    # Create Routing Model.
    routing = pywrapcp.RoutingModel(manager)

    # Create and register a transit callback.
    def distance_callback(from_index, to_index):
        """Returns the distance between the two nodes."""
        # Convert from routing variable Index to distance matrix NodeIndex.
        from_node = manager.IndexToNode(from_index)
        to_node = manager.IndexToNode(to_index)
        return int(data['distance_matrix'][from_node][to_node])

    transit_callback_index = routing.RegisterTransitCallback(distance_callback)

    # Define cost of each arc.
    routing.SetArcCostEvaluatorOfAllVehicles(transit_callback_index)

    # Add Capacity constraint.
    def demand_callback(from_index):
        """Returns the demand of the node."""
        # Convert from routing variable Index to demands NodeIndex.
        from_node = manager.IndexToNode(from_index)
        return round(data['demands'][from_node])

    demand_callback_index = routing.RegisterUnaryTransitCallback(
        demand_callback)
    routing.AddDimensionWithVehicleCapacity(
        demand_callback_index,
        0,  # null capacity slack
        data['vehicle_capacities'],  # vehicle maximum capacities
        True,  # start cumul to zero
        'Capacity')