grid.VehicleType

class grid.VehicleType(id, count=1, capacity=None, start_node=None, end_node=None)

Bases: object

Definition of a homogeneous group of vehicles sharing the same parameters.

A model may contain several vehicle types, each with its own count, capacity, permitted depots, and user-defined variables.

Parameters:

• id (int) – Unique identifier of the vehicle type.

• count (int) – Number of vehicles of this type available.

• capacity (dict[str, float] | int | float) – Vehicle capacity. Scalar for single-commodity, dict mapping commodity name to per-commodity capacity for multi-commodity problems.

• start_node (int) – Id of the node where vehicles of this type start.

• end_node (int) – Id of the node where vehicles of this type must end.

variables

Decision variables registered on this vehicle type via add_integer_var(), add_float_var(), add_nodes_set_var().

Type:

list of Var

Examples

>>> import grid
>>> model = grid.RoutingModel()
>>> vehicle = model.add_vehicle_type(id=0, count=2, capacity=10)
>>> vehicle.count
2
>>> load = vehicle.add_integer_var(initial_value=10)
>>> load
Var_0

__init__(id, count=1, capacity=None, start_node=None, end_node=None)

Parameters:

• id (int)

• count (int)

• capacity (dict[str, float] | int | float)

• start_node (int)

• end_node (int)

Methods

__init__(id[, count, capacity, start_node, ...])
add_float_var(initial_value[, preference])	Create a float decision variable bound to this vehicle type.
add_integer_var(initial_value[, preference])	Create an integer decision variable bound to this vehicle type.
add_nodes_set_var(initial_value)	Create a set decision variable bound to this vehicle type.

add_float_var(initial_value, preference=None)

Create a float decision variable bound to this vehicle type.

Parameters:

• initial_value (float) – Initial value of the variable at the start of the route.

• preference (Literal['low', 'high', None]) – Solver hint indicating whether smaller or larger values should be preferred. None leaves the search neutral.

Returns:

The newly created variable.

Return type:

Var

Examples

>>> import grid
>>> model = grid.RoutingModel()
>>> vehicle = model.add_vehicle_type(id=0, count=1, capacity=10)
>>> battery = vehicle.add_float_var(initial_value=100.0, preference="high")
>>> battery.preference
'high'
>>> battery.type
'float'

add_integer_var(initial_value, preference=None)

Create an integer decision variable bound to this vehicle type.

Parameters:

• initial_value (int) – Initial value of the variable at the start of the route.

• preference (Literal['low', 'high', None]) – Solver hint indicating whether smaller or larger values should be preferred. None leaves the search neutral.

Returns:

The newly created variable.

Return type:

Var

Examples

>>> import grid
>>> model = grid.RoutingModel()
>>> vehicle = model.add_vehicle_type(id=0, count=1, capacity=10)
>>> load = vehicle.add_integer_var(initial_value=10)
>>> load.initial_value
10
>>> load.type
'integer'

add_nodes_set_var(initial_value)

Create a set decision variable bound to this vehicle type.

Used to track sets of node ids over the route (e.g. unvisited or visited nodes).

Parameters:

initial_value (set | list) – Initial contents of the set at the start of the route.

Returns:

The newly created set variable.

Return type:

SetVar

Examples

>>> import grid
>>> model = grid.RoutingModel()
>>> vehicle = model.add_vehicle_type(id=0, count=1, capacity=10)
>>> stations = vehicle.add_nodes_set_var(initial_value={3, 4})
>>> sorted(stations.initial_value)
[3, 4]