VRP with same vehicles constraints.

same_vehicle.py

#!/usr/bin/env python3
"""Vehicles Routing Problem (VRP)."""

import sys
from ortools.constraint_solver import routing_enums_pb2, pywrapcp

# Model
dim_name = 'Dimension'

def duration_callback(from_index, to_index):
    from_node = manager.IndexToNode(from_index)
    to_node = manager.IndexToNode(to_index)
    return 2


manager = pywrapcp.RoutingIndexManager(9, 2, 0)
routing = pywrapcp.RoutingModel(manager)
transit_callback_index = routing.RegisterTransitCallback(duration_callback)
routing.SetArcCostEvaluatorOfAllVehicles(transit_callback_index)
MAX_ROUTE_TIME = 400
routing.AddDimension(transit_callback_index, 0, MAX_ROUTE_TIME, True, dim_name)
time_dimension = routing.GetDimensionOrDie(dim_name)

pickups_deliveries = [
        (1, 2),
        (3, 4),
        (5, 6),
        (7, 8)
        ]

for pickup, delivery in pickups_deliveries:
    pickup_index = manager.NodeToIndex(pickup)
    delivery_index = manager.NodeToIndex(delivery)
    routing.AddPickupAndDelivery(pickup_index, delivery_index)
    routing.solver().Add(routing.VehicleVar(pickup_index) == routing.VehicleVar(delivery_index))
    routing.solver().Add(time_dimension.CumulVar(pickup_index) <= time_dimension.CumulVar(delivery_index))

start_0 = routing.Start(0)
start_1 = routing.Start(1)
pickup_1 = manager.NodeToIndex(1)
pickup_3 = manager.NodeToIndex(3)
pickup_5 = manager.NodeToIndex(5)

# P1 == P3
active_p1_p3 = routing.ActiveVar(pickup_1) * routing.ActiveVar(pickup_3)
#active_p1_p3 = 1
routing.solver().Add(
        active_p1_p3 * routing.VehicleVar(pickup_1) ==
        active_p1_p3 * routing.VehicleVar(pickup_3))

# P1 != P5
active_p1_p5 = routing.ActiveVar(pickup_1) * routing.ActiveVar(pickup_5)
#active_p1_p5 = 1
routing.solver().Add(
        active_p1_p5 * (routing.VehicleVar(pickup_1) - routing.VehicleVar(pickup_5)) !=
        (1 - active_p1_p5))

# S0 == P5
active_s0_p5 = routing.ActiveVar(start_0) * routing.ActiveVar(pickup_5)
#active_s0_p5 = 1
routing.solver().Add(
        active_s0_p5 * routing.VehicleVar(start_0) ==
        active_s0_p5 * routing.VehicleVar(pickup_5))

# S1 == P1
active_s1_p1 = routing.ActiveVar(start_1) * routing.ActiveVar(pickup_1)
#active_s1_p1 = 1
routing.solver().Add(
        active_s1_p1 * routing.VehicleVar(start_1) ==
        active_s1_p1 * routing.VehicleVar(pickup_1))

for node in range(1, 9):
    routing.AddDisjunction([manager.NodeToIndex(node)], 1000)

search_parameters = pywrapcp.DefaultRoutingSearchParameters()
search_parameters.log_search = True

search_parameters.first_solution_strategy = routing_enums_pb2.FirstSolutionStrategy.ALL_UNPERFORMED
#search_parameters.first_solution_strategy = routing_enums_pb2.FirstSolutionStrategy.AUTOMATIC

search_parameters.local_search_metaheuristic = routing_enums_pb2.LocalSearchMetaheuristic.GUIDED_LOCAL_SEARCH
#search_parameters.lns_time_limit.seconds = 1
search_parameters.time_limit.seconds = 5
solution = routing.SolveWithParameters(search_parameters)

if solution == None:
    print("No solution found !")
    sys.exit(0)
print(f"objective: {solution.ObjectiveValue()}")
# Display dropped nodes.
dropped_nodes = 'Dropped nodes:'
for node in range(routing.Size()):
    if routing.IsStart(node) or routing.IsEnd(node):
        continue
    if solution.Value(routing.NextVar(node)) == node:
        dropped_nodes += ' {}'.format(manager.IndexToNode(node))
print(dropped_nodes)

for vehicle_id in range(manager.GetNumberOfVehicles()):
    print(f"Vehicle {vehicle_id}:")
    index = routing.Start(vehicle_id)
    node = manager.IndexToNode(index)
    while not routing.IsEnd(index):
        previous_node = node
        previous_index = index
        index = solution.Value(routing.NextVar(index))
        node = manager.IndexToNode(index)
        nmap = node
        print(f"{previous_node} -> {node}")

zz.md

Possible output:

./same_vehicle.py
...
objective: 20
Dropped nodes:
Vehicle 0:
0 -> 7
7 -> 8
8 -> 5
5 -> 6
6 -> 0
Vehicle 1:
0 -> 1
1 -> 2
2 -> 3
3 -> 4
4 -> 0

Estimados, me podrán ayudar con un código de Python usando OR Tools, para resolver un problema de ruteo de varios camiones con dos depositos de partida.
Tendrán, algo para ver como se hace.
Gracias