1#!/usr/bin/env python3
2# Copyright 2010-2021 Google LLC
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7#     http://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
14# [START program]
15"""Capacited Vehicles Routing Problem (CVRP)."""
16
17# [START import]
18from ortools.constraint_solver import routing_enums_pb2
19from ortools.constraint_solver import pywrapcp
20# [END import]
21
22
23# [START data_model]
24def create_data_model():
25    """Stores the data for the problem."""
26    data = {}
27    data['distance_matrix'] = [
28        [
29            0, 548, 776, 696, 582, 274, 502, 194, 308, 194, 536, 502, 388, 354,
30            468, 776, 662
31        ],
32        [
33            548, 0, 684, 308, 194, 502, 730, 354, 696, 742, 1084, 594, 480, 674,
34            1016, 868, 1210
35        ],
36        [
37            776, 684, 0, 992, 878, 502, 274, 810, 468, 742, 400, 1278, 1164,
38            1130, 788, 1552, 754
39        ],
40        [
41            696, 308, 992, 0, 114, 650, 878, 502, 844, 890, 1232, 514, 628, 822,
42            1164, 560, 1358
43        ],
44        [
45            582, 194, 878, 114, 0, 536, 764, 388, 730, 776, 1118, 400, 514, 708,
46            1050, 674, 1244
47        ],
48        [
49            274, 502, 502, 650, 536, 0, 228, 308, 194, 240, 582, 776, 662, 628,
50            514, 1050, 708
51        ],
52        [
53            502, 730, 274, 878, 764, 228, 0, 536, 194, 468, 354, 1004, 890, 856,
54            514, 1278, 480
55        ],
56        [
57            194, 354, 810, 502, 388, 308, 536, 0, 342, 388, 730, 468, 354, 320,
58            662, 742, 856
59        ],
60        [
61            308, 696, 468, 844, 730, 194, 194, 342, 0, 274, 388, 810, 696, 662,
62            320, 1084, 514
63        ],
64        [
65            194, 742, 742, 890, 776, 240, 468, 388, 274, 0, 342, 536, 422, 388,
66            274, 810, 468
67        ],
68        [
69            536, 1084, 400, 1232, 1118, 582, 354, 730, 388, 342, 0, 878, 764,
70            730, 388, 1152, 354
71        ],
72        [
73            502, 594, 1278, 514, 400, 776, 1004, 468, 810, 536, 878, 0, 114,
74            308, 650, 274, 844
75        ],
76        [
77            388, 480, 1164, 628, 514, 662, 890, 354, 696, 422, 764, 114, 0, 194,
78            536, 388, 730
79        ],
80        [
81            354, 674, 1130, 822, 708, 628, 856, 320, 662, 388, 730, 308, 194, 0,
82            342, 422, 536
83        ],
84        [
85            468, 1016, 788, 1164, 1050, 514, 514, 662, 320, 274, 388, 650, 536,
86            342, 0, 764, 194
87        ],
88        [
89            776, 868, 1552, 560, 674, 1050, 1278, 742, 1084, 810, 1152, 274,
90            388, 422, 764, 0, 798
91        ],
92        [
93            662, 1210, 754, 1358, 1244, 708, 480, 856, 514, 468, 354, 844, 730,
94            536, 194, 798, 0
95        ],
96    ]
97    # [START demands_capacities]
98    data['demands'] = [0, 1, 1, 2, 4, 2, 4, 8, 8, 1, 2, 1, 2, 4, 4, 8, 8]
99    data['vehicle_capacities'] = [15, 15, 15, 15]
100    # [END demands_capacities]
101    data['num_vehicles'] = 4
102    data['depot'] = 0
103    return data
104    # [END data_model]
105
106
107# [START solution_printer]
108def print_solution(data, manager, routing, solution):
109    """Prints solution on console."""
110    print(f'Objective: {solution.ObjectiveValue()}')
111    total_distance = 0
112    total_load = 0
113    for vehicle_id in range(data['num_vehicles']):
114        index = routing.Start(vehicle_id)
115        plan_output = 'Route for vehicle {}:\n'.format(vehicle_id)
116        route_distance = 0
117        route_load = 0
118        while not routing.IsEnd(index):
119            node_index = manager.IndexToNode(index)
120            route_load += data['demands'][node_index]
121            plan_output += ' {0} Load({1}) -> '.format(node_index, route_load)
122            previous_index = index
123            index = solution.Value(routing.NextVar(index))
124            route_distance += routing.GetArcCostForVehicle(
125                previous_index, index, vehicle_id)
126        plan_output += ' {0} Load({1})\n'.format(manager.IndexToNode(index),
127                                                 route_load)
128        plan_output += 'Distance of the route: {}m\n'.format(route_distance)
129        plan_output += 'Load of the route: {}\n'.format(route_load)
130        print(plan_output)
131        total_distance += route_distance
132        total_load += route_load
133    print('Total distance of all routes: {}m'.format(total_distance))
134    print('Total load of all routes: {}'.format(total_load))
135    # [END solution_printer]
136
137
138def main():
139    """Solve the CVRP problem."""
140    # Instantiate the data problem.
141    # [START data]
142    data = create_data_model()
143    # [END data]
144
145    # Create the routing index manager.
146    # [START index_manager]
147    manager = pywrapcp.RoutingIndexManager(len(data['distance_matrix']),
148                                           data['num_vehicles'], data['depot'])
149    # [END index_manager]
150
151    # Create Routing Model.
152    # [START routing_model]
153    routing = pywrapcp.RoutingModel(manager)
154
155    # [END routing_model]
156
157    # Create and register a transit callback.
158    # [START transit_callback]
159    def distance_callback(from_index, to_index):
160        """Returns the distance between the two nodes."""
161        # Convert from routing variable Index to distance matrix NodeIndex.
162        from_node = manager.IndexToNode(from_index)
163        to_node = manager.IndexToNode(to_index)
164        return data['distance_matrix'][from_node][to_node]
165
166    transit_callback_index = routing.RegisterTransitCallback(distance_callback)
167    # [END transit_callback]
168
169    # Define cost of each arc.
170    # [START arc_cost]
171    routing.SetArcCostEvaluatorOfAllVehicles(transit_callback_index)
172
173    # [END arc_cost]
174
175    # Add Capacity constraint.
176    # [START capacity_constraint]
177    def demand_callback(from_index):
178        """Returns the demand of the node."""
179        # Convert from routing variable Index to demands NodeIndex.
180        from_node = manager.IndexToNode(from_index)
181        return data['demands'][from_node]
182
183    demand_callback_index = routing.RegisterUnaryTransitCallback(
184        demand_callback)
185    routing.AddDimensionWithVehicleCapacity(
186        demand_callback_index,
187        0,  # null capacity slack
188        data['vehicle_capacities'],  # vehicle maximum capacities
189        True,  # start cumul to zero
190        'Capacity')
191    # [END capacity_constraint]
192
193    # Setting first solution heuristic.
194    # [START parameters]
195    search_parameters = pywrapcp.DefaultRoutingSearchParameters()
196    search_parameters.first_solution_strategy = (
197        routing_enums_pb2.FirstSolutionStrategy.PATH_CHEAPEST_ARC)
198    search_parameters.local_search_metaheuristic = (
199        routing_enums_pb2.LocalSearchMetaheuristic.GUIDED_LOCAL_SEARCH)
200    search_parameters.time_limit.FromSeconds(1)
201    # [END parameters]
202
203    # Solve the problem.
204    # [START solve]
205    solution = routing.SolveWithParameters(search_parameters)
206    # [END solve]
207
208    # Print solution on console.
209    # [START print_solution]
210    if solution:
211        print_solution(data, manager, routing, solution)
212    # [END print_solution]
213
214
215if __name__ == '__main__':
216    main()
217# [END program]
218