Mizux/chain.py

## chain.py
#!/usr/bin/env python3
"""
Test Multiple route chains constraint

We have several chain [A, B, C], [U, V, W], [X,Y] etc..
and a bunch of regular nodes [1,2,3,...]
constraints:
* Can't interleave chains e.g. "A -> B -> X -> C -> Y" is forbidden
* Can have regular node inside a chain e.g. "A -> 3 -> B -> 1 -> C" is OK
"""

from ortools.constraint_solver import routing_enums_pb2
from ortools.constraint_solver import pywrapcp


def print_solution(manager, routing, solution):
    """Prints solution on console."""
    print(f'Objective: {solution.ObjectiveValue()}')
    max_route_distance = 0
    for vehicle_id in range(manager.GetNumberOfVehicles()):
        index = routing.Start(vehicle_id)
        plan_output = 'Route for vehicle {}:\n'.format(vehicle_id)
        route_distance = 0
        while not routing.IsEnd(index):
            plan_output += ' {} -> '.format(manager.IndexToNode(index))
            previous_index = index
            index = solution.Value(routing.NextVar(index))
            route_distance += routing.GetArcCostForVehicle(
                previous_index, index, vehicle_id)
        plan_output += '{}\n'.format(manager.IndexToNode(index))
        plan_output += 'Distance of the route: {}m\n'.format(route_distance)
        print(plan_output)
        max_route_distance = max(route_distance, max_route_distance)
    print('Maximum of the route distances: {}m'.format(max_route_distance))


def main():
    data = {}
    data['distance_matrix'] = [
        [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
        [
            0, 0, 684, 308, 194, 502, 730, 354, 696, 742, 1084, 594, 480, 674,
            1016, 868, 1210
        ],
        [
            0, 684, 0, 992, 878, 502, 274, 810, 468, 742, 400, 1278, 1164,
            1130, 788, 1552, 754
        ],
        [
            0, 308, 992, 0, 114, 650, 878, 502, 844, 890, 1232, 514, 628, 822,
            1164, 560, 1358
        ],
        [
            0, 194, 878, 114, 0, 536, 764, 388, 730, 776, 1118, 400, 514, 708,
            1050, 674, 1244
        ],
        [
            0, 502, 502, 650, 536, 0, 228, 308, 194, 240, 582, 776, 662, 628,
            514, 1050, 708
        ],
        [
            0, 730, 274, 878, 764, 228, 0, 536, 194, 468, 354, 1004, 890, 856,
            514, 1278, 480
        ],
        [
            0, 354, 810, 502, 388, 308, 536, 0, 342, 388, 730, 468, 354, 320,
            662, 742, 856
        ],
        [
            0, 696, 468, 844, 730, 194, 194, 342, 0, 274, 388, 810, 696, 662,
            320, 1084, 514
        ],
        [
            0, 742, 742, 890, 776, 240, 468, 388, 274, 0, 342, 536, 422, 388,
            274, 810, 468
        ],
        [
            0, 1084, 400, 1232, 1118, 582, 354, 730, 388, 342, 0, 878, 764,
            730, 388, 1152, 354
        ],
        [
            0, 594, 1278, 514, 400, 776, 1004, 468, 810, 536, 878, 0, 114, 308,
            650, 274, 844
        ],
        [
            0, 480, 1164, 628, 514, 662, 890, 354, 696, 422, 764, 114, 0, 194,
            536, 388, 730
        ],
        [
            0, 674, 1130, 822, 708, 628, 856, 320, 662, 388, 730, 308, 194, 0,
            342, 422, 536
        ],
        [
            0, 1016, 788, 1164, 1050, 514, 514, 662, 320, 274, 388, 650, 536,
            342, 0, 764, 194
        ],
        [
            0, 868, 1552, 560, 674, 1050, 1278, 742, 1084, 810, 1152, 274, 388,
            422, 764, 0, 798
        ],
        [
            0, 1210, 754, 1358, 1244, 708, 480, 856, 514, 468, 354, 844, 730,
            536, 194, 798, 0
        ],
    ]
    data['num_vehicles'] = 1
    data['starts'] = [1]
    data['ends'] = [0]

    data['events'] = [2, 3, 4, 5]
    data['routes'] = [[6, 7], [8, 9, 10], [11, 12, 13, 14, 15, 16]]

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

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

    # Dimensions
    # 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 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 Distance constraint.
    dimension_name = 'Distance'
    routing.AddDimension(
        transit_callback_index,
        0,  # no slack
        99999999999,  # vehicle maximum travel distance
        True,  # start cumul to zero
        dimension_name)
    #distance_dimension = routing.GetDimensionOrDie(dimension_name)
    #distance_dimension.SetGlobalSpanCostCoefficient(0)

    # Count dimensions
    routing.AddConstantDimension(1, 1000000, True, "Count")
    count_dimension = routing.GetDimensionOrDie("Count")

    # Sequence constraint
    for route in data['routes']:
        for i in range(len(route) - 1):
            current_index = manager.NodeToIndex(route[i])
            next_index = manager.NodeToIndex(route[i+1])
            solver.Add(
                count_dimension.CumulVar(current_index) <
                count_dimension.CumulVar(next_index))

    # Enforce same vehicle on route sequence
    # note(mizux): this is not needed for a single vehicle problem...
    for route in data['routes']:
        for i in range(len(route) - 1):
            current_index = manager.NodeToIndex(route[i])
            next_index = manager.NodeToIndex(route[i + 1])
            # same vehicle condition
            solver.Add(
                routing.VehicleVar(current_index) == routing.VehicleVar(next_index))

    # Forbid interleaved routes
    # i.e. we have for any pair of chain X, Y "end_X < start_Y OR end_Y < start_X"
    for i in range(len(data['routes'])):
        for j in range(i+1, len(data['routes'])):
          #print(f'indices {i},{j}')
          start_i = manager.NodeToIndex(data['routes'][i][0])
          end_i = manager.NodeToIndex(data['routes'][i][-1])
          start_j = manager.NodeToIndex(data['routes'][j][0])
          end_j = manager.NodeToIndex(data['routes'][j][-1])
          #print(f'{end_i} < {start_j}')
          #print(f'{end_j} < {start_i}')
          first = count_dimension.CumulVar(end_i) < count_dimension.CumulVar(start_j)
          second = count_dimension.CumulVar(end_j) < count_dimension.CumulVar(start_i)
          solver.Add(solver.Sum([first, second]) == 1)

    # Setting first solution heuristic.
    # [START parameters]
    search_parameters = pywrapcp.DefaultRoutingSearchParameters()
    search_parameters.first_solution_strategy = (
        routing_enums_pb2.FirstSolutionStrategy.PATH_CHEAPEST_ARC)
    search_parameters.local_search_metaheuristic = (
        routing_enums_pb2.LocalSearchMetaheuristic.GUIDED_LOCAL_SEARCH)
    search_parameters.log_search = True
    search_parameters.time_limit.FromSeconds(5)
    # [END parameters]

    # Solve problem
    solution = routing.SolveWithParameters(search_parameters)
    if solution:
        print_solution(manager, routing, solution)
    else:
        print("NO SOLUTION FOUND!")


if __name__ == '__main__':
    main()

## zz.md

      
    Raw
  

              zz.md
            
          
    Possible output
./chain.py
...
 memory used = 14.71 MB, limit = 99%)
I0727 15:23:45.283691  9085 search.cc:260] Solution #1119 (5374, objective maximum = 7986, time = 4995 ms, branches = 25463, failures = 140128, depth = 33, TwoOpt, neighbors = 344217, filtered neighbors = 128207, accepted neighbors = 1119, memory used = 14.71 MB, limit = 99%)
I0727 15:23:50.335205  9085 search.cc:260] Finished search tree (time = 5000 ms, branches = 25466, failures = 140305, neighbors = 344421, filtered neighbors = 128353, accepted neigbors = 1119, memory used = 14.71 MB)
I0727 15:23:50.362792  9085 search.cc:260] End search (time = 5000 ms, branches = 25466, failures = 140305, memory used = 14.71 MB, speed = 5093 branches/s)
Objective: 5374
Route for vehicle 0:
 1 ->  4 ->  3 ->  11 ->  12 ->  13 ->  14 ->  15 ->  16 ->  8 ->  9 ->  10 ->  2 ->  6 ->  5 ->  7 -> 0
Distance of the route: 5374m

Maximum of the route distances: 5374m
	#!/usr/bin/env python3
	"""
	Test Multiple route chains constraint

	We have several chain [A, B, C], [U, V, W], [X,Y] etc..
	and a bunch of regular nodes [1,2,3,...]
	constraints:
	* Can't interleave chains e.g. "A -> B -> X -> C -> Y" is forbidden
	* Can have regular node inside a chain e.g. "A -> 3 -> B -> 1 -> C" is OK
	"""

	from ortools.constraint_solver import routing_enums_pb2
	from ortools.constraint_solver import pywrapcp


	def print_solution(manager, routing, solution):
	"""Prints solution on console."""
	print(f'Objective: {solution.ObjectiveValue()}')
	max_route_distance = 0
	for vehicle_id in range(manager.GetNumberOfVehicles()):
	index = routing.Start(vehicle_id)
	plan_output = 'Route for vehicle {}:\n'.format(vehicle_id)
	route_distance = 0
	while not routing.IsEnd(index):
	plan_output += ' {} -> '.format(manager.IndexToNode(index))
	previous_index = index
	index = solution.Value(routing.NextVar(index))
	route_distance += routing.GetArcCostForVehicle(
	previous_index, index, vehicle_id)
	plan_output += '{}\n'.format(manager.IndexToNode(index))
	plan_output += 'Distance of the route: {}m\n'.format(route_distance)
	print(plan_output)
	max_route_distance = max(route_distance, max_route_distance)
	print('Maximum of the route distances: {}m'.format(max_route_distance))


	def main():
	data = {}
	data['distance_matrix'] = [
	[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
	[
	0, 0, 684, 308, 194, 502, 730, 354, 696, 742, 1084, 594, 480, 674,
	1016, 868, 1210
	],
	[
	0, 684, 0, 992, 878, 502, 274, 810, 468, 742, 400, 1278, 1164,
	1130, 788, 1552, 754
	],
	[
	0, 308, 992, 0, 114, 650, 878, 502, 844, 890, 1232, 514, 628, 822,
	1164, 560, 1358
	],
	[
	0, 194, 878, 114, 0, 536, 764, 388, 730, 776, 1118, 400, 514, 708,
	1050, 674, 1244
	],
	[
	0, 502, 502, 650, 536, 0, 228, 308, 194, 240, 582, 776, 662, 628,
	514, 1050, 708
	],
	[
	0, 730, 274, 878, 764, 228, 0, 536, 194, 468, 354, 1004, 890, 856,
	514, 1278, 480
	],
	[
	0, 354, 810, 502, 388, 308, 536, 0, 342, 388, 730, 468, 354, 320,
	662, 742, 856
	],
	[
	0, 696, 468, 844, 730, 194, 194, 342, 0, 274, 388, 810, 696, 662,
	320, 1084, 514
	],
	[
	0, 742, 742, 890, 776, 240, 468, 388, 274, 0, 342, 536, 422, 388,
	274, 810, 468
	],
	[
	0, 1084, 400, 1232, 1118, 582, 354, 730, 388, 342, 0, 878, 764,
	730, 388, 1152, 354
	],
	[
	0, 594, 1278, 514, 400, 776, 1004, 468, 810, 536, 878, 0, 114, 308,
	650, 274, 844
	],
	[
	0, 480, 1164, 628, 514, 662, 890, 354, 696, 422, 764, 114, 0, 194,
	536, 388, 730
	],
	[
	0, 674, 1130, 822, 708, 628, 856, 320, 662, 388, 730, 308, 194, 0,
	342, 422, 536
	],
	[
	0, 1016, 788, 1164, 1050, 514, 514, 662, 320, 274, 388, 650, 536,
	342, 0, 764, 194
	],
	[
	0, 868, 1552, 560, 674, 1050, 1278, 742, 1084, 810, 1152, 274, 388,
	422, 764, 0, 798
	],
	[
	0, 1210, 754, 1358, 1244, 708, 480, 856, 514, 468, 354, 844, 730,
	536, 194, 798, 0
	],
	]
	data['num_vehicles'] = 1
	data['starts'] = [1]
	data['ends'] = [0]

	data['events'] = [2, 3, 4, 5]
	data['routes'] = [[6, 7], [8, 9, 10], [11, 12, 13, 14, 15, 16]]

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

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

	# Dimensions
	# 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 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 Distance constraint.
	dimension_name = 'Distance'
	routing.AddDimension(
	transit_callback_index,
	0, # no slack
	99999999999, # vehicle maximum travel distance
	True, # start cumul to zero
	dimension_name)
	#distance_dimension = routing.GetDimensionOrDie(dimension_name)
	#distance_dimension.SetGlobalSpanCostCoefficient(0)

	# Count dimensions
	routing.AddConstantDimension(1, 1000000, True, "Count")
	count_dimension = routing.GetDimensionOrDie("Count")

	# Sequence constraint
	for route in data['routes']:
	for i in range(len(route) - 1):
	current_index = manager.NodeToIndex(route[i])
	next_index = manager.NodeToIndex(route[i+1])
	solver.Add(
	count_dimension.CumulVar(current_index) <
	count_dimension.CumulVar(next_index))

	# Enforce same vehicle on route sequence
	# note(mizux): this is not needed for a single vehicle problem...
	for route in data['routes']:
	for i in range(len(route) - 1):
	current_index = manager.NodeToIndex(route[i])
	next_index = manager.NodeToIndex(route[i + 1])
	# same vehicle condition
	solver.Add(
	routing.VehicleVar(current_index) == routing.VehicleVar(next_index))

	# Forbid interleaved routes
	# i.e. we have for any pair of chain X, Y "end_X < start_Y OR end_Y < start_X"
	for i in range(len(data['routes'])):
	for j in range(i+1, len(data['routes'])):
	#print(f'indices {i},{j}')
	start_i = manager.NodeToIndex(data['routes'][i][0])
	end_i = manager.NodeToIndex(data['routes'][i][-1])
	start_j = manager.NodeToIndex(data['routes'][j][0])
	end_j = manager.NodeToIndex(data['routes'][j][-1])
	#print(f'{end_i} < {start_j}')
	#print(f'{end_j} < {start_i}')
	first = count_dimension.CumulVar(end_i) < count_dimension.CumulVar(start_j)
	second = count_dimension.CumulVar(end_j) < count_dimension.CumulVar(start_i)
	solver.Add(solver.Sum([first, second]) == 1)

	# Setting first solution heuristic.
	# [START parameters]
	search_parameters = pywrapcp.DefaultRoutingSearchParameters()
	search_parameters.first_solution_strategy = (
	routing_enums_pb2.FirstSolutionStrategy.PATH_CHEAPEST_ARC)
	search_parameters.local_search_metaheuristic = (
	routing_enums_pb2.LocalSearchMetaheuristic.GUIDED_LOCAL_SEARCH)
	search_parameters.log_search = True
	search_parameters.time_limit.FromSeconds(5)
	# [END parameters]

	# Solve problem
	solution = routing.SolveWithParameters(search_parameters)
	if solution:
	print_solution(manager, routing, solution)
	else:
	print("NO SOLUTION FOUND!")


	if __name__ == '__main__':
	main()