def draw_route_graph(data: dict,
routing: pywrapcp.RoutingModel,
assignment: pywrapcp.Assignment,
filename: str = 'route.png',
prog='sfdp'):
"""
Draw a route graph based on the solution of the problem.
"""
weights = data['weights']
demands = data['demands']
time_windows = data['time_windows']
graph = pgv.AGraph(directed=True)
def _node(index: int) -> str:
if index == 0:
return f'{index}\nDepot'
return f'{index}\nDemand: {demands[index]}\nRange: {time_windows[index]}'
for vehicle_id in range(data['num_vehicles']):
index = routing.Start(vehicle_id)
while not routing.IsEnd(index):
node_index = routing.IndexToNode(index)
next_index = assignment.Value(routing.NextVar(index))
next_node_index = routing.IndexToNode(next_index)
weight = weights[node_index][next_node_index]
graph.add_edge(
_node(node_index),
_node(next_node_index),
weight=weight,
label=weight,
)
index = next_index
graph.draw(filename, prog=prog)
print(f'The route graph has been saved to {filename}.')
def node_properties(
routing: pywrapcp.RoutingModel,
assignment: pywrapcp.Assignment,
capacity_dimension: pywrapcp.RoutingDimension,
time_dimension: pywrapcp.RoutingDimension,
index: int,
) -> tuple:
"""
Get a node's properties on the index.
"""
node_index = routing.IndexToNode(index)
load = assignment.Value(capacity_dimension.CumulVar(index))
time_var = time_dimension.CumulVar(index)
time_min, time_max = assignment.Min(time_var), assignment.Max(time_var)
return (node_index, load, time_min, time_max)
