我正在嘗試解決一個有5個司機送貨的車輛路線問題。我用haversine和lat long來計算距離矩陣。我是新的或工具，所以遵循vrp的例子。在

問題是，對于5個驅動程序，只為2個驅動程序生成路由，并且這些路徑非常長。我想生成多條較短的路線，這樣所有的驅動程序都被利用了。請檢查我是否設置了錯誤的約束。在

有人能解釋一下，如何在谷歌或工具中設置“距離”維度和設置全局泛成本系數。這是代碼和輸出。在from __future__ import print_function

import pandas as pd

import numpy as np

import googlemaps

import math

from ortools.constraint_solver import routing_enums_pb2

from ortools.constraint_solver import pywrapcp

gmaps = googlemaps.Client(key='API Key')

def calculate_geocodes():

df = pd.read_csv("banglore_zone.csv")

df['lat'] = pd.Series(np.repeat(0, df.size), dtype=float)

df['long'] = pd.Series(np.repeat(0, df.size), dtype=float)

result = np.zeros([df.size, 2])

for index, row in df.iterrows():

# print(row['Address'])

geocode_result = gmaps.geocode(row['Address'])[0]

lat = (geocode_result['geometry']['location']['lat'])

lng = (geocode_result['geometry']['location']['lng'])

result[index] = lat, lng

df.lat[index] = lat

df.long[index] = lng

print("First step", df)

coords = df.as_matrix(columns=['lat', 'long'])

return coords, df

def calculate_distance_matrix(coordinates, gmaps):

distance_matrix = np.zeros(

(np.size(coordinates, 0), np.size(coordinates, 0))) # create an empty matrix for distance between all locations

for index in range(0, np.size(coordinates, 0)):

src = coordinates[index]

for ind in range(0, np.size(coordinates, 0)):

dst = coordinates[ind]

distance_matrix[index, ind] = distance(src[0], src[1], dst[0], dst[1])

return distance_matrix

def distance(lat1, long1, lat2, long2):

# Note: The formula used in this function is not exact, as it assumes

# the Earth is a perfect sphere.

# Mean radius of Earth in miles

radius_earth = 3959

# Convert latitude and longitude to

# spherical coordinates in radians.

degrees_to_radians = math.pi / 180.0

phi1 = lat1 * degrees_to_radians

phi2 = lat2 * degrees_to_radians

lambda1 = long1 * degrees_to_radians

lambda2 = long2 * degrees_to_radians

dphi = phi2 - phi1

dlambda = lambda2 - lambda1

a = haversine(dphi) + math.cos(phi1) * math.cos(phi2) * haversine(dlambda)

c = 2 * math.atan2(math.sqrt(a), math.sqrt(1 - a))

d = radius_earth * c

return d

def haversine(angle):

h = math.sin(angle / 2) ** 2

return h

def create_data_model(distance_matrix, number_of_vehicles, depot):

"""Stores the data for the problem."""

data = {}

data['distance_matrix'] = distance_matrix

print(distance_matrix)

data['num_vehicles'] = number_of_vehicles

data['depot'] = depot

return data

def print_solution(data, manager, routing, solution, address_dataframe):

"""Prints solution on console."""

max_route_distance = 0

for vehicle_id in range(data['num_vehicles']):

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(address_dataframe.iloc[manager.IndexToNode(index), 0])

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():

coordinates, address_dataframe = calculate_geocodes()

distance_matrix = calculate_distance_matrix(coordinates, gmaps)

data = create_data_model(distance_matrix, 5, 0)

# Create the routing index manager.

manager = pywrapcp.RoutingIndexManager(

len(data['distance_matrix']), data['num_vehicles'], data['depot'])

# Create Routing Model.

routing = pywrapcp.RoutingModel(manager)

# 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

80, # vehicle maximum travel distance

True, # start cumul to zero

dimension_name)

distance_dimension = routing.GetDimensionOrDie(dimension_name)

distance_dimension.SetGlobalSpanCostCoefficient(100)

# Setting first solution heuristic.

search_parameters = pywrapcp.DefaultRoutingSearchParameters()

search_parameters.local_search_metaheuristic = (

routing_enums_pb2.LocalSearchMetaheuristic.GUIDED_LOCAL_SEARCH)

search_parameters.time_limit.seconds = 120

search_parameters.log_search = False

# Solve the problem.

solution = routing.SolveWithParameters(search_parameters)

# Print solution on console.

if solution:

print_solution(data, manager, routing, solution, address_dataframe)

if __name__ == '__main__':

main()

距離矩陣和輸出是-

^{pr2}$

總結

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