不同车速的车辆路线（谷歌或工具）答案

【问题标题】：Vehicle Routing with Different Vehicle Speed (Google OR Tools)不同车速的车辆路线（谷歌或工具）
【发布时间】：2020-07-29 20:13:38
【问题描述】：

目前，我正在研究不同车速的车辆路线问题。我的方法是使用每辆车的速度调整比（这意味着我有默认速度），以建立我使用代码的时间约束：（data['travel_service'] 是时间矩阵 + 服务时间，data['travel_service'] 只是服务时间）

data['vehicle_speed_adjustment'] = [1.5, 1.3, 1.2, 1]
def create_vehicle_travel_service_time_callback(travel_service_matrix, service_time, speed_adjust_ratio):
    def time_callback(from_index, to_index):
        """Returns the travel time between the two nodes + the service time of starting node."""
        # Convert from routing variable Index to time matrix NodeIndex.
        from_node = manager.IndexToNode(from_index)
        to_node = manager.IndexToNode(to_index)
        if travel_service_matrix[from_node][to_node] == sys.maxsize or travel_service_matrix[from_node][to_node] == service_time[from_node]:
            return travel_service_matrix[from_node][to_node]
        else:
            return int((travel_service_matrix[from_node][to_node]-service_time[from_node])/speed_adjust_ratio) + service_time[from_node]
    return time_callback

# time_callback_index = []
for vehicle_id in range(data['num_vehicles']):
    time_callback = create_vehicle_travel_service_time_callback(data['travel_service'], data['service_time'], data['vehicle_speed_adjustment'][vehicle_id])
    time_callback_index = routing.RegisterTransitCallback(time_callback)
    print(time_callback_index)
    routing.AddDimension(
        time_callback_index,
        max_waiting_time,  # allow waiting time
        max_operation_time,  # maximum time per vehicle
        False,  
        'Time')
    
time_dimension = routing.GetDimensionOrDie('Time')

问题是，当我尝试运行程序时，程序只识别data['vehicle_speed_adjustment'] 列表的第一个值，即 1.5，并将其应用于每辆车。

有人可以解释为什么会这样吗？

data['travel_service'] = [[0, 4, 22, 21, 48, 28, 8, 23, 16, 14, 23, 37], [59, 0, 79, 78, 104, 84, 63, 76, 68, 66, 78, 91], [32, 34, 0, 12, 38, 32, 31, 14, 41, 40, 41, 52], [27, 29, 8, 0, 35, 28, 27, 11, 36, 35, 37, 47], [58, 59, 38, 39, 0, 39, 52, 41, 62, 61, 60, 60], [36, 37, 30, 30, 37, 0, 32, 30, 41, 40, 39, 34], [18, 18, 31, 31, 52, 34, 0, 32, 20, 19, 22, 39], [33, 31, 14, 15, 41, 32, 32, 0, 42, 41, 43, 54], [44, 41, 59, 58, 80, 61, 38, 60, 0, 31, 36, 53], [69, 66, 85, 84, 106, 87, 64, 86, 58, 0, 65, 83], [33, 33, 41, 41, 60, 41, 22, 43, 18, 20, 0, 31], [45, 44, 50, 49, 58, 34, 37, 52, 33, 36, 29, 0]]

data['travel_service'] = [0, 55, 10, 6, 10, 8, 10, 10, 28, 55, 10, 8]

data['num_vehicles'] = 4

【问题讨论】：

粘贴代码时出现问题且缩进不正确（例如函数 defs 从同一级别开始）。你能修复它以便我们更好地理解你的代码吗？
有没有机会你也可以提供几行数据数据框？
已经添加了一些数据
什么是数据类型？是字典吗？您是否尝试在将data['vehicle_speed_adjustment'][vehicle_id] 传递给create_vehicle_travel_service_time_callback 之前打印它以检查此值是否正确？
是的，数据是字典。我已经检查过了，值是正确的。但是，当我尝试在time_callback 之后打印时，它开始只识别data['vehicle_speed_adjustment'] 的第一个值。

标签： python or-tools

【解决方案1】：

差不多好了，您只需要创建一个回调索引数组，然后将该数组传递给 AddDimension...
注意：数组长度必须等于车辆编号。注意2：您可以为少数车辆重复使用相同的注册回调索引例如你有两辆自行车和三辆汽车，你可以传递一个数组[1, 1, 2, 2, 2]，假设RegisterTransitCallback返回1和2...

参考：https://github.com/google/or-tools/blob/45770b833997f827d322e929b1ed4781c4e60d44/ortools/constraint_solver/routing.h#L416-L418

time_callback_indices = []
for vehicle_id in range(data['num_vehicles']):
    time_callback = create_vehicle_travel_service_time_callback(data['travel_service'], data['service_time'], data['vehicle_speed_adjustment'][vehicle_id])
    time_callback_indices.append(routing.RegisterTransitCallback(time_callback))
    #print(time_callback_index)

routing.AddDimensionWithVehicleTransits(
    time_callback_indices,
    max_waiting_time,  # allow waiting time
    max_operation_time,  # maximum time per vehicle
    False,  
    'Time')

【讨论】：