Python 3.x 如何使用GTFS_RealTime_pb2.py库生成GTFS RealTime VehiclePosition.pb（二进制数据编码格式）文件？

如何将FeedMessage转换为Binarray格式？应使用哪个函数调用进行转换

I am using gtfs_realtime_pb2.py libarary to generate feed .How do i get encoded format of the vehiclePosition.pb ,after successfully creation of FeedMessage by using gtfs_realtime_pb2.py ?


I don't know the role of Descriptor here . How do i use this Descriptor to get data from library ?

 feedMesssage = gtfs_realtime_pb2.FeedMessage()
 feedMesssage.header.timestamp = 1566545545
 feedMesssage.header.incrementality = 1
 feedMesssage.header.gtfs_realtime_version = bytes(1)
    for serviceKey in serviceGpsDict:
        feedEntity = gtfs_realtime_pb2.FeedEntity()
        feedEntity.vehicle.trip.trip_id = 'testKey'
        feedEntity.vehicle.vehicle.id = 'DL 26HK 2758'
        feedEntity.vehicle.timestamp = 1566545545       
        feedEntity.vehicle.position.latitude = 28.7041 
        feedEntity.vehicle.position.longitude = 77.1025
        feedMesssage.entity.append(feedEntity)