hsl_hfp_data.py

# -*- coding: utf-8 -*-
"""
Created on Thu Feb 14 16:54:39 2019

@author: topit
MQTT part based on: http://www.steves-internet-guide.com/into-mqtt-python-client/
API docs for HSL high-frequency positioning: https://digitransit.fi/en/developers/apis/4-realtime-api/vehicle-positions/
"""

import paho.mqtt.client as mqtt
import json 
import csv


# The callback for when the client receives a CONNACK response from the server.
def on_connect(client, userdata, flags, rc):
    if rc==0:
        print("connected OK Returned code=",rc)
    else:
        print("Bad connection Returned code=",rc)

    # Subscribing in on_connect() means that if we lose the connection and
    # reconnect then subscriptions will be renewed.
    # This particular topic collects ALL traffic
    client.subscribe("/hfp/v1/journey/#")

# The callback for when a PUBLISH message is received from the server.
def on_message(client, userdata, msg):
    j = msg.payload.decode('utf8').replace("'", '"')
    d = json.loads(j)
    v = d["VP"]      
    
    # I don't want all of the data, so I define here the values I want
    values=v['long'],v['lat'],v['desi'],v['oper'],v['jrn'],v['line'],v['spd'], v['dl'], v['hdg'],v['drst'],v['veh'],v['tsi']
    
    # There are some nulls in there, so this is just a stupid way to exclude those
    if v['lat'] > 0:
        with open(r'hsl_mqtt.csv', 'a') as f:
            writer = csv.writer(f, quoting=csv.QUOTE_NONE, lineterminator='\n')
            writer.writerow(values)

client = mqtt.Client()
client.on_connect = on_connect
client.on_message = on_message

client.connect("mqtt.hsl.fi", 1883, 60)

# Blocking call that processes network traffic, dispatches callbacks and
# handles reconnecting.
# Other loop*() functions are available that give a threaded interface and a
# manual interface.
client.loop_forever()