weatherdata_utils.py

import urllib.request as http
import xml.etree.ElementTree as ET
import datetime as dt
from email.utils import parsedate_to_datetime

class WeatherStation:
    '''Handles connection to weather station feed
    and extraction of temperature,pressure and humidity from raw response'''
    def __init__(self,url):
        self.__id__          = None
        self.__timeupdated__ = dt.datetime(1960,1,1,tzinfo=dt.timezone.utc)#initialized to a date in the past
        self.__temp__        = None
        self.__pressure__    = None
        self.__humidity__    = None
        self.__windspeed__   = None
        self.__url__         = url
        self.raw=""
    
    def update(self):
        #get raw data from url
        try:
            rawtxt = http.urlopen(self.__url__).read()
        except:
            print('Couldn\'t Open URL.')
            return False
                
        self.raw = rawtxt
        
        #parse xml to get data 
        try:
            (ID,
             temp,
             pressure,
             humidity,
             timeupdated,
             windspeed)= newData = self.__parse__(rawtxt)
        except:
            print('Parsing Error, Data was either missing or in an unexpected format.')
            return False
        
        #update if the data is new
        if timeupdated > self.__timeupdated__:
            (self.__id__,
             self.__temp__,
             self.__pressure__,
             self.__humidity__,
             self.__timeupdated__,
             self.__windspeed__) = newData
            
            return True
        else:
            return False
    
    def __parse__(self,raw):
        tree = ET.fromstring(raw)
        
        str_id                = [i for i in tree.find('station_id').itertext()     ][0]
        str_temp_f            = [i for i in tree.find('temp_f').itertext()         ][0]
        str_pressure_mb       = [i for i in tree.find('pressure_mb').itertext()    ][0]
        str_relative_humidity = [i for i in tree.find('relative_humidity').itertext()][0]
        str_time              = [i for i in tree.find('observation_time_rfc822').itertext()][0]
        str_wind_speed        = [i for i in tree.find('wind_mph').itertext()         ][0]
        
        return (str_id,
                float(str_temp_f           ),
                float(str_pressure_mb      ),
                float(str_relative_humidity),
                parsedate_to_datetime(str_time),
                float(str_wind_speed))
    
    def ID(self):
        return self.__id__
    
    def temp(self):
        return self.__temp__
    
    def pressure(self):
        return self.__pressure__
    
    def humidity(self):
        return self.__humidity__
    def time(self):
        return self.__timeupdated__
    def wind_speed(self):
        return self.__windspeed__