def read_weather_data(r):

'''Read weather data from reader r in fixed-width format.

The fields are:

1 8 YYYYMMDD (date)

9 14 DDMMSS (latitude)

15 20 DDMMSS (longitude)

21 26 FF.FFF (temp, deg. C)

27 32 FF.FFF (humidity, %)

33 38 FF.FFF (pressure, kPa)

The result is a list of tuples of tuples,

where each tuple of tuples is of the form:

((Yr, Mo, Day), (Deg, Min, Sec), (Deg, Min, Sec), (Temp, Hum, Press))

'''

result = []

for line in r:

year = int(line[0:4])

month = int(line[4:6])

day = int(line[6:8])

lat_deg = int(line[8:10])

lat_min = int(line[10:12])

lat_sec = int(line[12:14])

long_deg = int(line[14:16])

long_min = int(line[16:18])

long_sec = int(line[18:20])

temp = float(line[20:26])

hum = float(line[26:32])

press = float(line[32:38])

result.append(((year, month, day),

(lat_deg, lat_min, lat_sec),

(long_deg, long_min, long_sec),

(temp, hum, press)))

return result