Clean up weather type results (night/day) about datapoint-python

[jacobtomlinson]

Example from log file for site Clifton Hill Ski Slope Exeter. It continues to be night until 9am.

Tue Dec  2 09:00:03 2014 - Cloudy
Tue Dec  2 10:00:03 2014 - Cloudy
Tue Dec  2 11:00:08 2014 - Cloudy
Tue Dec  2 12:00:04 2014 - Cloudy
Tue Dec  2 13:00:09 2014 - Partly cloudy (day)
Tue Dec  2 14:00:02 2014 - Partly cloudy (day)
Tue Dec  2 15:00:02 2014 - Partly cloudy (day)
Tue Dec  2 16:00:04 2014 - Partly cloudy (day)
Tue Dec  2 17:00:04 2014 - Partly cloudy (day)
Tue Dec  2 18:00:04 2014 - Partly cloudy (day)
Tue Dec  2 19:00:02 2014 - Partly cloudy (night)
Tue Dec  2 20:00:02 2014 - Partly cloudy (night)
Tue Dec  2 21:00:03 2014 - Partly cloudy (night)
Tue Dec  2 22:00:02 2014 - Partly cloudy (night)
Tue Dec  2 23:00:01 2014 - Partly cloudy (night)
Unexpected error: <type 'exceptions.NameError'> on line 64
Wed Dec  3 01:00:01 2014 - Clear night
Wed Dec  3 02:00:03 2014 - Clear night
Wed Dec  3 03:00:04 2014 - Clear night
Wed Dec  3 04:00:02 2014 - Partly cloudy (night)
Wed Dec  3 05:00:02 2014 - Partly cloudy (night)
Wed Dec  3 06:00:04 2014 - Partly cloudy (night)
Wed Dec  3 07:00:01 2014 - Clear night
Wed Dec  3 08:00:02 2014 - Clear night
Wed Dec  3 09:00:04 2014 - Clear night
Wed Dec  3 10:00:05 2014 - Sunny day

Ignote the error at midnight, this is covered by #19.

[jacobtomlinson]

After analysing the log file further it appears that night starts from the 19:00 timestep and finishes at the 09:00 timestep inclusive. This is consistent across a 2 month logging period (October-November).

It is possible that these are hard values set in the backend and no sunrise/sunset calculations are used.

In the last 2 months there have been no occurances of a day timestep reported at night although anecdotally I can say I've seen it happen in the past.

[EJEP]

I think stripping the day/night, calculating and storing separately is better. It seems strange that some types of weather (partly cloudy) have day/night given but others (cloudy) do not. Given the date and time is already stored for each timestep I'm not sure there's much point storing night/day at all.