In python how do I convert a datetime in a specific local time (not my local) to UTC

Question

I'm pulling data from a London based service and they are giving me date&time info in London local time.So UTC in winter and BST(UTC+1) in summer.

Internally we use UTC for everything, in Python how do I convert the London stuff to UTC in a way that will account for daylight savings?

I appreciate that some times around the DST rollover are ambiguous, that's acceptable as long as it works the rest of the year.

For completeness, I'm getting the following info from them:

dt="2012-10-12T19:30:00"
lcnid="LDN"
locale="en-gb"

Answer 1

You need to use a timezone object; these don't come with Python itself as the data changes too often. The pytz library is easily installed though.

Example conversion:

>>> import pytz
>>> import datetime
>>> bst = pytz.timezone('Europe/London')
>>> dt = datetime.datetime.strptime('2012-10-12T19:30:00', '%Y-%m-%dT%H:%M:%S')
>>> dt
datetime.datetime(2012, 10, 12, 19, 30)
>>> bst.localize(dt)
datetime.datetime(2012, 10, 12, 19, 30, tzinfo=<DstTzInfo 'Europe/London' BST+1:00:00 DST>)
>>> bst.localize(dt).astimezone(pytz.utc)
datetime.datetime(2012, 10, 12, 18, 30, tzinfo=<UTC>)