[python] Python strptime() and timezones?

I have a CSV dumpfile from a Blackberry IPD backup, created using IPDDump. The date/time strings in here look something like this (where EST is an Australian time-zone):

Tue Jun 22 07:46:22 EST 2010

I need to be able to parse this date in Python. At first, I tried to use the strptime() function from datettime.

>>> datetime.datetime.strptime('Tue Jun 22 12:10:20 2010 EST', '%a %b %d %H:%M:%S %Y %Z')

However, for some reason, the datetime object that comes back doesn't seem to have any tzinfo associated with it.

I did read on this page that apparently datetime.strptime silently discards tzinfo, however, I checked the documentation, and I can't find anything to that effect documented here.

I have been able to get the date parsed using a third-party Python library, dateutil, however I'm still curious as to how I was using the in-built strptime() incorrectly? Is there any way to get strptime() to play nicely with timezones?

I recommend using python-dateutil. Its parser has been able to parse every date format I've thrown at it so far.

>>> from dateutil import parser
>>> parser.parse("Tue Jun 22 07:46:22 EST 2010")
datetime.datetime(2010, 6, 22, 7, 46, 22, tzinfo=tzlocal())
>>> parser.parse("Fri, 11 Nov 2011 03:18:09 -0400")
datetime.datetime(2011, 11, 11, 3, 18, 9, tzinfo=tzoffset(None, -14400))
>>> parser.parse("Sun")
datetime.datetime(2011, 12, 18, 0, 0)
>>> parser.parse("10-11-08")
datetime.datetime(2008, 10, 11, 0, 0)

and so on. No dealing with strptime() format nonsense... just throw a date at it and it Does The Right Thing.

Update: Oops. I missed in your original question that you mentioned that you used dateutil, sorry about that. But I hope this answer is still useful to other people who stumble across this question when they have date parsing questions and see the utility of that module.

Since strptime returns a datetime object which has tzinfo attribute, We can simply replace it with desired timezone.

>>> import datetime

>>> date_time_str = '2018-06-29 08:15:27.243860'
>>> date_time_obj = datetime.datetime.strptime(date_time_str, '%Y-%m-%d %H:%M:%S.%f').replace(tzinfo=datetime.timezone.utc)
>>> date_time_obj.tzname()
'UTC'

Ran into this exact problem.

What I ended up doing:

# starting with date string
sdt = "20190901"
std_format = '%Y%m%d'

# create naive datetime object
from datetime import datetime
dt = datetime.strptime(sdt, sdt_format)

# extract the relevant date time items
dt_formatters = ['%Y','%m','%d']
dt_vals = tuple(map(lambda formatter: int(datetime.strftime(dt,formatter)), dt_formatters))

# set timezone
import pendulum
tz = pendulum.timezone('utc')

dt_tz = datetime(*dt_vals,tzinfo=tz)

Your time string is similar to the time format in rfc 2822 (date format in email, http headers). You could parse it using only stdlib:

>>> from email.utils import parsedate_tz
>>> parsedate_tz('Tue Jun 22 07:46:22 EST 2010')
(2010, 6, 22, 7, 46, 22, 0, 1, -1, -18000)

See solutions that yield timezone-aware datetime objects for various Python versions: parsing date with timezone from an email.

In this format, EST is semantically equivalent to -0500. Though, in general, a timezone abbreviation is not enough, to identify a timezone uniquely.