As of Python 3.7, datetime.datetime.fromisoformat() can handle your format:

>>> import datetime
>>> datetime.datetime.fromisoformat('2012-11-01T04:16:13-04:00')
datetime.datetime(2012, 11, 1, 4, 16, 13, tzinfo=datetime.timezone(datetime.timedelta(days=-1, seconds=72000)))

In older Python versions you can't, not without a whole lot of painstaking manual timezone defining.

Python versions before version 3.9 do not include a timezone database, because it would be outdated too quickly. Instead, for those versions Python relied on external libraries, which can have a far faster release cycle, to provide properly configured timezones for you.

As a side-effect, this means that timezone parsing also needs to be an external library. If dateutil is too heavy-weight for you, use iso8601 instead, it'll parse your specific format just fine:

>>> import iso8601
>>> iso8601.parse_date('2012-11-01T04:16:13-04:00')
datetime.datetime(2012, 11, 1, 4, 16, 13, tzinfo=<FixedOffset '-04:00'>)

iso8601 is a whopping 4KB small. Compare that tot python-dateutil's 148KB.

As of Python 3.2 Python can handle simple offset-based timezones, and %z will parse -hhmm and +hhmm timezone offsets in a timestamp. That means that for a ISO 8601 timestamp you'd have to remove the : in the timezone:

>>> from datetime import datetime
>>> iso_ts = '2012-11-01T04:16:13-04:00'
>>> datetime.strptime(''.join(iso_ts.rsplit(':', 1)), '%Y-%m-%dT%H:%M:%S%z')
datetime.datetime(2012, 11, 1, 4, 16, 13, tzinfo=datetime.timezone(datetime.timedelta(-1, 72000)))

The lack of proper ISO 8601 parsing was being tracked in Python issue 15873 (since migrated to GitHub issue #60077).

You can use the parse function from dateutil:

>>> from dateutil.parser import parse
>>> d = parse('2009/05/13 19:19:30 -0400')
>>> d
datetime.datetime(2009, 5, 13, 19, 19, 30, tzinfo=tzoffset(None, -14400))

This way you obtain a datetime object you can then use.

As answered, dateutil2.0 is written for Python 3.0 and does not work with Python 2.x. For Python 2.x dateutil1.5 needs to be used.

You can parse using dateutil package

import dateutil.parser

dateutil.parser.parse('2008-09-03T20:56:35.450686Z')

datetime.datetime(2017, 6, 4, 1, 0, tzinfo=tzoffset(None, 14400))

for install package

pip install python-dateutil

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.

You could use %z to parse timezone info:

>>> from datetime import datetime, timezone
>>> datetime.strptime(str, "%Y-%m-%dT%H:%M:%S%z")
datetime.datetime(2015, 8, 23, 3, 36, 30, tzinfo=datetime.timezone(datetime.timedelta(days=-1, seconds=68400)))

Then, if you want to convert this datetime to UTC (which I assume is your goal since you say you want to compare datetimes), you could use astimezone method:

>>> datetime.strptime(str, "%Y-%m-%dT%H:%M:%S%z").astimezone(timezone.utc)
datetime.datetime(2015, 8, 23, 8, 36, 30, tzinfo=datetime.timezone.utc)

Back in string format:

>>> datetime.strptime(str, "%Y-%m-%dT%H:%M:%S%z").astimezone(timezone.utc).strftime("%Y-%m-%d %H:%M:%S")
'2015-08-23 08:36:30'