Why %z is not supported by python's strptime?

Question

>>> datetime.strptime('2014-02-13 11:55:00 -0800', '%Y-%m-%d %H:%M:%S %z')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/_strptime.py", line 317, in _strptime
    (bad_directive, format))
ValueError: 'z' is a bad directive in format '%Y-%m-%d %H:%M:%S %z'

I understand that it's not supported, but don't know why. Seems it's not hard to support that. And 'Offset from UTC' is not as ambiguous as timezone abbreviation.

Duplicate: http://stackoverflow.com/questions/1101508/how-to-parse-dates-with-0400-timezone-string-in-python — Ian Stevens, May 29 '14 at 18:43
There's some speculation under a comment in that link. The linked mailing list archive, https://mail.python.org/pipermail/python-bugs-list/2003-November/021063.html, suggests it's a feature of libc: "it's not a Python bug but a bug in the platform libc." Whether or not that's still true, I don't know. — Ian Stevens, May 29 '14 at 18:48
That's a bug report about `time.strptime()` though. The reliance on the libc parser has long since been replaced by a [pure-Python implementation](http://hg.python.org/cpython/file/90dab7696e89/Lib/_strptime.py) used by both the `time.strptime()` and `datetime.datetime.strptime()` functions. — Martijn Pieters, May 29 '14 at 23:26

score 5 · Accepted Answer · answered May 29 '14 at 18:43

Until Python 3.2, Python's datetime module had no timezone() object. It supported 3rd-party libraries providing timezones by providing a datetime.tzinfo() abstract base class, but no timezone object was included. Without a timezone object, no support for parsing timezone offsets either.

As of Python 3.2, z is supported, because that version (and up) added a datetime.timezone() type:

>>> import datetime
>>> datetime.datetime.strptime('2014-02-13 11:55:00 -0800', '%Y-%m-%d %H:%M:%S %z')
datetime.datetime(2014, 2, 13, 11, 55, tzinfo=datetime.timezone(datetime.timedelta(-1, 57600)))
>>> _.tzinfo
datetime.timezone(datetime.timedelta(-1, 57600))

Uri Goren · Answer 2 · 2019-02-08T19:10:12.807

Here is a fix for python 2.7

Instead of using:

datetime.strptime(t,'%Y-%m-%dT%H:%M %z')

use the timedelta to account for the timezone, like this:

from datetime import datetime,timedelta
def dt_parse(t):
    ret = datetime.strptime(t[0:16],'%Y-%m-%dT%H:%M')
    if t[18]=='+':
        ret+=timedelta(hours=int(t[19:22]),minutes=int(t[23:]))
    elif t[18]=='-':
        ret-=timedelta(hours=int(t[19:22]),minutes=int(t[23:]))
    return ret

Why %z is not supported by python's strptime?

2 Answers2

Linked