Python datetime strptime and strftime how to preserve the timezone information

Question

See the following code    import datetime import pytz  fmt     Y- m- d  H  M  S  Z   d   datetime datetime now pytz timezone  America New York    d string   d strftime fmt  d2   datetime datetime strptime d string  fmt  print d string  print d2 strftime fmt    the output is   2013-02-07 17 42 31 EST 2013-02-07 17 42 31    The timezone information simply got lost in the translation    If I switch   Z  to   z   I get  ValueError   z  is a bad directive in format   Y- m- d  H  M  S  z    I know I can use python-dateutil  but I just found it bizzare that I can t achieve this simple feature in datetime and have to introduce more dependency

User · Accepted Answer

Part of the problem here is that the strings usually used to represent timezones are not actually unique. "EST" only means "America/New_York" to people in North America. This is a limitation in the C time API, and the Python solution is… to add full tz features in some future version any day now, if anyone is willing to write the PEP.

You can format and parse a timezone as an offset, but that loses daylight savings/summer time information (e.g., you can't distinguish "America/Phoenix" from "America/Los_Angeles" in the summer). You can format a timezone as a 3-letter abbreviation, but you can't parse it back from that.

If you want something that's fuzzy and ambiguous but usually what you want, you need a third-party library like dateutil.

If you want something that's actually unambiguous, just append the actual tz name to the local datetime string yourself, and split it back off on the other end:

d = datetime.datetime.now(pytz.timezone("America/New_York"))
dtz_string = d.strftime(fmt) + ' ' + "America/New_York"

d_string, tz_string = dtz_string.rsplit(' ', 1)
d2 = datetime.datetime.strptime(d_string, fmt)
tz2 = pytz.timezone(tz_string)

print dtz_string 
print d2.strftime(fmt) + ' ' + tz_string

Or… halfway between those two, you're already using the pytz library, which can parse (according to some arbitrary but well-defined disambiguation rules) formats like "EST". So, if you really want to, you can leave the %Z in on the formatting side, then pull it off and parse it with pytz.timezone() before passing the rest to strptime.

User · Answer

Unfortunately  strptime   can only handle the timezone configured by your OS  and then only as a time offset  really  From the documentation      Support for the  Z directive is based on the values contained in tzname and whether daylight is true  Because of this  it is platform-specific except for recognizing UTC and GMT which are always known  and are considered to be non-daylight savings timezones     strftime   doesn t officially support  z    You are stuck with python-dateutil to support timezone parsing  I am afraid

User · Answer

Try this  import pytz import datetime  fmt     Y- m- d  H  M  S  Z   d   datetime datetime now pytz timezone  quot America New York quot    d string   d strftime fmt  d2   pytz timezone  America New York   localize d strptime d string fmt   is dst None  print d string  print d2 strftime fmt

User · Answer

Here is my answer in Python 2 7  Print current time with timezone  from datetime import datetime import tzlocal    pip install tzlocal  print datetime now tzlocal get localzone    strftime   Y- m- d  H  M  S  z     Print current time with specific timezone  from datetime import datetime import pytz   pip install pytz  print datetime now pytz timezone  Asia Taipei    strftime   Y- m- d  H  M  S  z     It will print something like  2017-08-10 20 46 24  0800

[python] Python datetime strptime() and strftime(): how to preserve the timezone information

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