Get timezone abbreviation from UTC offset

Question

I have the UTC offset in my DB for the users:

+5:30 

How can I get the timezone abbreviation from this UTC offset using Python?

Such as

+5:30 => IST

Is it even possible to do this using Python?

Answer 1

As Matt stated, going from offset to timezone does not make a lot of sense.

In case you were looking to find an appropriate pytz.timezone object for a given offset:

there are timezones ranging from "Etc/GMT-14" to "Etc/GMT+12"

just take a look at pytz.all_timezones.

Using those, I was able to use faulty client input (mistaking timezone for offset) to attach a valid timezone object to my user.

Answer 2

You can get a set (zero or more) of timezone abbreviations (as specified in the tz database) that corresponds to the given UTC offset now:

#!/usr/bin/env python
from datetime import datetime, timedelta
import pytz # $ pip install pytz

utc_offset = timedelta(hours=5, minutes=30) # +5:30
now = datetime.now(pytz.utc) # current time
print({now.astimezone(tz).tzname() 
       for tz in map(pytz.timezone, pytz.all_timezones_set)
       if now.astimezone(tz).utcoffset() == utc_offset})

Output

set(['IST'])

If you want to get abbreviations including the historical data:

#!/usr/bin/env python
from datetime import datetime, timedelta
import pytz # $ pip install pytz

utc_offset = timedelta(hours=5, minutes=30) # +5:30
abbr = set()
now = datetime.now(pytz.utc)
for tz in map(pytz.timezone, pytz.all_timezones_set):
    dt = now.astimezone(tz)    
    tzinfos = getattr(tz, '_tzinfos',
                      [(dt.utcoffset(), dt.dst(), dt.tzname())])
    abbr.update(tzname for off, _, tzname in tzinfos if off == utc_offset)
print(abbr)

Output

set(['IST'])

Answer 3

This is not possible.

• There are many time zones that share the same offset. See this Wikipedia article for details.

• There is no uniform standard for time zone abbreviations. There are some listed here and here, and you can see that there are duplicates in both directions.

  For example:

  • CST might be -5:00, -6:00, +8:00, +9:30 or +10:30.
  • -10:00 could be HST, HAST, TAHT, or CKT

Read also the section "Time Zone != Offset" of the timezone tag wiki here on StackOverflow.