pytz: get integer utc offset from Olsen region/city

[h4tt3n]

Hello folks,

Newbie Python programmer here. I am just beginning to learn the pytz time zone module.

Can you please explain how I get an UTC offset integer value from an Olsen / IANA timezone with the "region/city" format?

For example, I would like to get the integer value "2" as output from the input "Europe/Copenhagen", because this timezone is UTC+2 (during daylight saving, else UTC+1)

Cheers, and thanks in advance!

Mike

[bowlofred]

The offset depends on when you are asking (can be affected by daylight saving time). So you must supply a reference time. datetime.now() will work if you are interested in the offset when the program runs.

Given that, you can ask for the utcoffset, put it all into seconds, then divide by the number of seconds in an hour.

>>> cop_tz = timezone('Europe/Copenhagen')
>>> cop_tz.utcoffset(datetime.now()).total_seconds() / (60*60)       # "Now" is during summer/DST
2.0
>>> cop_tz.utcoffset(datetime(2020, 1, 1, 0, 0, 0)).total_seconds() / (60*60)     # During winter/ST
1.0
>>> timezone('America/Los_Angeles').utcoffset(datetime.now()).total_seconds() / (60*60)    # Negative/westerly offset
-7.0
>>> timezone('Asia/Kolkata').utcoffset(datetime.now()).total_seconds() / (60*60)       # Noninteger offset
5.5

[h4tt3n]

Thanks, this solves my problem! I forgot that you can't simply translate an IANA / Olson timezone into a UTC offset, because it will vary over time due to daylight saving. You need a specific date/time to get a useful UTC offset.

I also found this link very helpful:
https://stackoverflow.com/questions/2956...m-timezone

import pytz
import datetime

tz = pytz.timezone('Asia/Calcutta')
dt = datetime.datetime.utcnow()

offset_seconds = tz.utcoffset(dt).seconds

offset_hours = offset_seconds / 3600.0

print "{:+d}:{:02d}".format(int(offset_hours), int((offset_hours % 1) * 60))
# +5:30

Cheers, Mike