I have a datetime in utc time zone, for example:
utc_time = datetime.datetime.utcnow()
And a pytz timezone object:
tz = timezone('America/St_Johns')
What is the proper way to convert utc_time to the given timezone?
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related: How to convert a python utc datetime to a local datetime using only python standard library?jfs– jfs2014-08-31 17:00:42 +00:00Commented Aug 31, 2014 at 17:00
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6 Answers
I think I got it:
pytz.utc.localize(utc_time, is_dst=None).astimezone(tz)
This line first converts the naive (time zone unaware) utc_time datetime object to a datetime object that contains a timezone (UTC). Then it uses the astimezone function to adjust the time according to the requested time zone.
7 Comments
jfs
utc_time.replace(tzinfo=pytz.utc).astimezone(tz). Note: pytz.utc is a special case (zero utc offset, always). You don't need localize() call in this case. If you do keep it (for generality); then add tz.normalize() call around the expression (it might be necessary if the source timezone is not UTC).
Tzach
@J.F.Sebastian the call to
localize is needed because utc_time doesn't contain timezone information. Without it astimezone won't work.jfs
@Tzach what do you think the
replace() call does in my previous comment?
Yingding Wang
It works also for utc_timestamp as int with datetime.utcfromtimestamp(utc_timestamp), which returns a timezone not aware datetime object. But utc_time.replace doesn't do the time schift and only add a tzinfo.
CrackerJack9
@YingdingWang The question from almost 5 years ago is not using
utcfromtimestamp. Also datetime.datetime.utcnow() sets tzinfo as None. |
It's the exact purpose of fromutc function:
tz.fromutc(utc_time)
(astimezone function calls fromutc under the hood, but tries to convert to UTC first, which is unneeded in your case)
Comments
I agree with Tzach's answer. Just wanted to include that the is_dst parameter is not required:
pytz.utc.localize(datetime.utcnow()).astimezone(tz)
That code converts the current UTC time to a timezone aware current datetime.
Whereas the code below converts the current UTC time to a timezone aware datetime which is not necessarily current. The timezone is just appended into the UTC time value.
tz.localize(datetime.utcnow())
2 Comments
qris
If you already have a timezone-aware datetime, then you just need to use
astimezone: dt.astimezone(tz). See also this answer and the pytz docs.
Rufflewind
user8808265's answer is much simpler.
May I recommend to use arrow? If I understood the question:
>>> import arrow
>>> utc = arrow.utcnow()
>>> utc
<Arrow [2014-08-12T13:01:28.071624+00:00]>
>>> local = utc.to("America/St_Johns")
>>> local
<Arrow [2014-08-12T10:31:28.071624-02:30]>
You can also use
tz.fromutc(utc_time)
1 Comment
Tzach
Thank you. This library indeed looks as a good alternative to
datetime, however my project is big and I don't want to create more confusion by using another date-time library. I will definitely consider using it in other projects.Another very easy way:
Because utcnow method returns a naive object, so you have to convert the naive object into aware object. Using replace method you can convert a naive object into aware object. Then you can use the astimezone method to create new datetime object in a different time zone.
from datetime import datetime
import pytz
utc_time = datetime.utcnow()
tz = pytz.timezone('America/St_Johns')
utc_time =utc_time.replace(tzinfo=pytz.UTC) #replace method
st_john_time=utc_time.astimezone(tz) #astimezone method
print(st_john_time)
1 Comment
paolov
replace method is a bad idea. It is random in its behaviour
You can also use the sample below, I use it for similar task
tz = pytz.timezone('America/St_Johns')
time_difference=tz.utcoffset(utc_time).total_seconds() #time difference between UTC and local timezones in 5:30:00 format
utc_time = date + timedelta(0,time_difference)
It works fast and you don't need to import additional libraries.
1 Comment
qris
This is wrong for timezones with daylight savings, because it doesn't account for them. See this answer.