How to force python print numpy datetime64 with specified timezone?

Question

I want to see numpy datetime64 objects by my specified timezone.

>>> import numpy as np
>>> np.datetime64('2013-03-10T01:30:54')
numpy.datetime64('2013-03-10T01:30:54+0400')
>>> np.datetime64('2013-03-10T01:30:54+0300')
numpy.datetime64('2013-03-10T02:30:54+0400')

Python prints datetime objects always in UTC+0400 (it is my local timezone) even if I specify another timezone >>> np.datetime64('2013-03-10T01:30:54+0300'). Is there a way to force python print by UTC+0000 timezone?

I am using numpy 1.8.1 .

Answer 1

Mentioned a few times in the numpy documentation:

The datetime object represents a single moment in time.

...

Datetimes are always stored based on POSIX time ...

So, internally a datetime64 is tracking a single integer, which represents a moment in time as a value since the UNIX epoch (1970-01-01) - not counting leap seaconds.

Therefore, time zones are not preserved. If you pass in a time zone offset, it will apply it to determine the correct UTC time. If you don't pass one, it will use the local machine's time zone. Regardless of input, on output it uses the local machine's time zone to project the UTC time to a local time with offset.

Answer 2

Is there a way to force python print by UTC+0000 timezone?

You could call .item() that returns a naive datetime object that represents time in UTC on data in your example:

>>> import numpy
>>> numpy.__version__
'1.8.1'
>>> dt = numpy.datetime64('2013-03-10T01:30:54+0300')
>>> dt
numpy.datetime64('2013-03-10T02:30:54+0400')
>>> dt.item()
datetime.datetime(2013, 3, 9, 22, 30, 54)
>>> print(dt.item())
2013-03-09 22:30:54

Answer 3

You could always set the time zone before printing your datetime64 objects:

>>> import os, time, numpy
>>> os.environ['TZ'] = 'GMT'
>>> time.tzset()

>>> numpy.datetime64(0, 's')
numpy.datetime64('1970-01-01T00:00:00+0000')