Everything about date & time in python

Posted on 02 Apr, 2021

Earth rotates just like my head trying to understand dates and time-zones.

Get current date & time

>>> import datetime
# without timezone
>>> datetime.datetime.now().strftime("%d %b, %Y (%I:%M:%S %p)")
'02 Apr, 2021 (01:37:43 PM)'

# with local timezone
>>> datetime.datetime.now(datetime.timezone.utc).astimezone().strftime("%d %b, %Y (%I:%M:%S %p) %Z")
'02 Apr, 2021 (01:38:20 PM) IST'

Current date/time to Unix timestamp

>>> import time
>>> t = datetime.datetime.now(datetime.timezone.utc).astimezone()
>>> t.timetuple()
time.struct_time(tm_year=2021, tm_mon=4, tm_mday=2, tm_hour=13, tm_min=43, tm_sec=15, tm_wday=4, tm_yday=92, tm_isdst=-1)
>>> time.mktime(t.timetuple())
1617351195.0

Unix timestamp to date/time

>>> import time
>>> t = datetime.datetime.now(datetime.timezone.utc).astimezone()
>>> unix_t = time.mktime(t.timetuple())
1617351195.0
>>> t = time.localtime(unix_t)
time.struct_time(tm_year=2021, tm_mon=4, tm_mday=2, tm_hour=13, tm_min=46, tm_sec=32, tm_wday=4, tm_yday=92, tm_isdst=0)
# verify
>>> time.strftime("%d %b, %Y (%I:%M:%S %p)", t)
'02 Apr, 2021 (01:46:32 PM IST)'

datetime object to string

>>> from datetime import datetime
>>> d = datetime.now()
>>> d
datetime.datetime(2020, 11, 7, 20, 15, 58, 389341)
>>> d.strftime("%d %b, %Y")
'07 Nov, 2020'

From string to datetime object

>>> from datetime import datetime
>>> date_string = "2020-06-20T08:22:54Z"
>>> datetime.strptime(date_string, '%Y-%m-%dT%H:%M:%SZ')
datetime.datetime(2020, 6, 20, 8, 22, 54)

Both strptime & strftime can ofc be chained.

>>> from datetime import datetime
>>> date_string = "2020-06-20T08:22:54Z"
>>> datetime.strptime(date_string, '%Y-%m-%dT%H:%M:%SZ').strftime("%d %b, %Y")

This can be handy when you are getting date/time fields from external resource (like an API) and only want to display a part of it (like days, month etc).

Format codes for strptime and strftime

Directive	Meaning	Example
%a	Weekday as locale’s abbreviated name.	Sun, Mon, …, Sat (en_US);So, Mo, …, Sa (de_DE)
%A	Weekday as locale’s full name.	Sunday, Monday, …, Saturday (en_US);Sonntag, Montag, …, Samstag (de_DE)
%w	Weekday as a decimal number, where 0 is Sunday and 6 is Saturday.	0, 1, …, 6
%d	Day of the month as a zero-padded decimal number.	01, 02, …, 31
%b	Month as locale’s abbreviated name.	Jan, Feb, …, Dec (en_US);Jan, Feb, …, Dez (de_DE)
%B	Month as locale’s full name.	January, February, …, December (en_US);Januar, Februar, …, Dezember (de_DE)
%m	Month as a zero-padded decimal number.	01, 02, …, 12
%y	Year without century as a zero-padded decimal number.	00, 01, …, 99
%Y	Year with century as a decimal number.	0001, 0002, …, 2013, 2014, …, 9998, 9999
%H	Hour (24-hour clock) as a zero-padded decimal number.	00, 01, …, 23
%I	Hour (12-hour clock) as a zero-padded decimal number.	01, 02, …, 12
%p	Locale’s equivalent of either AM or PM.	AM, PM (en_US);am, pm (de_DE)
%M	Minute as a zero-padded decimal number.	00, 01, …, 59
%S	Second as a zero-padded decimal number.	00, 01, …, 59
%f	Microsecond as a decimal number, zero-padded on the left.	000000, 000001, …, 999999
%z	UTC offset in the form ±HHMM[SS[.ffffff]] (empty string if the object is naive).	(empty), +0000, -0400, +1030, +063415, -030712.345216
%Z	Time zone name (empty string if the object is naive).	(empty), UTC, GMT
%j	Day of the year as a zero-padded decimal number.	001, 002, …, 366
%U	Week number of the year (Sunday as the first day of the week) as a zero padded decimal number. All days in a new year preceding the first Sunday are considered to be in week 0.	00, 01, …, 53
%W	Week number of the year (Monday as the first day of the week) as a decimal number. All days in a new year preceding the first Monday are considered to be in week 0.	00, 01, …, 53
%c	Locale’s appropriate date and time representation.	Tue Aug 16 21:30:00 1988 (en_US);Di 16 Aug 21:30:00 1988 (de_DE)
%x	Locale’s appropriate date representation.	08/16/88 (None);08/16/1988 (en_US);16.08.1988 (de_DE)
%X	Locale’s appropriate time representation.	21:30:00 (en_US);21:30:00 (de_DE)
%%	A literal '%' character.	%