JD SolankiPython and Managing Date and Time
Naive vs timezone aware datetime
Naive datetime doesn't have any timezone information. Aware datetime has timezone information.
datetime.date
py
import datetime
d = datetime.date(2023, 9, 20) # (year, month, date) 20th September 2023
# ❗ Leading zero may give error: datetime.date(2023, 09, 20) => Error
# get today
today = datetime.date.today()
print(today) # 2023-09-20
print(today.year) # 2023
print(today.month) # 9
print(today.day) # 20
'''
Week day
(on 2023-09-20 it's Wednesday)
`weekday` => Monday = 0, Sunday = 6
`isoweekday` => Monday = 1, Sunday = 7
'''
print(today.weekday()) # 2
print(today.isoweekday()) # 3datetime.timedelta
py
import datetime
today = datetime.date.today()
delta_1_day = datetime.timedelta(days=1)
print(today + delta_1_day) # 2023-09-21
'''
date - date = timedelta
date + timedelta = date
date - timedelta = date
timedelta + timedelta = timedelta
'''
my_birthday_next_year = datetime.date(2024, 1, 28)
delta_till_birthday = my_birthday_next_year - today
print(delta_till_birthday) # 130 days, 0:00:00 (130 days left in my birthday)
print(delta_till_birthday.days) # 130datetime.time
Less used compared to others
py
import datetime
t = datetime.time(9, 30, 45, 100000)
print(t.hour) # 9datetime.datetime
py
import datetime
dt = datetime.datetime(2023, 9, 20, 9, 30, 45, 100000)
print(dt) # 2023-09-20 09:30:45.100000
print(dt.date()) # 2023-09-20
print(dt.time()) # 09:30:45.100000
print(dt.year) # 2023
delta_1_day = datetime.timedelta(days=1)
print(dt + delta_1_day) # 2023-09-21 09:30:45.100000
delta_12_hours = datetime.timedelta(hours=12)
print(dt + delta_12_hours) # 2023-09-20 21:30:45.100000today vs now vs utcnow
py
import datetime
dt_today = datetime.datetime.today()
dt_now = datetime.datetime.now()
dt_utcnow = datetime.datetime.utcnow()
print(dt_today) # 2023-09-20 09:04:31.564997
print(dt_now) # 2023-09-20 09:04:31.565011
print(dt_utcnow) # 2023-09-20 03:34:31.565013
'''
`dt_today` & `dt_now` are almost same because execute at same time.
The difference: `.today()` returns current local datetime with timezone set to `None` whereas `.now()` allows us to pass timezone.
Hence, if you leave timezone empty for both they will be same.
'''
# `dt_utcnow` is still naive datetime. It doesn't have timezone information.pytz and timezone aware datetime
INFO
pytz is third-party module that is recommend by python itself in their docs.
py
import datetime
import pytz
dt = datetime.datetime(2023, 9, 20, 9, 30, 45, 100000, tzinfo=pytz.UTC)
print(dt) # 2023-09-20 09:30:45.100000+00:00
# Current UTC time that is timezone aware
dt_now = datetime.datetime.now(tz=pytz.UTC) # ℹ️ Recommended
print(dt_now) # 2023-09-20 08:49:21.452949+00:00
dt_uctnow = datetime.datetime.utcnow().replace(tzinfo=pytz.UTC)
print(dt_uctnow) # 2023-09-20 08:49:21.453095+00:00
'''
`dt_now` & `dt-utcnow` is identical because both are timezone aware.
`dt_now` is recommended though.
'''
dt_india = dt_now.astimezone(pytz.timezone('Asia/Kolkata'))
print(dt_india) # 2023-09-20 14:22:36.130913+05:30Get list of available timezones
py
for tz in pytz.all_timezones:
print(tz)How to make naive datetime, timezone aware
Refer to this snippet.
TIP
Use iso format to pass datetime around or for saving. Refer to this tip.
Printing datetime & Converting back
strftime=> datetime to stringstrptime=> string to datetime
Printing or converting datetime to string
You can use strftime method to print datetime in any format you want. Check out all format codes with example in official python docs.
py
import datetime
import pytz
# local time without timezone info
dt_india = datetime.datetime.now(tz=pytz.timezone('Asia/Kolkata'))
print(dt_india.isoformat())
print(dt_india.strftime('%B %d, %Y')) # September 20, 2023Convert string datetime to datetime object
py
import datetime
dt_str = 'September 20, 2023'
# Use `strptime` to convert string datetime to datetime object
# Second argument is what format that string is in
dt = datetime.datetime.strptime(dt_str, '%B %d, %Y')
print(dt) # 2023-09-20 00:00:00