Python datetime & time modules

Python provides two modules datetime and time to work with dates and time.

datetime - module

  • datetime modules provides types like
    • datetime - represents date and time
    • date - only represents date
    • timedelta - difference between two datetime values.
    • time - represents time only
    • timezone - fixed offset from UTC implementation of tzinfo.

create datetime object

from datetime import datetime

obj = datetime(
    year=2022, month=11, day=1,
    hour=23, minute=10, second=58,
    microsecond=100
)

get current datetime

from datetime import datetime

now = datetime.now()
print(now)
# output: 2022-11-02 23:35:28.943015
  • above program gives the current datetime

get current UTC datetime

from datetime import datetime

utc_now = datetime.utcnow()
print(utc_now)
# output: 2022-11-02 18:07:19.646767
  • datetime.utcnow() gives current UTC datetime

get native indian time i.e UTC + 5:30

  • we can use datetime and timedelta from dateime module
from datetime import datetime, timedelta

utc_now = datetime.utcnow()
ist_now = utc_now + timedelta(hours=5, minutes=30)
print(ist_now)
# output: 2022-11-02 23:44:02.068166
  • we can also use timezone from pytz module
from pytz import timezone 
from datetime import datetime

ist_now = datetime.now(timezone("Asia/Kolkata"))
print(ist_now)
# output: 2022-11-02 23:45:11.013421+05:30

convert datetime to "YYY-MM-DD HH:MM:SS"

  • use datetime.strftime to get given format.
from datetime import datetime

now = datetime.now()
str_datetime = now.strptime("%Y-%m-%d %H:%M:%S")
print(str_datetime)
# output: 2022-11-02 23:52:11

convert "YYY-MM-DD HH:MM:SS" to datetime

  • use datetime.strftime to convert string to datetime
from datetime import datetime

dt = datetime.strptime("2022-11-02 23:52:11", "%Y-%m-%d %H:%M:%S")
print(dt)
# output: 2022-11-02 23:52:11

Note: Read more about format codes [i.e %Y, %m, etc] at Python official docs

difference between two datetime objects

from datetime import datetime

d1 = datetime(2022, 1, 3)
d2 = datetime(2022, 5, 3)

delta = d2 - d1

print(delta)
# output: 120 days, 0:00:00
print(type(delta))
# output: datetime.timedelta
  • above program gives the timedelta between two datetime objects

time - module

  • time module is python's built-in module, used to work with time

epoch - time

  • The Unix epoch (or Unix time or POSIX time or Unix timestamp) is the number of seconds that have elapsed since January 1, 1970 (midnight UTC/GMT), not counting leap seconds (in ISO 8601: 1970-01-01T00:00:00Z).

  • Let's look at below code to get the epoch time

import time

epoch = time.time()

print(epoch)

# output: 1667615933.811202

convert epoch seconds to datetime string

  • use time.ctime(seconds) to covert seconds to datetime string 
import time

seconds = 1000
date_str = time.ctime(seconds)

print(date_str)
# output: 'Thu Jan  1 05:46:40 1970'

pause / delay a execution of a program

  • use time.sleep(seconds) to delay execution.
  • let's see an example
import time

def wait_sec(sec):
    time.sleep(sec)
    print(f'I waited {sec} sec')

wait_sec(10)
# output: I waited 10 sec
  • when we run the above program, it gives the output after 10 sec

measure program performance

  • we can measure the run time of a program using time module.
  • let's look at the code below.
from time import perf_counter, sleep

def wait_5sec():
    sleep(5)

start = perf_counter()
wait_5sec()
end = perf_counter()

run_time = end - start

print(run_time)
# output: 5.005124709000029
  • First, start captures the moment before you call the function. end captures the moment after the function returns. The function’s total execution time took (end - start) seconds.

To read more about time module visit python official docs

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