Basic DateTime Operations in Python

Python has an in-built module named DateTime to deal with dates and times in numerous ways. In this article, we are going to see basic DateTime operations in Python.

There are six main object classes with their respective components in the datetime module mentioned below:

1. datetime.date
2. datetime.time
3. datetime.datetime
4. datetime.tzinfo
5. datetime.timedelta
6. datetime.timezone

Now we will see the program for each of the functions under datetime module mentioned above. 

datetime.date():

We can generate date objects from the date class. A date object represents a date having a year, month, and day.

Syntax:datetime.date( year, month, day)

strftime to print day, month, and year in various formats. Here are some of them are: 

• current.strftime("%m/%d/%y") that prints in month(Numeric)/date/year format
• current.strftime("%b-%d-%Y") that prints in month(abbreviation)-date-year format
• current.strftime("%d/%m/%Y") that prints in date/month/year format
• current.strftime("%B %d, %Y") that prints in month(words) date, year format

from datetime import date

# You can create a date object containing 
# the current date 
# by using a classmethod named today()
current = date.today() 

# print current year, month, and year individually
print("Current Day is :", current.day)
print("Current Month is :", current.month)
print("Current Year is :", current.year)

# strftime() creates string representing date in 
# various formats
print("\n")
print("Let's print date, month and year in different-different ways")
format1 = current.strftime("%m/%d/%y")

# prints in month/date/year format
print("format1 =", format1)
    
format2 =  current.strftime("%b-%d-%Y")
# prints in month(abbreviation)-date-year format
print("format2 =", format2)

format3 = current.strftime("%d/%m/%Y")

# prints in date/month/year format
print("format3 =", format3)
    
format4 =  current.strftime("%B %d, %Y")

# prints in month(words) date, year format
print("format4 =", format4)

Output:

Current Day is : 23
Current Month is : 3
Current Year is : 2021


Let's print date, month and year in different-different ways
format1 = 03/23/21
format2 = Mar-23-2021
format3 = 23/03/2021
format4 = March 23, 2021

datetime.time():

 A time object generated from the time class represents the local time.

Components: 

• hour
• minute
• second
• microsecond
• tzinfo

Syntax: datetime.time(hour, minute, second, microsecond)

Code:

from datetime import time

# time() takes hour, minutes, second,
# microsecond respectively in order 
# if no parameter is passed in time() by default
# it takes 0 
defaultTime = time()

print("default_hour =", defaultTime.hour)
print("default_minute =", defaultTime.minute)
print("default_second =", defaultTime.second)
print("default_microsecond =", defaultTime.microsecond)

# passing parameter in different-different ways
# hour, minute and second respectively is a default
# order
time1= time(10, 5, 25)
print("time_1 =", time1)

# assigning hour, minute and second to respective
# variables
time2= time(hour = 10, minute = 5, second = 25)
print("time_2 =", time2)

# assigning hour, minute, second and microsecond to
# respective variables
time3= time(hour=10, minute= 5, second=25, microsecond=55)
print("time_3 =", time3)

Output:

default_hour = 0
default_minute = 0
default_second = 0
default_microsecond = 0
time_1 = 10:05:25
time_2 = 10:05:25
time_3 = 10:05:25.000055

datetime.datetime():

datetime.datetime() module shows the combination of a date and a time. 

Components: 

• year
• month
• day
• hour
• minute
• second,
• microsecond
• tzinfo

Syntax: datetime.datetime( year, month, day )

                           or

datetime.datetime(year, month, day, hour, minute, second, microsecond)

Current date and time using the strftime() method in different ways:

• strftime("%d") gives current day
• strftime("%m") gives current month
• strftime("%Y") gives current year
• strftime("%H:%M:%S") gives current time in an hour, minute, and second format
• strftime("%m/%d/%Y, %H:%M:%S") gives date and time together

Code:

from datetime import datetime

# now() gives current date and time
current = datetime.now()

# print combinedly
print(current)
print("\n")
print("print each term individually")

day = current.strftime("%d")

# print day
print("day:", day)

month = current.strftime("%m")

# print month
print("month:", month)

year = current.strftime("%Y")

# print year
print("year:", year)

time = current.strftime("%H:%M:%S")

# time in hour, minute and second
print("time:", time)

print("\n")
print("printing date and time together")
date_time = current.strftime("%m/%d/%Y, %H:%M:%S")
print("date and time:", date_time)
print("\n")

# fetching details from timestamp
timestamp = 1615797322
date_time = datetime.fromtimestamp(timestamp)

# %c, %x and %X are used for locale's proper date and time representation
time_1 = date_time.strftime("%c")
print("first_output:", time_1)

time_2 = date_time.strftime("%x")
print("second_output:", time_2)

time_3 = date_time.strftime("%X")
print("third_output:", time_3)

print("\n")

# assigning each term manually
manual = datetime(2021, 3, 28, 23, 55, 59, 342380)
print("year =", manual.year)
print("month =", manual.month)
print("hour =", manual.hour)
print("minute =", manual.minute)
print("timestamp =", manual.timestamp())

Output:

2021-03-23 19:00:20.726833


print each term individually
day: 23
month: 03
year: 2021
time: 19:00:20


printing date and time together
date and time: 03/23/2021, 19:00:20


first_output: Mon Mar 15 14:05:22 2021
second_output: 03/15/21
third_output: 14:05:22


year = 2021
month = 3
hour = 23
minute = 55
timestamp = 1616955959.34238

datetime.timedelta():

It shows a duration that expresses the difference between two date, time, or datetime instances to microsecond resolution.

Here we implemented some basic functions and printed past and future days. Also, we will print some other attributes of timedelta max, min, and resolution that show maximum days and time, minimum date and time, and the smallest possible difference between non-equal timedelta objects respectively. Here we will also apply some arithmetic operations on two different dates and times.

from datetime import timedelta, datetime

present_date_with_time = datetime.now() 

print("Present Date :", present_date_with_time)

# coming date after 10 days
ten_days_after= present_date_with_time + timedelta(days = 10)
print('Date after 10 days :',ten_days_after)

# date before 10 days
ten_days_before= present_date_with_time - timedelta(days = 10)
print('Date before 10 days :',ten_days_before)

# date before one year ago
one_year_before_today= present_date_with_time + timedelta(days = 365)
print('One year before present Date :', one_year_before_today)

#date before one year ago
one_year_after_today= present_date_with_time - timedelta(days = 365)
print('One year before present Date :', one_year_after_today)

print("\n")
print("print some other attributes of timedelta\n")

# maximum days and time
print("Max : ",timedelta.max)

# minimum days and time
print("Min : ",timedelta.min)

# The smallest possible difference between non-equal
# timedelta objects, timedelta(microseconds=1)
print("Resolution: ",timedelta.resolution)

print('Total number of seconds in an year :', 
      timedelta(days = 365).total_seconds())

print("\nApply some operations on timedelta function\n")
time_after_one_min = present_date_with_time + timedelta(seconds=10) * 6
print('Time after one minute :', time_after_one_min)

print('Timedelta absolute value :', abs(timedelta(days = +20)))

print('Timedelta string representation :', str(timedelta(days = 5,
                       seconds = 40, hours = 20, milliseconds = 355)))

print('Timedelta object representation :', repr(timedelta(days = 5, 
                       seconds = 40, hours = 20, milliseconds = 355)))

Output:

Present Date : 2021-03-25 22:34:27.651128

Date after 10 days : 2021-04-04 22:34:27.651128

Date before 10 days : 2021-03-15 22:34:27.651128

One year before present Date : 2022-03-25 22:34:27.651128

One year before present Date : 2020-03-25 22:34:27.651128

print some other attributes of timedelta

Max :  999999999 days, 23:59:59.999999

Min :  -999999999 days, 0:00:00

Resolution:  0:00:00.000001

Total number of seconds in an year : 31536000.0

Apply some operations on timedelta function

Time after one minute : 2021-03-25 22:35:27.651128

Timedelta absolute value : 20 days, 0:00:00

Timedelta string representation : 5 days, 20:00:40.355000

Timedelta object representation : datetime.timedelta(days=5, seconds=72040, microseconds=355000)

datetime.tzinfo():

It is an abstract base class for time zone information objects. They are used by the datetime and time classes to provide a customizable notion of time adjustment. 

There are the following four methods available for tzinfo base class:

• utcoffset(self, dt): returns the offset of the datetime instance passed as an argument
• dst(self, dt): dst stands for Daylight Saving Time. dst denotes advancing the clock 1 hour in summer so that darkness falls later according to the clock.  It is set to on or off. It is checked on the basis of the following elements:

(dt.year, dt.month, dt.day, dt.hour, dt.minute, dt.second, dt.weekday(), 0, 0)

• tzname(self, dt): It returns a Python String object. It is used to find the time zone name of the datetime object passed.
• fromutc(self, dt) : This function returns the equivalent local time and takes up the date and time of the object in UTC. It is mostly used to adjust the date and time. It is called from default datetime.astimezone() implementation. The dt.tzinfo will be passed as self, dst date and time data will be returned as an equivalent local time.

Note: It raises ValueError if dt.tzinfo is not self or/and dst() is None.

# code
from datetime import datetime, timedelta
from pytz import timezone
import pytz

time_zone = timezone('Asia/Calcutta')

normal = datetime(2021, 3, 16)
ambiguous = datetime(2021, 4, 16, 23, 30)

# is_dst parameter is ignored for most of the
# timstamps.It is only used during DST
# transition ambiguous periods to resolve that
# ambiguity
print("Operations on normal datetime")
print(time_zone.utcoffset(normal, is_dst=True))
print(time_zone.dst(normal, is_dst=True))
print(time_zone.tzname(normal, is_dst=True))

# put is_dst=False
print(time_zone.utcoffset(normal, is_dst=False))
print(time_zone.dst(normal, is_dst=False))
print(time_zone.tzname(normal, is_dst=False))

print("\n")
print("Operations on ambiguous datetime")
print(time_zone.utcoffset(ambiguous, is_dst=True))
print(time_zone.dst(ambiguous, is_dst=True))
print(time_zone.tzname(ambiguous, is_dst=True))

# is_dst=False
print(time_zone.utcoffset(ambiguous, is_dst=False))
print(time_zone.dst(ambiguous, is_dst=False))
print(time_zone.tzname(ambiguous, is_dst=False))

Operations on normal datetime
5:30:00
0:00:00
IST
5:30:00
0:00:00
IST


Operations on ambiguous datetime
5:30:00
0:00:00
IST
5:30:00
0:00:00
IST

Output:

Operations on normal datetime
5:30:00
0:00:00
IST
5:30:00
0:00:00
IST


Operations on ambiguous datetime
5:30:00
0:00:00
IST
5:30:00
0:00:00
IST

datetime.timezone():

Description: It is a class that implements the tzinfo abstract base class as a fixed offset from the UTC.

Syntax: datetime.timezone()

from datetime import datetime, timedelta
from pytz import timezone
import pytz

utc = pytz.utc
print(utc.zone)

india = timezone('Asia/Calcutta')
print(india.zone)

eastern = timezone('US/Eastern')
print(eastern.zone)

time_format = '%Y-%m-%d %H:%M:%S %Z%z'

# localize() is used to localize
# datetime with no timezone information
loc_dt = india.localize(datetime(2021, 3, 16, 6, 0, 0))
loc_dt = india.localize(datetime(2021, 3, 16, 6, 0, 0))
print(loc_dt.strftime(time_format))

# another way of building a localized time is by converting
# an existing localized time 
# using the standard astimezone() method
eastern_dt = loc_dt.astimezone(eastern)
print(eastern_dt.strftime(time_format))

print(datetime(2021, 3, 16, 12, 0, 0, tzinfo=pytz.utc).strftime(time_format))

# 10 minutes before
before_dt = loc_dt - timedelta(minutes=10)
print(before_dt.strftime(time_format))
print(india.normalize(before_dt).strftime(time_format))

# 20 mins later
after_dt = india.normalize(before_dt + timedelta(minutes=20))
print(after_dt.strftime(time_format))

Output:

UTC
Asia/Calcutta
US/Eastern
2021-03-16 06:00:00 IST+0530
2021-03-15 20:30:00 EDT-0400
2021-03-16 12:00:00 UTC+0000
2021-03-16 05:50:00 IST+0530
2021-03-16 05:50:00 IST+0530
2021-03-16 06:10:00 IST+0530

Let's see different Functions with description under time module :-

Now we will see the program and output for each of the above-mentioned functions in the table.

1: time( ) method: The time() method returns the time as a floating-point number expressed in seconds since the epoch, in UTC.

Syntax: time.time([ ])

NOTE: It does not have any parameter

# import time 
import time

#prints total number of seconds passed since epoch
print(time.time())

Output:

1616692391.3081982

2: ctime( ) method 

ctime() method converts a time expressed in seconds since the epoch to a string representing local time. The current time as returned by time() is used If secs is not provided or None. This method is equivalent to asctime(localtime(secs)). Locale information is not used by ctime() method.

Syntax: time.ctime([ sec ])

Where sec passed as an argument is the number of seconds to be converted Into string representation.

import time

number_of_seconds=1625925769.9618232

# function takes seconds passed since epoch as an argument and returns
# a string representing local time
print(time.ctime(number_of_seconds))

Sat Jul 10 14:02:49 2021

3: sleep( ) method

Python time method sleep() stops execution for the given number of seconds. The floating-point the number can be passed as an argument to get more precise sleep time.

Syntax: time.sleep([ sec ])

where sec passed as an argument is the number of seconds for which

the process is to be stopped.

import time

# prints GEEKSFORGEEKS immediately
print("GEEKSFORGEEKS")

time.sleep(1.23)

# prints GEEKSFORGEEKS after 1.23 seconds
# as it stops execution for that time interval
print("GEEKSFORGEEKS")

GEEKSFORGEEKS
GEEKSFORGEEKS

4: localtime( ) method

localtime() method converts number of seconds to local time. If secs is not provided or None, the current time as returned by time() is used. The dst flag is set to 1 when DST applies to the given time.

Syntax: time.localtime([ sec ])

Where sec passed as an argument is the number of seconds to be converted into struct_time representation.

import time

# returns a time.struct_time
# object with a named tuple interface
print(time.localtime())

Output

time.struct_time(tm_year=2021, tm_mon=3, tm_mday=30, tm_hour=8, tm_min=48, tm_sec=58, tm_wday=1, tm_yday=89, tm_isdst=0)

5: gmtime( ) method.

gmtime() method converts a time expressed in seconds since the Epoch to a struct_time in UTC in which the dst flag is always zero. If secs is not provided or None, the current time as returned by time() is used.

Syntax: time.gmtime([ sec ])

Where sec passed as an argument is the number of seconds to be converted into structure struct_time representation.

# code
import time
# returns a time.struct_time object with a named tuple interface
# If secs is not provided or None,
# the current time as returned by time() is used
print(time.gmtime())

Output:

time.struct_time(tm_year=2021, tm_mon=3, tm_mday=30, tm_hour=8, tm_min=49, tm_sec=18, tm_wday=1, tm_yday=89, tm_isdst=0)

6: mktime( ) method

It is the inverse function of localtime() method. It takes an argument as struct_time or full 9-tuple and it returns a floating-point number.  If the input value is not represented as a valid time, then either OverflowError or ValueError is raised.

Syntax: time.mktime([t])

Where t passed as an argument is a time.struct_time object or a tuple containing 9 elements corresponding to time.struct_time object

# code
import time

# method mktime() is the inverse function of localtime()
# Its argument is the struct_time or full 9-tuple and 
# it returns a floating point number, for compatibility with time().

t = (2016, 2, 15, 10, 13, 38, 1, 48, 0)
d = time.mktime(t)
print ("time.mktime(t) : %f" %  d)
print ("asctime(localtime(secs)): %s" % time.asctime(time.localtime(d)))

time.mktime(t) : 1455531218.000000
asctime(localtime(secs)): Mon Feb 15 10:13:38 2016

7: asctime( ) method

Python time method asctime() converts a struct_time representing a time as returned by gmtime() or localtime() to a 24-character string of the following form: 'Tue Mar 23 23:21:05 2021'.

Syntax: time.asctime([t])

Where t passed as an argument is a tuple of 9 elements or struct_time representing a time as returned by gmtime() or localtime() function.

import time
# method returns 24-character string of 
# the following form − 'Mon March 15 23:21:05 2021'

local_time = time.localtime()
print ("asctime : ",time.asctime(local_time))

asctime :  Tue Mar 16 06:02:42 2021