Python datetime module (original) (raw)
In Python, date and time are not data types of their own, but a module named **DateTime in Python can be imported to work with the date as well as time. **Python Datetime module comes built into Python, so there is no need to install it externally.
In this article, we will explore How DateTime in Python works and what are the main classes of DateTime module in Python.
Table of Content
- Python DateTime module
- Python Date Class
- Python Time class
- Python Datetime class
- Python Timedelta Class
- Python DateTime.tzinfo()
- Python DateTime timezone
Python DateTime module
**Python Datetime module supplies classes to work with date and time. These classes provide several functions to deal with dates, times, and time intervals. Date and DateTime are an object in Python, so when you manipulate them, you are manipulating objects and not strings or timestamps.
The DateTime module is categorized into 6 main classes –
- **date – An idealized naive date, assuming the current Gregorian calendar always was, and always will be, in effect. Its attributes are year, month, and day. you can refer to – Python DateTime – Date Class
- **time – An idealized time, independent of any particular day, assuming that every day has exactly 24*60*60 seconds. Its attributes are hour, minute, second, microsecond, and tzinfo. You can refer to – Python DateTime – Time Class
- **date-time – It is a combination of date and time along with the attributes year, month, day, hour, minute, second, microsecond, and tzinfo. You can refer to – Python DateTime – DateTime Class
- **timedelta – A duration expressing the difference between two date, time, or datetime instances to microsecond resolution. You can refer to – Python DateTime – Timedelta Class
- **tzinfo – It provides time zone information objects. You can refer to – Python – datetime.tzinfo()
- **timezone – A class that implements the tzinfo abstract base class as a fixed offset from the UTC (New in version 3.2). You can refer to – Handling timezone in Python
Python Date Class
The date class is used to instantiate date objects in Python. When an object of this class is instantiated, it represents a date in the format **YYYY-MM-DD. The constructor of this class needs three mandatory arguments year, month, and date.
**Python Date class Syntax
class datetime.date(year, month, day)
The arguments must be in the following range –
- MINYEAR <= year <= MAXYEAR
- 1 <= month <= 12
- 1 <= day <= number of days in the given month and year
**Note – If the argument is not an integer it will raise a TypeError and if it is outside the range a ValueError will be raised.
Date object representing data in Python
Initializing the constructor and passing arguments in the format year, month, and date.
Python3
from datetime import date
my_date = date( 1996 , 12 , 11 )
print ( "Date passed as argument is" , my_date)
**Output:
Date passed as argument is 1996-12-11
Traceback (most recent call last):
File "/home/ccabfb570d9bd1dcd11dc4fe55fd6ba2.py", line 14, in
my_date = date(1996, 12, 39)
ValueError: day is out of range for month
Traceback (most recent call last):
File "/home/53b974e10651f1853eee3c004b48c481.py", line 18, in
my_date = date('1996', 12, 11)
TypeError: an integer is required (got type str)
Get the Current Date
To return the current local date today() function of the date class is used. today() function comes with several attributes (year, month, and day). These can be printed individually.
Python3
from datetime import date
today = date.today()
print ( "Today's date is" , today)
Output
Today's date is 2021-08-19
Get Today’s Year, Month, and Date
We can get the year, month, and date attributes from the date object using the year, month and date attribute of the date class.
Python3
from datetime import date
today = date.today()
print ( "Current year:" , today.year)
print ( "Current month:" , today.month)
print ( "Current day:" , today.day)
Output
Current year: 2021 Current month: 8 Current day: 19
Get Date from Timestamp
We can create date objects from timestamps y=using the fromtimestamp() method. The timestamp is the number of seconds from 1st January 1970 at UTC to a particular date.
Python3
from datetime import datetime
date_time = datetime.fromtimestamp( 1887639468 )
print ( "Datetime from timestamp:" , date_time)
Output
Datetime from timestamp: 2029-10-25 16:17:48
Convert Date to String
We can convert date object to a string representation using two functions isoformat() and strftime().
Python3
from datetime import date
today = date.today()
Str = date.isoformat(today)
print ( "String Representation" , Str )
print ( type ( Str ))
Output
String Representation 2021-08-19 <class 'str'>
List of Date Class Methods
| Function Name | Description |
|---|---|
| ctime() | Return a string representing the date |
| fromisocalendar() | Returns a date corresponding to the ISO calendar |
| fromisoformat() | Returns a date object from the string representation of the date |
| fromordinal() | Returns a date object from the proleptic Gregorian ordinal, where January 1 of year 1 has ordinal 1 |
| fromtimestamp() | Returns a date object from the POSIX timestamp |
| isocalendar() | Returns a tuple year, week, and weekday |
| isoformat() | Returns the string representation of the date |
| isoweekday() | Returns the day of the week as an integer where Monday is 1 and Sunday is 7 |
| replace() | Changes the value of the date object with the given parameter |
| strftime() | Returns a string representation of the date with the given format |
| timetuple() | Returns an object of type time.struct_time |
| today() | Returns the current local date |
| toordinal() | Return the proleptic Gregorian ordinal of the date, where January 1 of year 1 has ordinal 1 |
| weekday() | Returns the day of the week as integer where Monday is 0 and Sunday is 6 |
Python Time class
The time class creates the time object which represents local time, independent of any day.
**Constructor Syntax:
class datetime.time(hour=0, minute=0, second=0, microsecond=0, tzinfo=None, *, fold=0)
All the arguments are optional. tzinfo can be None otherwise all the attributes must be integer in the following range –
- 0 <= hour < 24
- 0 <= minute < 60
- 0 <= second < 60
- 0 <= microsecond < 1000000
- fold in [0, 1]
Example 1: Time object representing time in Python
Python3
from datetime import time
my_time = time( 13 , 24 , 56 )
print ( "Entered time" , my_time)
my_time = time(minute = 12 )
print ( "\nTime with one argument" , my_time)
my_time = time()
print ( "\nTime without argument" , my_time)
**Output:
Entered time 13:24:56
Time with one argument 00:12:00
Time without argument 00:00:00
Traceback (most recent call last):
File "/home/95ff83138a1b3e67731e57ec6dddef25.py", line 21, in
print(time(hour=26))
ValueError: hour must be in 0..23
Traceback (most recent call last):
File "/home/fcee9ba5615b0b74fc3ba39ec9a789fd.py", line 21, in
print(time(hour='23'))
TypeError: an integer is required (got type str)
Example 2: Get hours, minutes, seconds, and microseconds
After creating a time object, its attributes can also be printed separately.
Python3
from datetime import time
Time = time( 11 , 34 , 56 )
print ( "hour =" , Time.hour)
print ( "minute =" , Time.minute)
print ( "second =" , Time.second)
print ( "microsecond =" , Time.microsecond)
**Output:
hour = 11
minute = 34
second = 56
microsecond = 0
Example 3: Convert Time object to String
We can convert time object to string using the isoformat() method.
Python3
from datetime import time
Time = time( 12 , 24 , 36 , 1212 )
Str = Time.isoformat()
print ( "String Representation:" , Str )
print ( type ( Str ))
Output
String Representation: 12:24:36.001212 <class 'str'>
List of Time class Methods
| Function Name | Description |
|---|---|
| dst() | Returns tzinfo.dst() is tzinfo is not None |
| fromisoformat() | Returns a time object from the string representation of the time |
| isoformat() | Returns the string representation of time from the time object |
| replace() | Changes the value of the time object with the given parameter |
| strftime() | Returns a string representation of the time with the given format |
| tzname() | Returns tzinfo.tzname() is tzinfo is not None |
| utcoffset() | Returns tzinfo.utcffsets() is tzinfo is not None |
Python Datetime class
The DateTime class contains information on both date and time. Like a date object, datetime assumes the current Gregorian calendar extended in both directions; like a time object, datetime assumes there are exactly 3600*24 seconds in every day.
**Constructor Syntax:
class datetime.datetime(year, month, day, hour=0, minute=0, second=0, microsecond=0, tzinfo=None, *, fold=0)
The year, month, and day arguments are mandatory. tzinfo can be None, rest all the attributes must be an integer in the following range –
- MINYEAR <= year <= MAXYEAR
- 1 <= month <= 12
- 1 <= day <= number of days in the given month and year
- 0 <= hour < 24
- 0 <= minute < 60
- 0 <= second < 60
- 0 <= microsecond < 1000000
- fold in [0, 1]
**Note – Passing an argument other than integer will raise a TypeError and passing arguments outside the range will raise ValueError.
DateTime object representing DateTime in Python
Python3
from datetime import datetime
a = datetime( 1999 , 12 , 12 )
print (a)
a = datetime( 1999 , 12 , 12 , 12 , 12 , 12 , 342380 )
print (a)
**Output:
1999-12-12 00:00:00
1999-12-12 12:12:12.342380
Get year, month, hour, minute, and timestamp
After creating a DateTime object, its attributes can also be printed separately.
Python3
from datetime import datetime
a = datetime( 1999 , 12 , 12 , 12 , 12 , 12 )
print ( "year =" , a.year)
print ( "month =" , a.month)
print ( "hour =" , a.hour)
print ( "minute =" , a.minute)
print ( "timestamp =" , a.timestamp())
**Output:
year = 1999
month = 12
hour = 12
minute = 12
timestamp = 945000732.0
Current date and time
You can print the current date and time using the Datetime.now() function. now() function returns the current local date and time.
Python3
from datetime import datetime
today = datetime.now()
print ( "Current date and time is" , today)
**Output:
Current date and time is 2019-10-25 11:12:11.289834
Convert Python Datetime to String
We can convert Datetime to string in Python using the datetime.strftime and datetime.isoformat methods.
Python3
from datetime import datetime as dt
now = dt.now()
string = dt.isoformat(now)
print (string)
print ( type (string))
Output
2021-08-19T18:13:25.346259 <class 'str'>
List of Datetime Class Methods
| Function Name | Description |
|---|---|
| astimezone() | Returns the DateTime object containing timezone information. |
| combine() | Combines the date and time objects and return a DateTime object |
| ctime() | Returns a string representation of date and time |
| date() | Return the Date class object |
| fromisoformat() | Returns a datetime object from the string representation of the date and time |
| fromordinal() | Returns a date object from the proleptic Gregorian ordinal, where January 1 of year 1 has ordinal 1. The hour, minute, second, and microsecond are 0 |
| fromtimestamp() | Return date and time from POSIX timestamp |
| isocalendar() | Returns a tuple year, week, and weekday |
| isoformat() | Return the string representation of date and time |
| isoweekday() | Returns the day of the week as integer where Monday is 1 and Sunday is 7 |
| now() | Returns current local date and time with tz parameter |
| replace() | Changes the specific attributes of the DateTime object |
| strftime() | Returns a string representation of the DateTime object with the given format |
| strptime() | Returns a DateTime object corresponding to the date string |
| time() | Return the Time class object |
| timetuple() | Returns an object of type time.struct_time |
| timetz() | Return the Time class object |
| today() | Return local DateTime with tzinfo as None |
| toordinal() | Return the proleptic Gregorian ordinal of the date, where January 1 of year 1 has ordinal 1 |
| tzname() | Returns the name of the timezone |
| utcfromtimestamp() | Return UTC from POSIX timestamp |
| utcoffset() | Returns the UTC offset |
| utcnow() | Return current UTC date and time |
| weekday() | Returns the day of the week as integer where Monday is 0 and Sunday is 6 |
Python Timedelta Class
Python timedelta class is used for calculating differences in dates and also can be used for date manipulations in Python. It is one of the easiest ways to perform date manipulations.
**Constructor syntax:
class datetime.timedelta(days=0, seconds=0, microseconds=0, milliseconds=0, minutes=0, hours=0, weeks=0)
Returns : Date
Add days to DateTime object
The timedelta function demonstration
Python3
from datetime import datetime, timedelta
ini_time_for_now = datetime.now()
print ( "initial_date" , str (ini_time_for_now))
future_date_after_2yrs = ini_time_for_now + timedelta(days = 730 )
future_date_after_2days = ini_time_for_now + timedelta(days = 2 )
print ( 'future_date_after_2yrs:' , str (future_date_after_2yrs))
print ( 'future_date_after_2days:' , str (future_date_after_2days))
**Output:
initial_date 2019-10-25 12:01:01.227848
future_date_after_2yrs: 2021-10-24 12:01:01.227848
future_date_after_2days: 2019-10-27 12:01:01.227848
Difference between two date and times
Date and Time differences can also be found using this class.
Python3
from datetime import datetime, timedelta
ini_time_for_now = datetime.now()
print ( "initial_date" , str (ini_time_for_now))
new_final_time = ini_time_for_now + \
`` timedelta(days = 2 )
print ( "new_final_time" , str (new_final_time))
print ( 'Time difference:' , str (new_final_time -
`` ini_time_for_now))
**Output:
initial_date 2019-10-25 12:02:32.799814
new_final_time 2019-10-27 12:02:32.799814
Time difference: 2 days, 0:00:00
Operations supported by Timedelta Class
| Operator | Description |
|---|---|
| Addition (+) | Adds and returns two timedelta objects |
| Subtraction (-) | Subtracts and returns two timedelta objects |
| Multiplication (*) | Multiplies timedelta object with float or int |
| Division (/) | Divides the timedelta object with float or int |
| Floor division (//) | Divides the timedelta object with float or int and return the int of floor value of the output |
| Modulo (%) | Divides two timedelta object and returns the remainder |
| +(timedelta) | Returns the same timedelta object |
| -(timedelta) | Returns the resultant of -1*timedelta |
| abs(timedelta) | Returns the +(timedelta) if timedelta.days > 1=0 else returns -(timedelta) |
| str(timedelta) | Returns a string in the form (+/-) day[s], HH:MM:SS.UUUUUU |
| repr(timedelta) | Returns the string representation in the form of the constructor call |
Format DateTime in Python
Formatting DateTime can be very necessary as the date representation may differ from place to place. In some countries, it can be yyyy-mm-dd and in other countries, it can be dd-mm-yyyy. To format Python Datetime strptime and strftime functions can be used.
Python Datetime strftime
A strftime() method converts the given date, time, or DateTime object to the string representation of the given format.
Python Datetime format
Python program to demonstrate strftime() function
Python3
from datetime import datetime as dt
now = dt.now()
print ( "Without formatting" , now)
s = now.strftime( "%A %m %-Y" )
print ( '\nExample 1:' , s)
s = now.strftime( "%a %-m %y" )
print ( '\nExample 2:' , s)
s = now.strftime( "%-I %p %S" )
print ( '\nExample 3:' , s)
s = now.strftime( "%H:%M:%S" )
print ( '\nExample 4:' , s)
Output
Without formatting 2021-08-19 18:16:25.881661
Example 1: Thursday 08 2021
Example 2: Thu 8 21
Example 3: 6 PM 25
Example 4: 18:16:25
**Note: For more information, refer to strftime() method.
Python DateTime strptime
The strptime() creates a DateTime object from the given string.
**Example: DateTime strptime
Python3
from datetime import datetime
time_data = [ "25/05/99 02:35:8.023" , "26/05/99 12:45:0.003" ,
`` "27/05/99 07:35:5.523" , "28/05/99 05:15:55.523" ]
format_data = "%d/%m/%y %H:%M:%S.%f"
for i in time_data:
`` print (datetime.strptime(i, format_data))
Output
1999-05-25 02:35:08.023000 1999-05-26 12:45:00.003000 1999-05-27 07:35:05.523000 1999-05-28 05:15:55.523000
Python DateTime.tzinfo()
The datetime.now() function contains no information regarding time zones. It only makes use of the current system time. Tzinfo is an abstract base class in Python. It cannot be directly instantiated. A concrete subclass must derive from this abstract class and implement the methods offered by it.
List of Python DateTime.tzinfo() Objects
| Function Name | Description |
|---|---|
| dst() | Returns tzinfo.dst() is tzinfo is not None |
| fromutc() | The purpose of this function is to adjust the date time data, returning an equivalent DateTime in self’s local time. |
| tzname() | Returns tzinfo.tzname() is tzinfo is not None |
| utcoffset() | Returns tzinfo.utcffsets() is tzinfo is not None |
**Example
The tzinfo class instance can be provided to the DateTime and time object constructors. It is used in scenarios such as converting local time to UTC or accounting for daylight savings time.
Python3
import datetime as dt
from dateutil import tz
tz_string = dt.datetime.now(dt.timezone.utc).astimezone().tzname()
print ( "datetime.now() :" , tz_string)
NYC = tz.gettz( 'Europe / Berlin' )
dt1 = dt.datetime( 2022 , 5 , 21 , 12 , 0 )
dt2 = dt.datetime( 2022 , 12 , 21 , 12 , 0 , tzinfo = NYC)
print ( "Naive Object :" , dt1.tzname())
print ( "Aware Object :" , dt2.tzname())
**Output:
datetime.now() : IST
Naive Object : None
Aware Object : None
Python DateTime timezone
Timezones in DateTime can be used in the case where one might want to display time according to the timezone of a specific region. This can be done using the pytz module of Python. This module serves the date-time conversion functionalities and helps users serving international client bases.
Python3
from datetime import datetime
from pytz import timezone
format = "%Y-%m-%d %H:%M:%S %Z%z"
now_utc = datetime.now(timezone( 'UTC' ))
print (now_utc.strftime( format ))
timezones = [ 'Asia/Kolkata' , 'Europe/Kiev' , 'America/New_York' ]
for tzone in timezones:
`` now_asia = now_utc.astimezone(timezone(tzone))
`` print (now_asia.strftime( format ))
Output
2021-08-19 18:27:28 UTC+0000 2021-08-19 23:57:28 IST+0530 2021-08-19 21:27:28 EEST+0300 2021-08-19 14:27:28 EDT-0400