Python Datetime
A date in Python is not a data type of its own, but we can import a module named datetime
to work with dates as date objects.
Example
Import the datetime module and display the current date:
import datetime
x = datetime.datetime.now[]
print[x]
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Date Output
When we execute the code from the example above the result will be:
The date contains year, month, day, hour, minute, second, and microsecond.
The datetime
module has many methods to return information about the date object.
Here are a few examples, you will learn more about them later in this chapter:
Example
Return the year and name of weekday:
import datetime
x = datetime.datetime.now[]
print[x.year]
print[x.strftime["%A"]]
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Creating Date Objects
To create a date, we can use the datetime[]
class [constructor] of the datetime
module.
The datetime[]
class requires three parameters to create a date: year, month, day.
Example
Create a date object:
import datetime
x = datetime.datetime[2020, 5, 17]
print[x]
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The datetime[]
class also takes parameters for time and timezone [hour, minute, second, microsecond, tzone], but they are optional, and has a default value of 0
, [None
for timezone].
The strftime[] Method
The datetime
object has a method for formatting date objects into readable strings.
The method is called
strftime[]
, and takes one parameter, format
, to specify the format of the returned string:
Example
Display the name of the month:
import datetime
x = datetime.datetime[2018, 6, 1]
print[x.strftime["%B"]]
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A reference of all the legal format codes:
%a | Weekday, short version | Wed | Try it » |
%A | Weekday, full version | Wednesday | Try it » |
%w | Weekday as a number 0-6, 0 is Sunday | 3 | Try it » |
%d | Day of month 01-31 | 31 | Try it » |
%b | Month name, short version | Dec | Try it » |
%B | Month name, full version | December | Try it » |
%m | Month as a number 01-12 | 12 | Try it » |
%y | Year, short version, without century | 18 | Try it » |
%Y | Year, full version | 2018 | Try it » |
%H | Hour 00-23 | 17 | Try it » |
%I | Hour 00-12 | 05 | Try it » |
%p | AM/PM | PM | Try it » |
%M | Minute 00-59 | 41 | Try it » |
%S | Second 00-59 | 08 | Try it » |
%f | Microsecond 000000-999999 | 548513 | Try it » |
%z | UTC offset | +0100 | |
%Z | Timezone | CST | |
%j | Day number of year 001-366 | 365 | Try it » |
%U | Week number of year, Sunday as the first day of week, 00-53 | 52 | Try it » |
%W | Week number of year, Monday as the first day of week, 00-53 | 52 | Try it » |
%c | Local version of date and time | Mon Dec 31 17:41:00 2018 | Try it » |
%C | Century | 20 | Try it » |
%x | Local version of date | 12/31/18 | Try it » |
%X | Local version of time | 17:41:00 | Try it » |
%% | A % character | % | Try it » |
%G | ISO 8601 year | 2018 | Try it » |
%u | ISO 8601 weekday [1-7] | 1 | Try it » |
%V | ISO 8601 weeknumber [01-53] | 01 | Try it » |
Python has a module named datetime to work with dates and times. Let's create a few simple programs related to date and time before we dig deeper.
Example 1: Get Current Date and Time
import datetime
datetime_object = datetime.datetime.now[]
print[datetime_object]
When you run the program, the output will be something like:
2018-12-19 09:26:03.478039
Here, we have imported datetime module using import datetime
statement.
One of
the classes defined in the datetime
module is datetime
class. We then used now[]
method to create a datetime
object containing the current local date and time.
Example 2: Get Current Date
import datetime
date_object = datetime.date.today[]
print[date_object]
When you run the program, the output will be something like:
2018-12-19
In this program, we have used today[]
method defined in the date
class to get a date
object containing the current local date.
What's inside datetime?
We can use dir[] function to get a list containing all attributes of a module.
import datetime
print[dir[datetime]]
When you run the program, the output will be:
['MAXYEAR', 'MINYEAR', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__spec__', '_divide_and_round', 'date', 'datetime', 'datetime_CAPI', 'time', 'timedelta', 'timezone', 'tzinfo']
Commonly used classes in the datetime module are:
- date Class
- time Class
- datetime Class
- timedelta Class
datetime.date Class
You can instantiate date
objects from the
date
class. A date object represents a date [year, month and day].
Example 3: Date object to represent a date
import datetime
d = datetime.date[2019, 4, 13]
print[d]
When you run the program, the output will be:
2019-04-13
If you are wondering, date[]
in the above example is a constructor of the date
class. The constructor takes three arguments: year, month and day.
The variable a is a date
object.
We can only import
date
class from the datetime
module. Here's how:
from datetime import date
a = date[2019, 4, 13]
print[a]
Example 4: Get current date
You can create a date
object containing the current date by using a classmethod named today[]
. Here's how:
from datetime import date
today = date.today[]
print["Current date =", today]
Example 5: Get date from a timestamp
We can also create date
objects from a timestamp. A Unix timestamp is the number of seconds between a particular date and January 1, 1970 at UTC.
You can convert a timestamp to date using fromtimestamp[]
method.
from datetime import date
timestamp = date.fromtimestamp[1326244364]
print["Date =", timestamp]
When you run the program, the output will be:
Date = 2012-01-11
Example 6: Print today's year, month and day
We can get year, month, day, day of the week etc. from the date object easily. Here's how:
from datetime import date
# date object of today's date
today = date.today[]
print["Current year:", today.year]
print["Current month:", today.month]
print["Current day:", today.day]
datetime.time
A time object instantiated from the time
class represents the local time.
Example 7: Time object to represent time
from datetime import time
# time[hour = 0, minute = 0, second = 0]
a = time[]
print["a =", a]
# time[hour, minute and second]
b = time[11, 34, 56]
print["b =", b]
# time[hour, minute and second]
c = time[hour = 11, minute = 34, second = 56]
print["c =", c]
# time[hour, minute, second, microsecond]
d = time[11, 34, 56, 234566]
print["d =", d]
When you run the program, the output will be:
a = 00:00:00 b = 11:34:56 c = 11:34:56 d = 11:34:56.234566
Example 8: Print hour, minute, second and microsecond
Once you create a time
object, you can easily print its attributes such as hour, minute etc.
from datetime import time
a = time[11, 34, 56]
print["hour =", a.hour]
print["minute =", a.minute]
print["second =", a.second]
print["microsecond =", a.microsecond]
When you run the example, the output will be:
hour = 11 minute = 34 second = 56 microsecond = 0
Notice that we
haven't passed microsecond argument. Hence, its default value 0
is printed.
datetime.datetime
The datetime
module has a class named dateclass
that can contain information from both date and time objects.
Example 9: Python datetime object
from datetime import datetime
#datetime[year, month, day]
a = datetime[2018, 11, 28]
print[a]
# datetime[year, month, day, hour, minute, second, microsecond]
b = datetime[2017, 11, 28, 23, 55, 59, 342380]
print[b]
When you run the program, the output will be:
2018-11-28 00:00:00 2017-11-28 23:55:59.342380
The
first three arguments year, month and day in the datetime[]
constructor are mandatory.
Example 10: Print year, month, hour, minute and timestamp
from datetime import datetime
a = datetime[2017, 11, 28, 23, 55, 59, 342380]
print["year =", a.year]
print["month =", a.month]
print["hour =", a.hour]
print["minute =", a.minute]
print["timestamp =", a.timestamp[]]
When you run the program, the output will be:
year = 2017 month = 11 day = 28 hour = 23 minute = 55 timestamp = 1511913359.34238
datetime.timedelta
A timedelta
object represents the difference between two dates or times.
Example 11: Difference between two dates and times
from datetime import datetime, date
t1 = date[year = 2018, month = 7, day = 12]
t2 = date[year = 2017, month = 12, day = 23]
t3 = t1 - t2
print["t3 =", t3]
t4 = datetime[year = 2018, month = 7, day = 12, hour = 7, minute = 9, second = 33]
t5 = datetime[year = 2019, month = 6, day = 10, hour = 5, minute = 55, second = 13]
t6 = t4 - t5
print["t6 =", t6]
print["type of t3 =", type[t3]]
print["type of t6 =", type[t6]]
When you run the program, the output will be:
t3 = 201 days, 0:00:00 t6 = -333 days, 1:14:20 type of t3 = type of t6 =
Notice, both t3 and t6 are of type.
Example 12: Difference between two timedelta objects
from datetime import timedelta
t1 = timedelta[weeks = 2, days = 5, hours = 1, seconds = 33]
t2 = timedelta[days = 4, hours = 11, minutes = 4, seconds = 54]
t3 = t1 - t2
print["t3 =", t3]
When you run the program, the output will be:
t3 = 14 days, 13:55:39
Here, we have created two
timedelta
objects t1 and t2, and their difference is printed on the screen.
Example 13: Printing negative timedelta object
from datetime import timedelta
t1 = timedelta[seconds = 33]
t2 = timedelta[seconds = 54]
t3 = t1 - t2
print["t3 =", t3]
print["t3 =", abs[t3]]
When you run the program, the output will be:
t3 = -1 day, 23:59:39 t3 = 0:00:21
Example 14: Time duration in seconds
You can get the total number of seconds in a timedelta object using total_seconds[]
method.
from datetime import timedelta
t = timedelta[days = 5, hours = 1, seconds = 33, microseconds = 233423]
print["total seconds =", t.total_seconds[]]
When you run the program, the output will be:
total seconds = 435633.233423
You can also find sum of two dates and times
using +
operator. Also, you can multiply and divide a timedelta
object by integers and floats.
Python format datetime
The way date and time is represented may be different in different places, organizations etc. It's more common to use mm/dd/yyyy
in the US, whereas dd/mm/yyyy
is more common in the UK.
Python has strftime[]
and strptime[]
methods to handle this.
Python strftime[] - datetime object to string
The strftime[]
method is defined under classes date
, datetime
and time
. The method creates a formatted string from a given date
, datetime
or time
object.
Example 15: Format date using strftime[]
from datetime import datetime
# current date and time
now = datetime.now[]
t = now.strftime["%H:%M:%S"]
print["time:", t]
s1 = now.strftime["%m/%d/%Y, %H:%M:%S"]
# mm/dd/YY H:M:S format
print["s1:", s1]
s2 = now.strftime["%d/%m/%Y, %H:%M:%S"]
# dd/mm/YY H:M:S format
print["s2:", s2]
When you run the program, the output will be something like:
time: 04:34:52 s1: 12/26/2018, 04:34:52 s2: 26/12/2018, 04:34:52
Here, %Y
, %m
, %d
, %H
etc. are format codes. The strftime[]
method takes one or more format codes and returns a formatted
string based on it.
In the above program, t, s1 and s2 are strings.
%Y
- year [0001,..., 2018, 2019,..., 9999]%m
- month [01, 02, ..., 11, 12]%d
- day [01, 02, ..., 30, 31]%H
- hour [00, 01, ..., 22, 23%M
- minute [00, 01, ..., 58, 59]%S
- second [00, 01, ..., 58, 59]
To learn more about strftime[]
and format codes, visit:
Python strftime[].
Python strptime[] - string to datetime
The strptime[]
method creates a datetime
object from a given string [representing date and time].
Example 16: strptime[]
from datetime import datetime
date_string = "21 June, 2018"
print["date_string =", date_string]
date_object = datetime.strptime[date_string, "%d %B, %Y"]
print["date_object =", date_object]
When you run the program, the output will be:
date_string = 21 June, 2018 date_object = 2018-06-21 00:00:00
The strptime[]
method takes two arguments:
- a string representing date and time
- format code equivalent to the first argument
By the way, %d
, %B
and %Y
format codes are used for day, month[full name] and year respectively.
Visit Python strptime[] to learn more.
Handling timezone in Python
Suppose, you are working on a project and need to display date and time based on their timezone. Rather than trying to handle timezone yourself, we suggest you to use a third-party pytZ module.
from datetime import datetime
import pytz
local = datetime.now[]
print["Local:", local.strftime["%m/%d/%Y, %H:%M:%S"]]
tz_NY = pytz.timezone['America/New_York']
datetime_NY = datetime.now[tz_NY]
print["NY:", datetime_NY.strftime["%m/%d/%Y, %H:%M:%S"]]
tz_London = pytz.timezone['Europe/London']
datetime_London = datetime.now[tz_London]
print["London:", datetime_London.strftime["%m/%d/%Y, %H:%M:%S"]]
When you run the program, the output will be something like:
Local time: 2018-12-20 13:10:44.260462 America/New_York time: 2018-12-20 13:10:44.260462 Europe/London time: 2018-12-20 13:10:44.260462
Here, datetime_NY and datetime_London are datetime objects containing the current date and time of their respective timezone.