Python 3 Date and Time

Python 3 Dates and Times

Python programs can manipulate dates and times in many ways, and converting date formats is a common function.

Python provides a time and calendar modules for formatting dates and times.

Time intervals are expressed as floating-point decimals expressed in seconds.

Each timestamp is expressed as the number of seconds since midnight, January 1, 1970 (the epoch).

Python’s time module provides many functions for converting between common date formats. For example, the function time.time() is used to obtain the current timestamp, as shown in the following example:

Example

#!/usr/bin/python3<br>
<br>
import time  # Import the time module<br>
<br>
ticks = time.time()<br>
print ("Current timestamp is:", ticks)<br>

The above example outputs:

Current timestamp is: 1459996086.7115328

Timestamp units are ideal for date calculations. However, dates before 1970 cannot be represented in this way. Dates that are too far in the future also cannot be represented in this way, as UNIX and Windows only support them until 2038.

What is a time tuple?

Many Python functions use a 9-digit array to process time:

This is the struct_time tuple. This structure has the following attributes:

Getting the Current Time

To convert a floating-point timestamp to a time tuple, pass the floating-point value to a function like localtime.

#!/usr/bin/python3

import time

localtime = time.localtime(time.time())
print ("Local time is:", localtime)

The above example outputs:

Local time is: time.struct_time(tm_year=2016, tm_mon=4, tm_mday=7, tm_hour=10, tm_min=28, tm_sec=49, tm_wday=3, tm_yday=98, tm_isdst=0)

Getting a formatted time

You can choose a variety of formats depending on your needs, but the simplest function for getting a readable time format is asctime():

#!/usr/bin/python3

import time

localtime = time.asctime( time.localtime(time.time()) )
print ("Local time is:", localtime)

The above example outputs:

Local time is: Thu Apr 7 10:29:13 2016

Formatting a date

We can use the strftime method of the time module to format a date:

time.strftime(format[, t])

#!/usr/bin/python3

import time

# Format to 2016-03-20 11:45:39
print (time.strftime("%Y-%m-%d %H:%M:%S", time.localtime()))

# Format to Sat Mar 28 22:24:24 2016
print (time.strftime("%a %b %d %H:%M:%S %Y", time.localtime()))

# Convert the format string to a timestamp
a = "Sat Mar 28 22:24:24 2016"
print (time.mktime(time.strptime(a,"%a %b %d %H:%M:%S %Y")))

The above example outputs:

2016-04-07 10:29:46
Thu Apr 07 10:29:46 2016
1459175064.0

Date and time formatting symbols in Python:

• %y Two-digit year representation (00-99)
• %Y Four-digit year representation (000-9999)
• %m Month (01-12)
• %d Day of the month (0-31)
• %H 24-hour hour (0-23)
• %I Hour in 12-hour format (01-12)
• %M Minutes (00=59)
• %S Seconds (00-59)
• %a Locale’s abbreviated weekday name
• %A Locale’s full weekday name
• %b Locale’s abbreviated month name
• %B Locale’s full month name
• %c Locale’s corresponding date and time representation
• %j Day of the year (001-366)
• %p Locale’s equivalent of A.M. or P.M.
• %U Week of the year (00-53), starting on Sunday
• %w Day of the week (0-6), starting on Sunday
• %W Week number of the year (00-53), Monday as the first day of the week.
• %x Locale-specific date representation.
• %X Locale-specific time representation.
• %Z Current time zone name.
• %% The % sign itself.

Getting a Month’s Calendar.

The Calendar module has extensive methods for manipulating yearly and monthly calendars. For example, to print a calendar for a specific month:

#!/usr/bin/python3

import calendar

cal = calendar.month(2016, 1)
print ("The following prints the calendar for January 2016:")
print (cal)

The above example outputs:

The following prints the calendar for January 2016:

January 2016
Mo Tu We Th Fr Sa Su
1 2 3
4 5 6 7 8 9 10
11 12 13 14 15 16 17
18 19 20 21 22 23 24
25 26 27 28 29 30 31

---

Time Module

The Time module contains the following built-in functions, both for time processing and for converting time formats:

>>> import time
>>> print ("time.altzone %d " % time.altzone)
time.altzone -28800

>>> import time
>>> t = time.localtime()
>>> print ("time.asctime(t): %s " % time.asctime(t))
time.asctime(t): Thu Apr 7 10:36:20 2016

time.perf_counter() # Returns system uptime
time.process_time() # Returns process uptime

>>> import time
>>> print ("time.ctime() : %s" % time.ctime())
time.ctime() : Thu Apr 7 10:51:58 2016

>>> import time
>>> print ("localtime(): ", time.localtime(1455508609.34375))
localtime(): time.struct_time(tm_year=2016, tm_mon=2, tm_mday=15, tm_hour=11, tm_min=56, tm_sec=49, tm_wday=0, tm_yday=46, tm_isdst=0)

#!/usr/bin/python3
import time

print ("Start : %s" % time.ctime())
time.sleep( 5 )
print ("End : %s" % time.ctime())

>>> import time
>>> print (time.strftime("%Y-%m-%d %H:%M:%S", time.localtime()))
2016-04-07 11:18:05

>>> import time
>>> struct_time = time.strptime("30 Nov 00", "%d %b %y")
>>> print ("Return tuple: ", struct_time)
Return tuple: time.struct_time(tm_year=2000, tm_mon=11, tm_mday=30, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=3, tm_yday=335, tm_isdst=-1)

>>> import time
>>> print(time.time())
1459999336.1963577

The Time module contains the following two important properties:

Calendar Module

This module contains functions related to the calendar, such as printing a text calendar for a particular month.

Monday is the default first day of the week, and Sunday is the default last day. To change this setting, call calendar.setfirstweekday(). The module includes the following built-in functions:

>>> import calendar
>>> print(calendar.isleap(2000))
True
>>> print(calendar.isleap(1900))
False

>>> import calendar
>>> calendar.monthrange(2014, 11)
(5, 30)

Other related modules and functions

Other modules for handling dates and times in Python include:

• time module
• datetime module