datetime

Python has the datetime module to help deal with timestamps in your code. Time values are represented with the time class. Times have attributes for hour, minute, second, and microsecond. They can also include time zone information. The arguments to initialize a time instance are optional, but the default of 0 is unlikely to be what you want.

time

Lets take a look at how we can extract time information from the datetime module. We can create a time-stamp by specifying datetime.time(hour,minute,second,microsecond)



In [3]:

    
import datetime

t = datetime.time(4, 20, 1)
# Lets show the different compoenets

print t
print 'hour  :', t.hour
print 'minute:', t.minute
print 'second:', t.second
print 'microsecond:', t.microsecond
print 'tzinfo:', t.tzinfo









    



04:20:01
hour  : 4
minute: 20
second: 1
microsecond: 0
tzinfo: None

Note: A time instance only holds values of time, and not a date associated with the time.

We can also check the min and max values a time of day can have in the module:



In [5]:

    
print 'Earliest  :', datetime.time.min
print 'Latest    :', datetime.time.max
print 'Resolution:', datetime.time.resolution









    



Earliest  : 00:00:00
Latest    : 23:59:59.999999
Resolution: 0:00:00.000001

The min and max class attributes reflect the valid range of times in a single day.

Dates

datetime (as you might suspect) also allows us to work with date timestamps. Calendar date values are represented with the date class. Instances have attributes for year, month, and day. It is easy to create a date representing today’s date using the today() class method.

Lets see some examples:



In [6]:

    
today = datetime.date.today()
print today
print 'ctime:', today.ctime()
print 'tuple:', today.timetuple()
print 'ordinal:', today.toordinal()
print 'Year:', today.year
print 'Mon :', today.month
print 'Day :', today.day









    



2015-09-18
ctime: Fri Sep 18 00:00:00 2015
tuple: time.struct_time(tm_year=2015, tm_mon=9, tm_mday=18, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=4, tm_yday=261, tm_isdst=-1)
ordinal: 735859
Year: 2015
Mon : 9
Day : 18

As with time, the range of date values supported can be determined using the min and max attributes.



In [7]:

    
print 'Earliest  :', datetime.date.min
print 'Latest    :', datetime.date.max
print 'Resolution:', datetime.date.resolution









    



Earliest  : 0001-01-01
Latest    : 9999-12-31
Resolution: 1 day, 0:00:00

Another way to create new date instances uses the replace() method of an existing date. For example, you can change the year, leaving the day and month alone.



In [8]:

    
d1 = datetime.date(2015, 3, 11)
print 'd1:', d1

d2 = d1.replace(year=1990)
print 'd2:', d2









    



d1: 2015-03-11
d2: 1990-03-11

Arithmetic

We can perform arithmetic on date objects to check for time differences. For example:



In [9]:

    
d1









    Out[9]:





datetime.date(2015, 3, 11)



In [10]:

    
d2









    Out[10]:





datetime.date(1990, 3, 11)



In [11]:

    
d1-d2









    Out[11]:





datetime.timedelta(9131)

This give us the difference in days between the two dates. You can use the timedelta method to specify various units of times (day,minutes,hours,etc...)

Great! You should now have a basic understanding of how to use datetime with Python to work with timestamps in your code!