Date and Time Math in Python

It is very easy to do date and time maths in Python using timedelta objects. Whenever you want to add or subtract to a date/time, use a datetime.datetime(), then add or subtract datetime.timedelta() instances. A timedelta object represents a duration, the difference between two dates or times. The timedelta constructor has the following function signature −

datetime.timedelta([days[, seconds[, microseconds[, milliseconds[, minutes[, hours[, weeks]]]]]]])

Note: All arguments are optional and default to 0. Arguments may be ints, longs, or floats, and may be positive or negative. You can read more about it here − https://docs.python.org/2/library/datetime.html#timedelta-objects

Example

An example of using the timedelta objects and dates −

import datetime
old_time = datetime.datetime.now()
print(old_time)
new_time = old_time - datetime.timedelta(hours=2, minutes=10)
print(new_time)

Output

This will give the output −

2018-01-04 11:09:00.694602
2018-01-04 08:59:00.694602

timedelta() arithmetic is not supported for datetime.time() objects; if you need to use offsets from an existing datetime.time() object, just use datetime.datetime.combine() to form a datetime.datetime() instance, do your calculations, and 'extract' the time again with the .time() method.

Subtracting 2 datetime objects gives a timedelta object. This timedelta object can be used to find the exact difference between the 2 datetimes.

Example

t1 = datetime.datetime.now()
t2 = datetime.datetime.now()
print(t1 - t2)
print(type(t1 - t2))

Output

This will give the output −

-1 day, 23:59:56.653627
<class 'datetime.timedelta'>