Cookbooks
Python
Chapter 7. Dates and Times
Calculating a date in the future or past

Python:
Calculating a date in the future or past

How to:

Python’s datetime module makes working with dates and times a breeze. Check this out:

from datetime import datetime, timedelta

# Current date and time
now = datetime.now()
print("Now: ", now)

# Adding 10 days 
future_date = now + timedelta(days=10)
print("Future date (+10 days): ", future_date)

# Subtracting 5 days
past_date = now - timedelta(days=5)
print("Past date (-5 days): ", past_date)

Output could look like:

Now: 2023-04-01 12:34:56.789012
Future date (+10 days): 2023-04-11 12:34:56.789012
Past date (-5 days): 2023-03-27 12:34:56.789012

Simple, right? Just tweak the days, or use weeks, hours, minutes, or seconds in timedelta to jump to the time you need.

Deep Dive

Way back when, calculating dates and times was a pain. You’d deal with leap years, time zones, daylight saving - a mess. With Python’s datetime and its companions date and time, it’s smooth sailing. The module handles the complications behind the scenes.

You might ask about alternatives. Sure thing. Libraries like dateutil can handle more complex date manipulations and parsing. It’s a go-to when datetime isn’t quite cutting it.

Implementation-wise, when you use timedelta, Python adjusts the date taking into account leap years and such. Always check your results though - especially when dealing with time zones. And remember, datetime is naive by default; it doesn’t consider time zones unless you tell it to.

See Also

Comparing two dates