Question

What is the proper way to compare 2 times in Python in order to speed test a section of code? I tried reading the API docs. I’m not sure I understand the timedelta thing.

So far I have this code:

from datetime import datetime  tstart = datetime.now() print t1  # code to speed test  tend = datetime.now() print t2 # what am I missing? # I'd like to print the time diff here 

Answer 1

datetime.timedelta is just the difference between two datetimes … so it’s like a period of time, in days / seconds / microseconds

>>> import datetime >>> a = datetime.datetime.now() >>> b = datetime.datetime.now() >>> c = b - a  >>> c datetime.timedelta(0, 4, 316543) >>> c.days 0 >>> c.seconds 4 >>> c.microseconds 316543 

Be aware that c.microseconds only returns the microseconds portion of the timedelta! For timing purposes always use c.total_seconds().

You can do all sorts of maths with datetime.timedelta, eg:

>>> c / 10 datetime.timedelta(0, 0, 431654) 

It might be more useful to look at CPU time instead of wallclock time though … that’s operating system dependant though … under Unix-like systems, check out the ‘time’ command.