Remove the microsecond precision from a datetime in Python

Call datetime.replace(microsecond=0).

If you print the current date as an ISO timestamp in Python, by default it includes microsecond precision (in this case, .499258):

>>> d = datetime.now()
>>> d.isoformat()
'2025-10-19T09:23:04.384593'

I wanted to print some timestamps which are just HH:MM:SS, without the microseconds.

I could define a custom printer, or Python will also do what I want if I set the microseconds to zero:

>>> d.replace(microsecond=0).isoformat()
'2025-10-19T09:23:04'

I don’t love the decision to say “don’t print the microseconds if it’s zero”, because there is a difference between “microseconds is unknown” and “microseconds is known to be zero” – but in practice, that’s a subtle distinction, and anybody who really cares in that level of detail is probably using strftime() to more precisely control their output.