Calculating time in Python output format

Question

In this thread we have a good solution How to calculate the time interval between two time strings

But how I can edit the output format? From H:MM:SS to HH:MM, like 00:40 instead of 0:40:00

from datetime import datetime
from datetime import timedelta

T1 = input()
T2 = input()
format = '%H:%M'
tdiff = datetime.strptime(T1, format) - datetime.strptime(T2, format)

if tdiff.days < 0:
    tdiff = timedelta(days = 0,
                seconds = tdiff.seconds, microseconds = tdiff.microseconds)

print(tdiff)

EDIT: Thank you. This code below quite works, but the only problem is 7:45 instead of 07:45 for example. The code below removes the problem of seconds at the end. Now I only don't know how to force 0 is front of <10 hours format.

from datetime import datetime
from datetime import timedelta

T1 = input()
T2 = input()
format = '%H:%M'
tdiff = datetime.strptime(T1, format) - datetime.strptime(T2, format)

if tdiff.days < 0:
    tdiff = timedelta(days = 0,
                seconds = tdiff.seconds, microseconds = tdiff.microseconds)

print(str(tdiff).rstrip("0").rstrip(":"))

Answer 1

You're contradicting yourself by saying from H:MM:SS to HH:MM but you give an example of where you remove hours not seconds. Anyway, I'm guessing what you mean is that you want to remove any leading zeroes if they're empty (remove hours)?

In that case, there's two options. Either build the string yourself like so:

from datetime import datetime
from datetime import timedelta

T1 = '00:50'
T2 = '00:40'
format = '%H:%M'
tdiff = datetime.strptime(T1, format) - datetime.strptime(T2, format)

if tdiff.days < 0:
    tdiff = timedelta(days = 0, seconds = tdiff.seconds, microseconds = tdiff.microseconds)

print(':'.join([block for block in str(tdiff).split(':') if block != '0']))

Where you skip single-digit zeroes (hours) but leave double-digit zeroes (seconds etc) intact.

Or you could do:

print(str(tdiff).lstrip("0").lstrip(":"))

Which simply strips the beginning. replace with .rstrip() if you need to strip the end.

And if you want to make sure there's always a two-digit representation in the first example, you could do:

print(':'.join(['{:02}'.format(int(block)) for block in str(tdiff).split(':') if block != '0']))

At this point, you're monkey-patching a problem that most likely could be solved in a neater and more efficient way, and your original problem description is not really in line with what you're asking/trying to fix. But this is one way of doing it.

If you want to remove seconds but keep hours intact, do something like:

print(':'.join(['{:02}'.format(int(block)) for block in str(tdiff).split(':')[:-1]]))