Given the python code below, please help me understand what is happening there.
start_time = time.time()
time.sleep(42)
end_time = time.time()
uptime = end_time - start_time
human_uptime = str(datetime.timedelta(seconds=int(uptime)))
So I get the difference between start time and end time, on line 5 I round up the duration by casting and what now, what's the further explanation?
I know what delta means(average or difference), but why do I have to pass seconds = uptime to timedelta and why does the string casting works so nicely that I get HH:MM:SS ?
Answer
Because timedelta is defined like:
class datetime.timedelta([days,] [seconds,] [microseconds,] [milliseconds,] [minutes,] [hours,] [weeks])
All arguments are optional and default to 0.
You can easily say "Three days and four milliseconds" with optional arguments that way.
>>> datetime.timedelta(days=3, milliseconds=4)
datetime.timedelta(3, 0, 4000)
>>> datetime.timedelta(3, 0, 0, 4) #no need for that.
datetime.timedelta(3, 0, 4000)
And for str casting, it returns a nice formatted value instead of __repr__ to improve readability. From docs:
str(t) Returns a string in the form [D day[s], ][H]H:MM:SS[.UUUUUU], where D is negative for negative t. (5)
>>> datetime.timedelta(seconds = 42).__repr__()
'datetime.timedelta(0, 42)'
>>> datetime.timedelta(seconds = 42).__str__()
'0:00:42'
Checkout documentation:
http://docs.python.org/library/datetime.html#timedelta-objects