Question

Sometimes I get a string like “02:40” indicating 2 hours and 40 minutes. I’d like to parse that string into the number of minutes (160 in this case) using Python.

Sure, I can parse the string and multiply the hours by 60, but is there something in the standard lib that does this?

Answer 1

Personally, I think simply parsing the string is far easier to read:

>>> s = '02:40'
>>> int(s[:-3]) * 60 + int(s[-2:])
160

Note that using negative indexing means it will handle strings without the leading zero on the hour:

>>> s = '2:40'
>>> int(s[:-3]) * 60 + int(s[-2:])
160

You could also use the split() function:

>>> hours, minutes = s.split(':')
>>> int(hours) * 60 + int(minutes)
160

Or use the map() function to convert the pieces to integers:

>>> hours, minutes = map(int, s.split(':'))
>>> hours * 60 + minutes
160

Speed

Using the timeit module indicates it is also faster than other methods proposed here:

>>> import timeit
>>> parsetime = timeit.timeit("mins = int(s[:-3]) * 60 + int(s[-2:])", "s='02:40'", number=100000) / 100000
>>> parsetime
9.018449783325196e-06

The split() method is a bit slower:

>>> splittime = timeit.timeit("hours,minutes = s.split(':'); mins=int(hours)*60 + int(minutes)", "s='02:40'", number=100000)/100000
>>> splittime
1.1217889785766602e-05
>>> splittime/parsetime
1.2438822697120402

And using map() a bit slower again:

>>> splitmaptime = timeit.timeit("hours,minutes = map(int, s.split(':')); mins=hours*60 + minutes", "s='02:40'", number=100000)/100000
>>> splitmaptime
1.3971350193023682e-05
>>> splitmaptime/parsetime
1.5491964282881776

John Machin’s map and sum is about 2.4 times slower:

>>> summaptime = timeit.timeit('mins=sum(map(lambda x, y: x * y, map(int, "2:40".split(":")), [60, 1]))', "s='02:40'", number=100000) / 100000
>>> summaptime
2.1276121139526366e-05
>>> summaptime/parsetime
2.43

Chrono Kitsune’s strptime()-based answer is ten times slower:

>>> strp = timeit.timeit("t=time.strptime(s, '%H:%M');mins=t.tm_hour * 60 + t.tm_min", "import time; s='02:40'", number=100000)/100000
>>> strp
9.0362770557403569e-05
>>> strp/parsetime
10.019767557444432