How to decide if an string is in hh:mm format in python?
Question
I'd like to know if there is a function which returns True if a string is in "hh:mm" hour format? I can write my own function, but it would be good if there is a standard function.
Best Regards
Solution
Just try to interpret it using the time
module, and catch the ValueError
raised when the conversion fails:
>>> time.strptime('08:30', '%H:%M')
time.struct_time(tm_year=1900, tm_mon=1, tm_mday=1, tm_hour=8, tm_min=30, tm_sec=0, tm_wday=0, tm_yday=1, tm_isdst=-1)
>>> time.strptime('08:70', '%H:%M')
Traceback (most recent call last):
(...)
ValueError: unconverted data remains: 0
>>> time.strptime('0830', '%H:%M')
Traceback (most recent call last):
(...)
ValueError: time data '0830' does not match format '%H:%M'
The only thing this doesn't check is that you actually specify the correct number of digits. Checking if len(time_string) == 5
might be simple enough to check that.
Edit: inspired by Kimvais in the comments; to wrap it as a function:
def is_hh_mm_time(time_string):
try:
time.strptime(time_string, '%H:%M')
except ValueError:
return False
return len(time_string) == 5
OTHER TIPS
You can use time.strptime
:
>>> help(time.strptime)
Help on built-in function strptime in module time:
strptime(...)
strptime(string, format) -> struct_time
Parse a string to a time tuple according to a format specification.
See the library reference manual for formatting codes (same as strftime()).
To parse a time string that works:
>>> time.strptime('12:32', '%H:%M')
time.struct_time(tm_year=1900, tm_mon=1, tm_mday=1, tm_hour=12, tm_min=32, tm_sec=0, tm_wday=0, tm_yday=1, tm_isdst=-1)
If you pass in a time string that is not valid, you will get an error:
>>> time.strptime('32:32', '%H:%M')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "C:\Python27\lib\_strptime.py", line 454, in _strptime_time
return _strptime(data_string, format)[0]
File "C:\Python27\lib\_strptime.py", line 325, in _strptime
(data_string, format))
ValueError: time data '32:32' does not match format '%H:%M'
So... your function could look like this:
def is_hh_mm(t):
try:
time.strptime(t, '%H:%M')
except:
return False
else:
return True
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