# get a field

Tim Chase python.list at tim.thechases.com
Mon Feb 15 19:28:25 CET 2010

  Holden wrote:
> mierdatutis mi wrote:
>> I have this:
>>
>> pe="http://www.rtve.es/mediateca/videos/20100211/saber-comer---patatas-castellanas-costillas-11-02-10/691046.shtml"
>>
>> I would like to extract this: 691046.shtml
>>
>> But is dynamically. Not always have the same lenght the string.
>
>>>> s = "http://server/path/to/file/file.shtml"
>>>> s.rfind("/")         # finds rightmost "/"
> 26
>>>> s[s.rfind("/")+1:]   # substring starting after "/"
> 'file.shtml'

If I didn't use os.path.basename(s) then I'd write this as
"s.rsplit('/', 1)[-1]"

>>> "http://server/path/to/file/file.shtml".rsplit('/', 1)[-1]
'file.shtml'
>>> "".rsplit('/', 1)[-1]
''
>>> "file.html".rsplit('/', 1)[-1]
'file.html'

I don't know how much of a difference it makes, but I always
appreciate seeing how various people solve the same problem.  I
tend to lean away from the find()/index() methods on strings
because I have to stop and think which one raises the exception
and which one returns -1 (and that it's -1 instead of 0) usually
dropping to a python shell and doing

>>> help("".find)
>>> help("".index)

to refresh my memory.

FWIW, Steve's solution and the os.path.basename() both produce
the same results with all 3 input values, so it's more a matter
of personal style preference.  The basename() version has
slightly different results if you have Windows paths with
backslashes:

s = r'c:\path\to\file.txt'

but since you (OP) know that they should be URLs with
forward-slashes, it should be a non-issue.

-tkc