Splitting a string

Patrick Maupin pmaupin at gmail.com
Sat Apr 3 00:53:07 CEST 2010


On Apr 2, 4:32 pm, Peter Otten <__pete... at web.de> wrote:

> _split = re.compile(r"(\d+)").split
> def split(s):
>     if not s:
>         return ()
>     parts = _split(s)
>     parts[1::2] = map(int, parts[1::2])
>     if parts[-1] == "":
>         del parts[-1]
>     if parts[0] == "":
>         del parts[0]
>     return tuple(parts)
>

That's certainly faster than a list comprehension (at least on long
lists), but it might be a little obscure why the "if not s:" is
needed, so unless Thomas has a really long result list, he might want
to just keep the list comprehension, which is (IMO) very readable.

Alternatively, this is halfway between the previous example and the
list comprehension:

_split = re.compile(r"(\d+)").split
def split(s):
    parts = _split(s)
    parts[1::2] = map(int, parts[1::2])
    for index in (-1, 0):
        if parts and parts[index] == "":
            del parts[index]
    return tuple(parts)

BTW, I just remembered that, although I have often used the fact that
split returns alternating non-match/match/.../match/non-match in the
past, the last time I did this particular task (of splitting out
digits from a string), I didn't make use of that fact.  But I wasn't
expecting very many splits for this case.  FWIW, here's a class I
wrote that does this to a string for the express purpose of making
sorts work better:

http://code.google.com/p/pyeda/source/browse/trunk/kipy/kipy/utility/istring.py

Regards,
Pat



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