Good use for itertools.dropwhile and itertools.takewhile

[Neil Cerutti]

On 2012-12-04, Nick Mellor <thebalancepro at gmail.com> wrote:
> I have a file full of things like this:
>
> "CAPSICUM RED fresh from Queensland"
>
> Product names (all caps, at start of string) and descriptions
> (mixed case, to end of string) all muddled up in the same
> field. And I need to split them into two fields. Note that if
> the text had said:
>
> "CAPSICUM RED fresh from QLD"
>
> I would want QLD in the description, not shunted forwards and
> put in the product name. So (uncontrived) list comprehensions
> and regex's are out.
>
> I want to split the above into:
>
> ("CAPSICUM RED", "fresh from QLD")
>
> Enter dropwhile and takewhile. 6 lines later:
>
> from itertools import takewhile, dropwhile
> def split_product_itertools(s):
>     words = s.split()
>     allcaps = lambda word: word == word.upper()
>     product, description = takewhile(allcaps, words), dropwhile(allcaps, words)
>     return " ".join(product), " ".join(description)
>
> When I tried to refactor this code to use while or for loops, I
> couldn't find any way that felt shorter or more pythonic:

I'm really tempted to import re, and that means takewhile and
dropwhile need to stay. ;)

But seriously, this is a quick implementation of my first thought.

description = s.lstrip(string.ascii_uppercase + ' ')
product = s[:-len(description)-1]

-- 
Neil Cerutti