A gnarly little python loop

Steve Howell showell30 at yahoo.com
Sun Nov 11 18:29:15 CET 2012


On Nov 11, 1:09 am, Paul Rubin <no.em... at nospam.invalid> wrote:
> Cameron Simpson <c... at zip.com.au> writes:
> > | I'd prefer the original code ten times over this inaccessible beast.
> > Me too.
>
> Me, I like the itertools version better.  There's one chunk of data
> that goes through a succession of transforms each of which
> is very straightforward.

Thanks, Paul.

Even though I supplied the "inaccessible" itertools version, I can
understand why folks find it inaccessible.  As I said to the OP, there
was nothing wrong with the original imperative approach; I was simply
providing an alternative.

It took me a while to appreciate itertools, but the metaphor that
resonates with me is a Unix pipeline.  It's just a metaphor, so folks
shouldn't be too literal, but the idea here is this:

  page_nums -> pages -> valid_pages -> tweets

The transforms are this:

  page_nums -> pages: call API via imap
  pages -> valid_pages: take while true
  valid_pages -> tweets: use chain.from_iterable to flatten results

Here's the code again for context:

    def get_tweets(term):
        def get_page(page):
            return getSearch(term, page)
        page_nums = itertools.count(1)
        pages = itertools.imap(get_page, page_nums)
        valid_pages = itertools.takewhile(bool, pages)
        tweets = itertools.chain.from_iterable(valid_pages)
        return tweets



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