itertools comments [Was: Re: RELEASED: Python 2.3a2]

[Christian Tanzer]

"Raymond Hettinger" <python at rcn.com> wrote:

> > def xgroup(iter,n=2):
> >     r"""Iterate `n`-wise (default pairwise)  over `iter`.
>
> Sounds interesting enough to put on the list of ideas being
> entertained.  Also, it is consistent with the idea of "iterator
> algebra".
>
> For the time being, my goal is to start with a small set of
> tools that have proven useful in Haskell and SML.  Over
> time, other candidates will considered.
>
> This one would have a much better chance if some common
> use cases could be shown and if it can be demonstrated that
> it is a useful building block in combination with the other
> itertools.

I happen to use this function. Greping over my source tree for
`pairwise` shows 46 uses in 1074 files (disclaimer: that is
a usage frequency of only 0.00017 <wink>).

Typical usage (blatantly made up):

    def test_sort(some_list) :
        sorted_list = myq_sort(some_list)
        for l, r in pairwise(sorted_list) :
            assert l <= r

I never needed anything like `triplewise`, though.

-- 
Christian Tanzer                                         tanzer at swing.co.at
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