[Python-ideas] Possible new itertool: comm()

Paul Moore p.f.moore at gmail.com
Tue Jan 6 17:44:04 CET 2015

On 6 January 2015 at 16:33, Ian Cordasco <graffatcolmingov at gmail.com> wrote:
> So my question is how well with this work with generators/iterators?
> Your examples use lists, but it would be impossible to use this with
> anything that isn't finite right?

The examples use lists because I was using doctest and needed
checkable output. But I think it should work fine with any (finite)
iterator. I don't see a problem with the algorithm if I use infinite
iterators (the algorithm is one-pass and generates results on demand)
but I haven't tested it explicitly.

[pause, test...]

Yep, looks OK:

    >>> import itertools
    >>> c1 = itertools.count()
    >>> c2 = itertools.count(3)
    >>> output = comm(c1, c2)
    >>> next(output)
    ('<', 0)
    >>> next(output)
    ('<', 1)
    >>> next(output)
    ('<', 2)
    >>> next(output)
    ('=', 3)


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