[Python-ideas] Include partitioning in itertools

[David Mertz]

This doesn't make sense to me for `itertools`.  There is no way to
"partition" an infinite sequence in the style of the recipe you show (nor
any sensible one I can think of).  I think a better name would be
`powerset()` anyway; but in either case, it's not an `itertools` type of
operation.

I think what might be more useful is to make a mix-in class that gave
concrete collections a `.powerset()` method that preserved the types of the
original collection.  I think you can even do this as an iterable without
having to concretize the whole set of subsets (but not from an iterable,
from a concrete collection, as input).

On Sun, Nov 1, 2015 at 3:08 AM, Albert ten Oever <agtoever at hotmail.com>
wrote:

> Hi all,
>
> I really hope this isn't proposed before - I couldn't find anything in the
> archives.
>
> I want to propose to include a 'partition' (mathematically more correct: a
> set partition) function in itertools. To my knowledge, partitioning of a
> set (iterable) is quite a common thing to do and a logic extension of the
> combinatoric generators in itertools.
>
> It is implemented as a Python recipe (
> http://code.activestate.com/recipes/576795-partitioning-a-sequence/). I
> found that implementing a partition generator of an iterable isn't very
> straightforward, which, in my opinion, strengthens the case for
> implementing it as a separate function.
>
> Definitions of partitions: http://mathworld.wolfram.com/SetPartition.html
> or https://en.wikipedia.org/wiki/Partition_of_a_set
>
> Humble regards,
>
> Albert.
>
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