[Python-ideas] Add 'interleave' function to itertools?

[MRAB]

On 07/08/2013 20:19, Vito De Tullio wrote:
> MRAB wrote:
>
>> def interleave(*iterables):
>>      """Return a interleave object whose .__next__() method returns an
>>      element from each iterable argument in turn.  The .__next__()
>>      method continues until the shortest iterable in the argument
>>      sequence is exhausted and then it raises StopIteration.
>>      """
>>
>>      sources = [iter(iterable) for iterable in iterables]
>>
>>      try:
>>          while True:
>>              for iterable in sources:
>>                  yield next(iterable)
>>      except StopIteration:
>>          pass
>
> isn't something like
>
>      def interleave(*iterables):
>          for zipped_iterables in zip(*iterables):
>             yield from zipped_iterables
>
> sufficient?
>
> (and the same for interleave_longest / zip_longest)
>
You're probably correct, although there's still the corner case of what
should happen when an iterable is exhausted. For example, what should
list(interleave([0, 2, 4], [1, 3])) return? Should it be [0, 1, 2, 3,
4] or [0, 1, 2, 3]? In other words, if there are 'n' iterables, should
'interleave' always yield a multiple of 'n' items? Should there be a
function for each case?

And are these functions worthy of inclusion in itertools? :-)