[Python-ideas] Batching/grouping function for itertools

[Steven D'Aprano]

On Sun, Dec 08, 2013 at 09:13:06AM -0600, Ron Adam wrote:

> Possibly function to take the next n items of an iterator without advancing 
> it.

Fundamentally impossible. The best you can do it advance the iterator 
but store the results for later use.


> Along with a function to advance an iterator n ahead without taking 
> anything.

Too trivial to bother with. Just advance the iterator and throw the 
result away.

def advance(it, n):
    for _ in range(n):
        next(it)

You can even do it as a one-linear, at the expense of readability:

{next(it) and None for _ in range(n)}.pop()

(The pop isn't really necessary, I just like the fact that it means the 
expression evaluates as None.)


> These would be simpler and easier to maintain, and have a wider range of 
> uses.

Maybe, maybe not, but they don't solve the problem that people keep 
asking to be solved.



-- 
Steven