Question

Is there any way to dequeue two or more items in list comprehension.

I.e. I’d like to do something like this:

>>> q = [1, 2, 3, 4]
>>> r = [x+y for x, y in q]
** This does not work though :( **

Expected:

>>> r
[3, 7]

Answer 1

You can use the grouper recipe from the itertools documentation:

>>> from itertools import izip_longest
>>> [x + y for x, y in grouper(2,q)]
[3, 7]

The source code for the recipe is this:

def grouper(n, iterable, fillvalue=None):
    "grouper(3, 'ABCDEFG', 'x') --> ABC DEF Gxx"
    args = [iter(iterable)] * n
    return izip_longest(fillvalue=fillvalue, *args)