Most pythonic way to extend a list to exactly a certain length? [duplicate]

Answer 1

How about islice-ing the concatenation of the original list with a padding generator?

from itertools import islice, repeat
def fit_to_size(l, n):
    return list(islice(
        ( x
          for itr in (l, repeat(0))
          for x in itr ),
        n))

You might prefer this slightly more explicit implementation:

def fit_to_size(l, n):
    def gen():
        yield from l
        while True: yield 0
    return list(islice(gen(), n))