Some built-in to pad a list in python

Question

I have a list of size < N and I want to pad it up to the size N with a value.

Certainly, I can use something like the following, but I feel that there should be something I missed:

>>> N = 5
>>> a = [1]
>>> map(lambda x, y: y if x is None else x, a, ['']*N)
[1, '', '', '', '']

Answer 1

If you want to pad with None instead of '', map() does the job:

>>> map(None,[1,2,3],xrange(7))

[(1, 0), (2, 1), (3, 2), (None, 3), (None, 4), (None, 5), (None, 6)]

>>> zip(*map(None,[1,2,3],xrange(7)))[0]

(1, 2, 3, None, None, None, None)

Answer 2

To go off of kennytm:

def pad(l, size, padding):
    return l + [padding] * abs((len(l)-size))

>>> l = [1,2,3]
>>> pad(l, 7, 0)
[1, 2, 3, 0, 0, 0, 0]