How do I get an empty list of any size in Python?

If by "array" you actually mean a Python list, you can use

a = [0] * 10

or

a = [None] * 10

You can't do exactly what you want in Python (if I read you correctly). You need to put values in for each element of the list (or as you called it, array).

But, try this:

a = [0 for x in range(N)]  # N = size of list you want
a[i] = 5  # as long as i < N, you're okay

For lists of other types, use something besides 0. None is often a good choice as well.