In python how can I set multiple values of a list to zero simultaneously?

Question

Conceptually, I want to do:

arr[20:] = 0

where arr is a list. How can I do this?

Answer 1

You can do it directly using slice assignment.

arr[20:] = [0] * (len(arr) - 20)

But the natural way is just to iterate.

for i in xrange(20, len(arr)):
    arr[i] = 0