slicing list of lists in Python

Question

I need to slice a list of lists in python.

A = [[1,2,3,4,5],[1,2,3,4,5],[1,2,3,4,5]]
idx = slice(0,4)
B = A[:][idx]

The code above isn\'t

Answer 1

Either:

>>> [a[slice(0,3)] for a in A]
[[1, 2, 3], [1, 2, 3], [1, 2, 3]]

Or:

>>> [list(filter(lambda x: x<=3, a)) for a in A]
[[1, 2, 3], [1, 2, 3], [1, 2, 3]]