Creating lists of lists in a pythonic way

Question

I\'m using a list of lists to store a matrix in python. I tried to initialise a 2x3 Zero matrix as follows.

mat=[[0]*2]*3

However, when I chang

Answer 1

Is there anything itertools can't do? :)

>>> from itertools import repeat,izip
>>> rows=3
>>> cols=6
>>> A=map(list,izip(*[repeat(0,rows*cols)]*cols))
>>> A
[[0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0]]
>>> A[0][3] = 2
>>> A
[[0, 0, 0, 2, 0, 0], [0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0]]