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

Use a list comprehension:

>>> mat = [[0]*2 for x in xrange(3)]
>>> mat[0][0] = 1
>>> mat
[[1, 0], [0, 0], [0, 0]]

Or, as a function:

def matrix(rows, cols):
    return [[0]*cols for x in xrange(rows)]