python 2d list indexing code example

Example 1: how to create 2d list in python

o=[]
for i in range(0,rows):
    x=[]
    for j in range(0,cols):
        x.append(0)
    o.append(x)
#if you use [[0]*cols]*rows all rows will become the same list
#so editing in one row will edit all rows

Example 2: python print 2d array as table

for row in A:
    for val in row:
        print '{:4}'.format(val),
    print