access 2d list python 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: two dimensional array python

# Creates a list containing 5 lists, each of 8 items, all set to 0
w, h = 8, 5;
Matrix = [[0 for y in range(h)] for x in range(w)] 

Matrix[0][0] = 1
Matrix[0][6] = 3 # error! range... 
Matrix[6][0] = 3 # valid