Simple python code about double loop

Question

I tested the following python code on Spyder IDE. Thinking it would output 2d array q as increasing number as 0..31 from q[0][0] to q[3][7]

Answer 1

As explained the problem is caused due to * operation on lists, which create more references to the same object. What you should do is to use append:

q=[]
for i in range(4): 
    q.append([])
    for j in range(8): 
        q[i].append(8*i+j)
print q 

[[0, 1, 2, 3, 4, 5, 6, 7], [8, 9, 10, 11, 12, 13, 14, 15], [16, 17, 18, 19, 20, 21, 22, 23], [24, 25, 26, 27, 28, 29, 30, 31]]