Any help?

Question

I found this bit of code in a challenge:

x=[[0]*2]*2
x[0][0]=1

I don't understand why x becomes [[1,0],[1,0]]
instead of [[1,0][0,0]]

Answer 1

[0]*2 creates the list [0, 0]. So [[0]*2]*2 creates [[0, 0], [0, 0]], but each of the [0, 0]s is the *same list* (I'll call that list l, so x = [l, l]). x[0][0] modifies the first element of that list (l) to 1, so now l is [1, 0], so x is [[1, 0], [1, 0]].

Answer 2

Do you mean where both [1, 1]s are the same list? If so, then

x = [[1]*2]*2

would do it directly. If you want to change them to [1, 1] from [1, 0],

x[0][1] = 1

changes x to [[1, 1][1, 1]].

Answer 3

Got it, thanks a lot :)
Is there any way to produce [[1,1],[1,1]] in the same fashion?

Answer 4

Okay thank you