One value is assigned to all my lists components

Question

In order to reduce the quantity of code (and also lazyness) I did this in python thinking that it would make me write less than [[0,0],[0,0]....]

a = [[0,0]]*10

However when I was assigning something like a[0][:] = [1,2], then all of my values became into [1,2] (like [[1,2]]*10)

I have checked and if I do the whole [[0,0],[0,0]....] I could solve the problem, but that's not good. Could anyone help me?

`[[0,0] for _ in range(10)]` works. But this is a duplicate of many other questions — RemcoGerlich, Dec 20 '16 at 13:38

score -1 · Answer 1 · edited Dec 20 '16 at 13:42

-1

I solved it with Numpy.

a = np.array([[0, 0]] * 10)

edited Dec 20 '16 at 13:42

Elmar Peise

answered Dec 20 '16 at 13:37

There's more to this question; the problem is that creating nested lists like this only copies a reference to the inner list, so if you mutate one element, you mutate all of them. – Andras Deak -- Слава Україні Dec 20 '16 at 13:38

1 Answers1