Hints on 10 (roll)
kshitijsachan opened this issue · comments
I'm not sure how to solve roll. I think I should make a permutation matrix, but I don't know how to make the full permutation matrix in one line? Would appreciate a hint.
There are two ways to do this. One is to create a permutation matrix as you say. The other is to use advanced indexing, and just use the fact that arr[ind_arr] will work even if ind_arr is a tensor.
Ah advanced indexing, of course! Thanks :)