You can also do zip(arr[::3], arr[1::3], arr[2::3]) which is nearly as fast but doesn't work with iterators. If you want to use iterators you could also d

You can also do zip(arr[::3], arr[1::3], arr[2::3]) which is nearly as fast but doesn't work with iterators. If you want to use iterators you could also do zip(islice(arr, 0, None, 3), islice(arr, 1, None, 3), islice(arr, 2, None, 3)) which is a tad slower.