Since you're looking at alternatives... you might as well include: zip( arr[0::3], arr[1::3], arr[2::3] ) It's pretty fast, especially if the array is pre-alloc

Since you're looking at alternatives... you might as well include: zip( arr[0::3], arr[1::3], arr[2::3] ) It's pretty fast, especially if the array is pre-allocated rather than a generated iterator.