Y may be any array. The axis specification is optional. If present, K must be a simple integer scalar or one-element vector. The value of K must be an axis of Y. If absent, the last axis is implied.
The items of R are the sub-arrays of Y along the Kth axis. R is a scalar if Y is a scalar. Otherwise R is an array whose rank is ¯1+⍴⍴Y and whose shape is (K≠⍳⍴⍴Y)/⍴Y.
↓3 4⍴'MINDTHATSTEP' MIND THAT STEP ↓2 5⍴⍳10 1 2 3 4 5 6 7 8 9 10 ↓[1]2 5⍴⍳10 1 6 2 7 3 8 4 9 5 10