⍴ — Shape / Reshape⍴Y gives axis lengths.
⍴2 3⍴0 ⍝ 2x 3x
S⍴Y reshapes, cycling or truncating the ravel of Y. Dimensions are nonnegative integers. Empty Y supplies fill.
2 3⍴1 2 ⍝ 2 3⍴1 2 1 2 1 2
3⍴'' ⍝ ' '
An empty shape makes a scalar.
⍬⍴1 2 ⍝ 1