Shape and Reshape

Reshape

Z←L⍴R returns an array of shape L whose items are taken from R in row major order, repeated as necessary.

L is a scalar or vector of non-negative integers, and R is an arbitrary array.

If the right argument is empty, the result consists of ×/⍴L copies of the fill item of R.

For example, in origin-1

      2 3⍴⍳6
 1 2 3
 4 5 6
      2 3⍴⍳0
 0 0 0
 0 0 0

The idea for the latter enhancement was taken from Dyalog APL.

Rho

The symbol ⍴ used with no left argument returns the size or dimensions of a scalar, string, vector, array or matrix.