Migration level must be such that ⎕ML<1 (otherwise ∊ means Enlist. See Enlist).

Y may be any array.  R is an array with the same shape and structure as Y in which a numeric value is replaced by 0 and a character value is replaced by ' '.

Examples

      ∊(2 3⍴⍳6)(1 4⍴'TEXT')
 0 0 0
 0 0 0
 
      ' '=∊'X'
1