Unique Mask R←≠Y

Y may be any array.

R is a Boolean vector whose length is the number of major cells in Y. For each major cell of Y, the corresponding element of R is 1 if it is the first occurrence of that value, and 0 if it is a duplicate of an earlier major cell.

⎕CT and ⎕DCT are implicit arguments of Unique.

Examples

      ≠22 10 22 22 21 10 5 10
1 1 0 0 1 0 1 0

      ≠ v←'CAT' 'DOG' 'CAT' 'DUCK' 'DOG' 'DUCK'
1 1 0 1 0 0

      ⊢mat←↑v 
CAT 
DOG 
CAT 
DUCK
DOG 
DUCK
      ≠mat
1 1 0 1 0 0