⍷ Find

Find searches for instances of the left argument within the right argument. A boolean result is returned with a 1 where the start of the left argument is found in the right argument. The shape of the result is the same as the shape of the right argument.

             'ME'⍷'HOME AGAIN'       (Find the pattern 'ME' in 'HOME AGAIN')
       0 0 1 0 0 0 0 0 0 0
             WEEK
       SUNDAY
       MONDAY
       TUESDAY
       WEDNESDAY
       THURSDAY
       FRIDAY
       SATURDAY
             'DAY' ⍷ WEEK            (Find the pattern 'DAY' in WEEK)
       0 0 0 1 0 0 0 0 0
       0 0 0 1 0 0 0 0 0
       0 0 0 0 1 0 0 0 0
       0 0 0 0 0 0 1 0 0
       0 0 0 0 0 1 0 0 0
       0 0 0 1 0 0 0 0 0
       0 0 0 0 0 1 0 0 0
             WEEK ⍷ 'DAY'            (WEEK not found in 'DAY' - wrong rank)
       0 0 0

The arguments can be of any rank, but ⍷ always searches for the whole of the left argument in the right argument.

             (1 2) (3 4) ⍷ 'START' (1 2 3) (1 2) (3 4)
       0 0 1 0                       (Search within nested vector)
             MAT
        1  2  3  4  5
        6  7  8  9 10
       11 12 13 14 15
       16 17 18 19 20
             (2 2⍴7 8 12 13)⍷MAT     (Search pattern is a matrix)
       0 0 0 0 0                     (1 shows top left corner)
       0 1 0 0 0
       0 0 0 0 0
       0 0 0 0 0

See also the system function ⎕SS for string search operations on vectors.