x IBM AAPL GOOG GOOG AAPL MSFT IBM AAPL AAPL IBM
≢ x 10 ≢ 3.14159 1 ≢⍯ x ⍝ {⍬⍴⍴⍵}⍯ x; group count 3 4 2 1 {(+⌿⍵)÷≢⍵} 3 1 4 1 5 9 3.83333