RosettaCodeData/Task/Entropy/Icon/entropy.icon

procedure main(a)
    s := !a | "1223334444"
    write(H(s))
end

procedure H(s)
    P := table(0.0)
    every P[!s] +:= 1.0/*s
    every (h := 0.0) -:= P[c := key(P)] * log(P[c],2)
    return h
end