How to do a reduceByKey in Julia

New to Julia
7

Here is the Queryverse way of doing it:

rand('a':'f',100) |> 
  @groupby(_) |>
  @map({char=key(_), count=length(_)}) |>
  @vlplot(:bar, x="count", y="char:n")

It is not entirely clear though whether this starts with the kind of data structure you were asking for? Here we start with a Vector{Char}, not a Vector{String}, which you were asking about?