Slice/Group a sequence of equal chars in F#

Question

I need to extract the sequence of equal chars in a text.

For example: The string \"aaaBbbcccccccDaBBBzcc11211\" should be converted to a list of strings

Answer 1

How about with groupby

"aaaBbbcccccccD"
|> Seq.groupBy id
|> Seq.map (snd >> Seq.toArray)
|> Seq.map (fun t -> new string (t))

If you input order matters, here is a method that works

"aaaBbbcccccccDaBBBzcc11211"
|> Seq.pairwise
|> Seq.toArray
|> Array.rev
|> Array.fold (fun (accum::tail) (ca,cb) -> if ca=cb then System.String.Concat(accum,string ca)::tail else string(ca)::accum::tail)   (""::[])