Splitting string into groups

Question

I\'m trying to \'group\' a string into segments, I guess this example would explain it more succintly

scala> val str: String = \"aaaabbcddeeeeeeffg\"
...          


        

Answer 1

Edit: Have to read more carefully. Below is no functional code.

Sometimes, a little mutable state helps:

def group(s : String) = {
  var tmp = ""
  val b = Seq.newBuilder[String]

  s.foreach { c =>
    if ( tmp != "" && tmp.head != c ) {
      b += tmp
      tmp = ""
    }

    tmp += c
  }
  b += tmp

  b.result
}

Runtime O(n) (if segments have at most constant length) and tmp.+= probably creates the most overhead. Use a string builder instead for strict runtime in O(n).

group("aaaabbcddeeeeeeffg")
> Seq[String] = List(aaaa, bb, c, dd, eeeeee, ff, g)