Split a Seq[A] into (Seq[B], Seq[C]) so can retrieve multiple Seq's while just looping over the Seq just once.

SeqWithSplitOn.scala

  /**
    * Extend [[Seq]] with a function to seperate an element into multiple parts.
    * This allows to go over the [[Seq]] only once and retrieve multiple [[Seq]]s as a result.
    * Convenient for changing a Seq of [[Tuple2]] into 2 Seq's of the tuple elements.
    */
  implicit class SeqWithSplitOn[A](val seq: Seq[A]) extends AnyVal {
    /**
      * Split an element into 2 parts using function `f`.
      * Note: simply use the [[identity()]] function for splitting a [[Tuple2]] element.
      *
      * @param f Function to apply to each element.
      * @tparam B Type of first part.
      * @tparam C Type of second part.
      * @return Two sequences of B's and C's.
      */
    def splitElement[B,C](f: A => (B, C)): (Seq[B], Seq[C]) = {
      seq.foldLeft((Seq.empty[B], Seq.empty[C])) {
        case ((seqB, seqC), elem) =>
          val (b, c) = f(elem) // seperate the element into 2 parts
          (seqB :+ b, seqC :+ c)
      }
    }
  }