Map can not be serializable in scala?

Question

I am new to Scala. How come the \"map\" function is not serializable? How to make it serializable? For example, if my code is like below:

val data = sc.paral         


        

Answer 1

Have you tried running this same code in an application? I suspect this is an issue with the spark shell. If you want to make it work in the spark shell then you might try wrapping the definition of myfunc and its application in curly braces like so:

val data = sc.parallelize(List(1,4,3,5,2,3,5))

val result = { 
  def myfunc(iter: Iterator[Int]) : Iterator[Int] = {
    val lst = List(("a", 1),("b", 2),("c",3), ("a",2))
    var res = List[Int]()
    while (iter.hasNext) {
      val cur = iter.next
      val a = lst.groupBy(x => x._1).mapValues(_.size)
      val b= a.map(x => x._2)
      res = res ::: List(cur)
    }
    res.iterator
  }
  data.mapPartitions(myfunc).collect
}