//Group elements by key, convert the iterable to list, then sort them in descending order, take the first 200 element
//Sort the result RDD by key
val sortedRdd = calcChiSquares.groupByKey().map{case(k,v) => (k ,
                                                              v.toList.sortWith(_.split(":")(1).toDouble > _.split(":")(1).toDouble)
                                                              .take(200).mkString(" "))}.sortByKey()