scala - Spark/Scala : Expand a list of (List[String], 字符串)元组

Question

基本上this question仅适用于 Scala。

给定具有表单元素的 RDD，我如何进行以下转换

(List[String], String) => (String, String)

例如

([A,B,C], X)
([C,D,E], Y)

to

(A, X)
(B, X)
(C, X)
(C, Y)
(D, Y)
(E, Y)

所以

Answer 1

scala> val l = List((List('a, 'b, 'c) -> 'x), List('c, 'd, 'e) -> 'y)
l: List[(List[Symbol], Symbol)] = List((List('a, 'b, 'c),'x),
                                       (List('c, 'd, 'e),'y))

scala> l.flatMap { case (innerList, c) => innerList.map(_ -> c) }
res0: List[(Symbol, Symbol)] = List(('a,'x), ('b,'x), ('c,'x), ('c,'y),
                                    ('d,'y), ('e,'y))