如何将多个case类的RDD转换为其组件的RDD

case class Person(name: String, age: Int)
case class Address(city: String, country: String)

val personsRDD = sparkContext.parallelize(Seq(
  Person("John", 25),
  Person("Alice", 30),
  Person("Bob", 35)
))

val addressesRDD = sparkContext.parallelize(Seq(
  Address("New York", "USA"),
  Address("London", "UK"),
  Address("Sydney", "Australia")
))

val namesRDD = personsRDD.map(_.name)
val agesRDD = personsRDD.map(_.age)

val citiesRDD = addressesRDD.map(_.city)
val countriesRDD = addressesRDD.map(_.country)