map与flatMap的区别

flatMap

val lineArray = Array("hello you","hello me","hello world")

val lines = sc.parallelize(lineArray, 1)

val words = lines.flatMap(line =>{ line.split(" ") })

words.foreach {

  word => println(word.mkString)
}

结果：

1.png

map

val lineArray = Array("hello you","hello me","hello world")

val lines = sc.parallelize(lineArray, 1)

val words = lines.map(line =>{ line.split(" ") })

words.foreach {

  word => println(word.mkString)
}

结果

1.png

map:获取一个新元素（原本几个元素还是几个元素） flatmap 获取一个或者多个新元素（比原来的元素多）