DL&NNJava 8

map与flatMap的区别

2019-02-15  本文已影响664人  一个人一匹马

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)

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