Spark算子:map和flatMap區別
- 2020 年 3 月 29 日
- 筆記
flatMap=map + flatten
例1:
scala> val test=List("hello java","hello python","hello hadoop") test: List[String] = List(hello java, hello python, hello hadoop)
map輸出結果:
scala> test.map(line=>line).foreach(x=>println(x)) hello java hello python hello hadoop
flatMap輸出結果1:
scala> test.flatMap(line=>line.split(" ")).foreach(x=>println(x)) hello java hello python hello hadoop
flatMap輸出結果2:
scala> text.flatMap(line=>line).foreach(x=>println(x)) h e l l o j a v a h ……