Scala的map高阶函数应用

一 代码

1. scala> val c =List("x","y","z")
2. c:List[String]=List(x, y, z)
4. scala> c.map(x => x.toUpperCase)
5. res7:List[String]=List(X, Y, Z)
7. scala> c.map(_.toUpperCase)
8. res8:List[String]=List(X, Y, Z)
10. scala> l.filter(_%2==1)
11. res10:List[Int]=List(1,3)
13. scala> l.filter(_%2==1).map(_+10)
14. res11:List[Int]=List(11,13)
16. scala> val q=List(l,List(4,5,6))
17. q:List[List[Int]]=List(List(1,2,3),List(4,5,6))
19. scala> q.map(x=>x.filter(_%2==0))
20. res12:List[List[Int]]=List(List(2),List(4,6))
22. scala> q.map(_.filter(_%2==0))
23. res13:List[List[Int]]=List(List(2),List(4,6))
25. scala> q.flatMap(_.filter(_%2==0))
26. res15:List[Int]=List(2,4,6)