scala之flatMap函数

格式

def flatMap[B, That](f: Int => scala.collection.GenTraversableOnce[B])(implicit bf: scala.collection.generic.CanBuildFrom[Array[Int],B,That]): That
def flatMap[B, That](f: Int => scala.collection.GenTraversableOnce[B])(implicit bf: scala.collection.generic.CanBuildFrom[scala.collection.mutable.WrappedArray[Int],B,That]): That

数据

scala> val a = Array(3,5,1,7,2,9,4)

scala> a.flatMap(x=>1 to x)
res25: Array[Int] = Array(1, 2, 3, 1, 2, 3, 4, 5, 1, 1, 2, 3, 4, 5, 6, 7, 1, 2, 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 2, 3, 4)

数据

scala> val a=Array(3,3,3)

scala> a.flatMap(x=>1 to x)
res27: Array[Int] = Array(1, 2, 3, 1, 2, 3, 1, 2, 3)