Scala - 展平包含Seq的Seq

Question

鉴于:

Seq(1,2,3) map {
  case 1 => 11
  case 2 => Seq(12,13,14)
  case 3 => 15
}

我怎样才能优雅地将其展平为Seq[Int]含有Seq(11,12,13,14,15)？

Answer 1

这是一种方法:

Seq(1,2,3) flatMap {
  case 1 => Seq(11)
  case 2 => Seq(12,13,14)
  case 3 => Seq(15)
}

res0:Seq [Int] = List(11,12,13,14,15)