如何将元组映射映射到Scala中的地图元组？

Question

有

val a: Map[String, (Int, Int)] = Map("a" -> (1, 10), "b" -> (2, 20)) 

什么是正确的斯卡拉办法从a获得

val b: (Map[String, Int], Map[String, Int]) = (Map("a" -> 1, "b" -> 2), Map("a" -> 10, "b" -> 20)) 

？

Answer 1

scala> val b = (a.mapValues(_._1), a.mapValues(_._2)) 
b: (scala.collection.immutable.Map[String,Int], scala.collection.immutable.Map[String,Int]) = (Map(a -> 1, b -> 2),Map(a -> 10, b -> 20)) 

Answer 2

import scalaz._ 
import Scalaz._ 

scala> val m = Map("a" -> (1, 10), "b" -> (2, 20)) 
m: scala.collection.immutable.Map[java.lang.String,(Int, Int)] = Map(a -> (1,10), b -> (2,20)) 

scala> val (a, b) = m.toSeq foldMap { case (k, (v1, v2)) => (Map(k -> v1), Map(k -> v2)) } 
a: scala.collection.immutable.Map[java.lang.String,Int] = Map(b -> 2, a -> 1) 
b: scala.collection.immutable.Map[java.lang.String,Int] = Map(b -> 20, a -> 10) 

Answer 3

我喜欢肖恩的答案，但如果你想要的，由于某种原因穿越地图只有一次，并没有想用Scalaz，这里是另一种解决方案：

a.foldLeft((Map.empty[String, Int], Map.empty[String, Int])) { 
    case ((a1, a2), (k, (v1, v2))) => (a1 + (k -> v1), a2 + (k -> v2)) 
}