减少在Scala中映射[Key，List[Value]]的元组序列的可变数量

我有两个序列：

Seq("a" -> 1, "b" -> 2)
Seq("a" -> 3, "b" -> 4)

我想要的是一个如下所示的结果图：

Map(a -> List(3, 1), b -> List(4, 2))

您可以对其进行排序，也可以对其进行排序。

您可以尝试

scala> val seq = Seq("a" -> 1, "b" -> 2) ++ Seq("a" -> 3, "b" -> 4)
seq: Seq[(String, Int)] = List((a,1), (b,2), (a,3), (b,4))

scala> seq groupBy(_._1) mapValues(_ map(_._2))
res9: scala.collection.immutable.Map[String,Seq[Int]] = Map(b -> List(2, 4), a -> List(1, 3))

val s1 = Seq("a" -> 1, "b" -> 2)
val s2 = Seq("a" -> 3, "b" -> 4)

val ss = s1 ++ s2

val toMap = ss.groupBy(x => x._1).map { case (k,v) => (k,  v.map(_._2))}

res0: scala.collection.immutable.Map[String,Seq[Int]] = Map(b -> List(2, 4), a -> List(1, 3))

scala> val seq = Seq("a" -> 1, "b" -> 2) ++ Seq("a" -> 3, "b" -> 4)
seq: Seq[(String, Int)] = List((a,1), (b,2), (a,3), (b,4))

scala> seq groupBy(_._1) mapValues(_ map(_._2))
res9: scala.collection.immutable.Map[String,Seq[Int]] = Map(b -> List(2, 4), a -> List(1, 3))