scala - 如何将输入数据转换为以下格式？ - 通过...分组

Question

我所拥有的是我正在编写的一段 scala 代码中函数的以下输入数据:

List(
  (1,SubScriptionState(CNN,ONLINE,Seq(12))), 
  (1,SubScriptionState(SKY,ONLINE,Seq(12))), 
  (1,SubScriptionState(FOX,ONLINE,Seq(12))), 
  (2,SubScriptionState(CNN,ONLINE,Seq(12))), 
  (2,SubScriptionState(SKY,ONLINE,Seq(12))), 
  (2,SubScriptionState(FOX,ONLINE,Seq(12))), 
  (2,SubScriptionState(CNN,OFFLINE,Seq(13))), 
  (2,SubScriptionState(SKY,ONLINE,Seq(13))), 
  (2,SubScriptionState(FOX,ONLINE,Seq(13))), 
  (3,SubScriptionState(CNN,OFFLINE,Seq(13))), 
  (3,SubScriptionState(SKY,ONLINE,Seq(13))), 
  (3,SubScriptionState(FOX,ONLINE,Seq(13)))
)

SubscriptionState 在这里只是一个案例类:

case class SubscriptionState(channel: Channel, state: ChannelState, subIds: Seq[Long])

我想把它改成这样:

Map(
  1 -> Map(
        SubScriptionState(SKY,ONLINE,Seq(12)) -> 1, 
        SubScriptionState(CNN,ONLINE,Seq(12)) -> 1, 
        SubScriptionState(FOX,ONLINE,Seq(12)) -> 1),

  2 -> Map(
        SubScriptionState(SKY,ONLINE,Seq(12,13)) -> 2, 
        SubScriptionState(CNN,ONLINE,Seq(12)) -> 1, 
        SubScriptionState(FOX,ONLINE,Seq(12,13)) -> 2, 
        SubScriptionState(CNN,OFFLINE,Seq(13)) -> 1),  

  3 -> Map(
        SubScriptionState(SKY,ONLINE,Seq(13)) -> 1, 
        SubScriptionState(FOX,ONLINE,Seq(13)) -> 1, 
        SubScriptionState(CNN,OFFLINE,Seq(13)) -> 1)
)

我将如何在 scala 中执行此操作？

Answer 1

这是我解决问题的方法。我认为这可能不是一个完美的解决方案，但它会如您所愿地工作。

  val result: Map[Int, Map[SubscriptionState, Int]] = list
    .groupBy(_._1)
    .view
    .mapValues { statesById =>
      statesById
        .groupBy { case (_, subscriptionState) => (subscriptionState.channel, subscriptionState.state) }
        .map { case (_, groupedStatesById) =>
          val subscriptionState = groupedStatesById.head._2 // groupedStatesById should contain at least one element
          val allSubIds = groupedStatesById.flatMap(_._2.subIds)
          val updatedSubscriptionState = subscriptionState.copy(subIds = allSubIds)
          updatedSubscriptionState -> allSubIds.size
        }
    }.toMap