Question

我有这样的Map：

val map: Map[String, Any] = Map(
  "Item Version" -> 1.0,
  "Item Creation Time" -> "2019-04-14 14:15:09",
  "Trade Dictionary" -> Map(
    "Country" -> "India",
    "TradeNumber" -> "1",
    "action" -> Map(
      "Action1" -> false
    ),
    "Value" -> "XXXXXXXXXXXXXXX"
  ),
  "Payments" -> Map(
    "Payment Details" -> List(
      Map(
        "Payment Date" -> "2019-04-11",
        "Payment Type" -> "Rej"
))))

我写了一段代码：

def flattenMap(map: Map[String, Any]): Map[String, Any] = {
  val c = map.flatten {
    case ((key, map : Map[String, Any])) => map
    case ((key, value)) => Map(key -> value)
    // case ((key, List(map))) =>
  }.toMap
  return c
}

def secondFlatten(map: Map[String, Any]): Map[String, Any] = {
  val c=map.flatten {
    case ((key, map : Map[String, Any])) => flattenMap(map)
    case ((key, value)) => Map(key -> value)
  }.toMap

  return c 
}

哪个给出这样的输出：

(Country, India)
(Action1, false)
(Value, XXXXXXXXXXXXXXX)
(Item Version, 1.0)
(TradeNumber, 1)
(Item Creation Time, 2019-04-14 14:15:09)
(Payment Details, List(Map(Payment Date -> 2019-04-11, Payment Type -> Rej)))

我想进行一些代码更改，在其中我可以将地图列表转换为类似于输出的地图，即应该代替(Payment Details,List(Map(Payment Date -> 2019-04-11, Payment Type -> Rej)))，我应该得到：

(Payment Date , 2019-04-11), 
(Payment Type , Rej)

Answer 1

对于您的特定情况，您可以更新flattenMap方法：

def flattenMap(map: Map[String, Any]): Map[String, Any] = {
  val c = map.flatten {
    case ((key, map : Map[String, Any])) => map
    case ((key, value)) => Map(key -> value)
    case ((key, map :: Nil)) => map
  }.toMap
  return c
}

如果要处理多个地图的列表，则可能应该将返回的值包装到列表中，因此请使用某种flatMap而不是toMap。

Answer 2

您应该处理地图列表。根据您提供的示例，我已将您的方法更新为：

def secondFlatten(map: Map[String, Any]):Map[String, Any]={
 map.flatten {
   case ((key, map : Map[String, Any])) => {
     map.flatten {
       case ((key: String, l: List[Map[String, Any]])) => l.head
       case ((key: String, m : Map[String, Any])) => m
       case (key: String, value: String) => Map(key -> value)
     }
   }
   case ((key, value)) => Map(key -> value)
 }.toMap
}

这可能对您在评论中提出的问题很有用。它将所有键附加在一起，并在地图中保留价值。如果您需要更复杂的解决方案，可以进一步扩展它：

  def secondFlatten(map: Map[String, Any]):Map[String, Any]={
   map.flatten {
     case ((key, map : Map[String, Any])) => {
       map.flatten {
         case ((innerKey: String, l: List[Map[String, Any]])) => l.head.map{case (x:String, y: Any)=> (s"$key--$innerKey--$x"-> y)}
         case ((innerKey: String, m : Map[String, Any])) => m.map{case (x:String, y: Any)=> (s"$key--$innerKey--$x"-> y)}
         case (innerKey: String, value: String) => Map(s"$key--$innerKey"-> value)
    }
  }
  case ((key, value)) => Map(key -> value)
}.toMap

}

如何在Scala中将地图列表转换为地图？

2 个答案: