Question

我如何通过他们的键以短的方式合并两个地图，但他们可以有不同的键。例如，我有

val query1 = Map(("email", "aa@ya.ru"), ("phone", "ph0997832"))
val query2 = Map(("email", "bb@ya.ru"), ("fax", "fax0997832"))

我想要那样的东西：

List("email", "phone", "fax")
List(List("aa@ya.ru", "ph0997832", ""), List("bb@ya.ru", "", "fax0997832"))

Answer 1

使用：

scala> val queries = List(query1, query2)
queries: List[Map[String,String]] = List(
                                      Map(email -> aa@ya.ru, phone -> ph0997832),
                                      Map(email -> bb@ya.ru, fax -> fax0997832)
                                    )

获得钥匙很容易;在.keys上调用Map，展平结果并删除重复项：

scala> val keys = queries.flatMap(_.keys).distinct
keys: List[String] = List(email, phone, fax)

获取第二个清单;获取查询的所有键的值，使用.getOrElse(k, "")获取空字符串而不是None：

scala> queries.map(q => keys.map(k => q.getOrElse(k, "")))
res0: List[List[String]] = List(List(aa@ya.ru, ph0997832, ""),
                                List(bb@ya.ru, "", fax0997832))

按键合并不同的Map

1 个答案: