Scala Map [（String，String），Int]建立对应的MAP [String，String]

Question

How to transform:

(Map(UserLang -> en, UserName -> a),1)
(Map(UserLang -> jp, UserName -> b),1)

to

 (UserLang -> en, UserName -> a)
 (UserLang -> jp, UserName -> b)

How to do this via functional programming

Answer 1

Try something like this:

val map1: Map[(String, String),Int]
val map2: Map[String, String] = map1.keySet.toMap

.keySet discards the Int and turns your Map[(String, String),Int] into a Set[(String,String)] which you can then easily convert to a Map by calling toMap .

Answer 2

(Map(UserLang -> en, UserName -> a),1) is type (Map[String,String], Int) and not Map[(String,String),Int] as stated in the question title.

For the former, try map(_._1) . For the latter try keys.toMap .