Scala groupBy列表

Question

我想创建一个映射,其中键是字符串,值是字符串在列表中出现的次数.我尝试了这种groupBy方法,但一直没有成功.

Answer 1

必填答案

scala> val l = List("abc","abc","cbe","cab")
l: List[String] = List(abc, abc, cbe, cab)

scala> l.groupBy(identity).mapValues(_.size) 
res91: scala.collection.immutable.Map[String,Int] = Map(cab -> 1, abc -> 2, cbe -> 1)