如何按值对 scala.collection.Map[java.lang.String, Int] 进行排序？
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how to sort a scala.collection.Map[java.lang.String, Int] by its values?
提问by Jan Willem Tulp
How would you sort a scala.collection.Map[java.lang.String, Int] by its values (so on the Int)? What is a short and elegant way to do that?
你将如何通过它的值（在 Int 上）对 scala.collection.Map[java.lang.String, Int] 进行排序？什么是一种简短而优雅的方式来做到这一点？
回答by mkneissl
Depending on what the expected output collection type is (SortedMaps are sorted on the keys), you could use something like this:
根据预期的输出集合类型（SortedMaps 按键排序），您可以使用以下内容：
Map("foo"->3, "raise"->1, "the"->2, "bar"->4).toList sortBy {_._2}
Result would be the list of key/value pairs sorted by the value:
结果将是按值排序的键/值对列表：
List[(java.lang.String, Int)] = List((raise,1), (the,2), (foo,3), (bar,4))
There is a Map type that retains the original order, ListMap, if you apply this, you have a map again:
有一个 Map 类型保留了原来的顺序ListMap，如果你应用这个，你又得到了一个地图：
import collection.immutable.ListMap
ListMap(Map("foo"->3, "raise"->1, "the"->2, "bar"->4).toList.sortBy{_._2}:_*)
Then you have:
那么你有：
scala.collection.immutable.ListMap[java.lang.String,Int] = Map((raise,1), (the,2), (foo,3), (bar,4))
(Scala 2.8)
（斯卡拉 2.8）
