scala - 如何访问和更新 map map 的可变 map 中的值

Question

我有一个三级数据结构(缩进和换行以提高可读性):

scala> import scala.collection.mutable.Map
import scala.collection.mutable.Map

scala> val m = Map("normal" -> Map("home" -> Map("wins" -> 0, "scores" -> 0),
                                   "away" -> Map("wins" -> 0, "scores" -> 0)))
m: scala.collection.mutable.Map[java.lang.String,
   scala.collection.mutable.Map[java.lang.String,
   scala.collection.mutable.Map[java.lang.String,Int]]] = 
Map((normal,Map(away -> Map(wins -> 0, scores -> 0),
     home -> Map(wins -> 0, scores -> 0))))

访问最里面的数据(分数)需要大量输入:

import org.scalatest.{Assertions, FunSuite}

class MapExamplesSO extends FunSuite with Assertions {
  test("Update values in a mutable map of map of maps") {
    import scala.collection.mutable.Map
    // The m map is essentially an accumulator
    val m = Map("normal" -> 
                Map("home" -> Map("wins" -> 0, "scores" -> 0),
                    "away" -> Map("wins" -> 0, "scores" -> 0)
                  )
          )
    //
    // Is there a less verbose way to increment the scores ?
    //
    assert(m("normal").apply("home").apply("scores") === 0)

    val s1 = m("normal").apply("home").apply("scores") + 1
    m("normal").apply("home").update("scores", s1)

    assert(m("normal").apply("home").apply("scores") === 1)

    val s2 = m("normal").apply("home").apply("scores") + 2
    m("normal").apply("home").update("scores", s2)

    assert(m("normal").apply("home").apply("scores") === 3)
  }
}

有没有更简洁的方法来修改分数的值？

我是 Scala 新手，因此也欢迎对上述代码的所有其他观察。

Answer 1

您不必使用“应用”，只需使用“()”正常进行即可

m("normal")("home")("scores") = 1