是否有Scala替代Guava MultiSet和Table概念? [英] Is there a scala replacement for Guava MultiSet and Table concepts?

问题描述

要在Scala中使用番石榴Table和Multiset吗?在scala中已经有不同的概念，而不是为此目的导入番石榴库吗?

To use guava Table and Multiset in scala? are there already different concenpts in scala instead of importing guava library for this usage?

推荐答案

您可以使用Map[(R, C), V]代替Table<R, C, V>，使用Map[T, Int]代替Multiset<T>.您还可以像这样将辅助方法添加到Map[T, Int]:

You could use Map[(R, C), V] instead of Table<R, C, V> and Map[T, Int] instead of Multiset<T>. You could also add helper methods to Map[T, Int] like this:

implicit class Multiset[T](val m: Map[T, Int]) extends AnyVal {
  def setAdd(e: T, i: Int = 1) = {
    val cnt = m.getOrElse(e, 0) + i
    if (cnt <= 0) m - e
    else m.updated(e, cnt)
  }
  def setRemove(e: T, i: Int = 1) = setAdd(e, -i)
  def count(e: T) = m.getOrElse(e, 0)
}

val m = Map('a -> 5)

m setAdd 'a
// Map('a -> 6)

m setAdd 'b
// Map('a -> 5, 'b -> 1)

m setAdd ('b, 10)
// Map('a -> 5, 'b -> 10)

m setRemove 'a
// Map('a -> 4)

m setRemove ('a, 6)
// Map()

m count 'b
// 0

(m setAdd 'a) count 'a
// 6

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