Scala 划分一个集合

Question

我正在研究如何根据第三组的内容将一组分成两部分。我偶然发现了这个解决方案：

val s = Set(1,2,3)
val s2 = Set(4,5,6)
val s3 = s ++ s2

s3.partition(s)
res0: (scala.collection.immutable.Set[Int],scala.collection.immutable.Set[Int]) = (Set(1, 2, 3),Set(5, 6, 4))

partition的签名如下：

def partition(p: A => Boolean): (Repr, Repr)

有人可以向我解释提供集合而不是函数的工作原理吗？

提前致谢

Answer 1

一个集合s: Set[A]是一个函数A => Boolean：对于A的任意值a你return s是否包含a。

scala> val f: Int => Boolean = Set(1,2,3)
f: Int => Boolean = Set(1, 2, 3)

scala> f(1)
res0: Boolean = true

scala> f(4)
res1: Boolean = false

如果你看 documentation for .apply，你会看到

def apply(elem: A): Boolean
Tests if some element is contained in this set.

This method is equivalent to contains. It allows sets to be interpreted as predicates.

Scala 划分一个集合

Scala partition a set

scala

set

partition