Scala:Sorting.quickSort的相反顺序?

问题描述

此答案说明了如何使用内置方法.sortBy反转数组排序的顺序.使用scala.util.Sorting.quickSort时如何颠倒排序顺序?

This answer explains how to reverse the order of sorting an array while using its built-in method .sortBy. How do I reverse the order of the sorting when using scala.util.Sorting.quickSort?

推荐答案

像这样:

import scala.util.Sorting.quickSort

val a = Array(1, 2, 3)
quickSort[Int](a)(Ordering[Int].reverse)
//       ^---^ the most important bit
println(a.toVector) // Vector(3, 2, 1)

quickSort是一个对Int，Float和Double具有重载的函数，不允许您指定顺序，而对于具有Ordering实例的任何类型[T]的泛型函数

quickSort is a function that has overloads for Int, Float and Double, which don't let you specify ordering, and the generic one for any type [T] that has Ordering instance.

如果您有一个Int，Float或Double的数组，则重载解析将首选特殊版本，因此除非指定类型参数，否则您将无法手动传递Ordering(因此现在是编译器)只有一种选择.

If you have an array of Int, Float or Double, overload resolution will prefer specialized versions, so you will not be able to pass Ordering manually unless you specify a type parameter (so compiler now only has one choice).

对于除这三种类型(例如Long s)以外的其他事物的数组，您可以省略type参数，因为只有一个有效的选项:

For arrays of things other than these three types (e.g. Longs), you can omit the type parameter, because there's only one valid option:

val b = Array(1L, 2L, 3L)
quickSort(b)(Ordering[Long].reverse)
println(b.toVector) // Vector(3, 2, 1)

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