golang: 使用 sort 来排序
转置:https://blog.csdn.net/weixin_41918841/article/details/82898173
golang sort package: https://golang.org/src/sort
sort 操作的对象通常是一个 slice,需要满足三个基本的接口,并且能够使用整数来索引
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// A type, typically a collection, that satisfies sort.Interface can be
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// sorted by the routines in this package. The methods require that the
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// elements of the collection be enumerated by an integer index.
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type Interface interface {
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// Len is the number of elements in the collection.
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Len() int
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// Less reports whether the element with
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// index i should sort before the element with index j.
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Less(i, j int) bool
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// Swap swaps the elements with indexes i and j.
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Swap(i, j int)
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}
ex-1 对 []int 从小到大排序
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package main
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import (
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"fmt"
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"sort"
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)
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type IntSlice []int
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func (s IntSlice) Len() int { return len(s) }
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func (s IntSlice) Swap(i, j int){ s[i], s[j] = s[j], s[i] }
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func (s IntSlice) Less(i, j int) bool { return s[i] < s[j] }
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func main() {
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a := []int{4,3,2,1,5,9,8,7,6}
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sort.Sort(IntSlice(a))
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fmt.Println("After sorted: ", a)
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}
ex-2 使用 sort.Ints 和 sort.Strings
golang 对常见的 []int 和 []string 分别定义了 IntSlice 和 StringSlice, 实现了各自的排序接口。而
sort.Ints 和 sort.Strings 可以直接对 []int 和 []string 进行排序, 使用起来非常方便
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package main
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import (
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"fmt"
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"sort"
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)
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func main() {
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a := []int{3, 5, 4, -1, 9, 11, -14}
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sort.Ints(a)
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fmt.Println(a)
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ss := []string{"surface", "ipad", "mac pro", "mac air", "think pad", "idea pad"}
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sort.Strings(ss)
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fmt.Println(ss)
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sort.Sort(sort.Reverse(sort.StringSlice(ss)))
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fmt.Printf("After reverse: %v\n", ss)
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}
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ex-3 使用 sort.Reverse 进行逆序排序
如果我们想对一个 sortable object 进行逆序排序,可以自定义一个type。但 sort.Reverse 帮你省掉了这些代码
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package main
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import (
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"fmt"
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"sort"
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)
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func main() {
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a := []int{4,3,2,1,5,9,8,7,6}
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sort.Sort(sort.Reverse(sort.IntSlice(a)))
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fmt.Println("After reversed: ", a)
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}
ex-4 使用 sort.Stable 进行稳定排序
sort.Sort 并不保证排序的稳定性。如果有需要, 可以使用 sort.Stable
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package main
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import (
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"fmt"
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"sort"
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)
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type person struct {
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Name string
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Age int
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}
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type personSlice []person
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func (s personSlice) Len() int { return len(s) }
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func (s personSlice) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
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func (s personSlice) Less(i, j int) bool { return s[i].Age < s[j].Age }
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func main() {
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a := personSlice {
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{
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Name: "AAA",
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Age: 55,
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},
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{
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Name: "BBB",
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Age: 22,
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},
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{
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Name: "CCC",
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Age: 0,
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},
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{
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Name: "DDD",
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Age: 22,
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},
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{
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Name: "EEE",
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Age: 11,
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},
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}
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sort.Stable(a)
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fmt.Println(a)
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}