Go 语言规范库提供了sort包,用于对切片和用户定义的汇合进行排序。
具体示例如下:

根本排序

package mainimport (    "fmt"    "sort")func main() {    //float 从小到大排序    f := []float64{5.2, -1.3, 0.7, -3.8, 2.6} // unsorted    sort.Float64s(f)    fmt.Println(f) //[-3.8 -1.3 0.7 2.6 5.2]    //float 倒序    sort.Sort(sort.Reverse(sort.Float64Slice(f)))    fmt.Println(f) //[5.2 2.6 0.7 -1.3 -3.8]    // int 正序 从小到大排序    i := []int{5, 6, 3, 7, 9} // unsorted    sort.Ints(i)    fmt.Println(i) //[3 5 6 7 9]    //int 倒序    sort.Sort(sort.Reverse(sort.IntSlice(i)))    fmt.Println(i) //[9 7 6 5 3]    //string 正序 字母程序    s := []string{"Go", "Bravo", "Gopher", "Alpha", "Grin", "Delta"}    sort.Strings(s)    fmt.Println(s) //[Alpha Bravo Delta Go Gopher Grin]    //int 倒序    sort.Sort(sort.Reverse(sort.StringSlice(s)))    fmt.Println(s) //[Grin Gopher Go Delta Bravo Alpha]}

在升序切片查找value

在已排序的切片中搜寻x,并返回由搜寻指定的索引。如果x不存在,返回值是要插入x的索引(它能够是len (a))。切片必须按升序排序。

package mainimport (    "fmt"    "sort")func main() {    //检索    a := []float64{1.0, 2.0, 3.3, 4.6, 6.1, 7.2, 8.0}    x := 1.0    i := sort.SearchFloat64s(a, x)    fmt.Printf("found %g at index %d in %v\n", x, i, a) //found 2 at index 1 in [1 2 3.3 4.6 6.1 7.2 8] 如果不存在返回0    a := []int{1, 2, 3, 4, 6, 7, 8}    b := []int{1, 2, 3, 4, 6, 7, 8}    y := 2    j := sort.SearchInts(b, y)    fmt.Printf("found %d at index %d in %v\n", y, j, b) //found 2 at index 1 in [1 2 3 4 6 7 8]    z := 1    i = sort.SearchInts(b, z)    fmt.Printf("%d not found, can be inserted at index %d in %v\n", z, i, b) //1 not found, can be inserted at index 0 in [1 2 3 4 6 7 8]}

留神这种状况,没有检索到和第一个索引的值都是零,所以返回值为0时不能作为检索不到某值为根据。

sort.slice

sort.Slice是go 1.8版本中引入的一个弱小排序函数,有两个参数,第一个参数是带排序any类型的切片,第二个参数是less函数,用于比拟大小,less 办法必须满足与接口类型的 Less 办法雷同的要求。
此排序不能保障是稳固的:相等的元素可能会从它们的原始程序颠倒过去。对于稳固排序,请应用 SliceStable。
示例:

package mainimport (    "fmt"    "sort")func main() {    people := []struct {        Name string        Age  int    }{        {"Gopher", 7},        {"Alice", 55},        {"Vera", 24},        {"Bob", 75},    }    sort.Slice(people, func(i, j int) bool { return people[i].Name < people[j].Name })    fmt.Println("By name:", people)    sort.Slice(people, func(i, j int) bool { return people[i].Age < people[j].Age })    fmt.Println("By age:", people)}

sort.SliceStable

sort.SliceStable是go 1.8版本中引入的一个弱小稳固的排序函数,应用提供的 less 函数对切片 x 进行排序,放弃相等元素的原始程序。

示例:

package mainimport (    "fmt"    "sort")func main() {    people := []struct {        Name string        Age  int    }{        {"Alice", 25},        {"Elizabeth", 75},        {"Alice", 75},        {"Bob", 75},        {"Alice", 75},        {"Bob", 25},        {"Colin", 25},        {"Elizabeth", 25},    }    // Sort by name, preserving original order    sort.SliceStable(people, func(i, j int) bool { return people[i].Name < people[j].Name })    fmt.Println("By name:", people)//By name: [{Alice 25} {Alice 75} {Alice 75} {Bob 75} {Bob 25} {Colin 25} {Elizabeth 75} {Elizabeth 25}]    // Sort by age preserving name order    sort.SliceStable(people, func(i, j int) bool { return people[i].Age < people[j].Age })    fmt.Println("By age,name:", people)//By age,name: [{Alice 25} {Bob 25} {Colin 25} {Elizabeth 25} {Alice 75} {Alice 75} {Bob 75} {Elizabeth 75}]}

Search

在按升序排序的整数切片数据中应用二分法进行查找值x,返回插入地位

package mainimport ("fmt""sort")func main() {a := []int{1, 3, 6, 10, 15, 21, 28, 36, 45, 55}x := 6    i := sort.Search(len(a), func(i int) bool { return a[i] >= x })    if i < len(a) && a[i] == x {        fmt.Printf("found %d at index %d in %v\n", x, i, a)    } else {        fmt.Printf("%d not found in %v\n", x, a)    }}

sort源码剖析

接口 type Interface

type Interface interface {    Len() int  //示意容器蕴含元素的个数。    Less(i, j int) bool //就是比拟函数    Swap(i, j int) //替换i 和 j.}

相干类型构造体

type Float64Slice []float64type IntSlice []inttype StringSlice []string

函数

func Ints(a []int)func IntsAreSorted(a []int) bool //是否排序//在按升序排序的整数切片数据中查找值x,留神如查到值第一个,返回的插入地位和查不到值都是0func SearchInts(a []int, x int) int //查找func Float64s(a []float64)func Float64sAreSorted(a []float64) bool ////在按升序排序的整数切片数据中查找值x,留神如查到值第一个,返回的插入地位和查不到值都是0func SearchFloat64s(a []float64, x float64) intfunc Strings(a []string)func StringsAreSorted(a []string) bool //是否排序//在按升序排序的整数切片数据中查找值x,留神如查到值第一个,返回的插入地位和查不到值都是0func SearchStrings(a []string, x string) intfunc Sort(data Interface)func Stable(data Interface)func Reverse(data Interface) Interfacefunc ISSorted(data Interface) bool//在按升序排序的整数切片数据中查找值x,返回的索引地位和查,第二个参数传入函数func Search(n int, f func(int) bool) int

sort用到的排序算法
插入排序(insertionSort_func)、归并排序(symMerge_func)、堆排序(heapSort_func)、疾速排序(pdqsort_func)、归并排序(symMerge_func)
sort会依据数据从以上四种算法选取一种高效的排序算法。
stable是稳固排序算法,采纳插入排序(insertionSort_func)和归并排序(symMerge_func)。
源码:

func stable_func(data lessSwap, n int) {    blockSize := 20 // must be > 0    a, b := 0, blockSize    for b <= n {        insertionSort_func(data, a, b)        a = b        b += blockSize    }    insertionSort_func(data, a, n)    for blockSize < n {        a, b = 0, 2*blockSize        for b <= n {            symMerge_func(data, a, a+blockSize, b)            a = b            b += 2 * blockSize        }        if m := a + blockSize; m < n {            symMerge_func(data, a, m, n)        }        blockSize *= 2    }}

links

https://pkg.go.dev/[email protected]