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]