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import "sort"
概况
索引
例子
程序包排序为排序切片和用户定义的集合提供原语。
package mainimport ("fmt""sort")type Person struct {
Name string
Age int}func (p Person) String() string {return fmt.Sprintf("%s: %d", p.Name, p.Age)}// ByAge implements sort.Interface for []Person based on// the Age field.type ByAge []Personfunc (a ByAge) Len() int { return len(a) }func (a ByAge) Swap(i, j int) { a[i], a[j] = a[j], a[i] }func (a ByAge) Less(i, j int) bool { return a[i].Age < a[j].Age }func main() {
people := []Person{{"Bob", 31},{"John", 42},{"Michael", 17},{"Jenny", 26},}
fmt.Println(people)
sort.Sort(ByAge(people))
fmt.Println(people)}ExampleSortKeys 演示了一种使用可编程排序标准对结构类型进行排序的技术。
package mainimport ("fmt""sort")// A couple of type definitions to make the units clear.type earthMass float64
type au float64// A Planet defines the properties of a solar system object.type Planet struct {
name string
mass earthMass
distance au}// By is the type of a "less" function that defines the ordering of its Planet arguments.type By func(p1, p2 *Planet) bool// Sort is a method on the function type, By, that sorts the argument slice according to the function.func (by By) Sort(planets []Planet) {
ps := &planetSorter{
planets: planets,
by: by, // The Sort method's receiver is the function (closure) that defines the sort order.}
sort.Sort(ps)}// planetSorter joins a By function and a slice of Planets to be sorted.type planetSorter struct {
planets []Planet
by func(p1, p2 *Planet) bool // Closure used in the Less method.}// Len is part of sort.Interface.func (s *planetSorter) Len() int {return len(s.planets)}// Swap is part of sort.Interface.func (s *planetSorter) Swap(i, j int) {
s.planets[i], s.planets[j] = s.planets[j], s.planets[i]}// Less is part of sort.Interface. It is implemented by calling the "by" closure in the sorter.func (s *planetSorter) Less(i, j int) bool {return s.by(&s.planets[i], &s.planets[j])}var planets = []Planet{{"Mercury", 0.055, 0.4},{"Venus", 0.815, 0.7},{"Earth", 1.0, 1.0},{"Mars", 0.107, 1.5},}// ExampleSortKeys demonstrates a technique for sorting a struct type using programmable sort criteria.func main() {// Closures that order the Planet structure.
name := func(p1, p2 *Planet) bool {return p1.name < p2.name}
mass := func(p1, p2 *Planet) bool {return p1.mass < p2.mass}
distance := func(p1, p2 *Planet) bool {return p1.distance < p2.distance}
decreasingDistance := func(p1, p2 *Planet) bool {return !distance(p1, p2)}// Sort the planets by the various criteria.By(name).Sort(planets)
fmt.Println("By name:", planets)By(mass).Sort(planets)
fmt.Println("By mass:", planets)By(distance).Sort(planets)
fmt.Println("By distance:", planets)By(decreasingDistance).Sort(planets)
fmt.Println("By decreasing distance:", planets)}ExampleMultiKeys 演示了一种技术，用于在比较中使用不同组的多个字段对结构类型进行排序。我们将“较少”功能链接在一起，每个功能都比较一个字段。
package mainimport ("fmt""sort")// A Change is a record of source code changes, recording user, language, and delta size.type Change struct {
user string
language string
lines int}type lessFunc func(p1, p2 *Change) bool// multiSorter implements the Sort interface, sorting the changes within.type multiSorter struct {
changes []Change
less []lessFunc}// Sort sorts the argument slice according to the less functions passed to OrderedBy.func (ms *multiSorter) Sort(changes []Change) {
ms.changes = changes
sort.Sort(ms)}// OrderedBy returns a Sorter that sorts using the less functions, in order.// Call its Sort method to sort the data.func OrderedBy(less ...lessFunc) *multiSorter {return &multiSorter{
less: less,}}// Len is part of sort.Interface.func (ms *multiSorter) Len() int {return len(ms.changes)}// Swap is part of sort.Interface.func (ms *multiSorter) Swap(i, j int) {
ms.changes[i], ms.changes[j] = ms.changes[j], ms.changes[i]}// Less is part of sort.Interface. It is implemented by looping along the// less functions until it finds a comparison that is either Less or// !Less. Note that it can call the less functions twice per call. We// could change the functions to return -1, 0, 1 and reduce the// number of calls for greater efficiency: an exercise for the reader.func (ms *multiSorter) Less(i, j int) bool {
p, q := &ms.changes[i], &ms.changes[j]// Try all but the last comparison.var k intfor k = 0; k < len(ms.less)-1; k++ {
less := ms.less[k]switch {case less(p, q):// p < q, so we have a decision.return truecase less(q, p):// p > q, so we have a decision.return false}// p == q; try the next comparison.}// All comparisons to here said "equal", so just return whatever// the final comparison reports.return ms.less[k](p, q)}var changes = []Change{{"gri", "Go", 100},{"ken", "C", 150},{"glenda", "Go", 200},{"rsc", "Go", 200},{"r", "Go", 100},{"ken", "Go", 200},{"dmr", "C", 100},{"r", "C", 150},{"gri", "Smalltalk", 80},}// ExampleMultiKeys demonstrates a technique for sorting a struct type using different// sets of multiple fields in the comparison. We chain together "Less" functions, each of// which compares a single field.func main() {// Closures that order the Change structure.
user := func(c1, c2 *Change) bool {return c1.user < c2.user}
language := func(c1, c2 *Change) bool {return c1.language < c2.language}
increasingLines := func(c1, c2 *Change) bool {return c1.lines < c2.lines}
decreasingLines := func(c1, c2 *Change) bool {return c1.lines > c2.lines // Note: > orders downwards.}// Simple use: Sort by user.OrderedBy(user).Sort(changes)
fmt.Println("By user:", changes)// More examples.OrderedBy(user, increasingLines).Sort(changes)
fmt.Println("By user,<lines:", changes)OrderedBy(user, decreasingLines).Sort(changes)
fmt.Println("By user,>lines:", changes)OrderedBy(language, increasingLines).Sort(changes)
fmt.Println("By language,<lines:", changes)OrderedBy(language, increasingLines, user).Sort(changes)
fmt.Println("By language,<lines,user:", changes)}package mainimport ("fmt""sort")type Grams intfunc (g Grams) String() string { return fmt.Sprintf("%dg", int(g)) }type Organ struct {
Name string
Weight Grams}type Organs []*Organfunc (s Organs) Len() int { return len(s) }func (s Organs) Swap(i, j int) { s[i], s[j] = s[j], s[i] }// ByName implements sort.Interface by providing Less and using the Len and// Swap methods of the embedded Organs value.type ByName struct{ Organs }func (s ByName) Less(i, j int) bool { return s.Organs[i].Name < s.Organs[j].Name }// ByWeight implements sort.Interface by providing Less and using the Len and// Swap methods of the embedded Organs value.type ByWeight struct{ Organs }func (s ByWeight) Less(i, j int) bool { return s.Organs[i].Weight < s.Organs[j].Weight }func main() {
s := []*Organ{{"brain", 1340},{"heart", 290},{"liver", 1494},{"pancreas", 131},{"prostate", 62},{"spleen", 162},}
sort.Sort(ByWeight{s})
fmt.Println("Organs by weight:")printOrgans(s)
sort.Sort(ByName{s})
fmt.Println("Organs by name:")printOrgans(s)}func printOrgans(s []*Organ) {for _, o := range s {
fmt.Printf("%-8s (%v)\n", o.Name, o.Weight)}}func Float64s(a []float64)
func Float64sAreSorted(a []float64) bool
func Ints(a []int)
func IntsAreSorted(a []int) bool
func IsSorted(data Interface) bool
func Search(n int, f func(int) bool) int
func SearchFloat64s(a []float64, x float64) int
func SearchInts(a []int, x int) int
func SearchStrings(a []string, x string) int
func Slice(slice interface{}, less func(i, j int) bool)
func SliceIsSorted(slice interface{}, less func(i, j int) bool) bool
func SliceStable(slice interface{}, less func(i, j int) bool)
func Sort(data Interface)
func Stable(data Interface)
func Strings(a []string)
func StringsAreSorted(a []string) bool
type Float64Slice
func (p Float64Slice) Len() int
func (p Float64Slice) Less(i, j int) bool
func (p Float64Slice) Search(x float64) int
func (p Float64Slice) Sort()
func (p Float64Slice) Swap(i, j int)
type IntSlice
func (p IntSlice) Len() int
func (p IntSlice) Less(i, j int) bool
func (p IntSlice) Search(x int) int
func (p IntSlice) Sort()
func (p IntSlice) Swap(i, j int)
type Interface
func Reverse(data Interface) Interface
type StringSlice
func (p StringSlice) Len() int
func (p StringSlice) Less(i, j int) bool
func (p StringSlice) Search(x string) int
func (p StringSlice) Sort()
func (p StringSlice) Swap(i, j int)
Package Ints 反向搜索搜索（DescendingOrder）SliceStable 字符串包（SortKeys）包（SortMultiKeys）包（SortWrapper）
search.go sort.go zfuncversion.go
func Float64s(a []float64)
Float64 以递增顺序对一片 float64 进行排序（非数字值被视为小于其他值）。
func Float64sAreSorted(a []float64) bool
Float64sAreSorted 测试是否按增量顺序对一段 float64 进行排序（非数字值被视为小于其他值）。
func Ints(a []int)
Ints 按递增顺序排序一部分整数。
package mainimport ("fmt""sort")func main() {
s := []int{5, 2, 6, 3, 1, 4} // unsorted
sort.Ints(s)
fmt.Println(s)}func IntsAreSorted(a []int) bool
IntsAreSorted 测试是否按升序对整片进行排序。
func IsSorted(data Interface) bool
IsSorted 报告数据是否被排序。
func Search(n int, f func(int) bool) int
假设在 [0，n），f（i）== true 的范围内，Search 使用二进制搜索来查找并返回 f（i）为真的 [0，n）中的最小索引 i，意味着 f（i + 1）== true 。也就是说，搜索要求 f 对于输入范围 [0，n）的某些（可能为空）前缀为假，对于（可能为空）余数为真; 搜索返回第一个真正的索引。如果没有这样的索引，Search 返回 n 。（请注意，“未找到”返回值不是-1，例如 strings.Index 。）仅在 i [0，n] 范围内搜索调用 f（i）。
Search 的一个常见用途是在排序的，可索引的数据结构（如数组或片段）中为值 x 找到索引 i 。在这种情况下，参数 f（通常是闭包）捕获要搜索的值，以及数据结构如何编制索引和排序。
例如，给定按升序排序的片数据，调用 Search（len（data），func（i int）bool { return datai> = 23}）返回最小的索引 i，使得 datai> = 23。如果调用者要查找23是否在分片中，它必须分别测试 datai == 23。
搜索按降序排序的数据将使用<=运算符而不是> =运算符。
为了完成上面的例子，下面的代码试图在一个整数片数据中按升序排序找到值 x：
x := 23i := sort.Search(len(data), func(i int) bool { return data[i] >= x })if i < len(data) && data[i] == x {// x is present at data[i]} else {// x is not present in data,// but i is the index where it would be inserted.}作为一个更奇特的例子，这个程序猜测你的号码：
func GuessingGame() {var s string
fmt.Printf("Pick an integer from 0 to 100.\n")
answer := sort.Search(100, func(i int) bool {
fmt.Printf("Is your number <= %d? ", i)
fmt.Scanf("%s", &s)return s != "" && s[0] == 'y'})
fmt.Printf("Your number is %d.\n", answer)}此示例演示如何搜索按升序排序的列表。
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)}}此示例演示搜索按降序排列的列表。该方法与按升序搜索列表相同，但条件反转。
package mainimport ("fmt""sort")func main() {
a := []int{55, 45, 36, 28, 21, 15, 10, 6, 3, 1}
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)}}func SearchFloat64s(a []float64, x float64) int
SearchFloat64s 在已排序的 float64s 片段中搜索 x，并返回 Search 所指定的索引。如果 x 不存在（它可能是len（a）），则返回值是插入x的索引。切片必须按升序排序。
func SearchInts(a []int, x int) int
SearchInts 在已排序的整数片段中搜索 x，并返回 Search 所指定的索引。如果 x 不存在（它可能是 len（a）），则返回值是插入 x 的索引。切片必须按升序排序。
func SearchStrings(a []string, x string) int
SearchStrings 在已排序的字符串片段中搜索 x，并返回 Search 所指定的索引。如果 x 不存在（它可能是 len（a）），则返回值是插入 x 的索引。切片必须按升序排序。
func Slice(slice interface{}, less func(i, j int) bool)由于提供了较少的功能，Slice 会对提供的切片进行排序。
排序不保证稳定。为了稳定排序，请使用 SliceStable。
如果提供的接口不是切片，则函数发生混乱。
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)}func SliceIsSorted(slice interface{}, less func(i, j int) bool) boolSliceIsSorted 测试是否对切片进行排序。
如果提供的接口不是切片，则函数发生混乱。
func SliceStable(slice interface{}, less func(i, j int) bool)SliceStable 根据提供的 less 函数对提供的 slice 进行排序，同时保持相同元素的原始顺序。
如果提供的接口不是切片，则函数发生混乱。
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)// 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)}func Sort(data Interface)
对排序数据进行排序。它调用 data.Len 来确定 n 和 O（n * log（n））对 data.Less 和 data.Swap 的调用。排序不保证稳定。
func Stable(data Interface)
稳定排序数据，同时保持相同元素的原始顺序。
它调用 data.Len 来确定调用 data.Less 和 O（n * log（n）* log（n））调用 data.Swap 的 n，O（n * log（n））调用。
func Strings(a []string)
Strings 按递增顺序排序一部分字符串。
package mainimport ("fmt""sort")func main() {
s := []string{"Go", "Bravo", "Gopher", "Alpha", "Grin", "Delta"}
sort.Strings(s)
fmt.Println(s)}func StringsAreSorted(a []string) bool
StringsAreSorted 测试一串字符串是否按递增顺序排序。
Float64Slice 将接口的方法附加到 [] float64，按递增顺序进行排序（非数字值被视为小于其他值）。
type Float64Slice []float64
func (p Float64Slice) Len() int
func (p Float64Slice) Less(i, j int) bool
func (p Float64Slice) Search(x float64) int
搜索返回应用 SearchFloat64s 到接收器和 x 的结果。
func (p Float64Slice) Sort()
排序是一种方便的方法。
func (p Float64Slice) Swap(i, j int)
IntSlice 将接口的方法附加到 [] int，按升序排序。
type IntSlice []int
func (p IntSlice) Len() int
func (p IntSlice) Less(i, j int) bool
func (p IntSlice) Search(x int) int
Search 返回将 SearchInts 应用于接收者和 x 的结果。
func (p IntSlice) Sort()
Sort 是一种方便的方法。
func (p IntSlice) Swap(i, j int)
一个类型，通常是一个集合，满足 sort.Interface 可以按照这个包中的例程进行排序。这些方法要求集合的元素由整数索引枚举。
type Interface interface { // Len is the number of elements in the collection. Len() int // Less reports whether the element with // index i should sort before the element with index j. Less(i, j int) bool // Swap swaps the elements with indexes i and j. Swap(i, j int)}func Reverse(data Interface) Interface
Reverse 返回数据的相反顺序。
package mainimport ("fmt""sort")func main() {
s := []int{5, 2, 6, 3, 1, 4} // unsorted
sort.Sort(sort.Reverse(sort.IntSlice(s)))
fmt.Println(s)}StringSlice 将接口的方法附加到 []字符串，按升序排序。
type StringSlice []string
func (p StringSlice) Len() int
func (p StringSlice) Less(i, j int) bool
func (p StringSlice) Search(x string) int
Search 返回将 SearchStrings 应用于接收者和 x 的结果。
func (p StringSlice) Sort()
Sort 是一种方便的方法。
func (p StringSlice) Swap(i, j int)