# golang切片排序sort包的使用
golang的sort包提供了部分切片排序的函数和用户自定义数据集的函数。
## 排序切片
```go
func Example1() {
arry := []int{5,8,3,1,4,2,7,6}
fmt.Println(arry)
sort.Ints(arry)
fmt.Println(arry)
// Output:
// [5 8 3 1 4 2 7 6]
// [1 2 3 4 5 6 7 8]
}
```
## 排序用户自定义数据集
```go
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 []Person
func (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 Example2() {
people := []Person{
{"Bob", 31},
{"John", 42},
{"Michael", 17},
{"Jenny", 26},
}
fmt.Println(people)
sort.Sort(ByAge(people))
fmt.Println(people)
// Output:
// [Bob: 31 John: 42 Michael: 17 Jenny: 26]
// [Michael: 17 Jenny: 26 Bob: 31 John: 42]
}
```
## 按选定的Key排序自定义数据集
```go
type stature float32
type weight float32
type Pepole struct {
name string
h stature
w weight
}
// By is the type of a "less" function that defines the ordering of its Pepole arguments.
type By func(p1, p2 *Pepole) bool
// Sort is a method on the function type, By, that sorts the argument slice according to the function.
func (by By) Sort(p []Pepole) {
ps := &pepoleSorter{
pepole: pepole,
by: by, // The Sort method's receiver is the function (closure) that defines the sort order.
}
sort.Sort(ps)
}
// pepoleSorter joins a By function and a slice of Pepole to be sorted.
type pepoleSorter struct {
pepole []Pepole
by func(p1, p2 *Pepole) bool // Closure used in the Less method.
}
// Len is part of sort.Interface.
func (s *pepoleSorter) Len() int {
return len(s.pepole)
}
// Swap is part of sort.Interface.
func (s *pepoleSorter) Swap(i, j int) {
s.pepole[i], s.pepole[j] = s.pepole[j], s.pepole[i]
}
// Less is part of sort.Interface. It is implemented by calling the "by" closure in the sorter.
func (s *pepoleSorter) Less(i, j int) bool {
return s.by(&s.pepole[i], &s.pepole[j])
}
var pepole = []Pepole{
{"Rose", 1.58, 66.6},
{"Daisley", 1.78, 58.4},
{"Lumiya", 1.65, 57.9},
{"Sola", 1.68, 55.77},
}
// ExampleSortKeys demonstrates a technique for sorting a struct type using programmable sort criteria.
func Example_sortKeys() {
// Closures that order the Planet structure.
name := func(p1, p2 *Pepole) bool {
return p1.name < p2.name
}
stature := func(p1, p2 *Pepole) bool {
return p1.h < p2.h
}
weight := func(p1, p2 *Pepole) bool {
return p1.w < p2.w
}
decreasingWeight := func(p1, p2 *Pepole) bool {
return !weight(p1, p2)
}
// Sort the pepole by the various criteria.
By(name).Sort(pepole)
fmt.Println("By name:", pepole)
By(stature).Sort(pepole)
fmt.Println("By stature:", pepole)
By(weight).Sort(pepole)
fmt.Println("By weight:", pepole)
By(decreasingWeight).Sort(pepole)
fmt.Println("By decreasing weight:", pepole)
// Output:
// By name: [{Daisley 1.78 58.4} {Lumiya 1.65 57.9} {Rose 1.58 66.6} {Sola 1.68 55.77}]
// By stature: [{Rose 1.58 66.6} {Lumiya 1.65 57.9} {Sola 1.68 55.77} {Daisley 1.78 58.4}]
// By weight: [{Sola 1.68 55.77} {Lumiya 1.65 57.9} {Daisley 1.78 58.4} {Rose 1.58 66.6}]
// By decreasing weight: [{Rose 1.58 66.6} {Daisley 1.78 58.4} {Lumiya 1.65 57.9} {Sola 1.68 55.77}]
}
```
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