go笔记--切片排序sort包的使用

￡神魔★判官ぃ 2021-12-14 02:41 314阅读 0赞

# 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 ##

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 ##

\[外链图片转存失败(img-50ihtWcS-1562486268699)(./1562483367982.png)\]

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 ##

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}]
    }