golang按字段排序
raoxiaoya 人气:0概述
golang的sort包默认支持int, float64, string的从小大到排序：
int -> Ints(x []int)
float64 -> Float64s(x []float64)
string -> Strings(x []string)
同时它还提供了自定义的排序接口Interface，此接口保护三个方法。
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)
}
golang默认提供了三个类型，他们都实现了Interface：
Float64Slice
IntSlice
StringSlice
从大到小排序
方法1：先使用提供的从大到小排序，再翻转
arr := []float64{0.1, 0.5, 0.8, 0.4, 0.2}
sort.Sort(sort.Reverse(sort.Float64Slice(arr)))
fmt.Println(arr) // [0.8 0.5 0.4 0.2 0.1]方法二：自定义类型实现
type Float64SliceDecrement []float64
func (s Float64SliceDecrement) Len() int { return len(s) }
func (s Float64SliceDecrement) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
func (s Float64SliceDecrement) Less(i, j int) bool { return s[i] > s[j] }
func main() {
arr := []float64{0.1, 0.5, 0.8, 0.4, 0.2}
sort.Sort(Float64SliceDecrement(arr))
fmt.Println(arr) // [0.8 0.5 0.4 0.2 0.1]
}
按照结构体的某个字段排序
按年纪从大到小排序
type Persons struct {
Age int
Height int
}
type PersonsSliceDecrement []Persons
func (s PersonsSliceDecrement) Len() int { return len(s) }
func (s PersonsSliceDecrement) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
func (s PersonsSliceDecrement) Less(i, j int) bool { return s[i].Age > s[j].Age }
func main() {
arr1 := []Persons{
Persons{10, 12},
Persons{20, 12},
Persons{9, 12},
Persons{10, 12},
Persons{11, 12},
}
sort.Sort(PersonsSliceDecrement(arr1))
fmt.Println(arr1)
}
打印
[{20 12} {11 12} {10 12} {10 12} {9 12}]
按年纪从大到小，如果年纪相等的，按身高从小到到
type Persons struct {
Age int
Height int
}
type PersonsSliceDecrement []Persons
func (s PersonsSliceDecrement) Len() int { return len(s) }
func (s PersonsSliceDecrement) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
func (s PersonsSliceDecrement) Less(i, j int) bool {
if s[i].Age > s[j].Age {
return true
}
if s[i].Age == s[j].Age && s[i].Height < s[j].Height {
return true
}
return false
}
func main() {
arr1 := []Persons{
Persons{10, 120},
Persons{20, 12},
Persons{10, 110},
Persons{10, 11},
Persons{10, 100},
}
sort.Sort(PersonsSliceDecrement(arr1))
fmt.Println(arr1)
}
打印
[{20 12} {10 11} {10 100} {10 110} {10 120}]
使用 sort.Stable 进行稳定排序
sort.Sort 并不保证排序的稳定性。如果有需要, 可以使用 sort.Stable ，用法就是将sort.Sort 替换为 sort.Stable
附：go根据结构体中任意字段进行排序
附：根据结构体中任意字段进行排序
Sort()
Reverse()
Less(i,j int) bool
Len() int
Swap(i,j int)
package main
import (
"fmt"
"sort"
)
type Student struct {
Number string
Name string
Age int
IsWalker bool
Weight float32
}
type ByNumber []*Student
func (this ByNumber)Len() int {
return len(this)
}
func (this ByNumber)Less(i,j int) bool {
return this[i].Number<this[j].Number
}
func (this ByNumber)Swap(i,j int) {
this[i],this[j] = this[j],this[i]
}
func (this ByNumber) String() string {
const format = "| %v |\t%v |\t%v |\t %v |\t %v |\t%v |\n"
fmt.Println("\t\t\t\t\t学生信息表")
fmt.Println(" 序号\t学号 \t姓名\t 年龄\t 体重\t 是否走读")
for k,v:=range this{
fmt.Printf(format,k+1,v.Number,v.Name,v.Age,v.Weight,v.IsWalker)
}
return ""
}
func main1() {
sts:=[]*Student{
&Student{Number: "003",Name: "张三"},
&Student{Number: "004",Name: "张四"},
&Student{Number: "001",Name: "张一"},
&Student{Number: "002",Name: "张二"},
&Student{Number: "000",Name: "张零"},
}
b:=ByNumber(sts)
sort.Sort(b)
fmt.Println(b)
fmt.Println("反转")
sort.Sort(sort.Reverse(b)) //反转的用法
fmt.Println(b)
//为结构体内的每一个字段都绑定一个排序的外壳，这种操作显然不是很聪明
//这时候使用组合来解决这个问题
}
type customSort struct {
s []*Student
less func(i,j *Student) bool
}
func (this *customSort)Len() int {
return len(this.s)
}
func (this *customSort)Swap(i,j int) {
this.s[i],this.s[j] = this.s[j],this.s[i]
}
func (this *customSort)Less(i,j int) bool {
return this.less(this.s[i],this.s[j])
}
func main() {
sts:=[]*Student{
&Student{Number: "003",Name: "张三"},
&Student{Number: "004",Name: "张四"},
&Student{Number: "001",Name: "张一"},
&Student{Number: "000",Name: "张二"},
&Student{Number: "002",Name: "张二"},
}
c:=&customSort{
s: sts,
less: func(i, j *Student) bool {
if i.Number != j.Number { //可以指定多种排序规则
return i.Number>j.Number
}
if i.Name!=j.Name{
return i.Name<j.Name
}
return false
},
}
/*
package sort
// A type, typically a collection, that satisfies sort.Interface can be
// sorted by the routines in this package. The methods require that the
// elements of the collection be enumerated by an integer index.
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)
}
*/
sort.Sort(c) //Sort方法中不只能放slice类型，还可以放结构体类型,只要改类型 实现 Sort接口
fmt.Println(ByNumber(sts)) //单纯的使用一下ByNumber中重写是String()方法
}总结
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