# package sort
`import "sort"`
sort包提供了排序切片和用戶自定義數據集的函數。
Example
```
package sort_test
import (
"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 []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 Example() {
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]
}
```
Example (SortKeys)
```
package sort_test
import (
"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 Example_sortKeys() {
// 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)
// Output: By name: [{Earth 1 1} {Mars 0.107 1.5} {Mercury 0.055 0.4} {Venus 0.815 0.7}]
// By mass: [{Mercury 0.055 0.4} {Mars 0.107 1.5} {Venus 0.815 0.7} {Earth 1 1}]
// By distance: [{Mercury 0.055 0.4} {Venus 0.815 0.7} {Earth 1 1} {Mars 0.107 1.5}]
// By decreasing distance: [{Mars 0.107 1.5} {Earth 1 1} {Venus 0.815 0.7} {Mercury 0.055 0.4}]
}
```
Example (SortMultiKeys)
```
package sort_test
import (
"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 int
for 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 true
case 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 Example_sortMultiKeys() {
// 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)
// Output:
// By user: [{dmr C 100} {glenda Go 200} {gri Smalltalk 80} {gri Go 100} {ken Go 200} {ken C 150} {r Go 100} {r C 150} {rsc Go 200}]
// By user,<lines: [{dmr C 100} {glenda Go 200} {gri Smalltalk 80} {gri Go 100} {ken C 150} {ken Go 200} {r Go 100} {r C 150} {rsc Go 200}]
// By user,>lines: [{dmr C 100} {glenda Go 200} {gri Go 100} {gri Smalltalk 80} {ken Go 200} {ken C 150} {r C 150} {r Go 100} {rsc Go 200}]
// By language,<lines: [{dmr C 100} {ken C 150} {r C 150} {gri Go 100} {r Go 100} {ken Go 200} {glenda Go 200} {rsc Go 200} {gri Smalltalk 80}]
// By language,<lines,user: [{dmr C 100} {ken C 150} {r C 150} {gri Go 100} {r Go 100} {glenda Go 200} {ken Go 200} {rsc Go 200} {gri Smalltalk 80}]
}
```
Example (SortWrapper)
```
package sort_test
import (
"fmt"
"sort"
)
type Grams int
func (g Grams) String() string { return fmt.Sprintf("%dg", int(g)) }
type Organ struct {
Name string
Weight Grams
}
type Organs []*Organ
func (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 Example_sortWrapper() {
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)
// Output:
// Organs by weight:
// prostate (62g)
// pancreas (131g)
// spleen (162g)
// heart (290g)
// brain (1340g)
// liver (1494g)
// Organs by name:
// brain (1340g)
// heart (290g)
// liver (1494g)
// pancreas (131g)
// prostate (62g)
// spleen (162g)
}
func printOrgans(s []*Organ) {
for _, o := range s {
fmt.Printf("%-8s (%v)\n", o.Name, o.Weight)
}
}
```
## Index
* [type Interface](#Interface)
* [type IntSlice](#IntSlice)
* [func (p IntSlice) Len() int](#IntSlice.Len)
* [func (p IntSlice) Less(i, j int) bool](#IntSlice.Less)
* [func (p IntSlice) Search(x int) int](#IntSlice.Search)
* [func (p IntSlice) Sort()](#IntSlice.Sort)
* [func (p IntSlice) Swap(i, j int)](#IntSlice.Swap)
* [type Float64Slice](#Float64Slice)
* [func (p Float64Slice) Len() int](#Float64Slice.Len)
* [func (p Float64Slice) Less(i, j int) bool](#Float64Slice.Less)
* [func (p Float64Slice) Search(x float64) int](#Float64Slice.Search)
* [func (p Float64Slice) Sort()](#Float64Slice.Sort)
* [func (p Float64Slice) Swap(i, j int)](#Float64Slice.Swap)
* [type StringSlice](#StringSlice)
* [func (p StringSlice) Len() int](#StringSlice.Len)
* [func (p StringSlice) Less(i, j int) bool](#StringSlice.Less)
* [func (p StringSlice) Search(x string) int](#StringSlice.Search)
* [func (p StringSlice) Sort()](#StringSlice.Sort)
* [func (p StringSlice) Swap(i, j int)](#StringSlice.Swap)
* [func Ints(a []int)](#Ints)
* [func IntsAreSorted(a []int) bool](#IntsAreSorted)
* [func SearchInts(a []int, x int) int](#SearchInts)
* [func Float64s(a []float64)](#Float64s)
* [func Float64sAreSorted(a []float64) bool](#Float64sAreSorted)
* [func SearchFloat64s(a []float64, x float64) int](#SearchFloat64s)
* [func Strings(a []string)](#Strings)
* [func StringsAreSorted(a []string) bool](#StringsAreSorted)
* [func SearchStrings(a []string, x string) int](#SearchStrings)
* [func Sort(data Interface)](#Sort)
* [func Stable(data Interface)](#Stable)
* [func Reverse(data Interface) Interface](#Reverse)
* [func IsSorted(data Interface) bool](#IsSorted)
* [func Search(n int, f func(int) bool) int](#Search)
### Examples
* [Ints](#example-Ints)
* [Reverse](#example-Reverse)
* [package](#example-package)
* [package (SortKeys)](#example-package--SortKeys)
* [package (SortMultiKeys)](#example-package--SortMultiKeys)
* [package (SortWrapper)](#example-package--SortWrapper)
## type [Interface](https://github.com/golang/go/blob/master/src/sort/sort.go#L12 "View Source")
```
type Interface interface {
// Len方法返回集合中的元素個數
Len() int
// Less方法報告索引i的元素是否比索引j的元素小
Less(i, j int) bool
// Swap方法交換索引i和j的兩個元素
Swap(i, j int)
}
```
一個滿足sort.Interface接口的（集合）類型可以被本包的函數進行排序。方法要求集合中的元素可以被整數索引。
## type [IntSlice](https://github.com/golang/go/blob/master/src/sort/sort.go#L233 "View Source")
```
type IntSlice []int
```
IntSlice給[]int添加方法以滿足Interface接口，以便排序為遞增序列。
### func (IntSlice) [Len](https://github.com/golang/go/blob/master/src/sort/sort.go#L235 "View Source")
```
func (p IntSlice) Len() int
```
### func (IntSlice) [Less](https://github.com/golang/go/blob/master/src/sort/sort.go#L236 "View Source")
```
func (p IntSlice) Less(i, j int) bool
```
### func (IntSlice) [Swap](https://github.com/golang/go/blob/master/src/sort/sort.go#L237 "View Source")
```
func (p IntSlice) Swap(i, j int)
```
### func (IntSlice) [Sort](https://github.com/golang/go/blob/master/src/sort/sort.go#L240 "View Source")
```
func (p IntSlice) Sort()
```
Sort等價于調用Sort(p)
### func (IntSlice) [Search](https://github.com/golang/go/blob/master/src/sort/search.go#L106 "View Source")
```
func (p IntSlice) Search(x int) int
```
Search等價于調用SearchInts(p, x)
## type [Float64Slice](https://github.com/golang/go/blob/master/src/sort/sort.go#L243 "View Source")
```
type Float64Slice []float64
```
Float64Slice給[]float64添加方法以滿足Interface接口，以便排序為遞增序列。
### func (Float64Slice) [Len](https://github.com/golang/go/blob/master/src/sort/sort.go#L245 "View Source")
```
func (p Float64Slice) Len() int
```
### func (Float64Slice) [Less](https://github.com/golang/go/blob/master/src/sort/sort.go#L246 "View Source")
```
func (p Float64Slice) Less(i, j int) bool
```
### func (Float64Slice) [Swap](https://github.com/golang/go/blob/master/src/sort/sort.go#L247 "View Source")
```
func (p Float64Slice) Swap(i, j int)
```
### func (Float64Slice) [Sort](https://github.com/golang/go/blob/master/src/sort/sort.go#L255 "View Source")
```
func (p Float64Slice) Sort()
```
Sort等價于調用Sort(p)
### func (Float64Slice) [Search](https://github.com/golang/go/blob/master/src/sort/search.go#L109 "View Source")
```
func (p Float64Slice) Search(x float64) int
```
Search等價于調用SearchFloat64s(p, x)
## type [StringSlice](https://github.com/golang/go/blob/master/src/sort/sort.go#L258 "View Source")
```
type StringSlice []string
```
StringSlice給[]string添加方法以滿足Interface接口，以便排序為遞增序列。
### func (StringSlice) [Len](https://github.com/golang/go/blob/master/src/sort/sort.go#L260 "View Source")
```
func (p StringSlice) Len() int
```
### func (StringSlice) [Less](https://github.com/golang/go/blob/master/src/sort/sort.go#L261 "View Source")
```
func (p StringSlice) Less(i, j int) bool
```
### func (StringSlice) [Swap](https://github.com/golang/go/blob/master/src/sort/sort.go#L262 "View Source")
```
func (p StringSlice) Swap(i, j int)
```
### func (StringSlice) [Sort](https://github.com/golang/go/blob/master/src/sort/sort.go#L265 "View Source")
```
func (p StringSlice) Sort()
```
Sort等價于調用Sort(p)
### func (StringSlice) [Search](https://github.com/golang/go/blob/master/src/sort/search.go#L112 "View Source")
```
func (p StringSlice) Search(x string) int
```
Search等價于調用SearchStrings(p, x)
## func [Sort](https://github.com/golang/go/blob/master/src/sort/sort.go#L192 "View Source")
```
func Sort(data Interface)
```
Sort排序data。它調用1次data.Len確定長度，調用O(n\*log(n))次data.Less和data.Swap。本函數不能保證排序的穩定性（即不保證相等元素的相對次序不變）。
## func [Stable](https://github.com/golang/go/blob/master/src/sort/sort.go#L317 "View Source")
```
func Stable(data Interface)
```
Stable排序data，并保證排序的穩定性，相等元素的相對次序不變。
它調用1次data.Len，O(n\*log(n))次data.Less和O(n\*log(n)\*log(n))次data.Swap。
## func [IsSorted](https://github.com/golang/go/blob/master/src/sort/sort.go#L220 "View Source")
```
func IsSorted(data Interface) bool
```
IsSorted報告data是否已經被排序。
## func [Reverse](https://github.com/golang/go/blob/master/src/sort/sort.go#L215 "View Source")
```
func Reverse(data Interface) Interface
```
Reverse包裝一個Interface接口并返回一個新的Interface接口，對該接口排序可生成遞減序列。
Example
```
s := []int{5, 2, 6, 3, 1, 4} // unsorted
sort.Sort(sort.Reverse(sort.IntSlice(s)))
fmt.Println(s)
```
Output:
```
[6 5 4 3 2 1]
```
## func [Search](https://github.com/golang/go/blob/master/src/sort/search.go#L59 "View Source")
```
func Search(n int, f func(int) bool) int
```
Search函數采用二分法搜索找到[0, n)區間內最小的滿足f(i)==true的值i。也就是說，Search函數希望f在輸入位于區間[0, n)的前面某部分（可以為空）時返回假，而在輸入位于剩余至結尾的部分（可以為空）時返回真；Search函數會返回滿足f(i)==true的最小值i。如果沒有該值，函數會返回n。注意，未找到時的返回值不是-1，這一點和strings.Index等函數不同。Search函數只會用區間[0, n)內的值調用f。
一般使用Search找到值x在插入一個有序的、可索引的數據結構時，應插入的位置。這種情況下，參數f（通常是閉包）會捕捉應搜索的值和被查詢的數據集。
例如，給定一個遞增順序的切片，調用Search(len(data), func(i int) bool { return data[i] >= 23 })會返回data中最小的索引i滿足data[i] >= 23。如果調用者想要知道23是否在切片里，它必須另外檢查data[i] == 23。
搜索遞減順序的數據時，應使用<=運算符代替>=運算符。
下列代碼嘗試在一個遞增順序的整數切片中找到值x：
```
x := 23
i := 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.
}
```
一個更古怪的例子，下面的程序會猜測你持有的數字：
```
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)
}
```
## func [Ints](https://github.com/golang/go/blob/master/src/sort/sort.go#L270 "View Source")
```
func Ints(a []int)
```
Ints函數將a排序為遞增順序。
Example
```
s := []int{5, 2, 6, 3, 1, 4} // unsorted
sort.Ints(s)
fmt.Println(s)
```
Output:
```
[1 2 3 4 5 6]
```
## func [IntsAreSorted](https://github.com/golang/go/blob/master/src/sort/sort.go#L279 "View Source")
```
func IntsAreSorted(a []int) bool
```
IntsAreSorted檢查a是否已排序為遞增順序。
## func [SearchInts](https://github.com/golang/go/blob/master/src/sort/search.go#L83 "View Source")
```
func SearchInts(a []int, x int) int
```
SearchInts在遞增順序的a中搜索x，返回x的索引。如果查找不到，返回值是x應該插入a的位置（以保證a的遞增順序），返回值可以是len(a)。
## func [Float64s](https://github.com/golang/go/blob/master/src/sort/sort.go#L273 "View Source")
```
func Float64s(a []float64)
```
Float64s函數將a排序為遞增順序。
## func [Float64sAreSorted](https://github.com/golang/go/blob/master/src/sort/sort.go#L282 "View Source")
```
func Float64sAreSorted(a []float64) bool
```
Float64sAreSorted檢查a是否已排序為遞增順序。
## func [SearchFloat64s](https://github.com/golang/go/blob/master/src/sort/search.go#L92 "View Source")
```
func SearchFloat64s(a []float64, x float64) int
```
SearchFloat64s在遞增順序的a中搜索x，返回x的索引。如果查找不到，返回值是x應該插入a的位置（以保證a的遞增順序），返回值可以是len(a)。
## func [Strings](https://github.com/golang/go/blob/master/src/sort/sort.go#L276 "View Source")
```
func Strings(a []string)
```
Strings函數將a排序為遞增順序。
## func [StringsAreSorted](https://github.com/golang/go/blob/master/src/sort/sort.go#L285 "View Source")
```
func StringsAreSorted(a []string) bool
```
StringsAreSorted檢查a是否已排序為遞增順序。
## func [SearchStrings](https://github.com/golang/go/blob/master/src/sort/search.go#L101 "View Source")
```
func SearchStrings(a []string, x string) int
```
SearchStrings在遞增順序的a中搜索x，返回x的索引。如果查找不到，返回值是x應該插入a的位置（以保證a的遞增順序），返回值可以是len(a)。
- 庫
- package achive
- package tar
- package zip
- package bufio
- package builtin
- package bytes
- package compress
- package bzip2
- package flate
- package gzip
- package lzw
- package zlib
- package container
- package heap
- package list
- package ring
- package crypto
- package aes
- package cipher
- package des
- package dsa
- package ecdsa
- package elliptic
- package hmac
- package md5
- package rand
- package rc4
- package rsa
- package sha1
- package sha256
- package sha512
- package subtle
- package tls
- package x509
- package pkix
- package database
- package sql
- package driver
- package encoding
- package ascii85
- package asn1
- package base32
- package base64
- package binary
- package csv
- package gob
- package hex
- package json
- package pem
- package xml
- package errors
- package expvar
- package flag
- package fmt
- package go
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