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60 lines
2.0 KiB
Markdown
60 lines
2.0 KiB
Markdown
#8.5 map排序
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map默认是无序的，不管是按照key还是按照value默认都不排序（参见8.3节）
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如果你想为map排序，需要将key（或者value）拷贝到一个slice，再对slice排序（使用sort包，参见7.6.6），然后可以使用slice的for-range方法打印出所有的key和value。
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下面有一个示例：
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示例 8.6 [sort_map.go](examples/chapter_8/sort_map.go)
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// the telephone alphabet:
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package main
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import (
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"fmt"
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"sort"
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)
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var (
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barVal = map[string]int{"alpha": 34, "bravo": 56, "charlie": 23,
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"delta": 87, "echo": 56, "foxtrot": 12,
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"golf": 34, "hotel": 16, "indio": 87,
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"juliet": 65, "kili": 43, "lima": 98}
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)
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func main() {
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fmt.Println("unsorted:")
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for k, v := range barVal {
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fmt.Printf("Key: %v, Value: %v / ", k, v)
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}
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keys := make([]string, len(barVal))
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i := 0
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for k, _ := range barVal {
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keys[i] = k
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i++
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}
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sort.Strings(keys)
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fmt.Println()
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fmt.Println("sorted:")
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for _, k := range keys {
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fmt.Printf("Key: %v, Value: %v / ", k, barVal[k])
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}
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}
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输出结果：
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unsorted:
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Key: bravo, Value: 56 / Key: echo, Value: 56 / Key: indio, Value: 87 / Key: juliet, Value: 65 / Key: alpha, Value: 34 / Key: charlie, Value: 23 / Key: delta, Value: 87 / Key: foxtrot, Value: 12 / Key: golf, Value: 34 / Key: hotel, Value: 16 / Key: kili, Value: 43 / Key: lima, Value: 98 /
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sorted:
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Key: alpha, Value: 34 / Key: bravo, Value: 56 / Key: charlie, Value: 23 / Key: delta, Value: 87 / Key: echo, Value: 56 / Key: foxtrot, Value: 12 / Key: golf, Value: 34 / Key: hotel, Value: 16 / Key: indio, Value: 87 / Key: juliet, Value: 65 / Key: kili, Value: 43 / Key: lima, Value: 98 / [fangjun@st01-dstream-0001.st01.baidu.com go]$ sz -be sort_map.go
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但是如果你想要一个排序的列表你最好使用结构体slice，这样会更有效：
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type struct {
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key string
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value int
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}
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##链接
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- [目录](directory.md)
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- 上一节：[maps分片](08.4.md)
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- 下一节：[倒置map](08.6.md)
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