Sorting by Functions {.en}

按功能排序 {.zh}

::: {.en} Sometimes we’ll want to sort a collection by something other than its natural order. For example, suppose we wanted to sort strings by their length instead of alphabetically. Here’s an example of custom sorts in Go. :::

::: {.zh}

有时我们会想要通过除自然顺序以外的其他东西对集合进行排序。例如，假设我们希望按字母长度而不是按字母顺序对字符串进行排序。以下是自定义排序Go的示例。

:::

package main
import "sort"
import "fmt"

::: {.en} In order to sort by a custom function in Go, we need a corresponding type. Here we’ve created a byLength type that is just an alias for the builtin []string type. :::

::: {.zh}

为了按Go中的自定义函数排序，我们需要相应的类型。这里我们创建了一个byLengthtype，它只是内置[] stringtype的别名。

:::

type byLength []string

::: {.en} We implement sort.Interface - Len, Less, and Swap - on our type so we can use the sort package’s generic Sort function. Len and Swap will usually be similar across types and Less will hold the actual custom sorting logic. In our case we want to sort in order of increasing string length, so we use len(s[i]) and len(s[j]) here. :::

::: {.zh}

我们在类型上实现sort.Interface - Len，Less和Swap - 所以我们可以使用sort package’sgenericSorting函数。 Len和Swap通常在类型之间是相似的，而’Less将保留实际的自定义排序逻辑。在我们的例子中，我们想按照增加字符串长度的顺序排序，sowe在这里使用len（s [i]）和len（s [j]）`。

:::

func (s byLength) Len() int {
    return len(s)
}
func (s byLength) Swap(i, j int) {
    s[i], s[j] = s[j], s[i]
}
func (s byLength) Less(i, j int) bool {
    return len(s[i]) < len(s[j])
}

::: {.en} With all of this in place, we can now implement our custom sort by converting the original fruits slice to byLength, and then use sort.Sort on that typed slice. :::

::: {.zh}

有了所有这些，我们现在可以通过转换原始的fruits slicetobyLength来实现我们的自定义排序，然后在该typedlice上使用sort.Sort。

:::

func main() {
    fruits := []string{"peach", "banana", "kiwi"}
    sort.Sort(byLength(fruits))
    fmt.Println(fruits)
}

::: {.en} Running our program shows a list sorted by string length, as desired. :::

::: {.zh}

运行我们的程序会根据需要显示按stringlength排序的列表。

:::

$ go run sorting-by-functions.go 
[kiwi peach banana]

::: {.en} By following this same pattern of creating a custom type, implementing the three Interface methods on that type, and then calling sort.Sort on a collection of that custom type, we can sort Go slices by arbitrary functions. :::

::: {.zh}

通过遵循创建自定义类型的相同模式，在该类型上实现三个Interface方法，然后在该自定义类型的集合上调用sort.Sort，我们可以通过任意函数对Go切片进行排序。

:::