如何优雅地将数组的一部分复制到另一个数组中或注入到另一个数组中

Question

我有以下有效的代码，但这里的要点是我想将一个任意长度的数组注入或插入到另一个扩展其长度的静态大小的数组中：package mainimport (    "fmt")func main() {    ffmpegArguments := []string{        "-y",        "-i", "invideo",        // ffmpegAudioArguments...,        "-c:v", "copy",        "-strict", "experimental",        "outvideo",    }    var outputArguments [12]string    copy(outputArguments[0:3], ffmpegArguments[0:3])    copy(outputArguments[3:7], []string{"-i", "inaudio", "-c:a", "aac"})    copy(outputArguments[7:12], ffmpegArguments[3:8])    fmt.Printf("%#v\n", ffmpegArguments)    fmt.Printf("%#v\n", outputArguments)}https://play.golang.org/p/peQXkOpheK4

Answer 1

讲优雅有些自以为是，但可以提出KISS原则。顺便说一句，您可以对切片使用更简单的方法，不需要您猜测输出数组的大小：

func inject(haystack, pile []string, at int) []string {

    result := haystack[:at]

    result = append(result, pile...)

    result = append(result, haystack[at:]...)

    return result

}

并且，按如下方式重写您的代码：

ffmpegArguments := []string{

    "-y",

    "-i", "invideo",

    "-c:v", "copy",

    "-strict", "experimental",

    "outvideo",

}

outputArguments := inject(ffmpegArguments, []string{"-i", "inaudio", "-c:a", "aac"}, 3)

fmt.Printf("%#v\n", ffmpegArguments)

fmt.Printf("%#v\n", outputArguments)

Answer 2

由于您要附加到输出，我建议这样做（简单且一致）并设置最大容量：

out := make([]string, 0, 12)

out = append(out, in[0:3]...)

out = append(out, []string{"-i", "inaudio", "-c:a", "aac"}...)

out = append(out, in[3:8]...)

看：

package main

import (

    "fmt"

)

func main() {

    in := []string{

        "-y",

        "-i", "invideo",

        // ffmpegAudioArguments...,

        "-c:v", "copy",

        "-strict", "experimental",

        "outvideo",

    }

    out := make([]string, 0, 12)

    out = append(out, in[0:3]...)

    out = append(out, []string{"-i", "inaudio", "-c:a", "aac"}...)

    out = append(out, in[3:8]...)

    fmt.Println(in)

    fmt.Println(out)

}

结果：

[-y -i invideo -c:v copy -strict experimental outvideo]

[-y -i invideo -i inaudio -c:a aac -c:v copy -strict experimental outvideo]

Answer 3

看起来第一个赋值指向 haystack 数组，随后的步骤修改了切片haystack：

// arrayInject is a helper function written by Alirus on StackOverflow in my

// inquiry to find a way to inject one array into another _elegantly_:

func arrayInject(haystack, pile []string, at int) (result []string) {

    result = make([]string, len(haystack[:at]))

    copy(result, haystack[:at])

    result = append(result, pile...)

    result = append(result, haystack[at:]...)

    return result

}