golang convert slice{0,1,2,3,4} to slice{1,2,3}?

I have dynamic slice of strings for example {"0s", "1s", "2s", "3s", "4s"}.
And I have dynamic slice of indexes for example {1, 2, 3}.
So i need only elements with index 1, 2 and 3 in slice.
Note both indexes slice and data slice are dynamic.

package main

import (
	"fmt"
)

func main() {
	indexes := []uint8{1, 2, 3}              //dynamic slice. maybe different elements and count
	data := []string{"0s", "1s", "2s", "3s", } //dynamic slice. maybe different elements and count

	// I need convert data to {"1s", "2s", "3s"} using indexes (dynamic) slice
	fmt.Println(data)
	fmt.Println(indexes)
}

here playground url https://play.golang.org/p/Vj0Vl5va4LP

To create a new data slice with index values retrieved from index slice ,you have to iterate the index slice and pass the value of index slice as index of data slice.Below is the code with this logic

package main

import (
	"fmt"
)

func main() {
	indexes := []uint8{1, 2, 3}
	data := []string{"0s", "1s", "2s", "3s"}
	var newData []string

	fmt.Println(data)
	fmt.Println(indexes)

	for _, v2 := range indexes {

		newData = append(newData, data[v2])
	}
	fmt.Println(newData)
}

Output :

[0s 1s 2s 3s]
[1 2 3]
[1s 2s 3s]

Please note - your index slice is of type []uint8 - which is fine, but limits you to slices of max-length 256. This may be by design, but just something to be aware of.

Other solutions here use append - which is fine for small slices. But in general, when dealing with slices, if you know the final slice length, it is best to pre-allocate and write directly to indices and avoid append potentially performing multiple reallocations:

func correlate(vs []string, is []uint8) (s []string) {
	s = make([]string, len(is)) // pre-allocate results length - to avoid using append

	for j, i := range is {
		s[j] = vs[i]
	}
	return
}

https://play.golang.org/p/Et2VyoZzo59

Here is a general solution that retrieves only the matched elements and discard if out of range.
https://play.golang.org/p/34vQnNh0jd4

func getElementsByIndexes(data []string, indexes []uint8) []string {
	res := make([]string, 0)
	l := len(data)
	
	for _, v := range indexes {	
        // discard if out of range
	    if int(v) >= l {
		    continue
	    }
	
	    res = append(res, data[int(v)])
	}

	return res
}

</details>



# 答案4
**得分**: 0

我来翻译一下：

我找到了一个相当简单的解决方案：

```go
func filterByIndexes(sl []string, ind []int) []string {
    var filteredSlice []string
    for index := range ind {
        // 你可能想要检查索引是否超出范围 :)
        filteredSlice = append(filteredSlice, sl[index])
    }
    return filteredSlice
}

如注释所述，你可能想要检查索引是否超出范围！

func filterByIndexes(sl []string, ind []int)[]string{
var filteredSlice []string
for index := range ind{
	// you may want to check for index out of range :)
	filteredSlice = append(filteredSlice, sl[index])
}
return filteredSlice