CODEWITHSUNDEEP
go
Jonathan S
Jonathan S

Reputation: 586

Slicing while unpacking slice

I have the following code

func Sum(a []int) int {
    res := 0
    for _, n := range a {
        res += n
    }
    return res
}

func SumAll(ns ...[]int) (sums []int) {
    for _, s := range ns {
        sums = append(sums, Sum(s))
    }
    return
}

//SumAllTails sums [:1] in each slice
func SumAllTails(sls ...[]int) []int {
    newsls := [][]int{}
    for _, sl := range sls {
        newsls = append(newsls, sl[1:])
    }
    return SumAll(newsls...)
}

Ideally I'd like to change the last function to be something like this

func SumAllTails(sls ...[]int) []int {
    return SumAll(sls[:][1:]...)
}

This last bit returns each slice but the first one, but what I'd like to do is unpack each slice from position 1 onwards, omitting the value at 0. Is there a way of achieving this in go?

Upvotes: 1

Views: 74

Answers (1)

Burak Serdar
Burak Serdar

Reputation: 51512

I think the only way to do what you want without going through the slices first is to write a SumAlln function:

func SumAlln(n int, ns ...[]int) (sums []int) {
    for _, s := range ns {
        sums = append(sums, Sum(s[n:]))
    }
    return
}

func SumAll(ns...[]int) []int {
    return SumAlln(0,ns...)
}

And then call SumAlln.

Upvotes: 3

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