Split a 1D slice into 2D slice (triples)

main.go

package main

import "fmt"

func main() {
	s := []int{1, 2, 3, 4, 5, 6, 7, 8, 9}
	fmt.Println(split(s, 3))
}

func split(s []int, width int) [][]int {
	ss := make([][]int, len(s)/width)
	for si, wi := 0, 0; si < len(s); si, wi = si+3, wi+1 {
		ss[wi] = s[si:(si + width)]
	}
	return ss
}