Golang: convert slices into map

Question

Is there an easy/simple means of converting a slice into a map in Golang? Like converting an array into hash in perl is easy to do with simple assignment like %hash =

Answer 1

If looking for a library you can use go-funk. This code may be less performant and not idiomatic in Go until we have Generics.

var elements = []string{"abc", "def", "fgi", "adi"}

elementsMap := funk.Map(
    funk.Chunk(elements, 2),
    func(x []string) (string, string) { // Slice to Map
        return x[0], x[1]
    },
)

fmt.Println(elementsMap) // map[abc:def fgi:adi]

https://play.golang.org/p/-t-33z4aKM_j

Answer 2

Use a for loop:

elements = []string{"abc", "def", "fgi", "adi"}
elementMap := make(map[string]string)
for i := 0; i < len(elements); i +=2 {
    elementMap[elements[i]] = elements[i+1]
}

runnable example on the playground

The standard library does not have a function to do this.

Answer 3

Try with range

elements := []string{"abc", "def", "fgi", "adi"}
    elementMap := make(map[int]string)
    for i, data := range elements  {
             elementMap[i] = data
        }

fmt.Println(elementMap ) // map[0:abc 1:def 2:fgi 3:adi]

https://play.golang.org/p/h6uZn5obLKg

Answer 4

There is currently no way to do it the perl way. You just have to iterate the slice, and place the slice elements in your map, e.g. as the map's key:

func main() {
    var elements []string
    var elementMap map[string]string
    elements = []string{"abc", "def", "fgi", "adi"}

    // initialize map
    elementMap = make(map[string]string)

    // put slice values into map
    for _, s := range elements {  
        elementMap[s] = s
        // or just keys, without values: elementMap[s] = ""
    }

    // print map
    for k := range elementMap {
        fmt.Println(k)
    }
}

Depending on what you want to do, you have to keep one thing in mind: map keys are unique, so if your slice contains duplicate strings you might want to keep count by using a map[string]int:

func main() {
    var elements []string
    var elementMap map[string]int
    elements = []string{"abc", "def", "fgi", "adi", "fgi", "adi"}

    // initialize map
    elementMap = make(map[string]int)

    // increment map's value for every key from slice
    for _, s := range elements {  
        elementMap[s]++
    }

    // print map
    for k, v := range elementMap {
        fmt.Println(k, v)
    }
}

And you can always wrap that functionality in a func:

func sliceToStrMap(elements []string) map[string]string {
    elementMap := make(map[string]string)
    for _, s := range elements {
        elementMap[s] = s
    }
    return elementMap
}

func sliceToIntMap(elements []string) map[string]int {
    elementMap := make(map[string]int)
    for _, s := range elements {
        elementMap[s]++
    }
    return elementMap
}