CODEWITHSUNDEEP
goslice
Nicky Feller
Nicky Feller

Reputation: 3929

Slice of slices with different types in golang

Context: I want to use the slice data structure in golang to make a 2-D feature vector. This feature vector should be a slice that consists of slices of different types, sometimes strings, int, float64 etc.

As of yet, I can achieve this with a map (below), is there a way to implement this with a slice?

map := make(map[int]interface{}}

What should be more like:

featureVector := []interface{[]int, []float64, []string ...}

Upvotes: 14

Views: 20632

Answers (1)

icza
icza

Reputation: 418435

It works as expected, you're just using wrong syntax. The element type of the slice is interface{}, so a composite literal to initialize it should look like []interface{}{ ... }, like in this example:

featureVector := []interface{}{[]int{1, 2}, []float64{1.2, 2.2}, []string{"a", "b"}}

And you can treat it like any other slice:

featureVector = append(featureVector, []byte{'x', 'y'})
fmt.Printf("%#v", featureVector)

Output (try it on the Go Playground):

[]interface{}{[]int{1, 2}, []float64{1.2, 2.2}, []string{"a", "b"}, []uint8{0x78, 0x79}}

But know that since the element type is interface{}, nothing prevents anybody to append a non-slice:

featureVector = append(featureVector, "abc") // OK

This also applies to the map solution.

Upvotes: 13

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