sets — Unordered collections of unique elements

[Игорь Авдошкин]

Hi! 

Code python:

slice_int = [1,1,2,2,2,3,3]

slice_string = ["go", "go", "golang", "golang"]

print set(slice_int)

print set(slice_string)

Translate into Golang exists or built-in function?

[Matthew Holt]

Well, a set in Go is usually implemented as a map. Typically it's convenient for the value to be bool:

mySet := make(map[string]bool)

So to translate a slice to a map, something like this:

for _, val := range mySlice {

   mySet[val] = true

}

Should do the trick. This will not implement a "multi-set", though, so be aware that only unique elements will be admitted.

[Gyepi SAM]

You can use maps to represent sets

map[int]bool
map[string]bool

If you want to print sets differently from maps, type them and implement the
Stringer interface.

type IntSet map[int]bool
type StringSet map[string]bool

func (is IntSet) String() string {...}
...

-Gyepi

[Jason Del Ponte]

Recently I've been seeing code implement a set as
map[string]struck {}

Out of curiosity, is this better than a bool, or just different?

http://play.golang.org/p/S07WunT265

[Dan Kortschak]

Save one byte per entry since the value is not stored, just its presence
(which in this case is enough).

[Francesc Campoy Flores]

Implementing a multiset would be as easy as having map[string]int :-)

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Francesc Campoy

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[Dan Kortschak]

Yes, that's ho I do it unless there are additional attributes of the members that are not keyed on, in which case it's either map[T][]M or map[T]*[]M.

[Francesc Campoy Flores]

Then it's a multimap, not a multiset :-)

But yes, completely agreed.

[Dan Kortschak]

A rose by any other name..., or https://xkcd.com/1322/