Set is a useful collection but there is no built-in implementation in Go lang.
The only one pkg which provides set operations now is golang-set
Unfortunately, the api of golang-set is not good enough.
For example, I want to generate a set from a int slice
import "github.com/deckarep/golang-set"
func main() {
ints := []int{1, 2, 3, 4}
mapset.NewSet(ints...)
mapset.NewSetFromSlice(ints)
mapset.NewSetWith(ints...)
}the code above can not work, according to
cannot use ints (type []int) as type []interface{}
You can not assign any slice to an []interface{} in Go lang.
So you need to copy your elements from []int to []interface by a loop.
That means you must do this manually every time you want to generate a set from slice.
It is ugly. So I create my own set
import "github.com/zoumo/goset"
func main() {
goset.NewSet(1, 2, 3, 4)
// or
goset.NewSetFrom([]int{1, 2, 3, 4})
goset.NewSet("1", "2", "3")
// or
goset.NewSetFrom([]string{"1", "2", "3"})
}Full API
// Set provides a collection of operations for sets
//
// The implementation of Set is base on hash table. So the elements must be
// hashable, functions, maps, slices are unhashable type, adding these elements
// will cause panic.
//
// There are two implementations of Set:
// 1. default is unsafe based on hash table(map)
// 2. thread safe based on sync.RWMutex
//
// The two kinds of sets can easily convert to the other one. But you must know
// exactly what you are doing to avoid the concurrent race
type Set interface {
SetToSlice
// Add adds all given elements to the set anyway, no matter if it whether already exists.
//
Add(elem ...interface{}) error
// Extend adds all elements in the given interface b to this set
// the given interface must be array, slice or Set.
Extend(b interface{}) error
// Remove deletes all given elements from the set.
Remove(elem ...interface{})
// Contains checks whether the given elem is in the set.
Contains(elem interface{}) bool
// ContainsAll checks whether all the given elems are in the set.
ContainsAll(elems ...interface{}) bool
ContainsAny(elems ...interface{}) bool
// Copy clones the set.
Copy() Set
// Len returns the size of set. aka Cardinality.
Len() int
// String returns the string representation of the set.
String() string
// Range calls f sequentially for each element present in the set.
// If f returns false, range stops the iteration.
//
// Note: the iteration order is not specified and is not guaranteed
// to be the same from one iteration to the next. The index only
// means how many elements have been visited in the iteration, it not
// specifies the index of an element in the set
Range(foreach func(index int, elem interface{}) bool)
// ---------------------------------------------------------------------
// Convert
// ToThreadUnsafe returns a thread unsafe set.
// Carefully use the method.
ToThreadUnsafe() Set
// ToThreadSafe returns a thread safe set.
// Carefully use the method.
ToThreadSafe() Set
// ---------------------------------------------------------------------
// Compare
// Equal checks whether this set is equal to the given one.
// There are two constraints if set a is equal to set b.
// the two set must have the same size and contain the same elements.
Equal(b Set) bool
// IsSubsetOf checks whether this set is the subset of the given set
// In other words, all elements in this set are also the elements
// of the given set.
IsSubsetOf(b Set) bool
// IsSupersetOf checks whether this set is the superset of the given set
// In other words, all elements in the given set are also the elements
// of this set.
IsSupersetOf(b Set) bool
// ---------------------------------------------------------------------
// Set Operations
// Diff returns the difference between the set and this given
// one, aka Difference Set
// math formula: a - b
Diff(b Set) Set
// SymmetricDiff returns the symmetric difference between this set
// and the given one. aka Symmetric Difference Set
// math formula: (a - b) ∪ (b - a)
SymmetricDiff(b Set) Set
// Unite combines two sets into a new one, aka Union Set
// math formula: a ∪ b
Unite(b Set) Set
// Intersect returns the intersection of two set, aka Intersection Set
// math formula: a ∩ b
Intersect(b Set) Set
}
// SetToSlice contains methods that knows how to convert set to slice.
type SetToSlice interface {
// ToStrings returns all string elements in this set.
ToStrings() []string
// ToInts returns all int elements in this set.
ToInts() []int
// Elements returns all elements in this set.
Elements() []interface{}
}