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|
package set
import (
"sort"
"strings"
)
// Set implements basic string set operations, not thread-safe.
type Set map[string]struct{}
// New creates a new set.
func New() Set {
var s = make(Set)
return s
}
// FromSlice initializes a set from a slice.
func FromSlice(vs []string) Set {
s := New()
for _, v := range vs {
s.Add(v)
}
return s
}
// Clear removes all elements.
func (s Set) Clear() {
for k := range s {
delete(s, k)
}
}
// Add adds an element.
func (s Set) Add(v string) Set {
s[v] = struct{}{}
return s
}
// Len returns number of elements in set.
func (s Set) Len() int {
return len(s)
}
// IsEmpty returns if set has zero elements.
func (s Set) IsEmpty() bool {
return s.Len() == 0
}
// Equals returns true, if sets contain the same elements.
func (s Set) Equals(t Set) bool {
for k := range s {
if !t.Contains(k) {
return false
}
}
return s.Len() == t.Len()
}
// Contains returns membership status.
func (s Set) Contains(v string) bool {
_, ok := (s)[v]
return ok
}
// Intersection returns a new set containing all elements found in both sets.
func (s Set) Intersection(t Set) Set {
u := New()
for k := range s {
if t.Contains(k) {
u.Add(k)
}
}
return u
}
// Union returns the union of two sets.
func (s Set) Union(t Set) Set {
u := New()
for k := range s {
u.Add(k)
}
for k := range t {
u.Add(k)
}
return u
}
// Slice returns all elements as a slice.
func (s Set) Slice() (result []string) {
for k := range s {
result = append(result, k)
}
return
}
// Sorted returns all elements as a slice, sorted.
func (s Set) Sorted() (result []string) {
for k := range s {
result = append(result, k)
}
sort.Strings(result)
return
}
// TopK returns at most k sorted elements.
func (s Set) TopK(k int) Set {
var top []string
for i, v := range s.Sorted() {
if i < k {
top = append(top, v)
}
}
return FromSlice(top)
}
// Product returns a slice of pairs, representing the cartesian product of two sets.
func (s Set) Product(t Set) (result [][]string) {
for k := range s {
for l := range t {
result = append(result, []string{k, l})
}
}
return
}
// Jaccard returns the jaccard index of sets s and t, between 0 and 1, where 1
// means equality.
func (s Set) Jaccard(t Set) float64 {
if s.IsEmpty() && t.IsEmpty() {
return 1
}
if u := s.Union(t); u.IsEmpty() {
return 0
} else {
return float64(s.Intersection(t).Len()) / float64(u.Len())
}
}
// Join joins elements from a set with given separator.
func (s Set) Join(sep string) string {
return strings.Join(s.Slice(), sep)
}
// Max returns the size of the largest set.
func Max(ss ...Set) (max int) {
for _, s := range ss {
if s.Len() > max {
max = s.Len()
}
}
return
}
// Min returns the size of the smallest set.
func Min(ss ...Set) (min int) {
min = 2 << 30
for _, s := range ss {
if s.Len() < min {
min = s.Len()
}
}
return
}
// Filter returns a set containing all elements, which satisfy a given predicate.
func Filter(s Set, f func(string) bool) Set {
t := New()
for v := range s {
if f(v) {
t.Add(v)
}
}
return t
}
|
