A frequency map is just a fancy word for a hash map that tracks the number of occurrences of an element in a collection.
If we have a slice in go and we want to know exactly how many times each element in the slice occurs in the slice, we can build a frequency map out of it; then we can just hash the element as key in the map, and it should take O(1) to get the frequency.
A basic way to implement it can be:
type FrequencyMap[T comparable] struct {
kv map[T]int
}
func PopulateFrequencyMap[T comparable](elements []T) *FrequencyMap[T]{
fmap := &FrequencyMap[T]{
kv: make(map[T]int),
}
for _, element := range elements {
fmap.kv[element]++
}
return fmap
}
func (f *FrequencyMap[T]) Get(element T) int {
return f.kv[element]
}
func (f *FrequencyMap[T]) Add(element T) {
f.kv[element]++
}
func (f *FrequencyMap[T]) Remove(element T) {
if fq, ok := f.kv[element]; ok {
if fq <= 1 {
delete(f.kv, element)
return
}
f.kv[element]--
}
}
func (f *FrequencyMap[T]) MostFrequent() (element T, f int, ok bool) {
for k, v := range f.kv {
if v > f {
element = k
f = v
ok = true
}
}
return element, f, ok
}bye now.