Golang : How to count duplicate items in slice/array?
Problem :
You need to count the number of duplicate items in a slice or array.
Solution :
Pseudo-code : Create a map and insert one item from the slice/array with a for loop. Before inserting a new item check if a similar item already exist in the map. If yes, increase the counter value associated with the particular item and if no, assign a new counter with the value of 1 for the new item(in the map).
Here you go :
package main
import (
"fmt"
)
func printslice(slice []string) {
fmt.Println("slice = ", slice)
}
func dup_count(list []string) map[string]int {
duplicate_frequency := make(map[string]int)
for _, item := range list {
// check if the item/element exist in the duplicate_frequency map
_, exist := duplicate_frequency[item]
if exist {
duplicate_frequency[item] += 1 // increase counter by 1 if already in the map
} else {
duplicate_frequency[item] = 1 // else start counting from 1
}
}
return duplicate_frequency
}
func main() {
duplicate := []string{"Hello", "World", "GoodBye", "World", "We", "Love", "Love", "You"}
printslice(duplicate)
dup_map := dup_count(duplicate)
//fmt.Println(dup_map)
for k, v := range dup_map {
fmt.Printf("Item : %s , Count : %d\n", k, v)
}
}
Sample output :
slice = [Hello World GoodBye World We Love Love You]
Item : You , Count : 1
Item : Hello , Count : 1
Item : World , Count : 2
Item : GoodBye , Count : 1
Item : We , Count : 1
Item : Love , Count : 2
See also : Golang : Delete duplicate items from a slice/array
By Adam Ng
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