Go determine number of word occurences on a string slice - dictionary

Question

Having a hard time trying to figure out how can I count the number of apps or words on a slice using the go-lang code I made.
Hoping someone could help me figure out how to count the number of occurence?
https://play.golang.org/p/KvgI-lCz_c6
package main
import (
"fmt"
)
func main() {
apps := []string{"one", "two", "three", "one", "four"}
fmt.Println("apps:", apps)
o := CountOccurence(apps)
fmt.Println("=== o: ", o)
}
func CountOccurence(apps []string) map[string]int {
dict := make(map[string]int)
for k, v := range apps {
fmt.Println(k, v)
dict[v] = k
}
// fmt.Println("=== dict: ", dict)
return dict
}
Outputs the following
apps: [one two three one four]
0 one
1 two
2 three
3 one
4 four
=== o: map[four:4 one:3 three:2 two:1]
PS: go strings.Count only counts a string, not a []string.

Answer 1

What you currently do is you gather the different elements and you assign their index to them. If a word occurs multiple times, the highest index will be assigned to it.
As you stated, you want to count the words. So instead of the index, assign 1 for new words (first occurrence), and if it's already in the map, increment its value by 1.
Since you can index a map with a non-existing key, in which case the result is the zero value of the value type of the map, which is 0 for int, it will tell you it was found 0 times (so far), so you don't even have to check if a key is already in there, just go ahead and increment it:
dict[v]++
So CountOccurrences() may look like this:
func CountOccurence(apps []string) map[string]int {
dict := make(map[string]int)
for _, v := range apps {
fmt.Println(v)
dict[v]++
}
return dict
}
Which will output (try it on the Go Playground):
apps: [one two three one four]
one
two
three
one
four
=== o: map[four:1 one:2 three:1 two:1]