Groups elements from a source based on a key selection function.
func GroupBy[T any](keySelector KeySelector[T], source any, dest any) *Builder[T]
- Description: Groups elements from source based on the key returned by keySelector and stores them in dest.
- Parameters:
- keySelector: Function that extracts a key from each element of type T. It takes an element of type T and returns a key of type any.
- source: Source data to group (expects pointers to slices or maps). dest: Destination where grouped elements will be stored (expects pointers to maps).
Example
1package main
2
3import (
4 "fmt"
5
6 collection "github.com/jose78/go-collection/v2"
7)
8
9type Person struct {
10 Name string
11 Age int
12}
13
14func keySelectorByAge(person Person) any {
15 return person.Age
16}
17
18func main() {
19 people := []Person{
20 {"Alice", 25},
21 {"Bob", 30},
22 {"Charlie", 25},
23 }
24
25 groups := make(map[int][]Person)
26
27 builderError := collection.GroupBy(keySelectorByAge, people, groups)
28
29 if builderError != nil {
30 fmt.Printf("Error during grouping: %v\n", builderError.Error())
31 } else {
32 for age, group := range groups {
33 fmt.Printf("People with age %d:\n", age)
34 for _, person := range group {
35 fmt.Printf("- %s\n", person.Name)
36 }
37 }
38 }
39
40}