feat: add FilterMap

slice/slice.go

@@ -421,6 +421,23 @@ func Map[T any, U any](slice []T, iteratee func(index int, item T) U) []U {
 	return result
 }
 
+// FilterMap returns a slice which apply both filtering and mapping to the given slice.
+// iteratee callback function should returntwo values:
+// 1, mapping result.
+// 2, whether the result element should be included or not
+// Play: todo
+func FilterMap[T any, U any](slice []T, iteratee func(index int, item T) (U, bool)) []U {
+	result := []U{}
+
+	for i, v := range slice {
+		if a, ok := iteratee(i, v); ok {
+			result = append(result, a)
+		}
+	}
+
+	return result
+}
+
 // Reduce creates an slice of values by running each element of slice thru iteratee function.
 // Play: https://go.dev/play/p/_RfXJJWIsIm
 func Reduce[T any](slice []T, iteratee func(index int, item1, item2 T) T, initial T) T {

slice/slice_example_test.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"math"
 	"reflect"
+	"strconv"
 )
 
 func ExampleContain() {
@@ -367,6 +368,24 @@ func ExampleMap() {
 	// [2 3 4]
 }
 
+func ExampleFilterMap() {
+	nums := []int{1, 2, 3, 4, 5}
+
+	getEvenNumStr := func(i, num int) (string, bool) {
+		if num%2 == 0 {
+			return strconv.FormatInt(int64(num), 10), true
+		}
+		return "", false
+	}
+
+	result := FilterMap(nums, getEvenNumStr)
+
+	fmt.Printf("%#v", result)
+
+	// Output:
+	// []string{"2", "4"}
+}
+
 func ExampleReduce() {
 	nums := []int{1, 2, 3}
 

slice/slice_test.go

@@ -3,6 +3,7 @@ package slice
 import (
 	"fmt"
 	"math"
+	"strconv"
 	"testing"
 
 	"github.com/duke-git/lancet/v2/internal"
@@ -315,6 +316,23 @@ func TestMap(t *testing.T) {
 	assert.Equal(studentsOfAdd10Aage, Map(students, mapFunc))
 }
 
+func TestFilterMap(t *testing.T) {
+	assert := internal.NewAssert(t, "TestFilterMap")
+
+	nums := []int{1, 2, 3, 4, 5}
+
+	getEvenNumStr := func(i, num int) (string, bool) {
+		if num%2 == 0 {
+			return strconv.FormatInt(int64(num), 10), true
+		}
+		return "", false
+	}
+
+	result := FilterMap(nums, getEvenNumStr)
+
+	assert.Equal([]string{"2", "4"}, result)
+}
+
 func TestReduce(t *testing.T) {
 	cases := [][]int{
 		{},