feat: add UniqueBy function in slice.go

slice/slice.go

@@ -582,6 +582,21 @@ func Unique[T any](slice []T) []T {
 	return res
 }
 
+// UniqueBy call iteratee func with every item of slice, then remove duplicated.
+func UniqueBy[T any](slice []T, iteratee func(item T) T) []T {
+	if len(slice) == 0 {
+		return []T{}
+	}
+
+	var res []T
+	for _, v := range slice {
+		val := iteratee(v)
+		res = append(res, val)
+	}
+
+	return Unique(res)
+}
+
 // Union creates a slice of unique values, in order, from all given slices. using == for equality comparisons.
 func Union[T any](slices ...[]T) []T {
 	if len(slices) == 0 {

slice/slice_test.go

@@ -395,6 +395,15 @@ func TestUnique(t *testing.T) {
 	assert.Equal([]string{"a", "b", "c"}, Unique([]string{"a", "a", "b", "c"}))
 }
 
+func TestUniqueBy(t *testing.T) {
+	assert := internal.NewAssert(t, "TestUniqueBy")
+
+	actual := UniqueBy([]int{1, 2, 3, 4, 5, 6}, func(val int) int {
+		return val % 4
+	})
+	assert.Equal([]int{1, 2, 3, 0}, actual)
+}
+
 func TestUnion(t *testing.T) {
 	assert := internal.NewAssert(t, "TestUnion")