# Slice Package slice implements some functions to manipulate slice.
## Source: - [https://github.com/duke-git/lancet/blob/main/slice/slice.go](https://github.com/duke-git/lancet/blob/main/slice/slice.go) - [https://github.com/duke-git/lancet/blob/main/slice/slice_concurrent.go](https://github.com/duke-git/lancet/blob/main/slice/slice_concurrent.go)
## Usage: ```go import ( "github.com/duke-git/lancet/v2/slice" ) ```
## Index - [AppendIfAbsent](#AppendIfAbsent) - [Contain](#Contain) - [ContainBy](#ContainBy) - [ContainSubSlice](#ContainSubSlice) - [Chunk](#Chunk) - [Compact](#Compact) - [Concat](#Concat) - [Count](#Count) - [CountBy](#CountBy) - [Difference](#Difference) - [DifferenceBy](#DifferenceBy) - [DifferenceWith](#DifferenceWith) - [DeleteAt](#DeleteAt) - [DeleteRange](#DeleteRange) - [Drop](#Drop) - [DropRight](#DropRight) - [DropWhile](#DropWhile) - [DropRightWhile](#DropRightWhile) - [Equal](#Equal) - [EqualWith](#EqualWith) - [Every](#Every) - [Filter](#Filter) - [FilterConcurrent](#FilterConcurrent) - [Finddeprecated](#Find) - [FindBy](#FindBy) - [FindLastdeprecated](#FindLast) - [FindLastBy](#FindLastBy) - [Flatten](#Flatten) - [FlattenDeep](#FlattenDeep) - [ForEach](#ForEach) - [ForEachConcurrent](#ForEachConcurrent) - [ForEachWithBreak](#ForEachWithBreak) - [GroupBy](#GroupBy) - [GroupWith](#GroupWith) - [IntSlicedeprecated](#IntSlice) - [InterfaceSlicedeprecated](#InterfaceSlice) - [Intersection](#Intersection) - [InsertAt](#InsertAt) - [IndexOf](#IndexOf) - [LastIndexOf](#LastIndexOf) - [Map](#Map) - [MapConcurrent](#MapConcurrent) - [FilterMap](#FilterMap) - [FlatMap](#FlatMap) - [Merge](#Merge) - [Reverse](#Reverse) - [Reducedeprecated](#Reduce) - [ReduceConcurrent](#ReduceConcurrent) - [ReduceBy](#ReduceBy) - [ReduceRight](#ReduceRight) - [Replace](#Replace) - [ReplaceAll](#ReplaceAll) - [Repeat](#Repeat) - [Shuffle](#Shuffle) - [IsAscending](#IsAscending) - [IsDescending](#IsDescending) - [IsSorted](#IsSorted) - [IsSortedByKey](#IsSortedByKey) - [Sort](#Sort) - [SortBy](#SortBy) - [SortByField](#SortByField) - [Some](#Some) - [StringSlicedeprecated](#StringSlice) - [SymmetricDifference](#SymmetricDifference) - [ToSlice](#ToSlice) - [ToSlicePointer](#ToSlicePointer) - [Unique](#Unique) - [UniqueBy](#UniqueBy) - [UniqueByComparator](#UniqueByComparator) - [UniqueByField](#UniqueByField) - [UniqueByConcurrent](#UniqueByConcurrent) - [Union](#Union) - [UnionBy](#UnionBy) - [UpdateAt](#UpdateAt) - [Without](#Without) - [KeyBy](#KeyBy) - [Join](#Join) - [Partition](#Partition) - [SetToDefaultIf](#SetToDefaultIf) - [Break](#Break) - [RightPadding](#RightPadding) - [LeftPadding](#LeftPadding) - [Frequency](#Frequency) - [JoinFunc](#JoinFunc) - [ConcatBy](#ConcatBy)
## Documentation ### AppendIfAbsent

If slice doesn't contain the item, append it to the slice.

Signature: ```go func AppendIfAbsent[T comparable](slice []T, item T) []T ``` Example:[Run](https://go.dev/play/p/GNdv7Jg2Taj) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result1 := slice.AppendIfAbsent([]string{"a", "b"}, "b") result2 := slice.AppendIfAbsent([]string{"a", "b"}, "c") fmt.Println(result1) fmt.Println(result2) // Output: // [a b] // [a b c] } ``` ### Contain

Check if the target value is in the slice or not.

Signature: ```go func Contain[T comparable](slice []T, target T) bool ``` Example:[Run](https://go.dev/play/p/_454yEHcNjf) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result1 := slice.Contain([]string{"a", "b", "c"}, "a") result2 := slice.Contain([]int{1, 2, 3}, 4) fmt.Println(result1) fmt.Println(result2) // Output: // true // false } ``` ### ContainBy

returns true if predicate function return true.

Signature: ```go func ContainBy[T any](slice []T, predicate func(item T) bool) bool ``` Example:[Run](https://go.dev/play/p/49tkHfX4GNc) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { type foo struct { A string B int } array1 := []foo{{A: "1", B: 1}, {A: "2", B: 2}} result1 := slice.ContainBy(array1, func(f foo) bool { return f.A == "1" && f.B == 1 }) result2 := slice.ContainBy(array1, func(f foo) bool { return f.A == "2" && f.B == 1 }) array2 := []string{"a", "b", "c"} result3 := slice.ContainBy(array2, func(t string) bool { return t == "a" }) result4 := slice.ContainBy(array2, func(t string) bool { return t == "d" }) fmt.Println(result1) fmt.Println(result2) fmt.Println(result3) fmt.Println(result4) // Output: // true // false // true // false } ``` ### ContainSubSlice

Check if the slice contain subslice or not.

Signature: ```go func ContainSubSlice[T comparable](slice, subSlice []T) bool ``` Example:[Run](https://go.dev/play/p/bcuQ3UT6Sev) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result1 := slice.ContainSubSlice([]string{"a", "b", "c"}, []string{"a", "b"}) result2 := slice.ContainSubSlice([]string{"a", "b", "c"}, []string{"a", "d"}) fmt.Println(result1) fmt.Println(result2) // Output: // true // false } ``` ### Chunk

Creates an slice of elements split into groups the length of `size`.

Signature: ```go func Chunk[T any](slice []T, size int) [][]T ``` Example:[Run](https://go.dev/play/p/b4Pou5j2L_C) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { arr := []string{"a", "b", "c", "d", "e"} result1 := slice.Chunk(arr, 1) result2 := slice.Chunk(arr, 2) result3 := slice.Chunk(arr, 3) result4 := slice.Chunk(arr, 4) result5 := slice.Chunk(arr, 5) fmt.Println(result1) fmt.Println(result2) fmt.Println(result3) fmt.Println(result4) fmt.Println(result5) // Output: // [[a] [b] [c] [d] [e]] // [[a b] [c d] [e]] // [[a b c] [d e]] // [[a b c d] [e]] // [[a b c d e]] } ``` ### Compact

Creates an slice with all falsey values removed. The values false, nil, 0, and "" are falsey.

Signature: ```go func Compact[T comparable](slice []T) []T ``` Example:[Run](https://go.dev/play/p/pO5AnxEr3TK) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result1 := slice.Compact([]int{0}) result2 := slice.Compact([]int{0, 1, 2, 3}) result3 := slice.Compact([]string{"", "a", "b", "0"}) result4 := slice.Compact([]bool{false, true, true}) fmt.Println(result1) fmt.Println(result2) fmt.Println(result3) fmt.Println(result4) // Output: // [] // [1 2 3] // [a b 0] // [true true] } ``` ### Concat

Concat creates a new slice concatenating slice with any additional slices.

Signature: ```go func Concat[T any](slices ...[]T) []T ``` Example:[Run](https://go.dev/play/p/gPt-q7zr5mk) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result1 := slice.Concat([]int{1, 2}, []int{3, 4}) result2 := slice.Concat([]string{"a", "b"}, []string{"c"}, []string{"d"}) fmt.Println(result1) fmt.Println(result2) // Output: // [1 2 3 4] // [a b c d] } ``` ### Count

Returns the number of occurrences of the given item in the slice.

Signature: ```go func Count[T comparable](slice []T, item T) int ``` Example:[Run](https://go.dev/play/p/Mj4oiEnQvRJ) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 3, 4} result1 := slice.Count(nums, 1) result2 := slice.Count(nums, 3) fmt.Println(result1) fmt.Println(result2) // Output: // 1 // 2 } ``` ### CountBy

Iterates over elements of slice with predicate function, returns the number of all matched elements.

Signature: ```go func CountBy[T any](slice []T, predicate func(index int, item T) bool) int ``` Example:[Run](https://go.dev/play/p/tHOccTMDZCC) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4, 5} isEven := func(i, num int) bool { return num%2 == 0 } result := slice.CountBy(nums, isEven) fmt.Println(result) // Output: // 2 } ``` ### Difference

Creates an slice of whose element not included in the other given slice.

Signature: ```go func Difference[T comparable](slice, comparedSlice []T) []T ``` Example:[Run](https://go.dev/play/p/VXvadzLzhDa) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { s1 := []int{1, 2, 3, 4, 5} s2 := []int{4, 5, 6} result := slice.Difference(s1, s2) fmt.Println(result) // Output: // [1 2 3] } ``` ### DifferenceBy

DifferenceBy accepts iteratee func which is invoked for each element of slice and values to generate the criterion by which they're compared.

Signature: ```go func DifferenceBy[T comparable](slice []T, comparedSlice []T, iteratee func(index int, item T) T) []T ``` Example:[Run](https://go.dev/play/p/DiivgwM5OnC) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { s1 := []int{1, 2, 3, 4, 5} s2 := []int{3, 4, 5} addOne := func(i int, v int) int { return v + 1 } result := slice.DifferenceBy(s1, s2, addOne) fmt.Println(result) // Output: // [1 2] } ``` ### DifferenceWith

DifferenceWith accepts comparator which is invoked to compare elements of slice to values. The order and references of result values are determined by the first slice.

Signature: ```go func DifferenceWith[T any](slice []T, comparedSlice []T, comparator func(value, otherValue T) bool) []T ``` Example:[Run](https://go.dev/play/p/v2U2deugKuV) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { s1 := []int{1, 2, 3, 4, 5} s2 := []int{4, 5, 6, 7, 8} isDouble := func(v1, v2 int) bool { return v2 == 2*v1 } result := slice.DifferenceWith(s1, s2, isDouble) fmt.Println(result) // Output: // [1 5] } ``` ### DeleteAt

Delete delete the element of slice at index.

Signature: ```go func DeleteAt[T any](slice []T, index int) ``` Example:[Run](https://go.dev/play/p/800B1dPBYyd) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { chars := []string{"a", "b", "c", "d", "e"} result1 := slice.DeleteAt(chars, 0) result2 := slice.DeleteAt(chars, 4) result3 := slice.DeleteAt(chars, 5) result4 := slice.DeleteAt(chars, 6) fmt.Println(result1) fmt.Println(result2) fmt.Println(result3) fmt.Println(result4) // Output: // [b c d e] // [a b c d] // [a b c d] // [a b c d] } ``` ### DeleteRange

Delete the element of slice from start index to end index（exclude)

Signature: ```go func DeleteRange[T any](slice []T, start, end int) []T ``` Example:[Run](https://go.dev/play/p/945HwiNrnle) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { chars := []string{"a", "b", "c", "d", "e"} result1 := slice.DeleteRange(chars, 0, 0) result2 := slice.DeleteRange(chars, 0, 1) result3 := slice.DeleteRange(chars, 0, 3) result4 := slice.DeleteRange(chars, 0, 4) result5 := slice.DeleteRange(chars, 0, 5) fmt.Println(result1) fmt.Println(result2) fmt.Println(result3) fmt.Println(result4) fmt.Println(result5) // Output: // [a b c d e] // [b c d e] // [d e] // [e] // [] } ``` ### Drop

Drop n elements from the start of a slice.

Signature: ```go func Drop[T any](slice []T, n int) []T ``` Example:[Run](https://go.dev/play/p/jnPO2yQsT8H) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result1 := slice.Drop([]string{"a", "b", "c"}, 0) result2 := slice.Drop([]string{"a", "b", "c"}, 1) result3 := slice.Drop([]string{"a", "b", "c"}, -1) result4 := slice.Drop([]string{"a", "b", "c"}, 4) fmt.Println(result1) fmt.Println(result2) fmt.Println(result3) fmt.Println(result4) // Output: // [a b c] // [b c] // [a b c] // [] } ``` ### DropRight

Drop n elements from the end of a slice.

Signature: ```go func DropRight[T any](slice []T, n int) []T ``` Example:[Run](https://go.dev/play/p/8bcXvywZezG) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result1 := slice.DropRight([]string{"a", "b", "c"}, 0) result2 := slice.DropRight([]string{"a", "b", "c"}, 1) result3 := slice.DropRight([]string{"a", "b", "c"}, -1) result4 := slice.DropRight([]string{"a", "b", "c"}, 4) fmt.Println(result1) fmt.Println(result2) fmt.Println(result3) fmt.Println(result4) // Output: // [a b c] // [a b] // [a b c] // [] } ``` ### DropWhile

Drop n elements from the start of a slice while predicate function returns true.

Signature: ```go func DropWhile[T any](slice []T, predicate func(item T) bool) []T ``` Example:[Run](https://go.dev/play/p/4rt252UV_qs) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result1 := slice.DropWhile(numbers, func(n int) bool { return n != 2 }) result2 := slice.DropWhile(numbers, func(n int) bool { return true }) result3 := slice.DropWhile(numbers, func(n int) bool { return n == 0 }) fmt.Println(result1) fmt.Println(result2) fmt.Println(result3) // Output: // [2 3 4 5] // [] // [1 2 3 4 5] } ``` ### DropRightWhile

Drop n elements from the end of a slice while predicate function returns true.

Signature: ```go func DropRightWhile[T any](slice []T, predicate func(item T) bool) []T ``` Example:[Run](https://go.dev/play/p/6wyK3zMY56e) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { numbers := []int{1, 2, 3, 4, 5} result1 := slice.DropRightWhile(numbers, func(n int) bool { return n != 2 }) result2 := slice.DropRightWhile(numbers, func(n int) bool { return true }) result3 := slice.DropRightWhile(numbers, func(n int) bool { return n == 0 }) fmt.Println(result1) fmt.Println(result2) fmt.Println(result3) // Output: // [1 2] // [] // [1 2 3 4 5] } ``` ### Equal

Check if two slices are equal: the same length and all elements' order and value are equal.

Signature: ```go func Equal[T comparable](slice1, slice2 []T) bool ``` Example:[Run](https://go.dev/play/p/WcRQJ37ifPa) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { s1 := []int{1, 2, 3} s2 := []int{1, 2, 3} s3 := []int{1, 3, 2} result1 := slice.Equal(s1, s2) result2 := slice.Equal(s1, s3) fmt.Println(result1) fmt.Println(result2) // Output: // true // false } ``` ### EqualWith

Check if two slices are equal with comparator func.

Signature: ```go func EqualWith[T, U any](slice1 []T, slice2 []U, comparator func(T, U) bool) bool ``` Example:[Run](https://go.dev/play/p/b9iygtgsHI1) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { s1 := []int{1, 2, 3} s2 := []int{2, 4, 6} isDouble := func(a, b int) bool { return b == a*2 } result := slice.EqualWith(s1, s2, isDouble) fmt.Println(result) // Output: // true } ``` ### Every

Return true if all of the values in the slice pass the predicate function.

Signature: ```go func Every[T any](slice []T, predicate func(index int, item T) bool) bool ``` Example:[Run](https://go.dev/play/p/R8U6Sl-j8cD) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 5} isEven := func(i, num int) bool { return num%2 == 0 } result := slice.Every(nums, isEven) fmt.Println(result) // Output: // false } ``` ### Filter

Return all elements which match the function.

Signature: ```go func Filter[T any](slice []T, predicate func(index int, item T) bool) []T ``` Example:[Run](https://go.dev/play/p/SdPna-7qK4T) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4, 5} isEven := func(i, num int) bool { return num%2 == 0 } result := slice.Filter(nums, isEven) fmt.Println(result) // Output: // [2 4] } ``` ### FilterConcurrent

Applies the provided filter function `predicate` to each element of the input slice concurrently.

Signature: ```go func FilterConcurrent[T any](slice []T, predicate func(index int, item T) bool, numThreads int) []T ``` Example:[Run](https://go.dev/play/p/t_pkwerIRVx) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4, 5} isEven := func(i, num int) bool { return num%2 == 0 } result := slice.FilterConcurrent(nums, isEven, 2) fmt.Println(result) // Output: // [2 4] } ``` ### Find

Iterates over elements of slice, returning the first one that passes a truth test on function.

> ⚠️ This function is deprecated. use `FindBy` instead. Signature: ```go func Find[T any](slice []T, predicate func(index int, item T) bool) (*T, bool) ``` Example:[Run](https://go.dev/play/p/CBKeBoHVLgq) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4, 5} isEven := func(i, num int) bool { return num%2 == 0 } result, ok := slice.Find(nums, isEven) fmt.Println(*result) fmt.Println(ok) // Output: // 2 // true } ``` ### FindBy

Iterates over elements of slice, returning the first one that passes a truth test on predicate function.If return T is nil or zero value then no items matched the predicate func. In contrast to Find or FindLast, its return value no longer requires dereferencing.

Signature: ```go func FindBy[T any](slice []T, predicate func(index int, item T) bool) (v T, ok bool) ``` Example:[Run](https://go.dev/play/p/n1lysBYl-GB) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4, 5} isEven := func(i, num int) bool { return num%2 == 0 } result, ok := slice.FindBy(nums, isEven) fmt.Println(result) fmt.Println(ok) // Output: // 2 // true } ``` ### FindLast

iterates over elements of slice from end to begin, returning the last one that passes a truth test on function.

> ⚠️ This function is deprecated. use `FindLastBy` instead. Signature: ```go func FindLast[T any](slice []T, predicate func(index int, item T) bool) (*T, bool) ``` Example:[Run](https://go.dev/play/p/FFDPV_j7URd) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4, 5} isEven := func(i, num int) bool { return num%2 == 0 } result, ok := slice.FindLast(nums, isEven) fmt.Println(*result) fmt.Println(ok) // Output: // 4 // true } ``` ### FindLastBy

FindLastBy iterates over elements of slice, returning the last one that passes a truth test on predicate function. If return T is nil or zero value then no items matched the predicate func. In contrast to Find or FindLast, its return value no longer requires dereferencing.

Signature: ```go func FindLastBy[T any](slice []T, predicate func(index int, item T) bool) (v T, ok bool) ``` Example:[Run](https://go.dev/play/p/8iqomzyCl_s) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4, 5} isEven := func(i, num int) bool { return num%2 == 0 } result, ok := slice.FindLastBy(nums, isEven) fmt.Println(result) fmt.Println(ok) // Output: // 4 // true } ``` ### Flatten

Flatten slice with one level.

Signature: ```go func Flatten(slice any) any ``` Example:[Run](https://go.dev/play/p/hYa3cBEevtm) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { arrs := [][][]string{{{"a", "b"}}, {{"c", "d"}}} result := slice.Flatten(arrs) fmt.Println(result) // Output: // [[a b] [c d]] } ``` ### FlattenDeep

flattens slice recursive.

Signature: ```go func FlattenDeep(slice any) any ``` Example:[Run](https://go.dev/play/p/yjYNHPyCFaF) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { arrs := [][][]string{{{"a", "b"}}, {{"c", "d"}}} result := slice.FlattenDeep(arrs) fmt.Println(result) // Output: // [a b c d] } ``` ### ForEach

Iterates over elements of slice and invokes function for each element.

Signature: ```go func ForEach[T any](slice []T, iteratee func(index int, item T)) ``` Example:[Run](https://go.dev/play/p/DrPaa4YsHRF) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3} var result []int addOne := func(_ int, v int) { result = append(result, v+1) } slice.ForEach(nums, addOne) fmt.Println(result) // Output: // [2 3 4] } ``` ### ForEachConcurrent

Applies the iteratee function to each item in the slice concurrently.

Signature: ```go func ForEachConcurrent[T any](slice []T, iteratee func(index int, item T), numThreads int) ``` Example:[Run](https://go.dev/play/p/kT4XW7DKVoV) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4, 5, 6, 7, 8} result := make([]int, len(nums)) addOne := func(index int, value int) { result[index] = value + 1 } slice.ForEachConcurrent(nums, addOne, 4) fmt.Println(result) // Output: // [2 3 4 5 6 7 8 9] } ``` ### ForEachWithBreak

Iterates over elements of slice and invokes function for each element, when iteratee return false, will break the for each loop.

Signature: ```go func ForEachWithBreak[T any](slice []T, iteratee func(index int, item T) bool) ``` Example:[Run](https://go.dev/play/p/qScs39f3D9W) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { numbers := []int{1, 2, 3, 4, 5} var sum int slice.ForEachWithBreak(numbers, func(_, n int) bool { if n > 3 { return false } sum += n return true }) fmt.Println(sum) // Output: // 6 } ``` ### GroupBy

Iterates over elements of the slice, each element will be group by criteria, returns two slices.

Signature: ```go func GroupBy[T any](slice []T, groupFn func(index int, item T) bool) ([]T, []T) ``` Example:[Run](https://go.dev/play/p/QVkPxzPR0iA) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4, 5} isEven := func(i, num int) bool { return num%2 == 0 } even, odd := slice.GroupBy(nums, isEven) fmt.Println(even) fmt.Println(odd) // Output: // [2 4] // [1 3 5] } ``` ### GroupWith

Return a map composed of keys generated from the results of running each element of slice thru iteratee.

Signature: ```go func GroupWith[T any, U comparable](slice []T, iteratee func(T) U) map[U][]T ``` Example:[Run](https://go.dev/play/p/ApCvMNTLO8a) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []float64{6.1, 4.2, 6.3} floor := func(num float64) float64 { return math.Floor(num) } result := slice.GroupWith(nums, floor) //map[float64][]float64 fmt.Println(result) // Output: // map[4:[4.2] 6:[6.1 6.3]] } ``` ### IntSlice

Convert interface slice to int slice.

> ⚠️ This function is deprecated. Use generic feature of go1.18+ for replacement. Signature: ```go func IntSlice(slice any) []int ``` Example:[Run](https://go.dev/play/p/UQDj-on9TGN) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []interface{}{1, 2, 3} result := slice.IntSlice(nums) //[]int{1, 2, 3} fmt.Println(result) // Output: // [1 2 3] } ``` ### InterfaceSlice

Convert value to interface slice.

> ⚠️ This function is deprecated. Use generic feature of go1.18+ for replacement. Signature: ```go func InterfaceSlice(slice any) []any ``` Example:[Run](https://go.dev/play/p/FdQXF0Vvqs-) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { strs := []string{"a", "b", "c"} result := slice.InterfaceSlice(strs) //[]interface{}{"a", "b", "c"} fmt.Println(result) // Output: // [a b c] } ``` ### Intersection

Creates a slice of unique values that included by all slices.

Signature: ```go func Intersection[T comparable](slices ...[]T) []T ``` Example:[Run](https://go.dev/play/p/anJXfB5wq_t) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums1 := []int{1, 2, 3} nums2 := []int{2, 3, 4} result := slice.Intersection(nums1, nums2) fmt.Println(result) // Output: // [2 3] } ``` ### InsertAt

insert the element into slice at index.

Signature: ```go func InsertAt[T any](slice []T, index int, value any) []T ``` Example:[Run](https://go.dev/play/p/hMLNxPEGJVE) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result1 := slice.InsertAt([]string{"a", "b", "c"}, 0, "1") result2 := slice.InsertAt([]string{"a", "b", "c"}, 1, "1") result3 := slice.InsertAt([]string{"a", "b", "c"}, 2, "1") result4 := slice.InsertAt([]string{"a", "b", "c"}, 3, "1") result5 := slice.InsertAt([]string{"a", "b", "c"}, 0, []string{"1", "2", "3"}) fmt.Println(result1) fmt.Println(result2) fmt.Println(result3) fmt.Println(result4) fmt.Println(result5) // Output: // [1 a b c] // [a 1 b c] // [a b 1 c] // [a b c 1] // [1 2 3 a b c] } ``` ### IndexOf

Returns the index at which the first occurrence of a item is found in a slice or return -1 if the item cannot be found.

Signature: ```go func IndexOf[T comparable](slice []T, item T) int ``` Example:[Run](https://go.dev/play/p/MRN1f0FpABb) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { strs := []string{"a", "a", "b", "c"} result1 := slice.IndexOf(strs, "a") result2 := slice.IndexOf(strs, "d") fmt.Println(result1) fmt.Println(result2) // Output: // 0 // -1 } ``` ### LastIndexOf

Returns the index at which the last occurrence of a item is found in a slice or return -1 if the item cannot be found.

Signature: ```go func LastIndexOf[T comparable](slice []T, item T) int ``` Example:[Run](https://go.dev/play/p/DokM4cf1IKH) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { strs := []string{"a", "a", "b", "c"} result1 := slice.LastIndexOf(strs, "a") result2 := slice.LastIndexOf(strs, "d") fmt.Println(result1) fmt.Println(result2) // Output: // 1 // -1 } ``` ### Map

Creates an slice of values by running each element in slice thru function.

Signature: ```go func Map[T any, U any](slice []T, iteratee func(index int, item T) U) []U ``` Example:[Run](https://go.dev/play/p/biaTefqPquw) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3} addOne := func(_ int, v int) int { return v + 1 } result := slice.Map(nums, addOne) fmt.Println(result) // Output: // [2 3 4] } ``` ### MapConcurrent

Applies the iteratee function to each item in the slice by concrrent.

Signature: ```go func MapConcurrent[T any, U any](slice []T, iteratee func(index int, item T) U, numThreads int) []U ``` Example:[Run](https://go.dev/play/p/H1ehfPkPen0) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4, 5, 6} result := slice.MapConcurrent(nums, func(_, n int) int { return n * n }, 4) fmt.Println(result) // Output: // [1 4 9 16 25 36] } ``` ### 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.

Signature: ```go func FilterMap[T any, U any](slice []T, iteratee func(index int, item T) (U, bool)) []U ``` Example:[Run](https://go.dev/play/p/J94SZ_9MiIe) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { 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 := slice.FilterMap(nums, getEvenNumStr) fmt.Printf("%#v", result) // Output: // []string{"2", "4"} } ``` ### FlatMap

Manipulates a slice and transforms and flattens it to a slice of another type.

Signature: ```go func FlatMap[T any, U any](slice []T, iteratee func(index int, item T) []U) []U ``` Example:[Run](https://go.dev/play/p/_QARWlWs1N_F) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4} result := slice.FlatMap(nums, func(i int, num int) []string { s := "hi-" + strconv.FormatInt(int64(num), 10) return []string{s} }) fmt.Printf("%#v", result) // Output: // []string{"hi-1", "hi-2", "hi-3", "hi-4"} } ``` ### Merge

Merge all given slices into one slice.

> ⚠️ This function is deprecated. use `Concat` instead. Signature: ```go func Merge[T any](slices ...[]T) []T ``` Example:[Run](https://go.dev/play/p/lbjFp784r9N) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums1 := []int{1, 2, 3} nums2 := []int{3, 4} result := slice.Merge(nums1, nums2) fmt.Println(result) // Output: // [1 2 3 3 4] } ``` ### Reverse

Reverse the elements order in slice.

Signature: ```go func Reverse[T any](slice []T) ``` Example:[Run](https://go.dev/play/p/8uI8f1lwNrQ) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { strs := []string{"a", "b", "c", "d"} slice.Reverse(strs) fmt.Println(strs) // Output: // [d c b a] } ``` ### Reduce

Reduce slice.

> ⚠️ This function is deprecated. use `ReduceBy` instead. Signature: ```go func Reduce[T any](slice []T, iteratee func(index int, item1, item2 T) T, initial T) T ``` Example:[Run](https://go.dev/play/p/_RfXJJWIsIm) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3} sum := func(_ int, v1, v2 int) int { return v1 + v2 } result := slice.Reduce(nums, sum, 0) fmt.Println(result) // Output: // 6 } ``` ### ReduceConcurrent

Reduces the slice to a single value by applying the reducer function to each item in the slice concurrently.

Signature: ```go func ReduceConcurrent[T any](slice []T, initial T, reducer func(index int, item T, agg T) T, numThreads int) T ``` Example:[运行](https://go.dev/play/p/Tjwe6OtaG07) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10} result := slice.ReduceConcurrent(nums, 0, func(_ int, item, agg int) int { return agg + item }, 1) fmt.Println(result) // Output: // 55 } ``` ### ReduceBy

Produces a value from slice by accumulating the result of each element as passed through the reducer function.

Signature: ```go func ReduceBy[T any, U any](slice []T, initial U, reducer func(index int, item T, agg U) U) U ``` Example:[Run](https://go.dev/play/p/YKDpLi7gtee) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result1 := slice.ReduceBy([]int{1, 2, 3, 4}, 0, func(_ int, item int, agg int) int { return agg + item }) result2 := slice.ReduceBy([]int{1, 2, 3, 4}, "", func(_ int, item int, agg string) string { return agg + fmt.Sprintf("%v", item) }) fmt.Println(result1) fmt.Println(result2) // Output: // 10 // 1234 } ``` ### ReduceRight

ReduceRight is like ReduceBy, but it iterates over elements of slice from right to left.

Signature: ```go func ReduceRight[T any, U any](slice []T, initial U, reducer func(index int, item T, agg U) U) U ``` Example:[Run](https://go.dev/play/p/qT9dZC03A1K) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result := slice.ReduceRight([]int{1, 2, 3, 4}, "", func(_ int, item int, agg string) string { return agg + fmt.Sprintf("%v", item) }) fmt.Println(result) // Output: // 4321 } ``` ### Replace

Returns a copy of the slice with the first n non-overlapping instances of old replaced by new.

Signature: ```go func Replace[T comparable](slice []T, old T, new T, n int) []T ``` Example:[Run](https://go.dev/play/p/P5mZp7IhOFo) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { strs := []string{"a", "b", "c", "a"} result1 := slice.Replace(strs, "a", "x", 0) result2 := slice.Replace(strs, "a", "x", 1) result3 := slice.Replace(strs, "a", "x", 2) result4 := slice.Replace(strs, "a", "x", 3) result5 := slice.Replace(strs, "a", "x", -1) fmt.Println(result1) fmt.Println(result2) fmt.Println(result3) fmt.Println(result4) fmt.Println(result5) // Output: // [a b c a] // [x b c a] // [x b c x] // [x b c x] // [x b c x] } ``` ### ReplaceAll

Returns a copy of the slice with the first n non-overlapping instances of old replaced by new.

Signature: ```go func ReplaceAll[T comparable](slice []T, old T, new T) []T ``` Example:[Run](https://go.dev/play/p/CzqXMsuYUrx) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result := slice.ReplaceAll([]string{"a", "b", "c", "a"}, "a", "x") fmt.Println(result) // Output: // [x b c x] } ``` ### Repeat

Creates a slice with length n whose elements are passed param item.

Signature: ```go func Repeat[T any](item T, n int) []T ``` Example:[Run](https://go.dev/play/p/1CbOmtgILUU) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result := slice.Repeat("a", 3) fmt.Println(result) // Output: // [a a a] } ``` ### Shuffle

Creates an slice of shuffled values.

Signature: ```go func Shuffle[T any](slice []T) []T ``` Example:[Run](https://go.dev/play/p/YHvhnWGU3Ge) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4, 5} result := slice.Shuffle(nums) fmt.Println(res) // Output: // [3 1 5 4 2] (random order) } ``` ### IsAscending

Checks if a slice is ascending order.

Signature: ```go func IsAscending[T constraints.Ordered](slice []T) bool ``` Example:[Run](https://go.dev/play/p/9CtsFjet4SH) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result1 := slice.IsAscending([]int{1, 2, 3, 4, 5}) result2 := slice.IsAscending([]int{5, 4, 3, 2, 1}) result3 := slice.IsAscending([]int{2, 1, 3, 4, 5}) fmt.Println(result1) fmt.Println(result2) fmt.Println(result3) // Output: // true // false // false } ``` ### IsDescending

Checks if a slice is descending order.

Signature: ```go func IsDescending[T constraints.Ordered](slice []T) bool ``` Example:[Run](https://go.dev/play/p/U_LljFXma14) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result1 := slice.IsDescending([]int{5, 4, 3, 2, 1}) result2 := slice.IsDescending([]int{1, 2, 3, 4, 5}) result3 := slice.IsDescending([]int{2, 1, 3, 4, 5}) fmt.Println(result1) fmt.Println(result2) fmt.Println(result3) // Output: // true // false // false } ``` ### IsSorted

Checks if a slice is sorted (ascending or descending).

Signature: ```go func IsSorted[T constraints.Ordered](slice []T) bool ``` Example:[Run](https://go.dev/play/p/nCE8wPLwSA-) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result1 := slice.IsSorted([]int{5, 4, 3, 2, 1}) result2 := slice.IsSorted([]int{1, 2, 3, 4, 5}) result3 := slice.IsSorted([]int{2, 1, 3, 4, 5}) fmt.Println(result1) fmt.Println(result2) fmt.Println(result3) // Output: // true // true // false } ``` ### IsSortedByKey

Checks if a slice is sorted by iteratee function.

Signature: ```go func IsSortedByKey[T any, K constraints.Ordered](slice []T, iteratee func(item T) K) bool ``` Example:[Run](https://go.dev/play/p/tUoGB7DOHI4) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result1 := slice.IsSortedByKey([]string{"a", "ab", "abc"}, func(s string) int { return len(s) }) result2 := slice.IsSortedByKey([]string{"abc", "ab", "a"}, func(s string) int { return len(s) }) result3 := slice.IsSortedByKey([]string{"abc", "a", "ab"}, func(s string) int { return len(s) }) fmt.Println(result1) fmt.Println(result2) fmt.Println(result3) // Output: // true // true // false } ``` ### Sort

Sorts a slice of any ordered type(number or string), use quick sort algrithm. Default sort order is ascending (asc), if want descending order, set param `sortOrder` to `desc`. Ordered type: number(all ints uints floats) or string.

Signature: ```go func Sort[T constraints.Ordered](slice []T, sortOrder ...string) ``` Example:[Run](https://go.dev/play/p/V9AVjzf_4Fk) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { numbers := []int{1, 4, 3, 2, 5} slice.Sort(numbers) fmt.Println(numbers) // [1 2 3 4 5] slice.Sort(numbers, "desc") fmt.Println(numbers) // [5 4 3 2 1] strings := []string{"a", "d", "c", "b", "e"} slice.Sort(strings) fmt.Println(strings) //[a b c d e} slice.Sort(strings, "desc") fmt.Println(strings) //[e d c b a] } ``` ### SortBy

Sorts the slice in ascending order as determined by the less function. This sort is not guaranteed to be stable.

Signature: ```go func SortBy[T any](slice []T, less func(a, b T) bool) ``` Example:[Run](https://go.dev/play/p/DAhLQSZEumm) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { numbers := []int{1, 4, 3, 2, 5} slice.SortBy(numbers, func(a, b int) bool { return a < b }) fmt.Println(numbers) // [1 2 3 4 5] type User struct { Name string Age uint } users := []User{ {Name: "a", Age: 21}, {Name: "b", Age: 15}, {Name: "c", Age: 100}} slice.SortBy(users, func(a, b User) bool { return a.Age < b.Age }) fmt.Printf("sort users by age: %v", users) // output // [{b 15} {a 21} {c 100}] } ``` ### SortByField

Sort struct slice by field. Slice element should be struct, `field` param type should be int, uint, string, or bool. Default sort type is ascending (asc), if descending order, set `sortType` param to desc.

Signature: ```go func SortByField(slice any, field string, sortType ...string) error ``` Example:[Run](https://go.dev/play/p/fU1prOBP9p1) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { type User struct { Name string Age uint } users := []User{ {Name: "a", Age: 21}, {Name: "b", Age: 15}, {Name: "c", Age: 100}} err := slice.SortByField(users, "Age", "desc") if err != nil { return } fmt.Println(users) // Output: // [{c 100} {a 21} {b 15}] } ``` ### Some

Return true if any of the values in the list pass the predicate function.

Signature: ```go func Some[T any](slice []T, predicate func(index int, item T) bool) bool ``` Example:[Run](https://go.dev/play/p/4pO9Xf9NDGS) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 5} isEven := func(i, num int) bool { return num%2 == 0 } result := slice.Some(nums, isEven) fmt.Println(result) // Output: // true } ``` ### StringSlice

Convert interface slice to string slice.

> ⚠️ This function is deprecated. use generic feature of go1.18+ for replacement Signature: ```go func StringSlice(slice any) []string ``` Example:[Run](https://go.dev/play/p/W0TZDWCPFcI) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { strs := []interface{}{"a", "b", "c"} result := slice.StringSlice(strs) //[]string{"a", "b", "c"} fmt.Println(result) // Output: // [a b c] } ``` ### SymmetricDifference

Create a slice whose element is in given slices, but not in both slices.

Signature: ```go func SymmetricDifference[T comparable](slices ...[]T) []T ``` Example:[Run](https://go.dev/play/p/1CbOmtgILUU) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums1 := []int{1, 2, 3} nums2 := []int{1, 2, 4} result := slice.SymmetricDifference(nums1, nums2) fmt.Println(result) // Output: // [3 4] } ``` ### ToSlice

Creates a slice of give items.

Signature: ```go func ToSlice[T any](items ...T) []T ``` Example:[Run](https://go.dev/play/p/YzbzVq5kscN) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result := slice.ToSlice("a", "b", "c") fmt.Println(result) // Output: // [a b c] } ``` ### ToSlicePointer

Returns a pointer to the slices of a variable parameter transformation

Signature: ```go func ToSlicePointer[T any](items ...T) []*T ``` Example:[Run](https://go.dev/play/p/gx4tr6_VXSF) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { str1 := "a" str2 := "b" result := slice.ToSlicePointer(str1, str2) expect := []*string{&str1, &str2} isEqual := reflect.DeepEqual(result, expect) fmt.Println(isEqual) // Output: // true } ``` ### Unique

Remove duplicate elements in slice.

Signature: ```go func Unique[T comparable](slice []T) []T ``` Example:[Run](https://go.dev/play/p/AXw0R3ZTE6a) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result := slice.Unique([]string{"a", "a", "b"}) fmt.Println(result) // Output: // [a b] } ``` ### UniqueBy

Removes duplicate elements from the input slice based on the values returned by the iteratee function. this function maintains the order of the elements.

Signature: ```go func UniqueBy[T any, U comparable](slice []T, iteratee func(item T) U) []T ``` Example:[Run](https://go.dev/play/p/GY7JE4yikrl) ```go import ( "fmt" "github.com/duke-git/lancet/slice" ) func main() { nums := []int{1, 2, 3, 4, 5, 6} result := slice.UniqueBy(nums, func(val int) int { return val % 3 }) fmt.Println(result) // Output: // [1 2 3] } ``` ### UniqueByComparator

Removes duplicate elements from the input slice using the provided comparator function. The function maintains the order of the elements.

Signature: ```go func UniqueByComparator[T comparable](slice []T, comparator func(item T, other T) bool) []T ``` Example:[Run](https://go.dev/play/p/rwSacr-ZHsR) ```go import ( "fmt" "github.com/duke-git/lancet/slice" ) func main() { uniqueNums := slice.UniqueByComparator([]int{1, 2, 3, 1, 2, 4, 5, 6, 4}, func(item int, other int) bool { return item == other }) caseInsensitiveStrings := slice.UniqueByComparator([]string{"apple", "banana", "Apple", "cherry", "Banana", "date"}, func(item string, other string) bool { return strings.ToLower(item) == strings.ToLower(other) }) fmt.Println(uniqueNums) fmt.Println(caseInsensitiveStrings) // Output: // [1 2 3 4 5 6] // [apple banana cherry date] } ``` ### UniqueByConcurrent

Removes duplicate elements from the slice by parallel.

Signature: ```go func UniqueByConcurrent[T comparable](slice []T, comparator func(item T, other T) bool, numThreads int) []T ``` Example:[Runs](https://go.dev/play/p/wXZ7LcYRMGL) ```go import ( "fmt" "github.com/duke-git/lancet/slice" ) func main() { nums := []int{1, 2, 3, 1, 2, 4, 5, 6, 4, 7} comparator := func(item int, other int) bool { return item == other } result := slice.UniqueByConcurrent(nums,comparator, 4) fmt.Println(result) // Output: // [1 2 3 4 5 6 7] } ``` ### UniqueByField

Remove duplicate elements in struct slice by struct field.

Signature: ```go func UniqueByField[T any](slice []T, field string) ([]T, error) ``` Example:[Runs](https://go.dev/play/p/6cifcZSPIGu) ```go import ( "fmt" "github.com/duke-git/lancet/slice" ) func main() { type User struct { ID int `json:"id"` Name string `json:"name"` } users := []User{ {ID: 1, Name: "a"}, {ID: 2, Name: "b"}, {ID: 1, Name: "c"}, } result, err := slice.UniqueByField(users, "ID") if err != nil { } fmt.Println(result) // Output: // [{1 a} {2 b}] } ``` ### Union

Creates a slice of unique values, in order, from all given slices. using == for equality comparisons.

Signature: ```go func Union[T comparable](slices ...[]T) []T ``` Example:[Run](https://go.dev/play/p/hfXV1iRIZOf) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums1 := []int{1, 3, 4, 6} nums2 := []int{1, 2, 5, 6} result := slice.Union(nums1, nums2) fmt.Println(result) // Output: // [1 3 4 6 2 5] } ``` ### UnionBy

UnionBy is like Union, what's more it accepts iteratee which is invoked for each element of each slice.

Signature: ```go func UnionBy[T any, V comparable](predicate func(item T) V, slices ...[]T) []T ``` Example:[Run](https://go.dev/play/p/HGKHfxKQsFi) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4} divideTwo := func(n int) int { return n / 2 } result := slice.UnionBy(divideTwo, nums) fmt.Println(result) // Output: // [1 2 4] } ``` ### UpdateAt

Update the slice element at index. if param index < 0 or index <= len(slice), will return error.

Signature: ```go func UpdateAt[T any](slice []T, index int, value T) []T ``` Example:[Run](https://go.dev/play/p/f3mh2KloWVm) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result1 := slice.UpdateAt([]string{"a", "b", "c"}, -1, "1") result2 := slice.UpdateAt([]string{"a", "b", "c"}, 0, "1") result3 := slice.UpdateAt([]string{"a", "b", "c"}, 1, "1") result4 := slice.UpdateAt([]string{"a", "b", "c"}, 2, "1") result5 := slice.UpdateAt([]string{"a", "b", "c"}, 3, "1") fmt.Println(result1) fmt.Println(result2) fmt.Println(result3) fmt.Println(result4) fmt.Println(result5) // Output: // [a b c] // [1 b c] // [a 1 c] // [a b 1] // [a b c] } ``` ### Without

Creates a slice excluding all given items.

Signature: ```go func Without[T comparable](slice []T, items ...T) []T ``` Example:[Run](https://go.dev/play/p/bwhEXEypThg) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result := slice.Without([]int{1, 2, 3, 4}, 1, 2) fmt.Println(result) // Output: // [3 4] } ``` ### KeyBy

Converts a slice to a map based on a callback function.

Signature: ```go func KeyBy[T any, U comparable](slice []T, iteratee func(item T) U) map[U]T ``` Example:[Run](https://go.dev/play/p/uXod2LWD1Kg) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result := slice.KeyBy([]string{"a", "ab", "abc"}, func(str string) int { return len(str) }) fmt.Println(result) // Output: // map[1:a 2:ab 3:abc] } ``` ### Join

Join the slice item with specify separator.

Signature: ```go func Join[T any](s []T, separator string) string ``` Example:[Run](https://go.dev/play/p/huKzqwNDD7V) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4, 5} result1 := slice.Join(nums, ",") result2 := slice.Join(nums, "-") fmt.Println(result1) fmt.Println(result2) // Output: // 1,2,3,4,5 // 1-2-3-4-5 } ``` ### Partition

Partition all slice elements with the evaluation of the given predicate functions.

Signature: ```go func Partition[T any](slice []T, predicates ...func(item T) bool) [][]T ``` Example:[Run](https://go.dev/play/p/lkQ3Ri2NQhV) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4, 5} result1 := slice.Partition(nums) result2 := slice.Partition(nums, func(n int) bool { return n%2 == 0 }) result3 := slice.Partition(nums, func(n int) bool { return n == 1 || n == 2 }, func(n int) bool { return n == 2 || n == 3 || n == 4 }) fmt.Println(result1) fmt.Println(result2) fmt.Println(result3) // Output: // [[1 2 3 4 5]] // [[2 4] [1 3 5]] // [[1 2] [3 4] [5]] } ``` ### Random

Random get a random item of slice, return idx=-1 when slice is empty.

Signature: ```go func Random[T any](slice []T) (val T, idx int) ``` Example:[Run](https://go.dev/play/p/UzpGQptWppw) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4, 5} val, idx := slice.Random(nums) if idx >= 0 && idx < len(nums) && slice.Contain(nums, val) { fmt.Println("okk") } // Output: // okk } ``` ### SetToDefaultIf

Sets elements to their default value if they match the given predicate. It retains the positions of the elements in the slice. It returns slice of T and the count of modified slice items

Signature: ```go func SetToDefaultIf[T any](slice []T, predicate func(T) bool) ([]T, int) ``` Example:[Run](https://go.dev/play/p/9AXGlPRC0-A) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { strs := []string{"a", "b", "a", "c", "d", "a"} modifiedStrs, count := slice.SetToDefaultIf(strs, func(s string) bool { return "a" == s }) fmt.Println(modifiedStrs) fmt.Println(count) // Output: // [ b c d ] // 3 } ``` ### Break

Splits a slice into two based on a predicate function. It starts appending to the second slice after the first element that matches the predicate. All elements after the first match are included in the second slice, regardless of whether they match the predicate or not.

Signature: ```go func Break[T any](values []T, predicate func(T) bool) ([]T, []T) ``` Example:[Run](https://go.dev/play/p/yLYcBTyeQIz) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4, 5} even := func(n int) bool { return n%2 == 0 } resultEven, resultAfterFirstEven := slice.Break(nums, even) fmt.Println(resultEven) fmt.Println(resultAfterFirstEven) // Output: // [1] // [2 3 4 5] } ``` ### RightPadding

RightPadding adds padding to the right end of a slice.

Signature: ```go func RightPadding[T any](slice []T, paddingValue T, paddingLength int) []T ``` Example:[Run](https://go.dev/play/p/0_2rlLEMBXL) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4, 5} padded := slice.RightPadding(nums, 0, 3) fmt.Println(padded) // Output: // [1 2 3 4 5 0 0 0] } ``` ### LeftPadding

LeftPadding adds padding to the left begin of a slice.

Signature: ```go func LeftPadding[T any](slice []T, paddingValue T, paddingLength int) []T ``` Example:[Run](https://go.dev/play/p/jlQVoelLl2k) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { nums := []int{1, 2, 3, 4, 5} padded := slice.LeftPadding(nums, 0, 3) fmt.Println(padded) // Output: // [0 0 0 1 2 3 4 5] } ``` ### Frequency

Counts the frequency of each element in the slice.

Signature: ```go func Frequency[T comparable](slice []T) map[T]int ``` Example:[Run](https://go.dev/play/p/CW3UVNdUZOq) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { strs := []string{"a", "b", "b", "c", "c", "c"} result := slice.Frequency(strs) fmt.Println(result) // Output: // map[a:1 b:2 c:3] } ``` ### JoinFunc

Joins the slice elements into a single string with the given separator.

Signature: ```go func JoinFunc[T any](slice []T, sep string, transform func(T) T) string ``` Example:[Run](todo) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { result := slice.JoinFunc([]string{"a", "b", "c"}, ", ", func(s string) string { return strings.ToUpper(s) }) fmt.Println(result) // Output: // A, B, C } ``` ### ConcatBy

Concats the elements of a slice into a single value using the provided separator and connector function.

Signature: ```go func ConcatBy[T any](slice []T, sep T, connector func(T, T) T) T ``` Example:[Run](todo) ```go import ( "fmt" "github.com/duke-git/lancet/v2/slice" ) func main() { type Person struct { Name string Age int } people := []Person{ {Name: "Alice", Age: 30}, {Name: "Bob", Age: 25}, {Name: "Charlie", Age: 35}, } sep := Person{Name: " | ", Age: 0} personConnector := func(a, b Person) Person { return Person{Name: a.Name + b.Name, Age: a.Age + b.Age} } result := slice.ConcatBy(people, sep, personConnector) fmt.Println(result.Name) fmt.Println(result.Age) // Output: // Alice | Bob | Charlie // 90 } ```