release v2.0.3

docs: add maputil docs in read me file
docs: add doc for maputil package
2026-02-06 05:42:25 +08:00 · 2022-04-06 10:54:54 +08:00 · 2022-04-05 14:24:33 +08:00 · 2022-04-05 14:16:58 +08:00 · 2022-04-05 13:47:13 +08:00 · 2022-04-01 18:06:34 +08:00
34 changed files with 2118 additions and 71 deletions
--- a/README.md
+++ b/README.md
@@ -4,13 +4,12 @@
 <br/>

 ![Go version](https://img.shields.io/badge/go-%3E%3D1.16<recommend>-9cf)
-[![Release](https://img.shields.io/badge/release-2.0.0-green.svg)](https://github.com/duke-git/lancet/releases)
+[![Release](https://img.shields.io/badge/release-2.0.3-green.svg)](https://github.com/duke-git/lancet/releases)
 [![GoDoc](https://godoc.org/github.com/duke-git/lancet/v2?status.svg)](https://pkg.go.dev/github.com/duke-git/lancet/v2)
 [![Go Report Card](https://goreportcard.com/badge/github.com/duke-git/lancet/v2)](https://goreportcard.com/report/github.com/duke-git/lancet/v2)
 [![test](https://github.com/duke-git/lancet/actions/workflows/codecov.yml/badge.svg?branch=main&event=push)](https://github.com/duke-git/lancet/actions/workflows/codecov.yml)
 [![codecov](https://codecov.io/gh/duke-git/lancet/branch/main/graph/badge.svg?token=FC48T1F078)](https://codecov.io/gh/duke-git/lancet)
 [![License](https://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/duke-git/lancet/blob/main/LICENSE)
-
 </div>

 <div STYLE="page-break-after: always;"></div>
@@ -36,9 +35,9 @@ English | [简体中文](./README_zh-CN.md)
 go get github.com/duke-git/lancet/v2 // will install latest version of v2.x.x
 ```

-2. <b>For users who use version below go1.18, you should install v1.x.x. now latest v1 is v1.2.6. </b>
+2. <b>For users who use version below go1.18, you should install v1.x.x. now latest v1 is v1.2.7. </b>
 ```go
-go get github.com/duke-git/lancet@v1.2.6 // below go1.18, install latest version of v1.x.x
+go get github.com/duke-git/lancet@v1.2.7 // below go1.18, install latest version of v1.x.x
 ```

 ## Usage
@@ -58,7 +57,7 @@ package main

 import (
    "fmt"
-    "github.com/duke-git/lancet/strutil"
+    "github.com/duke-git/lancet/v2/strutil"
 )

 func main() {
@@ -175,6 +174,14 @@ import "github.com/duke-git/lancet/v2/datetime"
 - [GetNightTimestamp](https://github.com/duke-git/lancet/blob/main/docs/datetime.md#GetNightTimestamp)
 - [FormatTimeToStr](https://github.com/duke-git/lancet/blob/main/docs/datetime.md#FormatTimeToStr)
 - [FormatStrToTime](https://github.com/duke-git/lancet/blob/main/docs/datetime.md#FormatStrToTime)
+- [NewUnix](https://github.com/duke-git/lancet/blob/main/docs/datetime.md#NewUnix)
+- [NewUnixNow](https://github.com/duke-git/lancet/blob/main/docs/datetime.md#NewUnixNow)
+- [NewFormat](https://github.com/duke-git/lancet/blob/main/docs/datetime.md#NewFormat)
+- [NewISO8601](https://github.com/duke-git/lancet/blob/main/docs/datetime.md#NewISO8601)
+- [ToUnix](https://github.com/duke-git/lancet/blob/main/docs/datetime.md#ToUnix)
+- [ToFormat](https://github.com/duke-git/lancet/blob/main/docs/datetime.md#ToFormat)
+- [ToFormatForTpl](https://github.com/duke-git/lancet/blob/main/docs/datetime.md#ToFormatForTpl)
+- [ToIso8601](https://github.com/duke-git/lancet/blob/main/docs/datetime.md#ToIso8601)

 ### Fileutil package implements some basic functions for file operations.

@@ -223,6 +230,22 @@ import "github.com/duke-git/lancet/v2/function"
 - [Watcher](https://github.com/duke-git/lancet/blob/main/docs/function.md#Watcher)


+### Maputil package includes some functions to manipulate map.
+
+```go
+import "github.com/duke-git/lancet/v2/maputil"
+```
+
+#### Function list:
+- [ForEach](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#ForEach)
+- [Filter](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#Filter)
+- [Intersect](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#Intersect)
+- [Keys](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#Keys)
+- [Merge](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#Merge)
+- [Minus](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#Minus)
+- [Values](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#Values)
+
+
 ### Mathutil package implements some functions for math calculation.

 ```go
@@ -230,9 +253,12 @@ import "github.com/duke-git/lancet/v2/mathutil"
 ```

 #### Function list:
+- [Average](https://github.com/duke-git/lancet/blob/main/docs/mathutil.md#Average)
 - [Exponent](https://github.com/duke-git/lancet/blob/main/docs/mathutil.md#Exponent)
 - [Fibonacci](https://github.com/duke-git/lancet/blob/main/docs/mathutil.md#Fibonacci)
 - [Factorial](https://github.com/duke-git/lancet/blob/main/docs/mathutil.md#Factorial)
+- [Max](https://github.com/duke-git/lancet/blob/main/docs/mathutil.md#Max)
+- [Min](https://github.com/duke-git/lancet/blob/main/docs/mathutil.md#Min)
 - [Percent](https://github.com/duke-git/lancet/blob/main/docs/mathutil.md#Percent)
 - [RoundToFloat](https://github.com/duke-git/lancet/blob/main/docs/mathutil.md#RoundToFloat)
 - [RoundToString](https://github.com/duke-git/lancet/blob/main/docs/mathutil.md#RoundToString)
@@ -309,6 +335,7 @@ import "github.com/duke-git/lancet/v2/slice"
 - [FlattenDeep](#FlattenDeep)
 - [ForEach](https://github.com/duke-git/lancet/blob/main/docs/slice.md#ForEach)
 - [GroupBy](https://github.com/duke-git/lancet/blob/main/docs/slice.md#GroupBy)
+- [GroupWith](https://github.com/duke-git/lancet/blob/main/docs/slice.md#GroupWith)
 - [IntSlice](https://github.com/duke-git/lancet/blob/main/docs/slice.md#IntSlice)
 - [InterfaceSlice](https://github.com/duke-git/lancet/blob/main/docs/slice.md#InterfaceSlice)
 - [Intersection](https://github.com/duke-git/lancet/blob/main/docs/slice.md#Intersection)
@@ -320,6 +347,7 @@ import "github.com/duke-git/lancet/v2/slice"
 - [SortByField](https://github.com/duke-git/lancet/blob/main/docs/slice.md#SortByField)
 - [Some](https://github.com/duke-git/lancet/blob/main/docs/slice.md#Some)
 - [StringSlice](https://github.com/duke-git/lancet/blob/main/docs/slice.md#StringSlice)
+- [SymmetricDifference](https://github.com/duke-git/lancet/blob/main/docs/slice.md#SymmetricDifference)
 - [Unique](https://github.com/duke-git/lancet/blob/main/docs/slice.md#Unique)
 - [Union](https://github.com/duke-git/lancet/blob/main/docs/slice.md#Union)
 - [UpdateAt](https://github.com/duke-git/lancet/blob/main/docs/slice.md#UpdateAt)
--- a/README_zh-CN.md
+++ b/README_zh-CN.md
@@ -4,13 +4,12 @@
 <br/>

 ![Go version](https://img.shields.io/badge/go-%3E%3D1.16<recommend>-9cf)
-[![Release](https://img.shields.io/badge/release-2.0.0-green.svg)](https://github.com/duke-git/lancet/releases)
+[![Release](https://img.shields.io/badge/release-2.0.3-green.svg)](https://github.com/duke-git/lancet/releases)
 [![GoDoc](https://godoc.org/github.com/duke-git/lancet/v2?status.svg)](https://pkg.go.dev/github.com/duke-git/lancet/v2)
 [![Go Report Card](https://goreportcard.com/badge/github.com/duke-git/lancet/v2)](https://goreportcard.com/report/github.com/duke-git/lancet/v2)
 [![test](https://github.com/duke-git/lancet/actions/workflows/codecov.yml/badge.svg?branch=main&event=push)](https://github.com/duke-git/lancet/actions/workflows/codecov.yml)
 [![codecov](https://codecov.io/gh/duke-git/lancet/branch/main/graph/badge.svg?token=FC48T1F078)](https://codecov.io/gh/duke-git/lancet)
 [![License](https://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/duke-git/lancet/blob/main/LICENSE)
-
 </div>

 <div STYLE="page-break-after: always;"></div>
@@ -36,9 +35,9 @@
 go get github.com/duke-git/lancet/v2 //安装v2最新版本v2.x.x
 ```

-2. <b>使用go1.18以下版本的用户，必须安装v1.x.x。目前最新的v1版本是v1.2.6。</b>
+2. <b>使用go1.18以下版本的用户，必须安装v1.x.x。目前最新的v1版本是v1.2.7。</b>
 ```go
-go get github.com/duke-git/lancet@v1.2.6 // 使用go1.18以下版本, 必须安装v1.x.x版本
+go get github.com/duke-git/lancet@v1.2.7 // 使用go1.18以下版本, 必须安装v1.x.x版本
 ```

 ## 用法
@@ -58,7 +57,7 @@ package main

 import (
    "fmt"
-    "github.com/duke-git/lancet/strutil"
+    "github.com/duke-git/lancet/v2/strutil"
 )

 func main() {
@@ -174,6 +173,14 @@ import "github.com/duke-git/lancet/v2/datetime"
 - [GetNightTimestamp](https://github.com/duke-git/lancet/blob/main/docs/datetime_zh-CN.md#GetNightTimestamp)
 - [FormatTimeToStr](https://github.com/duke-git/lancet/blob/main/docs/datetime_zh-CN.md#FormatTimeToStr)
 - [FormatStrToTime](https://github.com/duke-git/lancet/blob/main/docs/datetime_zh-CN.md#FormatStrToTime)
+- [NewUnix](https://github.com/duke-git/lancet/blob/main/docs/datetime_zh-CN.md#NewUnix)
+- [NewUnixNow](https://github.com/duke-git/lancet/blob/main/docs/datetime_zh-CN.md#NewUnixNow)
+- [NewFormat](https://github.com/duke-git/lancet/blob/main/docs/datetime_zh-CN.md#NewFormat)
+- [NewISO8601](https://github.com/duke-git/lancet/blob/main/docs/datetime_zh-CN.md#NewISO8601)
+- [ToUnix](https://github.com/duke-git/lancet/blob/main/docs/datetime_zh-CN.md#ToUnix)
+- [ToFormat](https://github.com/duke-git/lancet/blob/main/docs/datetime_zh-CN.md#ToFormat)
+- [ToFormatForTpl](https://github.com/duke-git/lancet/blob/main/docs/datetime_zh-CN.md#ToFormatForTpl)
+- [ToIso8601](https://github.com/duke-git/lancet/blob/main/docs/datetime_zh-CN.md#ToIso8601)

 ### fileutil包支持文件基本操作。

@@ -222,6 +229,22 @@ import "github.com/duke-git/lancet/v2/function"
 - [Delay](https://github.com/duke-git/lancet/blob/main/docs/function_zh-CN.md#Delay)
 - [Watcher](https://github.com/duke-git/lancet/blob/main/docs/function_zh-CN.md#Watcher)

+
+### maputil包包括一些操作map的函数.
+
+```go
+import "github.com/duke-git/lancet/v2/maputil"
+```
+
+#### 函数列表:
+- [ForEach](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN.md#ForEach)
+- [Filter](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN.md#Filter)
+- [Intersect](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN.md#Intersect)
+- [Keys](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN.md#Keys)
+- [Merge](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN.md#Merge)
+- [Minus](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN.md#Minus)
+- [Values](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN.md#Values)
+
 ### mathutil包实现了一些数学计算的函数。

 ```go
@@ -229,9 +252,12 @@ import "github.com/duke-git/lancet/v2/mathutil"
 ```

 #### Function list:
+- [Average](https://github.com/duke-git/lancet/blob/main/docs/mathutil_zh-CN.md#Average)
 - [Exponent](https://github.com/duke-git/lancet/blob/main/docs/mathutil_zh-CN.md#Exponent)
 - [Fibonacci](https://github.com/duke-git/lancet/blob/main/docs/mathutil_zh-CN.md#Fibonacci)
 - [Factorial](https://github.com/duke-git/lancet/blob/main/docs/mathutil_zh-CN.md#Factorial)
+- [Max](https://github.com/duke-git/lancet/blob/main/docs/mathutil_zh-CN.md#Max)
+- [Min](https://github.com/duke-git/lancet/blob/main/docs/mathutil_zh-CN.md#Min)
 - [Percent](https://github.com/duke-git/lancet/blob/main/docs/mathutil_zh-CN.md#Percent)
 - [RoundToFloat](https://github.com/duke-git/lancet/blob/main/docs/mathutil_zh-CN.md#RoundToFloat)
 - [RoundToString](https://github.com/duke-git/lancet/blob/main/docs/mathutil_zh-CN.md#RoundToString)
@@ -307,6 +333,7 @@ import "github.com/duke-git/lancet/v2/slice"
 - [FlattenDeep](#FlattenDeep)
 - [ForEach](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#ForEach)
 - [GroupBy](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#GroupBy)
+- [GroupWith](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#GroupWith)
 - [IntSlice](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#IntSlice)
 - [InterfaceSlice](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#InterfaceSlice)
 - [Intersection](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#Intersection)
@@ -318,6 +345,7 @@ import "github.com/duke-git/lancet/v2/slice"
 - [SortByField](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#SortByField)
 - [Some](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#Some)
 - [StringSlice](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#StringSlice)
+- [SymmetricDifference](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#SymmetricDifference)
 - [Unique](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#Unique)
 - [Union](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#Union)
 - [UpdateAt](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#UpdateAt)
--- a/algorithm/sorter.go
+++ b/algorithm/sorter.go
@@ -37,7 +37,7 @@ func InsertionSort[T any](slice []T, comparator lancetconstraints.Comparator) []
 			preIndex--
 		}

-		slice[preIndex+1] = preItem
+		slice[preIndex+1] = currentItem
 	}

 	return slice
--- a/algorithm/sorter_test.go
+++ b/algorithm/sorter_test.go
@@ -89,10 +89,10 @@ func TestInsertionSort(t *testing.T) {
 	asssert := internal.NewAssert(t, "TestInsertionSort")

 	comparator := &peopleAgeComparator{}
-	sortedPeopleByAge := SelectionSort(peoples, comparator)
+	sortedPeopleByAge := InsertionSort(peoples, comparator)
 	t.Log(sortedPeopleByAge)

-	expected := "[{d 8} {b 10} {c 17} {a 20} {e 28}]"
+	expected := "[{e 28} {a 20} {c 17} {b 10} {d 8}]"
 	actual := fmt.Sprintf("%v", sortedPeopleByAge)

 	asssert.Equal(expected, actual)
--- a/convertor/convertor.go
+++ b/convertor/convertor.go
@@ -6,9 +6,10 @@ package convertor

 import (
 	"bytes"
-	"encoding/gob"
+	"encoding/binary"
 	"encoding/json"
 	"fmt"
+	"math"
 	"reflect"
 	"regexp"
 	"strconv"
@@ -21,14 +22,44 @@ func ToBool(s string) (bool, error) {
 }

 // ToBytes convert interface to bytes
-func ToBytes(data any) ([]byte, error) {
-	var buf bytes.Buffer
-	enc := gob.NewEncoder(&buf)
-	err := enc.Encode(data)
-	if err != nil {
-		return nil, err
+func ToBytes(value any) ([]byte, error) {
+	v := reflect.ValueOf(value)
+
+	switch value.(type) {
+	case int, int8, int16, int32, int64:
+		number := v.Int()
+		buf := bytes.NewBuffer([]byte{})
+		buf.Reset()
+		err := binary.Write(buf, binary.BigEndian, number)
+		return buf.Bytes(), err
+	case uint, uint8, uint16, uint32, uint64:
+		number := v.Uint()
+		buf := bytes.NewBuffer([]byte{})
+		buf.Reset()
+		err := binary.Write(buf, binary.BigEndian, number)
+		return buf.Bytes(), err
+	case float32:
+		number := float32(v.Float())
+		bits := math.Float32bits(number)
+		bytes := make([]byte, 4)
+		binary.BigEndian.PutUint32(bytes, bits)
+		return bytes, nil
+	case float64:
+		number := v.Float()
+		bits := math.Float64bits(number)
+		bytes := make([]byte, 8)
+		binary.BigEndian.PutUint64(bytes, bits)
+		return bytes, nil
+	case bool:
+		return strconv.AppendBool([]byte{}, v.Bool()), nil
+	case string:
+		return []byte(v.String()), nil
+	case []byte:
+		return v.Bytes(), nil
+	default:
+		newValue, err := json.Marshal(value)
+		return newValue, err
 	}
-	return buf.Bytes(), nil
 }

 // ToChar convert string to char slice
--- a/convertor/convertor_test.go
+++ b/convertor/convertor_test.go
@@ -42,14 +42,21 @@ func TestToBytes(t *testing.T) {
 		"1",
 	}
 	expected := [][]byte{
-		{3, 4, 0, 0},
-		{3, 2, 0, 0},
-		{4, 12, 0, 1, 49},
+		{0, 0, 0, 0, 0, 0, 0, 0},
+		{102, 97, 108, 115, 101},
+		{49},
 	}
 	for i := 0; i < len(cases); i++ {
 		actual, _ := ToBytes(cases[i])
 		assert.Equal(expected[i], actual)
 	}
+
+	bytesData, err := ToBytes("abc")
+	if err != nil {
+		t.Error(err)
+		t.Fail()
+	}
+	assert.Equal("abc", ToString(bytesData))
 }

 func TestToInt(t *testing.T) {
--- a/datastructure/link/doublylink_test.go
+++ b/datastructure/link/doublylink_test.go
@@ -44,14 +44,11 @@ func TestDoublyLink_InsertAt(t *testing.T) {
 	err := link.InsertAt(1, 1)
 	assert.IsNotNil(err)

-	err = link.InsertAt(0, 1)
-	err = link.InsertAt(1, 2)
-	err = link.InsertAt(2, 4)
-	err = link.InsertAt(2, 3)
+	link.InsertAt(0, 1)
+	link.InsertAt(1, 2)
+	link.InsertAt(2, 4)
+	link.InsertAt(2, 3)

-	if err != nil {
-		t.FailNow()
-	}
 	link.Print()

 	expected := []int{1, 2, 3, 4}
--- a/datastructure/link/singlylink.go
+++ b/datastructure/link/singlylink.go
@@ -3,6 +3,7 @@ package datastructure
 import (
 	"errors"
 	"fmt"
+	"reflect"

 	"github.com/duke-git/lancet/v2/datastructure"
 )
@@ -144,6 +145,27 @@ func (link *SinglyLink[T]) DeleteAt(index int) error {
 	return errors.New("delete error")
 }

+// DeleteValue delete value in singly linklist
+func (link *SinglyLink[T]) DeleteValue(value T) {
+	if link.Head == nil {
+		return
+	}
+	dummyHead := datastructure.NewLinkNode(value)
+	dummyHead.Next = link.Head
+	current := dummyHead
+
+	for current.Next != nil {
+		if reflect.DeepEqual(current.Next.Value, value) {
+			current.Next = current.Next.Next
+			link.length--
+		} else {
+			current = current.Next
+		}
+	}
+
+	link.Head = dummyHead.Next
+}
+
 // Reverse the linked list
 func (link *SinglyLink[T]) Reverse() {
 	var pre, next *datastructure.LinkNode[T]
--- a/datastructure/link/singlylink_test.go
+++ b/datastructure/link/singlylink_test.go
@@ -45,20 +45,28 @@ func TestSinglyLink_InsertAt(t *testing.T) {
 	assert.IsNotNil(err)

 	err = link.InsertAt(0, 1)
-	err = link.InsertAt(1, 2)
-	err = link.InsertAt(2, 4)
-	err = link.InsertAt(2, 3)
-
 	if err != nil {
 		t.FailNow()
 	}
+	err = link.InsertAt(1, 2)
+	if err != nil {
+		t.FailNow()
+	}
+	err = link.InsertAt(2, 4)
+	if err != nil {
+		t.FailNow()
+	}
+	err = link.InsertAt(2, 3)
+	if err != nil {
+		t.FailNow()
+	}
+
 	link.Print()

 	expected := []int{1, 2, 3, 4}
 	values := link.Values()

 	assert.Equal(expected, values)
-
 }

 func TestSinglyLink_DeleteAtHead(t *testing.T) {
@@ -103,6 +111,24 @@ func TestSinglyLink_DeleteAtTail(t *testing.T) {
 	assert.Equal(expected, values)
 }

+func TestSinglyLink_DeleteValue(t *testing.T) {
+	assert := internal.NewAssert(t, "TestSinglyLink_DeleteValue")
+
+	link := NewSinglyLink[int]()
+
+	link.InsertAtTail(1)
+	link.InsertAtTail(2)
+	link.InsertAtTail(2)
+	link.InsertAtTail(3)
+	link.InsertAtTail(4)
+
+	link.DeleteValue(2)
+	assert.Equal([]int{1, 3, 4}, link.Values())
+
+	link.DeleteValue(1)
+	assert.Equal([]int{3, 4}, link.Values())
+}
+
 func TestSinglyLink_DeleteAt(t *testing.T) {
 	assert := internal.NewAssert(t, "TestSinglyLink_DeleteAt")

--- a/datastructure/list/list_test.go
+++ b/datastructure/list/list_test.go
@@ -99,7 +99,7 @@ func TestPopFirst(t *testing.T) {
 	assert.Equal([]int{2, 3}, list.Data())

 	list2 := NewList([]int{})
-	v, ok = list2.PopFirst()
+	_, ok = list2.PopFirst()
 	assert.Equal(false, ok)
 	assert.Equal([]int{}, list2.Data())
 }
@@ -114,7 +114,7 @@ func TestPopLast(t *testing.T) {
 	assert.Equal([]int{1, 2}, list.Data())

 	list2 := NewList([]int{})
-	v, ok = list2.PopLast()
+	_, ok = list2.PopLast()
 	assert.Equal(false, ok)
 	assert.Equal([]int{}, list2.Data())
 }
--- a/datastructure/node.go
+++ b/datastructure/node.go
@@ -1,3 +1,7 @@
+// Copyright 2021 dudaodong@gmail.com. All rights reserved.
+// Use of this source code is governed by MIT license
+
+// Package datastructure implements some data structure. eg. list, linklist, stack, queue, tree, graph.
 package datastructure

 // LinkNode is a linkedlist node, which have a Value and Pre points to previous node, Next points to a next node of the link.
--- a/datastructure/queue/linkedqueue_test.go
+++ b/datastructure/queue/linkedqueue_test.go
@@ -40,14 +40,14 @@ func TestLinkedQueue_Front(t *testing.T) {
 	assert := internal.NewAssert(t, "TestLinkedQueue_Front")

 	queue := NewLinkedQueue[int]()
-	val, err := queue.Front()
+	_, err := queue.Front()
 	assert.IsNotNil(err)

 	queue.EnQueue(1)
 	queue.EnQueue(2)
 	queue.EnQueue(3)

-	val, err = queue.Front()
+	val, err := queue.Front()
 	assert.Equal(1, *val)
 	assert.IsNil(err)
 }
@@ -56,14 +56,14 @@ func TestLinkedQueue_Back(t *testing.T) {
 	assert := internal.NewAssert(t, "TestLinkedQueue_Back")

 	queue := NewLinkedQueue[int]()
-	val, err := queue.Back()
+	_, err := queue.Back()
 	assert.IsNotNil(err)

 	queue.EnQueue(1)
 	queue.EnQueue(2)
 	queue.EnQueue(3)

-	val, err = queue.Back()
+	val, err := queue.Back()
 	assert.Equal(3, *val)
 	assert.IsNil(err)
 }
--- a/datastructure/set/set.go
+++ b/datastructure/set/set.go
@@ -103,3 +103,34 @@ func (s Set[T]) Intersection(other Set[T]) Set[T] {

 	return set
 }
+
+// SymmetricDifference creates a new set whose element is in set1 or set2, but not in both sets
+func (s Set[T]) SymmetricDifference(other Set[T]) Set[T] {
+	set := NewSet[T]()
+	s.Iterate(func(value T) {
+		if !other.Contain(value) {
+			set.Add(value)
+		}
+	})
+
+	other.Iterate(func(value T) {
+		if !s.Contain(value) {
+			set.Add(value)
+		}
+	})
+
+	return set
+}
+
+// Minus creates an set of whose element in origin set but not in compared set
+func (s Set[T]) Minus(comparedSet Set[T]) Set[T] {
+	set := NewSet[T]()
+
+	s.Iterate(func(value T) {
+		if !comparedSet.Contain(value) {
+			set.Add(value)
+		}
+	})
+
+	return set
+}
--- a/datastructure/set/set_test.go
+++ b/datastructure/set/set_test.go
@@ -127,3 +127,23 @@ func TestSet_Intersection(t *testing.T) {

 	assert.Equal(expected, intersectionSet)
 }
+
+func TestSet_SymmetricDifference(t *testing.T) {
+	assert := internal.NewAssert(t, "TestSet_SymmetricDifference")
+
+	set1 := NewSet(1, 2, 3)
+	set2 := NewSet(2, 3, 4, 5)
+
+	assert.Equal(NewSet(1, 4, 5), set1.SymmetricDifference(set2))
+}
+
+func TestSet_Minus(t *testing.T) {
+	assert := internal.NewAssert(t, "TestSet_Minus")
+
+	set1 := NewSet(1, 2, 3)
+	set2 := NewSet(2, 3, 4, 5)
+	set3 := NewSet(2, 3)
+
+	assert.Equal(NewSet(1), set1.Minus(set2))
+	assert.Equal(NewSet(4, 5), set2.Minus(set3))
+}
--- a/datastructure/stack/arraystack_test.go
+++ b/datastructure/stack/arraystack_test.go
@@ -26,14 +26,14 @@ func TestArrayStack_Pop(t *testing.T) {
 	assert := internal.NewAssert(t, "TestArrayStack_Pop")

 	stack := NewArrayStack[int]()
-	topItem, err := stack.Pop()
+	_, err := stack.Pop()
 	assert.IsNotNil(err)

 	stack.Push(1)
 	stack.Push(2)
 	stack.Push(3)

-	topItem, err = stack.Pop()
+	topItem, err := stack.Pop()
 	assert.IsNil(err)
 	assert.Equal(3, *topItem)

@@ -45,14 +45,14 @@ func TestArrayStack_Peak(t *testing.T) {
 	assert := internal.NewAssert(t, "TestArrayStack_Peak")

 	stack := NewArrayStack[int]()
-	topItem, err := stack.Peak()
+	_, err := stack.Peak()
 	assert.IsNotNil(err)

 	stack.Push(1)
 	stack.Push(2)
 	stack.Push(3)

-	topItem, err = stack.Peak()
+	topItem, err := stack.Peak()
 	assert.IsNil(err)
 	assert.Equal(3, *topItem)

--- a/datastructure/stack/linkedstack_test.go
+++ b/datastructure/stack/linkedstack_test.go
@@ -28,14 +28,14 @@ func TestLinkedStack_Pop(t *testing.T) {
 	assert := internal.NewAssert(t, "TestLinkedStack_Pop")

 	stack := NewLinkedStack[int]()
-	topItem, err := stack.Pop()
+	_, err := stack.Pop()
 	assert.IsNotNil(err)

 	stack.Push(1)
 	stack.Push(2)
 	stack.Push(3)

-	topItem, err = stack.Pop()
+	topItem, err := stack.Pop()
 	assert.IsNil(err)
 	assert.Equal(3, *topItem)

@@ -48,14 +48,14 @@ func TestLinkedStack_Peak(t *testing.T) {
 	assert := internal.NewAssert(t, "TestLinkedStack_Peak")

 	stack := NewLinkedStack[int]()
-	topItem, err := stack.Peak()
+	_, err := stack.Peak()
 	assert.IsNotNil(err)

 	stack.Push(1)
 	stack.Push(2)
 	stack.Push(3)

-	topItem, err = stack.Peak()
+	topItem, err := stack.Peak()
 	assert.IsNil(err)
 	assert.Equal(3, *topItem)

--- a/datetime/conversion.go
+++ b/datetime/conversion.go
@@ -0,0 +1,60 @@
+// Copyright 2021 dudaodong@gmail.com. All rights reserved.
+// Use of this source code is governed by MIT license.
+
+package datetime
+
+import "time"
+
+type theTime struct {
+	unix int64
+}
+
+// NewUnixNow return unix timestamp of current time
+func NewUnixNow() *theTime {
+	return &theTime{unix: time.Now().Unix()}
+}
+
+// NewUnix return unix timestamp of specified time
+func NewUnix(unix int64) *theTime {
+	return &theTime{unix: unix}
+}
+
+// NewFormat return unix timestamp of specified time string, t should be "yyyy-mm-dd hh:mm:ss"
+func NewFormat(t string) (*theTime, error) {
+	timeLayout := "2006-01-02 15:04:05"
+	loc := time.FixedZone("CST", 8*3600)
+	tt, err := time.ParseInLocation(timeLayout, t, loc)
+	if err != nil {
+		return nil, err
+	}
+	return &theTime{unix: tt.Unix()}, nil
+}
+
+// NewISO8601 return unix timestamp of specified iso8601 time string
+func NewISO8601(iso8601 string) (*theTime, error) {
+	t, err := time.ParseInLocation(time.RFC3339, iso8601, time.UTC)
+	if err != nil {
+		return nil, err
+	}
+	return &theTime{unix: t.Unix()}, nil
+}
+
+// ToUnix return unix timestamp
+func (t *theTime) ToUnix() int64 {
+	return t.unix
+}
+
+// ToFormat return the time string 'yyyy-mm-dd hh:mm:ss' of unix time
+func (t *theTime) ToFormat() string {
+	return time.Unix(t.unix, 0).Format("2006-01-02 15:04:05")
+}
+
+// ToFormatForTpl return the time string which format is specified tpl
+func (t *theTime) ToFormatForTpl(tpl string) string {
+	return time.Unix(t.unix, 0).Format(tpl)
+}
+
+// ToFormatForTpl return iso8601 time string
+func (t *theTime) ToIso8601() string {
+	return time.Unix(t.unix, 0).Format(time.RFC3339)
+}
--- a/datetime/conversion_test.go
+++ b/datetime/conversion_test.go
@@ -0,0 +1,53 @@
+package datetime
+
+import (
+	"testing"
+
+	"github.com/duke-git/lancet/v2/internal"
+)
+
+func TestToUnix(t *testing.T) {
+	assert := internal.NewAssert(t, "TestToUnix")
+
+	tm1 := NewUnixNow()
+	unixTimestamp := tm1.ToUnix()
+	tm2 := NewUnix(unixTimestamp)
+
+	assert.Equal(tm1, tm2)
+}
+
+func TestToFormat(t *testing.T) {
+	assert := internal.NewAssert(t, "TestToFormat")
+
+	_, err := NewFormat("2022/03/18 17:04:05")
+	assert.IsNotNil(err)
+
+	tm, err := NewFormat("2022-03-18 17:04:05")
+	assert.IsNil(err)
+
+	t.Log("ToFormat -> ", tm.ToFormat())
+}
+
+func TestToFormatForTpl(t *testing.T) {
+	assert := internal.NewAssert(t, "TestToFormatForTpl")
+
+	_, err := NewFormat("2022/03/18 17:04:05")
+	assert.IsNotNil(err)
+
+	tm, err := NewFormat("2022-03-18 17:04:05")
+	assert.IsNil(err)
+
+	t.Log("ToFormatForTpl -> ", tm.ToFormatForTpl("2006/01/02 15:04:05"))
+}
+
+func TestToIso8601(t *testing.T) {
+	assert := internal.NewAssert(t, "TestToIso8601")
+
+	_, err := NewISO8601("2022-03-18 17:04:05")
+	assert.IsNotNil(err)
+
+	tm, err := NewISO8601("2006-01-02T15:04:05.999Z")
+	assert.IsNil(err)
+
+	t.Log("ToIso8601 -> ", tm.ToIso8601())
+}
--- a/docs/datetime.md
+++ b/docs/datetime.md
@@ -6,6 +6,7 @@ Package datetime supports date and time format and compare.
 ## Source:

 - [https://github.com/duke-git/lancet/blob/main/datetime/datetime.go](https://github.com/duke-git/lancet/blob/main/datetime/datetime.go)
+- [https://github.com/duke-git/lancet/blob/main/datetime/conversion.go](https://github.com/duke-git/lancet/blob/main/datetime/conversion.go)

 <div STYLE="page-break-after: always;"></div>

@@ -28,7 +29,6 @@ import (
 - [BeginOfWeek](#BeginOfWeek)
 - [BeginOfMonth](#BeginOfMonth)
 - [BeginOfYear](#BeginOfYear)
-
 - [EndOfMinute](#EndOfMinute)
 - [EndOfHour](#EndOfHour)
 - [EndOfDay](#EndOfDay)
@@ -41,9 +41,19 @@ import (
 - [GetZeroHourTimestamp](#GetZeroHourTimestamp)
 - [GetNightTimestamp](#GetNightTimestamp)
 - [FormatTimeToStr](#FormatTimeToStr)
-
 - [FormatStrToTime](#FormatStrToTime)

+- [NewUnixNow](#NewUnixNow)
+- [NewUnix](#NewUnix)
+- [NewFormat](#NewFormat)
+- [NewISO8601](#NewISO8601)
+- [ToUnix](#ToUnix)
+- [ToFormat](#ToFormat)
+- [ToFormatForTpl](#ToFormatForTpl)
+- [ToIso8601](#ToIso8601)
+
+
+
 <div STYLE="page-break-after: always;"></div>

 ## Documentation
@@ -667,3 +677,221 @@ func main() {



+### <span id="NewUnixNow">NewUnixNow</span>
+<p>Return unix timestamp of current time</p>
+
+<b>Signature:</b>
+
+```go
+type theTime struct {
+	unix int64
+}
+func NewUnixNow() *theTime
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/datetime"
+)
+
+func main() {
+    tm := datetime.NewUnixNow()
+    fmt.Println(tm) //&{1647597438}
+}
+```
+
+
+### <span id="NewUnix">NewUnix</span>
+<p>Return unix timestamp of specified int64 value.</p>
+
+<b>Signature:</b>
+
+```go
+type theTime struct {
+	unix int64
+}
+func NewUnix(unix int64) *theTime
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/datetime"
+)
+
+func main() {
+    tm := datetime.NewUnix(1647597438)
+    fmt.Println(tm) //&{1647597438}
+}
+```
+
+
+
+### <span id="NewFormat">NewFormat</span>
+<p>Return unix timestamp of specified time string, t should be "yyyy-mm-dd hh:mm:ss".</p>
+
+<b>Signature:</b>
+
+```go
+type theTime struct {
+	unix int64
+}
+func NewFormat(t string) (*theTime, error)
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/datetime"
+)
+
+func main() {
+    tm, err := datetime.NewFormat("2022-03-18 17:04:05")
+    fmt.Println(tm) //&{1647594245}
+}
+```
+
+
+
+
+### <span id="NewISO8601">NewISO8601</span>
+<p>Return unix timestamp of specified iso8601 time string.</p>
+
+<b>Signature:</b>
+
+```go
+type theTime struct {
+	unix int64
+}
+func NewISO8601(iso8601 string) (*theTime, error)
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/datetime"
+)
+
+func main() {
+    tm, err := datetime.NewISO8601("2006-01-02T15:04:05.999Z")
+    fmt.Println(tm) //&{1136214245}
+}
+```
+
+
+
+### <span id="ToUnix">ToUnix</span>
+<p>Return unix timestamp.</p>
+
+<b>Signature:</b>
+
+```go
+func (t *theTime) ToUnix() int64
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/datetime"
+)
+
+func main() {
+    tm := datetime.NewUnixNow()
+    fmt.Println(tm.ToUnix()) //1647597438
+}
+```
+
+
+
+### <span id="ToFormat">ToFormat</span>
+<p>Return time string 'yyyy-mm-dd hh:mm:ss'.</p>
+
+<b>Signature:</b>
+
+```go
+func (t *theTime) ToFormat() string
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/datetime"
+)
+
+func main() {
+    tm, _ := datetime.NewFormat("2022-03-18 17:04:05")
+    fmt.Println(tm.ToFormat()) //"2022-03-18 17:04:05"
+}
+```
+
+
+
+### <span id="ToFormatForTpl">ToFormatForTpl</span>
+<p>Return the time string which format is specified tpl.</p>
+
+<b>Signature:</b>
+
+```go
+func (t *theTime) ToFormatForTpl(tpl string) string
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/datetime"
+)
+
+func main() {
+    tm, _ := datetime.NewFormat("2022-03-18 17:04:05")
+    ts := tm.ToFormatForTpl("2006/01/02 15:04:05")
+    fmt.Println(ts) //"2022/03/18 17:04:05"
+}
+```
+
+
+### <span id="ToIso8601">ToIso8601</span>
+<p>Return iso8601 time string.</p>
+
+<b>Signature:</b>
+
+```go
+func (t *theTime) ToIso8601() string
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/datetime"
+)
+
+func main() {
+    tm, _ := datetime.NewISO8601("2006-01-02T15:04:05.999Z")
+    ts := tm.ToIso8601()
+    fmt.Println(ts) //"2006-01-02T23:04:05+08:00"
+}
+```
--- a/docs/datetime_zh-CN.md
+++ b/docs/datetime_zh-CN.md
@@ -28,7 +28,6 @@ import (
 - [BeginOfWeek](#BeginOfWeek)
 - [BeginOfMonth](#BeginOfMonth)
 - [BeginOfYear](#BeginOfYear)
-
 - [EndOfMinute](#EndOfMinute)
 - [EndOfHour](#EndOfHour)
 - [EndOfDay](#EndOfDay)
@@ -43,6 +42,15 @@ import (
 - [FormatTimeToStr](#FormatTimeToStr)
 - [FormatStrToTime](#FormatStrToTime)

+- [NewUnixNow](#NewUnixNow)
+- [NewUnix](#NewUnix)
+- [NewFormat](#NewFormat)
+- [NewISO8601](#NewISO8601)
+- [ToUnix](#ToUnix)
+- [ToFormat](#ToFormat)
+- [ToFormatForTpl](#ToFormatForTpl)
+- [ToIso8601](#ToIso8601)
+
 <div STYLE="page-break-after: always;"></div>

 ## 文档
@@ -665,4 +673,221 @@ func main() {
 ```


+### <span id="NewUnixNow">NewUnixNow</span>
+<p>创建一个当前时间的unix时间戳</p>

+<b>函数签名:</b>
+
+```go
+type theTime struct {
+	unix int64
+}
+func NewUnixNow() *theTime
+```
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/datetime"
+)
+
+func main() {
+    tm := datetime.NewUnixNow()
+    fmt.Println(tm) //&{1647597438}
+}
+```
+
+
+### <span id="NewUnix">NewUnix</span>
+<p>创建一个unix时间戳</p>
+
+<b>函数签名:</b>
+
+```go
+type theTime struct {
+	unix int64
+}
+func NewUnix(unix int64) *theTime
+```
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/datetime"
+)
+
+func main() {
+    tm := datetime.NewUnix(1647597438)
+    fmt.Println(tm) //&{1647597438}
+}
+```
+
+
+
+### <span id="NewFormat">NewFormat</span>
+<p>创建一个yyyy-mm-dd hh:mm:ss格式时间字符串的unix时间戳</p>
+
+<b>函数签名:</b>
+
+```go
+type theTime struct {
+	unix int64
+}
+func NewFormat(t string) (*theTime, error)
+```
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/datetime"
+)
+
+func main() {
+    tm, err := datetime.NewFormat("2022-03-18 17:04:05")
+    fmt.Println(tm) //&{1647594245}
+}
+```
+
+
+
+
+### <span id="NewISO8601">NewISO8601</span>
+<p>创建一个iso8601格式时间字符串的unix时间戳</p>
+
+<b>函数签名:</b>
+
+```go
+type theTime struct {
+	unix int64
+}
+func NewISO8601(iso8601 string) (*theTime, error)
+```
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/datetime"
+)
+
+func main() {
+    tm, err := datetime.NewISO8601("2006-01-02T15:04:05.999Z")
+    fmt.Println(tm) //&{1136214245}
+}
+```
+
+
+
+### <span id="ToUnix">ToUnix</span>
+<p>返回unix时间戳</p>
+
+<b>函数签名:</b>
+
+```go
+func (t *theTime) ToUnix() int64
+```
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/datetime"
+)
+
+func main() {
+    tm := datetime.NewUnixNow()
+    fmt.Println(tm.ToUnix()) //1647597438
+}
+```
+
+
+
+### <span id="ToFormat">ToFormat</span>
+<p>返回格式'yyyy-mm-dd hh:mm:ss'的日期字符串</p>
+
+<b>函数签名:</b>
+
+```go
+func (t *theTime) ToFormat() string
+```
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/datetime"
+)
+
+func main() {
+    tm, _ := datetime.NewFormat("2022-03-18 17:04:05")
+    fmt.Println(tm.ToFormat()) //"2022-03-18 17:04:05"
+}
+```
+
+
+
+### <span id="ToFormatForTpl">ToFormatForTpl</span>
+<p>返回tpl格式指定的日期字符串</p>
+
+<b>函数签名:</b>
+
+```go
+func (t *theTime) ToFormatForTpl(tpl string) string
+```
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/datetime"
+)
+
+func main() {
+    tm, _ := datetime.NewFormat("2022-03-18 17:04:05")
+    ts := tm.ToFormatForTpl("2006/01/02 15:04:05")
+    fmt.Println(ts) //"2022/03/18 17:04:05"
+}
+```
+
+
+### <span id="ToIso8601">ToIso8601</span>
+<p>返回iso8601日期字符串</p>
+
+<b>函数签名:</b>
+
+```go
+func (t *theTime) ToIso8601() string
+```
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/datetime"
+)
+
+func main() {
+    tm, _ := datetime.NewISO8601("2006-01-02T15:04:05.999Z")
+    ts := tm.ToIso8601()
+    fmt.Println(ts) //"2006-01-02T23:04:05+08:00"
+}
+```
--- a/docs/maputil.md
+++ b/docs/maputil.md
@@ -0,0 +1,304 @@
+# Maputil
+Package maputil includes some functions to manipulate map.
+
+<div STYLE="page-break-after: always;"></div>
+
+## Source:
+
+- [https://github.com/duke-git/lancet/blob/main/maputil/maputil.go](https://github.com/duke-git/lancet/blob/main/maputil/maputil.go)
+
+
+<div STYLE="page-break-after: always;"></div>
+
+## Example:
+```go
+import (
+    "github.com/duke-git/lancet/v2/maputil"
+)
+```
+
+<div STYLE="page-break-after: always;"></div>
+
+## Index
+- [ForEach](#ForEach)
+- [Filter](#Filter)
+- [Intersect](#Intersect)
+- [Keys](#Keys)
+- [Merge](#Merge)
+- [Minus](#Minus)
+- [Values](#Values)
+
+<div STYLE="page-break-after: always;"></div>
+
+## Documentation
+
+
+
+### <span id="ForEach">ForEach</span>
+<p>Executes iteratee funcation for every key and value pair in map.</p>
+
+<b>Signature:</b>
+
+```go
+func ForEach[K comparable, V any](m map[K]V, iteratee func(key K, value V))
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+		"d": 4,
+	}
+
+	var sum int
+
+	maputil.ForEach(m, func(_ string, value int) {
+		sum += value
+	})
+	fmt.Println(sum) // 10
+}
+```
+
+
+
+
+### <span id="Filter">Filter</span>
+<p>Iterates over map, return a new map contains all key and value pairs pass the predicate function.</p>
+
+<b>Signature:</b>
+
+```go
+func Filter[K comparable, V any](m map[K]V, predicate func(key K, value V) bool) map[K]V
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+		"d": 4,
+		"e": 5,
+	}
+	isEven := func(_ string, value int) bool {
+		return value%2 == 0
+	}
+
+	maputil.Filter(m, func(_ string, value int) {
+		sum += value
+	})
+	res := maputil.Filter(m, isEven)
+	fmt.Println(res) // map[string]int{"b": 2, "d": 4,}
+}
+```
+
+
+
+
+### <span id="Intersect">Intersect</span>
+<p>Iterates over maps, return a new map of key and value pairs in all given maps.</p>
+
+<b>Signature:</b>
+
+```go
+func Intersect[K comparable, V any](maps ...map[K]V) map[K]V
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+	m1 := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+	}
+
+	m2 := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 6,
+		"d": 7,
+	}
+
+	m3 := map[string]int{
+		"a": 1,
+		"b": 9,
+		"e": 9,
+	}
+
+	fmt.Println(maputil.Intersect(m1)) // map[string]int{"a": 1, "b": 2, "c": 3}
+
+	fmt.Println(maputil.Intersect(m1, m2)) // map[string]int{"a": 1, "b": 2}
+
+	fmt.Println(maputil.Intersect(m1, m2, m3)) // map[string]int{"a": 1}
+}
+```
+
+
+
+
+### <span id="Keys">Keys</span>
+<p>Returns a slice of the map's keys.</p>
+
+<b>Signature:</b>
+
+```go
+func Keys[K comparable, V any](m map[K]V) []K
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+	m := map[int]string{
+		1: "a",
+		2: "a",
+		3: "b",
+		4: "c",
+		5: "d",
+	}
+
+	keys := maputil.Keys(m)
+	sort.Ints(keys)
+	fmt.Println(keys) // []int{1, 2, 3, 4, 5}
+}
+```
+
+
+
+
+### <span id="Merge">Merge</span>
+<p>Merge maps, next key will overwrite previous key.</p>
+
+<b>Signature:</b>
+
+```go
+func Merge[K comparable, V any](maps ...map[K]V) map[K]V
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+	m1 := map[int]string{
+		1: "a",
+		2: "b",
+	}
+	m2 := map[int]string{
+		1: "1",
+		3: "2",
+	}
+	fmt.Println(maputil.Merge(m1, m2)) // map[int]string{1:"1", 2:"b", 3:"2",}
+}
+```
+
+
+
+
+### <span id="Minus">Minus</span>
+<p>Creates an map of whose key in mapA but not in mapB.</p>
+
+<b>Signature:</b>
+
+```go
+func Minus[K comparable, V any](mapA, mapB map[K]V) map[K]V
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+	m1 := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+	}
+
+	m2 := map[string]int{
+		"a": 11,
+		"b": 22,
+		"d": 33,
+	}
+
+	fmt.Println(maputil.Minus(m1, m2)) //map[string]int{"c": 3}
+}
+```
+
+
+
+### <span id="Values">Values</span>
+<p>Returns a slice of the map's values.</p>
+
+<b>Signature:</b>
+
+```go
+func Values[K comparable, V any](m map[K]V) []V
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+	m := map[int]string{
+		1: "a",
+		2: "a",
+		3: "b",
+		4: "c",
+		5: "d",
+	}
+
+	values := maputil.Values(m)
+	sort.Strings(values)
+
+	fmt.Println(values) // []string{"a", "a", "b", "c", "d"}
+}
+```
--- a/docs/maputil_zh-CN.md
+++ b/docs/maputil_zh-CN.md
@@ -0,0 +1,304 @@
+# Maputil
+maputil包包括一些操作map的函数。
+
+<div STYLE="page-break-after: always;"></div>
+
+## 源码:
+
+- [https://github.com/duke-git/lancet/blob/main/maputil/maputil.go](https://github.com/duke-git/lancet/blob/main/maputil/maputil.go)
+
+
+<div STYLE="page-break-after: always;"></div>
+
+## 用法:
+```go
+import (
+    "github.com/duke-git/lancet/v2/maputil"
+)
+```
+
+<div STYLE="page-break-after: always;"></div>
+
+## 目录:
+- [ForEach](#ForEach)
+- [Filter](#Filter)
+- [Intersect](#Intersect)
+- [Keys](#Keys)
+- [Merge](#Merge)
+- [Minus](#Minus)
+- [Values](#Values)
+
+<div STYLE="page-break-after: always;"></div>
+
+## API文档:
+
+
+
+### <span id="ForEach">ForEach</span>
+<p>对map中的每对key和value执行iteratee函数</p>
+
+<b>函数签名:</b>
+
+```go
+func ForEach[K comparable, V any](m map[K]V, iteratee func(key K, value V))
+```
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+		"d": 4,
+	}
+
+	var sum int
+
+	maputil.ForEach(m, func(_ string, value int) {
+		sum += value
+	})
+	fmt.Println(sum) // 10
+}
+```
+
+
+
+
+### <span id="Filter">Filter</span>
+<p>迭代map中的每对key和value, 返回符合predicate函数的key, value</p>
+
+<b>函数签名:</b>
+
+```go
+func Filter[K comparable, V any](m map[K]V, predicate func(key K, value V) bool) map[K]V
+```
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+		"d": 4,
+		"e": 5,
+	}
+	isEven := func(_ string, value int) bool {
+		return value%2 == 0
+	}
+
+	maputil.Filter(m, func(_ string, value int) {
+		sum += value
+	})
+	res := maputil.Filter(m, isEven)
+	fmt.Println(res) // map[string]int{"b": 2, "d": 4,}
+}
+```
+
+
+
+
+### <span id="Intersect">Intersect</span>
+<p>多个map的交集操作</p>
+
+<b>函数签名:</b>
+
+```go
+func Intersect[K comparable, V any](maps ...map[K]V) map[K]V
+```
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+	m1 := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+	}
+
+	m2 := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 6,
+		"d": 7,
+	}
+
+	m3 := map[string]int{
+		"a": 1,
+		"b": 9,
+		"e": 9,
+	}
+
+	fmt.Println(maputil.Intersect(m1)) // map[string]int{"a": 1, "b": 2, "c": 3}
+
+	fmt.Println(maputil.Intersect(m1, m2)) // map[string]int{"a": 1, "b": 2}
+
+	fmt.Println(maputil.Intersect(m1, m2, m3)) // map[string]int{"a": 1}
+}
+```
+
+
+
+
+### <span id="Keys">Keys</span>
+<p>返回map中所有key的切片</p>
+
+<b>函数签名:</b>
+
+```go
+func Keys[K comparable, V any](m map[K]V) []K
+```
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+	m := map[int]string{
+		1: "a",
+		2: "a",
+		3: "b",
+		4: "c",
+		5: "d",
+	}
+
+	keys := maputil.Keys(m)
+	sort.Ints(keys)
+	fmt.Println(keys) // []int{1, 2, 3, 4, 5}
+}
+```
+
+
+
+
+### <span id="Merge">Merge</span>
+<p>合并多个maps, 相同的key会被后来的key覆盖</p>
+
+<b>函数签名:</b>
+
+```go
+func Merge[K comparable, V any](maps ...map[K]V) map[K]V
+```
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+	m1 := map[int]string{
+		1: "a",
+		2: "b",
+	}
+	m2 := map[int]string{
+		1: "1",
+		3: "2",
+	}
+	fmt.Println(maputil.Merge(m1, m2)) // map[int]string{1:"1", 2:"b", 3:"2",}
+}
+```
+
+
+
+
+### <span id="Minus">Minus</span>
+<p>返回一个map，其中的key存在于mapA，不存在于mapB.</p>
+
+<b>函数签名:</b>
+
+```go
+func Minus[K comparable, V any](mapA, mapB map[K]V) map[K]V
+```
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+	m1 := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+	}
+
+	m2 := map[string]int{
+		"a": 11,
+		"b": 22,
+		"d": 33,
+	}
+
+	fmt.Println(maputil.Minus(m1, m2)) //map[string]int{"c": 3}
+}
+```
+
+
+
+### <span id="Values">Values</span>
+<p>返回map中所有value的切片</p>
+
+<b>函数签名:</b>
+
+```go
+func Values[K comparable, V any](m map[K]V) []V
+```
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+	m := map[int]string{
+		1: "a",
+		2: "a",
+		3: "b",
+		4: "c",
+		5: "d",
+	}
+
+	values := maputil.Values(m)
+	sort.Strings(values)
+
+	fmt.Println(values) // []string{"a", "a", "b", "c", "d"}
+}
+```
--- a/docs/mathutil.md
+++ b/docs/mathutil.md
@@ -20,9 +20,13 @@ import (
 <div STYLE="page-break-after: always;"></div>

 ## Index
+- [Average](#Average)
 - [Exponent](#Exponent)
 - [Fibonacci](#Fibonacci)
 - [Factorial](#Factorial)
+- [Max](#Max)
+- [Min](#Min)
+
 - [Percent](#Percent)
 - [RoundToFloat](#RoundToFloat)
 - [RoundToString](#RoundToString)
@@ -33,6 +37,35 @@ import (
 ## Documentation


+
+### <span id="Average">Average</span>
+<p>Return average value of numbers. Maybe call RoundToFloat to round result.</p>
+
+<b>Signature:</b>
+
+```go
+func Average[T lancetconstraints.Number](numbers ...T) T
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/mathutil"
+)
+
+func main() {
+	fmt.Println(mathutil.Average(0, 0)) //0
+	fmt.Println(mathutil.Average(1, 1)) //1
+	avg := mathutil.Average(1.2, 1.4) //1.2999999998
+	roundAvg := mmathutil.RoundToFloat(avg, 1) // 1.3
+}
+```
+
+
+
 ### <span id="Exponent">Exponent</span>
 <p>Calculate x to the nth power.</p>

@@ -117,6 +150,60 @@ func main() {



+### <span id="Max">Max</span>
+<p>Return max value of numbers.</p>
+
+<b>Signature:</b>
+
+```go
+func Max[T lancetconstraints.Number](numbers ...T) T
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/mathutil"
+)
+
+func main() {
+	fmt.Println(mathutil.Max(0, 0)) //0
+	fmt.Println(mathutil.Max(1, 2, 3)) //3
+	fmt.Println(mathutil.Max(1.2, 1.4, 1.1, 1.4)) //1.4
+}
+```
+
+
+
+### <span id="Min">Min</span>
+<p>Return min value of numbers.</p>
+
+<b>Signature:</b>
+
+```go
+func Min[T lancetconstraints.Number](numbers ...T) T
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/mathutil"
+)
+
+func main() {
+	fmt.Println(mathutil.Min(0, 0)) //0
+	fmt.Println(mathutil.Min(1, 2, 3)) //1
+	fmt.Println(mathutil.Min(1.2, 1.4, 1.1, 1.4)) //1.1
+}
+```
+
+
+
 ### <span id="Percent">Percent</span>
 <p>calculate the percentage of val to total, retain n decimal places.</p>

--- a/docs/mathutil_zh-CN.md
+++ b/docs/mathutil_zh-CN.md
@@ -20,10 +20,13 @@ import (
 <div STYLE="page-break-after: always;"></div>

 ## 目录
+- [Average](#Average)
 - [Exponent](#Exponent)
 - [Fibonacci](#Fibonacci)
 - [Factorial](#Factorial)
-
+- [Max](#Max)
+- [Min](#Min)
+  
 - [Percent](#Percent)
 - [RoundToFloat](#RoundToFloat)
 - [RoundToString](#RoundToString)
@@ -34,6 +37,33 @@ import (
 ## Documentation


+### <span id="Average">Average</span>
+<p>计算平均数. 可能需要对结果调用RoundToFloat方法四舍五入</p>
+
+<b>函数签名:</b>
+
+```go
+func Average[T lancetconstraints.Number](numbers ...T) T
+```
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/mathutil"
+)
+
+func main() {
+	fmt.Println(mathutil.Average(0, 0)) //0
+	fmt.Println(mathutil.Average(1, 1)) //1
+	avg := mathutil.Average(1.2, 1.4) //1.2999999998
+	roundAvg := mmathutil.RoundToFloat(avg, 1) // 1.3
+}
+```
+
+
 ### <span id="Exponent">Exponent</span>
 <p>指数计算（x的n次方）</p>

@@ -117,6 +147,59 @@ func main() {
 ```


+### <span id="Max">Max</span>
+<p>返回参数中的最大数</p>
+
+<b>函数签名:</b>
+
+```go
+func Max[T lancetconstraints.Number](numbers ...T) T
+```
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/mathutil"
+)
+
+func main() {
+	fmt.Println(mathutil.Max(0, 0)) //0
+	fmt.Println(mathutil.Max(1, 2, 3)) //3
+	fmt.Println(mathutil.Max(1.2, 1.4, 1.1, 1.4)) //1.4
+}
+```
+
+
+
+### <span id="Min">Min</span>
+<p>返回参数中的最小数</p>
+
+<b>函数签名:</b>
+
+```go
+func Min[T lancetconstraints.Number](numbers ...T) T
+```
+<b>例子:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/mathutil"
+)
+
+func main() {
+	fmt.Println(mathutil.Min(0, 0)) //0
+	fmt.Println(mathutil.Min(1, 2, 3)) //1
+	fmt.Println(mathutil.Min(1.2, 1.4, 1.1, 1.4)) //1.1
+}
+```
+
+

 ### <span id="Percent">Percent</span>
 <p>计算百分比，保留n位小数</p>
--- a/docs/slice.md
+++ b/docs/slice.md
@@ -37,8 +37,9 @@ import (
 - [FindLast](#FindLast)
 - [FlattenDeep](#FlattenDeep)
 - [ForEach](#ForEach)
-  
+
 - [GroupBy](#GroupBy)
+- [GroupWith](#GroupWith)
 - [IntSlice](#IntSlice)
 - [InterfaceSlice](#InterfaceSlice)
 - [Intersection](#Intersection)
@@ -50,6 +51,7 @@ import (
 - [SortByField](#SortByField)
 - [Some](#Some)
 - [StringSlice](#StringSlice)
+- [SymmetricDifference](#SymmetricDifference)
 - [Unique](#Unique)
 - [Union](#Union)
 - [UpdateAt](#UpdateAt)
@@ -564,6 +566,34 @@ func main() {



+### <span id="GroupWith">GroupWith</span>
+<p>Return a map composed of keys generated from the results of running each element of slice thru iteratee.</p>
+
+<b>Signature:</b>
+
+```go
+func GroupWith[T any, U comparable](slice []T, iteratee func(T) U) map[U][]T 
+```
+<b>Example:</b>
+
+```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)
+	}
+	res := slice.GroupWith(nums, floor)
+	fmt.Println(res) //map[float64][]float64{ 4: {4.2}, 6: {6.1, 6.3},}
+}
+```
+
+
+
 ### <span id="IntSlice">IntSlice</span>
 <p>Convert interface slice to int slice.</p>

@@ -880,6 +910,35 @@ func main() {



+### <span id="SymmetricDifference">SymmetricDifference</span>
+<p>Create a slice whose element is in given slices, but not in both slices.</p>
+
+<b>Signature:</b>
+
+```go
+func SymmetricDifference[T any](slices ...[]T) []T
+```
+<b>Example:</b>
+
+```go
+import (
+	"fmt"
+	"github.com/duke-git/lancet/v2/slice"
+)
+
+func main() {
+	s1 := []int{1, 2, 3}
+	s2 := []int{1, 2, 4}
+	s3 := []int{1, 2, 3, 5}
+
+	fmt.Println(slice.SymmetricDifference(s1)) //[]int{1, 2, 3}
+	fmt.Println(slice.SymmetricDifference(s1, s2)) //[]int{3, 4}
+	fmt.Println(slice.SymmetricDifference(s1, s2, s3)) //[]int{3, 4, 5}
+}
+```
+
+
+
 ### <span id="Unique">Unique</span>
 <p>Remove duplicate elements in slice.</p>

--- a/docs/slice_zh-CN.md
+++ b/docs/slice_zh-CN.md
@@ -39,6 +39,7 @@ import (
 - [ForEach](#ForEach)
  
 - [GroupBy](#GroupBy)
+- [GroupWith](#GroupWith)
 - [IntSlice](#IntSlice)
 - [InterfaceSlice](#InterfaceSlice)
 - [Intersection](#Intersection)
@@ -50,6 +51,7 @@ import (
 - [SortByField](#SortByField)
 - [Some](#Some)
 - [StringSlice](#StringSlice)
+- [SymmetricDifference](#SymmetricDifference)
 - [Unique](#Unique)
 - [Union](#Union)
 - [UpdateAt](#UpdateAt)
@@ -565,6 +567,32 @@ func main() {



+### <span id="GroupWith">GroupWith</span>
+<p>创建一个map，key是iteratee遍历slice中的每个元素返回的结果。 分组值的顺序是由他们出现在slice中的顺序确定的。每个键对应的值负责生成key的元素组成的数组。iteratee调用1个参数： (value)</p>
+
+<b>函数签名:</b>
+
+```go
+func GroupWith[T any, U comparable](slice []T, iteratee func(T) U) map[U][]T 
+```
+<b>例子:</b>
+
+```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)
+	}
+	res := slice.GroupWith(nums, floor)
+	fmt.Println(res) //map[float64][]float64{ 4: {4.2}, 6: {6.1, 6.3},}
+}
+```
+

 ### <span id="IntSlice">IntSlice</span>
 <p>将接口切片转换为int切片</p>
@@ -882,6 +910,34 @@ func main() {



+### <span id="SymmetricDifference">SymmetricDifference</span>
+<p>返回一个切片，其中的元素存在于参数切片中，但不同时存储在于参数切片中（交集取反）</p>
+
+<b>函数签名:</b>
+
+```go
+func SymmetricDifference[T any](slices ...[]T) []T
+```
+<b>例子:</b>
+
+```go
+import (
+	"fmt"
+	"github.com/duke-git/lancet/v2/slice"
+)
+
+func main() {
+	s1 := []int{1, 2, 3}
+	s2 := []int{1, 2, 4}
+	s3 := []int{1, 2, 3, 5}
+
+	fmt.Println(slice.SymmetricDifference(s1)) //[]int{1, 2, 3}
+	fmt.Println(slice.SymmetricDifference(s1, s2)) //[]int{3, 4}
+	fmt.Println(slice.SymmetricDifference(s1, s2, s3)) //[]int{3, 4, 5}
+}
+```
+
+
 ### <span id="Unique">Unique</span>
 <p>删除切片中的重复元素</p>

--- a/fileutil/file_test.go
+++ b/fileutil/file_test.go
@@ -76,10 +76,10 @@ func TestCopyFile(t *testing.T) {
 func TestListFileNames(t *testing.T) {
 	assert := internal.NewAssert(t, "TestListFileNames")

-	filesInPath, err := ListFileNames("../datetime/")
+	filesInPath, err := ListFileNames("./")
 	assert.IsNil(err)

-	expected := []string{"datetime.go", "datetime_test.go"}
+	expected := []string{"file.go", "file_test.go"}
 	assert.Equal(expected, filesInPath)
 }

--- a/lancetconstraints/constraints.go
+++ b/lancetconstraints/constraints.go
@@ -11,3 +11,8 @@ type Comparator interface {
 	// Descending order: should return 1 -> v1 < v2, 0 -> v1 = v2, -1 -> v1 > v2
 	Compare(v1, v2 any) int
 }
+
+// Number contains all types of number and uintptr, used for generics constraint
+type Number interface {
+	int | int8 | int16 | int32 | int64 | uint | uint8 | uint16 | uint32 | uint64 | uintptr | float32 | float64
+}
--- a/maputil/map.go
+++ b/maputil/map.go
@@ -0,0 +1,107 @@
+// Copyright 2021 dudaodong@gmail.com. All rights reserved.
+// Use of this source code is governed by MIT license
+
+// Package maputil includes some functions to manipulate map.
+package maputil
+
+import "reflect"
+
+// Keys returns a slice of the map's keys
+func Keys[K comparable, V any](m map[K]V) []K {
+	keys := make([]K, 0, len(m))
+
+	for k := range m {
+		keys = append(keys, k)
+	}
+
+	return keys
+}
+
+// Values returns a slice of the map's values
+func Values[K comparable, V any](m map[K]V) []V {
+	values := make([]V, 0, len(m))
+
+	for _, v := range m {
+		values = append(values, v)
+	}
+
+	return values
+}
+
+// Merge maps, next key will overwrite previous key
+func Merge[K comparable, V any](maps ...map[K]V) map[K]V {
+	res := make(map[K]V, 0)
+
+	for _, m := range maps {
+		for k, v := range m {
+			res[k] = v
+		}
+	}
+
+	return res
+}
+
+// ForEach executes iteratee funcation for every key and value pair in map
+func ForEach[K comparable, V any](m map[K]V, iteratee func(key K, value V)) {
+	for k, v := range m {
+		iteratee(k, v)
+	}
+}
+
+// Filter iterates over map, return a new map contains all key and value pairs pass the predicate function
+func Filter[K comparable, V any](m map[K]V, predicate func(key K, value V) bool) map[K]V {
+	res := make(map[K]V)
+
+	for k, v := range m {
+		if predicate(k, v) {
+			res[k] = v
+		}
+	}
+	return res
+}
+
+// Intersect iterates over maps, return a new map of key and value pairs in all given maps
+func Intersect[K comparable, V any](maps ...map[K]V) map[K]V {
+	if len(maps) == 0 {
+		return map[K]V{}
+	}
+	if len(maps) == 1 {
+		return maps[0]
+	}
+
+	res := make(map[K]V)
+
+	reducer := func(m1, m2 map[K]V) map[K]V {
+		m := make(map[K]V)
+		for k, v1 := range m1 {
+			if v2, ok := m2[k]; ok && reflect.DeepEqual(v1, v2) {
+				m[k] = v1
+			}
+		}
+		return m
+	}
+
+	reduceMaps := make([]map[K]V, 2, 2)
+	res = reducer(maps[0], maps[1])
+
+	for i := 2; i < len(maps); i++ {
+		reduceMaps[0] = res
+		reduceMaps[1] = maps[i]
+		res = reducer(reduceMaps[0], reduceMaps[1])
+	}
+
+	return res
+}
+
+
+// Minus creates an map of whose key in mapA but not in mapB
+func Minus[K comparable, V any](mapA, mapB map[K]V) map[K]V {
+	res := make(map[K]V)
+
+	for k, v := range mapA {
+		if _, ok := mapB[k]; !ok {
+			res[k] = v
+		}
+	}
+	return res
+}
--- a/maputil/map_test.go
+++ b/maputil/map_test.go
@@ -0,0 +1,150 @@
+package maputil
+
+import (
+	"sort"
+	"testing"
+
+	"github.com/duke-git/lancet/v2/internal"
+)
+
+func TestKeys(t *testing.T) {
+	assert := internal.NewAssert(t, "TestKeys")
+
+	m := map[int]string{
+		1: "a",
+		2: "a",
+		3: "b",
+		4: "c",
+		5: "d",
+	}
+
+	keys := Keys(m)
+	sort.Ints(keys)
+
+	assert.Equal([]int{1, 2, 3, 4, 5}, keys)
+}
+
+func TestValues(t *testing.T) {
+	assert := internal.NewAssert(t, "TestValues")
+
+	m := map[int]string{
+		1: "a",
+		2: "a",
+		3: "b",
+		4: "c",
+		5: "d",
+	}
+
+	values := Values(m)
+	sort.Strings(values)
+
+	assert.Equal([]string{"a", "a", "b", "c", "d"}, values)
+}
+
+func TestMerge(t *testing.T) {
+	assert := internal.NewAssert(t, "TestMerge")
+
+	m1 := map[int]string{
+		1: "a",
+		2: "b",
+	}
+	m2 := map[int]string{
+		1: "1",
+		3: "2",
+	}
+
+	expected := map[int]string{
+		1: "1",
+		2: "b",
+		3: "2",
+	}
+	acturl := Merge(m1, m2)
+
+	assert.Equal(expected, acturl)
+}
+
+func TestForEach(t *testing.T) {
+	assert := internal.NewAssert(t, "TestForEach")
+
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+		"d": 4,
+	}
+
+	var sum int
+
+	ForEach(m, func(_ string, value int) {
+		sum += value
+	})
+
+	assert.Equal(10, sum)
+}
+
+func TestFilter(t *testing.T) {
+	assert := internal.NewAssert(t, "TestFilter")
+
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+		"d": 4,
+		"e": 5,
+	}
+	isEven := func(_ string, value int) bool {
+		return value%2 == 0
+	}
+
+	acturl := Filter(m, isEven)
+
+	assert.Equal(map[string]int{
+		"b": 2,
+		"d": 4,
+	}, acturl)
+}
+
+func TestIntersect(t *testing.T) {
+	assert := internal.NewAssert(t, "TestIntersect")
+
+	m1 := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+	}
+
+	m2 := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 6,
+		"d": 7,
+	}
+
+	m3 := map[string]int{
+		"a": 1,
+		"b": 9,
+		"e": 9,
+	}
+
+	assert.Equal(map[string]int{"a": 1, "b": 2, "c": 3}, Intersect(m1))
+	assert.Equal(map[string]int{"a": 1, "b": 2}, Intersect(m1, m2))
+	assert.Equal(map[string]int{"a": 1}, Intersect(m1, m2, m3))
+}
+
+func TestMinus(t *testing.T) {
+	assert := internal.NewAssert(t, "TestMinus")
+
+	m1 := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+	}
+
+	m2 := map[string]int{
+		"a": 11,
+		"b": 22,
+		"d": 33,
+	}
+
+	assert.Equal(map[string]int{"c": 3}, Minus(m1, m2))
+}
--- a/mathutil/mathutil.go
+++ b/mathutil/mathutil.go
@@ -9,6 +9,8 @@ import (
 	"math"
 	"strconv"
 	"strings"
+
+	"github.com/duke-git/lancet/v2/lancetconstraints"
 )

 // Exponent calculate x^n
@@ -90,3 +92,40 @@ func TruncRound(x float64, n int) float64 {
 	res, _ := strconv.ParseFloat(newFloat, 64)
 	return res
 }
+
+// Max return max value of params
+func Max[T lancetconstraints.Number](numbers ...T) T {
+	max := numbers[0]
+
+	for _, v := range numbers {
+		if max < v {
+			max = v
+		}
+	}
+
+	return max
+}
+
+// Min return min value of params
+func Min[T lancetconstraints.Number](numbers ...T) T {
+	min := numbers[0]
+
+	for _, v := range numbers {
+		if min > v {
+			min = v
+		}
+	}
+
+	return min
+}
+
+// Average return average value of params
+func Average[T lancetconstraints.Number](numbers ...T) T {
+	var sum T
+	n := T(len(numbers))
+
+	for _, v := range numbers {
+		sum += v
+	}
+	return sum / n
+}
--- a/mathutil/mathutil_test.go
+++ b/mathutil/mathutil_test.go
@@ -70,3 +70,29 @@ func TestTruncRound(t *testing.T) {
 	assert.Equal(TruncRound(0.125, 3), float64(0.125))
 	assert.Equal(TruncRound(33.33333, 2), float64(33.33))
 }
+
+func TestAverage(t *testing.T) {
+	assert := internal.NewAssert(t, "TestAverage")
+
+	assert.Equal(Average(0, 0), 0)
+	assert.Equal(Average(1, 1), 1)
+	avg := Average(1.2, 1.4)
+	t.Log(avg)
+	assert.Equal(1.3, RoundToFloat(avg, 1))
+}
+
+func TestMax(t *testing.T) {
+	assert := internal.NewAssert(t, "TestMax")
+
+	assert.Equal(Max(0, 0), 0)
+	assert.Equal(Max(1, 2, 3), 3)
+	assert.Equal(Max(1.2, 1.4, 1.1, 1.4), 1.4)
+}
+
+func TestMin(t *testing.T) {
+	assert := internal.NewAssert(t, "TestMin")
+
+	assert.Equal(Min(0, 0), 0)
+	assert.Equal(Min(1, 2, 3), 1)
+	assert.Equal(Min(1.2, 1.4, 1.1, 1.4), 1.1)
+}
--- a/slice/slice.go
+++ b/slice/slice.go
@@ -253,6 +253,25 @@ func GroupBy[T any](slice []T, groupFn func(index int, t T) bool) ([]T, []T) {
 	return groupA, groupB
 }

+// GroupWith return a map composed of keys generated from the results of running each element of slice thru iteratee.
+func GroupWith[T any, U comparable](slice []T, iteratee func(T) U) map[U][]T {
+	if iteratee == nil {
+		panic("iteratee func is missing")
+	}
+
+	res := make(map[U][]T)
+
+	for _, v := range slice {
+		key := iteratee(v)
+		if _, ok := res[key]; !ok {
+			res[key] = []T{}
+		}
+		res[key] = append(res[key], v)
+	}
+
+	return res
+}
+
 // Find iterates over elements of slice, returning the first one that passes a truth test on predicate function.
 // If return T is nil then no items matched the predicate func
 func Find[T any](slice []T, predicate func(index int, t T) bool) (*T, bool) {
@@ -552,7 +571,6 @@ func Union[T any](slices ...[]T) []T {

 // Intersection creates a slice of unique values that included by all slices.
 func Intersection[T any](slices ...[]T) []T {
-	var res []T
 	if len(slices) == 0 {
 		return []T{}
 	}
@@ -560,28 +578,51 @@ func Intersection[T any](slices ...[]T) []T {
 		return Unique(slices[0])
 	}

-	//return elements both in slice1 and slice2
-	reduceFunc := func(slice1, slice2 []T) []T {
+	var res []T
+
+	reducer := func(s1, s2 []T) []T {
 		s := make([]T, 0, 0)
-		for _, v := range slice1 {
-			if Contain(slice2, v) {
+		for _, v := range s1 {
+			if Contain(s2, v) {
 				s = append(s, v)
 			}
 		}
 		return s
 	}

-	res = reduceFunc(slices[0], slices[1])
+	res = reducer(slices[0], slices[1])

-	if len(slices) == 2 {
-		return Unique(res)
+	reduceSlice := make([][]T, 2, 2)
+	for i := 2; i < len(slices); i++ {
+		reduceSlice[0] = res
+		reduceSlice[1] = slices[i]
+		res = reducer(reduceSlice[0], reduceSlice[1])
 	}

-	tmp := make([][]T, 2, 2)
-	for i := 2; i < len(slices); i++ {
-		tmp[0] = res
-		tmp[1] = slices[i]
-		res = reduceFunc(tmp[0], tmp[1])
+	return Unique(res)
+}
+
+// SymmetricDifference oppoiste operation of intersection function
+func SymmetricDifference[T any](slices ...[]T) []T {
+	if len(slices) == 0 {
+		return []T{}
+	}
+	if len(slices) == 1 {
+		return Unique(slices[0])
+	}
+
+	res := make([]T, 0)
+
+	intersectSlice := Intersection(slices...)
+
+	for i := 0; i < len(slices); i++ {
+		slice := slices[i]
+		for _, v := range slice {
+			if !Contain(intersectSlice, v) {
+				res = append(res, v)
+			}
+		}
+
 	}

 	return Unique(res)
--- a/slice/slice_test.go
+++ b/slice/slice_test.go
@@ -1,6 +1,7 @@
 package slice

 import (
+	"math"
 	"testing"

 	"github.com/duke-git/lancet/v2/internal"
@@ -142,6 +143,20 @@ func TestGroupBy(t *testing.T) {
 	assert.Equal(expectedOdd, odd)
 }

+func TestGroupWith(t *testing.T) {
+	nums := []float64{6.1, 4.2, 6.3}
+	floor := func(num float64) float64 {
+		return math.Floor(num)
+	}
+	expected := map[float64][]float64{
+		4: {4.2},
+		6: {6.1, 6.3},
+	}
+	actual := GroupWith(nums, floor)
+	assert := internal.NewAssert(t, "TestGroupWith")
+	assert.Equal(expected, actual)
+}
+
 func TestCount(t *testing.T) {
 	nums := []int{1, 2, 3, 4, 5, 6}
 	evenFunc := func(i, num int) bool {
@@ -392,7 +407,18 @@ func TestIntersection(t *testing.T) {
 	for i := 0; i < len(res); i++ {
 		assert.Equal(expected[i], res[i])
 	}
-	// assert.IsNil(Intersection())
+}
+
+func TestSymmetricDifference(t *testing.T) {
+	assert := internal.NewAssert(t, "TestSymmetricDifference")
+
+	s1 := []int{1, 2, 3}
+	s2 := []int{1, 2, 4}
+	s3 := []int{1, 2, 3, 5}
+
+	assert.Equal([]int{1, 2, 3}, SymmetricDifference(s1))
+	assert.Equal([]int{3, 4}, SymmetricDifference(s1, s2))
+	assert.Equal([]int{3, 4, 5}, SymmetricDifference(s1, s2, s3))
 }

 func TestReverse(t *testing.T) {
Author	SHA1	Message	Date
dudaodong	1ec3a5af87	release v2.0.3	2022-04-06 10:54:54 +08:00
dudaodong	f31dde97b1	docs: add maputil docs in read me file	2022-04-05 14:24:33 +08:00
dudaodong	1718fd1cf1	docs: add doc for maputil package	2022-04-05 14:16:58 +08:00
dudaodong	513c0f829c	docs: add doc for SymmetricDifference fun in slice doc	2022-04-05 13:47:13 +08:00
dudaodong	c51a806aff	feat: add SymmetricDifference func for set	2022-04-01 18:06:34 +08:00
dudaodong	3c16d50c4b	refactor: rename ReverseIntersect to SymmetricDifference	2022-04-01 18:05:02 +08:00
dudaodong	21dd6ab8aa	feat: add SymmetricDifference func for set	2022-04-01 18:02:12 +08:00
dudaodong	f5bf5183cc	feat: add Minus func for set	2022-04-01 16:48:37 +08:00
dudaodong	f28b5b2f92	feat: add Minus func for set	2022-04-01 16:44:25 +08:00
dudaodong	79867e8a63	feat: add ReverseIntersect function	2022-03-31 19:42:27 +08:00
dudaodong	19939c2b03	feat: add Minus func	2022-03-31 18:00:11 +08:00
dudaodong	bf7ffbfa8d	feat: add Intersect func	2022-03-31 16:56:12 +08:00
dudaodong	cbb46f9cb4	feat: add Filter func	2022-03-30 19:52:43 +08:00
dudaodong	3ad142d5d7	feat: add ForEach func	2022-03-30 19:41:55 +08:00
dudaodong	1a436aeb41	feat: add Merge func	2022-03-30 18:06:22 +08:00
dudaodong	1af8fe8daf	test: add unit test for Keys and Values func	2022-03-30 17:45:17 +08:00
dudaodong	ae54c8db6f	feat: add Values func	2022-03-30 17:34:01 +08:00
dudaodong	be942ec33e	feat: add package maputil and Keys func	2022-03-30 17:27:50 +08:00
dudaodong	fafb59dad6	update readme file	2022-03-29 11:02:27 +08:00
dudaodong	e36c01cac9	release v2.0.2	2022-03-29 11:01:31 +08:00
dudaodong	aa0afa8d94	release v1.2.7	2022-03-29 11:01:06 +08:00
dudaodong	18e0031e0e	fix: fix TestInsertionSort	2022-03-26 21:06:05 +08:00
dudaodong	a5018c110c	fix: fix bug in ToBytes func	2022-03-26 20:54:37 +08:00
dudaodong	142deb83b2	fix: fix InsertionSort bug	2022-03-26 18:25:42 +08:00
dudaodong	ccc0188352	feat: add DeleteValue for SinglyLink	2022-03-24 17:56:45 +08:00
dudaodong	98dba83107	release v2.0.1	2022-03-22 14:47:23 +08:00
dudaodong	9c6aff9030	fix: fix lint warning 'ineffassign'	2022-03-22 14:45:16 +08:00
dudaodong	7fd9a94922	fix: fix lint warning 'ineffassign'	2022-03-22 14:36:35 +08:00
dudaodong	dd3b1f3aed	docs: add doc for some new funcs	2022-03-22 14:10:58 +08:00
dudaodong	f9dce592e8	docs: add doc for Min, Max, and Average	2022-03-22 10:43:00 +08:00
dudaodong	c4b0967623	feat: add Max, Min, and Average function	2022-03-22 10:26:43 +08:00
dudaodong	41613061d5	docs: add GroupWith doc	2022-03-21 20:10:39 +08:00
dudaodong	50ef63e27d	feat: add GroupWith func	2022-03-21 15:29:10 +08:00
dudaodong	3ae4a35d04	fix: format timezone issue	2022-03-19 19:24:28 +08:00
dudaodong	89ea0ee15a	fix: format timezone issue	2022-03-19 19:08:34 +08:00
dudaodong	85399e23ed	fix: format timezone issue	2022-03-19 18:42:22 +08:00
dudaodong	19a6f218e6	fix: format time in local timezone	2022-03-19 18:23:06 +08:00
dudaodong	ccaf290b63	docs: add doc for datetime/conversion.go	2022-03-18 18:18:28 +08:00
dudaodong	54745d512c	test: add unit test and func comment for time conversion	2022-03-18 17:48:57 +08:00
dudaodong	39234d4722	Merge branch 'main' of github.com:duke-git/lancet into main	2022-03-17 19:46:31 +08:00
dudaodong	4b4310265b	fix: update TestListFileNames	2022-03-17 19:46:19 +08:00
wangxudong123	d8a982bf07	增加时间转换 (#25 ) Co-authored-by: wangxd01 <wangxd01@mingyuanyun.com>	2022-03-17 19:44:24 +08:00
dudaodong	0334a6f02b	docs: fix some issues	2022-03-17 11:55:52 +08:00
dudaodong	ae0c613b8e	add package comment	2022-03-17 11:55:08 +08:00