release v2.1.16

doc: add new function docs
feat: add ContainBy function
2026-02-09 15:12:26 +08:00 · 2023-03-01 10:08:53 +08:00 · 2023-02-28 15:03:02 +08:00 · 2023-02-24 14:19:10 +08:00 · 2023-02-24 11:23:02 +08:00 · 2023-02-24 11:14:59 +08:00
28 changed files with 3073 additions and 137 deletions
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@
 <br/>

 ![Go version](https://img.shields.io/badge/go-%3E%3Dv1.18-9cf)
-[![Release](https://img.shields.io/badge/release-2.1.15-green.svg)](https://github.com/duke-git/lancet/releases)
+[![Release](https://img.shields.io/badge/release-2.1.16-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)
@@ -38,10 +38,10 @@ 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. The latest of v1.x.x is v1.3.6. </b>
+2. <b>For users who use version below go1.18, you should install v1.x.x. The latest of v1.x.x is v1.3.7. </b>

 ```go
-go get github.com/duke-git/lancet@v1.3.6 // below go1.18, install latest version of v1.x.x
+go get github.com/duke-git/lancet@v1.3.7 // below go1.18, install latest version of v1.x.x
 ```

 ## Usage
@@ -248,6 +248,10 @@ import "github.com/duke-git/lancet/v2/convertor"
    [[play](https://go.dev/play/p/zI6xsmuQRbn)]
 -   **<big>DeepClone</big>** : creates a deep copy of passed item, can't clone unexported field of struct.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/convertor.md#DeepClone)]
+    [[play](https://go.dev/play/p/j4DP5dquxnk)]
+-   **<big>CopyProperties</big>** : copies each field from the source struct into the destination struct.
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/convertor.md#CopyProperties)]
+

 ### 5. Cryptor package is for data encryption and decryption.

@@ -604,12 +608,24 @@ import "github.com/duke-git/lancet/v2/maputil"
 -   **<big>Filter</big>** : iterates over map, return a new map contains all key and value pairs pass the predicate function.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#Filter)]
    [[play](https://go.dev/play/p/fSvF3wxuNG7)]
+-   **<big>FilterByKeys</big>** : iterates over map, return a new map whose keys are all given keys
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#FilterByKeys)]
+-   **<big>FilterByValues</big>** : iterates over map, return a new map whose values are all given values.
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#FilterByValues)]
+-   **<big>OmitBy</big>** : the opposite of Filter, removes all the map elements for which the predicate function returns true.
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#OmitBy)]
+-   **<big>OmitByKeys</big>** : the opposite of FilterByKeys, extracts all the map elements which keys are not omitted.
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#OmitByKeys)]
+-   **<big>OmitByValues</big>** : the opposite of FilterByValues. remov all elements whose value are in the give slice.
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#OmitByValues)]
 -   **<big>Intersect</big>** : iterates over maps, return a new map of key and value pairs in all given maps.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#Intersect)]
    [[play](https://go.dev/play/p/Zld0oj3sjcC)]
 -   **<big>Keys</big>** : returns a slice of the map's keys.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#Keys)]
    [[play](https://go.dev/play/p/xNB5bTb97Wd)]
+-   **<big>KeysBy</big>** : creates a slice whose element is the result of function mapper invoked by every map's key.
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#KeysBy)]
 -   **<big>Merge</big>** : merge maps, next key will overwrite previous key.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#Merge)]
    [[play](https://go.dev/play/p/H95LENF1uB-)]
@@ -619,6 +635,18 @@ import "github.com/duke-git/lancet/v2/maputil"
 -   **<big>Values</big>** : returns a slice of the map's values.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#Values)]
    [[play](https://go.dev/play/p/CBKdUc5FTW6)]
+-   **<big>ValuesBy</big>** : creates a slice whose element is the result of function mapper invoked by every map's value.
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#ValuesBy)]
+-   **<big>MapKeys</big>** : transforms a map to other type map by manipulating it's keys.
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#MapKeys)]
+-   **<big>MapValues</big>** : transforms a map to other type map by manipulating it's values.
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#MapValues)]
+-   **<big>Entries</big>** : transforms a map into array of key/value pairs.
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#Entries)]
+-   **<big>FromEntries</big>** : creates a map based on a slice of key/value pairs.
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#FromEntries)]
+-   **<big>Transform</big>** : transform a map to another type map.
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#Transform)]
 -   **<big>IsDisjoint</big>** : check two map are disjoint if they have no keys in common.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil.md#IsDisjoint)]
    [[play](https://go.dev/play/p/N9qgYg_Ho6f)]
@@ -804,6 +832,8 @@ import "github.com/duke-git/lancet/v2/slice"
 -   **<big>Contain</big>** : check if the value is in the slice or not.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#Contain)]
    [[play](https://go.dev/play/p/_454yEHcNjf)]
+-   **<big>ContainBy</big>** : returns true if predicate function return true.
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#ContainBy)]
 -   **<big>ContainSubSlice</big>** : check if the slice contain a given subslice or not.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#ContainSubSlice)]
    [[play](https://go.dev/play/p/bcuQ3UT6Sev)]
@@ -836,13 +866,16 @@ import "github.com/duke-git/lancet/v2/slice"
    [[play](https://go.dev/play/p/pJ-d6MUWcvK)]
 -   **<big>Drop</big>** : drop n elements from the start of a slice.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#Drop)]
-    [[play](https://go.dev/play/p/pJ-d6MUWcvK)]
+    [[play](https://go.dev/play/p/jnPO2yQsT8H)]
 -   **<big>DropRight</big>** : drop n elements from the end of a slice.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#DropRight)]
+    [[play](https://go.dev/play/p/8bcXvywZezG)]
 -   **<big>DropWhile</big>** : drop n elements from the start of a slice while predicate function returns true.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#DropWhile)]
+    [[play](https://go.dev/play/p/4rt252UV_qs)]
 -   **<big>DropRightWhile</big>** : drop n elements from the end of a slice while predicate function returns true.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#DropRightWhile)]
+    [[play](https://go.dev/play/p/6wyK3zMY56e)]
 -   **<big>Equal</big>** : checks if two slices are equal: the same length and all elements' order and value are equal.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#Equal)]
    [[play](https://go.dev/play/p/WcRQJ37ifPa)]
@@ -855,6 +888,8 @@ import "github.com/duke-git/lancet/v2/slice"
 -   **<big>Filter</big>** : iterates over elements of slice, returning an slice of all elements pass the predicate function.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#Filter)]
    [[play](https://go.dev/play/p/SdPna-7qK4T)]
+-   **<big>FilterMap</big>** : returns a slice which apply both filtering and mapping to the given slice.
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#FilterMap)]
 -   **<big>Find</big>** : iterates over elements of slice, returning the first one that passes a truth test on predicate function.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#Find)]
    [[play](https://go.dev/play/p/CBKeBoHVLgq)]
@@ -867,6 +902,8 @@ import "github.com/duke-git/lancet/v2/slice"
 -   **<big>FlattenDeep</big>** : flattens slice recursive to one level.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#FlattenDeep)]
    [[play](https://go.dev/play/p/yjYNHPyCFaF)]
+-   **<big>FlatMap</big>** : manipulates a slice and transforms and flattens it to a slice of another type.
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#FlatMap)]
 -   **<big>ForEach</big>** : iterates over elements of slice and invokes function for each element.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#ForEach)]
    [[play](https://go.dev/play/p/DrPaa4YsHRF)]
@@ -920,12 +957,16 @@ import "github.com/duke-git/lancet/v2/slice"
    [[play](https://go.dev/play/p/YHvhnWGU3Ge)]
 -   **<big>IsAscending</big>** : Checks if a slice is ascending order.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#IsAscending)]
+    [[play](https://go.dev/play/p/9CtsFjet4SH)]
 -   **<big>IsDescending</big>** : Checks if a slice is descending order.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#IsDescending)]
+    [[play](https://go.dev/play/p/U_LljFXma14)]
 -   **<big>IsSorted</big>** : Checks if a slice is sorted (ascending or descending).
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#IsSorted)]
+    [[play](https://go.dev/play/p/nCE8wPLwSA-)]
 -   **<big>IsSortedByKey</big>** : Checks if a slice is sorted by iteratee function.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#IsSortedByKey)]
+    [[play](https://go.dev/play/p/tUoGB7DOHI4)]
 -   **<big>Sort</big>** : sorts a slice of any ordered type(number or string).
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice.md#Sort)]
    [[play](https://go.dev/play/p/V9AVjzf_4Fk)]
@@ -1012,6 +1053,8 @@ import "github.com/duke-git/lancet/v2/strutil"
 -   **<big>UpperFirst</big>** : converts the first character of string to upper case.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/strutil.md#UpperFirst)]
    [[play](https://go.dev/play/p/sBbBxRbs8MM)]
+-   **<big>Pad</big>** : pads string on the left and right side if it's shorter than size.
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/strutil.md#Pad)]
 -   **<big>PadEnd</big>** : pads string with given characters on the right side if it's shorter than limit size. Padding characters are truncated if they exceed size.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/strutil.md#PadEnd)]
    [[play](https://go.dev/play/p/9xP8rN0vz--)]
@@ -1039,6 +1082,10 @@ import "github.com/duke-git/lancet/v2/strutil"
 -   **<big>Unwrap</big>** : unwrap a given string from anther string. will change source string.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/strutil.md#Unwrap)]
    [[play](https://go.dev/play/p/Ec2q4BzCpG-)]
+-   **<big>SplitWords</big>** : splits a string into words, word only contains alphabetic characters.
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/strutil.md#SplitWords)]
+-   **<big>WordCount</big>** : return the number of meaningful word of a string, word only contains alphabetic characters.
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/strutil.md#WordCount)]

 ### 19. System package contain some functions about os, runtime, shell command.

@@ -1178,31 +1225,43 @@ import "github.com/duke-git/lancet/v2/xerror"
 #### Function list:
 -   **<big>New</big>** : creates a new XError pointer instance with message.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror.md#New)]
+    [[play](https://go.dev/play/p/w4oWZts7q7f)]
 -   **<big>Wrap</big>** : creates a new XError pointer instance based on error object, and add message.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror.md#Wrap)]
+    [[play](https://go.dev/play/p/5385qT2dCi4)]
 -   **<big>Unwrap</big>** : returns unwrapped XError from err by errors.As. If no XError, returns nil.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror.md#Unwrap)]
+    [[play](https://go.dev/play/p/LKMLep723tu)]
 -   **<big>XError_Wrap</big>** : creates a new XError and copy message and id to new one.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror.md#XError_Wrap)]
+    [[play](https://go.dev/play/p/5385qT2dCi4)]
 -   **<big>XError_Unwrap</big>** : Compatible with github.com/pkg/errors.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror.md#XError_Unwrap)]
+    [[play](https://go.dev/play/p/VUXJ8BST4c6)]
 -   **<big>XError_With</big>** : adds key and value related to the XError object.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror.md#XError_With)]
+    [[play](https://go.dev/play/p/ow8UISXX_Dp)]
 -   **<big>XError_Id</big>** : sets XError object id to check equality in XError.Is.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror.md#XError_Id)]
+    [[play](https://go.dev/play/p/X6HBlsy58U9)]
 -   **<big>XError_Is</big>** : checks if target error is XError and Error.id of two errors are matched.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror.md#XError_Is)]
+    [[play](https://go.dev/play/p/X6HBlsy58U9)]
 -   **<big>XError_Values</big>** : returns map of key and value that is set by XError.With function. 
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror.md#XError_Values)]
+    [[play](https://go.dev/play/p/ow8UISXX_Dp)]
 -   **<big>XError_StackTrace</big>** : returns stack trace which is compatible with pkg/errors.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror.md#XError_StackTrace)]
+    [[play](https://go.dev/play/p/6FAvSQpa7pc)]
 -   **<big>XError_Info</big>** : returns information of xerror, which can be printed.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror.md#XError_Info)]
+    [[play](https://go.dev/play/p/1ZX0ME1F-Jb)]
 -   **<big>XError_Error</big>** : implements standard error interface.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror.md#XError_Error)]
+    [[play](https://go.dev/play/p/w4oWZts7q7f)]
 -   **<big>TryUnwrap</big>** : check if err is nil then it returns a valid value. If err is not nil, TryUnwrap panics with err.
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror.md#TryUnwrap)]
-    [[play](https://go.dev/play/p/w84d7Mb3Afk)]
+    [[play](https://go.dev/play/p/acyZVkNZEeW)]


 ## How to Contribute
--- a/README_zh-CN.md
+++ b/README_zh-CN.md
@@ -4,7 +4,7 @@
 <br/>

 ![Go version](https://img.shields.io/badge/go-%3E%3Dv1.18-9cf)
-[![Release](https://img.shields.io/badge/release-2.1.15-green.svg)](https://github.com/duke-git/lancet/releases)
+[![Release](https://img.shields.io/badge/release-2.1.16-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)
@@ -37,10 +37,10 @@
 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 v1.3.6。</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 v1.3.7。</b>

 ```go
-go get github.com/duke-git/lancet@v1.3.6 // 使用go1.18以下版本, 必须安装v1.x.x版本
+go get github.com/duke-git/lancet@v1.3.7 // 使用go1.18以下版本, 必须安装v1.x.x版本
 ```

 ## 用法
@@ -247,6 +247,9 @@ import "github.com/duke-git/lancet/v2/convertor"
    [[play](https://go.dev/play/p/zI6xsmuQRbn)]
 -   **<big>DeepClone</big>** : 创建一个传入值的深拷贝, 无法克隆结构体的非导出字段。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/convertor_zh-CN.md#DeepClone)]
+    [[play](https://go.dev/play/p/j4DP5dquxnk)]
+-   **<big>CopyProperties</big>** : 拷贝不同结构体之间的同名字段。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/convertor_zh-CN.md#CopyProperties)]


 ### 5. cryptor 加密包支持数据加密和解密，获取 md5，hash 值。支持 base64, md5, hmac, aes, des, rsa。
@@ -608,12 +611,24 @@ import "github.com/duke-git/lancet/v2/maputil"
 -   **<big>Filter</big>** : 迭代 map 中的每对 key 和 value，返回 map，其中的 key 和 value 符合 predicate 函数。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN.md#Filter)]
    [[play](https://go.dev/play/p/fSvF3wxuNG7)]
+-   **<big>FilterByKeys</big>** : 迭代map, 返回一个新map，其key都是给定的key值。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN#FilterByKeys)]
+-   **<big>FilterByValues</big>** : 迭代map, 返回一个新map，其value都是给定的value值。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN#FilterByValues)]
+-   **<big>OmitBy</big>** : Filter的反向操作, 迭代map中的每对key和value, 删除符合predicate函数的key, value, 返回新map。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN#OmitBy)]
+-   **<big>OmitByKeys</big>** : FilterByKeys的反向操作, 迭代map, 返回一个新map，其key不包括给定的key值。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN#OmitByKeys)]
+-   **<big>OmitByValues</big>** : FilterByValues的反向操作, 迭代map, 返回一个新map，其value不包括给定的value值。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN#OmitByValues)]
 -   **<big>Intersect</big>** : 多个 map 的交集操作。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN.md#Intersect)]
    [[play](https://go.dev/play/p/Zld0oj3sjcC)]
 -   **<big>Keys</big>** : 返回 map 中所有 key 组成的切片。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN.md#Keys)]
    [[play](https://go.dev/play/p/xNB5bTb97Wd)]
+-   **<big>KeysBy</big>** : 创建一个切片，其元素是每个map的key调用mapper函数的结果。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN#KeysBy)]
 -   **<big>Merge</big>** : 合并多个 map, 相同的 key 会被之后的 key 覆盖。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN.md#Merge)]
    [[play](https://go.dev/play/p/H95LENF1uB-)]
@@ -623,7 +638,19 @@ import "github.com/duke-git/lancet/v2/maputil"
 -   **<big>Values</big>** : 返回 map 中所有 values 组成的切片
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN.md#Values)]
    [[play](https://go.dev/play/p/CBKdUc5FTW6)]
-   **<big>IsDisjoint</big>** : 验证两个 map 是否具有不同的 key。
+-   **<big>ValuesBy</big>** : 创建一个切片，其元素是每个map的value调用mapper函数的结果。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN#ValuesBy)]
+-   **<big>MapKeys</big>** : 操作map的每个key，然后转为新的map。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN#MapKeys)]
+-   **<big>MapValues</big>** : 操作map的每个value，然后转为新的map。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN#MapValues)]
+-   **<big>Entries</big>** : 将map转换为键/值对切片。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN#Entries)]
+-   **<big>FromEntries</big>** : 基于键/值对的切片创建map。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN#FromEntries)]
+-   **<big>Transform</big>** : 将map转换为其他类型的map。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN#Transform)]
+-   **<big>IsDisjoint</big>** : 验证两个map是否具有不同的key。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/maputil_zh-CN.md#IsDisjoint)]
    [[play](https://go.dev/play/p/N9qgYg_Ho6f)]

@@ -812,6 +839,8 @@ import "github.com/duke-git/lancet/v2/slice"
 -   **<big>Contain</big>** : 判断slice是否包含value。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#Contain)]
    [[play](https://go.dev/play/p/_454yEHcNjf)]
+-   **<big>ContainBy</big>** : 根据predicate函数判断切片是否包含某个值。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#ContainBy)]
 -   **<big>ContainSubSlice</big>** : 判断slice是否包含subslice。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#ContainSubSlice)]
    [[play](https://go.dev/play/p/bcuQ3UT6Sev)]
@@ -844,13 +873,16 @@ import "github.com/duke-git/lancet/v2/slice"
    [[play](https://go.dev/play/p/pJ-d6MUWcvK)]
 -   **<big>Drop</big>** : 从切片头部删除n个元素。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#Drop)]
-    [[play](https://go.dev/play/p/pJ-d6MUWcvK)]
+    [[play](https://go.dev/play/p/jnPO2yQsT8H)]
 -   **<big>DropRight</big>** : 从切片尾部删除n个元素。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#DropRight)]
+    [[play](https://go.dev/play/p/8bcXvywZezG)]
 -   **<big>DropWhile</big>** : 从切片的头部删除n个元素，这个n个元素满足predicate函数返回true。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#DropWhile)]
+    [[play](https://go.dev/play/p/4rt252UV_qs)]
 -   **<big>DropRightWhile</big>** : 从切片的尾部删除n个元素，这个n个元素满足predicate函数返回true。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#DropRightWhile)]
+    [[play](https://go.dev/play/p/6wyK3zMY56e)]
 -   **<big>Equal</big>** : 检查两个切片是否相等，相等条件：切片长度相同，元素顺序和值都相同。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#Equal)]
    [[play](https://go.dev/play/p/WcRQJ37ifPa)]
@@ -863,6 +895,8 @@ import "github.com/duke-git/lancet/v2/slice"
 -   **<big>Filter</big>** : 返回切片中通过predicate函数真值测试的所有元素。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#Filter)]
    [[play](https://go.dev/play/p/SdPna-7qK4T)]
+-   **<big>FilterMap</big>** : 返回一个将filter和map操作应用于给定切片的切片。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#FilterMap)]
 -   **<big>Find</big>** : 遍历切片的元素，返回第一个通过predicate函数真值测试的元素。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#Find)]
    [[play](https://go.dev/play/p/CBKeBoHVLgq)]
@@ -875,6 +909,8 @@ import "github.com/duke-git/lancet/v2/slice"
 -   **<big>FlattenDeep</big>** : 将多维切片递归展平到一层。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#FlattenDeep)]
    [[play](https://go.dev/play/p/yjYNHPyCFaF)]
+-   **<big>FlatMap</big>** : 将切片转换为其它类型切片。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#FlatMap)]
 -   **<big>ForEach</big>** : 遍历切片的元素并为每个元素调用iteratee函数。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#ForEach)]
    [[play](https://go.dev/play/p/DrPaa4YsHRF)]
@@ -928,12 +964,16 @@ import "github.com/duke-git/lancet/v2/slice"
    [[play](https://go.dev/play/p/YHvhnWGU3Ge)]
 -   **<big>IsAscending</big>** : 检查切片元素是否按升序排列。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#IsAscending)]
+    [[play](https://go.dev/play/p/9CtsFjet4SH)]
 -   **<big>IsDescending</big>** : 检查切片元素是否按降序排列。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#IsDescending)]
+    [[play](https://go.dev/play/p/U_LljFXma14)]
 -   **<big>IsSorted</big>** : 检查切片元素是否是有序的（升序或降序）。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#IsSorted)]
+    [[play](https://go.dev/play/p/nCE8wPLwSA-)]
 -   **<big>IsSortedByKey</big>** : 通过iteratee函数，检查切片元素是否是有序的。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#IsSortedByKey)]
+    [[play](https://go.dev/play/p/tUoGB7DOHI4)]
 -   **<big>Sort</big>** : 对任何有序类型（数字或字符串）的切片进行排序，使用快速排序算法。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/slice_zh-CN.md#Sort)]
    [[play](https://go.dev/play/p/V9AVjzf_4Fk)]
@@ -1022,6 +1062,8 @@ import "github.com/duke-git/lancet/v2/strutil"
 -   **<big>UpperFirst</big>** : 将字符串的第一个字符转换为大写形式。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/strutil_zh-CN.md#UpperFirst)]
    [[play](https://go.dev/play/p/sBbBxRbs8MM)]
+-   **<big>Pad</big>** : 如果字符串长度短于size，则在左右两侧填充字符串。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/strutil_zh-CN.md#Pad)]
 -   **<big>PadEnd</big>** : 如果字符串短于限制大小，则在右侧用给定字符填充字符串。 如果填充字符超出大小，它们将被截断。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/strutil_zh-CN.md#PadEnd)]
    [[play](https://go.dev/play/p/9xP8rN0vz--)]
@@ -1049,6 +1091,10 @@ import "github.com/duke-git/lancet/v2/strutil"
 -   **<big>Unwrap</big>** : 从另一个字符串中解开一个给定的字符串。 将更改源字符串。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/strutil_zh-CN.md#Unwrap)]
    [[play](https://go.dev/play/p/Ec2q4BzCpG-)]
+-   **<big>SplitWords</big>** : 将字符串拆分为单词，只支持字母字符单词。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/strutil_zh-CN.md#SplitWords)]
+-   **<big>WordCount</big>** : 返回有意义单词的数量，只支持字母字符单词。
+    [[doc](https://github.com/duke-git/lancet/blob/main/docs/strutil_zh-CN.md#WordCount)]

 ### 18. system 包含 os, runtime, shell command 的相关函数。

@@ -1190,31 +1236,43 @@ import "github.com/duke-git/lancet/v2/xerror"

 -   **<big>New</big>** : 创建XError对象实例。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror_zh-CN.md#New)]
+    [[play](https://go.dev/play/p/w4oWZts7q7f)]
 -   **<big>Wrap</big>** : 根据error对象创建XError对象实例，可添加message。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror_zh-CN.md#Wrap)]
+    [[play](https://go.dev/play/p/5385qT2dCi4)]
 -   **<big>Unwrap</big>** : 从error对象中解构出XError。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror_zh-CN.md#Unwrap)]
+    [[play](https://go.dev/play/p/LKMLep723tu)]
 -   **<big>XError_Wrap</big>** : 创建新的XError对象并将消息和id复制到新的对象中。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror_zh-CN.md#XError_Wrap)]
+    [[play](https://go.dev/play/p/5385qT2dCi4)]
 -   **<big>XError_Unwrap</big>** : 解构XEerror为error对象。适配github.com/pkg/errors。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror_zh-CN.md#XError_Unwrap)]
+    [[play](https://go.dev/play/p/VUXJ8BST4c6)]
 -   **<big>XError_With</big>** : 添加与XError对象的键和值。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror_zh-CN.md#XError_With)]
+    [[play](https://go.dev/play/p/ow8UISXX_Dp)]
 -   **<big>XError_Id</big>** : 设置XError对象的id。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror_zh-CN.md#XError_Id)]
+    [[play](https://go.dev/play/p/X6HBlsy58U9)]
 -   **<big>XError_Is</big>** : 检查目标error是否为XError，两个错误中的error.id是否匹配。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror_zh-CN.md#XError_Is)]
+    [[play](https://go.dev/play/p/X6HBlsy58U9)]
 -   **<big>XError_Values</big>** : 返回由With设置的键和值的映射。将合并所有XError键和值。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror_zh-CN.md#XError_Values)]
+    [[play](https://go.dev/play/p/ow8UISXX_Dp)]
 -   **<big>XError_StackTrace</big>** : 返回与pkg/error兼容的堆栈信息。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror_zh-CN.md#XError_StackTrace)]
+    [[play](https://go.dev/play/p/6FAvSQpa7pc)]
 -   **<big>XError_Info</big>** : 返回可打印的XError对象信息。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror_zh-CN.md#XError_Info)]
+    [[play](https://go.dev/play/p/1ZX0ME1F-Jb)]
 -   **<big>XError_Error</big>** : 实现标准库的error接口。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror_zh-CN.md#XError_Error)]
+    [[play](https://go.dev/play/p/w4oWZts7q7f)]
 -   **<big>TryUnwrap</big>** : 检查error, 如果err为nil则展开，则它返回一个有效值，如果err不是nil则Unwrap使用err发生panic。
    [[doc](https://github.com/duke-git/lancet/blob/main/docs/xerror_zh-CN.md#TryUnwrap)]
-    [[play](https://go.dev/play/p/w84d7Mb3Afk)]
+    [[play](https://go.dev/play/p/acyZVkNZEeW)]
    

 ## 如何贡献代码
--- a/convertor/convertor.go
+++ b/convertor/convertor.go
@@ -9,6 +9,7 @@ import (
 	"encoding/binary"
 	"encoding/gob"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"math"
 	"reflect"
@@ -327,7 +328,7 @@ func DecodeByte(data []byte, target any) error {

 // DeepClone creates a deep copy of passed item.
 // can't clone unexported field of struct
-// Play: todo
+// Play: https://go.dev/play/p/j4DP5dquxnk
 func DeepClone[T any](src T) T {
 	c := cloner{
 		ptrs: map[reflect.Type]map[uintptr]reflect.Value{},
@@ -340,3 +341,46 @@ func DeepClone[T any](src T) T {

 	return result.Interface().(T)
 }
+
+// CopyProperties copies each field from the source into the destination. It recursively copies struct pointers and interfaces that contain struct pointers.
+// Play: todo
+func CopyProperties[T, U any](dst T, src U) (err error) {
+	defer func() {
+		if e := recover(); e != nil {
+			err = errors.New(fmt.Sprintf("%v", e))
+		}
+	}()
+
+	dstType, dstValue := reflect.TypeOf(dst), reflect.ValueOf(dst)
+	srcType, srcValue := reflect.TypeOf(src), reflect.ValueOf(src)
+
+	if dstType.Kind() != reflect.Ptr || dstType.Elem().Kind() != reflect.Struct {
+		return errors.New("CopyProperties: param dst should be struct pointer")
+	}
+
+	if srcType.Kind() == reflect.Ptr {
+		srcType, srcValue = srcType.Elem(), srcValue.Elem()
+	}
+	if srcType.Kind() != reflect.Struct {
+		return errors.New("CopyProperties: param src should be a struct or struct pointer")
+	}
+
+	dstType, dstValue = dstType.Elem(), dstValue.Elem()
+
+	propertyNums := dstType.NumField()
+
+	for i := 0; i < propertyNums; i++ {
+		property := dstType.Field(i)
+		propertyValue := srcValue.FieldByName(property.Name)
+
+		if !propertyValue.IsValid() || property.Type != propertyValue.Type() {
+			continue
+		}
+
+		if dstValue.Field(i).CanSet() {
+			dstValue.Field(i).Set(propertyValue)
+		}
+	}
+
+	return nil
+}
--- a/convertor/convertor_example_test.go
+++ b/convertor/convertor_example_test.go
@@ -295,3 +295,45 @@ func ExampleDeepClone() {
 	// map[a:1 b:2] false
 	// &{test 1 0.1 true <nil> } false
 }
+
+func ExampleCopyProperties() {
+	type Address struct {
+		Country string
+		ZipCode string
+	}
+
+	type User struct {
+		Name   string
+		Age    int
+		Role   string
+		Addr   Address
+		Hobbys []string
+		salary int
+	}
+
+	type Employee struct {
+		Name   string
+		Age    int
+		Role   string
+		Addr   Address
+		Hobbys []string
+		salary int
+	}
+
+	user := User{Name: "user001", Age: 10, Role: "Admin", Addr: Address{Country: "CN", ZipCode: "001"}, Hobbys: []string{"a", "b"}, salary: 1000}
+
+	employee1 := Employee{}
+	CopyProperties(&employee1, &user)
+
+	employee2 := Employee{Name: "employee001", Age: 20, Role: "User",
+		Addr: Address{Country: "UK", ZipCode: "002"}, salary: 500}
+
+	CopyProperties(&employee2, &user)
+
+	fmt.Println(employee1)
+	fmt.Println(employee2)
+
+	// Output:
+	// {user001 10 Admin {CN 001} [a b] 0}
+	// {user001 10 Admin {CN 001} [a b] 500}
+}
--- a/convertor/convertor_test.go
+++ b/convertor/convertor_test.go
@@ -298,3 +298,53 @@ func TestDeepClone(t *testing.T) {
 		}
 	}
 }
+
+func TestCopyProperties(t *testing.T) {
+	assert := internal.NewAssert(t, "TestCopyProperties")
+
+	type Address struct {
+		Country string
+		ZipCode string
+	}
+
+	type User struct {
+		Name   string
+		Age    int
+		Role   string
+		Addr   Address
+		Hobbys []string
+		salary int
+	}
+
+	type Employee struct {
+		Name   string
+		Age    int
+		Role   string
+		Addr   Address
+		Hobbys []string
+		salary int
+	}
+
+	user := User{Name: "user001", Age: 10, Role: "Admin", Addr: Address{Country: "CN", ZipCode: "001"}, Hobbys: []string{"a", "b"}, salary: 1000}
+
+	employee1 := Employee{}
+
+	err := CopyProperties(&employee1, &user)
+
+	assert.IsNil(err)
+	assert.Equal("user001", employee1.Name)
+	assert.Equal("Admin", employee1.Role)
+	assert.Equal("CN", employee1.Addr.Country)
+	assert.Equal(0, employee1.salary)
+
+	employee2 := Employee{Name: "employee001", Age: 20, Role: "User",
+		Addr: Address{Country: "UK", ZipCode: "002"}, salary: 500}
+
+	err = CopyProperties(&employee2, &user)
+
+	assert.IsNil(err)
+	assert.Equal("user001", employee2.Name)
+	assert.Equal("Admin", employee2.Role)
+	assert.Equal("CN", employee2.Addr.Country)
+	assert.Equal(500, employee2.salary)
+}
--- a/docs/convertor.md
+++ b/docs/convertor.md
@@ -39,6 +39,7 @@ import (
 -   [EncodeByte](#EncodeByte)
 -   [DecodeByte](#DecodeByte)
 -   [DeepClone](#DeepClone)
+-   [CopyProperties](#CopyProperties)

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

@@ -651,44 +652,108 @@ import (

 func main() {
    type Struct struct {
-		Str        string
-		Int        int
-		Float      float64
-		Bool       bool
-		Nil        interface{}
-		unexported string
-	}
+        Str        string
+        Int        int
+        Float      float64
+        Bool       bool
+        Nil        interface{}
+        unexported string
+    }

-	cases := []interface{}{
-		true,
-		1,
-		0.1,
-		map[string]int{
-			"a": 1,
-			"b": 2,
-		},
-		&Struct{
-			Str:   "test",
-			Int:   1,
-			Float: 0.1,
-			Bool:  true,
-			Nil:   nil,
-			// unexported: "can't be cloned",
-		},
-	}
+    cases := []interface{}{
+        true,
+        1,
+        0.1,
+        map[string]int{
+            "a": 1,
+            "b": 2,
+        },
+        &Struct{
+            Str:   "test",
+            Int:   1,
+            Float: 0.1,
+            Bool:  true,
+            Nil:   nil,
+            // unexported: "can't be cloned",
+        },
+    }

-	for _, item := range cases {
-		cloned := convertor.DeepClone(item)
+    for _, item := range cases {
+        cloned := convertor.DeepClone(item)

-		isPointerEqual := &cloned == &item
-		fmt.Println(cloned, isPointerEqual)
-	}
+        isPointerEqual := &cloned == &item
+        fmt.Println(cloned, isPointerEqual)
+    }

-	// Output:
-	// true false
-	// 1 false
-	// 0.1 false
-	// map[a:1 b:2] false
-	// &{test 1 0.1 true <nil> } false
+    // Output:
+    // true false
+    // 1 false
+    // 0.1 false
+    // map[a:1 b:2] false
+    // &{test 1 0.1 true <nil> } false
+}
+```
+
+
+### <span id="CopyProperties">CopyProperties</span>
+
+<p>Copies each field from the source struct into the destination struct.</p>
+
+<b>Signature:</b>
+
+```go
+func CopyProperties[T, U any](dst T, src U) (err error)
+```
+
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/convertor"
+)
+
+func main() {
+    type Address struct {
+        Country string
+        ZipCode string
+    }
+
+    type User struct {
+        Name   string
+        Age    int
+        Role   string
+        Addr   Address
+        Hobbys []string
+        salary int
+    }
+
+    type Employee struct {
+        Name   string
+        Age    int
+        Role   string
+        Addr   Address
+        Hobbys []string
+        salary int
+    }
+
+    user := User{Name: "user001", Age: 10, Role: "Admin", Addr: Address{Country: "CN", ZipCode: "001"}, Hobbys: []string{"a", "b"}, salary: 1000}
+
+    employee1 := Employee{}
+    CopyProperties(&employee1, &user)
+
+    employee2 := Employee{Name: "employee001", Age: 20, Role: "User",
+        Addr: Address{Country: "UK", ZipCode: "002"}, salary: 500}
+
+    CopyProperties(&employee2, &user)
+
+    fmt.Println(employee1)
+    fmt.Println(employee2)
+
+    // Output:
+    // {user001 10 Admin {CN 001} [a b] 0}
+    // {user001 10 Admin {CN 001} [a b] 500}
 }
 ```
--- a/docs/convertor_zh-CN.md
+++ b/docs/convertor_zh-CN.md
@@ -39,6 +39,8 @@ import (
 -   [EncodeByte](#EncodeByte)
 -   [DecodeByte](#DecodeByte)
 -   [DeepClone](#DeepClone)
+-   [CopyProperties](#CopyProperties)
+

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

@@ -650,44 +652,107 @@ import (

 func main() {
    type Struct struct {
-		Str        string
-		Int        int
-		Float      float64
-		Bool       bool
-		Nil        interface{}
-		unexported string
-	}
+        Str        string
+        Int        int
+        Float      float64
+        Bool       bool
+        Nil        interface{}
+        unexported string
+    }

-	cases := []interface{}{
-		true,
-		1,
-		0.1,
-		map[string]int{
-			"a": 1,
-			"b": 2,
-		},
-		&Struct{
-			Str:   "test",
-			Int:   1,
-			Float: 0.1,
-			Bool:  true,
-			Nil:   nil,
-			// unexported: "can't be cloned",
-		},
-	}
+    cases := []interface{}{
+        true,
+        1,
+        0.1,
+        map[string]int{
+            "a": 1,
+            "b": 2,
+        },
+        &Struct{
+            Str:   "test",
+            Int:   1,
+            Float: 0.1,
+            Bool:  true,
+            Nil:   nil,
+            // unexported: "can't be cloned",
+        },
+    }

-	for _, item := range cases {
-		cloned := convertor.DeepClone(item)
+    for _, item := range cases {
+        cloned := convertor.DeepClone(item)

-		isPointerEqual := &cloned == &item
-		fmt.Println(cloned, isPointerEqual)
-	}
+        isPointerEqual := &cloned == &item
+        fmt.Println(cloned, isPointerEqual)
+    }

-	// Output:
-	// true false
-	// 1 false
-	// 0.1 false
-	// map[a:1 b:2] false
-	// &{test 1 0.1 true <nil> } false
+    // Output:
+    // true false
+    // 1 false
+    // 0.1 false
+    // map[a:1 b:2] false
+    // &{test 1 0.1 true <nil> } false
+}
+```
+
+### <span id="CopyProperties">CopyProperties</span>
+
+<p>拷贝不同结构体之间的同名字段。</p>
+
+<b>函数签名:</b>
+
+```go
+func CopyProperties[T, U any](dst T, src U) (err error)
+```
+
+<b>示例:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/convertor"
+)
+
+func main() {
+    type Address struct {
+        Country string
+        ZipCode string
+    }
+
+    type User struct {
+        Name   string
+        Age    int
+        Role   string
+        Addr   Address
+        Hobbys []string
+        salary int
+    }
+
+    type Employee struct {
+        Name   string
+        Age    int
+        Role   string
+        Addr   Address
+        Hobbys []string
+        salary int
+    }
+
+    user := User{Name: "user001", Age: 10, Role: "Admin", Addr: Address{Country: "CN", ZipCode: "001"}, Hobbys: []string{"a", "b"}, salary: 1000}
+
+    employee1 := Employee{}
+    CopyProperties(&employee1, &user)
+
+    employee2 := Employee{Name: "employee001", Age: 20, Role: "User",
+        Addr: Address{Country: "UK", ZipCode: "002"}, salary: 500}
+
+    CopyProperties(&employee2, &user)
+
+    fmt.Println(employee1)
+    fmt.Println(employee2)
+
+    // Output:
+    // {user001 10 Admin {CN 001} [a b] 0}
+    // {user001 10 Admin {CN 001} [a b] 500}
 }
 ```
--- a/docs/function.md
+++ b/docs/function.md
@@ -29,6 +29,7 @@ import (
 -   [Compose](#Compose)
 -   [Debounced](#Debounced)
 -   [Delay](#Delay)
+-   [Schedule](#Schedule)
 -   [Pipeline](#Pipeline)
 -   [Watcher](#Watcher)

--- a/docs/function_zh-CN.md
+++ b/docs/function_zh-CN.md
@@ -29,6 +29,7 @@ import (
 -   [Compose](#Compose)
 -   [Debounced](#Debounced)
 -   [Delay](#Delay)
+-   [Schedule](#Schedule)
 -   [Pipeline](#Pipeline)
 -   [Watcher](#Watcher)

@@ -206,7 +207,7 @@ import (

 func main() {
    count := 0
-    
+
    add := func() {
        count++
    }
--- a/docs/maputil.md
+++ b/docs/maputil.md
@@ -24,11 +24,23 @@ import (

 -   [ForEach](#ForEach)
 -   [Filter](#Filter)
+-   [FilterByKeys](#FilterByKeys)
+-   [FilterByValues](#FilterByValues)
+-   [OmitBy](#OmitBy)
+-   [OmitByKeys](#OmitByKeys)
+-   [OmitByValues](#OmitByValues)
 -   [Intersect](#Intersect)
 -   [Keys](#Keys)
+-   [Values](#Values)
+-   [KeysBy](#KeysBy)
+-   [ValuesBy](#ValuesBy)
+-   [MapKeys](#MapKeys)
+-   [MapValues](#MapValues)
+-   [Entries](#Entries)
+-   [FromEntries](#FromEntries)
+-   [Transform](#Transform)
 -   [Merge](#Merge)
 -   [Minus](#Minus)
-   [Values](#Values)
 -   [IsDisjoint](#IsDisjoint)

 <div STYLE="page-break-after: always;"></div>
@@ -121,6 +133,205 @@ func main() {
 }
 ```

+
+### <span id="FilterByKeys">FilterByKeys</span>
+
+<p>Iterates over map, return a new map whose keys are all given keys.</p>
+
+<b>Signature:</b>
+
+```go
+func FilterByKeys[K comparable, V any](m map[K]V, keys []K) 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,
+    }
+
+    result := maputil.FilterByKeys(m, []string{"a", "b"})
+
+    fmt.Println(result)
+
+    // Output:
+    // map[a:1 b:2]
+}
+```
+
+
+### <span id="FilterByValues">FilterByValues</span>
+
+<p>Iterates over map, return a new map whose values are all given values.</p>
+
+<b>Signature:</b>
+
+```go
+func FilterByValues[K comparable, V comparable](m map[K]V, values []V) 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,
+    }
+
+    result := maputil.FilterByValues(m, []int{3, 4})
+
+    fmt.Println(result)
+
+    // Output:
+    // map[c:3 d:4]
+}
+```
+
+
+### <span id="OmitBy">OmitBy</span>
+
+<p>OmitBy is the opposite of Filter, removes all the map elements for which the predicate function returns true.</p>
+
+<b>Signature:</b>
+
+```go
+func OmitBy[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
+    }
+
+    result := maputil.OmitBy(m, isEven)
+
+    fmt.Println(result)
+
+    // Output:
+    // map[a:1 c:3 e:5]
+}
+```
+
+
+### <span id="OmitByKeys">OmitByKeys</span>
+
+<p>The opposite of FilterByKeys, extracts all the map elements which keys are not omitted.</p>
+
+<b>Signature:</b>
+
+```go
+func OmitByKeys[K comparable, V any](m map[K]V, keys []K) 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,
+    }
+
+    result := maputil.OmitByKeys(m, []string{"a", "b"})
+
+    fmt.Println(result)
+
+    // Output:
+    // map[c:3 d:4 e:5]
+}
+```
+
+
+### <span id="OmitByValues">OmitByValues</span>
+
+<p>The opposite of FilterByValues. remov all elements whose value are in the give slice.</p>
+
+<b>Signature:</b>
+
+```go
+func OmitByValues[K comparable, V comparable](m map[K]V, values []V) 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,
+    }
+
+    result := maputil.OmitByValues(m, []int{4, 5})
+
+    fmt.Println(result)
+
+    // Output:
+    // map[a:1 b:2 c:3]
+}
+```
+
+
 ### <span id="Intersect">Intersect</span>

 <p>Iterates over maps, return a new map of key and value pairs in all given maps.</p>
@@ -193,6 +404,7 @@ package main

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

@@ -313,6 +525,7 @@ package main

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

@@ -335,6 +548,300 @@ func main() {
 }
 ```

+### <span id="KeysBy">KeysBy</span>
+
+<p>Creates a slice whose element is the result of function mapper invoked by every map's key.</p>
+
+<b>Signature:</b>
+
+```go
+func KeysBy[K comparable, V any, T any](m map[K]V, mapper func(item K) T) []T
+```
+
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "sort"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+    m := map[int]string{
+        1: "a",
+        2: "a",
+        3: "b",
+    }
+
+    keys := maputil.KeysBy(m, func(n int) int {
+        return n + 1
+    })
+
+    sort.Ints(keys)
+
+    fmt.Println(keys)
+
+    // Output:
+    // [2 3 4]
+}
+```
+
+### <span id="ValuesBy">ValuesBy</span>
+
+<p>Creates a slice whose element is the result of function mapper invoked by every map's value.</p>
+
+<b>Signature:</b>
+
+```go
+func ValuesBy[K comparable, V any, T any](m map[K]V, mapper func(item V) T) []T
+```
+
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "sort"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+    m := map[int]string{
+        1: "a",
+        2: "b",
+        3: "c",
+    }
+    values := maputil.ValuesBy(m, func(v string) string {
+        switch v {
+        case "a":
+            return "a-1"
+        case "b":
+            return "b-2"
+        case "c":
+            return "c-3"
+        default:
+            return ""
+        }
+    })
+
+    sort.Strings(values)
+
+    fmt.Println(values)
+
+    // Output:
+    // [a-1 b-2 c-3]
+}
+```
+
+
+### <span id="MapKeys">MapKeys</span>
+
+<p>Transforms a map to other type map by manipulating it's keys.</p>
+
+<b>Signature:</b>
+
+```go
+func MapKeys[K comparable, V any, T comparable](m map[K]V, iteratee func(key K, value V) T) map[T]V
+```
+
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "strconv"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+    m := map[int]string{
+        1: "a",
+        2: "b",
+        3: "c",
+    }
+
+    result := maputil.MapKeys(m, func(k int, _ string) string {
+        return strconv.Itoa(k)
+    })
+
+    fmt.Println(result)
+
+    // Output:
+    // map[1:a 2:b 3:c]
+}
+```
+
+### <span id="MapValues">MapValues</span>
+
+<p>Transforms a map to other type map by manipulating it's values.</p>
+
+<b>Signature:</b>
+
+```go
+func MapValues[K comparable, V any, T any](m map[K]V, iteratee func(key K, value V) T) map[K]T
+```
+
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "strconv"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+    m := map[int]string{
+        1: "a",
+        2: "b",
+        3: "c",
+    }
+
+    result := maputil.MapValues(m, func(k int, v string) string {
+        return v + strconv.Itoa(k)
+    })
+
+    fmt.Println(result)
+
+    // Output:
+    // map[1:a1 2:b2 3:c3]
+}
+```
+
+
+### <span id="Entry">Entry</span>
+
+<p>Transforms a map into array of key/value pairs.</p>
+
+<b>Signature:</b>
+
+```go
+type Entry[K comparable, V any] struct {
+    Key   K
+    Value V
+}
+func Entries[K comparable, V any](m map[K]V) []Entry[K, V]
+```
+
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "sort"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+    m := map[string]int{
+        "a": 1,
+        "b": 2,
+        "c": 3,
+    }
+
+    result := maputil.Entries(m)
+
+    sort.Slice(result, func(i, j int) bool {
+        return result[i].Value < result[j].Value
+    })
+
+    fmt.Println(result)
+
+    // Output:
+    // [{a 1} {b 2} {c 3}]
+}
+```
+
+
+### <span id="FromEntries">FromEntries</span>
+
+<p>Creates a map based on a slice of key/value pairs.</p>
+
+<b>Signature:</b>
+
+```go
+type Entry[K comparable, V any] struct {
+    Key   K
+    Value V
+}
+func FromEntries[K comparable, V any](entries []Entry[K, V]) map[K]V
+```
+
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+    result := maputil.FromEntries([]Entry[string, int]{
+        {Key: "a", Value: 1},
+        {Key: "b", Value: 2},
+        {Key: "c", Value: 3},
+    })
+
+    fmt.Println(result)
+
+    // Output:
+    // map[a:1 b:2 c:3]
+}
+```
+
+### <span id="Transform">Transform</span>
+
+<p>Transform a map to another type map.</p>
+
+<b>Signature:</b>
+
+```go
+func Transform[K1 comparable, V1 any, K2 comparable, V2 any](m map[K1]V1, iteratee func(key K1, value V1) (K2, V2)) map[K2]V2
+```
+
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "strconv"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+    m := map[string]int{
+        "a": 1,
+        "b": 2,
+        "c": 3,
+    }
+
+    result := Transform(m, func(k string, v int) (string, string) {
+        return k, strconv.Itoa(v)
+    })
+
+    fmt.Println(result)
+
+    // Output:
+    // map[a:1 b:2 c:3]
+}
+```
+
+
 ### <span id="IsDisjoint">IsDisjoint</span>

 <p>Checks two maps are disjoint if they have no keys in common</p>
--- a/docs/maputil_zh-CN.md
+++ b/docs/maputil_zh-CN.md
@@ -24,11 +24,23 @@ import (

 -   [ForEach](#ForEach)
 -   [Filter](#Filter)
+-   [FilterByKeys](#FilterByKeys)
+-   [FilterByValues](#FilterByValues)
+-   [OmitBy](#OmitBy)
+-   [OmitByKeys](#OmitByKeys)
+-   [OmitByValues](#OmitByValues)
 -   [Intersect](#Intersect)
 -   [Keys](#Keys)
+-   [Values](#Values)
+-   [KeysBy](#KeysBy)
+-   [ValuesBy](#ValuesBy)
+-   [MapKeys](#MapKeys)
+-   [MapValues](#MapValues)
+-   [Entries](#Entries)
+-   [FromEntries](#FromEntries)
+-   [Transform](#Transform)
 -   [Merge](#Merge)
 -   [Minus](#Minus)
-   [Values](#Values)
 -   [IsDisjoint](#IsDisjoint)

 <div STYLE="page-break-after: always;"></div>
@@ -78,7 +90,7 @@ func main() {

 ### <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>
+<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>

@@ -121,6 +133,203 @@ func main() {
 }
 ```

+### <span id="FilterByKeys">FilterByKeys</span>
+
+<p>迭代map, 返回一个新map，其key都是给定的key值。</p>
+
+<b>函数签名:</b>
+
+```go
+func FilterByKeys[K comparable, V any](m map[K]V, keys []K) map[K]V
+```
+
+<b>示例:</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,
+    }
+
+    result := maputil.FilterByKeys(m, []string{"a", "b"})
+
+    fmt.Println(result)
+
+    // Output:
+    // map[a:1 b:2]
+}
+```
+
+
+### <span id="FilterByValues">FilterByValues</span>
+
+<p>迭代map, 返回一个新map，其value都是给定的value值。</p>
+
+<b>函数签名:</b>
+
+```go
+func FilterByValues[K comparable, V comparable](m map[K]V, values []V) map[K]V
+```
+
+<b>示例:</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,
+    }
+
+    result := maputil.FilterByValues(m, []int{3, 4})
+
+    fmt.Println(result)
+
+    // Output:
+    // map[c:3 d:4]
+}
+```
+
+
+### <span id="OmitBy">OmitBy</span>
+
+<p>Filter的反向操作, 迭代map中的每对key和value, 删除符合predicate函数的key, value, 返回新map。</p>
+
+<b>函数签名:</b>
+
+```go
+func OmitBy[K comparable, V any](m map[K]V, predicate func(key K, value V) bool) map[K]V
+```
+
+<b>示例:</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
+    }
+
+    result := maputil.OmitBy(m, isEven)
+
+    fmt.Println(result)
+
+    // Output:
+    // map[a:1 c:3 e:5]
+}
+```
+
+
+### <span id="OmitByKeys">OmitByKeys</span>
+
+<p>FilterByKeys的反向操作, 迭代map, 返回一个新map，其key不包括给定的key值。</p>
+
+<b>函数签名:</b>
+
+```go
+func OmitByKeys[K comparable, V any](m map[K]V, keys []K) map[K]V
+```
+
+<b>示例:</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,
+    }
+
+    result := maputil.OmitByKeys(m, []string{"a", "b"})
+
+    fmt.Println(result)
+
+    // Output:
+    // map[c:3 d:4 e:5]
+}
+```
+
+
+### <span id="OmitByValues">OmitByValues</span>
+
+<p>FilterByValues的反向操作, 迭代map, 返回一个新map，其value不包括给定的value值。</p>
+
+<b>函数签名:</b>
+
+```go
+func OmitByValues[K comparable, V comparable](m map[K]V, values []V) map[K]V
+```
+
+<b>示例:</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,
+    }
+
+    result := maputil.OmitByValues(m, []int{4, 5})
+
+    fmt.Println(result)
+
+    // Output:
+    // map[a:1 b:2 c:3]
+}
+```
+
 ### <span id="Intersect">Intersect</span>

 <p>多个map的交集操作</p>
@@ -333,6 +542,299 @@ func main() {
 }
 ```

+### <span id="KeysBy">KeysBy</span>
+
+<p>创建一个切片，其元素是每个map的key调用mapper函数的结果。</p>
+
+<b>函数签名:</b>
+
+```go
+func KeysBy[K comparable, V any, T any](m map[K]V, mapper func(item K) T) []T
+```
+
+<b>示例:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "sort"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+    m := map[int]string{
+        1: "a",
+        2: "a",
+        3: "b",
+    }
+
+    keys := maputil.KeysBy(m, func(n int) int {
+        return n + 1
+    })
+
+    sort.Ints(keys)
+
+    fmt.Println(keys)
+
+    // Output:
+    // [2 3 4]
+}
+```
+
+### <span id="ValuesBy">ValuesBy</span>
+
+<p>创建一个切片，其元素是每个map的value调用mapper函数的结果。</p>
+
+<b>函数签名:</b>
+
+```go
+func ValuesBy[K comparable, V any, T any](m map[K]V, mapper func(item V) T) []T
+```
+
+<b>示例:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "sort"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+    m := map[int]string{
+        1: "a",
+        2: "b",
+        3: "c",
+    }
+    values := maputil.ValuesBy(m, func(v string) string {
+        switch v {
+        case "a":
+            return "a-1"
+        case "b":
+            return "b-2"
+        case "c":
+            return "c-3"
+        default:
+            return ""
+        }
+    })
+
+    sort.Strings(values)
+
+    fmt.Println(values)
+
+    // Output:
+    // [a-1 b-2 c-3]
+}
+```
+
+
+### <span id="MapKeys">MapKeys</span>
+
+<p>操作map的每个key，然后转为新的map。</p>
+
+<b>函数签名:</b>
+
+```go
+func MapKeys[K comparable, V any, T comparable](m map[K]V, iteratee func(key K, value V) T) map[T]V
+```
+
+<b>示例:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "strconv"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+    m := map[int]string{
+        1: "a",
+        2: "b",
+        3: "c",
+    }
+
+    result := maputil.MapKeys(m, func(k int, _ string) string {
+        return strconv.Itoa(k)
+    })
+
+    fmt.Println(result)
+
+    // Output:
+    // map[1:a 2:b 3:c]
+}
+```
+
+### <span id="MapValues">MapValues</span>
+
+<p>操作map的每个value，然后转为新的map。</p>
+
+<b>函数签名:</b>
+
+```go
+func MapValues[K comparable, V any, T any](m map[K]V, iteratee func(key K, value V) T) map[K]T
+```
+
+<b>示例:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "strconv"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+    m := map[int]string{
+        1: "a",
+        2: "b",
+        3: "c",
+    }
+
+    result := maputil.MapValues(m, func(k int, v string) string {
+        return v + strconv.Itoa(k)
+    })
+
+    fmt.Println(result)
+
+    // Output:
+    // map[1:a1 2:b2 3:c3]
+}
+```
+
+
+### <span id="Entry">Entry</span>
+
+<p>将map转换为键/值对切片。</p>
+
+<b>函数签名:</b>
+
+```go
+type Entry[K comparable, V any] struct {
+    Key   K
+    Value V
+}
+func Entries[K comparable, V any](m map[K]V) []Entry[K, V]
+```
+
+<b>示例:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "sort"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+    m := map[string]int{
+        "a": 1,
+        "b": 2,
+        "c": 3,
+    }
+
+    result := maputil.Entries(m)
+
+    sort.Slice(result, func(i, j int) bool {
+        return result[i].Value < result[j].Value
+    })
+
+    fmt.Println(result)
+
+    // Output:
+    // [{a 1} {b 2} {c 3}]
+}
+```
+
+
+### <span id="FromEntries">FromEntries</span>
+
+<p>基于键/值对的切片创建map。</p>
+
+<b>函数签名:</b>
+
+```go
+type Entry[K comparable, V any] struct {
+    Key   K
+    Value V
+}
+func FromEntries[K comparable, V any](entries []Entry[K, V]) map[K]V
+```
+
+<b>示例:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+    result := maputil.FromEntries([]Entry[string, int]{
+        {Key: "a", Value: 1},
+        {Key: "b", Value: 2},
+        {Key: "c", Value: 3},
+    })
+
+    fmt.Println(result)
+
+    // Output:
+    // map[a:1 b:2 c:3]
+}
+```
+
+### <span id="Transform">Transform</span>
+
+<p>将map转换为其他类型的map。</p>
+
+<b>函数签名:</b>
+
+```go
+func Transform[K1 comparable, V1 any, K2 comparable, V2 any](m map[K1]V1, iteratee func(key K1, value V1) (K2, V2)) map[K2]V2
+```
+
+<b>示例:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "strconv"
+    "github.com/duke-git/lancet/v2/maputil"
+)
+
+func main() {
+    m := map[string]int{
+        "a": 1,
+        "b": 2,
+        "c": 3,
+    }
+
+    result := Transform(m, func(k string, v int) (string, string) {
+        return k, strconv.Itoa(v)
+    })
+
+    fmt.Println(result)
+
+    // Output:
+    // map[a:1 b:2 c:3]
+}
+```
+
 ### <span id="IsDisjoint">IsDisjoint</span>

 <p>验证两个map是否具有不同的key</p>
--- a/docs/slice.md
+++ b/docs/slice.md
@@ -24,6 +24,7 @@ import (

 -   [AppendIfAbsent](#AppendIfAbsent)
 -   [Contain](#Contain)
+-   [ContainBy](#ContainBy)
 -   [ContainSubSlice](#ContainSubSlice)
 -   [Chunk](#Chunk)
 -   [Compact](#Compact)
@@ -56,6 +57,8 @@ import (
 -   [IndexOf](#IndexOf)
 -   [LastIndexOf](#LastIndexOf)
 -   [Map](#Map)
+-   [FilterMap](#FilterMap)
+-   [FlatMap](#FlatMap)
 -   [Merge](#Merge)
 -   [Reverse](#Reverse)
 -   [Reduce](#Reduce)
@@ -149,6 +152,51 @@ func main() {
 }
 ```

+### <span id="ContainBy">ContainBy</span>
+
+<p>returns true if predicate function return true.</p>
+
+<b>Signature:</b>
+
+```go
+func ContainBy[T any](slice []T, predicate func(item T) bool) bool
+```
+
+<b>Example:</b>
+
+```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
+}
+```
+
 ### <span id="ContainSubSlice">ContainSubSlice</span>

 <p>Check if the slice contain subslice or not.</p>
@@ -1252,6 +1300,76 @@ func main() {
 }
 ```

+### <span id="FilterMap">FilterMap</span>
+
+<p>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.</p>
+
+<b>Signature:</b>
+
+```go
+func FilterMap[T any, U any](slice []T, iteratee func(index int, item T) (U, bool)) []U
+```
+
+<b>Example:</b>
+
+```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"}
+}
+```
+
+### <span id="FlatMap">FlatMap</span>
+
+<p>Manipulates a slice and transforms and flattens it to a slice of another type.</p>
+
+<b>Signature:</b>
+
+```go
+func FlatMap[T any, U any](slice []T, iteratee func(index int, item T) []U) []U
+```
+
+<b>Example:</b>
+
+```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"}
+}
+```
+
 ### <span id="Merge">Merge</span>

 <p>Merge all given slices into one slice.</p>
@@ -1467,8 +1585,8 @@ func main() {
    nums := []int{1, 2, 3, 4, 5}
    result := slice.Shuffle(nums)

-    fmt.Println(res) 
-    
+    fmt.Println(res)
+
    // Output:
    // [3 1 5 4 2] (random order)
 }
--- a/docs/slice_zh-CN.md
+++ b/docs/slice_zh-CN.md
@@ -24,6 +24,7 @@ import (

 -   [AppendIfAbsent](#AppendIfAbsent)
 -   [Contain](#Contain)
+-   [ContainBy](#ContainBy)
 -   [ContainSubSlice](#ContainSubSlice)
 -   [Chunk](#Chunk)
 -   [Compact](#Compact)
@@ -56,6 +57,8 @@ import (
 -   [IndexOf](#IndexOf)
 -   [LastIndexOf](#LastIndexOf)
 -   [Map](#Map)
+-   [FilterMap](#FilterMap)
+-   [FlatMap](#FlatMap)
 -   [Merge](#Merge)
 -   [Reverse](#Reverse)
 -   [Reduce](#Reduce)
@@ -149,6 +152,51 @@ func main() {
 }
 ```

+### <span id="ContainBy">ContainBy</span>
+
+<p>根据predicate函数判断切片是否包含某个值。</p>
+
+<b>函数签名:</b>
+
+```go
+func ContainBy[T any](slice []T, predicate func(item T) bool) bool
+```
+
+<b>示例:</b>
+
+```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
+}
+```
+
 ### <span id="ContainSubSlice">ContainSubSlice</span>

 <p>判断slice是否包含subslice</p>
@@ -1254,6 +1302,76 @@ func main() {
 }
 ```

+### <span id="FilterMap">FilterMap</span>
+
+<p>返回一个将filter和map操作应用于给定切片的切片。 iteratee回调函数应该返回两个值：1，结果值。2，结果值是否应该被包含在返回的切片中。</p>
+
+<b>函数签名:</b>
+
+```go
+func FilterMap[T any, U any](slice []T, iteratee func(index int, item T) (U, bool)) []U
+```
+
+<b>示例:</b>
+
+```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"}
+}
+```
+
+### <span id="FlatMap">FlatMap</span>
+
+<p>将切片转换为其它类型切片。</p>
+
+<b>函数签名:</b>
+
+```go
+func FlatMap[T any, U any](slice []T, iteratee func(index int, item T) []U) []U
+```
+
+<b>示例:</b>
+
+```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"}
+}
+```
+
 ### <span id="Merge">Merge</span>

 <p>合并多个切片（不会消除重复元素).</p>
--- a/docs/strutil.md
+++ b/docs/strutil.md
@@ -33,8 +33,9 @@ import (
 -   [UpperKebabCase](#UpperKebabCase)
 -   [LowerFirst](#LowerFirst)
 -   [UpperFirst](#UpperFirst)
-   [PadEnd](#PadEnd)
+-   [Pad](#Pad)
 -   [PadStart](#PadStart)
+-   [PadEnd](#PadEnd)
 -   [Reverse](#Reverse)
 -   [SnakeCase](#SnakeCase)
 -   [UpperSnakeCase](#UpperSnakeCase)
@@ -42,6 +43,8 @@ import (
 -   [Substring](#Substring)
 -   [Wrap](#Wrap)
 -   [Unwrap](#Unwrap)
+-   [SplitWords](#SplitWords)
+-   [WordCount](#WordCount)

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

@@ -449,6 +452,51 @@ func main() {
 }
 ```

+### <span id="Pad">Pad</span>
+
+<p>Pads string on the left and right side if it's shorter than size.</p>
+
+<b>Signature:</b>
+
+```go
+func Pad(source string, size int, padStr string) string
+```
+
+<b>Example:</b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/strutil"
+)
+
+func main() {
+    result1 := strutil.Pad("foo", 1, "bar")
+    result2 := strutil.Pad("foo", 2, "bar")
+    result3 := strutil.Pad("foo", 3, "bar")
+    result4 := strutil.Pad("foo", 4, "bar")
+    result5 := strutil.Pad("foo", 5, "bar")
+    result6 := strutil.Pad("foo", 6, "bar")
+    result7 := strutil.Pad("foo", 7, "bar")
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+    fmt.Println(result3)
+    fmt.Println(result4)
+    fmt.Println(result5)
+    fmt.Println(result6)
+    fmt.Println(result7)
+    // Output:
+    // foo
+    // foo
+    // foo
+    // foob
+    // bfoob
+    // bfooba
+    // bafooba
+}
+```
+
 ### <span id="PadEnd">PadEnd</span>

 <p>Pads string on the right side if it's shorter than size.</p>
@@ -802,3 +850,91 @@ func main() {
    // *foo*
 }
 ```
+
+
+### <span id="SplitWords">SplitWords</span>
+
+<p>Splits a string into words, word only contains alphabetic characters.</p>
+
+<b>Signature:</b>
+
+```go
+func SplitWords(s string) []string
+```
+
+<b>Example:</b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/strutil"
+)
+
+func main() {
+    result1 := strutil.SplitWords("a word")
+    result2 := strutil.SplitWords("I'am a programmer")
+    result3 := strutil.SplitWords("Bonjour, je suis programmeur")
+    result4 := strutil.SplitWords("a -b-c' 'd'e")
+    result5 := strutil.SplitWords("你好，我是一名码农")
+    result6 := strutil.SplitWords("こんにちは，私はプログラマーです")
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+    fmt.Println(result3)
+    fmt.Println(result4)
+    fmt.Println(result5)
+    fmt.Println(result6)
+
+    // Output:
+    // [a word]
+    // [I'am a programmer]
+    // [Bonjour je suis programmeur]
+    // [a b-c' d'e]
+    // []
+    // []
+}
+```
+
+
+### <span id="WordCount">WordCount</span>
+
+<p>Return the number of meaningful word, word only contains alphabetic characters.</p>
+
+<b>Signature:</b>
+
+```go
+func WordCount(s string) int
+```
+
+<b>Example:</b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/strutil"
+)
+
+func main() {
+    result1 := strutil.WordCount("a word")
+    result2 := strutil.WordCount("I'am a programmer")
+    result3 := strutil.WordCount("Bonjour, je suis programmeur")
+    result4 := strutil.WordCount("a -b-c' 'd'e")
+    result5 := strutil.WordCount("你好，我是一名码农")
+    result6 := strutil.WordCount("こんにちは，私はプログラマーです")
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+    fmt.Println(result3)
+    fmt.Println(result4)
+    fmt.Println(result5)
+    fmt.Println(result6)
+
+    // Output:
+    // 2
+    // 3
+    // 4
+    // 3
+    // 0
+    // 0
+}
+```
--- a/docs/strutil_zh-CN.md
+++ b/docs/strutil_zh-CN.md
@@ -33,6 +33,7 @@ import (
 -   [UpperKebabCase](#UpperKebabCase)
 -   [LowerFirst](#LowerFirst)
 -   [UpperFirst](#UpperFirst)
+-   [Pad](#Pad)
 -   [PadEnd](#PadEnd)
 -   [PadStart](#PadStart)
 -   [Reverse](#Reverse)
@@ -42,6 +43,8 @@ import (
 -   [Substring](#Substring)
 -   [Wrap](#Wrap)
 -   [Unwrap](#Unwrap)
+-   [SplitWords](#SplitWords)
+-   [WordCount](#WordCount)

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

@@ -449,6 +452,51 @@ func main() {
 }
 ```

+### <span id="Pad">Pad</span>
+
+<p>如果字符串长度短于size，则在左右两侧填充字符串。</p>
+
+<b>函数签名:</b>
+
+```go
+func Pad(source string, size int, padStr string) string
+```
+
+<b>示例:</b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/strutil"
+)
+
+func main() {
+    result1 := strutil.Pad("foo", 1, "bar")
+    result2 := strutil.Pad("foo", 2, "bar")
+    result3 := strutil.Pad("foo", 3, "bar")
+    result4 := strutil.Pad("foo", 4, "bar")
+    result5 := strutil.Pad("foo", 5, "bar")
+    result6 := strutil.Pad("foo", 6, "bar")
+    result7 := strutil.Pad("foo", 7, "bar")
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+    fmt.Println(result3)
+    fmt.Println(result4)
+    fmt.Println(result5)
+    fmt.Println(result6)
+    fmt.Println(result7)
+    // Output:
+    // foo
+    // foo
+    // foo
+    // foob
+    // bfoob
+    // bfooba
+    // bafooba
+}
+```
+
 ### <span id="PadEnd">PadEnd</span>

 <p>如果字符串长度短于size，则在右侧填充字符串。</p>
@@ -802,3 +850,90 @@ func main() {
    // *foo*
 }
 ```
+
+### <span id="SplitWords">SplitWords</span>
+
+<p>将字符串拆分为单词，只支持字母字符单词。</p>
+
+<b>函数签名:</b>
+
+```go
+func SplitWords(s string) []string
+```
+
+<b>示例:</b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/strutil"
+)
+
+func main() {
+    result1 := strutil.SplitWords("a word")
+    result2 := strutil.SplitWords("I'am a programmer")
+    result3 := strutil.SplitWords("Bonjour, je suis programmeur")
+    result4 := strutil.SplitWords("a -b-c' 'd'e")
+    result5 := strutil.SplitWords("你好，我是一名码农")
+    result6 := strutil.SplitWords("こんにちは，私はプログラマーです")
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+    fmt.Println(result3)
+    fmt.Println(result4)
+    fmt.Println(result5)
+    fmt.Println(result6)
+
+    // Output:
+    // [a word]
+    // [I'am a programmer]
+    // [Bonjour je suis programmeur]
+    // [a b-c' d'e]
+    // []
+    // []
+}
+```
+
+
+### <span id="WordCount">WordCount</span>
+
+<p>返回有意义单词的数量，只支持字母字符单词。</p>
+
+<b>函数签名:</b>
+
+```go
+func WordCount(s string) int
+```
+
+<b>示例:</b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/strutil"
+)
+
+func main() {
+    result1 := strutil.WordCount("a word")
+    result2 := strutil.WordCount("I'am a programmer")
+    result3 := strutil.WordCount("Bonjour, je suis programmeur")
+    result4 := strutil.WordCount("a -b-c' 'd'e")
+    result5 := strutil.WordCount("你好，我是一名码农")
+    result6 := strutil.WordCount("こんにちは，私はプログラマーです")
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+    fmt.Println(result3)
+    fmt.Println(result4)
+    fmt.Println(result5)
+    fmt.Println(result6)
+
+    // Output:
+    // 2
+    // 3
+    // 4
+    // 3
+    // 0
+    // 0
+}
+```
--- a/docs/xerror.md
+++ b/docs/xerror.md
@@ -133,7 +133,7 @@ func main() {
    err1 := xerror.New("error").With("level", "high")
    wrapErr := errors.Wrap(err1, "oops")

-    err := xerror.Unwrap(err1)
+    err := xerror.Unwrap(wrapErr)

    values := err.Values()
    fmt.Println(values["level"])
@@ -441,7 +441,7 @@ import (
 )

 func main() {
-    err := New("error")
+    err := xerror.New("error")
    fmt.Println(err.Error())

    // Output:
--- a/docs/xerror_zh-CN.md
+++ b/docs/xerror_zh-CN.md
@@ -133,7 +133,7 @@ func main() {
    err1 := xerror.New("error").With("level", "high")
    wrapErr := errors.Wrap(err1, "oops")

-    err := xerror.Unwrap(err1)
+    err := xerror.Unwrap(wrapErr)

    values := err.Values()
    fmt.Println(values["level"])
@@ -441,7 +441,7 @@ import (
 )

 func main() {
-    err := New("error")
+    err := xerror.New("error")
    fmt.Println(err.Error())

    // Output:
--- a/maputil/map.go
+++ b/maputil/map.go
@@ -4,7 +4,11 @@
 // Package maputil includes some functions to manipulate map.
 package maputil

-import "reflect"
+import (
+	"reflect"
+
+	"github.com/duke-git/lancet/v2/slice"
+)

 // Keys returns a slice of the map's keys.
 // Play: https://go.dev/play/p/xNB5bTb97Wd
@@ -34,6 +38,30 @@ func Values[K comparable, V any](m map[K]V) []V {
 	return values
 }

+// KeysBy creates a slice whose element is the result of function mapper invoked by every map's key.
+// Play: todo
+func KeysBy[K comparable, V any, T any](m map[K]V, mapper func(item K) T) []T {
+	keys := make([]T, 0, len(m))
+
+	for k := range m {
+		keys = append(keys, mapper(k))
+	}
+
+	return keys
+}
+
+// ValuesBy creates a slice whose element is the result of function mapper invoked by every map's value.
+// Play: todo
+func ValuesBy[K comparable, V any, T any](m map[K]V, mapper func(item V) T) []T {
+	keys := make([]T, 0, len(m))
+
+	for _, v := range m {
+		keys = append(keys, mapper(v))
+	}
+
+	return keys
+}
+
 // Merge maps, next key will overwrite previous key.
 // Play: https://go.dev/play/p/H95LENF1uB-
 func Merge[K comparable, V any](maps ...map[K]V) map[K]V {
@@ -69,6 +97,71 @@ func Filter[K comparable, V any](m map[K]V, predicate func(key K, value V) bool)
 	return result
 }

+// FilterByKeys iterates over map, return a new map whose keys are all given keys.
+// Play: todo
+func FilterByKeys[K comparable, V any](m map[K]V, keys []K) map[K]V {
+	result := make(map[K]V)
+
+	for k, v := range m {
+		if slice.Contain(keys, k) {
+			result[k] = v
+		}
+	}
+	return result
+}
+
+// FilterByValues iterates over map, return a new map whose values are all given values.
+// Play: todo
+func FilterByValues[K comparable, V comparable](m map[K]V, values []V) map[K]V {
+	result := make(map[K]V)
+
+	for k, v := range m {
+		if slice.Contain(values, v) {
+			result[k] = v
+		}
+	}
+	return result
+}
+
+// OmitBy is the opposite of Filter, removes all the map elements for which the predicate function returns true.
+// Play: todo
+func OmitBy[K comparable, V any](m map[K]V, predicate func(key K, value V) bool) map[K]V {
+	result := make(map[K]V)
+
+	for k, v := range m {
+		if !predicate(k, v) {
+			result[k] = v
+		}
+	}
+	return result
+}
+
+// OmitByKeys the opposite of FilterByKeys, extracts all the map elements which keys are not omitted.
+// Play: todo
+func OmitByKeys[K comparable, V any](m map[K]V, keys []K) map[K]V {
+	result := make(map[K]V)
+
+	for k, v := range m {
+		if !slice.Contain(keys, k) {
+			result[k] = v
+		}
+	}
+	return result
+}
+
+// OmitByValues the opposite of FilterByValues. remov all elements whose value are in the give slice.
+// Play: todo
+func OmitByValues[K comparable, V comparable](m map[K]V, values []V) map[K]V {
+	result := make(map[K]V)
+
+	for k, v := range m {
+		if !slice.Contain(values, v) {
+			result[k] = v
+		}
+	}
+	return result
+}
+
 // Intersect iterates over maps, return a new map of key and value pairs in all given maps.
 // Play: https://go.dev/play/p/Zld0oj3sjcC
 func Intersect[K comparable, V any](maps ...map[K]V) map[K]V {
@@ -126,3 +219,73 @@ func IsDisjoint[K comparable, V any](mapA, mapB map[K]V) bool {
 	}
 	return true
 }
+
+// Entry is a key/value pairs.
+type Entry[K comparable, V any] struct {
+	Key   K
+	Value V
+}
+
+// Entries transforms a map into array of key/value pairs.
+// Play: todo
+func Entries[K comparable, V any](m map[K]V) []Entry[K, V] {
+	entries := make([]Entry[K, V], 0, len(m))
+
+	for k, v := range m {
+		entries = append(entries, Entry[K, V]{
+			Key:   k,
+			Value: v,
+		})
+	}
+
+	return entries
+}
+
+// FromEntries creates a map based on a slice of key/value pairs
+// Play: todo
+func FromEntries[K comparable, V any](entries []Entry[K, V]) map[K]V {
+	result := make(map[K]V, len(entries))
+
+	for _, v := range entries {
+		result[v.Key] = v.Value
+	}
+
+	return result
+}
+
+// Transform a map to another type map.
+// Play: todo
+func Transform[K1 comparable, V1 any, K2 comparable, V2 any](m map[K1]V1, iteratee func(key K1, value V1) (K2, V2)) map[K2]V2 {
+	result := make(map[K2]V2, len(m))
+
+	for k1, v1 := range m {
+		k2, v2 := iteratee(k1, v1)
+		result[k2] = v2
+	}
+
+	return result
+}
+
+// MapKeys transforms a map to other type map by manipulating it's keys.
+// Play: todo
+func MapKeys[K comparable, V any, T comparable](m map[K]V, iteratee func(key K, value V) T) map[T]V {
+	result := make(map[T]V, len(m))
+
+	for k, v := range m {
+		result[iteratee(k, v)] = v
+	}
+
+	return result
+}
+
+// MapValues transforms a map to other type map by manipulating it's values.
+// Play: todo
+func MapValues[K comparable, V any, T any](m map[K]V, iteratee func(key K, value V) T) map[K]T {
+	result := make(map[K]T, len(m))
+
+	for k, v := range m {
+		result[k] = iteratee(k, v)
+	}
+
+	return result
+}
--- a/maputil/map_example_test.go
+++ b/maputil/map_example_test.go
@@ -3,6 +3,7 @@ package maputil
 import (
 	"fmt"
 	"sort"
+	"strconv"
 )

 func ExampleKeys() {
@@ -41,6 +42,51 @@ func ExampleValues() {
 	// [a a b c d]
 }

+func ExampleKeysBy() {
+	m := map[int]string{
+		1: "a",
+		2: "a",
+		3: "b",
+	}
+
+	keys := KeysBy(m, func(n int) int {
+		return n + 1
+	})
+
+	sort.Ints(keys)
+
+	fmt.Println(keys)
+
+	// Output:
+	// [2 3 4]
+}
+
+func ExampleValuesBy() {
+	m := map[int]string{
+		1: "a",
+		2: "b",
+		3: "c",
+	}
+	values := ValuesBy(m, func(v string) string {
+		switch v {
+		case "a":
+			return "a-1"
+		case "b":
+			return "b-2"
+		case "c":
+			return "c-3"
+		default:
+			return ""
+		}
+	})
+
+	sort.Strings(values)
+
+	fmt.Println(values)
+
+	// Output:
+	// [a-1 b-2 c-3]
+}
 func ExampleMerge() {
 	m1 := map[int]string{
 		1: "a",
@@ -99,6 +145,40 @@ func ExampleFilter() {
 	// map[b:2 d:4]
 }

+func ExampleFilterByKeys() {
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+		"d": 4,
+		"e": 5,
+	}
+
+	result := FilterByKeys(m, []string{"a", "b"})
+
+	fmt.Println(result)
+
+	// Output:
+	// map[a:1 b:2]
+}
+
+func ExampleFilterByValues() {
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+		"d": 4,
+		"e": 5,
+	}
+
+	result := FilterByValues(m, []int{3, 4})
+
+	fmt.Println(result)
+
+	// Output:
+	// map[c:3 d:4]
+}
+
 func ExampleIntersect() {
 	m1 := map[string]int{
 		"a": 1,
@@ -179,3 +259,141 @@ func ExampleIsDisjoint() {
 	// true
 	// false
 }
+
+func ExampleEntries() {
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+	}
+
+	result := Entries(m)
+
+	sort.Slice(result, func(i, j int) bool {
+		return result[i].Value < result[j].Value
+	})
+
+	fmt.Println(result)
+
+	// Output:
+	// [{a 1} {b 2} {c 3}]
+}
+
+func ExampleFromEntries() {
+
+	result := FromEntries([]Entry[string, int]{
+		{Key: "a", Value: 1},
+		{Key: "b", Value: 2},
+		{Key: "c", Value: 3},
+	})
+
+	fmt.Println(result)
+
+	// Output:
+	// map[a:1 b:2 c:3]
+}
+
+func ExampleTransform() {
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+	}
+
+	result := Transform(m, func(k string, v int) (string, string) {
+		return k, strconv.Itoa(v)
+	})
+
+	fmt.Println(result)
+
+	// Output:
+	// map[a:1 b:2 c:3]
+}
+
+func ExampleMapKeys() {
+	m := map[int]string{
+		1: "a",
+		2: "b",
+		3: "c",
+	}
+
+	result := MapKeys(m, func(k int, _ string) string {
+		return strconv.Itoa(k)
+	})
+
+	fmt.Println(result)
+
+	// Output:
+	// map[1:a 2:b 3:c]
+}
+
+func ExampleMapValues() {
+	m := map[int]string{
+		1: "a",
+		2: "b",
+		3: "c",
+	}
+
+	result := MapValues(m, func(k int, v string) string {
+		return v + strconv.Itoa(k)
+	})
+
+	fmt.Println(result)
+
+	// Output:
+	// map[1:a1 2:b2 3:c3]
+}
+
+func ExampleOmitBy() {
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+		"d": 4,
+		"e": 5,
+	}
+	isEven := func(_ string, value int) bool {
+		return value%2 == 0
+	}
+
+	result := OmitBy(m, isEven)
+
+	fmt.Println(result)
+
+	// Output:
+	// map[a:1 c:3 e:5]
+}
+
+func ExampleOmitByKeys() {
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+		"d": 4,
+		"e": 5,
+	}
+
+	result := OmitByKeys(m, []string{"a", "b"})
+
+	fmt.Println(result)
+
+	// Output:
+	// map[c:3 d:4 e:5]
+}
+
+func ExampleOmitByValues() {
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+		"d": 4,
+		"e": 5,
+	}
+
+	result := OmitByValues(m, []int{4, 5})
+
+	fmt.Println(result)
+
+	// Output:
+	// map[a:1 b:2 c:3]
+}
--- a/maputil/map_test.go
+++ b/maputil/map_test.go
@@ -2,6 +2,7 @@ package maputil

 import (
 	"sort"
+	"strconv"
 	"testing"

 	"github.com/duke-git/lancet/v2/internal"
@@ -41,6 +42,51 @@ func TestValues(t *testing.T) {
 	assert.Equal([]string{"a", "a", "b", "c", "d"}, values)
 }

+func TestKeysBy(t *testing.T) {
+	assert := internal.NewAssert(t, "TestKeysBy")
+
+	m := map[int]string{
+		1: "a",
+		2: "a",
+		3: "b",
+	}
+
+	keys := KeysBy(m, func(n int) int {
+		return n + 1
+	})
+
+	sort.Ints(keys)
+
+	assert.Equal([]int{2, 3, 4}, keys)
+}
+
+func TestValuesBy(t *testing.T) {
+	assert := internal.NewAssert(t, "TestValuesBy")
+
+	m := map[int]string{
+		1: "a",
+		2: "b",
+		3: "c",
+	}
+
+	values := ValuesBy(m, func(v string) string {
+		switch v {
+		case "a":
+			return "a-1"
+		case "b":
+			return "b-2"
+		case "c":
+			return "c-3"
+		default:
+			return ""
+		}
+	})
+
+	sort.Strings(values)
+
+	assert.Equal([]string{"a-1", "b-2", "c-3"}, values)
+}
+
 func TestMerge(t *testing.T) {
 	assert := internal.NewAssert(t, "TestMerge")

@@ -104,6 +150,107 @@ func TestFilter(t *testing.T) {
 	}, acturl)
 }

+func TestFilterByKeys(t *testing.T) {
+	assert := internal.NewAssert(t, "TestFilterByKeys")
+
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+		"d": 4,
+		"e": 5,
+	}
+
+	acturl := FilterByKeys(m, []string{"a", "b"})
+
+	assert.Equal(map[string]int{
+		"a": 1,
+		"b": 2,
+	}, acturl)
+}
+
+func TestFilterByValues(t *testing.T) {
+	assert := internal.NewAssert(t, "TestFilterByValues")
+
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+		"d": 4,
+		"e": 5,
+	}
+
+	acturl := FilterByValues(m, []int{3, 4})
+
+	assert.Equal(map[string]int{
+		"c": 3,
+		"d": 4,
+	}, acturl)
+}
+
+func TestOmitBy(t *testing.T) {
+	assert := internal.NewAssert(t, "TestOmitBy")
+
+	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 := OmitBy(m, isEven)
+
+	assert.Equal(map[string]int{
+		"a": 1,
+		"c": 3,
+		"e": 5,
+	}, acturl)
+}
+
+func TestOmitByKeys(t *testing.T) {
+	assert := internal.NewAssert(t, "TestOmitByKeys")
+
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+		"d": 4,
+		"e": 5,
+	}
+
+	acturl := OmitByKeys(m, []string{"a", "b"})
+
+	assert.Equal(map[string]int{
+		"c": 3,
+		"d": 4,
+		"e": 5,
+	}, acturl)
+}
+
+func TestOmitByValues(t *testing.T) {
+	assert := internal.NewAssert(t, "TestOmitByValues")
+
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+		"d": 4,
+		"e": 5,
+	}
+
+	acturl := OmitByValues(m, []int{4, 5})
+
+	assert.Equal(map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+	}, acturl)
+}
+
 func TestIntersect(t *testing.T) {
 	assert := internal.NewAssert(t, "TestIntersect")

@@ -170,3 +317,104 @@ func TestIsDisjoint(t *testing.T) {

 	assert.Equal(false, IsDisjoint(m1, m3))
 }
+
+func TestEntries(t *testing.T) {
+	assert := internal.NewAssert(t, "TestEntries")
+
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+	}
+
+	result := Entries(m)
+
+	sort.Slice(result, func(i, j int) bool {
+		return result[i].Value < result[j].Value
+	})
+
+	expected := []Entry[string, int]{{Key: "a", Value: 1}, {Key: "b", Value: 2}, {Key: "c", Value: 3}}
+
+	assert.Equal(expected, result)
+}
+
+func TestFromEntries(t *testing.T) {
+	assert := internal.NewAssert(t, "TestFromEntries")
+
+	result := FromEntries([]Entry[string, int]{
+		{Key: "a", Value: 1},
+		{Key: "b", Value: 2},
+		{Key: "c", Value: 3},
+	})
+
+	assert.Equal(3, len(result))
+	assert.Equal(1, result["a"])
+	assert.Equal(2, result["b"])
+	assert.Equal(3, result["c"])
+}
+
+func TestTransform(t *testing.T) {
+	assert := internal.NewAssert(t, "TestTransform")
+
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+	}
+
+	result := Transform(m, func(k string, v int) (string, string) {
+		return k, strconv.Itoa(v)
+	})
+
+	expected := map[string]string{
+		"a": "1",
+		"b": "2",
+		"c": "3",
+	}
+
+	assert.Equal(expected, result)
+}
+
+func TestMapKeys(t *testing.T) {
+	assert := internal.NewAssert(t, "TestMapKeys")
+
+	m := map[int]string{
+		1: "a",
+		2: "b",
+		3: "c",
+	}
+
+	result := MapKeys(m, func(k int, _ string) string {
+		return strconv.Itoa(k)
+	})
+
+	expected := map[string]string{
+		"1": "a",
+		"2": "b",
+		"3": "c",
+	}
+
+	assert.Equal(expected, result)
+}
+
+func TestMapValues(t *testing.T) {
+	assert := internal.NewAssert(t, "TestMapKeys")
+
+	m := map[int]string{
+		1: "a",
+		2: "b",
+		3: "c",
+	}
+
+	result := MapValues(m, func(k int, v string) string {
+		return v + strconv.Itoa(k)
+	})
+
+	expected := map[int]string{
+		1: "a1",
+		2: "b2",
+		3: "c3",
+	}
+
+	assert.Equal(expected, result)
+}
--- a/random/random.go
+++ b/random/random.go
@@ -19,6 +19,10 @@ const (
 	Letters       = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
 )

+func init() {
+	rand.Seed(time.Now().UnixNano())
+}
+
 // RandInt generate random int between min and max, maybe min,  not be max.
 // Play: https://go.dev/play/p/pXyyAAI5YxD
 func RandInt(min, max int) int {
@@ -28,9 +32,12 @@ func RandInt(min, max int) int {
 	if max < min {
 		min, max = max, min
 	}
-	r := rand.New(rand.NewSource(time.Now().UnixNano()))

-	return r.Intn(max-min) + min
+	// fix: https://github.com/duke-git/lancet/issues/75
+	// r := rand.New(rand.NewSource(time.Now().UnixNano()))
+	// return r.Intn(max-min) + min
+
+	return rand.Intn(max-min) + min
 }

 // RandBytes generate random byte slice.
@@ -81,10 +88,12 @@ func RandNumeralOrLetter(length int) string {
 // random generate a random string based on given string range.
 func random(s string, length int) string {
 	b := make([]byte, length)
-	r := rand.New(rand.NewSource(time.Now().UnixNano()))
+
+	// fix: https://github.com/duke-git/lancet/issues/75
+	// r := rand.New(rand.NewSource(time.Now().UnixNano()))

 	for i := range b {
-		b[i] = s[r.Int63()%int64(len(s))]
+		b[i] = s[rand.Int63()%int64(len(s))]
 	}

 	return string(b)
--- a/slice/slice.go
+++ b/slice/slice.go
@@ -22,7 +22,7 @@ var (
 )

 // Contain check if the target value is in the slice or not.
-// Play: https://go.dev/play/p/_454yEHcNjf
+// Play: todo
 func Contain[T comparable](slice []T, target T) bool {
 	for _, item := range slice {
 		if item == target {
@@ -33,6 +33,17 @@ func Contain[T comparable](slice []T, target T) bool {
 	return false
 }

+// ContainBy returns true if predicate function return true.
+func ContainBy[T any](slice []T, predicate func(item T) bool) bool {
+	for _, item := range slice {
+		if predicate(item) {
+			return true
+		}
+	}
+
+	return false
+}
+
 // ContainSubSlice check if the slice contain a given subslice or not.
 // Play: https://go.dev/play/p/bcuQ3UT6Sev
 func ContainSubSlice[T comparable](slice, subSlice []T) bool {
@@ -421,6 +432,35 @@ func Map[T any, U any](slice []T, iteratee func(index int, item T) U) []U {
 	return result
 }

+// FilterMap returns a slice which apply both filtering and mapping to the given slice.
+// iteratee callback function should returntwo values:
+// 1, mapping result.
+// 2, whether the result element should be included or not
+// Play: todo
+func FilterMap[T any, U any](slice []T, iteratee func(index int, item T) (U, bool)) []U {
+	result := []U{}
+
+	for i, v := range slice {
+		if a, ok := iteratee(i, v); ok {
+			result = append(result, a)
+		}
+	}
+
+	return result
+}
+
+// FlatMap manipulates a slice and transforms and flattens it to a slice of another type.
+// Play: todo
+func FlatMap[T any, U any](slice []T, iteratee func(index int, item T) []U) []U {
+	result := make([]U, 0, len(slice))
+
+	for i, v := range slice {
+		result = append(result, iteratee(i, v)...)
+	}
+
+	return result
+}
+
 // Reduce creates an slice of values by running each element of slice thru iteratee function.
 // Play: https://go.dev/play/p/_RfXJJWIsIm
 func Reduce[T any](slice []T, iteratee func(index int, item1, item2 T) T, initial T) T {
@@ -559,7 +599,7 @@ func DeleteAt[T any](slice []T, start int, end ...int) []T {
 }

 // Drop drop n elements from the start of a slice.
-// Play: https://go.dev/play/p/pJ-d6MUWcvK
+// Play: https://go.dev/play/p/jnPO2yQsT8H
 func Drop[T any](slice []T, n int) []T {
 	size := len(slice)

@@ -577,7 +617,7 @@ func Drop[T any](slice []T, n int) []T {
 }

 // DropRight drop n elements from the end of a slice.
-// Play: todo
+// Play: https://go.dev/play/p/8bcXvywZezG
 func DropRight[T any](slice []T, n int) []T {
 	size := len(slice)

@@ -595,7 +635,7 @@ func DropRight[T any](slice []T, n int) []T {
 }

 // DropWhile drop n elements from the start of a slice while predicate function returns true.
-// Play: todo
+// Play: https://go.dev/play/p/4rt252UV_qs
 func DropWhile[T any](slice []T, predicate func(item T) bool) []T {
 	i := 0

@@ -611,7 +651,7 @@ func DropWhile[T any](slice []T, predicate func(item T) bool) []T {
 }

 // DropRightWhile drop n elements from the end of a slice while predicate function returns true.
-// Play: todo
+// Play: https://go.dev/play/p/6wyK3zMY56e
 func DropRightWhile[T any](slice []T, predicate func(item T) bool) []T {
 	i := len(slice) - 1

@@ -831,7 +871,7 @@ func Shuffle[T any](slice []T) []T {
 }

 // IsAscending checks if a slice is ascending order.
-// Play: todo
+// Play: https://go.dev/play/p/9CtsFjet4SH
 func IsAscending[T constraints.Ordered](slice []T) bool {
 	for i := 1; i < len(slice); i++ {
 		if slice[i-1] > slice[i] {
@@ -843,7 +883,7 @@ func IsAscending[T constraints.Ordered](slice []T) bool {
 }

 // IsDescending checks if a slice is descending order.
-// Play: todo
+// Play: https://go.dev/play/p/U_LljFXma14
 func IsDescending[T constraints.Ordered](slice []T) bool {
 	for i := 1; i < len(slice); i++ {
 		if slice[i-1] < slice[i] {
@@ -855,13 +895,13 @@ func IsDescending[T constraints.Ordered](slice []T) bool {
 }

 // IsSorted checks if a slice is sorted(ascending or descending).
-// Play: todo
+// Play: https://go.dev/play/p/nCE8wPLwSA-
 func IsSorted[T constraints.Ordered](slice []T) bool {
 	return IsAscending(slice) || IsDescending(slice)
 }

 // IsSortedByKey checks if a slice is sorted by iteratee function.
-// Play: todo
+// Play: https://go.dev/play/p/tUoGB7DOHI4
 func IsSortedByKey[T any, K constraints.Ordered](slice []T, iteratee func(item T) K) bool {
 	size := len(slice)

--- a/slice/slice_example_test.go
+++ b/slice/slice_example_test.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"math"
 	"reflect"
+	"strconv"
 )

 func ExampleContain() {
@@ -18,6 +19,32 @@ func ExampleContain() {
 	// false
 }

+func ExampleContainBy() {
+	type foo struct {
+		A string
+		B int
+	}
+
+	array1 := []foo{{A: "1", B: 1}, {A: "2", B: 2}}
+	result1 := ContainBy(array1, func(f foo) bool { return f.A == "1" && f.B == 1 })
+	result2 := ContainBy(array1, func(f foo) bool { return f.A == "2" && f.B == 1 })
+
+	array2 := []string{"a", "b", "c"}
+	result3 := ContainBy(array2, func(t string) bool { return t == "a" })
+	result4 := 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
+}
+
 func ExampleContainSubSlice() {
 	result1 := ContainSubSlice([]string{"a", "b", "c"}, []string{"a", "b"})
 	result2 := ContainSubSlice([]string{"a", "b", "c"}, []string{"a", "d"})
@@ -367,6 +394,38 @@ func ExampleMap() {
 	// [2 3 4]
 }

+func ExampleFilterMap() {
+	nums := []int{1, 2, 3, 4, 5}
+
+	getEvenNumStr := func(i, num int) (string, bool) {
+		if num%2 == 0 {
+			return strconv.FormatInt(int64(num), 10), true
+		}
+		return "", false
+	}
+
+	result := FilterMap(nums, getEvenNumStr)
+
+	fmt.Printf("%#v", result)
+
+	// Output:
+	// []string{"2", "4"}
+}
+
+func ExampleFlatMap() {
+	nums := []int{1, 2, 3, 4}
+
+	result := 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"}
+}
+
 func ExampleReduce() {
 	nums := []int{1, 2, 3}

--- a/slice/slice_test.go
+++ b/slice/slice_test.go
@@ -3,6 +3,7 @@ package slice
 import (
 	"fmt"
 	"math"
+	"strconv"
 	"testing"

 	"github.com/duke-git/lancet/v2/internal"
@@ -19,6 +20,28 @@ func TestContain(t *testing.T) {
 	assert.Equal(true, Contain([]int{1, 2, 3}, 1))
 }

+func TestContainBy(t *testing.T) {
+	assert := internal.NewAssert(t, "TestContainBy")
+
+	type foo struct {
+		A string
+		B int
+	}
+
+	array1 := []foo{{A: "1", B: 1}, {A: "2", B: 2}}
+	result1 := ContainBy(array1, func(f foo) bool { return f.A == "1" && f.B == 1 })
+	result2 := ContainBy(array1, func(f foo) bool { return f.A == "2" && f.B == 1 })
+
+	array2 := []string{"a", "b", "c"}
+	result3 := ContainBy(array2, func(t string) bool { return t == "a" })
+	result4 := ContainBy(array2, func(t string) bool { return t == "d" })
+
+	assert.Equal(true, result1)
+	assert.Equal(false, result2)
+	assert.Equal(true, result3)
+	assert.Equal(false, result4)
+}
+
 func TestContainSubSlice(t *testing.T) {
 	assert := internal.NewAssert(t, "TestContainSubSlice")
 	assert.Equal(true, ContainSubSlice([]string{"a", "a", "b", "c"}, []string{"a", "a"}))
@@ -315,6 +338,36 @@ func TestMap(t *testing.T) {
 	assert.Equal(studentsOfAdd10Aage, Map(students, mapFunc))
 }

+func TestFilterMap(t *testing.T) {
+	assert := internal.NewAssert(t, "TestFilterMap")
+
+	nums := []int{1, 2, 3, 4, 5}
+
+	getEvenNumStr := func(i, num int) (string, bool) {
+		if num%2 == 0 {
+			return strconv.FormatInt(int64(num), 10), true
+		}
+		return "", false
+	}
+
+	result := FilterMap(nums, getEvenNumStr)
+
+	assert.Equal([]string{"2", "4"}, result)
+}
+
+func TestFlatMap(t *testing.T) {
+	assert := internal.NewAssert(t, "TestFlatMap")
+
+	nums := []int{1, 2, 3, 4}
+
+	result := FlatMap(nums, func(i int, num int) []string {
+		s := "hi-" + strconv.FormatInt(int64(num), 10)
+		return []string{s}
+	})
+
+	assert.Equal([]string{"hi-1", "hi-2", "hi-3", "hi-4"}, result)
+}
+
 func TestReduce(t *testing.T) {
 	cases := [][]int{
 		{},
--- a/strutil/string.go
+++ b/strutil/string.go
@@ -67,44 +67,25 @@ func LowerFirst(s string) string {
 	return string(r) + s[size:]
 }

-// PadEnd pads string on the right side if it's shorter than size.
+// PadStart pads string on the left and right side if it's shorter than size.
 // Padding characters are truncated if they exceed size.
-// Play: https://go.dev/play/p/9xP8rN0vz--
-func PadEnd(source string, size int, padStr string) string {
-	len1 := len(source)
-	len2 := len(padStr)
-
-	if len1 >= size {
-		return source
-	}
-
-	fill := ""
-	if len2 >= size-len1 {
-		fill = padStr[0 : size-len1]
-	} else {
-		fill = strings.Repeat(padStr, size-len1)
-	}
-	return source + fill[0:size-len1]
+// Play: todo
+func Pad(source string, size int, padStr string) string {
+	return padAtPosition(source, size, padStr, 0)
 }

 // PadStart pads string on the left side if it's shorter than size.
 // Padding characters are truncated if they exceed size.
 // Play: https://go.dev/play/p/xpTfzArDfvT
 func PadStart(source string, size int, padStr string) string {
-	len1 := len(source)
-	len2 := len(padStr)
+	return padAtPosition(source, size, padStr, 1)
+}

-	if len1 >= size {
-		return source
-	}
-
-	fill := ""
-	if len2 >= size-len1 {
-		fill = padStr[0 : size-len1]
-	} else {
-		fill = strings.Repeat(padStr, size-len1)
-	}
-	return fill[0:size-len1] + source
+// PadEnd pads string on the right side if it's shorter than size.
+// Padding characters are truncated if they exceed size.
+// Play: https://go.dev/play/p/9xP8rN0vz--
+func PadEnd(source string, size int, padStr string) string {
+	return padAtPosition(source, size, padStr, 2)
 }

 // KebabCase coverts string to kebab-case, non letters and numbers will be ignored.
@@ -306,3 +287,76 @@ func Substring(s string, offset int, length uint) string {

 	return strings.Replace(str, "\x00", "", -1)
 }
+
+// SplitWords splits a string into words, word only contains alphabetic characters.
+// Play: todo
+func SplitWords(s string) []string {
+	var word string
+	var words []string
+	var r rune
+	var size, pos int
+
+	isWord := false
+
+	for len(s) > 0 {
+		r, size = utf8.DecodeRuneInString(s)
+
+		switch {
+		case isLetter(r):
+			if !isWord {
+				isWord = true
+				word = s
+				pos = 0
+			}
+
+		case isWord && (r == '\'' || r == '-'):
+			// is word
+
+		default:
+			if isWord {
+				isWord = false
+				words = append(words, word[:pos])
+			}
+		}
+
+		pos += size
+		s = s[size:]
+	}
+
+	if isWord {
+		words = append(words, word[:pos])
+	}
+
+	return words
+}
+
+// WordCount return the number of meaningful word, word only contains alphabetic characters.
+// Play: todo
+func WordCount(s string) int {
+	var r rune
+	var size, count int
+
+	isWord := false
+
+	for len(s) > 0 {
+		r, size = utf8.DecodeRuneInString(s)
+
+		switch {
+		case isLetter(r):
+			if !isWord {
+				isWord = true
+				count++
+			}
+
+		case isWord && (r == '\'' || r == '-'):
+			// is word
+
+		default:
+			isWord = false
+		}
+
+		s = s[size:]
+	}
+
+	return count
+}
--- a/strutil/string_example_test.go
+++ b/strutil/string_example_test.go
@@ -186,6 +186,33 @@ func ExampleUpperFirst() {
 	// Bar大
 }

+func ExamplePad() {
+	result1 := Pad("foo", 1, "bar")
+	result2 := Pad("foo", 2, "bar")
+	result3 := Pad("foo", 3, "bar")
+	result4 := Pad("foo", 4, "bar")
+	result5 := Pad("foo", 5, "bar")
+	result6 := Pad("foo", 6, "bar")
+	result7 := Pad("foo", 7, "bar")
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+	fmt.Println(result3)
+	fmt.Println(result4)
+	fmt.Println(result5)
+	fmt.Println(result6)
+	fmt.Println(result7)
+
+	// Output:
+	// foo
+	// foo
+	// foo
+	// foob
+	// bfoob
+	// bfooba
+	// bafooba
+}
+
 func ExamplePadEnd() {
 	result1 := PadEnd("foo", 1, "bar")
 	result2 := PadEnd("foo", 2, "bar")
@@ -361,3 +388,53 @@ func ExampleSubstring() {
 	// de
 	// 你好
 }
+
+func ExampleSplitWords() {
+
+	result1 := SplitWords("a word")
+	result2 := SplitWords("I'am a programmer")
+	result3 := SplitWords("Bonjour, je suis programmeur")
+	result4 := SplitWords("a -b-c' 'd'e")
+	result5 := SplitWords("你好，我是一名码农")
+	result6 := SplitWords("こんにちは，私はプログラマーです")
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+	fmt.Println(result3)
+	fmt.Println(result4)
+	fmt.Println(result5)
+	fmt.Println(result6)
+
+	// Output:
+	// [a word]
+	// [I'am a programmer]
+	// [Bonjour je suis programmeur]
+	// [a b-c' d'e]
+	// []
+	// []
+}
+
+func ExampleWordCount() {
+
+	result1 := WordCount("a word")
+	result2 := WordCount("I'am a programmer")
+	result3 := WordCount("Bonjour, je suis programmeur")
+	result4 := WordCount("a -b-c' 'd'e")
+	result5 := WordCount("你好，我是一名码农")
+	result6 := WordCount("こんにちは，私はプログラマーです")
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+	fmt.Println(result3)
+	fmt.Println(result4)
+	fmt.Println(result5)
+	fmt.Println(result6)
+
+	// Output:
+	// 2
+	// 3
+	// 4
+	// 3
+	// 0
+	// 0
+}
--- a/strutil/string_internal.go
+++ b/strutil/string_internal.go
@@ -98,3 +98,73 @@ func toUpperAll(rs []rune) []rune {
 	}
 	return rs
 }
+
+// padWithPosition pads string
+func padAtPosition(str string, length int, padStr string, position int) string {
+	if len(str) >= length {
+		return str
+	}
+
+	if padStr == "" {
+		padStr = " "
+	}
+
+	length = length - len(str)
+	startPadLen := 0
+	if position == 0 {
+		startPadLen = length / 2
+	} else if position == 1 {
+		startPadLen = length
+	}
+	endPadLen := length - startPadLen
+
+	charLen := len(padStr)
+	leftPad := ""
+	cur := 0
+	for cur < startPadLen {
+		leftPad += string(padStr[cur%charLen])
+		cur++
+	}
+
+	cur = 0
+	rightPad := ""
+	for cur < endPadLen {
+		rightPad += string(padStr[cur%charLen])
+		cur++
+	}
+
+	return leftPad + str + rightPad
+}
+
+// isLetter checks r is a letter but not CJK character.
+func isLetter(r rune) bool {
+	if !unicode.IsLetter(r) {
+		return false
+	}
+
+	switch {
+	// cjk char: /[\u3040-\u30ff\u3400-\u4dbf\u4e00-\u9fff\uf900-\ufaff\uff66-\uff9f]/
+
+	// hiragana and katakana (Japanese only)
+	case r >= '\u3034' && r < '\u30ff':
+		return false
+
+	// CJK unified ideographs extension A (Chinese, Japanese, and Korean)
+	case r >= '\u3400' && r < '\u4dbf':
+		return false
+
+	// CJK unified ideographs (Chinese, Japanese, and Korean)
+	case r >= '\u4e00' && r < '\u9fff':
+		return false
+
+	// CJK compatibility ideographs (Chinese, Japanese, and Korean)
+	case r >= '\uf900' && r < '\ufaff':
+		return false
+
+	// half-width katakana (Japanese only)
+	case r >= '\uff66' && r < '\uff9f':
+		return false
+	}
+
+	return true
+}
--- a/strutil/string_test.go
+++ b/strutil/string_test.go
@@ -168,9 +168,19 @@ func TestLowerFirst(t *testing.T) {
 	}
 }

+func TestPad(t *testing.T) {
+	assert := internal.NewAssert(t, "TestPad")
+
+	assert.Equal("a ", Pad("a", 2, ""))
+	assert.Equal("a", Pad("a", 1, "b"))
+	assert.Equal("ab", Pad("a", 2, "b"))
+	assert.Equal("mabcdm", Pad("abcd", 6, "m"))
+}
+
 func TestPadEnd(t *testing.T) {
 	assert := internal.NewAssert(t, "TestPadEnd")

+	assert.Equal("a ", PadEnd("a", 2, " "))
 	assert.Equal("a", PadEnd("a", 1, "b"))
 	assert.Equal("ab", PadEnd("a", 2, "b"))
 	assert.Equal("abcdmn", PadEnd("abcd", 6, "mno"))
@@ -298,3 +308,37 @@ func TestSubstring(t *testing.T) {
 	assert.Equal("de", Substring("abcde", -2, 3))
 	assert.Equal("你好", Substring("你好，欢迎你", 0, 2))
 }
+
+func TestSplitWords(t *testing.T) {
+	assert := internal.NewAssert(t, "TestSplitWords")
+
+	cases := map[string][]string{
+		"a word":                       {"a", "word"},
+		"I'am a programmer":            {"I'am", "a", "programmer"},
+		"Bonjour, je suis programmeur": {"Bonjour", "je", "suis", "programmeur"},
+		"a -b-c' 'd'e":                 {"a", "b-c'", "d'e"},
+		"你好，我是一名码农":                    nil,
+		"こんにちは，私はプログラマーです": nil,
+	}
+
+	for k, v := range cases {
+		assert.Equal(v, SplitWords(k))
+	}
+}
+
+func TestWordCount(t *testing.T) {
+	assert := internal.NewAssert(t, "TestSplitWords")
+
+	cases := map[string]int{
+		"a word":                       2, //   {"a", "word"},
+		"I'am a programmer":            3, //   {"I'am", "a", "programmer"},
+		"Bonjour, je suis programmeur": 4, // {"Bonjour", "je", "suis", "programmeur"},
+		"a -b-c' 'd'e":                 3, // {"a", "b-c'", "d'e"},
+		"你好，我是一名码农":                    0, // nil,
+		"こんにちは，私はプログラマーです": 0, // nil,
+	}
+
+	for k, v := range cases {
+		assert.Equal(v, WordCount(k))
+	}
+}
Author	SHA1	Message	Date
dudaodong	66efe61834	release v2.1.16	2023-03-01 10:08:53 +08:00
dudaodong	94f7f3e0e5	doc: add new function docs	2023-02-28 15:03:02 +08:00
dudaodong	9d2c9806d1	feat: add ContainBy function	2023-02-24 14:19:10 +08:00
dudaodong	e523d4af6e	doc: add doc for FilterMap and FlatMap	2023-02-24 11:23:02 +08:00
dudaodong	f3801bcd8f	feat: add FlatMap	2023-02-24 11:14:59 +08:00
dudaodong	5767aad303	feat: add FilterMap	2023-02-24 10:55:27 +08:00
dudaodong	f7aaa1ed2a	fix: fix issue #75	2023-02-23 11:43:41 +08:00
dudaodong	ef19a414bc	doc: fix doc error	2023-02-23 10:58:43 +08:00
dudaodong	65704dea06	doc: fix doc error	2023-02-23 10:57:48 +08:00
dudaodong	5eac358bb0	doc: format code in doc file	2023-02-22 17:00:46 +08:00
dudaodong	8e36ef5cef	doc: add doc for new map functions	2023-02-22 16:59:01 +08:00
dudaodong	21b0d2ec0e	doc: add doc for WordCount and SplitWords function	2023-02-22 16:13:41 +08:00
dudaodong	32ca975204	feat: add OmitBy, OmitByKeys, OmitByValues	2023-02-21 14:52:10 +08:00
dudaodong	ec740e442c	feat: add WordCount	2023-02-21 14:27:00 +08:00
dudaodong	ed98ad53ec	feat: add SplitWords	2023-02-21 14:16:36 +08:00
dudaodong	af7b9d2710	doc: add doc for CopyProperties function	2023-02-20 14:10:55 +08:00
dudaodong	f08b368001	fix: update param type of CopyProperties	2023-02-20 14:04:45 +08:00
dudaodong	be8a0558f8	test: add examples for CopyProperties function	2023-02-20 12:00:49 +08:00
dudaodong	46de539e22	feat: add CopyProperties for merge properties between structs	2023-02-20 11:48:30 +08:00
dudaodong	36fb3abe9e	test: add examples for maputil package function	2023-02-19 16:59:21 +08:00
dudaodong	fee8d325b7	doc: add doc for Pad function	2023-02-19 12:58:14 +08:00
dudaodong	8784be1583	feat: add Pad function	2023-02-19 12:37:26 +08:00
dudaodong	84cd68de7f	fix: fix bugs of PadEnd and PadStart	2023-02-19 12:34:39 +08:00
dudaodong	a774c060ce	feat: add MapKeys and MapValues	2023-02-17 15:41:58 +08:00
dudaodong	730f061b95	feat: add Entries FromEntries Transform	2023-02-17 15:24:46 +08:00
dudaodong	2eb08f3404	feat: add FilterByValues function	2023-02-17 11:59:44 +08:00
dudaodong	4c1496b648	feat: add FilterByKeys function	2023-02-17 11:57:09 +08:00
dudaodong	c2ae784f27	feat: add ValuesBy function	2023-02-17 11:48:11 +08:00
dudaodong	e71cecefea	feat: add KeysBy function	2023-02-17 11:40:20 +08:00
dudaodong	572e53aa14	doc: add go playground demo for xerror package	2023-02-16 14:28:50 +08:00
dudaodong	ca9ecb9c8a	update go playground demo	2023-02-16 14:10:24 +08:00