doc: add Gurubase and update Sponsor text

Merge branch 'rc'
doc: add doc for Permutation and Combination function
2026-03-01 00:35:28 +08:00 · 2024-11-19 10:29:41 +08:00 · 2024-11-19 10:26:41 +08:00 · 2024-11-19 10:25:32 +08:00 · 2024-11-19 10:21:30 +08:00 · 2024-11-19 10:12:07 +08:00
15 changed files with 632 additions and 129 deletions
--- a/README.md
+++ b/README.md
@@ -10,6 +10,7 @@
 [![test](https://github.com/duke-git/lancet/actions/workflows/codecov.yml/badge.svg?branch=main&event=push)](https://github.com/duke-git/lancet/actions/workflows/codecov.yml)
 [![codecov](https://codecov.io/gh/duke-git/lancet/branch/main/graph/badge.svg?token=FC48T1F078)](https://codecov.io/gh/duke-git/lancet)
 [![License](https://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/duke-git/lancet/blob/main/LICENSE)
+[![Gurubase](https://img.shields.io/badge/Gurubase-Ask%20Lancet%20Guru-006BFF)](https://gurubase.io/g/lancet)

 </div>

--- a/README_zh-CN.md
+++ b/README_zh-CN.md
@@ -10,6 +10,7 @@
 [![test](https://github.com/duke-git/lancet/actions/workflows/codecov.yml/badge.svg?branch=main&event=push)](https://github.com/duke-git/lancet/actions/workflows/codecov.yml)
 [![codecov](https://codecov.io/gh/duke-git/lancet/branch/main/graph/badge.svg?token=FC48T1F078)](https://codecov.io/gh/duke-git/lancet)
 [![License](https://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/duke-git/lancet/blob/main/LICENSE)
+[![Gurubase](https://img.shields.io/badge/Gurubase-Ask%20Lancet%20Guru-006BFF)](https://gurubase.io/g/lancet)

 </div>

--- a/algorithm/lrucache_test.go
+++ b/algorithm/lrucache_test.go
@@ -8,7 +8,7 @@ import (

 func TestLRUCache(t *testing.T) {
 	t.Parallel()
-	asssert := internal.NewAssert(t, "TestLRUCache")
+	assert := internal.NewAssert(t, "TestLRUCache")

 	cache := NewLRUCache[int, int](3)

@@ -16,19 +16,19 @@ func TestLRUCache(t *testing.T) {
 	cache.Put(2, 2)
 	cache.Put(3, 3)

-	asssert.Equal(3, cache.Len())
+	assert.Equal(3, cache.Len())

 	v, ok := cache.Get(1)
-	asssert.Equal(true, ok)
-	asssert.Equal(1, v)
+	assert.Equal(true, ok)
+	assert.Equal(1, v)

 	v, ok = cache.Get(2)
-	asssert.Equal(true, ok)
-	asssert.Equal(2, v)
+	assert.Equal(true, ok)
+	assert.Equal(2, v)

 	ok = cache.Delete(2)
-	asssert.Equal(true, ok)
+	assert.Equal(true, ok)

 	_, ok = cache.Get(2)
-	asssert.Equal(false, ok)
+	assert.Equal(false, ok)
 }
--- a/algorithm/search_test.go
+++ b/algorithm/search_test.go
@@ -8,34 +8,34 @@ import (

 func TestLinearSearch(t *testing.T) {
 	t.Parallel()
-	asssert := internal.NewAssert(t, "TestLinearSearch")
+	assert := internal.NewAssert(t, "TestLinearSearch")

 	numbers := []int{3, 4, 5, 3, 2, 1}
 	equalFunc := func(a, b int) bool {
 		return a == b
 	}

-	asssert.Equal(0, LinearSearch(numbers, 3, equalFunc))
-	asssert.Equal(-1, LinearSearch(numbers, 6, equalFunc))
+	assert.Equal(0, LinearSearch(numbers, 3, equalFunc))
+	assert.Equal(-1, LinearSearch(numbers, 6, equalFunc))
 }

 func TestBinarySearch(t *testing.T) {
 	t.Parallel()
-	asssert := internal.NewAssert(t, "TestBinarySearch")
+	assert := internal.NewAssert(t, "TestBinarySearch")

 	sortedNumbers := []int{1, 2, 3, 4, 5, 6, 7, 8}
 	comparator := &intComparator{}

-	asssert.Equal(4, BinarySearch(sortedNumbers, 5, 0, len(sortedNumbers)-1, comparator))
-	asssert.Equal(-1, BinarySearch(sortedNumbers, 9, 0, len(sortedNumbers)-1, comparator))
+	assert.Equal(4, BinarySearch(sortedNumbers, 5, 0, len(sortedNumbers)-1, comparator))
+	assert.Equal(-1, BinarySearch(sortedNumbers, 9, 0, len(sortedNumbers)-1, comparator))
 }

 func TestBinaryIterativeSearch(t *testing.T) {
-	asssert := internal.NewAssert(t, "TestBinaryIterativeSearch")
+	assert := internal.NewAssert(t, "TestBinaryIterativeSearch")

 	sortedNumbers := []int{1, 2, 3, 4, 5, 6, 7, 8}
 	comparator := &intComparator{}

-	asssert.Equal(4, BinaryIterativeSearch(sortedNumbers, 5, 0, len(sortedNumbers)-1, comparator))
-	asssert.Equal(-1, BinaryIterativeSearch(sortedNumbers, 9, 0, len(sortedNumbers)-1, comparator))
+	assert.Equal(4, BinaryIterativeSearch(sortedNumbers, 5, 0, len(sortedNumbers)-1, comparator))
+	assert.Equal(-1, BinaryIterativeSearch(sortedNumbers, 9, 0, len(sortedNumbers)-1, comparator))
 }
--- a/algorithm/sort_test.go
+++ b/algorithm/sort_test.go
@@ -47,7 +47,7 @@ func (c *intComparator) Compare(v1 any, v2 any) int {

 func TestBubbleSortForStructSlice(t *testing.T) {
 	t.Parallel()
-	asssert := internal.NewAssert(t, "TestBubbleSortForStructSlice")
+	assert := internal.NewAssert(t, "TestBubbleSortForStructSlice")

 	peoples := []people{
 		{Name: "a", Age: 20},
@@ -62,23 +62,23 @@ func TestBubbleSortForStructSlice(t *testing.T) {
 	expected := "[{d 8} {b 10} {c 17} {a 20} {e 28}]"
 	actual := fmt.Sprintf("%v", peoples)

-	asssert.Equal(expected, actual)
+	assert.Equal(expected, actual)
 }

 func TestBubbleSortForIntSlice(t *testing.T) {
 	t.Parallel()
-	asssert := internal.NewAssert(t, "TestBubbleSortForIntSlice")
+	assert := internal.NewAssert(t, "TestBubbleSortForIntSlice")

 	numbers := []int{2, 1, 5, 3, 6, 4}
 	comparator := &intComparator{}
 	BubbleSort(numbers, comparator)

-	asssert.Equal([]int{1, 2, 3, 4, 5, 6}, numbers)
+	assert.Equal([]int{1, 2, 3, 4, 5, 6}, numbers)
 }

 func TestInsertionSort(t *testing.T) {
 	t.Parallel()
-	asssert := internal.NewAssert(t, "TestInsertionSort")
+	assert := internal.NewAssert(t, "TestInsertionSort")

 	peoples := []people{
 		{Name: "a", Age: 20},
@@ -93,12 +93,12 @@ func TestInsertionSort(t *testing.T) {
 	expected := "[{d 8} {b 10} {c 17} {a 20} {e 28}]"
 	actual := fmt.Sprintf("%v", peoples)

-	asssert.Equal(expected, actual)
+	assert.Equal(expected, actual)
 }

 func TestSelectionSort(t *testing.T) {
 	t.Parallel()
-	asssert := internal.NewAssert(t, "TestSelectionSort")
+	assert := internal.NewAssert(t, "TestSelectionSort")

 	peoples := []people{
 		{Name: "a", Age: 20},
@@ -113,12 +113,12 @@ func TestSelectionSort(t *testing.T) {
 	expected := "[{d 8} {b 10} {c 17} {a 20} {e 28}]"
 	actual := fmt.Sprintf("%v", peoples)

-	asssert.Equal(expected, actual)
+	assert.Equal(expected, actual)
 }

 func TestShellSort(t *testing.T) {
 	t.Parallel()
-	asssert := internal.NewAssert(t, "TestShellSort")
+	assert := internal.NewAssert(t, "TestShellSort")

 	peoples := []people{
 		{Name: "a", Age: 20},
@@ -133,12 +133,12 @@ func TestShellSort(t *testing.T) {
 	expected := "[{d 8} {b 10} {c 17} {a 20} {e 28}]"
 	actual := fmt.Sprintf("%v", peoples)

-	asssert.Equal(expected, actual)
+	assert.Equal(expected, actual)
 }

 func TestQuickSort(t *testing.T) {
 	t.Parallel()
-	asssert := internal.NewAssert(t, "TestQuickSort")
+	assert := internal.NewAssert(t, "TestQuickSort")

 	peoples := []people{
 		{Name: "a", Age: 20},
@@ -153,12 +153,12 @@ func TestQuickSort(t *testing.T) {
 	expected := "[{d 8} {b 10} {c 17} {a 20} {e 28}]"
 	actual := fmt.Sprintf("%v", peoples)

-	asssert.Equal(expected, actual)
+	assert.Equal(expected, actual)
 }

 func TestHeapSort(t *testing.T) {
 	t.Parallel()
-	asssert := internal.NewAssert(t, "TestHeapSort")
+	assert := internal.NewAssert(t, "TestHeapSort")

 	peoples := []people{
 		{Name: "a", Age: 20},
@@ -173,12 +173,12 @@ func TestHeapSort(t *testing.T) {
 	expected := "[{d 8} {b 10} {c 17} {a 20} {e 28}]"
 	actual := fmt.Sprintf("%v", peoples)

-	asssert.Equal(expected, actual)
+	assert.Equal(expected, actual)
 }

 func TestMergeSort(t *testing.T) {
 	t.Parallel()
-	asssert := internal.NewAssert(t, "TestMergeSort")
+	assert := internal.NewAssert(t, "TestMergeSort")

 	peoples := []people{
 		{Name: "a", Age: 20},
@@ -193,12 +193,12 @@ func TestMergeSort(t *testing.T) {
 	expected := "[{d 8} {b 10} {c 17} {a 20} {e 28}]"
 	actual := fmt.Sprintf("%v", peoples)

-	asssert.Equal(expected, actual)
+	assert.Equal(expected, actual)
 }

 func TestCountSort(t *testing.T) {
 	t.Parallel()
-	asssert := internal.NewAssert(t, "TestCountSort")
+	assert := internal.NewAssert(t, "TestCountSort")

 	peoples := []people{
 		{Name: "a", Age: 20},
@@ -213,5 +213,5 @@ func TestCountSort(t *testing.T) {
 	expected := "[{d 8} {b 10} {c 17} {a 20} {e 28}]"
 	actual := fmt.Sprintf("%v", sortedPeopleByAge)

-	asssert.Equal(expected, actual)
+	assert.Equal(expected, actual)
 }
--- a/cryptor/rsa_private_example.pem
+++ b/cryptor/rsa_private_example.pem
@@ -1,51 +1,51 @@
 -----BEGIN rsa private key-----
-MIIJKQIBAAKCAgEA3bRSY5GD7uJB3jvwqa9ZZFpN3uLIGbbPA+yiyf6tJZp3K3rm
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-haxULx+MIjQn3XXowYvr4fX7N052t4IC95tAanPEEwZRQJOVMtibAxwI/ofUOCpT
-PtuK3AoErDxS18JPgjQ34yY4Jsch0de53+SjTk+bJpLUlnY4brm+A23FhwTlE5nj
-rKA+Texrg52KJ8aPhLuVQBcZP1SJsxv2PZruuD+0xfLDRrZ7BOTpun+1FBhdlxBe
-fIfBQbBBfy7STw+ignTaO+IRIHhcqKZ+12Na+4GAusmpSiB3LATy82h0nB0PX3hS
-OLYmFI61px4l/yM50E4brF1NFtd/BpoozZajgxjJaznuZXFQ1YSG0JjCeszqdzU+
-6dexGTr+4Lr87NfLekmUX1nZYy/E5lST65lGlI4hX1nR5+nVN9ALRYByNz6oJd0I
-fF4dhoNlGPc1VksskeY8rPZwXITbSifAN7zvEiwKreFV3t0BLKsvWRu9GdpWy+d2
-AmelXkNm+QaH2mPM17euMoNZVyzizrZaJkh/aHO/UgY1/y7sXFl4akC9hk9ILONC
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+cWDmHq0AUVyx6E4ju4ZVZToBzyLmnB6JBPpJjlUktrTtuOuPwO2ozVU4/dnCpi8L
+74vJA9Bo4jnlmV8qDk6NmYaIeIGhJsaPAoIBADVCmkCaMkySTHoC2icsinuQ2zQK
+IkpuE7QxhD2r1WWSmsnKaP1WmYyfrcQefzBd4UN+0Amgq74qG9qfxXEzss1mAu+N
+umO3suQ5BpFN9iVbmdAWC7SqAClPEZFHBMOd9B6nyBnv0Xp3Pclpk/ThPUTm2sxd
+YvFEa8itw9NM0P2lXAYMM+ksFDThcf+sK+510+Du6aj/CZ5YhutRN0tbwNzN7ewT
+QBGpCuEJ9XUjGxmE5YmKSDMPgBLOnjb4tywWwlYsndOnMpN6vpi+OZaZnZBqTiqF
+9IZyUBoN+yHrFVF+O6ZZiSzSz8xSVhwoLTrBX3D2qrP02jg4sG1coiEX6iE=
 -----END rsa private key-----
--- a/cryptor/rsa_public_example.pem
+++ b/cryptor/rsa_public_example.pem
@@ -1,14 +1,14 @@
 -----BEGIN rsa public key-----
-MIICIjANBgkqhkiG9w0BAQEFAAOCAg8AMIICCgKCAgEA3bRSY5GD7uJB3jvwqa9Z
-ZFpN3uLIGbbPA+yiyf6tJZp3K3rmkVFfEcWqtK1EfHvd9G4rqLYJ9ZcohDZgD/Ww
-mqJtaaWh2/7feMPaitp50bYVilpPhaxULx+MIjQn3XXowYvr4fX7N052t4IC95tA
-anPEEwZRQJOVMtibAxwI/ofUOCpTPtuK3AoErDxS18JPgjQ34yY4Jsch0de53+Sj
-Tk+bJpLUlnY4brm+A23FhwTlE5njrKA+Texrg52KJ8aPhLuVQBcZP1SJsxv2PZru
-uD+0xfLDRrZ7BOTpun+1FBhdlxBefIfBQbBBfy7STw+ignTaO+IRIHhcqKZ+12Na
-+4GAusmpSiB3LATy82h0nB0PX3hSOLYmFI61px4l/yM50E4brF1NFtd/BpoozZaj
-gxjJaznuZXFQ1YSG0JjCeszqdzU+6dexGTr+4Lr87NfLekmUX1nZYy/E5lST65lG
-lI4hX1nR5+nVN9ALRYByNz6oJd0IfF4dhoNlGPc1VksskeY8rPZwXITbSifAN7zv
-EiwKreFV3t0BLKsvWRu9GdpWy+d2AmelXkNm+QaH2mPM17euMoNZVyzizrZaJkh/
-aHO/UgY1/y7sXFl4akC9hk9ILONCUn6FVI4BXMXb5kZgwDk5tWE5A159LtC579yG
-cnxyc9Y9NNFOGrqFqPiu6QUCAwEAAQ==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 -----END rsa public key-----
--- a/docs/api/packages/mathutil.md
+++ b/docs/api/packages/mathutil.md
@@ -33,7 +33,7 @@ import (
 -   [Percent](#Percent)
 -   [RoundToFloat](#RoundToFloat)
 -   [RoundToString](#RoundToString)
-   [TruncRound](#TruncRound)
+-   [T运行cRound](#T运行cRound)
 -   [CeilToFloat](#CeilToFloat)
 -   [CeilToString](#CeilToString)
 -   [FloorToFloat](#FloorToFloat)
@@ -52,6 +52,10 @@ import (
 -   [Sum](#Sum)
 -   [Abs](#Abs)
 -   [Div](#Div)
+-   [Variance](#Variance)
+-   [StdDev](#StdDev)
+-   [Permutation](#Permutation)
+-   [Combination](#Combination)

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

@@ -64,7 +68,7 @@ import (
 <b>函数签名:</b>

 ```go
-func Average[T constraints.Integer | constraints.Float](numbers ...T) T
+func Average[T constraints.Integer | constraints.Float](numbers ...T) float64
 ```

 <b>示例:<span style="float:right;display:inline-block;">[运行](https://go.dev/play/p/HFd70x4DrMj)</span></b>
@@ -87,7 +91,7 @@ func main() {
    fmt.Println(result2)

    // Output:
-    // 1
+    // 1.5
    // 1.3
 }
 ```
@@ -462,14 +466,14 @@ func main() {
 }
 ```

-### <span id="TruncRound">TruncRound</span>
+### <span id="T运行cRound">T运行cRound</span>

 <p>截短n位小数（不进行四舍五入）</p>

 <b>函数签名:</b>

 ```go
-func TruncRound[T constraints.Float | constraints.Integer](x T, n int) T 
+func T运行cRound[T constraints.Float | constraints.Integer](x T, n int) T 
 ```

 <b>示例:<span style="float:right;display:inline-block;">[运行](https://go.dev/play/p/aumarSHIGzP)</span></b>
@@ -483,9 +487,9 @@ import (
 )

 func main() {
-    result1 := mathutil.TruncRound(0.124, 2)
-    result2 := mathutil.TruncRound(0.125, 2)
-    result3 := mathutil.TruncRound(0.125, 3)
+    result1 := mathutil.T运行cRound(0.124, 2)
+    result2 := mathutil.T运行cRound(0.125, 2)
+    result3 := mathutil.T运行cRound(0.125, 3)

    fmt.Println(result1)
    fmt.Println(result2)
@@ -1045,8 +1049,8 @@ import (

 func main() {
    result1 := mathutil.Log(8, 2)
-    result2 := mathutil.TruncRound(mathutil.Log(5, 2), 2)
-    result3 := mathutil.TruncRound(mathutil.Log(27, 3), 0)
+    result2 := mathutil.T运行cRound(mathutil.Log(5, 2), 2)
+    result3 := mathutil.T运行cRound(mathutil.Log(27, 3), 0)

    fmt.Println(result1)
    fmt.Println(result2)
@@ -1162,4 +1166,136 @@ func main() {
    // 0.5
    // 0
 }
+```
+
+### <span id="Variance">Variance</span>
+
+<p>计算方差。</p>
+
+<b>函数签名:</b>
+
+```go
+func Variance[T constraints.Float | constraints.Integer](numbers []T) float64
+```
+
+<b>示例:<span style="float:right;display:inline-block;">[示例](todo)</span></b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/mathutil"
+)
+
+func main() {
+    result1 := mathutil.Variance([]int{1, 2, 3, 4, 5})
+    result2 := mathutil.Variance([]float64{1.1, 2.2, 3.3, 4.4, 5.5})
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+
+    // Output:
+    // 2
+    // 2.42
+}
+```
+
+### <span id="StdDev">StdDev</span>
+
+<p>计算标准差。</p>
+
+<b>函数签名:</b>
+
+```go
+func StdDev[T constraints.Float | constraints.Integer](numbers []T) float64
+```
+
+<b>示例:<span style="float:right;display:inline-block;">[运行](todo)</span></b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/mathutil"
+)
+
+func main() {
+    result1 := mathutil.T运行cRound(mathutil.StdDev([]int{1, 2, 3, 4, 5}), 2)
+    result2 := mathutil.T运行cRound(mathutil.StdDev([]float64{1.1, 2.2, 3.3, 4.4, 5.5}), 2)
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+
+    // Output:
+    // 1.41
+    // 1.55
+}
+```
+
+### <span id="Permutation">Permutation</span>
+
+<p>计算排列数（P(n, k)）。</p>
+
+<b>函数签名:</b>
+
+```go
+func Permutation(n, k uint) uint
+```
+
+<b>示例:<span style="float:right;display:inline-block;">[运行](todo)</span></b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/mathutil"
+)
+
+func main() {
+    result1 := mathutil.Permutation(5, 3)
+    result2 := mathutil.Permutation(5, 5)
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+
+    // Output:
+    // 60
+    // 120
+}
+```
+
+### <span id="Combination">Combination</span>
+
+<p>计算组合数（C(n, k)）。</p>
+
+<b>函数签名:</b>
+
+```go
+func Combination(n, k uint) uint
+```
+
+<b>示例:<span style="float:right;display:inline-block;">[运行](todo)</span></b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/mathutil"
+)
+
+func main() {
+    result1 := mathutil.Combination(5, 3)
+    result2 := mathutil.Combination(5, 5)
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+
+    // Output:
+    // 10
+    // 1
+}
 ```
--- a/docs/en/api/packages/mathutil.md
+++ b/docs/en/api/packages/mathutil.md
@@ -52,6 +52,10 @@ import (
 -   [Sum](#Sum)
 -   [Abs](#Abs)
 -   [Div](#Div)
+-   [Variance](#Variance)
+-   [StdDev](#StdDev)
+-   [Permutation](#Permutation)
+-   [Combination](#Combination)

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

@@ -64,7 +68,7 @@ import (
 <b>Signature:</b>

 ```go
-func Average[T constraints.Integer | constraints.Float](numbers ...T) T
+func Average[T constraints.Integer | constraints.Float](numbers ...T) float64
 ```

 <b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/Vv7LBwER-pz)</span></b>
@@ -87,7 +91,7 @@ func main() {
    fmt.Println(result2)

    // Output:
-    // 1
+    // 1.5
    // 1.3
 }
 ```
@@ -1161,4 +1165,136 @@ func main() {
    // 0.5
    // 0
 }
+```
+
+### <span id="Variance">Variance</span>
+
+<p>Returns the variance of numbers.</p>
+
+<b>Signature:</b>
+
+```go
+func Variance[T constraints.Float | constraints.Integer](numbers []T) float64
+```
+
+<b>Example:<span style="float:right;display:inline-block;">[Run](todo)</span></b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/mathutil"
+)
+
+func main() {
+    result1 := mathutil.Variance([]int{1, 2, 3, 4, 5})
+    result2 := mathutil.Variance([]float64{1.1, 2.2, 3.3, 4.4, 5.5})
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+
+    // Output:
+    // 2
+    // 2.42
+}
+```
+
+### <span id="StdDev">StdDev</span>
+
+<p>Returns the standard deviation of numbers.</p>
+
+<b>Signature:</b>
+
+```go
+func StdDev[T constraints.Float | constraints.Integer](numbers []T) float64
+```
+
+<b>Example:<span style="float:right;display:inline-block;">[Run](todo)</span></b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/mathutil"
+)
+
+func main() {
+    result1 := mathutil.TruncRound(mathutil.StdDev([]int{1, 2, 3, 4, 5}), 2)
+    result2 := mathutil.TruncRound(mathutil.StdDev([]float64{1.1, 2.2, 3.3, 4.4, 5.5}), 2)
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+
+    // Output:
+    // 1.41
+    // 1.55
+}
+```
+
+### <span id="Permutation">Permutation</span>
+
+<p>Calculates P(n, k).</p>
+
+<b>Signature:</b>
+
+```go
+func Permutation(n, k uint) uint
+```
+
+<b>Example:<span style="float:right;display:inline-block;">[Run](todo)</span></b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/mathutil"
+)
+
+func main() {
+    result1 := mathutil.Permutation(5, 3)
+	result2 := mathutil.Permutation(5, 5)
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+
+	// Output:
+	// 60
+	// 120
+}
+```
+
+### <span id="Combination">Combination</span>
+
+<p>Calculates C(n, k).</p>
+
+<b>Signature:</b>
+
+```go
+func Combination(n, k uint) uint
+```
+
+<b>Example:<span style="float:right;display:inline-block;">[Run](todo)</span></b>
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/mathutil"
+)
+
+func main() {
+    result1 := mathutil.Combination(5, 3)
+	result2 := mathutil.Combination(5, 5)
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+
+	// Output:
+	// 10
+	// 1
+}
 ```
--- a/docs/en/sponsor/sponsor.md
+++ b/docs/en/sponsor/sponsor.md
@@ -2,7 +2,7 @@

 ### Sponsor me

-<b>Hello, I am a software developer and have been engaged in development work for 13 years. Love open source software. And be willing to put in the energy for it. I am the creator of project [lancet](https://github.com/duke-git/lancet). Since Lancet was released as open source two years ago, it has been used by more than 1,000 internal and external projects. lancet will always be free for all users. Your support is a powerful encouragement for me to continue my struggle. Thanks! You can use WeChat to scans the following QR code or clicks the following sponsor button to initiate sponsorship.</b>
+<b>Hello, I am a software developer and have been engaged in development work for 15 years. Love open source software. And be willing to put in the energy for it. I am the creator of project [lancet](https://github.com/duke-git/lancet). Since Lancet was released as open source in 2021, it has been used by more than 1700 internal and external projects. lancet will always be free for all users. Your support is a powerful encouragement for me to continue my struggle. Thanks! You can use WeChat to scans the following QR code or clicks the following sponsor button to initiate sponsorship.</b>

 <style>
    .sponsor-ctn {
--- a/docs/sponsor/sponsor.md
+++ b/docs/sponsor/sponsor.md
@@ -1,6 +1,6 @@
 ### 赞助

-<b>您好，我是一名软件开发者，从事开发工作 13 年。热爱软件开源。并愿意为此付出精力。是开源项目[lancet](https://github.com/duke-git/lancet)的作者。Lancet 自两年前开源发布以来，已有超过 1000 个内外部项目使用。lancet 一直会对所有用户免费。您的支持是对我继续奋斗的有力鼓励。谢谢! 微信扫描以下二维码或点击以下赞助按钮发起赞助。 </b>
+<b>您好，我是一名软件开发者，从事开发工作15年。热爱软件开源。并愿意为此付出精力。是开源项目[lancet](https://github.com/duke-git/lancet)的作者。Lancet自2021年前开源发布以来，已有超过1700个内外部项目使用。lancet一直会对所有用户免费。您的支持是对我继续奋斗的有力鼓励。谢谢! 微信扫描以下二维码或点击以下赞助按钮发起赞助。 </b>

 <style>
    .sponsor-ctn {
--- a/mathutil/mathutil.go
+++ b/mathutil/mathutil.go
@@ -44,14 +44,19 @@ func Fibonacci(first, second, n int) int {
 	}
 }

-// Factorial calculate x!.
+// Factorial calculate n!.
 // Play: https://go.dev/play/p/tt6LdOK67Nx
-func Factorial(x uint) uint {
-	var f uint = 1
-	for ; x > 1; x-- {
-		f *= x
+func Factorial(n uint) uint {
+	if n == 0 || n == 1 {
+		return 1
 	}
-	return f
+
+	result := uint(1)
+	for i := uint(2); i <= n; i++ {
+		result *= i
+	}
+
+	return result
 }

 // Percent calculate the percentage of value to total.
@@ -224,14 +229,12 @@ func Sum[T constraints.Integer | constraints.Float](numbers ...T) T {

 // Average return average value of numbers.
 // Play: https://go.dev/play/p/Vv7LBwER-pz
-func Average[T constraints.Integer | constraints.Float](numbers ...T) T {
-	var sum T
-	n := T(len(numbers))
-
-	for _, v := range numbers {
-		sum += v
+func Average[T constraints.Integer | constraints.Float](numbers ...T) float64 {
+	var sum float64
+	for _, num := range numbers {
+		sum += float64(num)
 	}
-	return sum / n
+	return sum / float64(len(numbers))
 }

 // Range creates a slice of numbers from start with specified count, element step is 1.
@@ -395,3 +398,54 @@ func Abs[T constraints.Integer | constraints.Float](x T) T {
 func Div[T constraints.Float | constraints.Integer](x T, y T) float64 {
 	return float64(x) / float64(y)
 }
+
+// Variance returns the variance of numbers.
+// Play: todo
+func Variance[T constraints.Float | constraints.Integer](numbers []T) float64 {
+	n := len(numbers)
+	if n == 0 {
+		return 0
+	}
+
+	avg := Average(numbers...)
+	var sum float64
+
+	for _, v := range numbers {
+		sum += (float64(v) - avg) * (float64(v) - avg)
+	}
+
+	return sum / float64(n)
+}
+
+// StdDev returns the standard deviation of numbers.
+// Play: todo
+func StdDev[T constraints.Float | constraints.Integer](numbers []T) float64 {
+	return math.Sqrt(Variance(numbers))
+}
+
+// Permutation calculate P(n, k).
+// Play: todo
+func Permutation(n, k uint) uint {
+	if n < k {
+		return 0
+	}
+
+	nFactorial := Factorial(n)
+	nMinusKFactorial := Factorial(n - k)
+
+	return nFactorial / nMinusKFactorial
+}
+
+// Combination calculate C(n, k).
+// Play: todo
+func Combination(n, k uint) uint {
+	if n < k {
+		return 0
+	}
+
+	nFactorial := Factorial(n)
+	kFactorial := Factorial(k)
+	nMinusKFactorial := Factorial(n - k)
+
+	return nFactorial / (kFactorial * nMinusKFactorial)
+}
--- a/mathutil/mathutil_exmaple_test.go
+++ b/mathutil/mathutil_exmaple_test.go
@@ -178,7 +178,7 @@ func ExampleAverage() {
 	fmt.Println(result2)

 	// Output:
-	// 1
+	// 1.5
 	// 1.3
 }

@@ -478,3 +478,51 @@ func ExampleDiv() {
 	// 0.5
 	// 0
 }
+
+func ExampleVariance() {
+	result1 := Variance([]int{1, 2, 3, 4, 5})
+	result2 := Variance([]float64{1.1, 2.2, 3.3, 4.4, 5.5})
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+
+	// Output:
+	// 2
+	// 2.42
+}
+
+func ExampleStdDev() {
+	result1 := TruncRound(StdDev([]int{1, 2, 3, 4, 5}), 2)
+	result2 := TruncRound(StdDev([]float64{1.1, 2.2, 3.3, 4.4, 5.5}), 2)
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+
+	// Output:
+	// 1.41
+	// 1.55
+}
+
+func ExamplePermutation() {
+	result1 := Permutation(5, 3)
+	result2 := Permutation(5, 5)
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+
+	// Output:
+	// 60
+	// 120
+}
+
+func ExampleCombination() {
+	result1 := Combination(5, 3)
+	result2 := Combination(5, 5)
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+
+	// Output:
+	// 10
+	// 1
+}
--- a/mathutil/mathutil_test.go
+++ b/mathutil/mathutil_test.go
@@ -143,11 +143,22 @@ func TestAverage(t *testing.T) {

 	assert := internal.NewAssert(t, "TestAverage")

-	assert.Equal(0, Average(0, 0))
-	assert.Equal(1, Average(1, 1))
+	tests := []struct {
+		numbers  []int
+		expected float64
+	}{
+		{[]int{0}, 0},
+		{[]int{1, 1, 1}, 1},
+		{[]int{1, 2, 3, 4}, 2.5},
+		{[]int{1, 2, 3, 4, 5}, 3},
+	}

-	avg := Average(1.2, 1.4)
-	assert.Equal(1.3, RoundToFloat(avg, 1))
+	for _, tt := range tests {
+		assert.Equal(tt.expected, Average(tt.numbers...))
+	}
+
+	avg := Average(1.1, 1.2, 1.3, 1.4)
+	assert.Equal(1.25, avg)
 }

 func TestSum(t *testing.T) {
@@ -413,3 +424,116 @@ func TestDiv(t *testing.T) {
 	assert.Equal(math.Inf(-1), Div(-8, 0))
 	assert.Equal(true, math.IsNaN(Div(0, 0)))
 }
+
+func TestVariance(t *testing.T) {
+	t.Parallel()
+
+	assert := internal.NewAssert(t, "TestVariance")
+
+	testIntNumbers := []struct {
+		numbers  []int
+		expected float64
+	}{
+		{[]int{0}, 0},
+		{[]int{1, 1, 1}, 0},
+		{[]int{1, 2, 3, 4}, 1.25},
+		{[]int{1, 2, 3, 4, 5}, 2.0},
+	}
+
+	for _, tt := range testIntNumbers {
+		assert.Equal(tt.expected, TruncRound(Variance(tt.numbers), 2))
+	}
+
+	testFloatNumbers := []struct {
+		numbers  []float64
+		expected float64
+	}{
+		{[]float64{0}, 0},
+		{[]float64{1, 1, 1}, 0},
+		{[]float64{1.1, 2.2, 3.3, 4.4}, 1.51},
+	}
+
+	for _, tt := range testFloatNumbers {
+		assert.Equal(tt.expected, TruncRound(Variance(tt.numbers), 2))
+	}
+}
+
+func TestStdDev(t *testing.T) {
+
+	t.Parallel()
+
+	assert := internal.NewAssert(t, "TestStdDev")
+
+	testIntNumbers := []struct {
+		numbers  []int
+		expected float64
+	}{
+		{[]int{0}, 0},
+		{[]int{1, 1, 1}, 0},
+		{[]int{1, 2, 3, 4}, 1.118},
+		{[]int{1, 2, 3, 4, 5}, 1.414},
+	}
+
+	for _, tt := range testIntNumbers {
+		assert.Equal(tt.expected, TruncRound(StdDev(tt.numbers), 3))
+	}
+
+	testFloatNumbers := []struct {
+		numbers  []float64
+		expected float64
+	}{
+		{[]float64{0}, 0},
+		{[]float64{1, 1, 1}, 0},
+		{[]float64{1.1, 2.2, 3.3, 4.4}, 1.229},
+	}
+
+	for _, tt := range testFloatNumbers {
+		assert.Equal(tt.expected, TruncRound(StdDev(tt.numbers), 3))
+	}
+}
+
+func TestPermutation(t *testing.T) {
+	t.Parallel()
+
+	assert := internal.NewAssert(t, "TestPermutation")
+
+	tests := []struct {
+		n        uint
+		k        uint
+		expected uint
+	}{
+		{1, 1, 1},
+		{1, 0, 1},
+		{0, 1, 0},
+		{0, 0, 1},
+		{3, 2, 6},
+		{4, 2, 12},
+	}
+
+	for _, tt := range tests {
+		assert.Equal(tt.expected, Permutation(tt.n, tt.k))
+	}
+}
+
+func TestCombination(t *testing.T) {
+	t.Parallel()
+
+	assert := internal.NewAssert(t, "TestCombination")
+
+	tests := []struct {
+		n        uint
+		k        uint
+		expected uint
+	}{
+		{1, 1, 1},
+		{1, 0, 1},
+		{0, 1, 0},
+		{0, 0, 1},
+		{3, 2, 3},
+		{4, 2, 6},
+	}
+
+	for _, tt := range tests {
+		assert.Equal(tt.expected, Combination(tt.n, tt.k))
+	}
+}
--- a/random/random.go
+++ b/random/random.go
@@ -10,6 +10,7 @@ import (
 	"io"
 	"math"
 	"math/rand"
+	"os"
 	"time"
 	"unsafe"

@@ -274,7 +275,9 @@ func nearestPowerOfTwo(cap int) int {
 // random generate a random string based on given string range.
 func random(s string, length int) string {
 	// 确保随机数生成器的种子是动态的
-	rand.Seed(time.Now().UnixNano())
+	pid := os.Getpid()
+	timestamp := time.Now().UnixNano()
+	rand.Seed(int64(pid) + timestamp)

 	// 仿照strings.Builder
 	// 创建一个长度为 length 的字节切片
Author	SHA1	Message	Date
dudaodong	1eb793420e	doc: add Gurubase and update Sponsor text	2024-11-19 10:29:41 +08:00
dudaodong	05f9854945	Merge branch 'rc'	2024-11-19 10:26:41 +08:00
dudaodong	3be706e23f	doc: add doc for Permutation and Combination function	2024-11-19 10:25:32 +08:00
Kursat Aktas	b5e7312353	Introducing Lancet Guru on Gurubase.io (#271 )	2024-11-19 10:21:30 +08:00
dudaodong	95a894e53f	feat: add Permutation and Combination	2024-11-19 10:12:07 +08:00
dudaodong	8322951475	feat: add StdDev and fix bug of Average for math package	2024-11-18 17:01:27 +08:00
dudaodong	6b2c91b0f6	feat: add Variance for math package	2024-11-18 16:25:32 +08:00
dudaodong	ec161f335d	fix: update random seed when call random function	2024-11-14 16:27:22 +08:00
feng6917	d1a8f37a71	Correction of word assert spelling mistakes (#269 )	2024-11-12 19:15:23 +08:00