From 0b5e88437194b54fb4115d33a5857c830fb8760d Mon Sep 17 00:00:00 2001
From: donutloop <marcel.edmund.franke@gmail.com>
Date: Sun, 3 Mar 2024 14:48:34 +0100
Subject: [PATCH] Strutil: HammingDistance func (#197)

* Strutil: HammingDistance func

The Hamming distance is the number of positions at which the corresponding symbols are different

* Add hamming distance doc
---
 docs/api/packages/strutil.md    | 33 ++++++++++++++++++++++++++++++++
 docs/en/api/packages/strutil.md | 34 +++++++++++++++++++++++++++++++++
 strutil/string.go               | 22 +++++++++++++++++++++
 strutil/string_example_test.go  | 13 +++++++++++++
 strutil/string_test.go          | 23 ++++++++++++++++++++++
 5 files changed, 125 insertions(+)

diff --git a/docs/api/packages/strutil.md b/docs/api/packages/strutil.md
index c378ce6..909161d 100644
--- a/docs/api/packages/strutil.md
+++ b/docs/api/packages/strutil.md
@@ -61,6 +61,7 @@ import (
 -   [ContainsAny](#ContainsAny)
 -   [RemoveWhiteSpace](#RemoveWhiteSpace)
 -   [SubInBetween](#SubInBetween)
+-   [HammingDistance](#HammingDistance)
 
 <div STYLE="page-break-after: always;"></div>
 
@@ -1495,4 +1496,36 @@ func main() {
     // abc
     // bc
 }
+```
+
+### <span id="HammingDistance">HammingDistance</span>
+
+<p>TBD</p>
+
+<b>函数签名:</b>
+
+```go
+HammingDistance(a, b string) (int, error)
+```
+
+<b>示例:</b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/strutil"
+)
+
+func main() {
+
+    result1, _ := strutil.HammingDistance("de", "de")
+    result2, _ := strutil.HammingDistance("a", "d")
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+
+    // Output:
+    // 0
+    // 1
+}
 ```
\ No newline at end of file
diff --git a/docs/en/api/packages/strutil.md b/docs/en/api/packages/strutil.md
index 2a5c1a5..b184c45 100644
--- a/docs/en/api/packages/strutil.md
+++ b/docs/en/api/packages/strutil.md
@@ -60,6 +60,8 @@ import (
 -   [ContainsAll](#ContainsAll)
 -   [ContainsAny](#ContainsAny)
 -   [RemoveWhiteSpace](#RemoveWhiteSpace)
+-   [SubInBetween](#SubInBetween)
+-   [HammingDistance](#HammingDistance)
 
 <div STYLE="page-break-after: always;"></div>
 
@@ -1496,4 +1498,36 @@ func main() {
     // abc
     // bc
 }
+```
+
+### <span id="HammingDistance">HammingDistance</span>
+
+<p>HammingDistance calculates the Hamming distance between two strings. The Hamming distance is the number of positions at which the corresponding symbols are different</p>
+
+<b>Signature:</b>
+
+```go
+HammingDistance(a, b string) (int, error)
+```
+
+<b>Example:</b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/strutil"
+)
+
+func main() {
+
+    result1, _ := strutil.HammingDistance("de", "de")
+    result2, _ := strutil.HammingDistance("a", "d")
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+
+    // Output:
+    // 0
+    // 1
+}
 ```
\ No newline at end of file
diff --git a/strutil/string.go b/strutil/string.go
index b8785fa..9aa423f 100644
--- a/strutil/string.go
+++ b/strutil/string.go
@@ -4,6 +4,7 @@
 package strutil
 
 import (
+	"errors"
 	"regexp"
 	"strings"
 	"unicode"
@@ -594,3 +595,24 @@ func SubInBetween(str string, start string, end string) string {
 
 	return ""
 }
+
+// HammingDistance calculates the Hamming distance between two strings.
+// The Hamming distance is the number of positions at which the corresponding symbols are different.
+// This func returns an error if the input strings are of unequal lengths.
+func HammingDistance(a, b string) (int, error) {
+	if len(a) != len(b) {
+		return -1, errors.New("a length and b length are unequal")
+	}
+
+	ar := []rune(a)
+	br := []rune(b)
+
+	var distance int
+	for i, codepoint := range ar {
+		if codepoint != br[i] {
+			distance++
+		}
+	}
+
+	return distance, nil
+}
diff --git a/strutil/string_example_test.go b/strutil/string_example_test.go
index 54adfda..a9bcb28 100644
--- a/strutil/string_example_test.go
+++ b/strutil/string_example_test.go
@@ -667,3 +667,16 @@ func ExampleSubInBetween() {
 	// abc
 	// bc
 }
+
+func ExampleHammingDistance() {
+
+	result, _ := HammingDistance("abc", "def")
+	fmt.Println(result)
+
+	result, _ = HammingDistance("name", "namf")
+	fmt.Println(result)
+
+	// Output:
+	// 3
+	// 1
+}
diff --git a/strutil/string_test.go b/strutil/string_test.go
index 10c6135..3d94af0 100644
--- a/strutil/string_test.go
+++ b/strutil/string_test.go
@@ -581,3 +581,26 @@ func TestSubInBetween(t *testing.T) {
 	assert.Equal("", SubInBetween(str, "a", ""))
 	assert.Equal("", SubInBetween(str, "a", "f"))
 }
+
+func TestHammingDistance(t *testing.T) {
+	assert := internal.NewAssert(t, "HammingDistance")
+
+	hd := func(a, b string) int {
+		c, _ := HammingDistance(a, b)
+		return c
+	}
+
+	assert.Equal(0, hd(" ", " "))
+	assert.Equal(1, hd(" ", "c"))
+	assert.Equal(1, hd("a", "d"))
+	assert.Equal(1, hd("a", " "))
+	assert.Equal(1, hd("a", "f"))
+
+	assert.Equal(0, hd("", ""))
+	assert.Equal(-1, hd("abc", "ab"))
+	assert.Equal(3, hd("abc", "def"))
+	assert.Equal(-1, hd("kitten", "sitting"))
+	assert.Equal(1, hd("ö", "ü"))
+	assert.Equal(0, hd("日本語", "日本語"))
+	assert.Equal(3, hd("日本語", "語日本"))
+}