添加布隆过滤器

Author: hwholiday

.gitignore

@@ -0,0 +1,15 @@
+# Created by .ignore support plugin (hsz.mobi)
+### Go template
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+.idea
+# Test binary, build with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+

README.md

@@ -1,7 +1,13 @@
-###  recommend_code [推荐算法]基于用户的协同过滤算法
+###  recommend_code [推荐算法]
+    1: v1 基于用户的协同过滤算法[杰卡德相似度]
+    1: user_cf_by_cosine 基于用户的协同过滤算法[余弦夹角]
 
 ###  similarity_code [相似度算法]
      1: jaccard 相似度计算之杰卡德相似度
      2: cosine 相似度计算之余弦夹角
      
-###  red_envelope_code [二倍均值法] 可用于用户抢红包等
+###  average_code  [计算平均值]可用于用户抢红包等
+     1: red_envelope_code [二倍均值法] 可用于用户抢红包等
+     
+###  bloom_filter_code  [布隆过滤器]
+     1: bloom 布隆过滤器

red_envelope_code.go average_code/red_envelope_code.go

@@ -1,4 +1,4 @@
-package algorithm_coding
+package average_code
 
 import (
 	"fmt"

red_envelope_code_test.go average_code/red_envelope_code_test.go

@@ -1,4 +1,4 @@
-package algorithm_coding
+package average_code
 
 import "testing"
 

bloom_filter_code/bloom.go

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+package bloom_filter_code
+
+import (
+	"github.com/spaolacci/murmur3"
+	"github.com/willf/bitset"
+)
+
+//计算最佳的配置
+//https://hur.st/bloomfilter/
+//n代表元素的个数
+//p代表假阳率
+//m代表位图长度
+//k代表hash函数的个数
+type BloomFilter struct {
+	m uint64 //数组集合大小
+	k uint32 //hash函数个数
+	b *bitset.BitSet
+}
+
+func New(m uint64, k uint32) *BloomFilter {
+	return &BloomFilter{
+		m, k, bitset.New(uint(m)),
+	}
+}
+
+func (f *BloomFilter) Add(data []byte) {
+	for i := uint32(0); i < f.k; i++ {
+		f.b.Set(f.locate(data, i))
+	}
+}
+func (f *BloomFilter) Exist(data []byte) bool {
+	for i := uint32(0); i < f.k; i++ {
+		if !f.b.Test(f.locate(data, i)) { //一个不存在就绝对不存在
+			return false
+		}
+	}
+	return true
+}
+
+func (f *BloomFilter) locate(data []byte, seed uint32) uint {
+	return getHash(data, seed) % uint(f.m)
+}
+
+func getHash(data []byte, seed uint32) uint {
+	m := murmur3.New64WithSeed(seed)
+	_, _ = m.Write(data)
+	return uint(m.Sum64())
+}

bloom_filter_code/bloom_test.go

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+package bloom_filter_code
+
+import (
+	"github.com/spaolacci/murmur3"
+	"testing"
+)
+
+func TestMurmurNew128(t *testing.T) {
+	murmur := murmur3.New128()
+	_, _ = murmur.Write([]byte("1"))
+	v1, v2 := murmur.Sum128()
+	t.Log("v1", v1, "v2", v2)
+	t.Log("v1", v1%100, "v2", v2%100)
+}
+
+func TestNew(t *testing.T) {
+	m := New(3355, 23)
+	m.Add([]byte("a"))
+	m.Add([]byte("b"))
+	m.Add([]byte("c"))
+	t.Log(m.Exist([]byte("a")))
+	t.Log(m.Exist([]byte("c")))
+	t.Log(m.Exist([]byte("d")))
+}