89 lines
2.1 KiB
Markdown
89 lines
2.1 KiB
Markdown
# golang 中map 和slice 索引速度比较
|
||
|
||
## 主文件
|
||
|
||
```go
|
||
package main
|
||
|
||
var max = 100
|
||
var Slice = make([]int, max+10)
|
||
var Map = make(map[int]int)
|
||
|
||
func init() {
|
||
for i := 0; i < max; i++ {
|
||
Slice[i] = i
|
||
Map[i] = i
|
||
}
|
||
}
|
||
|
||
// 查找算法可以优化，本文对于常用无序查找做比较
|
||
func SearchSlice(i int) int {
|
||
for _, v := range Slice {
|
||
if v == i {
|
||
return v
|
||
}
|
||
}
|
||
return -1
|
||
}
|
||
|
||
func SearchMap(i int) int {
|
||
return Map[i]
|
||
}
|
||
```
|
||
|
||
## 测试文件
|
||
|
||
```go
|
||
package main
|
||
|
||
import "testing"
|
||
|
||
func BenchmarkSearchMap(b *testing.B) {
|
||
for i := 0; i < b.N; i++ {
|
||
_ = SearchMap(i % max)
|
||
}
|
||
}
|
||
|
||
func BenchmarkSearchSlice(b *testing.B) {
|
||
for i := 0; i < b.N; i++ {
|
||
_ = SearchSlice(i % max)
|
||
}
|
||
}
|
||
|
||
func BenchmarkSlice(b *testing.B) {
|
||
for i := 0; i < b.N; i++ {
|
||
_ = Slice[i%max]
|
||
}
|
||
}
|
||
```
|
||
|
||
## 测试结果
|
||
|
||
max = 100
|
||
|
||
```bash
|
||
BenchmarkSearchMap-16 94148293 12.7 ns/op 0 B/op 0 allocs/op
|
||
BenchmarkSearchSlice-16 49473447 23.6 ns/op 0 B/op 0 allocs/op
|
||
BenchmarkSlice-16 187461336 6.46 ns/op 0 B/op 0 allocs/op
|
||
```
|
||
|
||
max = 10000
|
||
|
||
```bash
|
||
BenchmarkSearchMap-16 43147364 27.6 ns/op 0 B/op 0 allocs/op
|
||
BenchmarkSearchSlice-16 968623 1159 ns/op 0 B/op 0 allocs/op
|
||
BenchmarkSlice-16 187649472 6.42 ns/op 0 B/op 0 allocs/op
|
||
```
|
||
|
||
Max = 1000000
|
||
|
||
```bash
|
||
BenchmarkSearchMap-16 15015690 90.1 ns/op 0 B/op 0 allocs/op
|
||
BenchmarkSearchSlice-16 441436 104242 ns/op 0 B/op 0 allocs/op
|
||
BenchmarkSlice-16 182620702 6.58 ns/op 0 B/op 0 allocs/op
|
||
```
|
||
|
||
|
||
|
||
在一些特定优化条件下，可以尝试用slice，效果会比map好，比如把10^6^级的查找优化成3级10^2^查找, 对于一些结构体，可以根据某些特征分类或预先根据特征值排序
|