golang 数组随机排序
董洪臣 人气:0前言
目前接到一个推荐数据的需求，需要将数据库中获取到的数据进行随机排序后返回给用户。考虑了一下，有两种使用方式，一种是通过数据库 order by rand() ，还有一种就是本文需要使用到的代码处理
具体实现步骤如下
1.引入库
代码如下：
import ( "fmt" "math/rand" "time" )
2.组装数据并排序(方案一)
代码如下：
type CategoryEntity struct {
GrouponId int64 //团ID
MerchandiseId int64 //商品ID
CategoryId int64 //分类ID
CategoryTitle string //分类名称
}
func main() {
data := make([]CategoryEntity, 10)
data[0] = CategoryEntity{GrouponId: 0, MerchandiseId: 1117891, CategoryId: 726, CategoryTitle: "蔬菜"}
data[1] = CategoryEntity{GrouponId: 1, MerchandiseId: 1110162, CategoryId: 1505, CategoryTitle: "调料调味"}
data[2] = CategoryEntity{GrouponId: 2, MerchandiseId: 1117822, CategoryId: 746, CategoryTitle: "水果"}
data[3] = CategoryEntity{GrouponId: 3, MerchandiseId: 1115770, CategoryId: 1408, CategoryTitle: "个人护理"}
data[4] = CategoryEntity{GrouponId: 4, MerchandiseId: 1116528, CategoryId: 732, CategoryTitle: "肉"}
data[5] = CategoryEntity{GrouponId: 5, MerchandiseId: 1116526, CategoryId: 727, CategoryTitle: "休闲食品"}
data[6] = CategoryEntity{GrouponId: 6, MerchandiseId: 1117188, CategoryId: 728, CategoryTitle: "粮油调味"}
data[7] = CategoryEntity{GrouponId: 7, MerchandiseId: 1117379, CategoryId: 726, CategoryTitle: "蔬菜"}
data[8] = CategoryEntity{GrouponId: 8, MerchandiseId: 1118166, CategoryId: 1005, CategoryTitle: "居家百货"}
data[9] = CategoryEntity{GrouponId: 9, MerchandiseId: 1117377, CategoryId: 746, CategoryTitle: "水果"}
fmt.Println("随机前:", data)
//如果不使用rand.Seed(seed int64)，每次运行，得到的随机数会一样
rand.Seed(time.Now().Unix())
//采用rand.Shuffle，将切片随机化处理后返回
rand.Shuffle(len(data), func(i, j int) { data[i], data[j] = data[j], data[i] })
fmt.Println("随机后:", data)
}
3.组装数据并排序(方案二)
代码如下：
type CategoryEntity struct {
GrouponId int64 //团ID
MerchandiseId int64 //商品ID
CategoryId int64 //分类ID
CategoryTitle string //分类名称
}
func main() {
data := make([]CategoryEntity, 10)
data[0] = CategoryEntity{GrouponId: 0, MerchandiseId: 1117891, CategoryId: 726, CategoryTitle: "蔬菜"}
data[1] = CategoryEntity{GrouponId: 1, MerchandiseId: 1110162, CategoryId: 1505, CategoryTitle: "调料调味"}
data[2] = CategoryEntity{GrouponId: 2, MerchandiseId: 1117822, CategoryId: 746, CategoryTitle: "水果"}
data[3] = CategoryEntity{GrouponId: 3, MerchandiseId: 1115770, CategoryId: 1408, CategoryTitle: "个人护理"}
data[4] = CategoryEntity{GrouponId: 4, MerchandiseId: 1116528, CategoryId: 732, CategoryTitle: "肉"}
data[5] = CategoryEntity{GrouponId: 5, MerchandiseId: 1116526, CategoryId: 727, CategoryTitle: "休闲食品"}
data[6] = CategoryEntity{GrouponId: 6, MerchandiseId: 1117188, CategoryId: 728, CategoryTitle: "粮油调味"}
data[7] = CategoryEntity{GrouponId: 7, MerchandiseId: 1117379, CategoryId: 726, CategoryTitle: "蔬菜"}
data[8] = CategoryEntity{GrouponId: 8, MerchandiseId: 1118166, CategoryId: 1005, CategoryTitle: "居家百货"}
data[9] = CategoryEntity{GrouponId: 9, MerchandiseId: 1117377, CategoryId: 746, CategoryTitle: "水果"}
fmt.Println("随机前:", data)
//如果不使用rand.Seed(seed int64)，每次运行，得到的随机数会一样
rand.Seed(time.Now().Unix())
length := len(data)
for i := 0; i < length; i++ {
exchange(data, rand.Intn(length), i)
}
fmt.Println("随机后:", data)
}
// 交换数据
func exchange(data []CategoryEntity, i, j int) {
data[i], data[j] = data[j], data[i]
}
总结
整体比较简单，但是需要注意的有两点：
1：golang中 rand的使用方式，如果不使用rand.Seed(seed int64)，每次运行，得到的随机数会一样
2：方案一种采用rand.Shuffle+匿名函数，将切片随机化处理后返回。
3：方案二使用golang特有的数组交换方式：
func exchange(data []CategoryEntity, i, j int) {
data[i], data[j] = data[j], data[i]
}
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