前言
目前接到一個推薦數據的需求,需要將數據庫中獲取到的數據進行隨機排序后返回給用戶。考慮了一下,有兩種使用方式,一種是通過數據庫 order by rand() ,還有一種就是本文需要使用到的代碼處理
具體實現步驟如下
1.引入庫
代碼如下:
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import ( "fmt" "math/rand" "time" ) |
2.組裝數據并排序(方案一)
代碼如下:
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type CategoryEntity struct { GrouponId int64 //團ID MerchandiseId int64 //商品ID CategoryId int64 //分類ID CategoryTitle string //分類名稱 } 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: "調料調味"} data[2] = CategoryEntity{GrouponId: 2, MerchandiseId: 1117822, CategoryId: 746, CategoryTitle: "水果"} data[3] = CategoryEntity{GrouponId: 3, MerchandiseId: 1115770, CategoryId: 1408, CategoryTitle: "個人護理"} data[4] = CategoryEntity{GrouponId: 4, MerchandiseId: 1116528, CategoryId: 732, CategoryTitle: "肉"} data[5] = CategoryEntity{GrouponId: 5, MerchandiseId: 1116526, CategoryId: 727, CategoryTitle: "休閑食品"} data[6] = CategoryEntity{GrouponId: 6, MerchandiseId: 1117188, CategoryId: 728, CategoryTitle: "糧油調味"} data[7] = CategoryEntity{GrouponId: 7, MerchandiseId: 1117379, CategoryId: 726, CategoryTitle: "蔬菜"} data[8] = CategoryEntity{GrouponId: 8, MerchandiseId: 1118166, CategoryId: 1005, CategoryTitle: "居家百貨"} data[9] = CategoryEntity{GrouponId: 9, MerchandiseId: 1117377, CategoryId: 746, CategoryTitle: "水果"} fmt.Println("隨機前:", data) //如果不使用rand.Seed(seed int64),每次運行,得到的隨機數會一樣 rand.Seed(time.Now().Unix()) //采用rand.Shuffle,將切片隨機化處理后返回 rand.Shuffle(len(data), func(i, j int) { data[i], data[j] = data[j], data[i] }) fmt.Println("隨機后:", data) } |
3.組裝數據并排序(方案二)
代碼如下:
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type CategoryEntity struct { GrouponId int64 //團ID MerchandiseId int64 //商品ID CategoryId int64 //分類ID CategoryTitle string //分類名稱 } 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: "調料調味"} data[2] = CategoryEntity{GrouponId: 2, MerchandiseId: 1117822, CategoryId: 746, CategoryTitle: "水果"} data[3] = CategoryEntity{GrouponId: 3, MerchandiseId: 1115770, CategoryId: 1408, CategoryTitle: "個人護理"} data[4] = CategoryEntity{GrouponId: 4, MerchandiseId: 1116528, CategoryId: 732, CategoryTitle: "肉"} data[5] = CategoryEntity{GrouponId: 5, MerchandiseId: 1116526, CategoryId: 727, CategoryTitle: "休閑食品"} data[6] = CategoryEntity{GrouponId: 6, MerchandiseId: 1117188, CategoryId: 728, CategoryTitle: "糧油調味"} data[7] = CategoryEntity{GrouponId: 7, MerchandiseId: 1117379, CategoryId: 726, CategoryTitle: "蔬菜"} data[8] = CategoryEntity{GrouponId: 8, MerchandiseId: 1118166, CategoryId: 1005, CategoryTitle: "居家百貨"} data[9] = CategoryEntity{GrouponId: 9, MerchandiseId: 1117377, CategoryId: 746, CategoryTitle: "水果"} fmt.Println("隨機前:", data) //如果不使用rand.Seed(seed int64),每次運行,得到的隨機數會一樣 rand.Seed(time.Now().Unix()) length := len(data) for i := 0; i < length; i++ { exchange(data, rand.Intn(length), i) } fmt.Println("隨機后:", data) } // 交換數據 func exchange(data []CategoryEntity, i, j int) { data[i], data[j] = data[j], data[i] } |
總結
整體比較簡單,但是需要注意的有兩點:
1:golang中 rand的使用方式,如果不使用rand.Seed(seed int64),每次運行,得到的隨機數會一樣
2:方案一種采用rand.Shuffle+匿名函數,將切片隨機化處理后返回。
3:方案二使用golang特有的數組交換方式:
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func exchange(data []CategoryEntity, i, j int) { data[i], data[j] = data[j], data[i] } |
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原文鏈接:https://blog.csdn.net/dong945221578/article/details/116067051