golang 数组随机排序的实现

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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