# Golang 实现Map Reduce Filter

By [Robin](https://paragraph.com/@robin-8) · 2023-02-26

---

    package main
    
    import (
        "fmt"
        "strconv"
    )
    
    // map reduce filter and pippline
    
    func itemsFilter(items []map[string]string, f func(map[string]string) bool) []map[string]string {
        newSlice := make([]map[string]string, 0)
        for _, item := range items {
            if f(item) {
                newSlice = append(newSlice, item)
            }
        }
        fmt.Println("itemsFilter result: ", newSlice)
        return newSlice
    }
    
    func mapToString(items []map[string]string, f func(map[string]string) string) []string {
        newSlice := make([]string, 0)
        for _, item := range items {
            newSlice = append(newSlice, f(item))
        }
        fmt.Println("mapToString resutl: ", newSlice)
        return newSlice
    }
    
    func fieldSum(items []string, f func(string) int) int {
        var sum int
        for _, item := range items {
            sum += f(item)
        }
        return sum
    }
    
    func main() {
        var users = []map[string]string{
            {
                "name": "张三",
                "age":  "18",
            },
            {
                "name": "李四",
                "age":  "22",
            },
            {
                "name": "王五",
                "age":  "20",
            },
            {
                "name": "赵六",
                "age":  "-10",
            },
            {
                "name": "孙七",
                "age":  "60",
            },
            {
                "name": "周八",
                "age":  "10",
            },
        }
        validUsers := itemsFilter(users, func(user map[string]string) bool {
            age, ok := user["age"]
            if !ok {
                return false
            }
            intAge, err := strconv.Atoi(age)
            if err != nil {
                return false
            }
            if intAge < 18 || intAge > 35 {
                return false
            }
            return true
        })
    
        ageSlice := mapToString(validUsers, func(user map[string]string) string {
            return user["age"]
        })
    
        sum := fieldSum(ageSlice, func(age string) int {
            intAge, _ := strconv.Atoi(age)
            return intAge
        })
        fmt.Printf("用户年龄累加结果: %d\n", sum)
    }

---

*Originally published on [Robin](https://paragraph.com/@robin-8/golang-map-reduce-filter)*