将两个切片合并到映射的方法

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我有一个以切片形式返回 2 个变量的函数，我想将这两个切片作为键值对合并到一个映射中。问题是无法找到一种方法来单独迭代每个切片并将它们添加为键和值。 当前的实现正在迭代所有价格，并将每个价格添加到城镇键中。

package main

import (
    "fmt"
    "math/rand"
    "time"
)

func main() {
    cities, prices := citiesAndPrices()
    towns := groupSlices(cities, prices)
    for cities := range towns {

        fmt.Println(cities, prices)
    }

}

func citiesAndPrices() ([]string, []int) {
    rand.Seed(time.Now().UnixMilli())
    cityChoices := []string{"Berlin", "Moscow", "Chicago", "Tokyo", "London"}
    dataPointCount := 100
    cities := make([]string, dataPointCount)
    for i := range cities {
        cities[i] = cityChoices[rand.Intn(len(cityChoices))]
    }
    prices := make([]int, dataPointCount) 
    for i := range prices {
        prices[i] = rand.Intn(100)
    }
    return cities, prices
}

func groupSlices([]string, []int) map[string]int {
    cities, prices := citiesAndPrices()
    towns := make(map[string]int)
    for _, cities := range cities {
        for _, prices := range prices {
            towns[cities] = prices
            break
        }
    }
    return towns
}

正确答案

您必须将 groupslice 函数返回为 map[string][]int

这是给您的提示：

seed 与 rand.seed 方法不同，可以安全地并发使用。 source.

所以你可以调用它一次，而不是在每个调用函数上。这将加快您的应用程序的速度。

我认为这就是您想要的代码。

package main

import (
    "fmt"
    "math/rand"
    "time"
)

func main() {
    rand.Seed(time.Now().UnixNano())
    cities, prices := citiesAndPrices()
    towns := groupSlices(cities, prices)
    fmt.Println()
    total := 0
    for c, p := range towns {
        fmt.Println(c, p)
        total += len(p)
    }
    fmt.Println()
    fmt.Println("total must 200, found :", total) // total must be 200
}

func citiesAndPrices() ([]string, []int) {
    cityChoices := []string{"Berlin", "Moscow", "Chicago", "Tokyo", "London"}
    dataPointCount := 100
    cities := make([]string, dataPointCount)
    prices := make([]int, dataPointCount)
    for i := range cities {
        cities[i] = cityChoices[rand.Intn(len(cityChoices))]
        prices[i] = rand.Intn(100)
    }
    fmt.Println("inside citiesAndPrices func")
    fmt.Println(cities)
    fmt.Println(prices)
    fmt.Println("done run citiesAndPrices func\n")
    return cities, prices
}

func groupSlices(c1 []string, p1 []int) map[string][]int {
    c2, p2 := citiesAndPrices()
    towns := make(map[string][]int)
    for i, t := range c1 {
        // this is for cities1 and price1
        if towns[t] == nil {
            towns[t] = make([]int, 0)
        }
        towns[t] = append(towns[t], p1[i])

        // this is for cities2 and price2
        if towns[c2[i]] == nil {
            towns[c2[i]] = make([]int, 0)
        }
        towns[c2[i]] = append(towns[c2[i]], p2[i])
    }
    return towns
}

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