dictionary - 映射重复键值对(如果不存在)

Question

以下是我的结构定义:

type test struct{
    Title  string
    State  string
    Counts int
}

我想通过以下方式映射结构对象成员 map[Title:map[State:Counts]]
这是成功执行此操作的代码

func main() {
    r := make(map[string]map[string]int)
    r1 := make(map[string]int)
    var ts []test

    ts = append(ts, test{Title: "Push 1",
        State:  "Active",
        Counts: 20})
    ts = append(ts, test{Title: "Push 1",
        State:  "InActive",
        Counts: 20})
    ts = append(ts, test{Title: "Push 1",
        State:  "Checked",
        Counts: 20})
    ts = append(ts, test{Title: "Push 1",
        State:  "Active",
        Counts: 23})

    ts = append(ts, test{Title: "Push 2",
        State:  "Active",
        Counts: 20})
    ts = append(ts, test{Title: "Push 2",
        State:  "InActive",
        Counts: 23})

    for _, t := range ts {
        r1[t.State] = t.Counts
        r[t.Title] = r1

    }
    fmt.Println("struct: ", ts)
    fmt.Println("map: ", r)
}

我面临的问题是没有 State: Checked的标题“Push 2”已附加上一个对象的Count值。
以下输出如下

struct: [{Push 1 Active 20} {Push 1 InActive 20} {Push 1 Checked 20} {Push 1 Active 23} {Push 2 Active 20} {Push 2 InActive 23}]
map: map[Push 1:map[Active:20 Checked:20 InActive:23] Push 2:map[Active:20 Checked:20 InActive:23]]

我编译的代码在去操场上。

Answer 1

r := make(map[string]map[string]int)仅创建一个 map ，没有任何条目。
r1 := make(map[string]int)也仅创建一个用于计数状态的 map ，但是您不需要一个 map ，每个不同的标题都需要一个单独的 map 。

因此，无需创建单个r1，而是根据需要创建内部 map 。遍历您的结构，并且当其标题没有内部映射时，请创建一个并将其存储在外部r映射中。

像这样:

for _, t := range ts {
    counts := r[t.Title]
    if counts == nil {
        counts = make(map[string]int)
        r[t.Title] = counts
    }
    counts[t.State]++

}

注意，计数操作可能只是 counts[t.State]++。

有了这个输出将是(在 Go Playground上尝试):

map:  map[Push 1:map[Active:2 Checked:1 InActive:1] Push 2:map[Active:1 InActive:1]]