获取选定元素的键和索引Swift [英] Get key and indices of selected elements Swift

问题描述

我有一本字典，其中包含一组字典.

I have one dictionary that contains an Array of Dictionaries.

"other":(
    {
         "grocery_section" = other,
         name = test
    },
    {
         "grocery_section" = other,
         name = test1
    },
    {
         "grocery_section" = other,
         name = test2
    }
    ),
"c0f5d6c5-4366-d310c0c9942c": (
    {
         "grocery_section" = refrigerated,
         name = "Nondairy milk"

    },
    {
         "grocery_section" = other,
         name = "test
    }
)

现在，我想要的是键和索引，其中name = test .现在，我正在迭代字典并在其中获取

Now, What I want is the key and index where name = test. Right now I am iterating dictionary and inside that get the indexes of elements like

for (key, value) in list {
    print(key)
    print((value as! [String:String]).indices.filter { (value as! [String:String])[$0]["name"] == "test"})
}

它有效，但我认为它不是有效的方法.因此，需要一种更有效的方法. 主要问题是如何用另一个元素替换或更新该元素.例如，我要在name = test的两个元素中都添加status = "true".我也可以通过循环运行或查找元素并将其替换来做到这一点.但是我需要一些有效的方法.

It works but I don't think its efficient way. So, Need a more efficient way. And the main question is how to replace or update the element with another element. For example, I want to add status = "true" in both the elements where name = test. That too I can do by looping things or finding elements and replace it. But I need some efficient way to do so.

推荐答案

您可以使用flatMap和compactMap:

let matches = list.flatMap { key, value in
    // go through all elements in the array and convert the matching dictionaries in (key, index) pairs
    value.enumerated().compactMap { index, dict in
        dict["name"] == "test" ? (key, index) : nil
    }
}
print(matches)

示例输出:

[("other", 0), ("c0f5d6c5-4366-d310c0c9942c", 1)]

如果要避免同一密钥重复配对，可以使用map代替compactMap:

If you want to avoid repeated pairs for the same key, you can use map instead of compactMap:

let matches = list.map { key, value in
    (key, value.enumerated().compactMap { index, dict in
        dict["name"] == "test" ? index : nil
    })
}

示例输出:

[("other", [0]), ("c0f5d6c5-4366-d310c0c9942c", [1])]

内部compactMap将仅在名称匹配的项目上构建一个数组，而外部flatMap将使原本为二维的数组变平.

The inner compactMap will build an array made of on only the items that have the name matching, while the outer flatMap will flatten an otherwise bi-dimensional array.

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