首页 \ 问答 \ Swift：按键引用数组元素(Swift: reference to array element by key)

Swift：按键引用数组元素(Swift: reference to array element by key)

 我编写了自己的小函数来使用键在数组中查找元素。 但我确信在Swift中有一个可以使用的实现来将它放在一行中。 任何提示？  
func objectAtKey(array: [T], key: String) -> T? {
    for element in array {
        if element.name == key {
            return element
        }
    }
    return nil
}
 
 我也知道函数indexOf，但这返回一个索引，我必须用于进一步的访问。 我认为这比较慢：  
let index = array.indexOf({$0.name == key})

I have written my own small function to find an element in an array using a key. But I'm sure there is a ready to use implementation in Swift to get it in one line. Any hint? 
func objectAtKey(array: [T], key: String) -> T? {
    for element in array {
        if element.name == key {
            return element
        }
    }
    return nil
}
 
I also know function indexOf, but this return an index, I have to use for further access. I think this is slower: 
let index = array.indexOf({$0.name == key})

原文：https://stackoverflow.com/questions/39236301

更新时间：2022-09-06 09:09

最满意答案

 优雅的解决方案是提供与比较器运算符的intersect （例如，在C ++中 ）。 
 不幸的是，Matlab似乎并不支持这种功能/灵活性。  
 解决您的问题的方法是  
% convert structs into matrices
A = [[a(:).x];[a(:).y]]';
B = [[b(:).x];[b(:).y]]';
% intersect the equivalent representation
[C, ia, ib] = intersect( A, B, 'rows' );
% map back to original structs
c = a(ia);
 
 或者，您是否考虑使用从句柄类派生的类对象替换结构？ 有可能重载类的关系运算符 ，然后应该可以直接对类对象进行排序（我没有仔细研究过这个解决方案 - 这只是我头脑中的一个提议）。 

The elegant solution would have been to supply intersect with a comparator operator (like in , e.g., C++).
 Unfortunaetly, Matlab does not seem to support this kind of functionality/flexibility. 
A workaround for your problem would be 
% convert structs into matrices
A = [[a(:).x];[a(:).y]]';
B = [[b(:).x];[b(:).y]]';
% intersect the equivalent representation
[C, ia, ib] = intersect( A, B, 'rows' );
% map back to original structs
c = a(ia);
 
Alternatively, have you considered replacing your structs with class objects derived from handle class? It might be possible to overload the relational operators of the class and then it should be possible to sort the class objects directly (I haven't looked closely into this solution - it's just a proposal off the tip of my head).

Swift：按键引用数组元素(Swift: reference to array element by key)

最满意答案

相关问答

如何在MATLAB中初始化一个结构体数组？(How to initialize an array of structs in MATLAB?)[2022-05-26]

在Matlab中找到两个数组结构的交集(find the intersection of two array structs in Matlab)[2023-09-07]

在matlab中找到两条线的交点(Find the intersection point of two lines in matlab)[2023-06-15]

如何在Matlab中找到两个分布的交集(How to find intersection of two distribution in Matlab)[2022-11-12]

在MATLAB中找到两个结构数组的交集(Find the intersection of two arrays of structs in MATLAB)[2022-03-01]

两个数组之间的交集[重复](Intersection between two arrays [duplicate])[2023-06-19]

使用结构组合Matlab文件(Combining Matlab files using structs)[2022-05-11]

在Matlab中找到两个正态分布的交集(Find intersection of two normal distributions in Matlab)[2022-03-05]

在MATLAB中没有for循环的多个数组的交集(Intersection of multiple arrays without for loop in MATLAB)[2022-10-31]

搜索结构的matlab单元格数组中的索引(Search indices in matlab cell array of structs)[2022-02-25]

相关文章

最新问答