无循环访问结构中的数据 [英] Accessing data in structures without loops

问题描述

我有一组字符串vals，例如:

I have a set of strings vals, for example:

vals = {'AD', 'BC'}

我还有一个结构info，其中的结构嵌套在与数组vals中的元素相对应的字段中(在此示例中为"AD"和"BC")，每个结构依次存储lastcontract字段中的数字.

I also have a struct info, inside of which are structs nested in fields corresponding to the elements in the array vals (that would be 'AD' and 'BC' in this example), each in turn storing a number in a field named lastcontract.

我可以使用for循环为每个vals提取lastcontract，如下所示:

I can use a for loop to extract lastcontract for each of the vals like this:

for index = 1:length(vals)
    info.(vals{index}).lastcontract
end

如果可能的话，我想找到一种没有循环的方式，但是我没有运气.我试过了:

I'd like to find a way of doing this without a loop if at all possible, but I'm not having luck. I tried:

info.(vals{1:2}).lastcontract

没有成功.我认为arrayfun可能是合适的方法，但是我找不到正确的语法.

without success. I think arrayfun may be the appropriate way, but I can't figure out the right syntax.

推荐答案

实际上，这里可以在没有显式循环的情况下(也不是arrayfun/cellfun)进行管理:

It is actually possible here to manage without an explicit loop (nor arrayfun/cellfun):

C = struct2cell(info);                  %// Convert to cell array
idx = ismember(fieldnames(info), vals); %// Find fields
C = [C{idx}];                           %// Flatten to structure array
result = [C.lastcontract];              %// Extract values

PS
在这里，cellfun比arrayfun更合适，因为您迭代vals(单元格数组).为了练习起见，这是cellfun的解决方案:

P.S
cellfun would be more appropriate here than arrayfun, because you iterate vals (a cell array). For the sake of practice, here's a solution with cellfun:

result = cellfun(@(x)info.(x).lastcontract, vals);

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