Access Sub-fields of multiple different-named fields in struct

Question

Nathan Moorman 2022-9-30

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https://ww2.mathworks.cn/matlabcentral/answers/1815100-access-sub-fields-of-multiple-different-named-fields-in-struct

回答： Walter Roberson 2022-9-30

I am trying to find an efficient way to grab data from lower-level fields of a struct. The top-level struct, s, has fields a, b, c, and each of those has different subfields, but they all share subfield x. Ideally, I would like to have a single line that would let me get a vector or cell of those values, something like:

>> out = s.([a,b,c]).x;
>> out = {'str1', 'str2', 'str3'}

So far, the best way I have come up with is:

out = cell(1,3);
f = fieldnames(s);
for i = 1:3
    out{i} = s.(f{i}).x;
end

But it seems like there should be a better, ideally loop-free, way to do this. Any ideas?

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Answer 1

Walter Roberson 2022-9-30

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在 MATLAB Online 中打开

struct2cell(structfun(@(F)F.x, s, 'UniformOutput', 0))

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Answer 2

Cel Kulasekaran 2022-9-30

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If you want to access a dynamic structure, s, it must evaluate to a single valid field name. I don't think there is much penalty in the loop here, do you have control of the construction of s? Perhaps re-consider that datastructure.