How to address multiple subfields of a structure at once?

Question

Matthias Stangl 2016-10-13

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https://ww2.mathworks.cn/matlabcentral/answers/307053-how-to-address-multiple-subfields-of-a-structure-at-once

回答： Matthias Stangl 2016-10-13

Hi all,

I have a simple programming question, which might be easy for some of you, but I just can’t find the answer: If I have multiple fields of a structure, how can I address the same variable of multiple subfields at once?

Here is an example:

x(1).a = 10;
x(2).a = 20;
x(3).a = 30;

Now I want a vector of all the a-subfields, like:

result = [10, 20, 30]

I was trying this, but it doesn’t work:

result = x(1:3).a;

Or I want to assign a different value to multiple a-subfields at once. I was trying this, but it doesn’t work:

x(1:3).a = 10;

I know that I can solve this in a for-loop, like:

for i = 1:length(x)
   x(i).a = 10;
end

But is there a simpler solution without a loop for this problem?

Thanks!

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Answer 1

KSSV 2016-10-13

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https://ww2.mathworks.cn/matlabcentral/answers/307053-how-to-address-multiple-subfields-of-a-structure-at-once#answer_238738

编辑：KSSV 2016-10-13

在 MATLAB Online 中打开

You can access the result like:

   result = [x(1:3).a] 
or 
   result = [x(:).a]

Replacing the fields I think loop is one option and other way is to use structfun. I tried to implement this but could not get it. Hope some one will answer it.

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Stephen23 2016-10-13

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Matthias Stangl's "Answer" moved here:

Thats very good and super easy, thanks a lot! However, this only solved the question about "reading" of values. Is there also a similar solution to "write" values, as described in the second part of my question. Or do I actually need to solve this in a loop:

I want to assign a different value to multiple a-subfields at once. I was trying this, but it doesn’t work:

x(1:3).a = 10;

Thanks!

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