MATLAB: Separate matrices out of struct

separate matrices out of struct

I have a struct having matrices of B1, B2, and B3. I want to make three separate matrices out of them available in the Workspace automatically with the help of a loop. How?

S = struct('B1',[1 2;3 4],'B2', [5 6; 7 8], 'B3', [9 10; 11 12] )

Best Answer

Why? Apparently the three matrices are related. Keeping them in a single struct shows this relationship. If you need to access one of them you can easily do this using assignment operations

X = S.B1

or dynamically

k = 2
field = sprintf('B%d',k) 
X = S.(field)

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MATLAB: How to write a1=1;a2=2;a3=3; from A

Do NOT do this

This would actually be horribly slow, pointlessly complex, obfuscated, and very buggy way to write your code. You would make your code hard to debug, and a pain to work with. Read this to know why:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

Using indexing would be simple, neat, and very efficient. You should use one array and indexing. Indexing is the solution you should be using, because it is the most efficient way to write MATLAB code, is simple, neat, and very easy to debug. Indexing is explained quite well in the MATLAB introductory tutorials, which are highly recommended for all beginners:

https://www.mathworks.com/help/matlab/getting-started-with-matlab.html

MATLAB: I have variables ‘Ereal2’,Ereal3,Ereal4,Ereal5.….so on…..how to call these variable in a single loop one by one.

Hi Ravi

I have to agree with Jonas. But if you insist to use indexing which is embedded to the variable name, you can take some ideas from the following piece of code

clear; clc;
for n=1:10
      % assign a value to each variable 
      strcmd=['Ereal' num2str(n) '=n^2 ;'];
      eval(strcmd);
      % display the value of each variable 
      disp(['Ereal' num2str(n) ' = ' num2str(eval(['Ereal' num2str(n)]))]);
end

The "key idea" is eval() function. You can find more info about this function on Mathworks help files

Best Answer

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MATLAB: How to write a1=1;a2=2;a3=3; from A

MATLAB: I have variables ‘Ereal2’,E​real3,Erea​l4,Ereal5.​….so on…..how to call these variable in a single loop one by one.

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MATLAB: I have variables ‘Ereal2’,Ereal3,Ereal4,Ereal5.….so on…..how to call these variable in a single loop one by one.