MATLAB: How to save variable with different name inside loop

antipatternbuggydynamic variable namesevalevilsaving variable inside for loop with auto namingslowugly

I have variable with name x with varying size of some 10000*2. 2 columns are fix, row value changing. I am getting that variable inside the for loop.

How should I autosave variable inside loop ? Autonaming for every loop condition will be useful.

Please reply. I want to use variable and call it in some other code.

Best Answer

Dynamically naming variables is not recommended. It is slow and buggy. Check the following link:

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

A better approach would be saving them in a structure by using a for loop. For instance:

for k = 1:10
  A.(sprintf('RandomVariable_%d', k)) = rand;
end

The above code will automatically name the fields of struct. Your variables will be stored in a struct, which will be nice. Hope this helps.

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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: Saving a new table for every loop iteration

Don't do that. Dynamic variable creation is a bad idea and totally unnecessary.

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

Use a cell array.

 data = cell(variable_max,1);
 column_name  = cell(variable_max,1);
 %and preallocate other variables, this is important if you want your code to be faster
 for k=1:variable_max
   ...
   ...
   column_name {k,1} = ...
   data{k,1} = dataextract(...)
 end

Now you have all your tables under one variable. You can access them by indexing.

Best Answer

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

MATLAB: Saving a new table for every loop iteration

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