variable name with variation

I have a very basic question. I want to write a loop in MATLAB which creates 4 separate variables with "a" number "in the name" and put 22 in each of them. Something like this:

for a=1:4
   star'{a}'=22
end

But this does not seem to identify "a" separately and not as a part of the variable name. How should I use syntax to do that?

Answer 1

[Adam Danz]

What you're describing is called dynamic variable naming and it should be avoided. Instead, you can store the intended variable name and its value in a cell array as shown below.

star = cell(4,2); 
for a=1:4
   star{a,1} = 'a'; % in reality, this would vary across iterations
   star{a,2} = 22;  % in reality, this would vary across iterations
end

Or, you could store it in a structure,

star = struct(); 
for a=1:4
    star.('a') = 22; % assuming 'a' and will vary across iterations
end

See this outline for reasons to avoid using dynamic variable names.

[Adam Danz]

Shokufeh Sadaghiani's answer moved here as a comment.

Thanks, this perfectly works for this example, but what I actually want to do is to save 4 NIFTI files with names: e1-e4 as variables: e1-e4 and I want to do that with a loop. Is that possibe? Or is there a better way for doing that?

[Adam Danz]

Perhaps this example will help, showing how to change the description field of a NIFTI file.

https://www.mathworks.com/help/images/ref/niftiwrite.html#mw_61f073b4-f52e-4082-be49-2ca791e34cec

The 'a' in either of my demos can be changed to anything you want.

Example:

sprintf('e%d',1)

[Stephen23]

"...I actually want to do is to save 4 NIFTI files with names: e1-e4 as variables: e1-e4 and I want to do that with a loop. Is that possibe?"

It is certainly possible, but only if you want to force yourself into writing slow, complex, obfuscated, buggy code that is hard to debug. Read this to know why: https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

"Or is there a better way for doing that?"

Yes, you use indexing just like Adam Danz's answer shows, or the MATLAB documentation shows:

https://www.mathworks.com/help/matlab/import_export/process-a-sequence-of-files.html

[Shokufeh Sadaghiani]

I am new to MATLAB and coding. Thank you both.

[Adam Danz]

The use of dynamic variable names is common for newbies and it's good you learned not to use them early on.