How to insert a string to a variable name

Hi everyone,

I am trying to insert a string as a variable name, my code is below but file name doesn't read A as 'sub-x421m9_'. At the end I want my file name to be sub-x421m9_

sub_ID={'sub-x421m9_'};
for k=0
    A = eval('sub_ID');
    [R,P]=corrcoef(sub1);
    save(A,'R');
end

[Stephen23]

Why do you need such an indirect and obfuscated way just to define the filename?

What specifically is stopping you from simply passing the filename itself?

Answer 1

[Steven Lord]

Should you try to create variables with dynamic names like this? The general consensus is no. That Answers post explains why this is generally discouraged and offers several alternative approaches.

In addition, sub-x421m9_ is not a valid variable name in MATLAB.

isvarname('sub-x421m9_')

ans = logical
   0

Variable names may only contain letters, numbers, and/or the underscore character. The - character is not allowed. When you try to eval that, it is interpreted as trying to subtract the variable (or result of a function call with 0 inputs and 1 output) named x421m9_ from the variable (or result of a function call etc.) named sub.

If all you wanted to do was use that as a file name, that's easy. I'm going to switch to a temporary directory:

cd(tempdir)
mkdir dir1829478
cd dir1829478

There is no file in this directory:

ls

Now make some sample data to save:

sampleDataToSave = 1:10; 

and save it.

filename = {'sub-x421m9_'};
save(filename{1}, 'sampleDataToSave')

Note that the file now exists:

ls

sub-x421m9_.mat

and contains the variable sampleDataToSave.

whos('-file', filename{1})

  Name                  Size            Bytes  Class     Attributes

  sampleDataToSave      1x10               80  double              

Answer 2

[Walter Roberson]

sub_ID={'sub-x421m9_'};
for k=0
    A = sub_ID{k+1};
    [R,P]=corrcoef(sub1);
    save(A,'R');
end