Hi everybody I tried to import data from notepad file using k=load('a_1.txt') and save again with name b_1.But I need to make this in the loop so, I can load many files have different names like a_1 a_2......a_10. Then I will save them again in the

Hi everybody

I tried to import data from notepad file using k=load('a_1.txt') and save again with name b_1.But I need to make this in the loop so, I can load many files have different names like a_1 a_2......a_10. Then I will save them again in the loop with different names like b_1, b_2, b_3 .....b_10. I tried to use the

for x=1:6
    load(eval(sprintf('a%d', x));)
    z=eval(sprintf('a%d', x));
   save  eval(sprintf('b%d=z;', x))
end

How can I make this loop to load and save thses files.

Thanks for help

[Stephen23]

Using eval is an awful way to solve this task. The documentation explains much better (simpler, neater, faster, more robust, more efficient,...) ways to process a sequence of files:

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

And also this has been explained many times on this forum:

https://www.mathworks.com/matlabcentral/answers/57446-faq-how-can-i-process-a-sequence-of-files

About the worst solution would be to use eval, you might like to first know what the MATLAB documentation says about it: "A frequent use of the eval function is to create sets of variables such as A1, A2, ..., An, but this approach does not use the array processing power of MATLAB and is not recommended."

source: https://www.mathworks.com/help/matlab/matlab_prog/string-evaluation.html

You might also like to read what experienced MATLAB users say about what you are trying to do (hint: they strongly advise against it):

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

https://www.mathworks.com/matlabcentral/answers/57445-faq-how-can-i-create-variables-a1-a2-a10-in-a-loop

A much better solution is to load your data into one variable, and then simply access the data using indexing and/or fieldnames, e.g. if you use load then always load into an output variable. This will more efficient, neater, more robust, easier to check, easier to debug, faster,...

PS: Microsoft Notepad is a propriety text editor. I suspect you mean to write "text file", because "notepad files" do not exist.

[Jan]

Do I understand correctly: Actually you want to rename the files?

Trust Stephen's suggestion: Avoid eval completely.

Answer 1

[KSSV]

files = dir('*.txt') ;
N = length(files) ;
for i = 1:N
    data = load(files(i).name) ;
    % new file name
    newfile = strcat('b_',num2str(i),'.txt') ;
    save(newfile,'data','-ascii') 
end

Answer 2

[Stephen23]

To rename files use movefile.

If you only want to rename the files there is absolutely no point in wasting time reading the data into MATLAB and then saving a new file. movefile is simpler and faster.