Do calculations in csv data one csv file at the time

I have several csv files. Want to perform calculations on the data in the csv file, for example calculating variable x. Then, I want one table with in the first column the filename of each csv file and then in the next column the calculated variable x. How can I do this? Newbie,so sorry for asking.

[Dyuman Joshi]

How does your query relate to MATLAB?

Can't the calculations be performed in the CSV file directly via Excel?

[Martin Kneyber]

Sure, but there are a lot of files and each files has a big number of rows - hence looking for a way to automate it

[Dyuman Joshi]

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

Use readtable or readmatrix to import the data, and their counter-parts writetable or writematrix to export the data.

Answer 1

[Voss]

Something like this; adjust as necessary.

% use dir() to get info about the relevant csv files:
csv_dir = '.';
F = dir(fullfile(csv_dir,'*.csv'));
filename = fullfile({F.folder},{F.name}).';

% preallocate x. I assume it's a scalar numeric for each file
N = numel(F);
x = zeros(N,1);

% loop over the files
for ii = 1:N
    
    % read each file (use the appropriate function with the appropriate options)
    data = readtable(filename{ii});
    
    % ...
    % calculate this_x based on data
    % ...
    
    % store this_x
    x(ii) = this_x;
    
end

% write file with file names and x values
T = table(filename,x);
writetable(T,'out.csv')

[Martin Kneyber]

Thank you !!!!!

[Voss]

You're welcome!

Answer 2

[Image Analyst]

See the FAQ for code samples to process a sequence of files:

Process a sequence of files

[Martin Kneyber]

Thank you!