Run a calculation on multiple different .csv files and export the result

Hello all!

I am new to MATLAB but I am working on performing matrix calculations. I have the calculation code nailed down. The problem is I have 500+ .csv files that I have to read in, perform the calculation, and export each separately.

Is there a way to read in a folder of .csv files, perform my calculation on each, and then export the result of each 500+ calculations to one place?

%so this grabs one single .csv file and performs my calculation%
>> filename='THESISv1-DATA.csv';
M=csvread(filename);
>> S = sum(abs(M(2:end,:)-M(1:end-1,:)),1)

Answer 1

[Voss]

See my recent comment on a closely related question:

https://www.mathworks.com/matlabcentral/answers/2156490-subtracting-matrices-by-column-and-performing-a-summation#comment_3272485

[Lucas]

Thanks Voss!

[Voss]

You're welcome!

Answer 2

[Yukthi S]

Hi @Lucas

To automate the process of reading multiple .CSV files, performing operations and storing the results in one place, a simple “for” loop can be used.

The below code snippet will help you to get started.

% Define the input and output directories
inputDir = 'path/to/your/csv/files';  % Replace with input directory path
outputDir = 'path/to/save/results';   % Replace with output directory path
% Get a list of all CSV files in the input directory
csvFiles = dir(fullfile(inputDir, '*.csv'));
% Loop through each file
for k = 1:length(csvFiles)
    % Construct the full file path
    inputFile = fullfile(inputDir, csvFiles(k).name);
    
    % Read the CSV file
    M = csvread(inputFile);
    
    % Perform the calculation
    S = sum(abs(M(2:end,:) - M(1:end-1,:)), 1);
    
    % Construct the output file path
    [~, fileName, ~] = fileparts(csvFiles(k).name);
    outputFile = fullfile(outputDir, [fileName, '_result.csv']);
    
    % Save the result to a new CSV file
    writematrix(S, outputFile);
end
disp('Processing complete. Results saved.');

As specified in the code, the output .CSV files are saved in “outputDir”

The following MathWorks documentations have more information about the functions used in the code above:

“dir” : https://www.mathworks.com/help/matlab/ref/dir.html#:~:text=listing%20%3D%20dir(name)-,Description,-dir%20lists%20files

“fileparts” : https://www.mathworks.com/help/matlab/ref/fileparts.html#:~:text=ext%5D%20%3D%20fileparts(filename)-,Description,-%5Bfilepath%2C

[Lucas]

Thank you @Yukthi S. I really appreciate the help :). That makes sense and is easy to follow along.