How to use a nested loop for multiple CSV

Hi, I am having some trouble with the following problem. I did some testing and tested 5 materials, 3 times each therefore I have files called a_1, a_2, a_3, b_1, b_2 etc.

I want to create a loop where I can open the csv files, read the first 2 columns for each file column 1 = variable X, column 2 =Variable Y, and then find averages for X and Y variables in 'A', 'B', 'C' (A = a_1, a_2, a_3 etc)

This is the code I have so far but I am having issues with doing the correct mean operations and finding the correct area under graph per file as that is not working

for f = 1:5
    Lab = ['a_'; 'b_'; 'c_';'d_';'e_'];
    
    for n = 1:3
        filename = ([Lab(f,:),num2str(n),'.csv']); 
        Test= csvread(filename,1,0);
        Extension_Or = Test(:,1);
        Force_Or = Test(:,2);  
        %Subtract noise 
        Ext_sub = Test(2,1);
        F_sub   = Test(2,2); 
       
        %start at 0 
        Extension(f,n,:) = Extension_Or(:,1) - Ext_sub; 
        Force(f,n,:) = Force_Or(:,1) - F_sub; 

        %Calculate area under graph 
        Area_Test(f) = trapz(Extension(f,n,:), Force(f,n,:));
end 
Extension_Average = mean(Extension); 
end 

[Bob Thompson]

This is the code I have so far but I am having issues with doing the correct mean operations and finding the correct area under graph per file as that is not working

What do you mean by 'correct'? What type of results are you seeing, and how do they differ from what you were expecting?

[Sue MM]

The area_Test isnt working because of the Trapz if I just do it in terms of n it gives me 3 values for the 3 different files instead of spanning across the rows

similar with extension_average

[Bob Thompson]

For both trapz and mean you can set a dimension input, which I believe is what you need. Try:

Area_Test(f) = trapz(Extension(f,n,:), Force(f,n,:),1); % For rows dimension

And the same adjustment for rows of mean.

[Sue MM]

Unfortunately it still gives me the error: Error using trapz (line 62)

X must be a vector.

[Bob Thompson]

Maybe try

Area_Test(f) = trapz([Extension(f,n,:), Force(f,n,:)],1); % Concatonate the two together

Unfortunately, I don't have a perfect solution for you, as I haven't personally used trapz, and don't know how exactly your data should be organized. If the above doesn't work then I would suggest pulling up the documentation of trapz and reviewing it yourself, as that is all I will be able to do.

Feel free to ask any further clarification questions, and I'm sure we will help as we can.