How can I save multiple matrix and index them?

Hello,

I don't if it is even possible but I have 9 files with the same name except his number (1, ... 9) = "SiON_D6_L8.5_12Lyrs_NUMBER_CHANGE_HERE_umOfDistance_Ex.txt"

These txt files are 941x2 sized arrays. I need to open this file and find the maximum value within the values in the second column and then continue to do my accounts. The problem is that I am doing it one by one, that is, I have 9 files and I have to copy the program bellow nine times. My goal is to find the radius of the nine file and in the end I will plot the 9 radius together to compare.

Is it some way to do with a loop? Like I can index the file (1,...9) and when I want to access the file I just index it.

clear all;

file1 = load('SiON_D6_L8.5_12Lyrs_1umOfDistance_Ex.txt');     % open file
     
E1 = file1(:,2);            % get second column
Y1 = file1(:,1);            % get first column
M1 = max(E1(:));            % get max of the second column
 
m1 = M1*0.37;

endij1 = round(length(E1)/2);

 
 for i1 = 1:endij1
     
     if E1(i1) >= m1
         x1(i1) = Y1(i1);
         y1(i1) = E1(i1);
     end 
 end 
 
 for j1 = endij1:length(E1)
     
     if E1(j1) >= m1
         x21(j1) = Y1(j1);
         y21(j1) = E1(j1);
     end      
 end 

 for d1 = 1:length(x1)
     
     if x1(d1) ~= 0
        x_data1(d1) = x1(d1);
      
     else
       x_data1(d1) = 1000; 
     end
 end
     
a1 = min(x_data1);
b1 = max(x21);

radius1 = b1-a1;                                % radius 1

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
file2 = load('SiON_D6_L8.5_12Lyrs_2umOfDistance_Ex.txt');

E2 = file2(:,2);
Y2 = file2(:,1);
M2 = max(E2(:));
 
m2 = M2*0.37;

endij2 = round(length(E2)/2);

% As you can see to open the second file i'm copying the same code again but chaging the variables and file names. 

[Stephen23]

"Is it some way to do with a loop? Like I can index the file (1,...9) and when I want to access the file I just index it. "

Of course, just follow the examples in the MATLAB documentation:

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

[Tay]

Thanks, I used the sprintf to do it :))

[Stephen23]

https://web.archive.org/web/20211124063555/https://www.mathworks.com/matlabcentral/answers/576037-how-can-i-save-multiple-matrix-and-index-them

Answer 1

[KSSV]

txtFiles = dir("*.txt") ; 
N = length(txtFiles) ;
themax = zeros(N,1) ; 
% loop for each file
for i = 1:N
    data = importdata(txtFiles(i).name) ; % read the data 
    iwant(i) = max(data(:,2)) ;   % get the max of second column of data 
end

[Tay]

Thank you so much KSSV !!!

It worked but I need to take the first and the second column of each file because in the end I need to check them as you can see in my code.

I tried to do this (Line 5 and 6):

for i = 1:N-1
    data = importdata(txtFiles(i).name) ; % read the data 
    M(i) = max(data(:,2)) ;   % get the max of second column of data 
    m(i) = M(i)*0.37;

    E(i) = data(:,2);           %THIS TWO LINE IS NOT WORKING
    Y(i) = data(:,1);           %THIS TWO LINE IS NOT WORKING
    
    
    endhj(i) = round(length(E(i))/2);
    
    for h = 1:endhj
     
     if E(h) >= m
         x(h) = Y(h);
         y(h) = E(h);
     end 
 end 
 
 for j = endhj:length(E)
     
     if E(j) >= m
         x2(j) = Y(j);
         y2(j) = E(j);
     end      
 end 

 for d = 1:length(x)
     
     if x(d) ~= 0
        x_data(d) = x(d);
      
     else
       x_data(d) = 1000; 
     end
 end
     
a(i) = min(x_data);
b(i) = max(x2);

radius(i) = b(i)-a(i);
end
    

And a got this:

>> Untitled

Unable to perform assignment because the indices on the left side are not compatible with

the size of the right side.

Error in Untitled (line 12)

E(i) = data(:,2);

Is some way to do what I want to do or i have to copy and past my code for each file? You can see in the end I calculate the radius e I want to plot all them in the same graph.

Thanks again !!!

[KSSV]

E(i) = data(:,2);  

The above is wrong..you are saving a column,so LHS should be a matrix.

E(:,i) = data(:,2);

The above will work. It is advised to initiatlize the matrix before loop.

[Tay]

Thanks, it is working ! :)