How can I access files from a matlab directory using a user input to select the file to plot the data? Using a For Loop

I have a .exe file while I can select the name of the folders I want to get the data from.

Then I get this by means of a user input and i get that in a .txt file.

I want to read the input of that .txt file and load the .mat file or workspace.mat from the specific folders that were selected.

Then maybe I only want channel one to be plotted or so on, but always according to the input.

But when I try to load, in a for loop, I am not able t come up with a solution for my problem.

Please Help.

 cd('results')
[status,cmdout]=system('get_file_names');

fid_sel=fopen('my_selection.txt');
foldernames=[];
a=fgetl(fid_sel);
idx=1;

while(ischar(a))
    foldernames{idx}=a;
    a=fgetl(fid_sel);
    idx=idx+1;
    disp(a);
end
fclose(fid_sel);

cd ..

% Channel selection for printout
CHSEL= [1,0,0]; %[Ch1, CH2, CH3]  Channel selection, 1..selected, 0.. not selected


% loop over foldernames and get the .mat files and print this.

for kk=1:length(foldernames)
    
  filename = sprintf ('\workspace.mat') 
  S = load(filename)
    
    load(foldernames,'\workspace.mat') % mat file from the folder in foldernames
    
    ydata=[];
    if (CHSEL(1))
        ydata(:,1) %= first channel from the loaded data
    end
    
  load('\workspace.mat','ydata')

    if (CHSEL(2))
        ydata(:,2) %= second channel from loaded data
    end
        
  load('\workspace.mat','ydata')
    
   if (CHSEL(3))
        ydata(:,3) %= third channel from loaded data
   end
    
        
   load('/workspace.mat','ydata')
    
    plot() % plot the graph
    hold on
    
    h1=figures(1);  
    hold off;

    title('Amplitude peaks over frequency')
    legend({'RX1','RX2','RX3'})
    xlabel('f_C_W (GHz)')
    ylabel('Peak Amplitudes (dB_F_S)')
    
    plot (y)
    
    %     title
    %     legend...
    %     ...
    
    
end

[Jan]

What is your question?

"But when I try to load, in a for loop, I am not able t come up with a solution for my problem."

Then please explain, what happens or which error you get. "Not able" ist hard to answer.

[Luciana Noronha]

>> postprocess

SV1_SEV3_001

-1

Warning: Escaped character '\w' is not valid. See 'doc sprintf' for supported special characters.

> In postprocess (line 44)

filename =

1×0 empty char array

Error using load

File name is empty.

Error in postprocess (line 45)

S = load(filename)

[Luciana Noronha]

So when I try to access the files, that I have stored on a folder, all in .workspace format, I can`t plot those results, that I selected

[Luciana Noronha]

I tried seeing some code online, but it says empty char array and I want to access all the data that looks like this in variables stored in .workspacemat. I have multiple folders with different variables and the results look like this:

57,5000000000000 57,5500000000000 57,6000000000000 57,6500000000000 57,7000000000000 57,7500000000000 57,8000000000000 57,8500000000000 57,9000000000000 57,9500000000000 58 58,0500000000000 58,1000000000000 58,1500000000000 58,2000000000000 58,2500000000000 58,3000000000000 58,3500000000000 58,4000000000000 58,4500000000000 58,5000000000000 58,5500000000000 58,6000000000000 58,6500000000000 58,7000000000000 58,7500000000000 58,8000000000000 58,8500000000000 58,9000000000000 58,9500000000000 59 59,0500000000000 59,1000000000000 59,1500000000000 59,2000000000000 59,2500000000000 59,3000000000000

[Luciana Noronha]

I want a for loop that access the data based on the data selection program and then I can access the folder selected in the Data Selection and plot the data.

Answer 1

[Jan]

The messages are clear: "Warning: Escaped character '\w' is not valid. See 'doc sprintf' for supported special characters." and "File name is empty". This shows, that the creation of the file name failed and the problem is not caused by the contents of the files.

The line:

filename = sprintf ('\workspace.mat')

replies an empty filename. Use:

% either
filename = 'workspace.mat';
% or
filename = sprintf('%s', '.\workspace.mat');

Starting a file name with a backslash is a strange idea. Do you mean the file in the current directory? Then use either '.\' as start of the file name or simply omit the path completely.

I do not know what ".workspace format" means. Do you mean .mat files?

"Look like this: 57,5000000000000 57,5500000000000 57,6000000000000 57,6500000000000 ..." is not useful here. By the way: Matlab uses dots, not commas, as decimal separator.

I guess, you want something like this:

for kk = 1:length(foldernames)
  % Use absolute path instead of relative file name:
  filename = fullfile(foldernames{kk}, 'workspace.mat'));
  ydata    = load(filename, 'ydata')
  ...
end

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

[madhan ravi]

+1 always crystal clear