Load multiple matlab data files and convert them to text

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Hi!
I have multiple matlab data files with different names (with ECG data from multiple patients) and I want to load them all and convert them to text.
Also, the data is in structure form so I have to do the following for each file:
signal = load('FileName')
data = [signal.val];
writematrix(data,'FileName.txt','Delimiter',',');
How can I do it all at the same time? Thank you a lot in advance :)

Accepted Answer

Image Analyst
Image Analyst on 4 Jul 2021
Code samples for processing a sequence of files are given in the FAQ:
  6 Comments
Image Analyst
Image Analyst on 4 Jul 2021
Edited: Image Analyst on 4 Jul 2021
myFolder = pwd; %'C:\Myfoldersdirectory';
filePattern = fullfile(myFolder, 'EKG*.mat');
theFiles = dir(filePattern);
for k = 1 : length(theFiles)
baseFileName = theFiles(k).name;
fullFileName = fullfile(theFiles(k).folder, baseFileName);
fprintf('Now reading input file : "%s".\n', fullFileName);
% Now do whatever you want with this file name,
% such as reading it in as an image array with imread()
storedStructure = load(fullFileName);
% See if it has a val field stored in the .mat file.
if ~isfield(storedStructure, 'val')
% Show what fieldnames there are:
fieldnames(storedStructure)
errorMessage = sprintf('Error: no field called "val" in file\n"%s".\n\nSkipping this file.', baseFileName);
uiwait(errordlg(errorMessage));
continue; % Skip to bottom of for loop and continue iterations.
end
data = -storedStructure.val;
fprintf('Now plotting %d values of data.\n', length(data));
plot(data, '-', 'LineWidth', 2);
hold on
% Create the output file name.
[~, baseFileNameNoExt, etc] = fileparts(baseFileName);
fullOutputFileName = fullfile(myFolder, [baseFileNameNoExt, '.txt']);
fprintf('Now writing output file : "%s".\n', fullOutputFileName);
writematrix(data, fullOutputFileName, 'Delimiter', ',');
end
I added some improvments and robustness checks, like printing out informational messages, adding comments, using descriptive variable names, plotting the data, and checking to see if the data is actually in the mat file to begin with. It never hurts to be extra robust.

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More Answers (1)

Sulaymon Eshkabilov
Sulaymon Eshkabilov on 4 Jul 2021
If you are talking about series of files (e.g: P1.txt, P2.txt, ...) to load and convert their contents, then this might be an option:
for ii = 1:numel(Files)
FName = strcat('P', num2str(ii), '.txt');
signal = load(FName)
data = [signal.val];
writematrix(data,'FileName.txt','Delimiter',',', 'WriteMode','append');
end
  1 Comment
Ana Gabriela Guedes
Ana Gabriela Guedes on 4 Jul 2021
Thank you!! But unfortunately the files I want to load are not in a series, so I cant use that :(
I'm doing this but how can I save each file with a different name (I want them to have the original name but in .txt format).
I'm trying to do this but it doesn't work:
myFolder = 'C:\Users\myfoldersdirectory';
filePattern = fullfile(myFolder, '*.mat'); % Change to whatever pattern you need.
theFiles = dir(filePattern);
for k = 1 : length(theFiles)
baseFileName = theFiles(k).name;
fullFileName = fullfile(theFiles(k).folder, baseFileName);
fprintf(1, 'Now reading %s\n', fullFileName);
% Now do whatever you want with this file name,
% such as reading it in as an image array with imread()
signal = load(fullFileName);
data = -[signal.val];
writematrix(data,'fullFileName.txt','Delimiter',',');
end
I know when I write 'fullFileName.txt' it creates a file with literaly the name 'fullFileName' but how can I change that so each file in the cycle has its own original name?

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