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How to combine the multiple .mat files of ecg to get a single file.

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I have 23 files(in .mat) of atrial fibrillation database. i want to combine all these mat files to get a matrix of (23*2500) where 2500 is the samples of each .mat files and 23 is the no of records or no. of files.
Please help!


Stephen Cobeldick
Stephen Cobeldick on 19 Oct 2020
What size do the .mat file contents have?
What are the names of the variable/s in the mat files? (hopefully they are all the same!)
What sequence do the filenames have?
SHRESTH GUPTA on 19 Oct 2020
i have attached a single .mat file and it has 1 row and 2500 samples as column.
the names are 04015m.mat, 04018m.mat etc.

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Accepted Answer

Stephen Cobeldick
Stephen Cobeldick on 19 Oct 2020
Edited: Stephen Cobeldick on 19 Oct 2020
This should get you started:
D = 'path to the folder where the files are saved';
S = dir(fullfile(D,'*.mat'));
for k = 1:numel(S)
F = fullfile(D,S(k).name);
T = load(F);
S(k).data = T.val;
M = vertcat(;


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SHRESTH GUPTA on 19 Oct 2020
its giving error as:
Reference to non-existent field 'val'.
Error in loadf (line 6)
S(k).data = T.val;
Stephen Cobeldick
Stephen Cobeldick on 19 Oct 2020
"Reference to non-existent field 'val'."
Your uploaded .mat file contains one variable named val, so I assumed that every file has the same variable name (answering your question is a lot easier if you give this kind of information, then we don't have to guess important details like this).
Here is a simple adaption of my answer that will work regardless of the variable name, it assumes that each .mat file contains exactly one variable. Replace the two lines with T in them with these two:
C = struct2cell(load(F));
S(k).data = C{1};

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More Answers (1)

Image Analyst
Image Analyst on 19 Oct 2020
Try this:
folder = pwd; %'path to the folder where the files are saved';
fileList = dir(fullfile(folder, '*.mat'));
numFiles = numel(fileList);
fileCounter = 0;
allValData = [];
for k = 1 : numFiles
fullFileName = fullfile(folder,fileList(k).name);
% Skip output file if it already exists.
if contains(fullFileName, 'allValData.mat', 'IgnoreCase', true)
fprintf('Reading %s (#%d of %d)...\n', fullFileName, k, numFiles);
storedStructure = load(fullFileName);
% If storedStructure has a field called val, concatenate it.
if isfield(storedStructure, 'val')
allValData = [allValData; storedStructure.val];
fileCounter = fileCounter + 1;
fieldnames(storedStructure) % Report what fields there are to the command window.
warningMessage = sprintf('WARNING : There is no Val field in file %d of %d:\n%s', k, numFiles, fullFileName);
fprintf('%s\n', warningMessage);
promptMessage = sprintf('%s\nDo you want to Continue processing,\nor Quit processing?', warningMessage);
titleBarCaption = 'Continue?';
buttonText = questdlg(promptMessage, titleBarCaption, 'Continue', 'Quit', 'Continue');
if contains(buttonText, 'Quit', 'IgnoreCase', true)
fprintf('Concatenated %d of %d files. Skipped %d files.\n', fileCounter, numFiles, numFiles - fileCounter);
fullOutputFileName = fullfile(folder, 'allValData.mat');
save(fullOutputFileName, 'allValData')
Did it work, or if not, did you see anything unusual?


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