I have a set of .mat files with random names. I want to import all those files from the directory using loop. Each file has 4 columns and I want to vertically concatenate each column from all the imported files. Please help with the code.

I have a set of .mat files with random names. I want to import all those files from the directory using loop. Each file has 4 columns and I want to vertically concatenate each column from all the imported files. Please help with the code.

Answer 1

[Avni Agrawal]

Hi @Kashish Jain,

I understand that you are trying to import all `.mat` files from a directory and concatenate their columns vertically, you can use MATLAB's `dir` function to list all the files, and then loop through each file to load and concatenate the data.

Here's a step-by-step guide with example code:

% Specify the directory containing the .mat files
directory = 'your_directory_path'; 

% Get a list of all .mat files in the directory
fileList = dir(fullfile(directory, '*.mat'));

% Initialize cell arrays to store concatenated columns
column1 = [];
column2 = [];
column3 = [];
column4 = [];

% Loop through each file
for i = 1:length(fileList)
    % Construct the full file path
    filePath = fullfile(directory, fileList(i).name);
    data = load(filePath);
    
    % Assuming the data is stored in a variable named 'dataMatrix'
    dataMatrix = data.dataMatrix;
    
    % Concatenate each column vertically
    column1 = [column1; dataMatrix(:, 1)];
    column2 = [column2; dataMatrix(:, 2)];
    column3 = [column3; dataMatrix(:, 3)];
    column4 = [column4; dataMatrix(:, 4)];
end

%Display the concatenated columns (optional)
disp('Concatenated Column 1:');
disp(column1);
disp('Concatenated Column 2:');
disp(column2);
disp('Concatenated Column 3:');
disp(column3);
disp('Concatenated Column 4:');
disp(column4);

• Set the `directory` variable to the path where your `.mat` files are located.
• Use `dir` to get a list of all files with a `.mat` extension in the specified directory.
• Initialize empty arrays (`column1`, `column2`, `column3`, `column4`) to store the concatenated data from each column.
• Construct the full path for each file using `fullfile`. Load each file using the `load` function.
• Extract the matrix (assumed to be named `dataMatrix` here) and concatenate each column vertically using the `;` operator.

I hope this helps!

[Walter Roberson]

More efficiently:

% Specify the directory containing the .mat files
directory = 'your_directory_path'; 

% Get a list of all .mat files in the directory
fileList = dir(fullfile(directory, '*.mat'));

numfiles = length(fileList);

datacell = cell(numfiles, 1);

% Loop through each file
for i = 1:length(fileList)
    % Construct the full file path
    filePath = fullfile(directory, fileList(i).name);
    data = load(filePath);
    
    % Assuming the data is stored in a variable named 'dataMatrix'
    datacell{i} = data.dataMatrix(:,1:4);
end

dataMatrix = cell2mat(datacell);