Error using load: unable to read file

I tried loading a dataset but I am having errors.

The error message is following:

Error using load

Unable to read file 'C:\Users\###file location(omitted for my privacy)###\HC_DAY3_dataSet__30dB_time50s.mat'.

Input must be a MAT-file or an

ASCII file containing numeric data with same number of columns in each row.

Error in uiimport/runImportdata (line 469)

datastruct = load('-ascii', fileAbsolutePath);

Error in uiimport/gatherFilePreviewData (line 437)

[datastruct, textDelimiter, headerLines]= runImportdata(fileAbsolutePath, type);

Error in uiimport (line 259)

gatherFilePreviewData(fileAbsolutePath);

And when I tried loading the file again:

>> load('HC_DAY1_dataSet__30dB_time50s.mat')

Error using load

Unable to read MAT-file C:\Users\###file location###\HC_DAY1_dataSet__30dB_time50s.mat. Not a binary MAT-file. Try load -ASCII to read as text.

Does anyone know the solution? I just want to load the file. Thank you.

[Jan]

The message means, that the file has neither a valid MAT-file format nor is it a simple ASCII file.

What is the contents of the MAT file? How did you create it?

[Pol Cardona Rubio]

I have the same error.

When using matfile() inside a function inside a parfor loop it runs perfect at first, but if a stop and rerun I get this error and I can't recover the existing data of the .mat file. How is that possible?

In my case the .mat file is created once with an empty struct and then matfile(,writable) I add new data.

Answer 1

[Siraj]

Hi!

It seems that you're having trouble loading a MAT file using the "load" function. Whenever you try to load the file, you receive an error message saying, "Error using load, unable to read file".

If you are unable to load a MAT file using the "load" function, one possible reason could be that you don't have the necessary read permission for the file. In that case, you can try saving the file to a different location and then attempt to read it again.

Alternatively, if saving the file to a different location doesn't work, it's possible that the MAT file itself is corrupt. However, you may still be able to recover the non-corrupt variables within the MAT file by using the “matfile” command.

https://www.mathworks.com/help/matlab/ref/matlab.io.matfile.html

To better understand this, you can refer to the following code snippet:

% Generate random data
data1 = rand(100, 3);
data2 = rand(50, 4);
data3 = rand(200, 2);
v = rand(6,100);

% Save data as MAT file
save('random_data.mat', 'data1', 'data2', 'data3');
save('test.mat','v');

% Create a matfile object to access the MAT file
m = matfile("random_data.mat");

% Retrieve the variables from the MAT file
Newdata1 = m.data1; % Access 'data1' variable
Newdata2 = m.data2; % Access 'data2' variable
Newdata3 = m.data3; % Access 'data3' variable

You can also use the “matfile” command to recover the 'non-corrupt' portions of individual variables in a MAT file. Here's an example code demonstrating this:

m = matfile('test.mat');
size(m,'v')

ans = 1×2

6 100

This tells us that the variable 'v' in 'test.mat' is a 2-D array that has 6 rows and 100 columns (a total of 600 values). You can then try to read the 'non-corrupt' values in 'v' and store them in a new array 'vRec' as follows:

vRec = zeros(6,100); % pre-allocate for efficiency
for i = 1:6
    for j = 1:100
        try
            vRec(i,j) = m.v(i,j);  % store the value if it is not corrupt
        catch
            vRec(i,j) = NaN;  % if the value is corrupt/unreadable store 'NaN'    
            disp([int2str(i) ',' int2str(j) ' is unreadable.']);  % display the indices of the unreadable elements
        end
    end
end  

The above code will try to read all the 'non-corrupt' values in 'v' and store them in 'vRec'. The corrupt values in 'v' will be stored as 'NaNs'.

Hope this helps.