writematrix is not creating a new .csv file for writing matrix to if it does not already exist.

Info sheet for writematrix function says that it will create a new file with the 'full filename path' if it does not already exits. This is not happening and I am getting a 'Cannot find 'full filename path' instead.

[Walter Roberson]

Are you possibly using the "WriteMode", "append" option?

If you are passing in a path with directory, does the directory already exist? The function will not create directories.

Answer 1

[Image Analyst]

Show the code where you're creating the folder name and the full file name. You seem to have forgotten to upload it. It should look something like

folder = 'c:\whatever'
if ~isfolder(folder)
    % Create folder if it doesn't exist.  Maybe writematrix does this for you
    % -- I'm not sure because you're saying it doesn't, so I'm doing it manually here.
    mkdir(folder)
end
baseFileName = 'My Data.csv';
fullFilename = fullfile(folder, baseFileName);
if isfile(fullFileName)
    % Delete any existing file with the same name.
    delete(fullFileName);
end
writeMatrix(myData, fullFileName);

Waiting for your reply, after you read this link of course:

TUTORIAL: How to ask a question (on Answers) and get a fast answer

[Amina Alihodzic]

@Image Analyst is it possible to get yout e-mail :) I have a few questions for you regarding steganography..

[Image Analyst]

Sorry, no. Ask them in Answers where everyone can benefit from the topic. I am not an expert in steganography so I'll probably just say "I don't know" to whatever you ask. I'm attaching a few demos.

Answer 2

[GJohnson2]

It looks like the writematrix function is not completed successfully, and throws a catch error.

The code is:

rfile_1 = sprintf('/Documents/Matlab/data/S%d/Exp%d/S%d_Exp%d_RIGHT_%s.csv', snum, exp_num, snum, exp_num, date_str);
try
    writematrix(SubDataVals, rfile_1);
catch
    fprintf('Cannot find %s\n',rfile_1);
end

[Walter Roberson]

Which operating system are you using that has "Documents" directly under the root directory ?

"Documents" is much more likely to be under the user's home directory, such as /Users/GJ2/Documents/Matlab/data/ and so on.

I do not see anywhere in your code where you are creating any directory Documents/Matlab/data/S%d/Exp%d that does not already exist.

Answer 3

[Image Analyst]

If you're doing something like

date_str = datestr(now)

date_str = '23-May-2022 12:49:11'

that won't work because it has colons in the string and you can't have colons in the filename anywhere except in the second position to separate the drive letter from the folder. To fix, get rid of the colons:

rfile_1 = strrep(rfile_1, ':', '') % Get rid of colons.