error in print function output name

When I try to run the following bit of script, MATLAB successfully generates the pdf in the directory, but an error pops up in the command window that says:

Output file XXX\MATLAB_Output\pdf_generation\Fig1.pdf was not created. The file name may not be valid

(XXX being properly printed as the directory location).

The most frustrating part is, the pdf was created, and opens fine! Please let me know if I am missing anything, I am trying to run this print within a for loop and it keeps ending my script too early.

oo = 1;
fig_name = append(pwd,'\MATLAB_Output\pdf_generation\Fig',string(oo),'.pdf')
figure(oo) % this figure is already defined, so it here pops up when this runs
print(fig_name,'-dpdf')

[Steven Lord]

Rather than using append like this, does the error still occur if you use fullfile to assemble the full path to the PDF file?

Can you share a small segment of code (no more than 10 lines or so) that creates a figure window (and its contents) that cause this error to occur when you try to print it to a PDF file? Without being able to create such a figure it'll probably be quite difficult if not impossible to investigate the cause of this error.

What operating system are you using (Windows, Linux, Mac?)

peaks;

 
z =  3*(1-x).^2.*exp(-(x.^2) - (y+1).^2) ... 
   - 10*(x/5 - x.^3 - y.^5).*exp(-x.^2-y.^2) ... 
   - 1/3*exp(-(x+1).^2 - y.^2) 
 

cd(tempdir)
fig_name = fullfile(pwd, "Figure" + 1 + ".pdf")

fig_name = "/tmp/Figure1.pdf"

print(fig_name, '-dpdf')

ls

Editor_fstbu  Figure1.pdf

[Matthew Marandola]

Unfortunately I don't think I can share too much more of this code for proprietary reasons, but I am operating windows and the figure is generated using a separate function I have not written.

When I attempt this with peaks, it seems to work fine. Must be something nested away in the plot.

I implemented a try statement and, for my purposes, this solved the issue. But I am still nagged as to why this happened. The error takes place in line 90 of print

[Walter Roberson]

fig_name = append(pwd,'\MATLAB_Output\pdf_generation\Fig',string(oo),'.pdf')

I have to wonder whether the total filename exceeds the limits of 259 characters ?

[Matthew Marandola]

I'm at 107 characters when including the full file path. Weird stuff huh. Thanks for your help guys

[dpb]

@Steven Lord didn't ask for more of the propietary code, he asked if you could manage to create the job that causes the error other than from the full code. What if you change something in the figure and then try or if you can just attach the figure as a .fig file...

Other alternatives -- change the path to local, change the output file type to see if the symptom remains, goes away or changes.

The other thing I'd not is that the error message doesn't say the filename is NOT valid; it says it MAY be -- I'd infer from that it's an error being thrown that isn't diagnosed completely internally -- looking at the top level of the print routine, it doesn't contain that error message text, at least with R2021b which I have installed here. Maybe poke around inside and see if you can find the condition(s) that are being tested to cause the message...

Answer 1

[Nivedita]

It seems like the issue is related to how MATLAB handles file paths and the "print" function. One common issue is the use of backslashes (`\`) in file paths, which can sometimes cause problems. MATLAB handles file paths more reliably when forward slashes (`/`) are used.

Here’s a revised version of your script that uses forward slashes instead:

oo = 1;
fig_name = append(pwd, '/MATLAB_Output/pdf_generation/Fig', string(oo), '.pdf');
figure(oo); % this figure is already defined, so it here pops up when this runs
print(fig_name, '-dpdf');

Additionally, you might want to ensure that the directory structure exists before attempting to save the file. You can use "mkdir" to create the necessary directories if they do not exist:

oo = 1;
output_dir = fullfile(pwd, 'MATLAB_Output', 'pdf_generation');
if ~exist(output_dir, 'dir')
    mkdir(output_dir);
end
fig_name = fullfile(output_dir, ['Fig', string(oo), '.pdf']);
figure(oo); % this figure is already defined, so it here pops up when this runs
print(fig_name, '-dpdf');

This script uses "fullfile" to construct the file path, which ensures that the correct file separators are used for your operating system. It also checks if the output directory exists and creates it if necessary.

Try running the revised script and see if it resolves the issue.

[dpb]

"...MATLAB handles file paths more reliably when forward slashes (`/`) are used."

Have you any evidence supporting this?

The OP responded that is on Windows for which the file separation character IS the backslash so your code will produce the same thing as he's already using or that @Steven Lord's example would suggesting the same thing.

Now, we don't know that @Matthew Marandola did try the change with his figure, but it doesn't seem likely to matter on WIndows platform. But, it is still a good suggestion to try to see if the symptoms did change.

[Stephen23]

"One common issue is the use of backslashes (`\`) in file paths, which can sometimes cause problems. MATLAB handles file paths more reliably when forward slashes (`/`) are used. "

It is odd what AI comes up with ¯\_(ツ)_/¯

[Walter Roberson]

The OP responded that is on Windows for which the file separation character IS the backslash

Actually...

The internal Windows file seperation character is forward slash. The use of backwards slash is in a wrapper layer.

[dpb]

I guess I never looked into the bowels, Walter...but in MATLAB with fullfile() it'll build the name with the system user-visible separator character. I suppose that could lead to some issue regarding such a translation internally.

It still would be interesting to delve into the internals and see what it is testing to throw that particular "...may be..." error message.