Error in saving plot as PNG?

for i = 3386:5100
    %mkdir 8PSK
    x = load(['frame_snr016QAM' num2str(i) '.mat']);
    sps = 8;
    eyediagram( x.frame , sps)
    set(get(gcf, 'Children'), 'Visible', 'off')
    
    cd 16QAM
    pause(0.5)
saveas(gcf,['frame_snr016QAM' num2str(i) '.png']);

cd ..
close
end

error

Error using print (line 83)
PNG library failed: Write Error.

Error in saveas (line 181)
        print( h, name, ['-d' dev{i}] )
 

I want to save the plot of eyediagram in a folder. but it was working correctly now i am facing png library failed issue. Please assist

Answer 1

[Image Analyst]

If you have R2020, try exportgraphics() instead of saveas().

And you can also use isfolder(). Replace

if ~exist(outdir, 'dir'); mkdir(outdir); end

with

if ~isfolder(outdir)
    mkdir(outdir);
end

[john karli]

it works but how can i save it ?

[Walter Roberson]

exportgraphics() saves directly to file -- it is a new routine intended to replace print() and saveas()

Answer 2

[Walter Roberson]

outdir = '16QAM';
if ~exist(outdir, 'dir'); mkdir(outdir); end

for i = 3386:5100
    in_filename = sprintf('frame_snr016QAM%d.mat', i);
    out_filename = fullfile(outdir, sprintf('frame_snr016QAM%d.png', i));
    x = load(in_filename);
    sps = 8;
    eyediagram(x.frame, sps)
    set(get(gcf, 'Children'), 'Visible', 'off')
    pause(0.5)
    saveas(gcf, out_filename);
    close
end

[john karli]

it is giving the same error:

Error using print (line 83)

PNG library failed: Write Error.

Error in saveas (line 181)

print( h, name, ['-d' dev{i}] )

[Walter Roberson]

How large is your axes (how many pixels) ?

Do you have write access to the array 16QAM ?

[john karli]

its .mat file contain 1x1024x2 complex variable. the code have save 3385 pngs but after that it gives error of PNG library

[Walter Roberson]

There is a chance that file descriptors are leaking. You could periodically

fclose('all')

but that will not help if the file descriptor is leaked inside the png library.

Which operating system are you using? If it is MacOS or Linux I might be able to suggest some tools to check file usage. Windows would take me more research.

[john karli]

I am using windows. the error is same

[Walter Roberson]

You might be able to use Process Explorer to find out whether your process is accumulating open files;

https://docs.microsoft.com/en-us/sysinternals/downloads/process-explorer