save animation in subplot

I'm using

while
    drawnow;hold off
end

to create an animation. But this animation is just the 6th position as in subplot(2,3,6) (or through next tile repeatedly). To save this animation to the computer while not keeping the other subplots 1~5, what to do?

[Walter Roberson]

??

That is an infinite loop. Inside the infinite loop, you request that the graphics queue be flushed, and you turn off hold . But you do not do anything else -- no drawing at all, no recording of previously drawn material.

It is not clear what you are trying to do?

[feynman feynman]

thanks for your answer. I omitted '%draw something' as in your code

Answer 1

[Walter Roberson]

ax6 = subplot(2,3,6);

count = 0;
while true
    %draw something
    count = count + 1;
    filename = fullfile(SAVEDIRECTORY, "image" + count + ".png");
    exportgraphics(ax6, filename);
end

[feynman feynman]

however, does this approach work for .avi? If I have the following:

v = VideoWriter("file.avi");v.FrameRate=5;open(v);
while...
        ...
        frame = getframe(gcf);writeVideo(v,frame);
end

I directly inserted your code but didn't work since File format 'avi' is not valid for export.

[Walter Roberson]

That looks like it would work.

File format avi is valid for VideoWriter.

You would not have any exportgraphics() in this case.

[feynman feynman]

good to hear that. Then how does ax6 = subplot(2,3,6) get in without exportgraphics()?

[Walter Roberson]

You have getframe(gcf) which captures the image of the entire current figure.

Note that you could also getframe(ax6) if you wanted to capture subplot(2,3,6) only.

[feynman feynman]

thanks a lot, almost worked. But there's the following issues:

when

subplot24=subplot(2,2,[2;4]);
...
    frame = getframe(subplot24);writeVideo(v,frame);

Error using VideoWriter/writeVideo (line 368)

Frame must be 903 by 1616

when

subplot2=subplot(2,2,2);
...
    frame = getframe(subplot2);writeVideo(v,frame);

Error using VideoWriter/writeVideo (line 368)

Frame must be 379 by 677

[Walter Roberson]

Unfortunately, getframe() results can end up being slightly different sizes. The exact size of axes depends upon the tick labels.

So you need something like

v = VideoWriter("file.avi");v.FrameRate=5;open(v);
first_frame = true;
while...
        ...
        frame = getframe(gcf);
        if first_frame
            frame_size = size(frame.cdata);
            remembered_size = frame_size(1:2);
            first_frame = false;
        else
            frame.cdata = imresize(frame.cdata, remembered_size);
        end
        writeVideo(v,frame);
end

[Walter Roberson]

subplot24=subplot(2,2,[2;4]);
%...
subplot2=subplot(2,2,2);

subplot24 is expected to be about twice the size of subplot2 . You will have trouble writing both of them to the same video, unless you imresize() to a common size.

[feynman feynman]

amazing, thanks so much!