Saving plots during the run of a for-loop

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Hello,
I have couple of question on saving plots while a for-loop is continuously running. My code is:
interval=[0.01 0.1 0.5 1];
for i=1:length(x)
t=(0:interval(i):2*pi);
y = sin(t);
plot(t, y);
end
This code however shows the "Index exceeds the number of array elements (4)" error. I am not sure what is heppening here.
2) The second question is that I would like to save the output image file to a directory on my local folder as the fo-loop runs. The following code was used (for the same example above):
iinterval=[0.01 0.1 0.5 1];
for i=1:length(interval)
t=(0:interval(i):2*pi);
y = sin(t);
fig=figure(i);
plot(t, y);
basedir='C:\Users\Desktop\';
cd (basedir);
saveas(gca,fullfile(basedir,i),'.jpeg')
cd('C:\Users\');
end
The error shows: Unsupported format or extension: .jpg.
Basically I just need to see how the sine graphs vary with the size of the interval. Instead of manually doing things, I would love to have the plots saved to my destination as the for-loop runs but somehow I am running into more errors.
Thanks,
Mahith M
end

Accepted Answer

Mahith Madhana Kumar
Mahith Madhana Kumar on 24 Apr 2021
Edited: Mahith Madhana Kumar on 24 Apr 2021
Hi,
I managed to edit the code slightly and this time no error occurs. However, its saving only the first file in my specified directory instead of expected 4. Here is the modified code:
interval=[0.01 0.1 0.5 1];
for i=1:length(interval)
t=(0:interval(i):2*pi);
y = sin(t);
fig=figure(i);
plot(t, y);
path='C:\Users\Desktop\images\';
saveas(fig,fullfile(path,['Sine' num2str(i) '.jpeg']));
end
  2 Comments
Image Analyst
Image Analyst on 25 Apr 2021
path is a special keyword. Don't use it as the name for your folder or you may run into problems. Call it folder and assign it BEFORE your loop, not inside it.

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More Answers (2)

David Fletcher
David Fletcher on 24 Apr 2021
Edited: David Fletcher on 24 Apr 2021
1 - how big is x? If x is larger than interval you will get an indexing error.
2. Don't use the 'dot' in the saveas function (see below) Also may be just something you've done while entering the code into this forum, but you've spelt interval with two ii's at the start.
saveas(gca,fullfile(basedir,i),'jpg')
  1 Comment
Mahith Madhana Kumar
Mahith Madhana Kumar on 24 Apr 2021
Hi,
Thank for the answer. I guess it does not have to do with the typos or the 'dot' in the saveas function. I am attaching the screenshot of what I am seeing after making the edits which you had aid. Notice that I am getting an output this time though but again with an error message.

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Image Analyst
Image Analyst on 24 Apr 2021
You can use exportgraphics() if you have R2020a or later. Otherwise see my attached demo where I plot and save, then make a movie from them all.
  3 Comments

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