Saving plots during the run of a for-loop

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

Answer 1

[Mahith Madhana Kumar]

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

[David Fletcher]

copied your code (the only change I made was to change the save path to something that exists on my system) and it ran fine on my system, saving all four of the graphs as Sine1.jpeg, Sine2.jpeg, Sine3.jpeg and Sine4.jpeg. No errors. Try creating/using a different folder

[Image Analyst]

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.

Answer 2

[David Fletcher]

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')

[Mahith Madhana Kumar]

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.

Answer 3

[Image Analyst]

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.

[Mahith Madhana Kumar]

Yes. I got it now. Its working wih the modifed code which I wrote earlier. I just have a question: Which answer should I accept in this case? I am sorry but am not entirely sure in this case.

[Image Analyst]

@Mahith Madhana Kumar, you can only accept one answer. Accept the one you think is best or helped you the most. The others you can "Vote" for, and you can Vote for as many answers as you want. Voting gives the answerer 2 reputation points just like Accepting does. Thanks.

[Mahith Madhana Kumar]

Allright thanks