Telling MATLAB to wait
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I'm doing a project and when I run my code, instead of MATLAB plotting the results after every time-step, it's only plotting the end result. I tried using the wait and timeout function but was unsuccessful. If anyone could help me put a 0.5 sec delay so MATLAB has the chance to plot that would be great!
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Matt Fig
2011-5-12
2 个投票
Do you call PLOT after every time-step? After every time-step, call PLOT then cal DRAWNOW. You can also call PAUSE with a time-to-pause argument, but I doubt this is what you really want to do with your code.
更多回答（1 个）
Sean de Wolski
2011-5-12
pause(0.5)
14 个评论
Doug Hull
2011-5-12
To flush the graphics queue, DRAWNOW is preferred.
Zach
2011-5-12
Sean de Wolski
2011-5-12
Yes, but if only drawnow is used then it'll still zip right through and show only the end result. Hence is they want to see each time point, a pause() is still necessary.
Sean de Wolski
2011-5-12
x = 1:10;
y = x.^2;
figure;
hold on
for ii = 1:10
plot(x(ii),y(ii),'r*');
drawnow;
pause(0.5) %comment me to see the difference
end
Matt Tearle
2011-5-12
Well, it's not showing only the end result, it's just that it's too quick for the eye to catch the intermediate steps.
Sorry, I'm a pedant. But the bottom line is correct: use drawnow to flush the queue *and* (usually) pause to control the animation timing.
Matt Fig
2011-5-12
Also, it would depend on what the user meant by timestep. I was picturing a lengthy calculation that would allow for more of a natural pause using DRAWNOW.
Also, setting the axis limits at the start is always a good idea for these types of things!
x = 1:10;
y = x.^2;
figure;
axis([0 10 0 100])
hold on
for ii = 1:10
plot(x(ii),y(ii),'r*');
sort(rand(3000)); % Simulate lengthy calculation
drawnow;
end
Matthew Simoneau
2011-5-12
FYI, I opened up a related discussion in a new question: http://www.mathworks.com/matlabcentral/answers/7309-is-pause-a-superset-of-drawnow
Jiro Doke
2011-5-12
@Matt Tearle,
I don't believe that "it's just too quick for the eye". I think it's because of the event queue issue. In other words, if you were to record the screen with a high-speed camera, you probably still won't be able to see the intermediate plots.
Unfortunately, I don't have a high-speed camera handy so I can't verify...
Matt Fig
2011-5-12
@Jiro and Matt Tearle,
I can see the intermediate plots if the ax-lims are held before the loop! Perhaps I need a faster computer...
Jiro Doke
2011-5-12
@Matt Fig,
You mean without "drawnow"??
@Matt Tearle,
Darn hidden comments. I think I didn't see the whole thread of comments, so I thought you were referring to the OP's question, not to Sean's comment.
Matt Fig
2011-5-12
@Jiro,
I mean the code I pasted in comment 6, but without the call to SORT. It is fast, but I definitely see it changing...
My new laptop should be here tomorrow, so I may not see it then.
Jiro Doke
2011-5-12
@Matt Fig,
Oh, I see. Yeah, I also see it with the drawnow. The question is whether it's updating faster than 30 Hz. My monitor refreshes at 60 Hz, so Nyquist frequency is 30.
Matt Tearle
2011-5-13
Thanks, Jiro. I think you've just made a business case for me needing a new computer... :)
Ghenam Dahmane
2022-11-4
thanks so match
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