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Animation using plot inside for loop

Asked by Garrett Herbst on 8 Oct 2018
Latest activity Commented on by Stephen Wilkerson on 1 Dec 2018
I am trying to create an animation by using the plot function inside of a for loop. No matter what I do, I just get back the same still figure that opens. This figure opens over and over again when I close it.
figure(5)
for n = 1:1000
pos = xout(n,1)
x_origin = 0;
y_origin = 0;
x_bob = 0.75*sin(pos);
y_bob = -0.75*cos(pos);
plot([x_origin,x_bob],[y_origin,y_bob])
axis equal
xlim([-2 2])
ylim([-2 2])
drawnow
end
'xout' is a matrix with the angle values of a pendulum in the first column.

  3 Comments

Hi, kindly try
figure(5)
for n = 1:100
x_origin = 0;
y_origin = 0;
x_bob = 0.75*sin(n);
y_bob = -0.75*cos(n);
plot([x_origin,x_bob],[y_origin,y_bob])
axis equal
xlim([-2 2])
ylim([-2 2])
drawnow
end
I recommend you to take a look at xout() function. it is either updating too slow or something error within it.
I get a line swinging around like hands on a clock. Maybe put a pause(0.1) at the bottom of the loop to slow it down if you can't see it move.
Yes this: works fine as a .m file, but if put in a live script does not work, is there a way to animate a live script?
figure(5)
for n = 1:100
x_origin = 0;
y_origin = 0;
x_bob = 0.75*sin(n);
y_bob = -0.75*cos(n);
plot([x_origin,x_bob],[y_origin,y_bob])
axis equal
xlim([-2 2])
ylim([-2 2])
drawnow
end

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1 Answer

Answer by ANKUR KUMAR on 9 Oct 2018

clc
clear
h=figure
for n = 1:10
x_origin = 0;
y_origin = 0;
x_bob = 0.75*sin(n);
y_bob = -0.75*cos(n);
plot([x_origin,x_bob],[y_origin,y_bob])
axis equal
xlim([-2 2])
ylim([-2 2])
make_animation( h,n,'sample_animation.gif' )
pause(0.2) %you can enter the time in pause to change the loop
end
function make_animation( h,index,filename )
drawnow
frame = getframe(h);
im = frame2im(frame);
[imind,cm] = rgb2ind(im,256);
if index == 1
imwrite(imind,cm,filename,'gif', 'Loopcount',inf);
else
imwrite(imind,cm,filename,'gif','WriteMode','append');
end
end
If you are using older version than 2016a, then write make_animation in separate function and then run the program, as older version of MATLAB doesn't support writing functions inside in the script.

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