Why do I get the error "Invalid or deleted object." for the following code?

When I run the code for the first time, I get this error. However when I run it for a second time my code is able to run through to completion.

start = pi;
points = 250; % decrease to increase speed of marker
end_ = 0;
disc = pi/16;
theta = linspace(pi,0,points);
rho = sin(theta);
theta2 = linspace(0,pi,points);
rho2 = -sin(theta2);
p = polarscatter(theta(1),rho(1),'o','Filled','red');
for i = 0:15
    interval = linspace(start+i*disc,end_+i*disc,points);
    interval2 = linspace(end_+i*disc,start+i*disc,points);
    polarplot(interval,rho)
    hold on
    for k = 2:length(interval)
        p.XData = interval(k);
        p.YData = rho(k);
        drawnow 
    end
    pause(0.1)
    polarplot(interval2,rho2)
    for k = 2:length(interval2)
        p.XData = interval2(k);
        p.YData = rho2(k);
        drawnow
    end
    pause(0.1)
end
disp('Finished.')

Answer 1

[Adam Danz]

The reason you're getting the error is because you're updating p.XData where p is the output to polarscatter() however your call to polarplot() overwrites that axis so p is gone.

A solution is to grab the axis handle of polarscatter(), hold the axis, and pass the handle to your two calls to polarplot().

Grab the handle, hold the axis

p = polarscatter(theta(1),rho(1),'o','Filled','red');
ph = p.Parent; %axis handle 
hold(ph, 'on')

Pass the handle to polarplot()

polarplot(ph,interval,rho)

[Omar Ahmed]

Thanks!