Single Figure Animation of moving points (without tails)

Hello, I am trying to plot an animated figure, where two points move. I need this to be done in a single MATLAB figure. Usually, this is done in a for loop, but this creates multiple figures and, for various reasons, I would prefer to avoid this. I would like to first declare a figure, appropriately prepare it (axes, grid, box, and so on) and then simply draw on it. The hold function doesn't create multiple figures, but it will leave "tails" (previous positions of the moving points). This is a simple working example (single point) of what I am trying to do (but it will leave tails).

P.S. I am aware of the comet function, but it leaves a tail.

%Random Data
x = (1:0.01:2*pi)';
y = sin(x);

%Animated Figure
figure;
hold on;
plot(x(1),y(1),'db');
axis([min(x) max(x) min(y) max(y)]);
xlabel('X', 'Interpreter','Latex');
ylabel('Y', 'Interpreter','Latex');
grid on;
box on;
for k = 2:length(x) %loop
    plot(x(k),y(k),'db');
    drawnow
end
hold off;

[KSSV]

Read about set.

[Luca Carlino]

I'm not sure I am following you.

I think you are suggesting using set to specify the figure properties, which is fine.

Once you remove the hold command, I need to force the plot function (inside the for loop) to draw on the same figure, without (a) creating a new one (default behaviour), and (b) changing the figure properties (axes, etc...), which is specifically what I am unable to do.

Could you please be a little more specific?

Answer 1

[Geoff Hayes]

Luca - use set to modify the x and y data of the plot. Replace your for loop with the following

hPlot = plot(NaN, NaN, 'db');
for k = 2:length(x) %loop
    set(hPlot, 'XData', x(k), 'YData', y(k));
    drawnow
end

On each iteration of the loop, we set (change) the x and y data to be the new position.

[Luca Carlino]

Thank you! This is exactly what I needed.