Animate a rectangle, for loop used

Hello! The code below takes a large matrix (x) and shows 'o' moving up and down on a plot. I would like to change the 'o' into a rectangle moving in the same way, hanging by a string. How would I do this?

for i = 1:125

plot(x(i),'o')

axis([0 5 -5 5])

y(i) = getframe

end

movie(y,25,25)

[Anastasia Zistatsis]

supposed to look like this: https://www.youtube.com/watch?v=05RekjbFung&feature=youtu.be

Answer 1

[Image Analyst]

Use the rectangle() function. Get it's handle so you can delete the old one when you want to place a new one.

[Anastasia Zistatsis]

Thank you! I'm not sure how to use it. I'm trying to call it

r = rectangle('Position', [0.5 1.5 y1 y2]);

and then putting that in the plot(). My y values will be changing, how do I go about that?

[Image Analyst]

Anastasia, see this little animation demo.

% Initialization steps.
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 13;
% Define oscillation parameters.
period = 10;
t = linspace(0, 5 * pi, 100);
y = 30 * sin(2 * pi * t / period);
% Define graphics parameters:
rectangleHeight = 10;
rectangleWidth = 10;
rectangleX1 = 10;
lineX = 15;
% Set up axes.
grid on;
ylim([-50, 50]);
xlim([0, 30]);
xlabel('X', 'FontSize', 15);
ylabel('Y', 'FontSize', 15);
% Start the movement:
for k = 1 : length(y)
	caption = sprintf('Iteration %d, y(%d) = %f', k, k, y(k));
	fprintf('%s\n', caption);
	% Place a rectangle at the current y location.
	r = rectangle('Position', [rectangleX1, y(k), rectangleWidth, rectangleHeight], 'FaceColor', 'r');
	title(caption, 'FontSize', 15);
	% Drawline from to to top of rectangle.
	hLine = line([lineX, lineX], [50, y(k)+rectangleHeight], 'LineWidth', 5, 'Color', 'b');
	drawnow;
	% Wait long enough to see it at this location.
	pause(0.1)
	% Delete the rectangle to prepare for the next one.
	if k < length(y) % Don't delete the very last one.
		delete(r);
		delete(hLine);
	end
end