How to efficiently animate plots in MATLAB? [duplicate] - matlab

Question

This question already has answers here:
How to do an animated plot in matlab
(3 answers)
Closed 4 years ago.
I wrote a simple code below for animating plots, but they tend to be rather computationally-intensive, taking entire seconds longer than intended:
function animplot(t,f,ymin,ymax,dt,num_iters)
h = plot(0,0); % set initial handle for first iteration
tic % start timer
for i=2:num_iters
delete(h);
h = plot(t,f(t-dt*i),'LineWidth',2,'color','b');
axis([min(t) max(t) ymin ymax]); pause(1/num_iters)
end
toc % end timer, return time elapsed since 'tic'
end
Replacing 1/num_iters with dT = T / num_iters, and setting T = 1, computation time for 1000 iterations is 6+ secs (rather than 1). Sample animation for t = 0:.01:2*pi; f = #(t)sin(t); dt = .05; num_iters = 1000
Any more efficient methods of animating in this manner?

Answer 1

A significantly more efficient code, adapted per solution in related inquiry:
function animplot(t,f,ymin,ymax,dt,num_iters,T)
% ANIMPLOT(t,f,ymin,ymax,dt,num_iters) -- f must be defined w/ handle,
% e.g. f = #(t)sin(t); default T = 5, num_iters = 500, dt = .05,
% (ymax - ymin) = 1.4*range.
switch nargin
case 6; T = 5;
case 5; T = 5; num_iters = 500;
case 4; T = 5; num_iters = 500; dt = .05;
case 2; T = 5; num_iters = 500; dt = .05;
ymin = 1.2*min(f(t)) - max(f(t))/5;
ymax = 1.2*max(f(t)) - min(f(t))/5;
end
dT = T/num_iters; % set pause interval
h = plot(0,0,'LineWidth',2,'color','b'); % set initial handle
set(h, 'Xdata',t, 'Ydata', f(t)); % initialize curve plot
axis([min(t) max(t) ymin ymax]);
tic % start timer
for i=2:num_iters
pause(dT)
set(h, 'Ydata', f(t-dt*i))
end
toc % end timer, return time elapsed since 'tic'
end
Note: num_iters serves primarily as animation 'resolution'; higher comes at expense of greater deviation from set T.

Answer 2

Using the command: "set(h, 'Xdata',t, 'Ydata', f(t))" will be way more efficient than reusing the plot function on every loop iteration, and may be sufficient by itself to achieve the results you are looking for. For further improvement you can enable a variable frame rate. To do this, eliminate any "pause(dt)", get the time of the current loop iteration "t", evaluate your function for that time "f(t)" and set the plot x and y data to that. This will ensure that the animation is smooth does not take any longer than specified. You can also use this technique on data sets, not just functions, by using the "interp1(x,v,xq)" function to get a linear interpolation between data points.