I am trying to plot variables dynamically in MATLAB. I have an array (set of states) that needs to be plotted with time. I tried plot(time,theta), where theta is a 1*5 array. With this command, I get an error saying that theta should be a scalar because time is a scalar. I then tried using for-loop to plot(time,theta(i)). The problem with this is that I get data points at discrete time intervals on my plot. However I need a continuous plot. I wonder how this can be done.
2 Answers
You need to use hold on when plotting.
For example:
time = 1;
theta = [1:100];
figure
for i=1:100
plot(time, theta(i),'r.')
hold on %--> Keeps the previous data in your plot
time = time + 1;
end
Comments
Let's see if I get this straight. Time is updated at every step, and theta are five different variables that also get updated. This should work for you:
% Use your own time variable
time = 1:100;
figure; hold on;
h = cell(5,1); % Handles of animated lines
colors = 'rgbkm'; % Colors of lines
for t = time
theta = randn(5,1);
if isempty(h{1})
% Initialize plot
for k = 1 : 5
h{k} = animatedline(t , theta(k) , 'LineStyle' , '-' , 'Color' , colors(k));
end
else
% Update plot with new data
for k = 1 : 5
addpoints(h{k}, t , theta(k));
end
end
% Update plot
drawnow
end
The object animatedline was introduced in R2014b. You can still do something similar with a conventional plot and updating the XData and YData properties of the lines at each loop.
2 Comments
user3856486
Thank you for the suggestion. However, when I tried this, it still gives me an empty plot. I am unable to see anything at all being plot.
Zep
Can you post your code? When I launch this example as-is, it plots theta as a function of time.
plot(time,theta(1:numel(time)))I guess. If not, please include a minimal executable example.timeis a single value, not an array, is that so? It is not clear what you want to do. Maybe plot the last value of theta against currenttime, while keeping the "history" of the plot?