How to make the live plot run in seconds?

Hello,

Can somebody please help me debug this code? I'm using a EEG data where records eye blink happens every 3 seconds. And I want to plot this in real time (second). But when I use code

drawnow limitrate

The plots seems faster than I expect. I also try 'drawnow', which gives me really slow drawing.

%Plot two channels without filters
clear
clc
close all

h = figure;
%a1 = animatedline('Color',[0 .7 .7]);


axis tight
%Sampling Frequency = 250
fs = 250;
opts = detectImportOptions("blink.txt");
%opts.VariableNamesLine = 1;
C = readtable('blink.txt');

A = table2array(C(:,23));
t = (1:height(C))/fs;

%Create subplot
sph1 = subplot(2,1,1);
axis([0 10 -18000 0]);
a1 = animatedline('Color',[0 1 1]);
xlabel('time in seconds');
ylabel('uV');
title('EEG signals in channel 1');

sph2 = subplot(2,1,2);
axis([0 10 0 18000]);
a2 = animatedline('Color',[0 1 1]);
xlabel('time in seconds');
ylabel('uV');
linkaxes([sph1,sph2],'x');

for k = 1:height(C)
    %Guard addpoints call with check
    
    
    addpoints(a1,t(k),C.EXGChannel1(k));

    hold on
    addpoints(a2,t(k),C.EXGChannel6(k));

    
    %For scrolling window
    xlim([max(0,t(k)-30) max(30,t(k))]);
    %ylim('auto');
    %xlimit = [t(k)-30,t(k)];
    %set(a1,'xlim',xlimit);
    %set([a1,a2],'xlim',xlimit);
    drawnow limitrate
    
   
end

I appreciate a lot for your help!

[Walter Roberson]

Do not call hold on inside the loop. You are not adding any new graphics objects inside the loop.

Your animated lines are in two different subplots, but you are only adjusting the limit on one of them. You do link the 'x' properties, but you do not link the XLim properties.

[LuYao Guo]

Hi Walter, thank you for suggestions. I've edited the part based on your suggestions but the speed of plotting is not changing at all. Do you have more ideas about this? Thank you.

Answer 1

[Dongyue]

Hi LuYao, you can try to use pause(1) in your loop, which can stop the iteration for 1 second each turn. For more details, please go through the link below:

https://www.mathworks.com/help/matlab/ref/pause.html