MATLAB: How to update a plot/graph

arraygraphplotupdate

Hello everybody,

I got a plot like this one:

h = subplot(1,2,1);
plot(0, 0);
axis([-30 40 -20 100 ]);
grid on

Now I am getting a new array of x,y – points every second. How can I update the subplot h with these arrays? It is an n by 2 single array.

Thank you in advance!

Lucca

Best Answer

In your loop where you get new x,y arrays, make sure you have this line after the plot:

plot(.................
drawnow;

drawnow will force the plot to update immediately. Otherwise it probably won't get around to it until the loop is entirely finished so that all you will see is the very last set of data plotted.

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MATLAB: How to change the values of a plot inside a loop

You can set the 'xdata' and 'ydata' properties of the line. You may have to make sure you set your axis limits so they aren't reset as the data moves.

x = sort(rand(10,1));
y = rand(10,1);
h = plot(x,y);
set(gca, 'xlim', [0 20], 'ylim', [-10 1]);
n=0;
while n<5
  x=x+n;
  y=y-n;
  n=n+1;
  set(h, 'xdata', x, 'ydata', y);
  pause(1);
end

MATLAB: Text label in plot/graph

Contour example:

[X,Y] = meshgrid(-2:.2:2,-2:.2:3);
Z = X.*exp(-X.^2-Y.^2);
[C,h] = contour(X,Y,Z);
set(h,'ShowText','on','TextStep',get(h,'LevelStep')*2)
colormap cool

% Place text label

text(1.9,2.5,'Rotation: 0 Elevation: 90 Orientation: 0 Spec Range: 241.9877',...
     'Horiz','right','Vert','Bottom')

Alternatively, vertically stacked labels:

lbl  = {'Rotation', 'Elevation', 'Orientation', 'Spec Range';
        0         ,  90           0              241.9877};
cs   = sprintf('%-11s: %10.4f\n',lbl{:});
text(1.9,2.9,cs,'FontN','FixedWidth','Horiz','right','Vert','top')

Best Answer

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MATLAB: How to change the values of a plot inside a loop

MATLAB: Text label in plot/graph

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