Drawing a rectangle over existing plot
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gummiyummi
on 28 Jul 2020
Answered: Vahidreza Jahanmard
on 14 Nov 2023
I have a subplot in Matlab with two plots. (first picture) I want to draw boxes as seen in the second picture, for specific xvalue ranges. I tried annotation however it does not span all plots. Anybody able to help me?
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/338020/image.png)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/338023/image.png)
3 Comments
Adam Danz
on 31 Jul 2020
Edited: Adam Danz
on 4 Aug 2020
That's a clearer problem; and a tough one.
The annotation function has been around for a long time and many people have requested that the function accept location values in data-units rather than normalized figure units. Obviously these wishes have never been granted.
See answer for a cleaner solution.
Accepted Answer
Adam Danz
on 31 Jul 2020
Edited: Adam Danz
on 3 Aug 2020
To use an annotation object in the way you're describing, you'd need to convert the data units, which are relative to the axes, to normalized figure units. Though this is possible, it often leads to headaches since a bunch of minor details turn out to be important such as setting axis limit and figure resizing.
The cleaner approach is to highlight the sections within the axes using the original data units.
Here's a demo that you can apply to your project.
% Set up a figure with two subplots and identical x-axes
figure()
sp(1) = subplot(2,1,1);
x = 0:10:1400;
y = randi(400,size(x))+200;
plot(x, y, '.')
xlim([0,1400])
ylim([200,600])
sp(2) = subplot(2,1,2);
y2 = rand(size(x))*5-1;
plot(x,y2,'.')
linkaxes(sp, 'x') % Link the x axes
ylim([-1,4])
% Define rectangle center and +/-d
rectCnt = 590;
rectDelta = 25; % +/-25 from center
% Draw rectangle in upper axes
rectX = rectCnt + rectDelta*[-1,1];
rectY = ylim([sp(1)]);
pch1 = patch(sp(1), rectX([1,2,2,1]), rectY([1 1 2 2]), 'r', ...
'EdgeColor', 'none', 'FaceAlpha', 0.3); % FaceAlpha controls transparency
% Copy rectangle to 2nd axes and adjust y limits
pch2 = copyobj(pch1, sp(2));
rectY2 = ylim(sp(2));
pch2.YData = rectY2([1 1 2 2]);
If you plan on moving the rectangles around, you can link their XData properties so you only need to change one of them and the other one will follow.
linkprop([pch1, pch2], 'XData')
% now slide the bar to the right by 100 units
% and see what happens...
pch1.XData = pch1.XData + 100;
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/339892/image.png)
15 Comments
Afiq Azaibi
on 17 Mar 2023
Edited: Afiq Azaibi
on 17 Mar 2023
% Set up a figure with two subplots and identical x-axes
figure()
sp(1) = subplot(2,1,1);
x = 0:10:1400;
y = randi(400,size(x))+200;
plot(x, y, '.')
xlim([0,1400])
ylim([200,600])
sp(2) = subplot(2,1,2);
y2 = rand(size(x))*5-1;
plot(x,y2,'.')
linkaxes(sp, 'x') % Link the x axes
ylim([-1,4]);
xregion(sp(1), 565, 615, 'FaceColor', 'r');
xregion(sp(2), 565, 615, 'FaceColor', 'r');
You can also set the EdgeColor properties to emphasize the edges but the default EdgeColor is 'none'.
More Answers (1)
Vahidreza Jahanmard
on 14 Nov 2023
To plot the rectangles, you can use this:
% do all your plots
annotation('rectangle',[x y w h]);
for x, y, w, and h, you can plot one time and set the place of the rectangle manually and copy the position to your code
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