Placing annotations at specific xy coordinates

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Vance Blake
Vance Blake 2019-9-13
评论： DGM 2025-4-22
Just wondering but I wanted to put annotations/text boxes at specific coordinates but when I read up on the page I saw that the values of x and y in the 'dim' vector must be between 0 and 1. Im just looking for a way to place 'X's at specific xy coordinates to signify that those points are no longer being considered for my calculations?? I figured annotations would be good way to accomplish that because I wanted to avoid matlab cconsidering a plotted X as an active point and therefore valid for my calculations. If you have any work arounds or suggestions Im all ears. Thanks for the help

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Adam Danz
Adam Danz 2019-9-13
编辑：Adam Danz 2025-4-21
Annotation objects are designed to annotation the figure space in figure coordinates. They are not designed to be positioned within axes coordinates. For axes and data coordinates, using axes objects such as rectangle or text.
hold on
plot(x,y,'rx')
If you wanted rectangles for whatever reason,
widthHeight = [.1,.1];
rectangle('Position', [x-widthHeight(1)/2, y-widthHeight(2)/2, widthHeight])
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Vance Blake
Vance Blake 2019-10-16
Hey Adam how are you ? Its been a while but I have some more questions that I would really like your help with when you get the chance the link to the question is below. https://www.mathworks.com/matlabcentral/answers/485730-define-an-if-statement-based-on-on-finding-duplicate-values-between-arrays-and-then-rewrite-code-to

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更多回答（4 个）

Olle Trollberg
Olle Trollberg 2023-8-29
I recently ran into this and here is a simple way to get around it using some anonymous functions to do rescaling.
Works at least in 2022b
plot(x,y) % Create whatever plot
ax = gca;
% Define helper funcitons to normalize from axis coordinates to normalized position in figure.
xnorm = @(x)((x-ax.XLim(1))./(ax.XLim(2)-ax.XLim(1))).*ax.InnerPosition(3)+ax.InnerPosition(1)
ynorm = @(y)((y-ax.YLim(1))./(ax.YLim(2)-ax.YLim(1))).*ax.InnerPosition(4)+ax.InnerPosition(2)
annotation('textarrow',xnorm(x_in_axis_coordinates),ynorm(y_in_axis_coordinates),'string','Arrow Text');
Image Analyst
Image Analyst 2019-9-13
No, not true. If you want to place annotation text onto a plot you can use text() using the x,y that's used for that plot, whatever range it might have, which can be more than 1.
Have you tried
badIndexes = .......whatever you need to do to identify "points are no longer being considered for my calculations"
hold on
plot(x(badIndexes), y(badIndexes), 'rx', 'MarkerSize', 15, 'LineWidth', 2) % Overlay big red X's
Bruno Luong
Bruno Luong 2019-9-14
There are several tool on File Exchange, such as this one
Dmitrij Usov
Dmitrij Usov 2025-4-16
f = figure;
an = annotation('arrow');
an.Parent = f.CurrentAxes;
an.X = [0 1];
an.Y = [0 1];
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Adam Danz
Adam Danz 2025-4-21
Ran in:
Also watch out for axes direction.
Note that assigning axes to the annotation's parent is undocumented.
% some fake data to plot
x = linspace(0,1.5,100);
plot(x,x.^2); hold on
plot(x,sqrt(x))
xlim([0 1.5])
ylim([0 1.5])
set(gca,'YDir','Reverse') % <-------------------Added
% a text box hanging out of the axes
an1 = annotation('textbox');
an1.Parent = gca;
an1.String = 'the curves cross here';
an1.HorizontalAlignment = 'center';
an1.VerticalAlignment = 'middle';
an1.Position = [1.1 0.95 0.6 0.08];
an1.BackgroundColor = [1 1 0];
% a text arrow doing the same
an2 = annotation('textarrow');
an2.Parent = gca;
an2.String = 'the curves cross here';
an2.HorizontalAlignment = 'left';
an2.VerticalAlignment = 'top';
an2.X = [1.15 1];
an2.Y = [0.8 1];
% another arrow pointing to something beyond ylim
an3 = annotation('textarrow');
an3.Parent = gca;
an3.String = 'this line keeps going';
an3.HorizontalAlignment = 'center';
an3.VerticalAlignment = 'top';
an3.X = [0.5 1.5];
an3.Y = [1.1 1.5^2];
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