Normalize axis scale for annotations

Question

HC98 2024-2-28

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2088071-normalize-axis-scale-for-annotations

评论： Dyuman Joshi 2024-2-29

I want to label a simple plot for some notes:

hf = figure;
x = -180:180; 
f = @(x) 0.09*sech(-x/18);
plot(x, f(x));
ha = annotation('arrow');
ha.Parent = hf.CurrentAxes;  % associate annotation with current axes
% now you can use data units
ha.Y = [50 20];
ha.X = [f(20) f(20)];
annotation("doublearrow", [0.45 0.45], [0.1 1]); 

The trouble is, I want to use the coordinates from the plot, not the "normalized" figure coordinates. How can I rescale them so that

annotation("doublearrow", [0.45 0.45], [0.1 1]);

becomes

annotation("doublearrow", [0 0], [0 1]);

Thanks

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Dyuman Joshi 2024-2-29

You can use rescale on the values and then provide them as input to annotation().

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Answer 1

Austin M. Weber 2024-2-28

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https://ww2.mathworks.cn/matlabcentral/answers/2088071-normalize-axis-scale-for-annotations#answer_1418211

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The text function allows you to place annotations on a figure using axes coordinates. For example:

hf = figure;

x = -180:180;

f = @(x) 0.09*sech(-x/18);

plot(x, f(x));

ha = annotation('arrow');

ha.Parent = hf.CurrentAxes; % associate annotation with current axes

% now you can use data units

ha.Y = [50 20];

ha.X = [f(20) f(20)];

% Add annotations

hold on

text(0,0.08,'⇑','FontSize',20,...

'HorizontalAlignment','center') % Other double arrows: ⇐ ⇑ ⇒ ⇓

hold off

I'm sure there is a way that you can use the annotation function to do what you want, but I think this method might be easier. I would have to play around with annotation to see how it might work.