How can I get the position of a datapoint on a plot?

Question

Pal Szabo 2017-9-21

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/357777-how-can-i-get-the-position-of-a-datapoint-on-a-plot

评论： Pal Szabo 2017-9-22

I have the following code:

 x=[1:1:5]
 a=rand*10
 y=[2,a,3,5,4]
 set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0 1 1]);
 plot(x,y)
 hold on
 plot(2,a,'.','markersize',40) 
 % Create and display the text label
 url = 'cam.ac.uk';
 labelStr = ['<html><a href="">' 'SPEC' '</a></html>'];
 jLabel = javaObjectEDT('javax.swing.JLabel', labelStr); 
 [hjLabel,hContainer] = javacomponent(jLabel, [1000,800,30,20], gcf);
 % WHAT SHOULD [1000, 800, 30, 20] BE IF I WANT THE LABEL TO BE AT THE SAME
 % POSITION AS THE DOT ON THE PLOT?
 % Modify the mouse cursor when hovering on the label
 hjLabel.setCursor(java.awt.Cursor.getPredefinedCursor(java.awt.Cursor.HAND_CURSOR));
 % Set the label's tooltip
 hjLabel.setToolTipText(['Visit the ' url ' website']);
 % Set the mouse-click callback
 set(hjLabel, 'MouseClickedCallback', @(h,e)web(['http://' url], '-browser'))

How can I get the position of the point which is plotted randomly? Now it looks like this:

I want the "SPEC" hyperlink to appear just next to the randomly plotted point. How can I do that?

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Answer 1

Robert U 2017-9-22

1
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https://ww2.mathworks.cn/matlabcentral/answers/357777-how-can-i-get-the-position-of-a-datapoint-on-a-plot#answer_282672

在 MATLAB Online 中打开

Hi Pal Szabo,

that should do what you desired:

 x=[1:1:5];
 a=rand*10;
 y=[2,a,3,5,4];
 set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0 1 1]);
 plot(x,y)
 hold on
 plot(2,a,'.','markersize',40) 
 % Create and display the text label
 url = 'cam.ac.uk';
 labelStr = ['<html><a href="">' 'SPEC' '</a></html>'];
 jLabel = javaObjectEDT('javax.swing.JLabel', labelStr); 
 % Adjust label position
 ah = gca;
 set(ah,'Units','pixels')
 axesPos = get(ah,'Position');
 drawnow();     % necessary to fix the axes positions
 Px = round(ah.Position(1) + ah.Position(3)*(2-ah.XLim(1))/(ah.XLim(2)-ah.XLim(1))); % x-position is alway 2
 Py = round(ah.Position(2) + ah.Position(4)*(a-ah.YLim(1))/(ah.YLim(2)-ah.YLim(1)));
 [hjLabel,hContainer] = javacomponent(jLabel, [Px-30/2,Py+10,30,20], gcf);     % center for x, move 5px above y
 set(ah,'Units','normalized')
 % Modify the mouse cursor when hovering on the label
 hjLabel.setCursor(java.awt.Cursor.getPredefinedCursor(java.awt.Cursor.HAND_CURSOR));
 % Set the label's tooltip
 hjLabel.setToolTipText(['Visit the ' url ' website']);
 % Set the mouse-click callback
 set(hjLabel, 'MouseClickedCallback', @(h,e)web(['http://' url], '-browser'))