How to get the point under mouse click on the plot or histogram?

Question

Hakob Bazoyan 2019-8-18

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编辑： Adam Danz 2019-8-18

I have an axis object in my application, and I am drawing histogram on that axis object.

Is there any event fired when I click a bar on that histogram? If yes How can I intercept that event and get the index of the bar under mouse position?

This is not about the script where I can use 'waitforbuttonpress' this is application where I have nowhere to use any wait function without blocking the application.

Thanks, in Advance.

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Answer 1

Adam Danz 2019-8-18

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https://ww2.mathworks.cn/matlabcentral/answers/476609-how-to-get-the-point-under-mouse-click-on-the-plot-or-histogram#answer_388094

编辑：Adam Danz 2019-8-18

在 MATLAB Online 中打开

You can use the ButtonDownFcn function. Here's a demo you can run. It prints the selected bar index to the command window.

figure(); 
h = histogram(randn(10)); 
h.ButtonDownFcn = @clickHistFcn; 
function clickHistFcn(hObj,event)
% Get the bar edges and click coordinate
edges = hObj.BinEdges; 
click = event.IntersectionPoint; 
% Determine which bar was clicked
barIdx = find(click(1) >= edges, 1, 'last');
% Do whatever you want with that....
fprintf('bar %d selected.\n',barIdx)
end

Note, this code above does not ignore empty bar bins. For example, try it with these data.

h = histogram([rand(1,20),rand(1,20)+5],10)

If you'd like to ignore empty bars,

function clickHistFcn(hObj,event)
% Get the bar edges and click coordinate
edges = hObj.BinEdges; 
values = hObj.Values;
edges([false,values==0]) = [];  %remove edges that contain empty bars
click = event.IntersectionPoint; 
% Determine which bar was clicked
barIdx = find(click(1) >= edges, 1, 'last');
fprintf('bar %d selected.\n',barIdx)
end

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Hakob Bazoyan 2019-8-18

Thanks a lot Adam,, this seems to answer my question

Adam Danz 2019-8-18

Great! If you plan to return information about the bar plot, you can get that info from the 'hObj' handle which is the first input to the buttondown function.

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