Obtain data points from plot using 'buttondownfcn' nested functions

function [Xsig,Ysig] = GetPoint(Figure)
set(Figure,'ButtonDownFcn', @ExtractPoint) ;
    function ExtractPoint(ClickedPoint,~)
        waitforbuttonpress ;
        Xsig = get(ClickedPoint,'XData') ;
        Ysig = get(ClickedPoint,'YData') ;
    end
end

I have a plot created in 'Figure'. I would like to be able to select a variety of points on the curve and export the coordinates into the workspace. I have seen people use ginput and datacursor mode in other forums but neither of these methods work since I have a 2 subplots.

Any help is appreciated. Thank you!

Answer 1

[darova]

Here is an example

function main
x = rand(100,1);                       % generate random data
y = rand(100,1);
h = plot(x,y,'.r');                    % plot data
set([h gcf],'hittest','off')           % turn off hittest 
set(gca,'buttondownfcn',@func)         % assign function to gca
    function func(hobj,~)
        p  = get(hobj,'currentpoint'); % get coordinates of click
        d = pdist2([x y],p([1 3]));    % find combination of distances
        [~,ix] = min(d);               % find smallest distance
        line(x(ix),y(ix),'linestyle','none','marker','o')
        [x(ix),y(ix)]
    end
end

[Andres Elzaurdia]

Thank you for this! It's starting to make sense. I assume that lines '% find combination of distances' and '% find smallest distance' are performing calculations for a different problem than just obtaining the point coordinates correct?

Also, this function is in my script at the bottom and I would like to pass the 'p' variable into my script workspace. main should have access to 'p', so how do I make it so that when I call main in my script, it outputs variable 'p'?

p = main() ;

[darova]

• I assume that lines '% find combination of distances' and '% find smallest distance' are performing calculations f

Yes, correct

• my script workspace. main should have access to 'p'

just declare p variable outside the function

[Andres Elzaurdia]

darova, I think you misinterpreted my question. main is a local function in my script. main is called by a callbackfcn. I would like to pass variable p from my callbackfcn main into my script workspace. I defined p = 0 in my script but it still does not get passed to my workspace. How can I solve this problem other than using globals?

[darova]

Try to pass data into UserData property

set(gca,'userdata',num2str(p))      % add this line insdie the function

To get data back

get(gca,'userdata')
% get(gca)

[Ahmed]

Hello everyone,

I'm also struggling with this. Where should the function (func) be placed in the code view? I have the similar implementation but my click function doesnt seem to be triggered when I click on the plot. I think the reason is becuase it is in another slider function. So I'm not sure now where to place in my click function in the code view.

% Value changed function: FrequencySlider

function FrequencySliderValueChanged(app, event)

value = app.FrequencySlider.Value;

freq=value;

[d,ix]=min(abs(app.freq_vec-freq));

scatter3(app.UIAxes,app.XYZ(:,1)*10000,app.XYZ(:,2)*10000,abs(app.y(:,ix))*10000,[],abs(app.y(:,ix))*10000,'filled','ButtonDownFcn',@click)

view(app.UIAxes, [0 90]);

c = colorbar(app.UIAxes)

colormap(app.UIAxes, jet)

axis(app.UIAxes, 'tight')

axis(app.UIAxes, 'equal')

app.EditField.Value=value;

function click(~,eventData)

coords = eventData.IntersectionPoint;

app.ZEditField.Value=coords;

end

end