MATLAB: How do i select a point on matlab UIaxes and then get data for it

app designerappdesignerbrushbrush toolrbboxselect datauiaxesuifigure

I have a plot on UIAxes and i want to use the brush tool to select the already plotted data and get what points the user selects

Best Answer

The brush tool is not (yet?) available on UIAxes as of r2019b; neither is rbbox. Update: the brush tool is now available as of r2020a.
Here's a workaround for releases <= r2019b.
The first block of code simulates an App by creating a plot on a UIAxes within a UIFigure.
The second block of code is a function that can be added to your App. When the function is called, the title of the axes will change to instructions for the user to draw a rectangle with their mouse. After drawing the rectangle, it will disappear and the (x,y) coordinates within or on the border of the rectangle will be returned.
See inline comments for details. 
% Create a demo-app
app.myApp = uifigure(); 
app.UIAxes = uiaxes(app.myApp); 
plot(app.UIAxes, rand(10,4),'o')
title(app.UIAxes, 'My Data')
% Call the custom function so the user can 
% draw a temporary rectangle within the axes. 
[x,y] = selectDatapoints(app.UIAxes);
function [x,y] = selectDatapoints(ax)
    % Remove any pre-existing rectanlges (if any)
    delete(findall(ax, 'Type',  'images.roi.Rectangle'))
    
    % Get coordinates of all data points in the axes
    xyobj = findall(ax.Children, '-Property','xData'); 
    xydata = get(xyobj, {'XData','YData'});
    xydataMat = cell2mat(xydata'); 
    
    % change title of axes to instructions, in red
    originalTitle = get(ax.Title, {'String', 'Color'}); 
    set(ax.Title, 'String', 'Draw rectangle around desired datapoints', 'Color', 'r')
    % allow user to draw rectangle; see more options:
    % https://www.mathworks.com/help/images/ref/drawrectangle.html
    pan(ax, 'off') %turn off panning so the interaction doesn't drag the data.
    roi = drawrectangle(ax); 
    
    % quit if figure is closed
    if ~isvalid(roi)
       x = []; 
       y = []; 
       return
    end
    
    % Return original title
    set(ax.Title, 'String', originalTitle{1}, 'Color', originalTitle{2})
    
    % determine which coordinates are within the ROI
    isIn = xydataMat(1,:) >= roi.Position(1) & xydataMat(1,:) <= sum(roi.Position([1,3])) ...
        & xydataMat(2,:) >= roi.Position(2) & xydataMat(2,:) <= sum(roi.Position([2,4])); 
    
    % Delete ROI
    delete(roi)
    
    % Return outputs
    x = xydataMat(1,isIn); 
    y = xydataMat(2,isIn);    
end
Related Question