Plotting multiple data sets on the same polaraxes in AppDesigner

Should I be able to plot 2 or more data sets - e.g., measured and interpolated points - in the same polaraxes ?

I can do this in a plain figure, or GUIDE, using "hold on" and returning a handle from each plot, but I'm not succeeding in AppDesigner(2021b), which I'd like to use because of its clean appearance, ease of use and WYSIWIG screen captures using exportapp.

I'm working from the on-line example:

openExample('matlab/AppdPolarExample')

https://uk.mathworks.com/help/matlab/creating_guis/polar-plotting-app-gui-in-app-designer.html

The code below fails where "plotmark" is defined:

          % Define theta. Get a and b
            theta = double(0:360)*(pi/180.0);
            steps = double(0:10:360)*(pi/180.0);    % My new code
            a = app.aEditField.Value;
            b = app.bEditField.Value;
            
            % Calculate r and plot it
            r = (1 + sin(a.*theta)).^(1/b);
            s = (1 + sin(a.*steps)).^(1/b);         % Also here
            plotline = polarplot(app.Pax, theta, r);
            plotmark = polarplot(app.Pax, steps, s, 'o', ...
                                'MarkerFaceColor', 'r', 'MarkerEdgeColor', 'k'); % THE ERROR IS HERE
            
            % Set line color
            plotline.Color = app.DropDown.Value;
            plotline.LineWidth = 1.5;

The error message is "invalid or deleted object".

Are multiple plots impossible here, or is there a work-around ?

Answer 1

[Kevin Holly]

You can still use hold on in App Designer, but you have to specify the axes.

    properties (Access = private)
        Pax % Polar axes
    end  

    methods (Access = private)
        
        function updateplot(app)
            
            % Define theta. Get a and b
            theta = 0:pi/1800:2*pi;
             steps = double(0:10:360)*(pi/180.0);    % My new code
            a = app.aEditField.Value;
            b = app.bEditField.Value;
            
            % Calculate r and plot it
            r = (1 + sin(a.*theta)).^(1/b);
             s = (1 + sin(a.*steps)).^(1/b);         % Also here
            plotline = polarplot(app.Pax, theta, r);
            hold(app.Pax,"on")            
            plotmark = polarplot(app.Pax, steps, s, 'o', ...
                                'MarkerFaceColor', 'r', 'MarkerEdgeColor', 'k');
            
            % Set line color
            plotline.Color = app.DropDown.Value;
            plotline.LineWidth = 1.5;
        end
    end

[Pawel Tokarczuk]

Thanks, that was certainly one issue - without that, stray figures just kept popping up from nowhere.

Also, I needed to populate the app with a lot of properties that wouldn't just be local to the start-up function.

After that, I was able to create my graphs once, then update the RData of each plot to modify the curves in response to parameter changes.

I'm getting used to the operation of AppDesigner now, so thanks for your help. Call this resolved.

[Rik]

Comment posted as flag by Dominique:

a pain solver ! Thank you.