Can't switch between the contents of two different ListBoxes

I need to create a GUI with Matlab App Designer. I'm processing EEG-Data. After loading the Data into the first ListBox called SignalListBox I can plot or filter the data. After filtering, I save the filtered data as a new Workspace and load it into a second ListBox called ListBox. Following that, I'd like to be able to change between the ListBoxes. So far, I can only use the data of SignalListBox and not switch, once I have created the second ListBox with filtered data.

This is the code for the both boxes,

properties (Access = private)
      % other variables I've used
        useFilteredData = false;
end
    function SignalListBoxValueChanged(app, event)
        value = app.SignalListBox.Value;
       
        if app.useFilteredData 
            value = app.ListBox.Value;
        else
            value = app.SignalListBox.Value;
            app.ws = 'Paradigma 2';
        end
    end
    
    % Value changed function: ListBox
    function ListBoxValueChanged(app, event)
        value = app.ListBox.Value;
        if app.useFilteredData  
            value = app.ListBox.Value;
            app.ws_filt = 'Paradigma 2 gefiltert';
        else
            value = app.SignalListBox.Value;
        end
        
    end    

% Button pushed function: plotButton
        function plotButtonPushed(app, event)
             if app.useFilteredData 
                app.t = app.t_f;
                app.zeit = app.zeit_filt;
                app.f = app.f_f;
                app.freq = app.freq_filt;
            else
                app.t = app.t;
                app.zeit = app.zeit;
                app.f = app.f;
                app.freq = app.freq;
            end
            
            if app.FPzCheckBox.Value
                plot(app.UIAxes, app.t, app.zeit(:,1));
                plot(app.UIAxes2, app.f, abs(app.freq(:,1)));
                
                hold(app.UIAxes, 'on');
                hold(app.UIAxes2, 'on');
            end
    % plot directions for other checkboxes
        end 
        

in my filter function, I set the useFilteredData variable to true

    function FilterButtonPushed(app, event)
    % filtering the data... 
    
        save('/Users/mina/Desktop/App/app_p2_filt.mat','zeit_filt','freq_filt','t_f','f_f')
            app.ws_filt = load('App/app_p2_filt.mat');
            
            app.ListBox.Items = {'Paradigma 2 gefiltert'};
            app.ListBox.ItemsData = app.ws_filt;
            app.ListBox.Enable = true;
            app.ListBox.Visible = 'on';
            app.useFilteredData = true;
    end
    

The error I get is 'Index in position 2 exceeds array bounds.' referring to the first plot() line. I've checked and I can plot both filtered and unfiltered data from the workspace using: plot(t_f,zeit_filt(:,1)); So I suppose theres something wrong when switching the bool variable, but I can't figure out what.

[Jon]

It is hard to debug just from reading through the code. Could you create a self contained runnable example that demonstrates the problem and please attach it?

[Mina Westphal]

I've attached the workspace and the app. I hope thats what you meant. If not, let me know.

[Jon]

OK, now I can begin to look at your code, but because, I'm not familiar with the specifics of your application, and it is not in English, I'm not sure how to use your user interface. Can you please list the steps to take to reproduce your problem.

[Mina Westphal]

Of course, sorry. First you click "laden" to load the workspace. Then you select Paradigma 2. Where it says "Wende einen Bandpass-Filter an" you have the options to put in the lower and upper Frequency you want the signal Paradigma 2 to be filtered by. Then you click "filter" and the second ListBox with "Paradigma 2 gefiltert" should appear. Then you select that new "Paradigma 2 gefiltert" and choose one or all of the channels under "Kanäle" you want to see plotted. And then when you click on the "plot" button you should get the same error that I did.

Answer 1

[Cris LaPierre]

I think the issue is that you have loaded your filtered data to the structure app.ws_filt, yet in your plotting code, you are treating the data as if it were loaded to app.

I think you need to keep your load comand the same, which means you need to update the if statement at the top of your Plot callback to load the filtered data from app.ws_filt

if app.useFilteredData 
    app.t = app.ws_filt.t_f;
    app.zeit = app.ws_filt.zeit_filt;
    app.f = app.ws_filt.f_f;
    app.freq = app.ws_filt.freq_filt;

[Mina Westphal]

Thank you, I tried your suggestion but now it says 'Dot indexing is not supported for variables of this type.'

[Cris LaPierre]

Worked for me. I made that change in the app you have shared. Please share the line of code that is throwing that error.

[Jon]

In addition to @Cris LaPierre correction, you must also modify the code below, commenting out your assignment of the string 'Paradigma 2 gefiltert' to app.ws_filt. If you don't do this you wipe out all of the data that you loaded in app.ws_filt

Also this callback then actually does nothing. So selecting the second list box, which calls this function doesn't do anything, but apparently it is not needed, as the code will run.

Probably @Cris LaPierre never clicked on that box so this function wasn't called. That's why the code ran for him

        % Value changed function: ListBox
        function ListBoxValueChanged(app, event)
            value = app.ListBox.Value;
            if app.useFilteredData  
                value = app.ListBox.Value;
                % % % app.ws_filt = 'Paradigma 2 gefiltert'; %****
            else
                value = app.SignalListBox.Value;
            end
                
        end

[Mina Westphal]

Thank you to both of you. Now it's working as intended.