Vector as ItemsData property in List Box

Hi all,

im coding a fairly easy app with app designer and im struggling with the input/output for List Box property "ItemsData".

What i want to do is to show the user 2 options ("Items") in a list-box. These options then lead to vectors of 2 numbers ("ItemsData"). Lets say:

With ItemsData(Option 1) = [2950 3350] and ItemsData(Option 2) = [3600 4500]

Now i want to use these 2 integers in my main function and i cant figure out how to do the indexing right. I tried using a cell array as ItemsData with combined indexing:

A = B{1,1}(1,1)

which leeds to an error because of the curly brackets.

If it is any easier with a Switch or DropDown its fine too! There are just 2 options.

Thanks for any help on this!

Answer 1

[Oskar Kilgus]

I found a way to do it (If anyone is having trouble with this issue in the future)

1) List-Box ItemsData as 1x2 numeric vector:

[1 2]

2) value-changed function callback:

% Value changed function: choosefromListBox
        function choosefromListBoxValueChanged(app, event)
            app.whatever = str2num(app.choosefromListBox.Value)
        end

3) reference in other function:

app.whatever(1,1) %returns 1

______________________________

Thanks @Simon Chan for your effort!

Answer 2

[Simon Chan]

Suppose the listbox is defined as follows and ItemsData are given in your example.

app.ListBox = uilistbox(app.UIFigure);

You may get the data directly via the following:

A = app.ListBox.Value

[Oskar Kilgus]

Thanks for the reply Simon!

In that case A would be a 1x2-numeric vector like [2950 3350] or [3600 4500] right?

The problem is to now refer to eg. the value 2950 in another function in the app.

Can you help me with this?

[Simon Chan]

Try this:

A = app.ListBox.Value(1)

[Oskar Kilgus]

it then says "'Value' must be a double scalar within the range of 'Limits'."

[Simon Chan]

I think you use the value 2950 in another function which requires a lower and upper limit as well.

So you need to define the limits before you use this value on another function. Or the limits you already defined does not cover the value '2950' and hence it gives the above mentioned error.

Could you please let me know the function you are going to use the value '2950'?

[Oskar Kilgus]

 % Button pushed function: StartButton
        function StartButtonPushed(app, event)
            fs = 48000;
            adr = audioDeviceReader(fs);
            buff = dsp.AsyncBuffer(Capacity = fs*3);
            

            numIterations = floor(450*fs/adr.SamplesPerFrame);
            o=1;
            
            for index=1:numIterations
                frame = adr();
                write(buff,frame);

                if buff.NumUnreadSamples >= 2*fs
                    o=o+1;
                    data = read(buff);
                    
                    [psp, f] = pspectrum(data,fs);
            
                    f_index = find(f >= app.choosefromListBox.Value(1) & f <= app.choosefromListBox.Value(2));
                    
                    p = 10*log10(psp(f_index));
                    m(o,:) = mean(p)
                end
            end
        end

f_index is supposed to find f values above the first vector entry (eg. 2950) and below the second entry (eg.3350). So this is where i want to refer to the listbox itemsdata.

[Oskar Kilgus]

oh and this is the value changed function (so u get the syntax):

        % Value changed function: choosefromListBox
        function choosefromListBoxValueChanged(app, event)
            app.FreqRange = app.choosefromListBox.Value
        end

[Simon Chan]

Could you please check whether the following lines gives the correct values to you or not?

app.choosefromListBox.Value(1)      % gives 2950 to another function
app.choosefromListBox.Value(2)      % gives 3350 to another function

[Oskar Kilgus]

I tried exactly that (see the code i supplied) and it resulted in the error

"'Value' must be a double scalar within the range of 'Limits'."

The interesting value at the end of the function is m(o,:) = mean(p). I tried it again and now i end up with m=[0; NaN]. For the next iteration i still end up with the error message above!