Index value for button group

I have a button group with 2 choices, being Low Pass and High Pass. I want to write the callback function for a button such that when I click on the button, it checks the selection of the button group. I tried to use this but it does not work and says unrecognised function or variable 'value'

% Button pushed function: STARTButton
        function STARTButtonPushed(app, event)
            selection = app.FilterTypeButtonGroup.SelectedObject;

            if selection == 'Low Pass'
                value = 1;
            elseif selection == 'High Pass'
                value = 2;
            end

            app.SelectionEditField.Value = value;
        end

Answer 1

[Walter Roberson]

https://www.mathworks.com/help/matlab/ref/uibuttongroup.html#mw_64460ebb-84cc-4b21-8e3c-1da7ae15c44d

SelectedObject for a uibuttongroup is the handle of the button, not its label.

A button group is not a single object that happens to display multiple buttons. A button group is a collection of buttons, each of which can have its own behavior and label and position controls and whatever.

[Ye Ken Kok]

So if I want to give each button like an index number, what should I do?

[Walter Roberson]

You could set UserData for each button. Or you could set the tag for each button.

Of you could set the String property for each button, after which you could do

selection = app.FilterTypeButtonGroup.SelectedObject.String;

and then you would not need an index for them.