MATLAB: Calling a callback function in GUI

callbackMATLABmatlab gui

Hello to all,

This is my first attempt to generate a GUI. Its aim is to plot the diagrams of variables (saved in .mat file as structure with time). It has to be done by choosing the name of variable from dropdwon list. Below there is a part of a code. I have 2 types of variables sorted into two seperate lists.

ana_dd = uicontrol( 'Style', 'popup',...
                    'String', ana_vars,... 
                    'Position', [20 340 100 50],...
                    'Callback', @ploting_ana);
                
misc_dd = uicontrol( 'Style', 'popup',...
                    'String', misc_vars,... 
                    'Position', [20 300 100 50],...
                    'Callback', @ploting_misc);                
    function ploting_ana(~,~)
        val=ana_dd.Value;      
        plot(T.(ana_vars{val}).time, ...
        T.(ana_vars{val}).signals.values);              
    end
    function ploting_misc(~,~)
        val=misc_dd.Value;      
        plot(T.(misc_vars{val}).time, ...
        T.(misc_vars{val}).signals.values);              
    end

As you see both ploting_ana(~,~) and ploting_misc(~,~) are pretty simmilar. There are only differences in the name of variable. I would like to ask if there is a possibility to call and define a callback function in a similar way how in regular function, so I would have sth like below. Then there won't be a need of defining two almost the same functions.

    ana_dd = uicontrol( 'Style', 'popup',...
                    'String', ana_vars,... 
                    'Position', [20 340 100 50],...
                    'Callback', @ploting(ana_vars));

Best Answer

Your problem is not taking into account the full potential of callbacks. You throw away the handle to the object you're using. Your function should look something like this. (I would also discourage the use of nested functions, as they make it harder to keep track of your variables)

function ploting_misc(hObject,~)
val=hObject.Value;

Related Solutions

MATLAB: How to use uicontrol and callback for a user-defined input flow

In the callback of popup1, you just want to modify the string in popup2.

I guess you need something like :

function popup1_callback(hObject,eventdata,handles)
Value1 = get(handles.popup1,'Value');
if Value1==1
    List = {'A';'B';'C'};
elseif Value1==2
    List = {'M';'N';'P'};
else
    List = {'X';'Y';'Z'};
end
set(handles.popup2,'String',List);

MATLAB: GUI with two popup menus

kanimbla - the way your code is structured, you don't really need to use callbacks for the popup menus since nothing is plotted until the user presses the push button. I think that you can simplify your code if you just move all logic to the push button callback plot_Callback.

Because you have written your code so that all callbacks are nested functions within the example_gui main function, any local variables defined within example_gui are accessible to the nested functions. That means handles to the widgets, the vars local variable, etc. are all available to the nested function. So you can do away with global variables and do something more like

    function plot_Callback(source,eventdata)
         % get the country id
         ctryId = get(hpopup,'Value');
         % get the attribute id
         attrId = get(gpopup,'Value');
         % get the number of countries
         numCtrs  = length(get(hpopup,'String'));
         % get the number of attributes
         numAttrs = length(get(gpopup,'String'));
         % since data the data in vars is grouped by country and by attribute
         % then we can access the appropriate data using the above information
         dataToPlot = vars((ctryId-1)*numAttrs + attrId,:);
         plot(dataToPlot);
    end

In the above, I'm assuming that the rows in the vars data is: row 1, USA GDP; row 2, USA Trade Balance; row 3, Japan GDP; and row 4, Japan Trade Balance. We access the appropriate row given the selected country (with its index in the country pop-up menu) and the selected attribute (with its index in the attribute pop-up menu).

The above should get you going. There are a couple of things to consider - try to give your local variables names that reflect more what they do. For example, instead of hpopup for the handle to the country pop-up menu, perhaps write ctryPopupHandle or something similar. As well, you can pass vars as an input to this function if you modify the signature to

 function example_gui(vars)

This way you can avoid the evalin call at

 vars=evalin('base','vars') % matrix with dimesnion 4x100

I left the pop-up menu callbacks in place but removed their code

    function popup_menu1_Callback(hObject,source,eventdata)
        % intentionally left blank

    end
    function popup_menu2_Callback(hObject,source,eventdata)
        % intentionally left blank
    end

There is no need for them to do anything (currently) since the push button callback is doing the majority/all of the work.

Try the above and see what happens!

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