Values of selected item in list box moved into a struct

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Nwasinachi 2022-11-22

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https://ww2.mathworks.cn/matlabcentral/answers/1859968-values-of-selected-item-in-list-box-moved-into-a-struct

编辑： Nwasinachi 2022-11-29

i have created an empty struct, how do i move the values of the selections made in a list box into a struct. Usually this is created in matrix in matlab when you run the code in the command window, but for app designer is seems different.

I have attached a the code generated from App designer for one of my list box.

How do i make the current selection or what even selection made appear in an already created struct. i have also include the code for the empty struct.

 properties (Access = public)
       myStruct = struct()
    
  
    
    end
 % Create ListBox
            app.ListBox = uilistbox(app.AgeTab);
            app.ListBox.Items = {'18-28', '29-39', '40-50', '51-61', '62-72', '73-83'};
            app.ListBox.ValueChangedFcn = createCallbackFcn(app, @ListBoxValueChanged, true);
            app.ListBox.FontName = 'Arial Black';
            app.ListBox.FontSize = 24;
            app.ListBox.FontColor = [0.3922 0.8314 0.0745];
            app.ListBox.BackgroundColor = [0.502 0.502 0.502];
            app.ListBox.Position = [40 350 795 169];
            app.ListBox.Value = '18-28';
            % Create GenderTab
            app.GenderTab = uitab(app.TabGroup);
            app.GenderTab.Title = 'Gender';
            app.GenderTab.BackgroundColor = [0.502 0.502 0.502];

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Answer 1

Voss 2022-11-22

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The code above creates and initializes a couple of components (a uilistbox and a uitab). Those components are stored in the app object, and anything you need to know about those components, you can get at any time.

For instance, the expression

app.ListBox.Value

returns the Value of app.ListBox at the time the command is run.

Generally, there is no need to create a separate data structure mirroring the state of a GUI; you can simply get the state of the GUI at any time.

What are you trying to accomplish by making a separate struct that mirrors the GUI state (if that is in fact the intention)?

(Having said that, assuming you have a good reason to do this, you can keep your struct up to date by updating it in the callbacks of your components.)

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Voss 2022-11-22

编辑：Voss 2022-11-22

(Replying also to this comment.)

If I understand correctly, there is no need to store a data structure which needs to be updated whenever the user makes a selection in the GUI. What you can do instead is to save the GUI state (or the relevant properties from the GUI) one time when the program is closed. To do that, define a CloseRequestFcn, which will grab the things you need (e.g., app.ListBox.Value, app.ListBox_3.Value, etc.) and save them to a mat file (or other type of file). Then you have the selections made by that user and you can use that mat file in your post-analysis.

If each user might run the program multiple times, you can check if your mat file already exists before saving, and if so give it a different name, or better: name the file with a time-stamp so you know when the data was collected, or better yet: use a time-stamp and a user ID. (Or simply append the selections made in each new run to the existing mat file.)

Would that be sufficient for your purpose? Or do you also need to be able to initialize the GUI into a particular state, which may vary?

Voss 2022-11-23

编辑：Voss 2022-11-23

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OK, in that case, you can create one mat file each time a user is done with the app. You can generate the mat file name based on the current time, since you know that you'll never get the same name twice (unless this is running on more than one machine and two users might finish at the same time, in which case you'd need some other identifier in the file name as well, such as a machine ID).

Maybe something like this:

function EXITButtonPushed(app, event)
    file_name = sprintf('%s.mat',datetime(now(),'ConvertFrom','datenum','Format','yyyy_MM_dd_HH_mm_ss_SSS'));
    selections = { ... % TBD: include all settings you want to save here
        app.ListBox.Value ...
        app.ListBox_3.Value ...
        app.ListBox_4.Value ...
        };
    save(file_name,'selections');
    app.delete % deletes the app
end

I recommend NOT using that function as the uifigure's CloseRequestFcn but only as the EXITButton callback, because the user could close the app before finishing and presumably you don't want to save the settings in that case - you only want to save complete datasets. In fact, it might be a good idea to prevent the user from closing the app (other than with the EXIT button), by setting the CloseRequestFcn to some function that does nothing, e.g.:

% Close request function: UIFigure
function do_nothing(~,~)
% do nothing. don't close the app. do nothing.
end

Nwasinachi 2022-11-29

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@Voss Why do you think it is saying the wordarray is undefined?

%attempt for text area Question 1
           Correct=0;
           Incorrect=0;
                       
firstopt = 'The boy went to school'; % will change text and number of the
Secoption = 'The man went to church';
thoption = 'The girl is going there';
wordarray = {firstopt Secoption thoption};
app.TextArea7_2.Value = wordarray{randi(numel(wordarray))}; %% randomization works. 

function ListBox2ValueChanged(app, event)
            value = app.ListBox2.Value;
            if strcmp(app.ListBox2.Value,'YES')||strcmp(app.ListBox2.Value,'NO');
                set(app.NEXTButton_7,'Enable','on');
            end
% This is giving me an error saying wordarray is an undefined variable, but
% i have clearly defined it in the code above.
            if app.TextArea7_2.Value==wordarray{1} && app.ListBox2.Value =='YES';
                Correct = Correct+1;% a loop where if this option is displayed and YES is selected from list box then the response is correct
            else Incorrect = Incorrect+1;
           end 

Voss 2022-11-29

在 MATLAB Online 中打开

Each function has its own workspace, so ListBox2ValueChanged doesn't know about wordarray because wordarray is defined inside another function.

In an app, you can make a variable an app property and define it in the startup function so that it can be seen by all functions in the app. You can do that for wordarray by including this in your startup function:

firstopt = 'The boy went to school'; % will change text and number of the
Secoption = 'The man went to church';
thoption = 'The girl is going there';
app.wordarray = {firstopt Secoption thoption};

and refer to app.wordarray instead of wordarray everywhere.

Nwasinachi 2022-11-29

编辑：Nwasinachi 2022-11-29

在 MATLAB Online 中打开

@Voss i set wordarray as a variable in the property

  properties (Access = public)
        wordarray % Description
        end
     

Changed it to app.wordarray everywhere that i need it.

         %attempt for text area Question 1
           Correct=0;
           Incorrect=0;               
firstopt = 'The boy went to school'; % will change text and number of the
Secoption = 'The man went to church';
thoption = 'The girl is going there';
app.wordarray = {firstopt Secoption thoption};
app.TextArea7_2.Value = app.wordarray{randi(numel(app.wordarray))}; %% randomization works. 

But this line is still giving me an error. i have used app.wordarray{firstopt} which it stated that it wasnt a defined variable. Do i need to add that variable into the properties as well?

 if app.TextArea7_2.Value==app.wordarray{1} && app.ListBox2.Value =='YES';
                Correct = Correct+1;% a loop where if this option is displayed and YES is selected from list box then the response is correct
            else Incorrect = Incorrect+1;
           end  
        

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