How to I cumulatively add data to a matrix in a GUI using a push button?

I want to create a GUI with 2 edit boxes and one button. When I type numbers into the edit boxes (e.g. 1 and 2), and then click the button, I want the code to append these to numbers to a matrix N so that it becomes N = [1 2]. When I type new numbers (e.g. 3 7) and press the button, N should become N = [1 2; 3 7]. How do I do this appending process and how can I save this matrix to be used for other functions in the GUI?

Cheers!

Answer 1

[KL]

A = []; %initialize

then something like the following for your pushbutton callback

function pushbutton_callback(src,event)
      s1 = get( handles.edit1, 'String');
      s2 = get( handles.edit2, 'String');
      n1 = str2double(s1);
      n2 = str2double(s2);
      A = [A; n1, n2];
end

also make sure that you throw a message if they enter anything other than numbers.

[Pedro Damas]

Ahhh so smart! Thank youuu that's perfect! My only question is about the code

A = []; %initialize

Does this go under the opening function?

[Adam]

You would need to attach it to handles, otherwise it will not be available in the callback.

handles.A = [];

in the OpeningFcn if you are using GUIDE and then access it in the callback similarly. You also need to call the guidata function. A GUIDE callback would generally look more like

function pushbutton_callback( hObject, eventdata, handles )

so:

handles.A = [handles.A; n1, n2];
guidata( hObject, handles )

should work.

If you are not using GUIDE there are other approaches.

[Pedro Damas]

Thank you so much!

[Pedro Damas]

Why doesn't A save the previous values? Right now, all it does it saving the current values and the previous ones just vanish.. Help?

[KL]

Probaby you need to write A = []; only in the beginning/initialization script ( just once ), not inside your callback.

[Adam]

I edited my comment a little after you first replied to it, which may help.

[Pedro Damas]

I'm not entirely sure if that would work, but something that did was writing

guidata(hObject,Handles)

at the end of the pushbutton function!

I don't know why it works, so if you know please explain :p But I'm glad it works now! Thanks for the help!

[KL]

Thanks Adam.

[Adam]

handles is just a structure, it gets passed into your callback from GUIDE, but what you have is a local copy. If you make changes to it they get lost when the function goes out of scope, like any other local variable.

guidata( hObject, handles )

embeds your updated handles back into the GUI so that next time a callback is triggered it will provide the updated handles.

[Pedro Damas]

Ah that makes sense! Thank you both Adam and KL!