MATLAB: Does EXIST work in GUIDE (GUI)

existfiggui

Hello, I have a little problem with EXIST function. I'm having a button with some calculations in code but later in code there is modification button(that asignin to workspace some other values). I've tride simple IF function (if exist modified value in workspace then do something else). But It does not work

if exist('N1pg','var')==0 
....
else 
...
end
if(get(handles.radiobutton10,'Value'))== (get(handles.radiobutton10,'Max'))
N1pg=str2num(get(handles.edit86,'String'));
assignin('base','N1pg',N1pg);

Thank you for solution\fix.

Best Answer

EXIST checks the existence in the workspace of the current function. ASSIGNIN('base', ...) assigns the variable in the base workspace. Therefore EXIST cannot see the variable.

Creating variables in another workspace is a frequent source of problems. It is more stable to create the variables locally in the GUI (see GUIDATA, UserData, ApplicationData) and use a dedicated function to export them on demand only.

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You can send commands to base workspace using the evalin() function as you mentioned. For example you can say:

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and to clear a variable myvarinbase say

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Note that

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will remove variables var1 var2 from the current workspace, not necessarily base workspace, if it is called from inside a function like a GUI.

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Nik - you could put this code in either the _CreateFcn for the uitable, or the _OpeningFcn of your GUI. If the former, then the code would be something like

 function uitable1_CreateFcn(hObject, eventdata, handles)
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The above code would be near-identical for the _OpeningFcn - all you would have to do is replace hObject with handles.uitable1.

Note how the above code checks to see if the variable exists before trying to access it using evalin.

In the above example, Table was created in the workspace as

 Table = randi(255,12,4);

Best Answer

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