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How to use guidata to save data in external MATLAB function?

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Hi all,
I'm writing a GUI that uses external function m files. I call handles into the function to use values in a for loop. I eventually want to overwrite handles with the new value found from the for loop.
handles.struct.variable = 0; % initialized in GUI main code
for x = 1:100
variable = handles.struct.variable(x)
variable = some equation/code;
handles.struct.variable(x) = variable
guidata(hObject, handles) %<--------- this is my issue
I pre-allocated the structure I'm using, but when I try to save the data using 'guidata(hObject, handles) I get an error:
"Undefined function or variable 'hObject'."
Does anyone know a way to save the data to handles in a function file written outside of the GUI?

Accepted Answer

Walter Roberson
Walter Roberson on 1 Aug 2017
To use guidata to update the master copy of the handles, you need to know at least one graphics object that is part of the figure that has the guidata attached to it. It can be anything inside the figure -- a uicontrol, an axes, a line, a context menu, anything. Perhaps you have an appropriate object inside the handles structure already.
If not, then you can use findobj(), provided you know something unique about some object that is inside the figure. You can findobj() to locate all figures, but if you don't know something about the one acting as your GUI then you might accidentally end up with multiple figures and pick the wrong one.
rbme17 on 2 Aug 2017
Edited: rbme17 on 2 Aug 2017
Whoops! Seems to work fine now, thanks Walter!

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