MATLAB: Save a structure that is within a structure

MATLABsavestructure within structure

I am trying to save a structure called UserData that is in the handles structure – used in my GUI.

So far I can only save it if I create a copy outside of the handles structure.

UserData = handles.UserData
save(FullPath,UserData)

Is there a way to do it with simply the save function? Something like this:

save(FullPath, handles.'Car')

If there is I have not found the correct syntax to do so.

Best Answer

You can save a structure from within a structure only in the very limited case that the parent structure is a scalar structure array and that all fields within the parent structure are to individually become variables in the mat file. The handles structure is a scalar structure so it meets the first requirement but it is quite unlikely that you want to save all parts of it to become individual variables.

It is likely that you will need to save the content of the substructure to a variable and then save the variable.

Car = handles.Car;
save(FullPath, 'Car')

The one exception I mentioned would look like

save(FullPath, '-struct', 'handles')

Related Solutions

MATLAB: Save data from MatLab GUI to struct .mat file

You should always load to a struct. That makes it clear where variables come from. Then it is also easier to extend the struct instead of creating a new struct every time like you're doing.

% --- Executes on button press in saveBeats.
function saveBeats_Callback(hObject, eventdata, handles)
% hObject    handle to saveBeats (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
if exist('beatData.mat','file')
    S=load('beatData.mat');beatData=S.beatData;
else
    beatData = struct('filename',{},'numberOfBeats',{});   %creation of simple struct with two fields: 'filename' and 'numberOfBeats')
end
currentFileName = getappdata(0,'currFile');            %gets the name of current audiosample
currentBeats = get(handles.numBeats,'Value');          %gets the number of beats written in the edit box
currentIndex = get(handles.listbox1,'Value');          %gets the index of the current audiosample from a listbox
beatData(currentIndex).filename = currentFileName;     %saves the name of the audiofile to 'filename'-field in the struct beatData at index
beatData(currentIndex).numberOfBeats = currentBeats;   %saves the number of beats 
save('beatData.mat', 'beatData');        %save the struct as a .mat file

MATLAB: Structures

You could have the following structure:

s.myfield = 10;
s.another = 20;
s.hello   = 30;

Now suppose you have a list with the fieldnames which also happens to be the function to retrieve them from a structure:

fnames = {'myfield','another','hello'};

(Note that I didn't call the list with the name of the function)

Now you can manipulate the structure using dynamic fieldname indexing:

for n = 1:numel(fnames)
    tmp = s.(fnames{n});
    % do stuff with tmp or directly with s.(fnames{n}) 
end

This is a complete reference to manipulate structures: structures

Best Answer

Related Solutions

MATLAB: Save data from MatLab GUI to struct .mat file

MATLAB: Structures

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