Using the Save command to save a logical mask

I am attempting to use the Matlab save command to save a logical mask as a .mat file. The difficulty arises when I attempt to specify a path to save the file in. I need to be able to save the mask in a specific folder. I have tried multiple incarnations of this code:

handles = guidata(hObject);

Folder = uigetdir('C:\Users\c13459232\Documents\MATLAB\Completed code thus far\Mask');
filename = 'Mask_01.mat';
%handles.mask = mask;
save([Folder filename '.mat'], 'handles.mask');

guidata(hObject, handles);

handles.mask is the logical mask itself, created in another callback. I attempted to use the command form of save, I also tried simply saving handles.mask without any folder specified. The main error that occurs is Argument must contain a string but Matlab also does not recognize the mask with the error Undefined function or variable 'mask' also occurring. Is there something glaring I am doing wrong here?

[Stephen23]

"Is there something glaring I am doing wrong here?"

You are using code taken from answers that you have been given by the volunteers who help you, yet you are not willing to make the small gesture of thanks of accepting those answers. You have many perfectly good answers that have not been accepted:

https://www.mathworks.com/matlabcentral/profile/authors/9670029-aaron-smith

https://www.mathworks.com/matlabcentral/answers/351413-saving-a-logical-mask

[Stephen23]

save([Folder filename '.mat'], 'handles.mask')

When you read the save documentation, it describes the second input as "variables — Names of variables to save". Is handles.mask a variable? No, it is a field within a structure. You need to pass save the name of a variable, just like the function documentation states.

[Aaron Smith]

I assigned handles.mask the name mask. The handles structure simply allows me to share files between callbacks so to my understanding, this new value mask should be the logical mask from the previous callback which is stored in the handles.mask field. I understand what you mean now, that the logical mask itself isn't a variable because it is a matrix with a large number of values so the apostrophes are not necessary, but how does this change the syntax of the save command? By making mask = handles.mask, why is mask not simply the mask that i created handles.mask to share in the previous callback?

Folder = uigetdir('C:\Users\c13459232\Documents\MATLAB\Completed code thus far\Mask');
filename = 'Mask_01.mat';
mask = handles.mask;
save(fullfile(Folder, filename), mask);

This returns the error: Argument must contain a string. I replaced filename with the actual 'mask_01.mat', this returned the same error. I am trying to save a logical matrix as a .mat file, disregarding the folder for a moment, should this not simply be a case of save( 'name_of_created_file.mat', 'name_of_mask')?

[Adam]

save(fullfile(Folder, filename), 'mask');

The variable still has to be passed in by name. This catches me out a few times as it is unintuitive, but it is the way it is.

[Aaron Smith]

I tried it with the apostrophes and without. It doesn't work either way

[Aaron Smith]

I tried it again, and now I think it is working. Thanks

[José-Luis]

Emphasizing what Stephen said, please accept the answer that best solves your problem.

[Stephen23]

" By making mask = handles.mask, why is mask not simply the mask that i created handles.mask to share in the previous callback?"

It is.

" I understand what you mean now, that the logical mask itself isn't a variable because it is a matrix with a large number of values so the apostrophes are not necessary"

Not at all. The fact you have a matrix of values is irrelevant. What is relevant is that handles.mask is, in itself, not a variable. A variable has a name and that name can be found in some workspace. Can you see handles.mask in the workspace? No, you cannot. You can see handles in the workspace though. This means that handles is a variable. And, as the save documentation clearly states, save requires the name of a variable in the workspace. Not the name of a field of structure, not the title of a figure, not your aunts name, or anything else. Just the name of a variable. Knowing what a variable is is a very basic MATLAB concept, covered in the introductory tutorials:

https://www.mathworks.com/help/matlab/getting-started-with-matlab.html

Who mentioned anything about "the apostrophes are not necessary" ? I certainly didn't write that, and I cannot see that written in the answer below.

PS: "please accept the answer that best solves your problem." and also for many of your previous questions. Most volunteers do not like the feeling of being treated as a disposable service.

Answer 1

[José-Luis]

 data = handles.mask;
 save('someFile.mat','data');