How to store data without deleting previous one

Hello,

I'm writing a program using App Designer that allows you to select a ROI using drawfreehand in a picture, then switch to the next picture using a "NEXT" button and draw over it again. For the drawfreehand function I have another button named ('DRAW').

I need to store the binary masks of the selected ROIs so I can use them later, but when I try to do it the program only saves the one from the last picture and deteles the previous ones.

How can I solve this?

Here is my code:

function NEXT(app, event)
%this function works fine to switch to the next image         
k=length(app.complete); 

if app.num<k 
app.num=app.num + 1;
end

ISig = dicomread(app.complete{app.num}); 
imshow(ISig,[],'Parent',app.UIAxes);



function DRAW(app, event) 
           
contE(app.num)=drawfreehand(app.UIAxes,'color','white');
mask{app.num}=createMask(contE(app.num));
            
save mask.mat mask


% app.num is a property that indicates de index of the image displayed and
% k represents the number of images loaded

[Jan]

You are updating "mask", but save "maskE". Is this a typo in the forum only or in your code?

[María Pérez Fernández]

You're right, thank you. It was a typo in the forum only, I have already corrected it.

[Jan]

mask{app.num} = createMask(contE(app.num));
save mask.mat mask

This appends a new cell element to mask and stored the complete arrays. This should work and loading mask.mat should contain all stored masks.

So maybe you are not using the current mask.mat file? You did not provide an output folder in the save command. Safer:

save(fullfile(yourOutputfolder, 'mask.mat'), 'mask');

Of course, now you have to define yourOutputfolder accordingly.

[María Pérez Fernández]

Hello,

I have done this but when I load mask.mat it only contains the last mask created, and all the other entrys are zero.

Thank you very much

Answer 1

[Voss]

mask is a variable that only exists in the workspace of the DRAW function. In other words, each time DRAW is executed, a new mask variable is created and saved to the mat file.

To save the values of mask from multiple executions of DRAW, you can make mask an app property.

[María Pérez Fernández]

Thank you very much, It works now!

[Voss]

You're welcome!