How to clear GUI variables?

Question

Kev 2013-12-17

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https://ww2.mathworks.cn/matlabcentral/answers/110044-how-to-clear-gui-variables

编辑： Kev 2013-12-18

Hi,

I'm trying to clear GUI variables. From what I understand, each callback function has its own workspace and separate global workspace. I'd like to clear a specific callback variables with a push button. (Callback function is blockremover_callback, I'd like to reset with a push button).

Thanks!

function clearscreen_Callback(hObject, eventdata, handles)
global xy h binary 
%evalin('base','clear h')
clear blockremover_callback 
xy = []; 
h = []; 
binary = []; 
%evalin('base','clear all');
cla;

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Answer 1

Image Analyst 2013-12-18

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在 MATLAB Online 中打开

You can clear global variables with clear global.

clear global xy;
clear global h;
clear global binary;

After you clear them, if you need them you need to declare them again:

global xy;
global h;
global binary;

There is no need to clear local variables as they vanish once the function exits.

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Kev 2013-12-18

编辑：Walter Roberson 2013-12-18

在 MATLAB Online 中打开

I'm still getting the error after clearing those three variables. My objective is to to allow user to use the tool without closing and reopening for collecting data from several images.

Steps are as follows:

Load image
calibrate it once from the scale
remove messy regions from the image
follow the rest (procedure to get diameters).

After above steps done, user can click a push button to reset all the variables so we don't get mixed data (and to minimize run time errors also). After that, user can load another file, but when we try to use that impoly enclosed region removal function, it is giving error. I initially thought it would have been due to not clearing the variables for second run.

Error using imroi/parseInputsForCreateMask (line 83)
Ambiguous syntax. Associated axes contains more than one image. Specify image handle as input argument
to resolve ambiguity. Type "help imroi/createMask" for more information.
Error in imroi/createMask (line 245)
            [obj,h_im] = parseInputsForCreateMask(varargin{:});
Error in FibGUI>blockremover_Callback (line 123)
    binary = h2.createMask();
Error in gui_mainfcn (line 96)
        feval(varargin{:});
Error in FibGUI (line 42)
    gui_mainfcn(gui_State, varargin{:});
Error in @(hObject,eventdata)FibGUI('blockremover_Callback',hObject,eventdata,guidata(hObject))
Error while evaluating uicontrol Callback

------------------------------------------------------------------------------

Code involving this two functions: 
function blockremover_Callback(hObject, eventdata, handles)
% hObject    handle to blockremover (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
global read_image burnedImage xy binary h2 
colour_to_gray = rgb2gray(read_image);
filtered_image = medfilt2(colour_to_gray); 
axes(handles.axes10) 
imshow(filtered_image);
burnedImage = filtered_image; 
while true
    % some code to do masking
    h2 = impoly(); 
      binary = h2.createMask();
      xy = h2.getPosition;
      burnedImage(binary) = 255;
      axes(handles.axes10) 
      imshow(burnedImage)
      % Ask if user wants to do another one.
      promptMessage = sprintf('Do you want to Continue masking,\or Cancel to abort processing?');
      titleBarCaption = 'Continue?';
      button = questdlg(promptMessage, titleBarCaption, 'Continue', 'Cancel', 'Continue');
      if strcmpi(button, 'Cancel')
    break;
      end
  end
function binarize_Callback(hObject, eventdata, handles)
% hObject    handle to binarize (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
%Global variables used from other functions or declared as global to be 
%used in other functions 
global binary read_image ratio_value burnedImage
%colour_to_gray filtered_image
set(handles.edit13, 'String' , ratio_value); 
%%%WANT impoly region removal optional.  
if (burnedImage ==0)
      rgb = read_image; 
      gray = rgb2gray(rgb); 
      filtered_gray = medfilt2(gray); 
      level = graythresh(filtered_gray);
      binary = im2bw(filtered_gray, level);
      axes(handles.axes10);
      imshow(binary);
else 
     gray2bin = burnedImage;
     level = graythresh(gray2bin);
     binary = im2bw(gray2bin, level);
     axes(handles.axes10);
     imshow(binary);
end

Image Analyst 2013-12-18

Like I said in your other question, if it thinks there is more than one image in an axes, then call cla('reset') before calling imshow() so that the axes is emptied before loading an image into it.

Kev 2013-12-18

编辑：Kev 2013-12-18

Perfect! Wish thre were emoticons on this forum. :) The problem was with resetting axis. I thought it was something else. I applied cla command in the block. I didn't know there were separate cla('reset') function also. Anyways, Thanks very much!!!

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Answer 2

Walter Roberson 2013-12-17

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https://ww2.mathworks.cn/matlabcentral/answers/110044-how-to-clear-gui-variables#answer_118674

No, there is only one global workspace.

Each function may have its own persistent variables. Those variables may be cleared by using "clear" together with the function name.

http://matlab.wikia.com/wiki/FAQ#How_can_I_share_data_between_callback_functions_in_my_GUI.3F

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Kev 2013-12-18

编辑：Kev 2013-12-18

Thanks for providing link. That wiki is informative. Bookmarked! :)

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