Matlab Gui plot doesn't animate using drawnow.

I am new in GUI. I have a GUI with a single axes that loads a .mat file. from The .mat file, I convert a 18000*132 matrix called "MelisaW". Then I tried to plot few of the sequences of rows of that matrix with scatter3. The code is as below:

    function open_OpeningFcn(hObject, eventdata, handles, varargin)
 % This function has no output args, see OutputFcn.
 % hObject    handle to figure
 % eventdata  reserved - to be defined in a future version of MATLAB
 % handles    structure with handles and user data (see GUIDATA)
 % varargin   command line arguments to open (see VARARGIN)
 % Choose default command line output for open
   handles.output = hObject;
   load('PMelisa01.mat', 'PMelisaD20180404Walkingnone01');
   MelisaW = cell2mat(PMelisaD20180404Walkingnone01):
   ax1 = handles.axes1;
   for i=1:200
    PMelisaD20180404Head_x= MelisaW(i,4)/100;
    PMelisaD20180404Head_y= MelisaW(i,5)/100;
    PMelisaD20180404Head_z= MelisaW(i,6)/100;
    %2....
    scatter3(ax1,PMelisaD20180404Head_x,PMelisaD20180404Head_y,PMelisaD20180404Head_z,'filled')
    %2 scatter3(..)...
    drawnow 
     end
 % Update handles structure
  guidata(hObject, handles);
  function varargout = open_OutputFcn(hObject, eventdata, handles) 
% varargout  cell array for returning output args (see VARARGOUT);
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% Get default command line output from handles structure
 varargout{1} = handles.output;

I Used the "drawnow" command to animate the scatter plots but instead of plotting for 200 times it only shows 200th plot. I have used the same code as normal .m file and it animated. It is not working only on GUI. Any help to solve the problem is highly appreciated.

Answer 1

[Walter Roberson]

You do not appear to have a "hold on", and you are scatter3() only a single point at a time. MATLAB is going to create the one point, yes, but it is going to automatically create xlim and ylim according to the data, and would mostly end up centering the point on the display. The result would be a point staying mostly in the same screen location while the axes changes to reflect the position.

If you had a hold on in effect, then it would be adding to the displayed points instead.

You should also be considering switching to animatedline for this purpose instead of doing a scatter3() each time.