sad grad student can't handle GUIs - please help

Hi, all. I have no experience building GUIs in MATLAB so sorry if this is a naive question. I am trying to use a toolbox called DETECT which uses autoregressive model for feature extraction with EEG data. I have attached the PDF labeled "DETECT" which describes the toolbox in depth. And here is a link to the article: https://pubmed.ncbi.nlm.nih.gov /23638169/

The last update of this toolbox was in 2013, according to Github. I am running into trouble with the function getLabels, which calls eegplot2, a modified version of the function eegplot from EEGLAB. From input 2D array of size (channels, frames), getLabels should return a GUI with scrolling visualization of the EEG signal and color-coded tabs for each feature category the user defines to use for model building. However, when I run getLabels, no GUI appears, and instead, I get the following error:

Error using matlab.graphics.Graphics/set

The name 'Units' is not an accessible property for an instance of class 'matlab.graphics.GraphicsPlaceholder'.

Error in eegplot2 (line 631)

set(u,'Units','Normalized')

What does this error mean and how do I fix it? Here is that section of code:

 
  % %%%%%%%%%%%%%%%%%%%%%%%%%
  % Set up uicontrols
  % %%%%%%%%%%%%%%%%%%%%%%%%%

% positions of buttons
  posbut(1,:) = [ 0.0464    0.0254    0.0385    0.0339 ]; % <<
  posbut(2,:) = [ 0.0924    0.0254    0.0288    0.0339 ]; % <
  posbut(3,:) = [ 0.1924    0.0254    0.0299    0.0339 ]; % >
  posbut(4,:) = [ 0.2297    0.0254    0.0385    0.0339 ]; % >>
  posbut(5,:) = [ 0.1287    0.0203    0.0561    0.0390 ]; % Eposition
  posbut(6,:) = [ 0.4744    0.0236    0.0582    0.0390 ]; % Espacing
  posbut(7,:) = [ 0.2762    0.01    0.0582    0.0390 ]; % elec
  posbut(8,:) = [ 0.3256    0.01    0.0707    0.0390 ]; % g.time
  posbut(9,:) = [ 0.4006    0.01    0.0582    0.0390 ]; % value
  posbut(14,:) = [ 0.2762    0.05    0.0582    0.0390 ]; % elec tag
  posbut(15,:) = [ 0.3256    0.05    0.0707    0.0390 ]; % g.time tag
  posbut(16,:) = [ 0.4006    0.05    0.0582    0.0390 ]; % value tag
  posbut(10,:) = [ 0.5437    0.0458    0.0275    0.0270 ]; % +
  posbut(11,:) = [ 0.5437    0.0134    0.0275    0.0270 ]; % -
%   posbut(12,:) = [ 0.6    0.02    0.14    0.05 ]; % cancel
%   posbut(13,:) = [-0.15   0.02    0.07    0.05 ]; % cancel
  posbut(12,:) = [ 0.6    0.02    0.14    0.05 ]; % cancel
  posbut(13,:) = [ 0.6    0.02    0.14    0.05  ]; % cancel
  posbut(17,:) = [-0.06    0.02    0.09    0.05 ]; % events types
  posbut(20,:) = [-0.17   0.15     0.015    0.8 ]; % slider
  posbut(:,1) = posbut(:,1)+0.2;

% Five move buttons: << < text > >> 

  u(1) = uicontrol('Parent',figh, ...
	'Units', 'normalized', ...
	'Position', posbut(1,:), ...
	'Tag','Pushbutton1',...
	'string','<<',...
	'Callback','eegplot2(''drawp'',[],[],1)');
  u(2) = uicontrol('Parent',figh, ...
	'Units', 'normalized', ...
	'Position', posbut(2,:), ...
	'Tag','Pushbutton2',...
	'string','<',...
	'Callback','eegplot2(''drawp'',[],[],2)');
  u(5) = uicontrol('Parent',figh, ...
	'Units', 'normalized', ...
	'BackgroundColor',[1 1 1], ...
	'Position', posbut(5,:), ...
	'Style','edit', ...
	'Tag','EPosition',...
	'string', fastif(g.trialstag(1) == -1, '0', '1'),...
	'Callback', 'eegplot2(''drawp'',[],[],0);' );
  u(3) = uicontrol('Parent',figh, ...
	'Units', 'normalized', ...
	'Position',posbut(3,:), ...
	'Tag','Pushbutton3',...
	'string','>',...
	'Callback','eegplot2(''drawp'',[],[],3)');
  u(4) = uicontrol('Parent',figh, ...
	'Units', 'normalized', ...
	'Position',posbut(4,:), ...
	'Tag','Pushbutton4',...
	'string','>>',...
	'Callback','eegplot2(''drawp'',[],[],4)');

% Text edit fields: ESpacing

  u(6) = uicontrol('Parent',figh, ...
	'Units', 'normalized', ...
	'BackgroundColor',[1 1 1], ...
	'Position', posbut(6,:), ...
	'Style','edit', ...
	'Tag','ESpacing',...
	'string',num2str(g.spacing),...
	'Callback', 'eegplot2(''draws'',[],[],0);' );

% Slider for vertical motion
  u(20) = uicontrol('Parent',figh, ...
	'Units', 'normalized', ...
	'Position', posbut(20,:), ...
   'Style','slider', ...
   'visible', 'off', ...
   'sliderstep', [0.9 1], ...
   'Tag','eegslider', ...
   'callback', [ 'tmpg = get(gcbf, ''userdata'');' ... 
   				'tmpg.elecoffset = get(gcbo, ''value'')*(tmpg.chans-tmpg.dispchans);' ...
               'set(gcbf, ''userdata'', tmpg);' ...
               'eegplot2(''drawp'',[], [], 0);' ...
               'clear tmpg;' ], ...
   'value', 0);

% Channels, position, value and tag

  u(9) = uicontrol('Parent',figh, ...
	'Units', 'normalized', ...
	'BackgroundColor',DEFAULT_FIG_COLOR, ...
	'Position', posbut(7,:), ...
	'Style','text', ...
	'Tag','Eelec',...c
	'string',' ');
  u(10) = uicontrol('Parent',figh, ...
	'Units', 'normalized', ...
	'BackgroundColor',DEFAULT_FIG_COLOR, ...
	'Position', posbut(8,:), ...
	'Style','text', ...
	'Tag','Etime',...
	'string','0.00');
  u(11) = uicontrol('Parent',figh, ...
	'Units', 'normalized', ...
	'BackgroundColor',DEFAULT_FIG_COLOR, ...
	'Position',posbut(9,:), ...
	'Style','text', ...
	'Tag','Evalue',...
	'string','0.00');

  u(14)= uicontrol('Parent',figh, ...
	'Units', 'normalized', ...
	'BackgroundColor',DEFAULT_FIG_COLOR, ...
	'Position', posbut(14,:), ...
	'Style','text', ...
	'Tag','Eelecname',...
	'string','Chan.');
  u(15) = uicontrol('Parent',figh, ...
	'Units', 'normalized', ...
	'BackgroundColor',DEFAULT_FIG_COLOR, ...
	'Position', posbut(15,:), ...
	'Style','text', ...
	'Tag','Etimename',...
	'string','Time');
  u(16) = uicontrol('Parent',figh, ...
	'Units', 'normalized', ...
	'BackgroundColor',DEFAULT_FIG_COLOR, ...
	'Position',posbut(16,:), ...
	'Style','text', ...
	'Tag','Evaluename',...
	'string','Value');

% ESpacing buttons: + -
  u(7) = uicontrol('Parent',figh, ...
	'Units', 'normalized', ...
	'Position',posbut(10,:), ...
	'Tag','Pushbutton5',...
	'string','+',...
	'FontSize',8,...
	'Callback','eegplot2(''draws'',[],[],1)');
  u(8) = uicontrol('Parent',figh, ...
	'Units', 'normalized', ...
	'Position',posbut(11,:), ...
	'Tag','Pushbutton6',...
	'string','-',...
	'FontSize',8,...
	'Callback','eegplot2(''draws'',[],[],2)');

  %if isempty(g.command) %tmpcom = 'fprintf(''Rejections saved in variable TMPREJ\n'');';   
  %else 
  tmpcom = g.command;
  %end;
  acceptcommand = [ 'g = get(gcbf, ''userdata'');' ... 
				    'TMPREJ = g.winrej;' ...
                    'if g.children, delete(g.children); end;' ...
                    'delete(gcbf);' ...
		  				  tmpcom ...
                    '; clear g;']; % quitting expression
                
                
    u(13) = uicontrol('Parent',figh, ...
        'Units', 'normalized', ...
        'Position',posbut(13,:), ...
        'string',fastif(isempty(g.command),'CLOSE', 'CONTINUE'), 'callback', ...
        [	'g = get(gcbf, ''userdata'');' ...
        'if g.children, delete(g.children); end;' ...
        'close(gcbf);' ...
        'clear TMPREJ g;'] );
        
  if ~isempty(g.command)
	  u(12) = uicontrol('Parent',figh, ...
						'Units', 'normalized', ...
						'Position',posbut(12,:), ...
						'Tag','Accept',...
						'string',g.butlabel, 'callback', acceptcommand);
  end;


  if ~isempty(g.events)
      u(17) = uicontrol('Parent',figh, ...
                        'Units', 'normalized', ...
                        'Position',posbut(17,:), ...
                        'string', 'Event types', 'callback', 'eegplot2(''drawlegend'', [],[],gcbf)');
  end;

  set(u,'Units','Normalized')

Answer 1

[Walter Roberson]

u(12) and u(17) are only created conditionally . If either of them is not set, then at least one element of u would not be a valid graphics object, and would instead have been filled in with a matlab.graphics.GraphicsPlaceholder object. Such objects mean "this is the right data type to be a graphics object of some kind, but no graphics was assigned to it"

You have two ways to proceed:

1. You could create u(12) and u(17) unconditionally, but use conditions to determine whether you make them visible; OR
2. set( u(ishghandle(u)), 'Units', 'Normalized' )

[Allison Moore]

Thank you so much! Your explanation of the error message was really helpful. It works now!