MATLAB: Axes error in GUI

matlab gui

I am trying to move through a series of images in a GUI but receive the following error when pressing the 'next block' button following the load button. The 'next block' button should display on the two axes on the screen the next 2 figures
{Error: Struct contents reference from a non-struct array object.
Error in Block_Sort>next_block_Callback (line 93) a1 = axes(handles.axes1);
Error in gui_mainfcn (line 95) feval(varargin{:});
Error in Block_Sort (line 42) gui_mainfcn(gui_State, varargin{:});
Error in matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)Block_Sort('next_block_Callback',hObject,eventdata,guidata(hObject)) 93 a1 = axes(handles.axes1);
} function next_block_Callback(hObject, eventdata, handles)
% hObject handle to next_block (see GCBO)
% eventdata reserved – to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
images = guidata(hObject);
a1 = axes(handles.axes1);
a2 = axes(handles.axes2);
for i = 1:length(images)
I = images{i+1};
J = images{i+2};
imshow(a1,I);
imshow(a2,J);
end
function load_Callback(hObject, eventdata, handles)
% hObject handle to load (see GCBO)
% eventdata reserved – to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
addpath(pwd)
animal = evalin('base','animal');
foldname = ['Selected-Figures-' animal '*'];
filename = dir(foldname);
dinfo = dir(filename.name);
addpath(filename.name);
names_cell = {dinfo.name};
names_cell = names_cell(3:end);
images = cell(1,length(names_cell));
for i = 1:length(names_cell)
    curr_file_name = names_cell{i};
    curr_im = imread(curr_file_name);
    images{i} = curr_im;
end
guidata(hObject,images);
I = imread(names_cell{1});
I = imresize(I,2);
J = imread(names_cell{2});
J = imresize(J,2);
axes(handles.axes1);
imshow(I);
axes(handles.axes2);
imshow(J);

Best Answer

Geoff's answer will probably resolve your initial error, but you'll probably run into issues at the same place. Note that Axes cannot return an output if used like a1 = axes(handles.axes1).
EXAMPLE:
   handles.axes1 = axes; %Creates a new axes
   a1 = axes(handles.axes1); %ERROR: Too many output arguments
If you want to draw an image in a particular axes, use the 'Parent' option like this:
imshow(I, 'parent', handles.axes1)
That way, you don't have to track which axes is the first axes, etc. Another way is to directly set the imshow's CData property.
Ix = imshow([], 'parent', handles.axes1); %initialize the imshow handle somewhere
Ix.CData = rand(100);   %change the image shown by the imshow area
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