Is there a way to control two subplots with one slider?

Can anyone demonstrate a way to update both subplots with one uicontrol slider?

In my case I have two matlab arrays with size (1024,128,20). I want to imshow 2d images of size 1024 x 128 for each of the third dimension using a slider and only one slider updating both subplots.

Thanks in advance

[Geoff Hayes]

@Derrell Dsouza - did you create your GUI programmatically, using App Designer or using GUIDE? Have you created a callback for your slider? You should be able to update both subplots from within that callback. Please provide a sample of code that shows what you have attempted.

[Derrell Dsouza]

Please check the code below

%%
close all;
set(0,'defaultAxesFontSize',14)
set(0,'DefaultFigureWindowStyle','docked')
data = rand(3,1024,64,20); 
nslice = size(data,4);
nidx = size(data,1);

if nslice == 1
    sampling = 1; % in some of my data nslice would be 1 so I would like my slider to not give me error in such a case
else
    sampling = 5;
end 
idx = 1;
slice = 1;
h= struct;
h.f = figure(1);
x_axis = linspace(0,0.5,size(data,3));
y_axis = linspace(0,70,size(data,2));
set(h.f,'doublebuffer','on')
h.data = data;
inst_data = squeeze(data(nidx,:,:,slice));
h.ax(1) = subplot(1,2,1,'Parent',h.f,'Units','Normalized');
imagesc(h.ax(1),x_axis,y_axis, inst_data)
colorbar;
colormap(h.ax(1),'gray')
caxis(h.ax(1),[min(abs(inst_data(:))),max(abs(inst_data(:)))])
xlabel('xaxis')
ylabel('yaxis')
title('figure 1')
h.ax(2) = subplot(1,2,2,'Parent',h.f,'Units','Normalized');
log_data = log(inst_data);
imagesc(h.ax(2),x_axis,y_axis, log_data)
colorbar;
colormap(h.ax(2),'jet')
caxis(h.ax(2),[-max(abs(log_data(:))),max(abs(log_data(:)))])
xlabel('xaxis')
ylabel('yaxis')
title('figure 2')
sgtitle({'Sample data ', ['Slice: ',num2str(slice),' index: ', num2str(idx)]},'FontSize',16,'FontWeight','Bold')


h.slider1=uicontrol('Parent',h.f,...
    'Units','Normalized',...
    'Position',[0.1 0.06 0.8 0.05],...
    'Style','slider',...
    'SliderStep',[0.05,0.1],...
    'Min',1,'Max',nslice,'Value',1,...
    'Callback',{@slider_Callback,data,x_axis,y_axis});
txt1 = 'Slice';
txt2 = 'Index';
annotation('textbox', [0.05 0.07 0.05 0.04], 'string', txt1);
annotation('textbox', [0.05 0.021 0.05 0.04], 'string', txt2);

h.slider2=uicontrol('Parent',h.f,...
    'Units','Normalized',...
    'Position',[0.1 0.02 0.8 0.05],...
    'Style','slider',...
    'SliderStep',[0.50,0.50],...
    'Min',1,'Max',nidx,'Value',1,...
    'Callback',{@slider_Callback,data,x_axis,y_axis});

guidata(h.f,h)
%%
function slider_Callback(hObject,eventdata,data,x_axis,y_axis)%#ok<INUSD>
    h=guidata(hObject);%retrieve struct
    slice_i = round(get(h.slider1, 'Value'));
    idx_i = round(get(h.slider2,'Value'));
    inst  = squeeze(data(idx_i,:,slice_i));   
    colormap(h.ax(1),'gray')
    caxis(h.ax(1),[min(abs(inst(:))),max(abs(inst(:)))])
    h.ax(1) = imagesc(x_axis,y_axis,inst); colorbar
    xlabel('xaxis')
    ylabel('yaxis')
    title('figure 1')
    lg = log(inst);
    colormap(h.ax(2),'jet')
    caxis(h.ax(2),[-max(abs(lg(:))),max(abs(lg(:)))])
    h.ax(2) = imagesc(x_axis,y_axis, lg ); colorbar;
    sgtitle({'Sample data ', ['Slice: ',num2str(slice_i),' index: ', num2str(idx_i)]},'FontSize',16,'FontWeight','Bold')
    xlabel('xaxis')
    ylabel('yaxis')
    title('figure 2')
    drawnow
end





% use nested functions to add arguments to callback functions

Answer 1

[Geoff Hayes]

@Derrell Dsouza - I think the issue is with your call to imagesc where you are not specifiying the axes upon which to draw the image. In fact, the slider callback is doing the following

    h.ax(1) = imagesc(x_axis,y_axis,inst); colorbar
    % other code
    h.ax(2) = imagesc(x_axis,y_axis, lg ); colorbar;

which replaces the handles to the axes with the image object (while incorrect, because the h isn't actually updated via guidata then the axes handles are maintained for subsequent calls to this function).

The above code can be changed to specify which axes you want to update

    imagesc(h.ax(1), x_axis,y_axis,inst); colorbar
    % other code
    imagesc(h.ax(2), x_axis,y_axis, lg ); colorbar;

The above should fix the issue and so both subplots should be updated (it worked for me). I do recommend placing all of this code within a (main) function rather than using a script so that your callbacks have access to the local variables defined in the main function (like h)...this avoids the need for calls to guidata.