Slider with non consecutive values

Hey!

My problem is: I have an object with a range of ID which are not always consecutive.

[handles.trajects{1:20,1}]

ans =

    Columns 1 through 9

      10816049    10818824    10818825    10818826    10818827    10818828    10818829    10818830    10818831

    Columns 10 through 18

      10818832    10818833    10819059    10819395    10819396    10819397    10819398    10819399    10819401

    Columns 19 through 20

      10819402    10819403

I want the user to be able to select the ID through a slider in my GUIDE GUI. This is how its setup:

    %set slider
    set(handles.slider, 'Max', max([trajects{:,1}]));
    set(handles.slider, 'Min', min([trajects{:,1}]));
    set(handles.slider, 'Value', min([trajects{:,1}]));
    handles.lastSliderValue = min([trajects{:,1}]);
    set(handles.slider, 'SliderStep', [1/(max([trajects{:,1}])-min([trajects{:,1}])) 1/20]);
    guidata(hObject,handles);

In this case the Min/Max are 10816049 and 12262539. I want the slider to go to the NEXT/PREVIOUS ID if the user clicks the arrows (SliderStep 1, diff=1) and to the NEAREST ID when the user slides to some other position. Here is the code to achieve this:

    function slider_Callback(hObject, eventdata, handles)
    disp(num2str(get(handles.slider,'Value')));
    sliderValue = get(hObject, 'Value');
    sliderValue = round(sliderValue);
    trajects = handles.trajects;
    %check if last value was 1 away
    diff = sliderValue - handles.lastSliderValue;
    if abs(diff) == 1
        %go to next flightID
        traj_idx = find([trajects{:,1}] == handles.lastSliderValue) + diff;
    else
        %calculate the nearest flightID
        [~, traj_idx] = min(abs([trajects{:,1}] - sliderValue));
    end
    set(hObject, 'Value', trajects{traj_idx,1});
    %make the selected ID in the plot...
    %...

    handles.lastSliderValue = trajects{traj_idx,1};
    guidata(hObject,handles);

    function pushbutton7_Callback(hObject, eventdata, handles)
    % hObject    handle to pushbutton7 (see GCBO)
    % eventdata  reserved - to be defined in a future version of MATLAB
    % handles    structure with handles and user data (see GUIDATA)
    disp(num2str(get(handles.slider,'Value')));

The problem is: Lets say I am on 10818824 (handles.lastSliderValue is on 10818824). Clicking the arrow left displays 10817966 and clicking right displays 10817968. It seems the slider is stuck on 10817967 internally. Checking by clicking pushbutton7 displays the correct value 10818824. I cannot seem to find the problem :(

Answer 1

[Adam]

If you have your slider values in an array then just map onto them and use the id (which is consecutive) into the array as the value in the slider. Then you can just have a min of 1, a max of 20 and index into your array of true values based on the slider value.

[Moritz H]

This worked. Thank you for that! Actually way more intuative... What a brainfart! :D It still bothers me that I could not find out the reason why matlab behaves weird in the situation above...

[Adam]

Yeah, I'm not sure exactly what was going on there, I basically jumped over it to make that suggestion as it is how I have programmed irregular sliders in the past and is much easier.