Question

I have a cell array of strings (which is actually a list of files selected by the user). I would then like to bring up a user interface control that allows the user to manually reorder that list.

Essentially I would like the user to be able to select the order in which the files given are processed. Is there a piece of code already that does this or does anybody have any good suggestions for how to do this?

Ideally it would show the list of strings (file names) and you could click on one and click an up or down arrow to move it up or down in the list, or for bonus points 😛 it would allow for dragging them to reorder (though I doubt such a thing exists for matlab GUI).

Answer 1

There’s no native support for this in Matlab. The easiest solution is to use a uitable with “some hacks”.

The solution shown below works for selection of single cell in the table, or multiple cells. Bounds are maintained, i.e., values do not “wrap around”.

function reorderableTable

    h(1) = figure(1); clf

    filenames = {...
        'file1.txt.'
        'file2.txt.'
        'file3.txt.'
        'file4.txt.'
        'file5.txt.'
        };

    h(2) = uitable(h(1),...
        'data'    , filenames, ...
        'units'   , 'normalized',...
        'position', [0.1 0.1 0.5 0.85],...
        'CellSelectionCallback', @selectCells);

    h(3) = uicontrol(...
        'style'   , 'pushbutton', ...
        'units'   , 'normalized',...
        'position', [0.7 0.58 0.2 0.15],...
        'string'  , 'Up',...
        'callback', @reOrder);
    h(4) = uicontrol(...
        'style'   , 'pushbutton', ...
        'units'   , 'normalized',...
        'position', [0.7 0.38 0.2 0.15],...
        'string'  , 'Down',...
        'callback', @reOrder);

    set(h(3:4), 'enable', 'off');

    function selectCells(src, evt)
        set(src, 'UserData', evt.Indices);
        if ~isempty(evt.Indices)
            set(h(3:4), 'enable', 'on');
        else
            set(h(3:4), 'enable', 'off');
        end
    end

    function reOrder(src,~)

        up = strcmpi(get(src, 'string'), 'up');

        table = h(2);
        data = get(table, 'Data');
        selected = get(table, 'UserData');        
        selected = selected(:,1);

        if up

            sel  = selected-1;
            not_selected = setdiff(sel, selected);            
            nsel = setdiff(selected, sel);

            if sel(1)>=1 && nsel(end)<=size(data,1)
                new_data = data;
                new_data(sel ,:) = data(selected,:);
                new_data(nsel,:) = data(not_selected,:);            
            else
                return
            end   

        else
            sel  = selected+1;
            not_selected = setdiff(sel, selected);            
            nsel = setdiff(selected, sel);          

            if sel(1)<=size(data,1) && nsel(end)>=1
                new_data = data;
                new_data(sel ,:) = data(selected,:);
                new_data(nsel,:) = data(not_selected,:);                
            else
                return
            end

        end

        set(table, 'Data', new_data);
    end
end

Inspiration (partly) came from here.

If you don’t like nested functions it’s easy to redefine them as subfunctions, but then you’ll have to pass the handles around (which is why I opted to use nested functions in the first place).

Dragging-and-dropping: it can be done natively, but only on uitable columns (see this link). This I think will look horrendous, but might just work if you only have one or two files.

Otherwise: you can use the buttons as shown above, or google around a bit to see if there is some other Java object (other than jTable) that does allow you to drag rows about. I’m not intimately familiar with Java, so you’ll have to look elsewhere.