How can I select a graph by mouse clicking and delete it?

I have five graphs in an axes in a GUI. How can I select one of the them by mouse clicking and delete it? Thanks

Answer 1

[Geoff Hayes]

azim - here is a quick and rough way to do what I think that you want. It makes several assumptions which are hopefully valid for what you are trying to do, namely that plot (or some equivalent) function is used to plot the data on the 2D axe. I've used GUIDE to mock up a GUI - it has a single axes (named axes1), a push button (named pushbutton1) to plot some data on the axes, and another button (pushbutton2) to delete the selected graphics object. The first button callback is

function pushbutton1_Callback(hObject, eventdata, handles)

% define an array of colours
colours = {'b','r','g','k','m','y'};

% is the plot handles field defined for the handles structure?
if ~isfield(handles,'plotHandles');
    handles.plotHandles = [];
end

% determine the number of handles (a maximum of six are plotted)
numHandles = mod(length(handles.plotHandles),6);

% get the x and y data for the sine wave, offset by the number of handles
x   = -2*pi:0.05:2*pi;
y   = sin(x) + numHandles;

% plot the data
h   = plot(handles.axes1,x,y,colours{numHandles+1});

% update the plot handles to the array of plot handles
handles.plotHandles = [handles.plotHandles ; h];

% save the data
guidata(hObject,handles);

The above just plots up to six sine waves on the axes. The important part is the saving of the plot graphics handle to the handles structure. This will allow us to delete the wave later on.

Now, in order to enable the user to delete a graphic object on the axes, we are going to assign a callback to the GUI/figure. In the Opening function (myGuiName_OpeningFcn), add the following code

set(hObject, ...
  'WindowButtonDownFcn',   @mouseDownCallback);

hObject is our GUI/figure, and we are going to create a callback for the mouse button down event. This callback is defined as

function mouseDownCallback(figHandle,varargin)

    % maximum distance allowed to consider a graphics object selected (arbitrary)
    DISTANCE_THRESHOLD = 2;

    % get the handles structure
    handles = guidata(figHandle);

    % get the position where the mouse button was pressed (not released)
    % within the GUI
    currentPoint = get(figHandle, 'CurrentPoint');
    x            = currentPoint(1,1);
    y            = currentPoint(1,2);

    % get the position of the axes within the GUI
    axesPos = get(handles.axes1,'Position');
    minx    = axesPos(1);
    miny    = axesPos(2);
    maxx    = minx + axesPos(3);
    maxy    = miny + axesPos(4);

    % is the mouse down event within the axes?
    if x>=minx && x<=maxx && y>=miny && y<=maxy 

        % do we have graphics objects?
        if isfield(handles,'plotHandles')

            % get the position of the mouse down event within the axes
            currentPoint = get(handles.axes1, 'CurrentPoint');
            x            = currentPoint(2,1);
            y            = currentPoint(2,2);

            % we are going to use the x and y data for each graphic object
            % and determine which one is closest to the mouse down event
            minDist      = Inf;
            minHndlIdx   = 0;

           for k=1:length(handles.plotHandles)
               xData = get(handles.plotHandles(k),'XData');
               yData = get(handles.plotHandles(k),'YData');
               dist  = min((xData-x).^2+(yData-y).^2); 

               if dist<minDist && dist<DISTANCE_THRESHOLD
                   minHndlIdx = k;
                   minDist = dist;
               end
           end

           % if we have a graphics handle that is close to the mouse down
           % event/position, then save its index into the plotHandles array
           if minHndlIdx~=0
               handles.graphicToDeleteHandleIdx = minHndlIdx;
           else
               handles.graphicToDeleteHandleIdx = [];
           end

           % change the line style of the selected object
           for k=1:length(handles.plotHandles)
               if k==minHndlIdx
                   set(handles.plotHandles(k),'LineStyle',':');
               else
                   set(handles.plotHandles(k),'LineStyle','-');
               end
           end

           guidata(figHandle,handles);
        end
    end

The above is fairly straightforward - we take the position where the user has pressed within the axes and try to find the closest graphics object to this position. If found, then se save its index within the plotHandles array to the handles object so that we can access this index within the delete button callback which is defined as

function pushbutton2_Callback(hObject, eventdata, handles)

 if isfield(handles,'graphicToDeleteHandleIdx') && ~isempty(handles.graphicToDeleteHandleIdx)
      % delete the graphics object
      delete(handles.plotHandles(handles.graphicToDeleteHandleIdx)); 

      % remove the graphics object from the array of plot handles
      handles.plotHandles(handles.graphicToDeleteHandleIdx) = [];

      % clear the handle
      handles.graphicToDeleteHandleIdx = [];

      % save the data
      guidata(hObject,handles);
 end

I've attached the code for this example. Hope it helps!

[azim]

Dear Geoff Hayes, Thank you for your complete response. It was very helpful. Regards

[Geoff Hayes]

azim's answer moved here

Dear Geoff Hayes, Thank you for your complete response. It was very helpful. Regards

Answer 2

[Nick Counts]

If you need to do it programmatically, Geoff seems to have nailed it.

If you are using any of Matlab's built-in toolbar items on your figure, then you actually have the controls built into your GUI already! Either:

1. Just select the "Edit Plot" tool (which looks like a regular mouse cursor)Then you can either regular-click on an item and press delete (maybe Backspace for a Windows user) or
2. Right-click on a graphics object and select "Delete" from the context menu that pops up!