How do I set tooltip strings on scatter children?

Hello,

I am attempting to programmatically set the TooltipString property for all of the points in my scatter plot and so far have not quite gotten there.

My intention is something like:

h = scatter(xPts,yPts,'b+');
allPts = get(h,'Children');
for i=1:length(allPts)
    set(allPts{i},'TooltipString',pointNames(i));
end

... where the first get() would return the list of handles to point objects that could have individual tooltips set to their point names. I am apparently not getting the object hierarchy correct and/or am on the wrong track entirely.

Is an example of this reasonably documented?

Thanks, david

[David O]

OK, the end of this thread:

http://www.mathworks.com/matlabcentral/newsreader/view_thread/41100

has an interactive solution, but I would like to do the same within a tooltip callback.

Answer 1

[David O]

This solution is sufficient, though still using an interactive model (click button 1 to label the nearest point, button 2 to end):

          xChildren = get(get(gca,'Children'),'XData');
          yChildren = get(get(gca,'Children'),'YData');
          xAll = xChildren{3};   % In my plot, there are 3 scatter groups plotted
          yAll = yChildren{3};   % and I am interested in the elements from the 3rd.

          btn = 1;
          txtH = text(0,0,'');  % set up dummy handle at first

          maxX = max(xAll);
          maxY = max(yAll);

          XMARGIN = 0.05;
          while btn == 1,
              [xin,yin,btn]=ginput(1);
              hold on;

              % slow but not bad for our limited size data set
              mindist = 100000000;
              minItem = 0;
              for item=1:length(xAll);
                  distSq = ((xAll(item)-xin)/maxX)^2 + ((yAll(item)-yin)/maxY)^2;
                  if distSq < mindist,
                      mindist = distSq;
                      minItem = item;
                  end
              end

%            if distSq < DIST_THRESH,
                disp([biopsystrs{1,minItem} 'dist: ' num2str(distSq)]);
                delete(txtH);  % erase previous text
                txtH = text(xAll(minItem)+XMARGIN,yAll(minItem),biopsystrs{1,minItem});
%            else
%                disp(['too far: ' num2str(distSq)]);
%            end

          end   % end while button 1

Answer 2

[Walter Roberson]

scatter() does not create individual point objects.

I do not know if it is possible to set tooltipstring strings for the individual points. The only approach I can think of at the moment is to create a datacursor object and set the callback function for it to figure out which point is involved and display the appropriate string.

Answer 3

[Matt Fig]

The children of the handle to h are patch objects, which have no tooltipstring. You could do something similar to what I did here, though it would take a more work because patches don't have a position property. So you would have to translate the xdata and ydata into positions relative to the figure....