[R] Testing for blank space in a plot

[John Fort]

   I have written code which puts text to the upper right of points on  
a plot.  Some of my point are very close together and the new text is  
writing over the previous text.

   Has anyone written a clever "smart-text" function that writes the  
text in a blank spot near the point (perhaps on the lower left or  
lower right side) when it discovers that the new space is not blank.

  I could write such a function if there was an is.blank(x,y) command.  
  Does something like that exist?

  Thanks.