[R] adding an image to a plot

[Rajarshi Guha]

Hi, I'm writing code to generate a plot, in which I draw a series of  
rectangles. So my code is of the form

plot.new()
plot.window( ... )

draw rectangle
draw rectangle
...

Is there a way for me to insert a PNG or PDF graphic at a specific  
position in the plot (ideally in  plot coordinates)? I realize that  
this might probably be better done in a separate image editor, but if  
it could be done programmatically that would be very handy

Thanks,

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Rajarshi Guha  <rguha at indiana.edu>
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