R: How to overlay pie charts on 'dots' in a scatterplot in R

Question

Using R I would like to replace the points in a 2d scatter plot by a pie chart displaying additional values.

The rational behind is that I have time series data for

Answer 1

See also Paul Murrell. Integrating grid graphics output with base graphics output. R News, 3(2):7-12, October 2003. http://www.r-project.org/doc/Rnews/Rnews_2003-2.pdf

The code on pp 10-11 sets up the main plot axes, labels and legend, and then opens a series of smaller windows centered at each individual point on the plot and plots a small graph in each window. I've tried pie charts, mosaics and barplots, but the method is not limited to these types.