[R-sig-Geo] correlogram for categorical data

[White.Denis at epamail.epa.gov]

I have a 1000 x 1000 grid of categorical values (nine of these) and want
to compute and plot a correlogram.  Function cell2nb() will take a while
it appears but if that succeeds then can methods of sp.correlogram() be
used on categorical data?  What are "style" options in sp.correlogram()?

thanks,
Denis