[R-sig-Geo] Directional statistics and weighted mean directions

[Takatsugu Kobayashi]

R users:

This is more of a general question.

I am trying to conduct hypothesis testing about the difference of two 
angles extending from the same point. I am reading directional 
statistics by Mardia, but it seems to talk about only frequency 
distribution on the circumference drawn by the unit length vector. My 
problem involves the weighted mean direction. Weighted by which I mean 
is that the unit vectors are weighted by the frequencies attached to the 
census zones. Have anyone known good textbooks and R packages to do 
directional statistics?

Thank you very much

Taka