[R] kde on Torus

[David Winsemius]

On Jul 28, 2010, at 7:55 AM, Tim Gruene wrote:

> Hello,
>
> I have 2D-data on a torus, i.e. they are scattered within [0:2pi)  
> and are
> supposed to be periodic with period 2pi.
>
> Is there a way in R for a kernel density estimation for such data? I  
> found this
> article http://www.dmqte.unich.it/personal/dimarzio/density46.pdf
> but
> a) I don't fully understand the article (my knowledge in statistics  
> is poor)
> b) I did not understand which Eq. represents the kernel(s)
> c) I do not now R well enough to understand whether I can use kde2d  
> or nprudens
>   with an arbitrary kernel
>
> My simple-minded attempt was to extend the data to [-2pi:4pi) and  
> then use
> kde2d, but I am wondering
> a) how accurate is this
> b) is there a way to do it properly on a torus.

You could take a look at the density function within the package,  
"circular".

-- 

David Winsemius, MD
West Hartford, CT