Hello,

I'm begginer in R and in SIG also.

I try to construct a weights matrix for house sales observations using the
general weights (1/d, where d is distance between 2 observations neibourgh).
In my SIG there are some different (!) observations with the same (!)
coordinates.

To make my matrix I use the follow commandes

> dsts<-nbdists(ventes.nb, coords)
> idw<-lapply(dsts, function(x) 1/(x))
> ventes.w3<-nb2listw(ventes.nb,glist=idw, zero.policy=TRUE)

And the program retourns this message:

In nb2listw(ventes.nb, glist = idw, zero.policy = TRUE) : zero sum general
weights

I'd like to understand how the "nbdists" commande do with the neibourgh in 0
distance? Is this an appropriate commande?

Can I just ignoring the cited message?

Thanks a lot for any help

Masha Pautrel
PhD student

	[[alternative HTML version deleted]]

