[R-sig-Geo] kriging inside borders

Roger Bivand Roger.Bivand at nhh.no
Thu May 19 19:07:14 CEST 2005

On Thu, 19 May 2005, Chloe ARCHINARD wrote:

> Hello, I'm using geoR package to compute kriging with the function
> krige.conv() and I used maptools (read.shape () + Map2poly () )  and
> splancs (borders) packages to include a object of class polylist for the
> attribute borders.

>  But I've got this message of error when 'borders' is in krige.conv () :  
> krige.conv: there are no prediction locations inside the borders.  My
> polylist is not good? The coordinates seam to be OK when I draw a map
> with this polylist object. And if I use 'borders' in the contour
> function : message error is :

> Error in as.data.frame.default(borders) : can't coerce class "polylist"
> into a data.frame

Firstly, it does help if the exact commands are given, rather than your 
choice of them. I think the main issue here is that a polylist object is a 
list of matrices with attributes, not a matrix. If your polylist object 

x <- Map2poly(read.shape("my.shp"))

what is length(x)? If it is 1, you may be able to say x[[1]] to extract 
the first matrix in the list, but even then it may not work. If you can 
show us the commands you are giving, and the length of your polylist 
object, it should be possible to find something that works. 

> If someone could help me, thanks a lot!

> Chloé Archinard

Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no

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