[R-sig-Geo] nb object for spatial weigths

[Roger Bivand]

On Wed, 27 May 2009, anna freni sterrantino wrote:

> Hi everyone,
> I'm a total newbie in geo, so sorry if my question is basic.
>
> Following chp 9 and chp 10  from "Applied Spatial Data Analysis with R",
> I 've got confused on how to get  from coordinates to a nb-object,
> to get to spatial weights need for modeling.
> Seems that the example at pag.245 :
>
> coords<- coordinates(Syracuse)
> IDs <- row.names(as(Syracuse, "data.frame"))
> library(tripack)
> Sy4_nb<- tri2nb(coords, row.names=IDs)
> Sy5_nb<- graph2nb(soi.graph(Sy4_nb, coords), row.names=IDs)
> Sy6_nb<- graph2nb(gabrielneigh(coords), row.names=IDs)
> Sy7_nb<- graph2nb(relativeneigh(coords), row.names=IDs)
>
> in not working anymore, due to the fact that  tri2nd has
> been deprecated; so I tried instead

I don't think that anything has happened to tri2nb(), which lives in 
spdep. If spdep wasn't loaded, you wouldn't find tri2nb() - was that the 
problem? The book code is run nightly on current R and the contributed 
packages, so I'd have expected to see any deviant behaviour already.

Roger

>
>
> tritest.tr <- tri.mesh(mydata$x,mydata$y)
> tritest.nb<- neighbours(tritest.tr)
> class(tritest.nb)
> [1] "list"
>
> how can I get tritest.tr to a nb object?
> Or there is another way ?
>
> Do I need necessarily a gal file? as I've seen in the examples.
> Thanks
>
> Anna
>
>
>
>
> >sessionInfo()
> R version 2.9.0 Patched (2009-05-03 r48460)
> i686-pc-linux-gnu
>
> locale:
> LC_CTYPE=en_US.UTF-8;LC_NUMERIC=C;LC_TIME=en_US.UTF-8;LC_COLLATE=en_US.UTF-8;LC_MONETARY=C;LC_MESSAGES=en_US.UTF-8;LC_PAPER=en_US.UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_US.UTF-8;LC_IDENTIFICATION=C
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
> other attached packages:
> [1] tripack_1.2-11  nlme_3.1-91     MASS_7.2-47     xtable_1.5-5
> [5] lattice_0.17-25 sp_0.9-36       sqldf_0-1.4     gsubfn_0.3-8
> [9]  proto_0.3-8     RSQLite_0.7-1   DBI_0.2-4       foreign_0.8-35
>
> loaded via a namespace (and not attached):
> [1] grid_2.9.0  tcltk_2.9.0 tools_2.9.0
>
>
>
>
> Anna Freni Sterrantino
> Ph.D Student
> Department of Statistics
> University of Bologna, Italy
> via Belle Arti 41, 40124 BO.
>
>
>
>
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>
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>

-- 
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