Projected data in R-Gstat

As stated on the help page for proj4string, it "Sets or retrieves
projection attributes on classes extending SpatialData". So proj4string
does not reproject. There are various ways to do projection in R but from
what you are describing maybe the simplest way for you would be to use the
package *proj4* and the commands *project* or* ptransform* from this
package. The help page for project is pasted below to give you an idea.
You may use proj4 if you like, but it does not support sp classes. For 
these, use the equivalent implementation in rgdal, see ?spTransform.

Note, however, that gstat *does* work with data in geographical 
coordinates if the data are in the form of an object of a class defined in 
sp with the coordinate reference system set - see the example to 
variogram().

Roger
Hope it helps.
Cheers

Description

Projection of lat/long coordinates or its inverse.
Usage

project(xy, proj, inverse = FALSE, degrees = TRUE, silent = FALSE,
       ellps.default="sphere")

Argumentsxy

input (list, matrix or 2d-array) - see details below.
proj

projection definition
inverse

if TRUE inverse projection is performed (from a cartographic projection
into lat/long), otherwise projects from lat/long into a cartographic
projection.
degrees

if TRUE then the lat/long data is assumed to be in degrees, otherwise in
radians
silent

if set to TRUE, warnings will be suppressed
ellps.default

default ellipsoid that will be added if no datum or ellipsoid parameter is
specified in proj. Older versions of PROJ.4 didn't require a datum (and
used sphere by default), but 4.5.0 and higher always require a datum or an
ellipsoid. Set to NA if no datum should be added to proj (e.g. if you
specify an ellipsoid directly).

On Sun, Jun 17, 2012 at 3:36 PM, Lindia99 <feimaobaobao at hotmail.com> wrote:

I am a beginner to geoStatistics and searched this thread when I have the
same trouble to project latitude and longitude data to use krige.

my location data is a n*2 matrix with colnames and 1 example below.

colnames(location)
[1] "latitude"  "longitude"

location[1,]
 latitude longitude
1 47.46947 -122.2829

and I use proj4string and get the error. How to fix this?

proj4string(location) =  "+proj=longlat +datum=WGS84"
Error in function (classes, fdef, mtable)  :
 unable to find an inherited method for function "proj4string<-", for
signature "data.frame", "character"

Thanks much!

Lindia

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Roger Bivand
Department of Economics, NHH Norwegian School of Economics,
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

Projected data in R-Gstat

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