[R-sig-Geo] Projected data in R-Gstat

[Roger Bivand]

On Mon, 18 Jun 2012, kapo coulibaly wrote:

> 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
>>
>>
>> --
>> View this message in context:
>> http://r-sig-geo.2731867.n2.nabble.com/Projected-data-in-R-Gstat-tp7549970p7580233.html
>> Sent from the R-sig-geo mailing list archive at Nabble.com.
>>
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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