[R-sig-Geo] spTransform() error : "load package rgdal for spTransform methods"

[Roger Bivand]

On Wed, 6 Aug 2014, Remi Genevest wrote:

> Hi,
> I am facing a recurrent problem associated with spTransform() function from
> rgdal package.
> While I try to change the CRS of a SpatialGrid, I get the following error :
>
> Error in spTransform(grd, CRS("+init=epsg:3857")) :
>  load package rgdal for spTransform methods

Thanks for the example. You cannot use spTransform on SpatialGrid objects 
- this is known as warping, and does not return a regular grid in general. 
You can do:

grd<-spTransform(as(grd, "SpatialPoints"), CRS("+init=epsg:3857"))

but:

gridded(grd) <- TRUE
#suggested tolerance minimum: 0.223608
#Error in points2grid(points, tolerance, round) :
#  dimension 2 : coordinate intervals are not constant

Try warping instead.

Hope this clarifies,

Roger

>
> Does anybody know how to solve it?
>
> Here is my code :
>
>> library(rgdal)
>> # create the SpatialGrid
>> cc<-c(10,20)
>> cs<-c(0.1,0.1)
>> cd<-c(200,200)
>> grd<-GridTopology(cellcentre.offset=cc,cellsize=cs,cells.dim=cd)
>> grd<-SpatialGrid(grd)
>> # set the CRS :
>> proj4string(grd)<-CRS("+proj=longlat +datum=WGS84")
>> # transform the CRS :
>> grd<-spTransform(grd,CRS("+init=epsg:3857"))
> Error in spTransform(grd, CRS("+init=epsg:3857")) :
>  load package rgdal for spTransform methods
>>
>> ###################################################### R info session
>> sessionInfo()
> R version 3.1.1 (2014-07-10)
> Platform: x86_64-pc-linux-gnu (64-bit)
>
> locale:
> [1] LC_CTYPE=en_GB.UTF-8       LC_NUMERIC=C
> LC_TIME=en_GB.UTF-8        LC_COLLATE=en_GB.UTF-8
> LC_MONETARY=en_GB.UTF-8
> [6] LC_MESSAGES=en_GB.UTF-8    LC_PAPER=en_GB.UTF-8       LC_NAME=C
> LC_ADDRESS=C               LC_TELEPHONE=C
> [11] LC_MEASUREMENT=en_GB.UTF-8 LC_IDENTIFICATION=C
>
> attached base packages:
> [1] grid      stats     graphics  grDevices utils     datasets  methods
> base
>
> other attached packages:
> [1] rgdal_0.8-16    raster_2.2-31   hexbin_1.26.3   lattice_0.20-29
> sp_1.0-15
>
> loaded via a namespace (and not attached):
> [1] colorspace_1.2-4 digest_0.6.4     ggplot2_1.0.0    gtable_0.1.2
> MASS_7.3-33      munsell_0.4.2    plyr_1.8.1       proto_0.3-10
> Rcpp_0.11.2
> [10] reshape2_1.4     scales_0.2.4     stringr_0.6.2    tools_3.1.1
>
>
>
> --
> View this message in context: http://r-sig-geo.2731867.n2.nabble.com/spTransform-error-load-package-rgdal-for-spTransform-methods-tp7586877.html
> Sent from the R-sig-geo mailing list archive at Nabble.com.
>
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-- 
Roger Bivand
Department of Economics, Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; fax +47 55 95 91 00
e-mail: Roger.Bivand at nhh.no