[R-sig-Geo] a minor bug in rgdal?

[Roger Bivand]

On Sat, 8 Dec 2012, epaiv01 wrote:

> Dear Prof. Bivand,
>
> I am running R-2.15.2 with rgdal version 0.7-22.
> I noticed the following bug: when transforming a SpatialPoints object,
> a white space is prepended to the proj4string of the target CRS. For example:

Thanks for a helpful example. The problem has been around for a long time, 
and is basically caused by pj_get_def() in PROJ.4, which prepends a space. 
This function is called in various places in rgdal, and in addition, when 
the sp constructor method for CRS objects is called when rgdal is loaded, 
it is called then too; it checks the string for formal errors. Probably a 
forthcoming release of sp would have permitted this to be resolved at the 
R level, but in order to sort things out for earlier sp versions, I've 
added a trap in the C code in rgdal. I've committed the fix to R-forge SVN 
revision 402.

Please let me know if this helps,

Roger

>
> crds <- matrix(data=c(9.05, 48.52), ncol=2)
> spPoint <- SpatialPoints(coords=crds,
> proj4string=CRS("+proj=longlat +ellps=sphere +no_defs"))
> a <- spTransform(spPoint, CRS(paste("+proj=ob_tran +o_proj=longlat",
> "+o_lon_p=-162 +o_lat_p=39.25 +lon_0=180 +ellps=sphere +no_defs")),
> use_ob_tran=TRUE)
>
> proj4string(a)
> # " +proj=ob_tran +o_proj=longlat +o_lon_p=-162 +o_lat_p=39.25 +lon_0=180 
> +ellps=sphere +no_defs"
>
> As You can see, a white space is prepended to the proj4string, from 
> "+proj=ob_tran ..."
> it becomes " +proj=ob_tran ...". This leads to errors when one interpolates 
> using krige from gstat for example.
>
> Best regards,
>
>
>

-- 
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