sp (version 0.9-78)

CRS-class: Class "CRS" of coordinate reference system arguments

Description

Interface class to the PROJ.4 projection system. The class is defined as an empty stub accepting value NA in the sp package. If the rgdal package is available, then the class will permit spatial data to be associated with coordinate reference systems. The arguments must be entered exactly as in the PROJ.4 documentation, in particular there cannot be any white space in += strings, and successive such strings can only be separated by blanks.

Objects from the Class

Objects can be created by calls of the form CRS("projargs"), where "projargs" is a valid string of PROJ.4 arguments. The initiation function calls the PROJ.4 library to verify the argument set against those known in the library, returning error messages where necessary. The function CRSargs() can be used to show the expanded argument list used by the PROJ.4 library.

References

http://proj.maptools.org/

Examples

if (require(rgdal)) {
  print(CRSargs(CRS("+proj=longlat +datum=NAD27")))
  print(CRSargs(CRS("+init=epsg:4267")))
  print(CRSargs(CRS("+init=epsg:26978")))
  print(CRSargs(CRS("+proj=sterea +lat_0=52.15616055555555 +lon_0=5.38763888888889 +k=0.999908 +x_0=155000 +y_0=463000 +ellps=bessel +towgs84=565.237,50.0087,465.658,-0.406857,0.350733,-1.87035,4.0812 +units=m")))
# see http://trac.osgeo.org/gdal/ticket/1987
  print(CRSargs(CRS("+init=epsg:28992")))
}