[R] Projection of Shapefiles using Maptools

[Roger Bivand]

Jens Oldeland <Oldeland <at> gmx.de> writes:

> 
> Dear R-Users
> 
> I have successfully imported my Shapefile using maptools with the 
> following command lines, and I hoped that my object (nc) will be 
> recognized as projected data, so I have included the CRS command:
> 
> library(maptools)
> p4s = CRS("+proj=longlat +datum=WGS84")
> nc =  readShapePoints("D:/Projekte_INPROGRESS/Termiten/DATA/ERF_Termite.shp", 
+ proj4string=p4s)
... 
> but in the summary it tells me:
> 
...
> Is projected: FALSE
> proj4string : [+proj=longlat +datum=WGS84]
...
> 
> Is projected: FALSE ?? does this mean that it is a geographic data set 
> and not a projected or does it mean that it won´t accept my proj4string ??
> 

Your understanding of FALSE is wrong - the summary is saying that the data are 
known not to be projected, that is, they are in geographical coordinates. The 
PROJ.4 string has been used correctly.

> does anyone has an idea how to write the correct proj4string to import 
> data from UTM WGS 84 S33 ? would be nice

"+proj=utm +zone=33 +south +ellps=WGS84 +datum=WGS84"

By the way, this would have a value for "Is projected:" of TRUE, because the 
data are projected, that is not in geographical coordinates.


Roger Bivand

> 
> thank you
> JEns
> 
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