[R-sig-Geo] Problem with writeSpatialShape

[Roger Bivand]

On Tue, 29 Nov 2011, Sam Rabin wrote:

> Hello all. I'm trying to write a new shapefile and am running into a weird issue. After I import the new shapefile into QGIS, I can see all the polygons in the attribute table, but none of them show up on the map no matter how I play with the projections.
>
> Here is some code that isolates the problem:
> library("maptools")
> spdf_1 <- readShapePoly("original.shp")
> spdf_2 <- readShapePoly("original.shp", proj4string=CRS(as.character("+proj=utm +zone=19 +south +datum=WGS84 +units=m +no_defs")))
> writeSpatialShape(spdf_1, "output_1")
> writeSpatialShape(spdf_2, "output_2")
>
> As you can see, I tried readShapePoly with and without CRS information, 
> but both output files exhibit the same problem. I've used 
> writeSpatialShape successfully in the past, and I don't know what I'm 
> doing differently here.

The functions in maptools neither read nor write *.prj files, only *.shp, 
*.shx, and *.dbf (they use shapelib, which doesn't know about 
projections). Setting the CRS makes no difference. Did you use writeOGR() 
in rgdal before - the rgdal functions both read and write projection 
information?

Hope this helps,

Roger

>
> Thanks in advance for your help.
>
> Sam Rabin
>     Graduate student
>         Princeton University
>         Ecology & Evolutionary Biology
> 	[[alternative HTML version deleted]]
>
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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