Hi to everyone,

Thanks to all of you for the advice on this, which has solved my problem
quite nicely now.  Based on your suggestions, I figured out the following:

ogr2ogr was broken for me because I had not completely removed a prior
custom install of gdal that I had set up for hdf4 support, which required
libjpeg. Once removed, I can use ogr2ogr fine from the linux shell.

Since I want to select a particular record from the postgis database, and
want to keep the object in R without writing it to disk for the time being
(which would rule out a system call to ogr2ogr as an option), I am using
the RpostgreSQL option together with rgeos::readWKT.  I am basing this on
the idea that it is not possible to use sql statements in readOGR, and thus
can't select an individual geometry from a table (although I see there was
some talk about this in 2010:
http://r-sig-geo.2731867.n2.nabble.com/passing-SQL-through-readOGR-td3816889.html).


library(RPostgreSQL)
# CRS
drv <- dbDriver("PostgreSQL")
con <- dbConnect(drv, dbname = "mydb", user = "me", password = "mypw")
sql <- "SELECT ST_AsEWKT(geom) from sa1kgrid where id=9"
kmlGeom <- dbGetQuery(con, sql)
kmlGeom
1 SRID=97490;MULTIPOLYGON(((570779.01553729
-2401338.07340772,571779.01553729 -2401338.07340772,571779.01553729
-2402338.07340772,570779.01553729 -2402338.07340772,570779.01553729
-2401338.07340772)))
# Comes back as data.frame with SRID, which needs to be stripped out for
readWKT to work
geomStr <- unlist(strsplit(kmlGeom[1, ], ";"))
geomPoly <- readWKT(geomStr[-grep("SRID", geomStr)])

That seems to work nicely, so thanks for the solution!

Best, Lyndon





On Tue, Oct 9, 2012 at 5:21 PM, Edzer Pebesma <edzer.pebesma@uni-muenster.de
> wrote:

>
>
> On 10/09/2012 12:04 PM, Barry Rowlingson wrote:
> > There must be an R WKT reader somewhere...
>
> rgeos::readWKT
> --
> Edzer Pebesma
> Institute for Geoinformatics (ifgi), University of Münster
> Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251
> 8333081, Fax: +49 251 8339763  http://ifgi.uni-muenster.de
> http://www.52north.org/geostatistics      e.pebesma@wwu.de
>
> _______________________________________________
> R-sig-Geo mailing list
> R-sig-Geo@r-project.org
> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>

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