On Wed, May 11, 2011 at 8:27 AM, Emmanuel Blondel <[email protected]> wrote: > Dear all, > > I tried to use the readOGR from package rgdal to read a geoJSON file from a > Geoserver WFS. > I can get a SpatialPointDataFrame with this code: > > url<-"http://localhost:8080/geoserver/wfs?service=WFS&version=1.0.0&request=GetFeature&outputFormat=json&typeName=mylayer"; > ogrInfo(dsn=url,layer = 'OGRGeoJSON') > layer<-readOGR(dsn=url,layer = 'OGRGeoJSON') > > but my problem is regarding the attributes. I have a numeric (real) field > that is converted to integer. To see why readOGR had this behaviour, I > downloaded my geoJSON file to explore the data: It appears that the first > value for this attribute is 1, so the field is converted in integer with > readOGR, and all values between 0 and 1 are set to 0. > > Is there any way to force numeric attributes to real type?
Some experiments with the command-line ogrinfo tools seem to indicate that the geoJSON driver in OGR has this behaviour. I can't see this explicitly in the source code from a brief look, however. The JSON spec only has a single 'number' concept (no differentiating between ints and reals) so I'd argue that the geoJSON driver should read anything numeric in as 'real'. (RFC 4627). If I get five minutes today I'll create some test samples and submit a bug report to the OGR guys. A massively kludgy workaround would be to use readOGR to get the geometry, and "fromJSON" from the rjson package to get the attributes (which would need massaging to get into a data frame) - this does preserve the floating point nature of data even if the first point doesn't have a decimal point in it! If the geometry is simple enough (points?) you could do it all with fromJSON fairly easily. Final thought: Geoserver WFS should maybe generate geoJSON where real values always have a decimal point in them (I'm not sure if Geoserver is creating these from anothe data source or just passing through already-created files..). Barry _______________________________________________ R-sig-Geo mailing list [email protected] https://stat.ethz.ch/mailman/listinfo/r-sig-geo
