Shapefiles don't have separate layers, and one layer can only have one geometry type (point, line, or polygon). GDAL can treat a single folder with multiple shapefiles as if each shapefile were a separate layer in a single dataset, but that is just GDAL functionality, reflecting the OGR model, and is supported by other vector formats.
I'm not very familiar with Arc? products, so I'm not 100% on this, but I think you would need to write each separate set of polygons, each with an individual depth value, to a separate shapefile and proceed from there. I don't know anything about how to get Arc to understand configurations of shapefiles, but perhaps you could use one of the other ESRI formats such as E00 (guessing here, I'll have a closer look at the OGR formats - see rgdal's ogrDrivers() for the ones available on your system). If your SpatialPolygonsDataFrame really has multiple duplicate (in X/Y) polygons with the separate depths, you can subset it for individual depths with "[" and write those out individually: e.g. depth0 <- splydf[splydf$depth == 0, ] HTH Cheers, Mike On Wed, Sep 8, 2010 at 8:07 AM, Gavin Simpson <gavin.simp...@ucl.ac.uk> wrote: > Dear List, > > Firstly, a confession: I'm not a GIS expert and I have next to no > experience of using ArcGIS or shapefiles. Apologies if anything I write > below is stupid! > > I have an ESRI ASCII grid file that I have read into R and successfully > (with the help of this list) processed it into a > SpatialPolygonsDataFrame object (via SpatialPixelsDataFrame). I have > unionised the polygons to a set of depth intervals, so all the > individual polygons associated with depths (say) between 1 and 2 m are > given the same ID; there are several depth intervals, therefore several > IDs. This is fine, and I'm happy with this, but I need to export this > object to ESRI Shapefile(s). > > I have exported the whole SpatialPolygonsDataFrame object to a single > shapefile but when my colleagues open this in ArcGIS, there is a single > layer for all depth levels and they'd like to be able to have a layer > per polygon ID. Is this possible, to write out the > SpatialPolygonsDataFrame object such that ArcGIS knows that each polygon > ID is a separate layer? > > I have worked out how to break apart the SpatialPolygonsDataFrame object > into the equivalent but with a single ID (depth interval), and have > written those out into separate shapefiles, one per depth interval, > which when loaded into ArcGIS are represented by separate layers, but > dealing with more than a few shapefiles at once is proving > "difficult" (!??!) for some, hence if it were possible to produce a > single shapefile with separate "layers" that might solve that particular > issue. > > Second Q is; is there a way to include information about how ArcGIS > displays each layer/shapefile? For example, we'd like to give each > layer/shapefile a particular fill colour, so that when loaded by a user > into ArcGIS, the particular depth polygons have a nice gradient > representing depth. Is this even remotely possible from within R, or is > this something ArcGIS does and is separate from the shapefile per se? > > Currently I am using writeOGR to read out these objects to ESRI > shapefiles. > > The reason I ask these questions is because we have a lot of these lake > bathymetries and dealing with them in ArcGIS (to get separate layers and > colour those layers accordingly) by hand is a non starter and we don't > want to start writing VB scripts in Arc at this stage. > > Thanks in advance for any pointers or suggestions you may have. And > apologies again for showing my ignorance as regards shapefiles. > > All the best, > > Gavin > > -- > %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% > Dr. Gavin Simpson [t] +44 (0)20 7679 0522 > ECRC, UCL Geography, [f] +44 (0)20 7679 0565 > Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk > Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/ > UK. WC1E 6BT. [w] http://www.freshwaters.org.uk > %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% > > _______________________________________________ > R-sig-Geo mailing list > R-sig-Geo@stat.math.ethz.ch > https://stat.ethz.ch/mailman/listinfo/r-sig-geo > -- Michael Sumner Institute for Marine and Antarctic Studies, University of Tasmania Hobart, Australia e-mail: mdsum...@gmail.com _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo
