[R-sig-Geo] Problem with writeOGR and overwrite_layer=T

[Roger Bivand]

On Mon, 14 May 2012, Bastien.Ferland-Raymond at mrnf.gouv.qc.ca wrote:

> Dear list,
>
> I have to produce shapefile for a coworker which uses ArcGIS and I've 
> hit a problem with the writeOGR function from the rgdal package.

I can reproduce the problem on Windows 7 with GDAL 1.9.0, that is, that 
parts of shapefiles created by OGR (the *.dbf and *.shp files) cannot be 
deleted by poDS->DeleteLayer() - line 473 in rgdal/src/ogrsource.cpp. This 
also applies before trying to overwrite them - they cannot be deleted in 
Windows Explorer either until the R session exits. Running as 
administrator does not help either.

This appears to be an interaction between Windows (7 in my case), GDAL >= 
1.8.0, which introduced bans on overwriting for Shapefiles, and possibly 
some unknown factors.

This is not a problem I can resolve, certainly not any time soon. It is 
not an R code problem as such (I believe), and the stackoverflow 
speculation is misleading, this has nothing to do with connections, only 
with Windows apparent file usage status.

I would appeal to interested Windows users to contribute a solution - you 
will need to be able to cross-compile GDAL for Windows under MSYS, and to 
build R packages. If Windows users know how to unlink files with an 
incorrect usage status without exiting R, this would possibly help, but 
doesn't get us much further.

Other GDAL/OGR uses such as ogr2ogr exit on error, but it might be helpful 
to know if ogr2ogr does the same - that is, is unable to overwrite a 
layer. MapInfo File, GML and other drivers do not seem to suffer from the 
same issue. Again, checking across a wider range of drivers would help.

Roger

>
> Here is an example:
>
> ###
>
>> library(rgdal)
> Loading required package: sp
> Geospatial Data Abstraction Library extensions to R successfully loaded
> Loaded GDAL runtime: GDAL 1.9.0, released 2011/12/29
> Path to GDAL shared files: \\sebpriv/usagers/Ferba1/R/R-2.15.0/library/rgdal/gdal
> Loaded PROJ.4 runtime: Rel. 4.7.1, 23 September 2009, [PJ_VERSION: 470]
> Path to PROJ.4 shared files: \\sebpriv/usagers/Ferba1/R/R-2.15.0/library/rgdal/proj
>> sessionInfo()
> R version 2.15.0 (2012-03-30)
> Platform: i386-pc-mingw32/i386 (32-bit)
>
> locale:
> [1] LC_COLLATE=French_Canada.1252  LC_CTYPE=French_Canada.1252    LC_MONETARY=French_Canada.1252 LC_NUMERIC=C                   LC_TIME=French_Canada.1252
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
> other attached packages:
> [1] rgdal_0.7-8 sp_0.9-98
>
> loaded via a namespace (and not attached):
> [1] grid_2.15.0    lattice_0.20-6
>> setwd("C:\\Documents and Settings\\ferba1\\Bureau\\test rgdal")
>
> # make a basic shape:
>
>> coo <- coordinates(cbind(runif(100,220000,300000),runif(100,5160000,5220000)))
>> point.shape <- SpatialPointsDataFrame(coo,data.frame(ID=paste("point",1:100,sep="_")),
> +   proj4string = CRS(" +proj=tmerc +lat_0=0 +lon_0=-73.5 +k=0.9999 +x_0=304800 +y_0=0 +datum=NAD83 +units=m +no_defs +ellps=GRS80 +towgs84=0,0,0"))
>
> # now if I try to write itm it works fine for the first 2 shapes:
>
>> writeOGR(point.shape,".","point_shape1", driver="ESRI Shapefile")
>>
>> writeOGR(point.shape,".","point_shape2", driver="ESRI Shapefile" )
>
> # but then if I try to overwrite, it fails:
>
>> writeOGR(point.shape,".","point_shape1", driver="ESRI Shapefile", overwrite_layer=T)
> Error in writeOGR(point.shape, ".", "point_shape1", driver = "ESRI Shapefile",  :
>  Creation of output file failed
>
> # Interestingly, it erases 2 files from point_shape1 before failing (the .prj and the .shx).
> # and from now on, it's impossible to create new shapefile:
>
>> writeOGR(point.shape,".","point_shape3", driver="ESRI Shapefile" )
> Error in writeOGR(point.shape, ".", "point_shape3", driver = "ESRI Shapefile") :
>  Creation of output file failed
> ###
>
> However, after restarting the whole session and erasing the files created, and try this new order:
>
> ###
>
>>
>> writeOGR(point.shape,".","point_shape1", driver="ESRI Shapefile")
>>
>> writeOGR(point.shape,".","point_shape1", driver="ESRI Shapefile", overwrite_layer=T)
>>
>> writeOGR(point.shape,".","point_shape2", driver="ESRI Shapefile" )
>>
>> writeOGR(point.shape,".","point_shape3", driver="ESRI Shapefile" )
>>
>
> ###
> Everything works fine.  So two questions arise:
>
> 1) why does overwrite_layer doesn't work when the order is changed, can it be fixed?
> 2) How to "reset" the writeOGR function after a fail as it seems once it fails, it get impossible to reuse it in the same session.
>
> After reading this post: http://stackoverflow.com/questions/6219368/problem-writing-shapefiles-with-writeogr-in-r, I think it may be some connection issue.  Is there a easy way to close manually the connection after using writeOGR?  Something like close.OGR.connection()?
>
> I know maptools::writeSpatialShape can also be used to write shapefile, however it doesn't write the projection information which I want. It seems to me that there is a problem with writeOGR, which is a good function so it could deserve to be fix.
>
> Thanks for your help,
>
> Bastien Ferland-Raymond, M.Sc. Stat., M.Sc. Biol.
> Division des orientations et projets spéciaux
> Direction des inventaires forestiers
> Ministère des Ressources naturelles et de la Faune
>
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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