[R-sig-Geo] save SpatialPolygonsDataFrame as dxf file

[Roger Bivand]

On Tue, 1 Dec 2015, Barry Rowlingson wrote:

> ogr2ogr on the command line does a better job. Having saved the square
> as a shapefile I can do this:
>
> $ ogr2ogr -f "DXF" output.dxf foo.shp
> ERROR 1: DXF layer does not support arbitrary field creation, field
> 'Foo' not created.

Right, thanks! Maybe gdalUtils::ogr2ogr? I got this far, but didn't check 
to see whether a file was there. So I guess writeOGR is receiving an error 
internally from the compiled code and gives up, while ogr2ogr creates the 
file and reports an error later on.

> writeOGR(p3, dsn = "square.sqlite", layer = "entities", driver="SQLite")
> library(gdalUtils)
> ogr2ogr("square.sqlite", "square.dxf", "entities", "DXF")
> dxf <- readOGR("square.dxf", "entities")

works, with the error, but the DXF file can be read by OGR - but by other 
software?

Roger



>
> - an error, but a file is created with features in it... ogrinfo tells me:
>
> $ ogrinfo -al output.dxf
> INFO: Open of `output.dxf'
>      using driver `DXF' successful.
>
> Layer name: entities
> Geometry: Unknown (any)
> Feature Count: 1
> Extent: (1.000000, 1.000000) - (2.000000, 2.000000)
> Layer SRS WKT:
> (unknown)
> Layer: String (0.0)
> SubClasses: String (0.0)
> ExtendedEntity: String (0.0)
> Linetype: String (0.0)
> EntityHandle: String (0.0)
> Text: String (0.0)
> OGRFeature(entities):0
>  Layer (String) = 0
>  SubClasses (String) = AcDbEntity:AcDbHatch
>  ExtendedEntity (String) = (null)
>  Linetype (String) = (null)
>  EntityHandle (String) = 20000
>  Text (String) = SOLID
>  Style = BRUSH(fc:#000000)
>  POLYGON ((1 1,1 2,2 2,2 1,1 1))
>
> It even reads back into R successfully:
>
> > dx = readOGR("output.dxf","entities")
> OGR data source with driver: DXF
> Source: "output.dxf", layer: "entities"
> with 1 features
> It has 6 fields
>
>
> there may be some magic incantation to writeOGR to do this, but until
> a wizard appears you might be able to get by by saving as shapefile
> (or other) and converting on the command line.
>
> Barry
>
>
> On Tue, Dec 1, 2015 at 5:41 PM, Roger Bivand <Roger.Bivand at nhh.no> wrote:
>> On Tue, 1 Dec 2015, Milan Cisty wrote:
>>
>>> Hello,
>>> I would like to save SpatialPolygonsDataFrame as dxf file. Sorry if I am
>>> doing trivial mistake, but please what is wrong on this:
>>>
>>> p = Polygon(coords = matrix(c(1,2,2,1,1,1,2,2), ncol = 2))    #this is
>>> square 1x1
>>> p1= Polygons(list(p), ID=1)
>>> p2=SpatialPolygons(list(p1))
>>> p3=SpatialPolygonsDataFrame(p2, data = as.data.frame("1"))
>>> writeOGR(p3, dsn = "square.dxf", layer = "entities", driver="DXF")
>>>
>>> and last command gave me following message:
>>> Error in writeOGR(p3, dsn = "square.dxf", layer = "entities", driver =
>>> "DXF") :
>>>  Creating Name field failed
>>> (some dxf file was produced, but it has nothing drawn in it)
>>
>>
>> No idea, nor can I find any example of how to use the file creation driver.
>> This isn't a driver in active use anywhere really. I think that the issue is
>> that DXF doesn't want attributes associated with geometries - to judge from
>> copying p3 to GRASS and writing with v.out.dxf. writeOGR needs attributes.
>>
>> Roger
>>
>>> Thanks,
>>> Milan
>>>
>>> _______________________________________________
>>> R-sig-Geo mailing list
>>> R-sig-Geo at r-project.org
>>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>>
>>
>> --
>> Roger Bivand
>> Department of Economics, Norwegian School of Economics,
>> Helleveien 30, N-5045 Bergen, Norway.
>> voice: +47 55 95 93 55; fax +47 55 95 91 00
>> e-mail: Roger.Bivand at nhh.no
>>
>> _______________________________________________
>> R-sig-Geo mailing list
>> R-sig-Geo at r-project.org
>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>

-- 
Roger Bivand
Department of Economics, Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; fax +47 55 95 91 00
e-mail: Roger.Bivand at nhh.no