[R-sig-Geo] ogr2ogr for converting postGIS layer to shapefile

[Murray Richardson]

I am not calling CGAL from R yet - currently I am just using dumping x y 
points from R to alpha shapes in a loosely coupled fashion and then 
reading the results back into R and into a postGIS database.  The alpha 
shapes is a "concave" hull routine.  I need to call the cgal C++ code 
from R and will soon work on that.  I understand it should be possible.

It would be great to have CGAL bindings in R.

Murray



G. Allegri wrote:
> Great, I didn't know it... I just made a rapid try some time ago but
> it failed because I didn't use the ""
>
> I'm sorry for bothering, how are you using R with CGAL?
>
>
> 2008/3/31, Murray Richardson <murray.richardson at utoronto.ca>:
>   
>>  See below. Haven't tried this yet.
>>
>>  Yes that is what CGAL stands for.
>>
>>  Murray
>>
>>
>>
>>
>>
>>
>>  Hi Murray,
>>
>>  Regarding the first question, you can read into R first and then output
>>  it again. You could also call ogr2ogr using a system call like:
>>
>>  system("ogr2ogr normal syntax stuff")
>>
>>  cheers,
>>  Paul
>>
>>
>>
>>  G. Allegri wrote:
>>  > Hi Murray.
>>  > About the first question. As far as I understand, you're working in R
>>  > on a *imported* PostGIS layer (I suppose you use rgdal to do it,
>>  > right?). Then you would need to export it to a shapefile (easily done
>>  > with writeOGR). Why are you considering the use of ogr2ogr? As you
>>  > probably  know, it's a binary callable from a command line, and it's
>>  > not possible (AFAIK) to do it from R...
>>  >
>>  > I dont' understand your second question...
>>  >
>>  >> Or even better could ogr be used to do this directly on a postGIS layer?
>>  >>
>>  > What do you mean?
>>  >
>>  > Giovanni
>>  >
>>  >
>>
>>     
>
>