[R-sig-Geo] Importing and Handling DXF Map files in R

[Roger Bivand]

On Thu, 11 May 2006, Paolo Cavallini wrote:

> one possible way is passing through GRASS GIS (you need latest version from 
> CVS, though).
> pc

Agreed, converting from DXF through OGR (as in the rgdal package for R) is 
not possible (http://www.remotesensing.org/gdal/ogr/drv_dxfdwg.html). 
Depending on platform, there may be converters available, but not 
unemcumbered. Since the data are said to be points, I wonder if Francisco 
or the originator of the data if not him, can dump it as ASCII from the 
CAD software - since there is no topology. 

A very good book that I certainly recommend is Bailey & Gatrell's 
Interactive Spatial Data Analysis - their treatment of point pattern 
analysis is easy to follow (including kernel densities), and most of their 
point pattern examples are replicated in the examples of the splancs 
package for R. I'm not sure how kernel2d scales for 70K points, though, 
and feel that you may find the hexbin package in bioconductor an 
alternative: it is something else, but is designed for lots of data:

http://www.bioconductor.org/repository/devel/vignette/hexagon_binning.pdf

and there seems to be a smoother there too.

Please let the list know how you decide to extract the point coordinates, 
others will benefit from your experience.

Hope this helps,

Roger

> 
> At 17:09, giovedì 11 maggio 2006, Francisco Javier Aguirre Navarro has 
> probably written:
> > Hello, I am a newby in the filed of spatial data analysis, could you please
> > point me to the right libraries/functions in R  that allow me to import DXF
> > maps  and analize spatial data related to these maps ? I would appreciaiate
> > any internet references or books  that may give a good hands-on
> > introduction to spatial data analysis, I have good knowledge of classical
> > statistical methods. I need to analyze about 75000 data points scattered on
> > a map area and I'd like to construct a "density" map of my variable of
> > interest and eventually see how these densities change in time.
> >
> > Thank you very much for your help.
> >
> > Francisco J. Aguirre
> > Bavaria, Bogota -  Colombia.
> 

-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, 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