[R-sig-Geo] ArcGIS/R data exchange

[Roger Bivand]

On Tue, 14 Jun 2005, Christof Bigler wrote:

> I would like to get some feedback on data exchange between ArcGIS and R 
> (both directions) under Windows. I noted that StatConnector can be used 
> to directly connect ArcGIS with R, and probably the R packages 
> "shapefiles" and "maptools" might be used for reading and writing ESRI 
> shapefiles.  Are these seamless procedures for the import and export of 
> different data types (grid, points, polygons)?

Seamless is just a touch optimistic. The most advanced project is for 
doing point pattern analysis from Arc using R/splancs in the background. 
But the code for that is still being worked on by the authors, who have 
spent a lot of time making point pattern techniques "look and feel" like 
Arc through VBA. 

> There's also the newly developed R package "sp" which might get the 
> standard tool for exchanging spatial data. Is this package mostly 
> intended for the exchange of different formats of spatial data within R 
> or is there a possibility to import data from and export to ArcGIS?

Yes, but loosely coupled, reading and writing files. Indeed, sp provides 
containers for data objects, and small wrapper packages are available for 
maptools and rgdal, for example. But seamless is not practical except in 
regular production settings, in research, too much changes across data 
sets to make full tight coupling worth the effort (especially with cheap 
fast processors and lots of memory and disk storage), temporary files at 
least let you look at the mess while it is in transit if debugging is 
needed.

> In R, I plan to work with the packages "spdep" and "nlme" for lattice 
> data and "spatstat" for point patterns.
> 

It would be helpful to have input on how the sp classes match your data 
object needs, and which kinds of data need to go in which direction. The 
sp package fully supports PROJ.4, but so far we haven't got the read-write 
functions to mesh with Arc - not much to do, but it needs doing. All the 
sp things are on the sourceforge site found in the CRAN Spatial Task View.

Best wishes,

Roger


> Any advice is appreciated.
> 
> Christof
> 
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-- 
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