[R-sig-Geo] Beta sp release 0.9-53 with C *Polygon* API

Roger Bivand Roger.Bivand at nhh.no
Thu Dec 17 19:35:11 CET 2009

Could I ask list participants who maintain packages depending on sp, or 
who use sp in intensive ways with *Polygon* objects to consider trying out 
the forthcoming release:

http://spatial.nhh.no/R/Devel/sp_0.9-53.tar.gz # source
http://spatial.nhh.no/R/Devel/sp_0.9-53.zip # R 2.10.1 Windows binary

and on the r-spatial sourceforge CVS repository.

The changes involve the creation of Polygon, Polygons, and SpatialPolygons 
objects in C rather than R code, and in the exposure of these C functions 
to other packages (less important for now). I see speedups of about four 
times in reading large polygon shapefiles in readOGR() in rgdal, and 
similarly in readShapeSpatial() in maptools (which remains slower), 
because the sp instantiation functions called there also call the C 
functions inside sp.

The next step is to use the C API in maptools, rgdal, and the forthcoming 
rgeos (on R-Forge).

But before releasing, I'd like to ask for reports on changes in behaviour, 
errors, etc., so that they can be addressed before the changes are 
submitted to CRAN.

The changes have been checked against the code in our book and as far as 
diff can tell (from the printed output), things look good. Running R CMD 
check with valgrind is also clean. Despite this, please treat the beta 
with appropriate caution.

Extension to *Line* objects is clearly possible and may follow soon, but 
*Polygon* were the most pressing.

Best wishes,


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

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