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