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Release of rgdal_0.6-9

Roger Bivand 
I would like to draw the attention of users of the vector import functions 
readOGR() and ogrInfo() in the rgdal package to a number of changes in the 
0.6-9 update. In addition, users of the Windows binary rgdal package from 
CRAN (thanks to Uwe Ligges) now have functioning read drivers for GPX and 
KML vector formats.

The first user-visible change in readOGR() and friends is that instead of 
dropping DateTime, Time, and Date fields, they are now returned as 
strings, and converted into factors in the data slots of Spatial*DataFrame 
objects. If users wish to process them from there, casting first to 
character, then to a chosen R date-time class representation is now 
possible.

The second change is that NULL and empty geometries are now handled 
better. Previously, NULL geometries caused an error, while empty 
geometries (lines and polygons with no coordinates) were not detected but 
caused errors because they were invalid as Line or Polygon objects. Now 
NULL geometries are detected and skipped by default - they are reported by 
ogrInfo(). In addition, readOGR() detects empty line and polygon 
geometries, and adds then to the list og NULL geometries to skip.

These changes should mean that users who were obliged to read shapefiles 
using functions in the maptools package may now use readOGR(), with the 
remaining differences that they still need to coerce to a date-time 
representation themselves, and that the maptools functions do not (yet) 
handle empty geometries.

I'm planning to make further improvements to readOGR(), one to try to 
speed up reading data using the GRASS vector driver, another to speed up 
reading large vector data sets irrespective of driver.

Roger