[GRASS-stats] Speedup of readVECT6() with plugin

[Markus Neteler]

Dear Roger,

On Sat, May 31, 2008 at 5:51 PM, Roger Bivand <Roger.Bivand at nhh.no> wrote:
> On Sat, 31 May 2008, Markus Neteler wrote:
>
>> Dear Roger, all,
>>
>> I have to read in Lidar data from GRASS, so speed matters. I have
>> modified the readVECT6() function to not export to SHAPE but
>> read in directly via GRASS-GDAL/OGR plugin:
>
> Dear Markus,
>
> In theory maybe, but if I cannot make the plugin work (I use SELinux on F7
> for trials, and I have not found out how to make it accept the *.so from
> GRASS), then I don't think that it is going to be very helpful.

Sure. but I can help you if you like (got it running on various kinds of
machines). It's also documented:
http://grass.osgeo.org/wiki/Compile_and_install_GRASS_and_QGIS_with_GDAL/OGR_Plugin

My idea was: use it then it is present. That's just an additional
if condition in the code. I'll figure out how to test that (I guess that
readOGR() may know which drivers it has).

> In addition, there is only a read driver, I believe.

Right. But accelerating read in would be quite welcome.

> However, using readOGR() directly is fine, and as you show, is far superior
> to intermediate files if available.
>
> The plugin circular dependencies are a common reason for GDAL and rgdal not
> working, I'm afraid.

I am not sure about this: I have all working here, just fetching things from
CRAN. GDAL should *not* be compiled with GRASS support. Then the
GDAL-GRASS plugin doesn't interfere and is only loaded on demand
internally from GRASS when the GRASS driver is called.

Best wishes,
Markus