[GRASS-stats] Loading a point-vector table with 466 columns

[Roger Bivand]

On Wed, 27 May 2009, Hamish wrote:

>
> Roger wrote:
>> Next script in R generating increasing NR and NC cases through
>> writeVECT6() to test plugin=FALSE/plugin=TRUE ratios?
>
>
> Does R have any built in profiling tools? as grass is just a collection
> of small C programs the normal ones work fine with it:

Yes, at the R level, so they won't help here. readVECT6() banches on 
plugin - if TRUE, it just calls readOGR() on the GRASS driver, if FALSE, 
it does (something like) v.out.ogr with shapefile driver to a temporary 
file and readOGR() on the shapefile. The C/C++ level code is in the 
(same) GDAL shared object for v.out.ogr and readOGR(), so I think the only 
difference is in the use or not of the plugin.

My second post (testing v.out.ogr to shapefile against ogr2ogr from GRASS 
plugin to shapefile for a many-column vector) should reveal where the 
problem is - my present feeling is that the plugin and v.out.ogr handle 
access to the GRASS vector and its attribute data differently in one way 
or another.

Roger

>
>  http://grass.osgeo.org/wiki/Bugs#Using_a_profiling_tool
>
> or use a profiling tool at the command line while running ogr2ogr with
> input=grass and output=shapefile?
>
>
> Nikos wrt your 10hr script:
> v.db.update must open and close the DB for every time you call it. That
> is very slow and inefficient. Better is to write all SQL update commands
> to a file (end each line with a ';') then use that file as input to
> db.execute so it opens the DB, updates all fields, closes DB again in
> a single step. see the db.execute man page and v.in.garmin script for an
> example (where it made a huge improvement).
>
>
>
> Hamish
>
>
>
>
>
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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