[GRASS-user] v.sample - help!

[Markus Neteler]

On Wed, Mar 25, 2009 at 11:44 PM, Richard Chirgwin
<rchirgwin at ozemail.com.au> wrote:
> OK, this is strange.
>
> I am using v.sample to determine whether a point falls inside or outside a
> simple raster (only two colors - white and brown).

Did you see
http://grass.osgeo.org/wiki/Point_in_polygon
?

> The vector points have only two columns in the table: cat, and an integer value
> (327670) - the aim is that the result will be 0 where the point is on the white
> background, and some other number when the vector is on the brown.
>
> The vector is connected to a MySQL table, and the category numbers are unique (I
> made sure of this).
>
> The error is:
>
> DBMI-MySQL driver error:
> Cannot execute:
> insert into ACT_900 values ( 3, 3.000000e+00, 3.276700e+04, 3.276400e+04  )
> Duplicate entry '3' for key 'ACT_900_cat'
>
> (v.sample has worked okay on other maps and tables so I'm completely stumped!).

I dunno but if two points fall into the same quadrant, maybe they pick the
same cat (ID) which is forbidden by the SQL unique rule?

just guessing,
Markus