[GRASS-user] Re: v.select: exact meaning of disjoint operator

[Martin Landa]

Hi,

2009/6/26 Moritz Lennert <mlennert at club.worldonline.be>:
> "disjoint - features do not spatially intersect"
>
> Which sounds pretty much like the reverse of the intersect operator.
>
> However, when I try the following in the nc_spm_06 NC data set:
>
> v.extract input=roadsmajor at PERMANENT output=cary list=1004
> v.select -g ainput=roadsmajor at PERMANENT atype=line binput=cary at user1
> btype=area output=roads_disjoint_cary operator=disjoint
>
> I get:
>
> http://geog-pc40.ulb.ac.be/grass/misc/disjoint.png
>
> whereas
>
> v.select -r -g ainput=roadsmajor at PERMANENT atype=line binput=cary at user1
> btype=area output=roads_reverse_intersect_cary operator=intersects
>
> gives me:
>
> http://geog-pc40.ulb.ac.be/grass/misc/reverse_intersect.png
>
> Is this a bug in the disjoint operator, or am I misinterpreting its meaning

It's a bug in v.select. Fixed in r38250. Currently `ope=disjoint` =
`-r operator=intersect`. It would be better to change v.select's
algorithm to select features, and to remove this ugly hack.

Martin

-- 
Martin Landa <landa.martin gmail.com> * http://gama.fsv.cvut.cz/~landa