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

[Moritz Lennert]

On 05/07/09 15:13, Martin Landa wrote:
> 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.

Ok, thanks for following up on this. Should we file a bug report for the 
selection algorithm ? Could you give me more details on the problems 
with it ?

Moritz