[GRASS-dev] Re: [GRASS GIS] #1470: v.out.ascii with sql where option exports only centroids and not areas

[GRASS GIS]

#1470: v.out.ascii with sql where option exports only centroids and not areas
-------------------------+--------------------------------------------------
 Reporter:  marisn       |       Owner:  grass-dev@…              
     Type:  defect       |      Status:  new                      
 Priority:  normal       |   Milestone:  6.4.3                    
Component:  Vector       |     Version:  svn-trunk                
 Keywords:  v.out.ascii  |    Platform:  Unspecified              
      Cpu:  Unspecified  |  
-------------------------+--------------------------------------------------

Old description:

> It's not possible to export areas selected by SQL WHERE clause.
> Example from NC data set. Let's export only lake with CAT=5109:
> {{{
> v.out.ascii input=lakes at PERMANENT layer=1 output=vbuffer_fail_on_area3
> where=cat=5109 format=standard
> }}}
> Output vector part:
> {{{
> C  1 1
>  627457.82440791 231495.92575519
>  1     5109
> }}}

New description:

 It's not possible to export areas selected by SQL WHERE clause.
 Example from NC data set. Let's export only lake with CAT=5109:
 {{{ood
 v.out.ascii input=lakes at PERMANENT layer=1 output=vbuffer_fail_on_area3
 where=cat=5109 format=standard
 }}}
 Output vector part:
 {{{
 C  1 1
  627457.82440791 231495.92575519
  1     5109
 }}}

--

Comment(by martinl):

 Replying to [comment:2 mlennert]:
 > Replying to [ticket:1470 marisn]:
 > This is logicial in the sens that only the centroid has a cat=5109. No
 boundary has this cat. So this would mean implementing a specific
 algorithm to check which boundary needs to be exported together with this
 centroid.

 Basically it could be possible. Currently `v.out.ascii` opens vector map
 on level 1 (without topology). This would require level 2 (topology). I
 can imagine special flag which writes out also areas (boundaries and
 centroids), not only centroids. The problem is that boundaries of adjacent
 areas will printed twice. I am not sure whether it's a good idea to extend
 functionality of this module in this direction. Any opinion?

-- 
Ticket URL: <http://trac.osgeo.org/grass/ticket/1470#comment:3>
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