[GRASS-dev] [GRASS GIS] #1798: all relevant vector modules should have cats and where parameters

[GRASS GIS]

#1798: all relevant vector modules should have cats and where parameters
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 Reporter:  mlennert              |       Owner:  grass-dev@…              
     Type:  enhancement           |      Status:  new                      
 Priority:  normal                |   Milestone:  7.0.0                    
Component:  Vector                |     Version:  svn-trunk                
 Keywords:  where cats parameter  |    Platform:  Unspecified              
      Cpu:  Unspecified           |  
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Comment(by mmetz):

 Replying to [comment:5 hellik]:
 > Replying to [comment:4 mmetz]:
 > >
 > > IIUC, these virtual maps should behave just like normal maps: from a
 user perspective, it could look like
 > >
 {{{
 v.extract -v (-v as new flag to create a view or virtual vector)
 v.buffer
 }}}
 > >
 > > instead of
 > >
 {{{
 v.extract
 v.buffer
 }}}

 [Sorry, I meant v.extract]
 >
 > AFAIU a virtual map could be a "permanent" selection by cats/where,
 store this virtual map in the mapset and use this virtual map as input for
 processing by the v.*-modules.
 >
 >
 {{{
 v.make.virtual input=vector output=virtualmap cat=1-10 where A < 10
 v.* input=virtualmap
 }}}

 The advantage of a virtual map over using v.extract to get a "permanent"
 selection by cats/where is not clear to me because the result of v.extract
 can be processed faster than a virtual map.

 Markus M

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Ticket URL: <http://trac.osgeo.org/grass/ticket/1798#comment:6>
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