[GRASS-dev] [GRASS GIS] #2620: r.neighbours should offer to ignore centre value

[GRASS GIS]

#2620: r.neighbours should offer to ignore centre value
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 Reporter:  marisn        |       Owner:  grass-dev@…              
     Type:  enhancement   |      Status:  new                      
 Priority:  minor         |   Milestone:  7.0.1                    
Component:  Raster        |     Version:  7.0.0                    
 Keywords:  r.neighbours  |    Platform:  Unspecified              
      Cpu:  Unspecified   |  
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Comment(by marisn):

 Replying to [comment:2 glynn]:
 > Replying to [ticket:2620 marisn]:
 > > Currently there is not possible to ignore the centre cell when
 performing calculation in r.neighbours.
 > You can use the weight= option to supply a kernel in which the centre
 cell has zero weight.
 >
 > A flag may still be worth having if this is a sufficiently common case.
 First - it is a documentation problem as module description is "Makes each
 cell category value a function of the category values assigned to the
 cells around it" - the problem with word "around" - I read it as "nearby
 cells excluding the centre cell". I took liberty to add a notice in r64860
 that "around" means - "all surrounding cells + centre cell".

 Second - it is not possible to use weights and circular neighbourhood at
 the same time (documentation states: "The -c flag and the weights
 parameter are mutually exclusive.")

 wenzeslaus - thanks for hint. As I needed a count of neighbour cells, I
 ended with mapcalc expression "if(isnull(original), count, count-1)"

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Ticket URL: <http://trac.osgeo.org/grass/ticket/2620#comment:3>
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