[GRASS-dev] Re: [GRASS GIS] #576: i.pca fails to center data prior to analysis

GRASS GIS trac at osgeo.org
Fri Nov 4 09:43:25 EDT 2011

#576: i.pca fails to center data prior to analysis
 Reporter:  nikos                                             |       Owner:  grass-dev@…              
     Type:  defect                                            |      Status:  new                      
 Priority:  normal                                            |   Milestone:  6.5.0                    
Component:  Raster                                            |     Version:  svn-develbranch6         
 Keywords:  i.pca, data centering, prcomp(), R, eigenvectors  |    Platform:  Unspecified              
      Cpu:  Unspecified                                       |  

Comment(by mmetz):

 Replying to [comment:1 mmetz]:
 > I get identical results with i.pca in trunk r49090 if I create a MASK
 first, thus excluding any NULL cells (some cells are NULL in one band but
 not NULL in another band).

 Calculating a MASK in order to get results identical to ''prcomp(x,
 center=TRUE, scale=FALSE)'' is no longer needed as of r49092.

 Markus M

Ticket URL: <https://trac.osgeo.org/grass/ticket/576#comment:2>
GRASS GIS <http://grass.osgeo.org>

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