[GRASS-user] i.pca vs. r.covar/m.eigensystem/r.mapcalc

[Nikos Alexandris]

On Wed, 2008-11-05 at 07:06 -0800, Dylan Beaudette wrote:
> > # trying with R
> > x <- readRAST6(c('b2','b6','b7'))
> > x.pca <- prcomp(x at data)
> >
> > Error in svd(x, nu = 0) : infinite or missing values in 'x'
> >
> >
> > ## again the same error!
> >
> > I'll try another time again.
> >
> > Kind regards, Nikos
> >
> 
> Sounds like NAs are getting in the way. This is a limitation of
> several R functions, that becomes particularly annoying when working
> with GIS data. Here are some tips on dealing with NA in GIS data:
> 
> http://casoilresource.lawr.ucdavis.edu/drupal/node/664
> 
> Cheers,
> 
> Dylan

Dylan, great info!!!

I've bombed in another wall :-(

> x.nas <- which(is.na(x at data@MOD2007_242_500_sur_refl_b02) &
is.na(x at data@MOD2007_242_500_sur_refl_b06) & is.na(x at data
$MOD2007_242_500_sur_refl_b07))
Error in which(is.na(x at data@MOD2007_242_500_sur_refl_b02) &
is.na(x at data@MOD2007_242_500_sur_refl_b06) &  : 
  trying to get slot "MOD2007_242_500_sur_refl_b02" from an object
(class "data.frame") that is not an S4 object

I am working on it. Maybe something relevant with this error in [1]

[1] https://stat.ethz.ch/pipermail/r-devel/2007-December/047743.html