Thank you very much for your code. I am looking for a method to do normal
score transform on raster data, and I will try your code.
For the moment I am not interested in the back transformation , but it could
be useful for the future.

I am sorry if the topic was already considered in the pas, but
unfortunately  I have some problems in searching on the R-sig-geo mailing
list.

Thank you very much

Laura

2008/7/8 Ashton Shortridge <ashton@msu.edu>:

> Hi Laura,
>
> I've written code to do normal score and back-transforms. Edzer dropped
> this
> code from me last month on this list, but I'll repost.
>
> Normalizing data is extremely simple in R. The back-transform is the
> problematic part. Please read the documentation in the file to learn more
> about these issues and to help determine if what I wrote is useful for you.
>
> The URL for the normal score code is:
> http://www.msu.edu/~ashton/temp/nscore.R<http://www.msu.edu/%7Eashton/temp/nscore.R>
>
> Yours,
>
> Ashton
>
> --
> Ashton Shortridge
> Associate Professor                     ashton@msu.edu
> Dept of Geography                       http://www.msu.edu/~ashton<http://www.msu.edu/%7Eashton>
> 235 Geography Building          ph (517) 432-3561
> Michigan State University               fx (517) 432-1671
>
> On Tuesday 08 July 2008, Laura Poggio wrote:
> > Dear all,
> > I have a small image with three bands and I would like to normalise the
> > variance of the three bands in order to get a more homogeneous dataset
> for
> > further elaborations.
> > I am thinking to use the normal score transform, but I have some
> questions
> > about how to implement in R and especially how to do with raster data.
> > My data are read into R with the readGDAL function.
> >
> > I have been trying the qnorm() and the qqnorm(ppoints()) with strange
> > results, using on data.frame or matrix or vector types: in any case all
> > values are NAs.
> >
> > Any suggestion on which is the most suitable function to do the transform
> > on raster data within R would be really appreciated.
> >
> > Thank you very much in advance
> >
> > Laura
> >
> >       [[alternative HTML version deleted]]
> >
> > _______________________________________________
> > R-sig-Geo mailing list
> > R-sig-Geo@stat.math.ethz.ch
> > https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>
>
>

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