[R-sig-Geo] Normal score transformation
ashton at msu.edu
Tue Jul 8 15:00:12 CEST 2008
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:
Associate Professor ashton at msu.edu
Dept of Geography http://www.msu.edu/~ashton
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
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