[BioC] A question about PCA on microarray data

Johan Lindberg johanl at biotech.kth.se
Thu Nov 11 17:01:11 CET 2004

I have a question about principal component analysis on microarray data.
I found two functions for doing PCA, princomp and prcomp.
The calculation in prcomp is done by a singular value decomposition
which is not what I want to do.
The problem with princomp is that the function seems to scale the data
by default. Since I am dealing with log rations there is no reason to
scale the data because it is on a comparable scale. Is there some way of
doing PCA in R on microarray data without having to scale the data?
Best regards 
// Johan Lindberg 

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