[BioC] A question about PCA on microarray data

[Johan Lindberg]

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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