[BioC] How to read a data.frame into limma or marray

[Wolfgang Raffelsberger]

Dear list,

the question might seem trivial, I just couldn't find a function to 
transform a simple data.frame with microarray log2-ratios into a 
limma-type ot marray-type objects.
I have a data.frame containing (R/G-) log2-ratios for the each slide in 
a separate column and I 'd like to use some of the functions available 
in limma or marray, in particular to run a lowess normalization.   I 
realized that I need either limma or marray specific (S4-) objects but I 
couldn't find a function for easily creating one of these.  I guess I'll 
need either a  class 'marrayNorm'  object  or an 'MAList', but I 
couldn't find a specific function to do so. 
Or is it necessary to create an exprSet first, to be able to transform 
the data the to an MAList ?
Any suggestions ?

Just for clarification : I run R-2.6.0 with BioC 2.1

Thank's in advance,
Wolfgang
 

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Wolfgang Raffelsberger, PhD
Laboratoire de BioInformatique et Génomique Intégratives
CNRS UMR7104, IGBMC
1 rue Laurent Fries,  67404 Illkirch  Strasbourg,  France
Tel (+33) 388 65 3300         Fax (+33) 388 65 3276
wolfgang.raffelsberger at igbmc.u-strasbg.fr