[BioC] Overriding maPrintTip method

[Kellie J. Archer, Ph.D.]

I have a set of custom spotted arrays that were manufactured using 
different 8 print tips, where each print tip spotted probes for 6 
subgrids. There are 12 rows and 4 columns of subgrids, with each subgrid 
containing 21 x 21 spots. After reading the data using, for  example,

>  
brain.layout<-read.marrayLayout(fname=chip7.12,ngr=12,ngc=4,nsr=21,nsc=21,skip=21211)

>  brain.gname<-read.marrayInfo(chip7.12,info.id=c(1,6),labels=6,skip=21211)

> 
brain.raw<-read.marrayRaw(chip7.12,name.Gf="ch1Intensity",name.Gb="ch1Background",name.Rf="ch2Intensity",name.Rb="ch2Background",layout=brain.layout,gnames=brain.gname,skip=21211)

I used the marrayNorm function maNorm to normalize by PrintTip, but the 
default seems to consider each subgrid as being printed by a different 
print tip (thus there are 48). How can I change the print tip assignment 
so that the actual print tip is used rather than those calculated by 
calling maPrintTip? maPrintTip does not seem to be a slot anywhere. Thanks.

Regards,
Kellie J. Archer, Ph.D.
Assistant Professor, Department of Biostatistics
Virginia Commonwealth University
1101 East Marshall Street
Richmond, VA 23298-0032
kjarcher at vcu.edu