[BioC] calculating replicate average in exprs(eset)

[Georg Otto]

Hi,

I have a problem with an exprSet, that consists of 16 samples with 2
replicates each, i.e. 32 arrays.

Using
> exprs(eset)

I get the expression values for each gene in each array, with the two
replicates as adjacent columns, like this:

A1 A2 B1 B2 C1 C2 D1 D2 ...

I would like to calculate the mean of the two replicates for each gene
and generare a matrix of the mean values. How can I do this?

Likewise, using

>Calls<-mas5calls(AffyBatch)
>exprs(Calls)

I get a data frame with mas5 calls (P, A, or M). I would like to test,
if the calls for the two replicates are the same and return the call
to a data frame, otherwise return NA. Any idea how to do this?

Your help will be highly appreciated!

Georg