[BioC] AffyBatch Chip Subset

[Thomas Hampton]

Using read.affy() one ends up with an AffyBatch, a complex R  
structure. If, at that point, you decide
you want to run RMA on a subset of the chips you just read in, things  
get tricky -- you are definitely
not dealing with a matrix whose columns you can simply reference at  
will.

In the past, I have dealt with this by simply starting over. This  
makes me feel like sort of an idiot.

Is there a nice way to create a modified AffyBatch containing only the  
chips I want?

Thanks.

Tom