[BioC] Filter out pombe probeset from cerevisiae probesets for yeast2 Affymetrix chip

[Guiyuan Lei]

Hi,

Thank Marc to point out the possibility that Bioconductor annotations
to have more information about a particular field (like a gene symbol)
than Affymetrix.

As for the mask file, the Affymetrix support said that

"Only the csv annotation file is updated whereas the mask files are not.

Therefore, I would suggest you to create your own mask files that will
allow you to see only the data related to the strain of interest.

Please see the GCOS manual page 665 for details in masks, the mask is
a file containing the list of probesetIDs of interest in a txt format:
http://www.affymetrix.com/Auth/support/downloads/manuals/gcos_manual.zip
..

The probesetID can be downloaded using the annotation file
http://www.affymetrix.com/Auth/analysis/downloads/na24/ivt/Yeast_2.na24.annot.csv.zip
..
"
Cheers

Guiyuan