[BioC] How to get all qualified GEO Platform records in R

[Yuan Hao]

Dear List,

I want to get all the Affymetrix datasets (Human) from GEO and then  
group them according to different types of chips, like hgu133A,  
hgu133plus2, etc. so that I could know how many datasets available for  
each type of chips.

I looked at the GEOquery package in R/Bioconductor. There are a  
'manufacturer' and a 'Title' field in the GEO Platform record which  
might be useful for my purpose, but I didn't manage to figure out how  
to get all the Platform records into R workspace first. In the package  
vignette, it always deals with a single record by giving a specific  
accession number such as GPLxxxx, but how could I get all the records  
meet my criteria? Could you kindly provide some help on this? Thank  
you very much in advance!

kind regards,
Yuan