In R, how to get the gene symbols of a GPL (like [GPL570][1])? There is no gene symbols in the annotation for some GPL from GEO. I have lots of GPL from multi platforms. for these with no gene symbol, they have `GB_ACC`, so more specifically, how to map `GB_ACC` to gene symbol in R?

Tools like [ailun][2] can do this online or WSDL or Perl. But not in R or other language I master. Are there any other tools?

 [1]: http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GPL5717
 [2]: http://ailun.stanford.edu/platformAnnotation.php
Each GPL is provided by the submitter, so there is no "standard" approach for looking up gene symbols. You'll need to examine all the GPLs and determine what column(s) could be used for lookup.

Just a note that Bioconductor can be really useful for these mapping tasks and several (mainly Affymetrix) array platforms have corresponding Bioconductor data packages that can be used to facilitate ID mapping. A mapping from GPL to Bioconductor annotation packages is available via the GEOmetadb Bioconductor package or at this gist:

https://gist.github.com/seandavi/bc6b1b82dc65c47510c7