Hi Martin,

Thank you for your reply. I realized that the problem that I am encountering
is not because of the "aggregate" function, but the conversion between gene
symbols from my array to official symbols: I am trying to convert the gene
symbols from my array to official gene symbols using

 data.lumi.officialSymbol<-alias2SymbolTable(data.lumi.aggre.Symbol,species="Hs")

Then I replaced the gene symbols on the array with the official symbols. I
just realized that multiple gene symbols on the array were matched to the
same official symbol, which I thought was an error of the aggregate
function. I am sorry for confusing you.

Thanks,
Wendy

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