Hello, Please post questions to the Bioconductor mailing list http://bioconductor.org/help/mailing-list/ By doing this others can learn from the exchange and a larger pool of experienced users has the opportunity to respond. I've cc'd the list on this email. When you respond, please respond to all so the list is copied. As for the question, I need a reproducible example. I don't know what your data look like or what error messages you are seeing. Please provide an example and the output of typing sessionInfo() so I can see what package versions you are using. Valerie On 02/20/2013 05:29 AM, tham wen shi wrote: > Hi Valarie, > > I now facing a problem on how to transfer gene expression data into > ExpressionSet object because the gene expression data only have gene > names (example: > *AFFX-HUMISGF3A/M97935_MA_at (endogenous control)*). Others are only > gene expression data value. > > This is how I read my data. > data<-read.tabel("data.txt",header=T) > > Thanks and Regards, > Wen Shi > >