Good Morning,

I need some advice on some gene expression research. I have datasets which are downloaded from GEO and customized into MS excel. I need to identify the common genes across all the datasets. I've been reading that there is a way I can use R/Bioconductor in order to simply this process but still unsure where to begin. Can anyone shed some light and guide me in the right direction? Thanks so much!

It's not clear what you mean by "customized into MS excel," but I'm imagining this means that you have gene identifiers (symbols or entrezIDs) in the first column, and data in the rest?

In any case, you'll need to load your data into R as a data.frame (you can use the readxl package (among others)) to do so.

Once you have data.frame(s) for your data, you can combine them using the merge function to combine these datasets.

If you just want iterate over the files and manually take the intersection of identifiers and such, you can use R's set operations.

It sounds like you're new to R (and programming, in general?) I'd recommend going through some R tutorials to get a feel for the language and an overview of some of its basic capabilities.