I have some hgu133a Affymetrix GeneChip microarray data. I would like to annotate them with Ensembl gene identifiers.
I used biomaRt to annotate. However, the result still has 2239 probe sets cannot be mapped by Ensembl gene ID, such as 200026_at, 203341_at, 203877_at and so on. Does anyone also meet some problems? I will appreciate any help.
My codes are as below: