r - Remove part of string after "."

Question

I am working with NCBI Reference Sequence accession numbers like variable a:

a <- c("NM_020506.1","NM_020519.1","NM_001030297.2","NM_010281.2","NM_011419.3", "NM_053155.2")  

To get information from the biomart package I need to remove the .1, .2 etc. after the accession numbers. I normally do this with this code:

b <- sub("..*", "", a)

# [1] "" "" "" "" "" ""

But as you can see, this isn't the correct way for this variable. Can anyone help me with this?

Answer 1

You just need to escape the period:

a <- c("NM_020506.1","NM_020519.1","NM_001030297.2","NM_010281.2","NM_011419.3", "NM_053155.2")

gsub("\..*","",a)
[1] "NM_020506"    "NM_020519"    "NM_001030297" "NM_010281"    "NM_011419"    "NM_053155"