In R, how can I manipulate variable in dataframe using regular expression?

Question

This is the dataset

df1 <- data.frame("id" = c("ebi.ac.uk:MIAMExpress:Reporter:A-MEXP-503.100044", 
                       "ebi.ac.uk:MIAMExpress:Reporter:A-MEXP-783.100435",
                       "ebi.ac.uk:MIAMExpress:Reporter:C-DEA-783.100435"),
              "Name" = c("ABC", "DEF", ""))

The product of the dataset

                                                  id   Name
1   ebi.ac.uk:MIAMExpress:Reporter:A-MEXP-503.100044    ABC
2   ebi.ac.uk:MIAMExpress:Reporter:A-MEXP-503.100435    DEF
3   ebi.ac.uk:MIAMExpress:Reporter:A-MEXP-503.100488     

I want to make the dataframe look like this

       id     Name
1  100044      ABC
2  100435      DEF
3  100488       NA 

Can anyone show me how to approach this problem?

Answer 1

Regex way to find the last dot:

df1$id <- as.character(df1$id)
regexpr("\\.[^\\.]*$", df1$id) # may not need \\ on second one

or sapply(gregexpr("\\\\.", x), tail, 1)

Easier to remember, non-regex way:

df1$id <- as.character(df1$id)

df1$id <- sapply(strsplit(df1$id,split="\\."),tail,1)
df1$Name[df1$Name == ""] <- NA

df1

  id Name 1 100044 ABC 2 100435 DEF 3 100435 <NA> 

sapply(strsplit(df1$id,split="\\\\."),tail,1) is from here .