R: How to split a specific column based on symbol in R? [duplicate]

Answer 1

One possible way is to use the function strsplit.

> clm
[1] "A+B" "B"   "A+C"
> strsplit(clm, "+")
[[1]]
[1] "A" "+" "B"

[[2]]
[1] "B"

[[3]]
[1] "A" "+" "C"

Answer 2

Like this:

df <- data.frame(drug1 = c("B+A", "B", "A+C"))
df
df$drug2 <- lapply(strsplit(as.character(df$drug1), "\\+"), "[", 2)
df$drug1 <- lapply(strsplit(as.character(df$drug1), "\\+"), "[", 1)
df

resulting

> df
  drug1 drug2
1     B     A
2     B    NA
3     A     C
>