Renaming duplicate strings in R

Question

I have an R dataframe that has two columns of strings. In one of the columns (say, Column1) there are duplicate values. I need to relabel that column so that it would have t

Answer 1

Let's say your data (ordered by Column1) is within an object called tab. First create a run length object

c1.rle <- rle(tab$Column1)
c1.rle
##lengths: int [1:4] 2 2 1 1
##values : int [1:4] 1 2 3 4

That gives you values of Column1 and the according number of appearences of each element. Then use that information to create the new column with unique identifiers:

tab$Column1.new <- paste0(rep(c1.rle$values, times = c1.rle$lengths), "_",
        unlist(lapply(c1.rle$lengths, seq_len)))

Not sure, if this is appropriate in your situation, but you could also just paste together Column1 and Column2, to create an unique identifier...