Recode values to a new variable using R

Question

I have a dataset with a variable that i need to change anonymise by recoding into a different variable. There are 20,000 entries, some are duplicated so my data looks something like this:

DCD97568
DCD23547
DCD27656
DCD27656
DCD87590

The end product I want is a new variable that looks like this:

DCD00001
DCD00002
DCD00003
DCD00003
DCD00004

Thanks!

Update:

I need to deal with some NA entries in the original variable and I want these to be NA in the new variable so this

DCD14579
DCD21548
NA
DCD79131
DCD79131
DCD12313

would become

DCD00001
DCD00002
NA
DCD00003
DCD00003
DCD00004

Answer 1

WE can do this with sprintf and match

df1$Col1 <- sprintf("DCD%05d", match(df1$Col1, unique(df1$Col1)))
df1$Col1
#[1] "DCD00001" "DCD00002" "DCD00003" "DCD00003" "DCD00004"

---

Or another option is factor

with(df1, sprintf("DCD%05d", as.integer(factor(Col1, levels = unique(Col1)))))

data

df1 <- structure(list(Col1 = c("DCD97568", "DCD23547", "DCD27656", "DCD27656", 
"DCD87590")), .Names = "Col1", class = "data.frame",
 row.names = c(NA, -5L))

Answer 2

Using data.table rleid , Thanks for some of the comments , Assumption here is that the data is in sequence or it can be used once the data is sorted :

x <- c("DCD97568",
       "DCD23547",
       "DCD27656",
       "DCD27656",
       "DCD87590")

new <- paste0("DCD000",data.table::rleid(x))

> new
[1] "DCD0001" "DCD0002" "DCD0003" "DCD0003"
[5] "DCD0004"