Create an ID (row number) column

Question

I need to create a column with unique ID, basically add the row number as an own column. My current data frame looks like this:

   V1  V2
1  23  45
2  45  4         


        

Answer 1

data.table solution

Easier syntax and much faster

library(data.table)

dt <- data.table(V1=c(23, 45, 56), V2=c(45, 45, 67))

setnames(dt, c("V2", "V3")) # changing column names
dt[, V1 := .I] # Adding ID column

Answer 2

If you're starting without named rows in your df, the tidy way is:

df %>% 
  mutate(id = row_number()) %>% 
  select(id, everything())