[R] "autonumber" for grouping variable

Dear R users, my dataframe looks like this head(dat) Id sex byear age 1 300 m 2003 50 2 300 m 2003 36 3 402f 2003 29 4 402f 2003 21 5 402f 2003 64 6 150 m 2005 43 ... ...(where Id is just the Identification number of Individual, sex (male or female), byear (=birth

Re: [R] "autonumber" for grouping variable

say 'dat' is your data frame, then one way is the following: f <- factor(dat$Id, levels = unique(dat$Id)) dat$Number <- unclass(f) dat I hope it helps. Best, Dimitris clion wrote: Dear R users, my dataframe looks like this head(dat) Id sex byear age 1 300 m 2003 50 2 300 m 2003