[R] Sequence of ordered variable to add as column

Hello all, As an example, consider the following dataframe df-data.frame(id=c(b,b,a,a,a),ord=c(2,1,1,3,2)) dates-as.Date(c(02/27/92, 02/27/92, 01/14/92, 02/28/92, 02/01/92),%m/%d/%y) df$dates-dates which was ordered with df-df[order(df$id,df$dates),] Now I would like to add a column

Re: [R] Sequence of ordered variable to add as column

Here is one way of doing it: df-data.frame(id=c(b,b,a,a,a),ord=c(2,1,1,3,2)) dates-as.Date(c(02/27/92, 02/27/92, 01/14/92, 02/28/92, + 02/01/92),%m/%d/%y) df$dates-dates df$seq - ave(as.numeric(df$dates), df$id, FUN=order) df id ord dates seq 1 b 2 1992-02-27 1 2 b 1