Re: [R] Creating Observation ID

" ; Subject: RE: [R] Creating Observation ID Does the following work for you? > df2 <- transform(df, ObsID=ave(rep(0,length(Group)), Group, FUN=seq_along)) > head(df2) Value Group ObsID 1 -0.0025132 B 1 2 -1.2456156 A 1 3 -2.0531704 B 2 4 1.5861770

Re: [R] Creating Observation ID

3 4 -0.2413863 A 1 5 -0.1170961 A 2 6 1.5110721 C 4 -Original Message- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of Robert Baer Sent: Tuesday, 10 May 2011 7:22 AM To: R-help@r-proje

Re: [R] Creating Observation ID

0.7197067 B 4 Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > -Original Message- > From: r-help-boun...@r-project.org > [mailto:r-help-boun...@r-project.org] On Behalf Of Robert Baer > Sent: Monday, May 09, 2011 2:22 PM > To: R-help@r-project.org > Subjec

[R] Creating Observation ID

If I have a data frame something like: Value=rnorm(30) Group = sample(c('A','B','C'), 30, replace=TRUE) df = data.frame(Value, Group) It seems like it should be simple to create an 'ObsID' column which indicates the observation order of each Value within each of the 3 groups. Somehow, I can't q