Hi members, I'd like to thank you guys ahead of time for the help. I'm kind of stuck.
I have a data frame with ID and position numbers: 1> head(failed.3) id position 1 10000997 2 4 1000RW_M 2 15 1006RW_G 2 24 1012RW_M 3 28 10160917 2 30 1016RW_M 13 I'd like to use this to subset out a large dataset and keep only the observation number corresponding to the position number. So for example, ID 10000997 has 10 observations. I want to keep the 2nd one only. Thanks, -linh ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.