Thanks for the reply! I tried your suggestion, but R stops responding. Perhaps it is due to the size (>6,000 rows) of the dataset I am trying to manipulate?? -- View this message in context: http://r.789695.n4.nabble.com/Select-rows-based-on-condition-tp4562919p4563031.html Sent from the R help mailing list archive at Nabble.com.