Hi
Thank you gentlemen for sharing your knowledge. It makes perfect sense and using seq_along prevents errors that could be perplexing and time consuming to discover. Thank you Carl Sutton ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.