@Kenn: Yeah I have a way of loosing concentration when fiddling around and trying to get it work. Thanks for pointing out that I supplied a third argument when I wanted an additional test in the second argument instead. Also my selection choices indeed do not make any sense, no wonder your "parser" flaked out.
@Jeff: Thanks for also pointing that out and for your tips on temporary storage and clarification on aggregation. I will have a look into plyr. Thank you both very much for your input. [[alternative HTML version deleted]] ______________________________________________ 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.