hi david---no, this time I actually know what I was asking ( ;-) ). I do need speed computed on many data sets, each of which is created by a "by" statement. so, no iterative programming on my side.
thanks, hadley for the pointer to .row_names_info() in lieu of dim() or nrows(). I don't seem to understand the second (type) argument, despite reading the docs, but all of them are giving the same answer in my data frames. so, I guess I will stick to "2" for the time being. regards, /iaw [[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.