Hi all, Simple question I should know: I'm unclear on the logic of why the sum of a row of a data.frame returns a valid sum but the mean of a row of a data.frame returns NA:
sum(rock[2,]) [1] 10901.05 mean(rock[2,],trim=0) [1] NA Warning message: In mean.default(rock[2, ], trim = 0) : argument is not numeric or logical: returning NA I get that rock[2,] is itself a data.frame of mode list, but why the inconsistency between functions? How can you figure this out from, e.g., ?mean ?sum Thanks in advance, Matt -- Matthew C Keller Asst. Professor of Psychology University of Colorado at Boulder www.matthewckeller.com [[alternative HTML version deleted]] ______________________________________________ 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.