On Tue, 14 Nov 2006, Weiwei Shi wrote: > Hi, > I am writing a generic function and need to check if an arg is a data > frame or not.
?is.data.frame > I could use is.null(dim(x)) to get what i want. In which case you would fail. Arrays and many other objects have non-NULL dims. > But i want to know if there is a > function which can tell me whether it is a list, a numeric vector, a > data frame, a factor and so on. Can R do that? Yes. ?typeof, ?class, ?str, ?inherits ... and please do study 'An Introduction to R' (belatedly). You do seem to be asking almost daily for people to read the documentation for you. Please try install.packages("fortunes"); library(fortunes); fortune("WTFM") -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ R-help@stat.math.ethz.ch 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.