> On Nov 18, 2015, at 5:54 PM, Richard M. Heiberger <r...@temple.edu> wrote: > > What is the rationale for the following warning in R-3.2.2? > >> is.na(expression(abcd)) > [1] FALSE > Warning message: > In is.na(expression(abcd)) : > is.na() applied to non-(list or vector) of type ‘expression’
Well, the R interpreter does think that this is not a list: > is.list(expression(abcd)) [1] FALSE > methods(is.na) [1] is.na,abIndex-method is.na,denseMatrix-method [3] is.na,indMatrix-method is.na,nsparseMatrix-method [5] is.na,nsparseVector-method is.na,sparseMatrix-method [7] is.na,sparseVector-method is.na.coxph.penalty* [9] is.na.data.frame is.na.numeric_version [11] is.na.POSIXlt is.na.raster* [13] is.na.ratetable* is.na.Surv So the rationale is probably the same as the rationale for this warning: > is.na(call("mean", 1:4)) [1] FALSE FALSE Warning message: In is.na(call("mean", 1:4)) : is.na() applied to non-(list or vector) of type ‘language' > [[alternative HTML version deleted]] I’m somewhat puzzled at your use of HTML for an Rhelp posting. I thought you were a longtime R user? ______________________________________________ > 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. David Winsemius Alameda, CA, USA ______________________________________________ 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.