I believe that for a list as.character() applies deparse() to each element of the list. deparse() does not preserve NA-ness, as it is intended to make text that the parser can read.
> str(as.character(list(Na=NA, LglVec=c(TRUE,NA), Function=function(x){x+1}))) chr [1:3] "NA" "c(TRUE, NA)" "function (x) \n{\n x + 1\n}" Bill Dunlap TIBCO Software wdunlap tibco.com On Sat, Jan 20, 2018 at 7:43 AM, Patrick Perry <ppe...@stern.nyu.edu> wrote: > As of R Under development (unstable) (2018-01-19 r74138): > > > as.character(list(NA)) > [1] "NA" > > > is.na(as.character(list(NA))) > [1] FALSE > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > [[alternative HTML version deleted]] ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel