x <- c(1, 1, 2, 2, 2, 3) y <- c(1, 2, 1, 3, NA, 3) > str(xyTable(x,y)) List of 3 $ x : num [1:6] 1 1 2 2 NA 3 $ y : num [1:6] 1 2 1 3 NA 3 $ number: int [1:6] 1 1 1 NA NA 1
How many (2,3)s do we have? At least one, the third entry, but the fourth entry, (2,NA), is possibly a (2,3) so we don't know and make the count NA. I suspect this is not the intended logic, but a byproduct of finding value changes in a sorted vector with the idiom x[-1]!=x[-length(x). Also the following does follow that logic: > x <- c(1, 1, 2, 2, 5, 6) > y <- c(2, 2, 2, 4, NA, 3) > str(xyTable(x,y)) List of 3 $ x : num [1:5] 1 2 2 5 6 $ y : num [1:5] 2 2 4 NA 3 $ number: int [1:5] 2 1 1 1 1 table() does not use this logic, as one NA in a vector would make all the counts NA. Should xyTable have a way to handle NAs the way table() does? -Bill On Tue, Apr 25, 2023 at 1:26 AM Viechtbauer, Wolfgang (NP) < wolfgang.viechtba...@maastrichtuniversity.nl> wrote: > Hi all, > > Posted this many years ago ( > https://stat.ethz.ch/pipermail/r-devel/2017-December/075224.html), but > either this slipped under the radar or my feeble mind is unable to > understand what xyTable() is doing here and nobody bothered to correct me. > I now stumbled again across this issue. > > x <- c(1, 1, 2, 2, 2, 3) > y <- c(1, 2, 1, 3, NA, 3) > table(x, y, useNA="always") > xyTable(x, y) > > Why does xyTable() report that there are NA instances of (2,3)? I could > understand the logic that the NA could be anything, including a 3, so the > $number value for (2,3) is therefore unknown, but then the same should > apply so (2,1), but here $number is 1, so the logic is then inconsistent. > > I stared at the xyTable code for a while and I suspect this is coming from > order() using na.last=TRUE by default, but in any case, to me the behavior > above is surprising. > > Best, > Wolfgang > > ______________________________________________ > 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
