Adding the argument all.x=TRUE to merge() will retain the NA values, but the only reliable way I've found to preserve order with NA values in a merge is to add an index column to x, merge the data, sort on the index column, then delete it.
Sarah On Thu, Dec 5, 2013 at 9:56 AM, Rainer M Krug <rai...@krugs.de> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Hi > > My brain is giving up on this... > > I have the following two data.frames: > > x <- data.frame(ref=c(NA, NA, NA, 10:5, NA, 1:5)) > y <- data.frame(id = c(2, 3, 4, 6, 7, 9, 8), val = 101:107) > > Which look as follow: > >> x > ref > 1 NA > 2 NA > 3 NA > 4 10 > 5 9 > 6 8 > 7 7 > 8 6 > 9 5 > 10 NA > 11 1 > 12 2 > 13 3 > 14 4 > 15 5 >> y > id val > 1 2 101 > 2 3 102 > 3 4 103 > 4 6 104 > 5 7 105 > 6 9 106 > 7 8 107 >> > > Now I want to merge y into x, but that > > a) the sort order of x stays the same (sort=FALSE in merge()) and > b) the NAs stay > > The result should look as follow (column id only here for clarity): > >> result > ref id val > 1 NA NA NA > 2 NA NA NA > 3 NA NA NA > 4 10 NA NA > 5 9 9 106 > 6 8 8 107 > 7 7 7 105 > 8 6 6 104 > 9 5 NA NA > 10 NA NA NA > 11 1 NA NA > 12 2 2 101 > 13 3 3 102 > 14 4 4 103 > 15 5 NA NA > > merge(x, y, by.x="ref", by.y="id", sort=FALSE) leaves out the NA, but > otherwise it works: > >> merge(x, y, by.x=1, by.y="id", sort=FALSE) > ref val > 1 9 106 > 2 8 107 > 3 7 105 > 4 6 104 > 5 2 101 > 6 3 102 > 7 4 103 > > Is there any way that I can tell merge() to keep the NA, or how can I > achieve what I want? > > Thanks, > > Rainer > -- Sarah Goslee http://www.functionaldiversity.org ______________________________________________ R-help@r-project.org 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.
