> On Dec 17, 2016, at 11:34 AM, Bert Gunter <bgunter.4...@gmail.com> wrote: > > It's documented, David: > > From ?"[.data.frame" > > "Matrix indexing (x[i] with a logical or a 2-column integer matrix i) > using [ is not recommended. For extraction, x is first coerced to a > matrix..." > > ergo characters for a mixed mode frame.
Can we agree that it is most ironic that `[<-.data.frame` does not impose coercion on its `x` argument with a 2 column matrix as `i`, but that `[.data.frame` does? I had initially assumed that the coercion had occurred at the time of assignment which would have made more sense (to me, anyway). -- David. > > Cheers, > Bert > > > Bert Gunter > > "The trouble with having an open mind is that people keep coming along > and sticking things into it." > -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) > > > On Sat, Dec 17, 2016 at 10:49 AM, David Winsemius > <dwinsem...@comcast.net> wrote: >> This puzzle started with an SO posting where the questioner showed output >> from a dataframe that had been indexed with a matrix. The output appeared to >> show that numeric values had been coerced to character. Once I got a >> reproducible example I discovered that the print output was the problem and >> that the actual values had not been coerced. I've created a much smaller >> test case and it appears from the testing below that a matrix indexed output >> from a dataframe with mixed numeric and character types will be printed as >> character even if none of the values indexed are character: >> >>> dat <- setNames( as.data.frame( matrix(1:12, ncol=4) ), LETTERS[1:4]) >>> dat >> A B C D >> 1 1 4 7 10 >> 2 2 5 8 11 >> 3 3 6 9 12 >>> dat[2,4]<-NA >>> dat[3,3]<-NA >>> ng <- which(is.na(dat), arr.ind=TRUE) >>> ng >> row col >> [1,] 3 3 >> [2,] 2 4 >>> dat[ng] <- 20 >>> dat[ng] >> [1] 20 20 >> >> That was as expected. Now repeat the process with a dataframe of mixed types. >> >>> dat[2,4]<-NA >>> dat[3,3]<-NA >>> dat[,1]<- "a" >>> dat >> A B C D >> 1 a 4 7 10 >> 2 a 5 8 NA >> 3 a 6 NA 12 >>> dat[ng] <- 20 >>> dat[ng] >> [1] "20" "20" >> >> Quoted print output was not what I was expecting. >> >> -- >> >> 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. 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.
