Splus 8.2.0 (c. 2010) and Splus6.0 (c. 2001) act like R in this respect. x <- c(10.0, 11.0, 12.0) i <- c(FALSE,TRUE,FALSE,FALSE,TRUE) x[i] #[1] 11 NA x[i] <- 1:2 x #[1] 10 1 12 NA 2 I no longer have access to a running version of Splus 3.4, but it does not look like a feature we would have changed.
Bill Dunlap TIBCO Software wdunlap tibco.com On Sat, Sep 12, 2015 at 9:17 AM, Suharto Anggono Suharto Anggono via R-help <r-help@r-project.org> wrote: > I'll make my points clearer. > > - The case of logical index vector longer than the original vector is not > usual case for me. As I said, I encountered it in the code of function 'rank' > in R. > > - Before, I have read "S-PLUS help" (version 3.4, it seems), > http://www.uni-muenster.de/ZIV.BennoSueselbeck/s-html/helpfiles/Subscript.html. > The following is the relevant part. There are missing pieces there that I > fill by guessing. > > Vector subscripts are generated with when i and x are both vectors. (....) > The result of the expression is to extract or replace elements of x > corresponding to a vector of positive indices computed according to the value > of i. > > .... If i is logical the indices are produced by starting at 1 and selecting > the numbers for which the corresponding element is T. If is shorter than it > is extended by cyclic repetition. It can be longer than as well, with no > change in the computation of indices. .... > > .... > > For replacements, x[i] <- value the rule is that the length of will be set to > the largest value in the indices, if that is bigger than the current length > of x. .... > > > >From it, I infer that, if i is logical and length(i) >= length(x), x[i] <- > >value has the same effect to x[which(i)] <- value, where which(i) takes > >indices where i is T. > > - In R, if i is logical and length(i) > length(x), length(x) after x[i] <- > value may be different from after x[which(i)] <- value. > > - So, I wonder if R inherits the behavior from S or not. > > - The behavior is not clearly documented in R. I just find "R Language > Definition", "3.4.1 Indexing by vectors", that can be interpreted to imply > the behavior. > > - However, for a particular case, function 'rank' in R relies on the behavior. > > However, it seems that relying on the behavior is not on purpose. Previously, > at least until R 3.1.3, the code of function 'rank' has the following before > yy <- NA . > yy <- integer(length(x)) > storage.mode(yy) <- storage.mode(y) > > It seems that yy[] <- NA is what is intended. > > - However, for me, the behavior is plausible. The assumption is that indices > from 1 to length(i) exist. > > -------------------------------------- > > I think this behavior is consistent with typical indexing behaviour in R... I > would ask you what result you thought you should get? I, for one, can think > of all sorts of uses for numeric indexes that have different lengths than the > vector, but am stumped to think of any use for what you are proposing. > --------------------------------------------------------------------------- > Jeff Newmiller The ..... ..... Go Live... > DCN:<[hidden email]> Basics: ##.#. ##.#. Live Go... > Live: OO#.. Dead: OO#.. Playing > Research Engineer (Solar/Batteries O.O#. #.O#. with > /Software/Embedded Controllers) .OO#. .OO#. rocks...1k > --------------------------------------------------------------------------- > Sent from my phone. Please excuse my brevity. > > On September 5, 2015 10:02:05 AM PDT, Suharto Anggono Suharto Anggono via > R-help <[hidden email]> wrote: > >>I came across this behavior when I followed the code of function 'rank' >>in R. >> >>It seems that subassignment of a vector by a logical index vector that >>is longer than the original vector always results in expanding the >>original vector to the length of the index vector. >> >>The resulting length may be different from the result of subassignment >>by the equivalent numeric vector. For subassignment of a vector by a >>numeric index vector, the original vector is expanded to the maximum >>index, if it is larger than the length of the original vector. >> >>This is an example. >> >>> x <- NA >>> x[c(FALSE,TRUE,FALSE)] <- 1 >>> x >>[1] NA 1 NA >> >>Compare to this. >> >>> x <- NA >>> x[which(c(FALSE,TRUE,FALSE))] <- 1 >>> x >>[1] NA 1 >> >>Does S exhibit the same behavior? >> >>Currently, if there is NA and na.last = "keep", function 'rank' in R >>relies on this behavior to give correct result length. >> >>In "R Language Definition", "3.4.1 Indexing by vectors" says: "Logical. >>The indexing i should generally have the same length as x. .... If it >>is longer, then x is conceptually extended with NAs. ...." The >>statement can be taught to support the observed behavior. >> >>> sessionInfo() >>R version 3.2.2 (2015-08-14) >>Platform: i386-w64-mingw32/i386 (32-bit) >>Running under: Windows XP (build 2600) Service Pack 2 >> >>locale: >>[1] LC_COLLATE=English_United States.1252 >>[2] LC_CTYPE=English_United States.1252 >>[3] LC_MONETARY=English_United States.1252 >>[4] LC_NUMERIC=C >>[5] LC_TIME=English_United States.1252 >> >>attached base packages: >>[1] stats graphics grDevices utils datasets methods base >> >>______________________________________________ >>[hidden email] 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. > > ______________________________________________ > [hidden email] 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. > > ______________________________________________ > 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. ______________________________________________ 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.
