Dear Ken and Bill, Thanks for the comments. I obviously didn't think about the precedence issue and was unaware that one could define :=.
Best, John > -----Original Message----- > From: Kenn Konstabel [mailto:lebats...@gmail.com] > Sent: March-31-11 7:12 AM > To: William Dunlap > Cc: John Fox; Carl Witthoft; r-help@r-project.org > Subject: Re: [R] how about a "<p-" operator? > > In addition to %...% operators one can define := (I haven't seen this > possibility documented anywhere but it's used in a package) which seems to > have different precedence. > > > `:=`<-`%<-%` # the %<-% by John Fox > > a > [1] -1 > > a := 1000 + 1 > [1] 1001 > > a > [1] 1001 > > a %<-% 1000 + 1 > [1] 1001 > > a > [1] 1000 > > Regards, > Kenn > > Kenn Konstabel > National Institute for Health Development Hiiu 42 Tallinn > > On Thu, Mar 31, 2011 at 2:50 AM, William Dunlap <wdun...@tibco.com> wrote: > > The %...% operators are not a panacea. > > they have the same precedence as `*` > > and `/` (I think) so you get things like: > > > > > x %<-% 10 - 8 # %<-% has higher precedence than - > > [1] 2 > > > x # not what you thought it would be > > [1] 10 > > > > > x %<-% 10 ^3 # but lower than ^ > > [1] 1000 > > > x # this is what you expected > > [1] 1000 > > > > It isn't that hard to write a package with your own parser in it. > > Just have it generate the call tree from your input text and call > > eval() on it. > > > > Bill Dunlap > > Spotfire, TIBCO Software > > wdunlap tibco.com > > > >> -----Original Message----- > >> From: r-help-boun...@r-project.org > >> [mailto:r-help-boun...@r-project.org] On Behalf Of John Fox > >> Sent: Wednesday, March 30, 2011 4:34 PM > >> To: 'Carl Witthoft' > >> Cc: r-help@r-project.org > >> Subject: Re: [R] how about a "<p-" operator? > >> > >> Dear Carl, > >> > >> I think that the following does what you want: > >> > >> > `%<-%` <- function(e1, e2){ > >> + e1 <- deparse(substitute(e1)) > >> + env <- parent.frame() > >> + assign(e1, e2, envir=env) > >> + e2 > >> + } > >> > >> > x %<-% 10 > >> [1] 10 > >> > >> > x > >> [1] 10 > >> > >> But, as has been pointed out, it's probably easier just to > >> parenthesize the usual assignment command. > >> > >> Regards, > >> John > >> > >> -------------------------------- > >> John Fox > >> Senator William McMaster > >> Professor of Social Statistics > >> Department of Sociology > >> McMaster University > >> Hamilton, Ontario, Canada > >> http://socserv.mcmaster.ca/jfox > >> > >> > >> > >> > >> > -----Original Message----- > >> > From: r-help-boun...@r-project.org > >> [mailto:r-help-boun...@r-project.org] > >> > On Behalf Of Carl Witthoft > >> > Sent: March-30-11 7:00 PM > >> > To: r-help@r-project.org > >> > Subject: [R] how about a "<p-" operator? > >> > > >> > I was cursing Matlab again today (what else is new) because > >> the default > >> > action for every Matlab command is to spew the result to > >> the console, and > >> > one must remember to put that darn ";" at the end of every line. > >> > > >> > So I just wondered: was there ever a discussion as to > >> providing some > >> > modified version of the "<-" and "->" operators in R to do > >> the reverse? > >> > That is, since R does not print the values of a command > >> to the console, > >> > what if there were an operator such that > >> > > >> > > >> > newobject <p- somefunction() > >> > > >> > would do the same as > >> > > >> > print(newobject <- somefunction()) > >> > > >> > > >> > Any thoughts? > >> > Carl > >> > > >> > ______________________________________________ > >> > 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. > >> > >> ______________________________________________ > >> 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. > >> > > > > ______________________________________________ > > 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. > > ______________________________________________ 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.
