[R] about the char _

Fan xiao.gang.fan1 at libertysurf.fr
Fri Oct 5 21:47:53 CEST 2001


1. I totally agree with the idea of maintaining back compatibility,
my question was: "is there an option to change this behaviour"
(locally or globally). An option will be the only way to satisfy everyone.

2. I'm little surprised of the discussions followed in this thread:
my question was not a theoritical langugage concern (like the operator
assignment, lazeiness, etc.), or a conversion feasability (like make.names, 
use of ""), but rather the following issue:
  "how to maintain the same variable names in different systems"

--
Fan

ps: the origin of the assignment in S comed from APL, 
the first array or vector oriented language.

Frank E Harrell Jr wrote :
> I have to agree with Laurent.  I don't think this is a
> big issue.  I've been importing SAS datasets into S
> for 10 years and have not ever been disappointed to
> see a period instead of an underscore in a variable
> name.
> 
> In addition it is very important to maintain compatibility
> with S-Plus on this issue.
> 
> Users of ESS under Emacs can be lazy and politically
> correct also as _ is immediately expanded to <-
> 
> Frank
> 
> Laurent Gautier wrote:
> >
> > I do not want to pour oil on fire (see the "S-Plus != R" earlier this
> > week).
> > (I am writing in peace. =)  )
> >
> > I do not see the 'underscore' thing as a _major_ issue.
> >
> > If one really really really want to have underscores, one still can:
> >
> > > "underscore_if_I_want" <- 2
> > > get("underscore_if_I_want")
> > [1] 2
> >
> > Regards,
> >
> > Laurent
> >
> > Philippe Grosjean wrote:
> > >
> > > >Dear all,
> > >
> > > >I don't know the historical reason why the char '_' was
> > > >defined in the R language grammar as a synonyme of the
> > > >assignment <-, anyway the R documentation dosen't recommand
> > > >its usage.
> > >
> > > >Well, this is a real "incompatibility issue" each time
> > > >we need to interface R with other language/systems, notably with
> > > >database systems. Recall that, in perhaps all computer systems,
> > > >the char '_' can be used in the name of a variable or a column
> > > >in a data table.
> > >
> > > >So that's my question : is there an option to change this
> > > >behaviour ?
> > >
> > > >All that I want is the possibility to use the same name of
> > > >variables in my R source as they are declared in the other systems.
> > >
> > > >Thanks
> > > >--
> > > >Fan
> > >
> > > I totally agree with this. Since _ is a deprecated synonym of <-, is it any
> > > possibility to eliminate it in one of the next major versions of R?
> > > Therefore, a variable name like my_variable would become viable... like in
> > > most other computer languages. What I really appreciate in R synthax is that
> > > there is almost no ambiguities. I mean, in R, a word has only one
> > > signification. For instance <- is assignation, = gives a value to an
> > > argument in a function and == is for comparison, where some other languages
> > > use the same = in the different situations. As far as I know, there are only
> > > two cases where the same word (or character) can be used in two different
> > > situations:
> > > 1) A function, and an argument in a function can both have the same name,
> > > i.e., myfunction <- function(myfunction="value", arg2,...) {} is viable;
> > > 2) The dot is used both in variable names and to represent the object
> > > hierarchy: my.var and print.myvar. The first dot is part of the variable
> > > name, while the second dot separate the method (print) and the variable
> > > (myvar). If _ was allowed in variables names, we could use print.my_var
> > > (which should, perhaps, be recommended) and it would be easier to spot where
> > > is the "object hierarchy" and where is the variable name.
> > > Best,
> > >
> > > Philippe Grosjean
> > >
> > > ...........]<(({?<...............<?}))><...............................
> > >  ) ) ) ) )       __                      __
> > > ( ( ( ( (       |__)                    |  _
> > >  ) ) ) ) )      |   hilippe             |__)rosjean
> > > ( ( ( ( (       Marine Biol. Lab., ULB, Belgium
> > >  ) ) ) ) )                               __
> > > ( ( ( ( (       |\  /|                  |__)
> > >  ) ) ) ) )      | \/ |ariculture &      |__)iostatistics
> > > ( ( ( ( (
> > >  ) ) ) ) )      e-mail: phgrosje at ulb.ac.be or phgrosjean at sciviews.org
> > > ( ( ( ( (       SciViews project coordinator (http://www.sciviews.org)
> > >  ) ) ) ) )      tel: 00-32-2-650.29.70 (lab), 00-32-2-673.31.33 (home)
> > > ( ( ( ( (
> > >  ) ) ) ) )      "I'm 100% confident that p is between 0 and 1"
> > > ( ( ( ( (                                  L. Gonick & W. Smith (1993)
> > >  ) ) ) ) )
> > > .......................................................................
> > >
> > > -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
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> >
> > --
> > Laurent Gautier                 CBS, Building 208, DTU
> > PhD. Student                    D-2800 Lyngby,Denmark
> > tel: +45 45 25 24 85            http://www.cbs.dtu.dk/laurent
> > -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
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> > Send "info", "help", or "[un]subscribe"
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> 
> --
> Frank E Harrell Jr              Prof. of Biostatistics & Statistics
> Div. of Biostatistics & Epidem. Dept. of Health Evaluation Sciences
> U. Virginia School of Medicine  http://hesweb1.med.virginia.edu/biostat
> -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
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