[R] How to comment out multiple lines in R source code?

Emmanuel Paradis paradis at isem.univ-montp2.fr
Thu Oct 11 15:22:46 CEST 2001

At 07:33 11/10/01 +0100, Prof Brian D Ripley <ripley at stats.ox.ac.uk> wrote:
>On Wed, 10 Oct 2001, [iso-8859-1] Göran Broström wrote:
>> On 10 Oct 2001 rossini at blindglobe.net wrote:
>> > >>>>> "jl" == jonathan li <jonathan_li at agilent.com> writes:
>> >
>> >     jl> Hi, Is there a way to comment out multiple lines at once in R
>> >     jl> source code like C language's /* */ struct? This is quite
>> >     jl> useful when one is testing different sections of a source
>> >     jl> code.
>> >
>> > One alternative is to use editor macros for this.
>> >
>> > (X)Emacs, when using ESS, supports comment-region and uncomment-region
>> > commands.
>> >
>> > best,
>> > -tony
>> You may also try
>> if (FALSE){
>> ...
>> ...
>> }
>Yes, you will see that in e.g. the MASS scripts to comment out S code that
>does not (yet) work in R.
>One warning: in that method the `commented' code has to syntactically
>valid, and that has caught me more than once.   So I usually use ESS's

In (X)Emacs, you can add a character at the beginning of several lines at
once by selecting a block of lines, and then typing C-x r t # (where you
can replace # by any other character or even a string; `C-x' means
`Ctrl-x'). This does not need ESS. You can even add the # in the middle of
the lines if your block selection starts at this point (in case you want to
comment out the right hand-side of a command... maybe not very usual).

BTW, the possibility to (un)comment out a block a R commands does not
appear in the ESS menu (it does in C-mode), and I did not find it in ESS's
doc (but I admit I did not read it all carefully).

Emmanuel Paradis

Emmanuel Paradis
Laboratoire de Paléontologie
Institut des Sciences de l'Évolution
Université Montpellier II
F-34095 Montpellier cédex 05
   phone: +33  4 67 14 39 64
     fax: +33  4 67 14 36 10
  mailto:paradis at isem.univ-montp2.fr
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