[R] About source()

[Rainer M Krug]

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On 04/01/12 10:39, Uwe Ligges wrote:
> 
> 
> On 03.01.2012 21:22, Li SUN wrote:
>> Thanks, Rolf, Justin and Uwe!
>> 
>> Actually I wanted to run .R file as a script, just like what
>> people do for bash scripts or python scripts. It seems to me that
>> adding "#!/usr/bin/R -f" at the first line is what I need. Is
>> this true?
> 
> 
> Perhaps even "Rscript" rather than "R".

And there is also littler from Dirk Eddelbüttel:

http://dirk.eddelbuettel.com/code/littler.html

- From the description: "littler provides hash-bang (i.e. script
starting with #!/some/path) capability for GNU R, as well as simple
command-line and piping use."

Similar to Rscript, but with some differences.

I used both, and in most cases they are equivalent.


Rainer


> 
> Uwe Ligges
> 
>> Li Sun
>> 
>> 
>> 2012/1/2 Rolf Turner<rolf.turner at xtra.co.nz>:
>>> On 03/01/12 17:02, Li SUN wrote:
>>>> 
>>>> Hello,
>>>> 
>>>> I am a beginner to the R language and find it fantastic and 
>>>> well-designed, quite different from other programming
>>>> languages.
>>> 
>>> What a refreshingly sensible attitude!!! :-)
>>> 
>>>> This is the first time I post on the r-help mailing list.
>>>> 
>>>> In invoking the function source(filename), it seems that the
>>>> filename has to exist in the current working directory,
>>>> otherwise it has to be specified in full path. So is there
>>>> any mechanism(such as environment variable) to specify an
>>>> additional directory of .R files that source() could search
>>>> in?
>>> 
>>> 
>>> I'm no expert on this, and others may correct me, but
>>> 
>>> (1) I don't believe any such mechanism exists.
>>> 
>>> (2) It's probably not a good idea, even if such a mechanism 
>>> were to exist.  Directories have a tree structure, rather than 
>>> being linearly ordered in the way that data bases on your R
>>> search path are ordered.
>>> 
>>> I believe you would run all sorts of risks of confusion and of
>>> getting the wrong file were you to invoke such a mechanism.
>>> 
>>> It is ``good practice'' to have separate directories
>>> associated with different projects and to situate all files,
>>> that you might wish to source in respect of a given project, in
>>> the directory associated with that project.
>>> 
>>> I know that this is an irritating sort of response --- ``No,
>>> you can't do that, and you shouldn't do it anyway!'' --- but I
>>> sincerely believe this to be true.
>>> 
>>> That being said, I also believe that you could program up such
>>> a mechanism yourself. I.e. build a function "source2()" which
>>> would have a "hard coded" list of directories to search, and
>>> would make use of the "try()" function.
>>> 
>>> Might be a good exercise for you, given that you are starting
>>> out in R and looking to upgrade your skills! :-)
>>> 
>>> cheers,
>>> 
>>> Rolf Turner
>>> 
>>> 
>> 
>> ______________________________________________ 
>> R-help at 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 at 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.


- -- 
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation
Biology, UCT), Dipl. Phys. (Germany)

Centre of Excellence for Invasion Biology
Stellenbosch University
South Africa

Tel :       +33 - (0)9 53 10 27 44
Cell:       +33 - (0)6 85 62 59 98
Fax :       +33 - (0)9 58 10 27 44

Fax (D):    +49 - (0)3 21 21 25 22 44

email:      Rainer at krugs.de

Skype:      RMkrug
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