R: R scripts and parameters

Sorry. This is still unclear to me.
I generated a file called "Test.R" that contains the following lines:

commandArgs(TRUE)
cat("\n A = ",A,"\n")
cat("\n B = ",B,"\n")
cat("\n C = ",C,"\n")

First of all I have to clarify which command line we are talking about.
If I run the command "Rscript" from a Windows terminal, the system does not recognize such a command:
C:\Documents and Settings\Monville\Utilities-Dir>Rscript Test.R aa bb cc
"Rscript" non ? riconosciuto come comando interno o esterno,
un programma eseguibile o un file batch.
The above system response tells me that Rscript is not recognized either as an internal or external command, an executable or a batch file.

In fact Rscript is an R command. Nevertheless, I started an R session and tried such a command from R console command line
and got the following:

getwd()

[1] "C:/Documents and Settings/Monville/Utilities-Dir"

Rscript Test.R aa bb cc

Error: unexpected symbol in "Rscript Test.R"

I feel I do not have a good grasp of how to run R scripts the same way as I usually run C programs.
Any help is welcome.
Thank  you.

Maura





-----Messaggio originale-----
Da: Duncan Murdoch [mailto:murdoch at stats.uwo.ca]
Inviato: mar 17/02/2009 17.34
A: mauede at alice.it
Cc: r-help at stat.math.ethz.ch
Oggetto: Re: [R] R scripts and parameters

On 2/17/2009 10:55 AM, mauede at alice.it wrote:

A couple of weeks ago I asked how it is possible to run an R script (not a function) passing some parameters.
Someone suggested the function "commandArgs()".
I read the on-line help and found no clarifying example. Therefore I do not know how to use it appropriately.
I noticed this function returns the pathname of the R executable which is not what I need.

I meant to ask if it is possible to open an R session and launch a script passing parameters that the script can retrieve and use itself.
Just like in C I can run a program and call it with  some arguments

Example_Prog A B C

The program "Example_Prog" can acess its own arguments through the data structures "argc" an "argv".

How can I launch an R script simulating the above mechanism ?
Shall I use source ("script-name") ?
Where are the arguments to be passed, as part of the source call ?
Is the function "commandArgs" to be places as one of the first code lines of the script in order to access its own arguments ?
Is there any "commandArgs" usage example ?

Gabor gave you a solution from within R.  If you want to run a script
from the command line, then use commandArgs(TRUE).  For example, put
this into the file test.R:

commandArgs(TRUE)

(The TRUE says you only want to see the trailing arguments, not
everything else on the command line.)

Then from the command line, do

Rscript test.R A B C

and you'll see the output

[1] "A" "B" "C"

Duncan Murdoch




tutti i telefonini TIM!


	[[alternative HTML version deleted]]