On 2/17/2009 10:55 AM, mau...@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
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