[R] Evaluating content of command line arguments

JiHO jo.lists at gmail.com
Fri May 1 04:10:31 CEST 2009

Hello everyone,

I am writing an R script which will be provided with command line  
arguments by a shell script. I read them with commandArgs() but I have  
an issue to make that fool proof.

For example, with test.R containing:


I get:

         $ Rscript test_commandLineArgs.R 3 4 5
         [1] "3" "4" "5"

Now, to make the input more flexible and robust, I want to pass  
*named* arguments, so that the R script does not depend on the order  
of arguments passed and can check which are present/absent etc. I.e.

         $ Rscript test_commandLineArgs.R foo=3 bar=4 5
         [1] "foo=3" "bar=4"

But I am stuck on how to actually execute the code within those  
strings so as to get two variables foo and bar equal to 3 and 4  
respectively. I looked at eval, deparse, substitute and all that but  
did not find anything. Is that possible?

Otherwise I will resort to parsing the arguments with strsplit but I  
would much prefer and more elegant solution.

Thank you very much in advance. Sincerely,


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