[R] R function calling: efficiency of different alternatives

[Ramon Diaz]

Dear all,

I have a piece of code, call it "FA", that will be called thousands of times 
in a typical run of function "FB". I can:

a) define FA as a function outside of FB (in the global environment), and call 
it;
b) define FA as a function inside the body of FB and call it;
c) "expand inline" FA inside FB.

FA mainly does data frame subsetting, runs svd's, and calls compiled C++ code.

I think I recall reading something about differences in efficiency between 
those three approaches, but I can't find the information (I've searched the 
email archives, Venables & Ripley's "S programming" and MASS, the R manuals, 
and Burn's "S Poetry"). 

Are there any real performance differences? 

(I'd personally prefer b) since these functions will hopefully become a 
contributed package, and FA is not supposed to be used directly by an end 
user. I am aware of scoping differences between the three approaches, but 
that is not my main concern now).

Thanks,

Ramón

-- 
Ramón Díaz-Uriarte
Bioinformatics Unit
Centro Nacional de Investigaciones Oncológicas (CNIO)
(Spanish National Cancer Center)
Melchor Fernández Almagro, 3
28029 Madrid (Spain)
http://bioinfo.cnio.es/~rdiaz