[R] selectively importing functions etc. from files

Charles C. Berry cberry at tajo.ucsd.edu
Sun Nov 30 19:38:40 CET 2008

On Sat, 29 Nov 2008, Faheem Mitha wrote:

> Hi,
> If I want to import the contents of a R file into another one, I can do
> source("foo.R")
> However, this imports everything from foo.R, including all functions and 
> global variables. Is there a way of selectively importing individual 
> functions etc., in a similar fashion to Python's
> from foo import bar

There are probably a lot of ways to skin this cat.

But you might want to explain why you want to do this in the first place.

It may turn out that the problem you wish to solve is better addressed by 
placing your objects in a package that is attached far down the search 

A simple way to do what you say you want:


 	source("foo.R", local=TRUE)

from within a function. Then either assign( ..., envir=.GlobalEnv ) 
selected objects or attach( list( ) ) them.

Another way is to use parse, as.character.srcref, and friends to avoid 
evaluating each of the objects, then eval() selected expressions in the 
desired environment.


> ? Thanks in advance. Please cc me on any reply.
>                                                         Regards, Faheem.
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Charles C. Berry                            (858) 534-2098
                                             Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu	            UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/  La Jolla, San Diego 92093-0901

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