[R] Variable scope in functions - best practices

Berend Hasselman bhh at xs4all.nl
Sun Jul 24 17:24:55 CEST 2011

Noah Silverman wrote:
> Hi,
> I'm working on coding some more complex things in R and have need to break
> much of the logic into functions.
> I have several "global" variables that I want to change with a given
> function.  (The variable has a different value after the function is
> called.)
> In other languages like C, this is simple.  However, in R, if a function
> changes a variable, that change only occurs in the frame of that function. 
> So, when the function returns, the old value is still there. 
> Of course, I could just have the function return the value, but some
> functions change 5-6 variables.  So, I could have a function return a
> list, and then parse that list every time, but that seems like an
> excessive amount of overhead.  (Especially as some functions may be called
> many many times.)

Maybe this helps



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