Re: [R] exists() and functions

From: Jonathan Greenberg <greenberg_at_ucdavis.edu>
Date: Fri, 25 Jun 2010 13:12:01 -0700

Always nice to answer my own question 3 minutes later. The missing() function does what I want. Still, why DOES this exists() statement fail? Do functions "auto create" the variables once they are called, regardless of whether or not they are assigned?

--j

On Fri, Jun 25, 2010 at 1:05 PM, Jonathan Greenberg <greenberg_at_ucdavis.edu> wrote:
> I'm a bit confused about how exists() work within a function -- I want
> to test for unassigned variables, but I'm doing tests in the main
> environment to figure out the function, so the variables DO exist in
> the parent environment of a function call.
>
> Why does:
> myfunction <- function(variable_outside_function)
> {
>        print(exists("variable_outside_function",inherit=FALSE))
>        print(exists("another_variable_outside_function",inherit=FALSE))
> }
>
> myfunction()
>
> Return:
> [1] TRUE
> [1] FALSE
>
> I didn't assign anything to variable_outside_function, so I'm unclear
> why it thinks it exists...
>
> --j
>



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