[R] Basic function output/scope question

[Erik Iverson]

Hello, 

> 
> testfunc<-function(x)
> { y<-10
> print(y)
> print(x)
> }
> 
> testfunc(4)
> 
> The variables x and y are accessible during execution of the function
> "testfunc" but not afterwards.  

In R, expressions return values.  When you define a function, ?function says that, "If the end of a function is reached without calling 'return', the value of the last evaluated expression is returned." 

So you are correct, 'x' and 'y' are local variables, and by all accounts they should be.  If you want their values accessible, simply return them.

## return just y
testfunc2 <- function(x) {
   y <- 10
   y
}

## return both x and y 
testfunc2 <- function(x) {
   y <- 10
   list(x, y)
}

There are ways to make x and y global from within a function, but in general that is not the R way to do things! 

Hope that helps, 
Erik Iverson