[R] Dummy quesion about environment

[Peter Dalgaard]

"Ron Ophir" <ron.ophir at weizmann.ac.il> writes:

> Hi,
> I'm trying to understand environment object in R.
> I used the example:
>   f <- function(x) {
>          y <- 10
>          g <- function(x) x + y
>          return(g)
>      }
>      h <- f()
>      h(3)
> then i saw that f return an environment
> > h
> function(x) x + y
> <environment: 01B28570>
> but I coudn't access to x and y object in that environment:
> I tried 
> get("x",env=h)
> I tried
> h$y
> can I access y and x?

Well, there are special issues with x above, but the basic thing is to
take environment(h). Notice that h _is_ a function that _has_ an
associated environment. 

> get("y",env=environment(h))
[1] 10

As I said, x is stranger, which is because you used f() in the call:

> get("x",env=environment(h))

> str(get("x",env=environment(h)))
 symbol
> a <- get("x",env=environment(h))
> missing(a)
[1] TRUE
> evalq(x,environment(h))
Error in eval(expr, envir, enclos) : argument "x" is missing, with no
 default
> evalq(missing(x),environment(h))
[1] TRUE

You'll get the point if you look long and hard enough...

> how can I see an environment tree? 

You can't. You can see the parent of an environment, the grandparent,
etc., but there is no way to see which children a given environment
has. 

> oes search does it?

Huh?

> Thanks,
> Ron
> 
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-- 
   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
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