R help - Dec 2009 - Fwd: Evaluating a function within a pre-defined environment?

Hi all,

I have a somewhat confusing question that I was wondering if someone
could help with. I have a pre-defined environment with some variables,
and I would like to define a function, such that when it is called, it
actually manipulates the variables in that environment, leaving them
to be examined later. I see from the R language definition that

"When a function is called, a new environment (called the evaluation
environment) is created, whose enclosure (see Environment objects) is
the environment from the function closure. This new environment is
initially populated with the unevaluated arguments to the function; as
evaluation proceeds, local variables are created within it."

So basically, I think I am asking if it is possible to pre-create my
own "evaluation environment" and have it retain the state that it was
in at the end of the function call?

Example:

e <- new.env()
e$x <- 3
f <- function(xx) x <- x + xx

can I then call f(2) and have it leave e$x at 5 after the function
returns? I know that

environment(f) <- e

goes part of the way, but I would like to let the function also write
to the environment.

Thanks for any advice.

--David

e <- new.env()
e$x <- 2
f <- function(a, e) { e$x <- e$x + a; e$x }
f(3, e)
e$x # 5

Another way to accomplish this is to use the proto package which puts
the whole thing into an object oriented framework.  See
http://r-proto.googlecode.com

library(proto)
p <- proto(x = 2, f = function(this, a) { this$x <- this$x + a; this$x })
p$f(3) # 5


On Wed, Dec 9, 2009 at 4:54 PM, David Reiss <dreiss at systemsbiology.org>
wrote:
> Hi all,
>
> I have a somewhat confusing question that I was wondering if someone
> could help with. I have a pre-defined environment with some variables,
> and I would like to define a function, such that when it is called, it
> actually manipulates the variables in that environment, leaving them
> to be examined later. I see from the R language definition that
>
> "When a function is called, a new environment (called the evaluation
> environment) is created, whose enclosure (see Environment objects) is
> the environment from the function closure. This new environment is
> initially populated with the unevaluated arguments to the function; as
> evaluation proceeds, local variables are created within it."
>
> So basically, I think I am asking if it is possible to pre-create my
> own "evaluation environment" and have it retain the state that it
was
> in at the end of the function call?
>
> Example:
>
> e <- new.env()
> e$x <- 3
> f <- function(xx) x <- x + xx
>
> can I then call f(2) and have it leave e$x at 5 after the function
> returns? I know that
>
> environment(f) <- e
>
> goes part of the way, but I would like to let the function also write
> to the environment.
>
> Thanks for any advice.
>
> --David
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

Ideally I would like to be able to use the function f (in my example)
as-is, without having to designate the environment as an argument, or
to otherwise have to use "e$x" in the function body.

thanks for any further advice...

On Wed, Dec 9, 2009 at 2:36 PM, Gabor Grothendieck
<ggrothendieck at gmail.com> wrote:
> e <- new.env()
> e$x <- 2
> f <- function(a, e) { e$x <- e$x + a; e$x }
> f(3, e)
> e$x # 5
>
> Another way to accomplish this is to use the proto package which puts
> the whole thing into an object oriented framework. ?See
> http://r-proto.googlecode.com
>
> library(proto)
> p <- proto(x = 2, f = function(this, a) { this$x <- this$x + a;
this$x })
> p$f(3) # 5
>
>
> On Wed, Dec 9, 2009 at 4:54 PM, David Reiss <dreiss at
systemsbiology.org> wrote:
>> Hi all,
>>
>> I have a somewhat confusing question that I was wondering if someone
>> could help with. I have a pre-defined environment with some variables,
>> and I would like to define a function, such that when it is called, it
>> actually manipulates the variables in that environment, leaving them
>> to be examined later. I see from the R language definition that
>>
>> "When a function is called, a new environment (called the
evaluation
>> environment) is created, whose enclosure (see Environment objects) is
>> the environment from the function closure. This new environment is
>> initially populated with the unevaluated arguments to the function; as
>> evaluation proceeds, local variables are created within it."
>>
>> So basically, I think I am asking if it is possible to pre-create my
>> own "evaluation environment" and have it retain the state
that it was
>> in at the end of the function call?
>>
>> Example:
>>
>> e <- new.env()
>> e$x <- 3
>> f <- function(xx) x <- x + xx
>>
>> can I then call f(2) and have it leave e$x at 5 after the function
>> returns? I know that
>>
>> environment(f) <- e
>>
>> goes part of the way, but I would like to let the function also write
>> to the environment.
>>
>> Thanks for any advice.
>>
>> --David
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>

On Wed, 9 Dec 2009, David Reiss wrote:
> Ideally I would like to be able to use the function f (in my example)
> as-is, without having to designate the environment as an argument, or
> to otherwise have to use "e$x" in the function body.
>
> thanks for any further advice...
Perhaps you want something along the lines of the open.account example of

 	R-intro 10.7 Scope

??

Chuck
>
> On Wed, Dec 9, 2009 at 2:36 PM, Gabor Grothendieck
> <ggrothendieck at gmail.com> wrote:
>> e <- new.env()
>> e$x <- 2
>> f <- function(a, e) { e$x <- e$x + a; e$x }
>> f(3, e)
>> e$x # 5
>>
>> Another way to accomplish this is to use the proto package which puts
>> the whole thing into an object oriented framework. ?See
>> http://r-proto.googlecode.com
>>
>> library(proto)
>> p <- proto(x = 2, f = function(this, a) { this$x <- this$x + a;
this$x })
>> p$f(3) # 5
>>
>>
>> On Wed, Dec 9, 2009 at 4:54 PM, David Reiss <dreiss at
systemsbiology.org> wrote:
>>> Hi all,
>>>
>>> I have a somewhat confusing question that I was wondering if
someone
>>> could help with. I have a pre-defined environment with some
variables,
>>> and I would like to define a function, such that when it is called,
it
>>> actually manipulates the variables in that environment, leaving
them
>>> to be examined later. I see from the R language definition that
>>>
>>> "When a function is called, a new environment (called the
evaluation
>>> environment) is created, whose enclosure (see Environment objects)
is
>>> the environment from the function closure. This new environment is
>>> initially populated with the unevaluated arguments to the function;
as
>>> evaluation proceeds, local variables are created within it."
>>>
>>> So basically, I think I am asking if it is possible to pre-create
my
>>> own "evaluation environment" and have it retain the state
that it was
>>> in at the end of the function call?
>>>
>>> Example:
>>>
>>> e <- new.env()
>>> e$x <- 3
>>> f <- function(xx) x <- x + xx
>>>
>>> can I then call f(2) and have it leave e$x at 5 after the function
>>> returns? I know that
>>>
>>> environment(f) <- e
>>>
>>> goes part of the way, but I would like to let the function also
write
>>> to the environment.
>>>
>>> Thanks for any advice.
>>>
>>> --David
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
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