[R] with vs. attach

[Bert Gunter]

... and it's exactly with.default's code !

Cheers,
Bert


Bert Gunter

"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )


On Thu, May 5, 2016 at 7:38 PM, Spencer Graves
<spencer.graves at effectivedefense.org> wrote:
> Hi, David:  That works.  Thanks very much.  Spencer Graves
>
>
>
> On 5/5/2016 7:43 PM, David Winsemius wrote:
>>>
>>> On May 5, 2016, at 5:12 PM, Spencer Graves
>>> <spencer.graves at effectivedefense.org> wrote:
>>>
>>> I want a function to evaluate one argument
>>> in the environment of a data.frame supplied
>>> as another argument.  "attach" works for
>>> this, but "with" does not.  Is there a way
>>> to make "with" work?  I'd rather not attach
>>> the data.frame.
>>>
>>>
>>> With the following two functions "eval.w.attach"
>>> works but "eval.w.with" fails:
>>>
>>>
>>> dat <- data.frame(a=1:2)
>>> eval.w.attach <- function(x, dat){
>>>    attach(dat)
>>>    X <- x
>>>    detach()
>>>    X
>>> }
>>>
>>> eval.w.with <- function(x, dat){
>>>    with(dat, x)
>>> }
>>>
>>> eval.w.attach(a/2, dat) # returns c(.5, 1)
>>
>> How about using eval( substitute( ...))?
>>
>>   eval.w.sub <- function(expr, datt){
>>     eval( substitute(expr), env=datt)
>>                           }
>>   eval.w.sub(a/2, dat)
>> #[1] 0.5 1.0
>>
>>
>
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