[R] Odp: Problem with retrieving updated variables after attach()

Wacek Kusnierczyk Waclaw.Marcin.Kusnierczyk at idi.ntnu.no
Tue Feb 10 14:23:37 CET 2009


Berwin A Turlach wrote:
> G'day David,
>
> On Tue, 10 Feb 2009 13:23:50 +0100
> David Croll <david.croll at gmx.ch> wrote:
>
>   
>> Well, I knew that attach() only creates a copy of the variables in
>> the search path.
>>
>> What I wanted to ask was how to *retrieve* that copy...
>>
>>  > mat
>>  id age
>> 1 NA  NA
>> 2 NA  NA
>> 3 NA  NA
>> 4 NA  NA
>> 5 NA  NA  
>>
>>  > attach(mat)
>>
>>  > id <<- sample(100,5)
>>  > age <<- rnorm(5,mean=30)
>>
>> How can I make a new data frame out of the id and age that were
>> changed above?
>>     
>
> R> new.df <- data.frame(id,age)
>
> Or, perhaps more automatic:
>
> R> new.df <- do.call(data.frame, sapply(ls(pos=2), as.name))
>
>   

or perhaps:

new.df <- as.data.frame(mget(names(mat), as.environment(2)))

vQ



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