attach provides a copy of rather than aliases to the variables within a
data frame.
d = data.frame(x=0)
attach(d)
x
# 0, from the attached copy of d
x = 1
x
# 1, from the global anvironment
d$x
# 0, from d
x <<- 2
x
# 1, from the global environment
d$x
# 0, from d
get('x', pos=2)
# 2, from the attached copy of d
rm(x)
x
# 2, from the attached copy of d
vQ
David Croll wrote:
> Hello,
>
> suppose I have a data frame:
>
>
>> mat
>>
> id age
> 1 NA NA
> 2 NA NA
> 3 NA NA
> 4 NA NA
> 5 NA NA
>
> Then I attach the data frame:
>
>
>> attach(mat)
>>
>
> I assign some new values...
>
>
>> id <<- sample(100,5)
>> age <<- rnorm(5,mean=30)
>>
>
> Then I want to create a new data frame from the variables id and age which
> still are attached to position 2 of the R environment...
>
>
>> new_mat <- data.frame(ls(pos=2)) # I want to rescue ALL variables that were
>> created by attach(mat)
>>
>
>
>> new_mat
>>
> ls.pos...2.
> 1 age
> 2 id
>
> But this leads to a bogus object... how can I rescue the updated id and age
> values into new_mat?
>
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