R help - Aug 2011 - How to modify the dot-dot-dot argument using level names instead of position

Dear R-users,

In the R internals manual, it is said that one can extract the
elements of the dot-dot-dot argument using the special symbols ..1 or
..2. It seems to work just fine but I was wondering if there is a way
one can extract or modify the content of the dot-dot-dot argument
using a level name instead of its position?

For instance, assuming that list(...) returns:
$a
 [1]  1  2  3  4  5  6  7  8  9 10

$b
[1] "a" "b" "c" "d" "e"
"f" "g" "h"

is there a way to modify level b without knowing that it is the second level?

Thank you

Sebastien

Hi,

I thought "..2 <- 1" was a correct way to modify the content of the
2nd level of dot-dot-dot because it did not return any error message.
However, this appears to have no effect whatsoever on the content of
dot-dot-dot. So, I guess I should modify my question to: is it
possible to modify the content of dot-dot-dot by any means?

Thank

On Wed, Aug 31, 2011 at 9:25 AM, S?bastien Bihorel <pomchip at free.fr>
wrote:
> Dear R-users,
>
> In the R internals manual, it is said that one can extract the
> elements of the dot-dot-dot argument using the special symbols ..1 or
> ..2. It seems to work just fine but I was wondering if there is a way
> one can extract or modify the content of the dot-dot-dot argument
> using a level name instead of its position?
>
> For instance, assuming that list(...) returns:
> $a
> ?[1] 1 2 3 4 5 6 7 8 9 10
>
> $b
> [1] "a" "b" "c" "d" "e"
"f" "g" "h"
>
> is there a way to modify level b without knowing that it is the second
level?
>
> Thank you
>
> Sebastien
>

On 31/08/2011 9:41 AM, S?bastien Bihorel wrote:
> Hi,
>
> I thought "..2<- 1" was a correct way to modify the content of
the
> 2nd level of dot-dot-dot because it did not return any error message.
> However, this appears to have no effect whatsoever on the content of
> dot-dot-dot. So, I guess I should modify my question to: is it
> possible to modify the content of dot-dot-dot by any means?
Not from R code.  You can achieve the same effect by converting it to a 
list, manipulating the list, and then using do.call() to pass it on.

Duncan Murdoch
> Thank
>
> On Wed, Aug 31, 2011 at 9:25 AM, S?bastien Bihorel<pomchip at
free.fr>  wrote:
> >  Dear R-users,
> >
> >  In the R internals manual, it is said that one can extract the
> >  elements of the dot-dot-dot argument using the special symbols ..1 or
> >  ..2. It seems to work just fine but I was wondering if there is a way
> >  one can extract or modify the content of the dot-dot-dot argument
> >  using a level name instead of its position?
> >
> >  For instance, assuming that list(...) returns:
> >  $a
> >    [1] 1 2 3 4 5 6 7 8 9 10
> >
> >  $b
> >  [1] "a" "b" "c" "d"
"e" "f" "g" "h"
> >
> >  is there a way to modify level b without knowing that it is the
second level?
> >
> >  Thank you
> >
> >  Sebastien
> >
>
> ______________________________________________
> 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.

Thanks Duncan

On Wed, Aug 31, 2011 at 9:43 AM, Duncan Murdoch
<murdoch.duncan at gmail.com> wrote:
> On 31/08/2011 9:41 AM, S?bastien Bihorel wrote:
>>
>> Hi,
>>
>> I thought "..2<- 1" was a correct way to modify the
content of the
>> 2nd level of dot-dot-dot because it did not return any error message.
>> However, this appears to have no effect whatsoever on the content of
>> dot-dot-dot. So, I guess I should modify my question to: is it
>> possible to modify the content of dot-dot-dot by any means?
>
> Not from R code. ?You can achieve the same effect by converting it to a
> list, manipulating the list, and then using do.call() to pass it on.
>
> Duncan Murdoch
>
>> Thank
>>
>> On Wed, Aug 31, 2011 at 9:25 AM, S?bastien Bihorel<pomchip at
free.fr>
>> ?wrote:
>> > ?Dear R-users,
>> >
>> > ?In the R internals manual, it is said that one can extract the
>> > ?elements of the dot-dot-dot argument using the special symbols
..1 or
>> > ?..2. It seems to work just fine but I was wondering if there is a
way
>> > ?one can extract or modify the content of the dot-dot-dot argument
>> > ?using a level name instead of its position?
>> >
>> > ?For instance, assuming that list(...) returns:
>> > ?$a
>> > ? ?[1] 1 2 3 4 5 6 7 8 9 10
>> >
>> > ?$b
>> > ?[1] "a" "b" "c" "d"
"e" "f" "g" "h"
>> >
>> > ?is there a way to modify level b without knowing that it is the
second
>> > level?
>> >
>> > ?Thank you
>> >
>> > ?Sebastien
>> >
>>
>> ______________________________________________
>> 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.
>
>