R help - Jul 2008 - update search path for attached data

Dear list,

is there a way of updating the search path when using attach() for a data set.

I am overwriting a variable in a data frame. To update teh search path I do
the follwoing:
> attach(dataset)
> some data manipulation of dataset
> detach(dataset)
> attach(dataset) # to update the search path
Is there a way to avoid the numerous detach() and attach() commands?

Thanks in advance,
Ulrich Leopold

On Fri, 4 Jul 2008, Ulrich Leopold wrote:
> Dear list,
>
> is there a way of updating the search path when using attach() for a data
set.
>
> I am overwriting a variable in a data frame. To update teh search path I do
> the follwoing:
>
>> attach(dataset)
>> some data manipulation of dataset
>> detach(dataset)
>> attach(dataset) # to update the search path
>
> Is there a way to avoid the numerous detach() and attach() commands?
Not if 'dataset' is that data frame (you didn't actually say).  From
the
help page:

      The database is not actually attached.  Rather, a new environment
      is created on the search path and the elements of a list
      (including columns of a data frame) or objects in a save file or
      an environment are _copied_ into the new environment.  If you use
      '<<-' or 'assign' to assign to an attached database,
you only
      alter the attached copy, not the original object.

So you can both change the data frame and assign the column to pos=2 to 
get the effect of what you appear to want.
> Thanks in advance,
> Ulrich Leopold


-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
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