On Fri, 2008-07-04 at 15:13 +0100, Prof Brian Ripley wrote: > 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.
How can I update directly the search path without using detach() attach() or '<<-' assign()? Maybe using attach() or assign methods is not so convenient anyway in my case as it creates always a copy of each data set? Is there a good practise in programming in R by using search paths but keep memory as well as updating of the search path to a minimum? Ulrich -- ______________________________________________________________________ Ulrich Leopold Resource Centre for Environmental Technologies, Public Research Centre Henri Tudor, Technoport Schlassgoart, 66 rue de Luxembourg, P.O. BOX 144, L-4002 Esch-sur-Alzette, Luxembourg tel: +352 425991 618 fax: +352 425991 601 mobile: +352 691 304813 http://www.crte.lu Computational Bio- and Physical Geography, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Nieuwe Achtergracht 166, NL-1018WV Amsterdam, The Netherlands http://www.science.uva.nl/ibed ______________________________________________ R-help@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.