On Fri, 10 Jun 2005, Martyn Plummer wrote: > The library() function prints an information message when objects are > masked on the search path by (or from) a newly attached package. The > attach() function, however, doesn't. Is there a good reason for this? > I have adapted the machinery for checking conflicts used in the library > () function to attach(). If there are no objections, I will check this > into R-devel. > > I have seen new users get into terrible trouble with attach, e.g. > 1) attaching the same database multiple times, or > 2) Masking a vector in an attached data frame with a transformed version > in the global environment and *then* re-running a script that transforms > the transformed variable. For example, run this snippet twice and you > might get a surprise. > > foo <- data.frame(x=1:10) > attach(foo) > x <- x/2 > > A warning would certainly help. > > Incidentally, (1) occurs in the example for the beavers data set. I > didn't find any other problems.
Not so: it attaches different dfs with the same column names. I think that is quite common and normally intentional. (Not cleaning up is not good practice though, and that example can be improved a lot.) ______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
