On 10/19/05, Marc Schwartz <[EMAIL PROTECTED]> wrote: > On Thu, 2005-10-20 at 01:13 +0100, Ted Harding wrote: > > On 19-Oct-05 Gabor Grothendieck wrote: > > > In the following the first element of xx should have > > > been set to 0 but remains NA. Any comments? > > > > > >> xx <- c(NA,1) > > >> is.na(xx) <- 0 > > >> xx > > > [1] NA 1 > > >> R.version.string # Windows XP > > > [1] "R version 2.2.0, 2005-09-20" > > > > I wonder, has it ever worked? I get the same as you on > > > > R.version.string #Linux > > [1] "R version 1.6.2, 2003-01-10" > > > > R.version.string #Linux > > [1] "R version 1.8.0, 2003-10-08" > > > > R.version.string #Linux > > [1] "R version 2.1.0, 2005-04-08" > > > > with the exception of > > > > R.version.string #Linux > > [1] "R version 1.2.3, 2001-04-26" > > > > which does know about is.na()<- at all. > > > > > > Hmmm > > Ted. > > According to the documentation in ?is.na: > > The generic function is.na<- sets elements to NA. > > and in the details section: > > Function is.na<- may provide a safer way to set missingness. It behaves > differently for factors, for example. > > > In reviewing the Green Book on the top of page 143, it shows an example > in which the RHS of the assignment are the indices into the LHS object > which are to be set to NA. For example: > > > xx <- c(0:5) > > > xx > [1] 0 1 2 3 4 5 > > > is.na(xx) <- c(3, 4) > > > xx > [1] 0 1 NA NA 4 5 > > > Thus, back to Gabor's example, the proper approach would of course be: > > > xx <- c(NA,1) > > > xx > [1] NA 1 > > > xx[is.na(xx)] <- 0 > > > xx > [1] 0 1 > > > HTH, > > Marc Schwartz > > >
Thanks. I actually had read ?is.na but obviously not closely enough. ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
