Use TRUE. On Sun, Mar 9, 2008 at 5:05 AM, Laurent Gautier <[EMAIL PROTECTED]> wrote: > Dear list, > > I am having a question regarding the extract function "[". > > The man page says that one usage with k-dimensional arrays is to > specify k indices to "[", with an empty index indicating that all > entries in that dimension are selected. > > The question is the following: is there an R object qualifying as an > "empty index" ? I understand that the lazy evaluation of parameters > allows one to > have genuinely missing parameters, but I would like to have an object > instead. I understand that one can always have an if/else workaround, > but I thought should ask, just in case. > > I tried with NULL but with little success, as it appears to give the > same results > as an empty vector. > > m = matrix(1, 2, 2) > > m[1, NULL] > numeric(0) > > m[1, integer(0)] > numeric(0) > > Since I was at it, I noted that the result obtained with "numeric(0)" > definitely makes sense but could as well be seen as challenging the > concept of an empty index presented in the man page (One could somehow > expect the presence of an object meaning "everything" rather than > "missingness" meaning it). > > > Thanks, > > > Laurent > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel >
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