Tony Plate wrote: > > At Monday 07:31 PM 3/24/2003 +0100, Uwe Ligges wrote: > >Tony Plate wrote: > >>As wolski/Eryk's example shows, it seems that "[[" for lists accepts > >>abbreviations, whereas "[" does not. Is this intended? (This is a difference > >>from S-plus - both "[" and "[[" for lists accept abbreviations in S-plus (V6.1 for > >>Windows at least.) > > > >The general subscripting operator [] doesn't support abbreviations at all. I don't > >know of any reference that states [] supports partial matching of character strings. > > My copy of the Blue Book, Section 11.4.1 (p357 of 1996 printing) seems to pretty > strongly imply that "[" supports partial matching of character strings (it gives > S-code for handling of indices, and uses pmatch for handling character indices in > extraction contexts). However, I certainly wouldn't advocate adding this to R if > all existing software works without this capability. It does seem worth documenting > in place where beginning users can find it though. > > >>The name returned by "[" for a non-existent element of a list also seems of > >>dubious correctness. > >> > >>>list(abc=123)[["a"]] > >>[1] 123 > >> > >>>list(abc=123)["a"] > >>$"NA" > >>NULL > > > >Everything as expected from my point of view. Do you mean the "NA" is "dubious"? > > Yes, the string "NA" as a name is of dubious correctness. The behavior of "[" with > vectors is more what I would have expected: > > c(abc=123)["ab"] > <NA> > NA > > > > -- Tony Plate
Two last points: - related to Tony Plate's mail: I don't have any S books at home (where I am right now). - related to Spencer Graves' mail: Transportability is not really an issue. Or do you want to write code relying on partial matching? I won't-or try to avoid it, at least. Example: LL <- list(a1=1, a2=2) LL$a # Hmmm ... partial matching can be quite dangerous! I leave this topic open now. Uwe ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
