Forgot to answer this one: > It would seem natural that metadata associated with one dimension: > would a table-like object
Right. A data frame has the problem that for most use cases one would want that each dimension length matches the *rows* of the data frame instead of the columns, but it is the columns what we would have "for free" when allowing "dimmeta" elements to be lists... Enrique -----Original Message----- From: Laurent Gautier [mailto:lgaut...@gmail.com] Sent: jueves, 09 de julio de 2009 14:15 Cc: Heinz Tuechler; Bengoechea Bartolomé Enrique (SIES 73); Tony Plate; Henrik Bengtsson; r-devel@r-project.org Subject: Re: [Rd] Suggestion: Dimension-sensitive attributes Starting by working on an interface for such object(s) is probably the first step toward a unified solution, and this before about if and how R attributes are used. It would also help to ensure a smooth transition from the existing classes implementing a similar solution (first the interface is added to those classes, then after a grace period the classes are eventually refactored). Dimension-level is what seems to the be most needed... but I am not convinced of the practicality of the object-level, and cell-level scheme s proposed: - Object-level, if not linked to any dimension-attribute is such saying that one want to attach anything to any object. That's what attr() is already doing. - Cell-level, is may be out-of-scope for one first trial (but may be I missed the use-cases for it) If starting with behaviour, it seems to boil to having "["/"[<-" and "dimmeta()"/"dimmeta<-()", : - extract "[" / replace "[<-" : * keeps working the way it already does * extracts a subset of the object as well as a subset of the dimension-associated metadata. * departing too much from the way "[" is working and add behind-the-curtain name matching will only compromise the chances of adoption. * forget about the bit about which metadata is kept and which one isn't when using "[". Make a function "unmeta()" (similar behavior to "unname()") to drop them all, or work it out with something like > dimmeta(x, 1) <- NULL # drop the metadata associated with dimension 1 - access the dimension-associated metadata: * may be a function called "dimmeta()" (for consistency with "dimnames()") ? The signature could be dimmeta(x, i), with x the object, and i the dimension requested. A replace function "dimmeta<-"(x, i, value) would be provided. In the abstract the "names" associated with a given dimension is just one of possible metadata, but I'd keep away from meddling with it for a start. It would seem natural that metadata associated with one dimension: would a table-like object (data.frame seems natural in R, and unfortunately there is no data.frame-like structure in R). L. ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
