Don't know whether it will suffice. Lm() was just an example. Are you going to re-write lm(), e.g. lm.zoo(), to accept lists? I am more thinking of a general purpose class that would pass wherever data.frame is expected.
Probably I need to wait until the new version of zoo comes out. At the very least it could be a good prototype for what I have in mind. Thanks for the info, Vadim > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Gabor > Grothendieck > Sent: Thursday, November 25, 2004 7:42 PM > To: [EMAIL PROTECTED] > Subject: Re: [Rd] Lightweight data frame class > > Vadim Ogranovich <vograno <at> evafunds.com> writes: > > : > : Hi, > : > : As far as I can tell data.frame class adds two features to those of > : lists: > : * matrix structure via [,] and [,]<- operators (well, I > know these are > : actually "["(i, j, ...), not "[,]"). > : * row names attribute. > : > : It seems that the overhead of the support for the row names, both > : computational and RAM-wise, is rather non-trivial. I frequently > : subscript from a data.frame, i.e. use [,] on data frames, > and my timing > : shows that the equivalent list operation is about 7 times > faster, see > : below. > : > : On the other hand, at least in my usage pattern, I really > rarely benefit > : from the row names attribute, so as far as I am concerned > row names is > : just an overhead. (Of course the speed difference may be > due to other > : factors, the only thing I can tell is that subscripting is > very slow in > : data frames relative to in lists). > : > : I thought of writing a new class, say > lightweight.data.frame, that would > : be polymorphic with the existing data.frame class. The class would > : inherit from "list" and implement [,], [,]<- operators. It > would also > : implement the "rownames" function that would return > seq(nrow(x)), etc. > : It should also implement as.data.frame to avoid the overhead of > : conversion to a full-blown data.frame in calls like lm(y ~ x, > : data=myLightweightDataframe). > > The next version of zoo (currently in > test) supports lists in the data argument of lm and can also > merge zoo series into a list (or to another zoo series, as it > does now). > Would that be a sufficient alternative? > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > ______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
