Vadim Ogranovich <vograno <at> evafunds.com> writes: : : 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?
A previous unreleased version of zoo did hack lm but the current test version interfaces to lm without making any changes to lm at all. : I am more thinking of a general purpose class that would pass wherever : data.frame is expected. Yes, I figured so. The lightweight data frame idea seems neat but thought I would mention this, in addition, in case its germane. : : 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. If you want it before then contact me offlist and I can send you the beta test version. : : Thanks for the info, : Vadim : : > -----Original Message----- : > From: r-devel-bounces <at> stat.math.ethz.ch : > [mailto:r-devel-bounces <at> stat.math.ethz.ch] On Behalf Of Gabor : > Grothendieck : > Sent: Thursday, November 25, 2004 7:42 PM : > To: r-devel <at> stat.math.ethz.ch : > 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? : > : > ______________________________________________ : > R-devel <at> stat.math.ethz.ch mailing list : > https://stat.ethz.ch/mailman/listinfo/r-devel : > : : ______________________________________________ : R-devel <at> stat.math.ethz.ch mailing list : https://stat.ethz.ch/mailman/listinfo/r-devel : : ______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
