OK, I see. Thanks. -Dan On Tue, Jul 13, 2010 at 9:11 AM, John Chambers <j...@r-project.org> wrote:
> > On 7/13/10 8:43 AM, Daniel Murphy wrote: > >> Thank you. For "getDataPart" I was following (my interpretation of) >> advice from the documentation for "Classes": The functions |getDataPart >> <http://127.0.0.1:15455/library/methods/help/getDataPart>| and >> |setDataPart <http://127.0.0.1:15455/library/methods/help/setDataPart>| >> >> are a cleaner, but essentially equivalent way to deal with the data part. >> I interpreted "cleaner" to mean "preferred." From your reply, John, it >> sounds like I should go back to the obj...@.data construct. >> > > No, that's not the distinction. Preferred for what, is the question. In > order for a class to extend a basic type, it has to have that type. Then the > .Data "slot" is a sort of fiction needed for the metadata. > (Because of some "features" of R implementation, it's not quite that > simple. Matrices act like a basic type, and some types, such as > "environment" require a second kludge.) > > > If you really want that slot, the advice holds, but only because there is > no actual ".Data" slot (i.e., attribute). > > But you weren't talking about that at all. In fact (just to contradict my > previous mail) you probably wanted to turn your object into a data.frame. > If so, best to say so: > > > as(z, "data.frame") > > Object of class "data.frame" > x > 1 1 > 2 2 > 3 3 > > and, for that matter: > > > as(z, "list") > [[1]] > [1] 1 2 3 > > -Dan >> On Tue, Jul 13, 2010 at 5:57 AM, John Chambers <j...@r-project.org >> <mailto:j...@r-project.org>> wrote: >> >> On 7/11/10 9:08 PM, Daniel Murphy wrote: >> >> R-Devel: >> >> When I get the data part of an S4 class that >> contains="data.frame", it gives >> me a list, even when the "data.frame" is the S4 version: >> >> d<-data.frame(x=1:3) >> isS4(d) >> >> [1] FALSE # of course >> >> dS4<-new("data.frame",d) >> isS4(dS4) >> >> [1] TRUE # ok >> >> class(dS4) >> >> [1] "data.frame" # good >> attr(,"package") >> [1] "methods" >> >> setClass("A", representation(label="character"), >> contains="data.frame") >> >> [1] "A" >> >> a<-new("A",dS4, label="myFrame") >> getDataPart(a) >> >> [[1]] # oh? >> [1] 1 2 3 >> >> class(a...@.data) >> >> [1] "list" # hmm >> >> names(a) >> >> [1] "x" # sure, that makes sense >> >> a >> >> Object of class "A" >> x >> 1 1 >> 2 2 >> 3 3 >> Slot "label": >> [1] "myFrame" >> >> >> Was I wrong to have expected the "data part" of 'a' to be a >> "data.frame"? >> >> >> Yes. Also, there is a clue in the documentation for getDataPart: >> "rarely suitable to be called directly" >> The data part, aka "data slot", generally does not have a class (S4 >> or S3). >> >> You are probably looking for S3Part(): >> >> > setClass("myFrame", contains = "data.frame") >> [1] "myFrame" >> > z = new("myFrame", data.frame(x=1:3)) >> > z >> Object of class "myFrame" >> >> x >> 1 1 >> 2 2 >> 3 3 >> > S3Part(z) >> Object of class "data.frame" >> >> x >> 1 1 >> 2 2 >> 3 3 >> > S3Part(z, strictS3 = TRUE) >> >> x >> 1 1 >> 2 2 >> 3 3 >> >> >> >> >> Thanks. >> >> Dan Murphy >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-devel@r-project.org <mailto:R-devel@r-project.org> mailing list >> >> https://stat.ethz.ch/mailman/listinfo/r-devel >> >> >> [[alternative HTML version deleted]] ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
