That's not the problem. The problem is that if you have
ft <- ftable(UCBAdmissions, row.vars = 3:2) ft ## Admit Admitted Rejected ## Dept Gender ## A Male 512 313 ## Female 89 19 ## B Male 353 207 ## Female 17 8 ## C Male 120 205 ## ... etc ... then as.data.frame(ft) gives a deconstructed 24x4 data.frame like this: as.data.frame(ft) ## Dept Gender Admit Freq ## 1 A Male Admitted 512 ## 2 B Male Admitted 353 ## 3 C Male Admitted 120 ## 4 D Male Admitted 138 ## ... etc ... which is fine but it does not address the problem here. The problem here is that we want a a usable data.frame having columns that correspond to ft. We want this 12x4 data.frame: ## Dept Gender Admitted Rejected ## 1 A Male 512 313 ## 2 A Female 89 19 ## 3 B Male 353 207 ## 4 B Female 17 8 ## ... etc ... The links I provided already pointed to the code below which someone posted on SO and solves the problem but I would have thought this would be easy to do in base R and natural to provide. ftable2df <- function(mydata) { ifelse(class(mydata) == "ftable", mydata <- mydata, mydata <- ftable(mydata)) dfrows <- rev(expand.grid(rev(attr(mydata, "row.vars")))) dfcols <- as.data.frame.matrix(mydata) names(dfcols) <- do.call( paste, c(rev(expand.grid(rev(attr(mydata, "col.vars")))), sep = "_")) cbind(dfrows, dfcols) } ftable2df(ft) ## Dept Gender Admitted Rejected ## 1 A Male 512 313 ## 2 A Female 89 19 ## 3 B Male 353 207 ## 4 B Female 17 8 ## ... etc ... Fri, May 15, 2020 at 12:25 PM Martin Maechler <maech...@stat.math.ethz.ch> wrote: > > >>>>> Gabor Grothendieck > >>>>> on Thu, 14 May 2020 06:56:06 -0400 writes: > > > If you are looking at ftable could you also consider adding > > a way to convert an ftable into a usable data.frame such as > > the ftable2df function defined here: > > > https://stackoverflow.com/questions/11141406/reshaping-an-array-to-data-frame/11143126#11143126 > > > and there is an example of using it here: > > > https://stackoverflow.com/questions/61333663/manipulating-an-array-into-a-data-frame-in-base-r/61334756#61334756 > > > Being able to move back and forth between various base class representations > > seems like something that would be natural to provide. > > Sure! > > But there is already an as.data.frame() method for "ftable", > {and I would not want the if(! .. ftable) ftable(x) part anyway. > > What I think many useRs / programmeRs very often forget about > is more-than-2-dimensional arrays {which *are* at the beginning > of that SO question} and that these are often by far the most > efficient data structure (rather than the corresponding data frames). > > and even less people forget that a "table" in base R is just a > special case of a 1-D, 2-D, 3-D, .... array. > (Semantically a special case: "array" with non-negative integer content > > I'd claim that everything you here ("move back and forth between > ...") is already there in the "ftable" implementation in stats, > notably in the source file src/library/stats/R/ftable.R > -> https://svn.r-project.org/R/trunk/src/library/stats/R/ftable.R > > The problem may be in > > 1) too sparse documentation about the close relations > "ftable" <-> "array" <-> "table" <-> "data.frame" > > 2) people not thinking often enough about more-than-2D-arrays and the > special corresponding class "table" in R. > > To start with one: > > > str(UCBAdmissions) > 'table' num [1:2, 1:2, 1:6] 512 313 89 19 353 207 17 8 120 205 ... > - attr(*, "dimnames")=List of 3 > ..$ Admit : chr [1:2] "Admitted" "Rejected" > ..$ Gender: chr [1:2] "Male" "Female" > ..$ Dept : chr [1:6] "A" "B" "C" "D" ... > > > > and look at the *examples* in the help files and the S3 methods > > methods(class = "ftable") > [1] as.data.frame as.matrix as.table format head > print > [7] tail > see '?methods' for accessing help and source code > > methods(class = "table") > [1] [ aperm as.data.frame Axis coerce > initialize > [7] lines plot points print show > slotsFromS3 > [13] summary tail > see '?methods' for accessing help and source code > > > > ... need to close now, there's more to be said ... > > > > > On Thu, May 14, 2020 at 5:32 AM Martin Maechler > > <maech...@stat.math.ethz.ch> wrote: > >> > >> >>>>> SOEIRO Thomas > >> >>>>> on Wed, 13 May 2020 20:27:15 +0000 writes: > >> > >> > Dear all, > >> > I haven't received any feedback so far on my proposal to make > "justify" argument available in stats:::format.ftable > >> > >> > Is this list the appropriate place for this kind of proposal? > >> > >> Yes, it is.. Actually such a post is even a "role model" post > >> for R-devel. > >> > >> > I hope this follow-up to my message won't be taken as rude. Of > course it's not meant to be, but I'm not used to the R mailing lists... > >> > >> well, there could be said much, and many stories told here ... ;-) > >> > >> > Thank you in advance for your comments, > >> > >> > Best, > >> > Thomas > >> > >> The main reasons for "no reaction" (for such nice post) probably > >> are combination of the following > >> > >> - we are busy > >> - if we have time, we think other things are more exciting > >> - we have not used ftable much/at all and are not interested. > >> > >> Even though the first 2 apply to me, I'll have a 2nd look into > >> your post now, and may end up well agreeing with your proposal. > >> > >> Martin Maechler > >> ETH Zurich and R Core team > >> > >> > >> > >> > >> >> Dear all, > >> >> > >> >> justify argument is hard coded in format.ftable: > >> >> > >> >> cbind(apply(LABS, 2L, format, justify = "left"), > >> >> apply(DATA, 2L, format, justify = "right")) > >> >> > >> >> It would be useful to have the possibility to modify the argument > between c("left", "right", "centre", "none") as in format.default. > >> >> > >> >> The lines could be changed to: > >> >> > >> >> if(length(justify) != 2) > >> >> stop("justify must be length 2") > >> >> cbind(apply(LABS, 2L, format, justify = justify[1]), > >> >> apply(DATA, 2L, format, justify = justify[2])) > >> >> > >> >> The argument justify could defaults to c("left", "right") for > backward compatibility. > >> >> > >> >> It could then allow: > >> >> ftab <- ftable(wool + tension ~ breaks, warpbreaks) > >> >> format.ftable(ftab, justify = c("none", "none")) > >> >> > >> >> Best regards, > >> >> > >> >> Thomas > > > > -- > > Statistics & Software Consulting > > GKX Group, GKX Associates Inc. > > tel: 1-877-GKX-GROUP > > email: ggrothendieck at gmail.com -- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel