[Rd] Notes on bug reports 3229 and 3242 - as.matrix.data.fram e

[Liaw, Andy]

> From: Gorjanc Gregor
> 
> ! Look after character !
> 
> From: Prof Brian Ripley [mailto:ripley at stats.ox.ac.uk]
> You too have not give an reproducible example!
> ! Yes, I was not able to do it from my data. But bellow is one. It is
> ! a stupid one, but it works. The problem is use of as.data.frame in 
> ! tmp1$L <- as.data.frame(tmp$L). This looks like to produce 
> a corrupted
> ! data.frame. If I use just tmp1$L <- tmp$L, write.table and 
> ! as.matrix.data.frame works OK. I still think that mine proposal can
> ! give benefit, since it works also on corrupted data frames.
> 
> data(warpbreaks)
> tmp <- as.data.frame(tapply(breaks, list(wool, tension), mean))
> tmp1 <- data.frame(level=rownames(tmp))
> tmp1$L <- as.data.frame(tmp$L)

Here's the problem that Brian is referring to:  Why do you make one variable
in the data frame a data frame?  That's what caused problem in
write.table()!

Andy


> write.table(tmp1)
> Error in as.matrix.data.frame(x) : dim<- : dims [product 2] 
> do not match the length of object [3]
> 
> tmp1$L <- tmp$L
> write.table(tmp1)
> "level" "L"
> "1" "A" 44.55556
> "2" "B" 28.22222
> 
> If you have a corrupt data frame, the function may fail, 
> which is what 
> happened in the PR# you quote.
> 
> Please note: you should not be calling as.matrix.data.frame, 
> but as.matrix.
> ! I called it because I had problems with write.table and 
> that function
> ! calls as.matrix.data.frame. 
> 
> On Fri, 11 Feb 2005, Gorjanc Gregor wrote:
> 
> > Hello R developers.
> >
> > I encountered the same problem as Uwe Ligges with 
> as.matrix.data.frame()
> > in bug reports 3229 and 3242 - under section not-reproducible.
> >
> > Example I have is:
> >
> >> tmp
> >                             level 2100-D
> > 1       biological_process unknown     NA
> > 2                 cellular process  -5.88
> > 3                      development  -8.42
> > 4            physiological process  -6.55
> > 5 regulation of biological process     NA
> > 6                 viral life cycle     NA
> >
> >> str(tmp)
> > `data.frame':   6 obs. of  2 variables:
> > $ level      : Factor w/ 6 levels "biological_..",..: 1 2 3 4 5 6
> > $ 2100-D_mean:`data.frame':    6 obs. of  1 variable:
> >  ..$ 2100-D: num  NA -5.88 -8.42 -6.55 NA NA
> 
> I think you have a data frame column in a data frame, and 
> that cannot be 
> made directly into a matrix.  It's the steps that got you 
> here that are 
> the problem.
> 
> >> as.matrix.data.frame(tmp)
> > Error in as.matrix.data.frame(tmp) : dim<- : dims [product 6] do not
> > match the length of object [7]
> >
> > The error associated with this is comming up at the end of function
> > as.matrix.data.frame where it is used:
> >
> >    dim(X) <- c(n, length(X)/n)
> >
> > ?dim says
> >     'dim' has a method for 'data.frame's, which returns the 
> length of
> >     the 'row.names' attribute of 'x' and the length of 'x' (the
> >     numbers of "rows" and "columns").
> >
> > This part is ok. The problem is with X, which is "intensively"
> > modified through the function. Before this (dim(X) <- ...) call
> > X in my case is:
> >
> >> x <- tmp
> >> "code from as.matrix.data.frame down to dim(X) <- ..."
> >> X
> > [[1]]
> > [1] "biological_process unknown"
> >
> > [[2]]
> > [1] "cellular process"
> >
> > [[3]]
> > [1] "development"
> >
> > [[4]]
> > [1] "physiological process"
> >
> > [[5]]
> > [1] "regulation of biological process"
> >
> > [[6]]
> > [1] "viral life cycle"
> >
> > [[7]]
> > [1]    NA -5.88 -8.42 -6.55    NA    NA
> >
> > So we can see, that X is somehow destroyed - the first and second
> > column of tmp differ. For dim command this should really be one
> > long vector. So the problem lies in line
> >
> >    X <- unlist(X, recursive = FALSE, use.names = FALSE)
> >
> > where it should be
> >
> >    X <- unlist(X, recursive = TRUE, use.names = FALSE)
> >                               ^^^^
> >
> > I have checked source code for that function from R as well as
> > in R-devel sources. I was not succesfull in reproducing the above
> > with the data frame bellow though. It did not report any problems
> > with old as.matrix.data.frame. There must be some trick with
> > first column in my data. So I am quite sure my suggestion is
> > OK.
> >
> > tmp1 <- data.frame(level=c("A A", "B B"), x=c(NA, -5.8))
> >
> > --
> > Lep pozdrav / With regards,
> >    Gregor GORJANC
> >
> > ---------------------------------------------------------------
> > University of Ljubljana
> > Biotechnical Faculty       URI: http://www.bfro.uni-lj.si
> > Zootechnical Department    email: gregor.gorjanc <at> bfro.uni-lj.si
> > Groblje 3                  tel: +386 (0)1 72 17 861
> > SI-1230 Domzale            fax: +386 (0)1 72 17 888
> > Slovenia
> >
> > ______________________________________________
> > R-devel at stat.math.ethz.ch mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-devel
> >
> >
> 
> -- 
> Brian D. Ripley,                  ripley at stats.ox.ac.uk
> Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
> University of Oxford,             Tel:  +44 1865 272861 (self)
> 1 South Parks Road,                     +44 1865 272866 (PA)
> Oxford OX1 3TG, UK                Fax:  +44 1865 272595
> 
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