[R] Data frame vs matrix quirk: Hinky error message?
Nordlund, Dan (DSHS/RDA)
NordlDJ at dshs.wa.gov
Tue May 1 21:57:22 CEST 2012
Bert,
I think this is what is needed for the data frame
ix <- cbind(1:2,2:3)
ixm <- matrix(FALSE,4,3)
ixm[ix] <- TRUE
zdf[ixm] <- NA
Hope this is helpful,
Dan
Daniel J. Nordlund
Washington State Department of Social and Health Services
Planning, Performance, and Accountability
Research and Data Analysis Division
Olympia, WA 98504-5204
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Bert Gunter
> Sent: Tuesday, May 01, 2012 11:46 AM
> To: Duncan Murdoch
> Cc: r-help at r-project.org
> Subject: Re: [R] Data frame vs matrix quirk: Hinky error message?
>
> Duncan:
>
> Maybe there **is** a bug, then.
>
> > zmat <- matrix(1:12,nr=4)
> > zdf <- data.frame(zmat)
> > ix <- cbind(c(FALSE,TRUE),c(TRUE,TRUE))
> > zmat[ix]
> [1] 2 3 4 6 7 8 10 11 12
> > zdf[ix]
> [1] 2 3 4 6 7 8 10 11 12
> > zmat[ix] <- NA
> > zmat
> [,1] [,2] [,3]
> [1,] 1 5 9
> [2,] NA NA NA
> [3,] NA NA NA
> [4,] NA NA NA
>
> ## ??
>
> > zdf[ix] <- NA
> Error in `[<-.data.frame`(`*tmp*`, ix, value = NA) :
> only logical matrix subscripts are allowed in replacement
>
> That matrix replacement should not work with (in general mixed type)
> data frames seems reasonable, actually. Trying to "fix things" may not
> be. But I leave this to you and your fellow expeRts,
>
> Cheers,
> Bert
>
>
> On Tue, May 1, 2012 at 11:30 AM, Duncan Murdoch
> <murdoch.duncan at gmail.com> wrote:
> > On 01/05/2012 2:12 PM, Bert Gunter wrote:
> >>
> >> Many thanks, Ista:
> >>
> >> I only looked in "].default" so the answer is: Alternative 4: dumb
> >> Bert. Rap knuckles with ruler.
> >>
> >> Actually, indexing by a logical matrix doesn't make much sense to
> me
> >> in either case, as it does not have the effect of selecting
> individual
> >> elements, which is what numeric matrix indices do. But that's a
> matter
> >> of usage, neither bug nor feature.
> >>
> >> If I had gotten something like the error message: "Matrix indices
> not
> >> allowed for replacement in data frames," I would not have been
> >> surprised. But as you said, the behavior **IS** documented.
> >
> >
> > Your version is not correct: matrix indices *are* allowed for
> replacement,
> > but only logical matrix indices, not two column numerical ones. The
> > message might be clearer if instead of saying "only logical matrix
> > subscripts are allowed in replacement"
> > it said "matrix subscripts must be logical matrices in replacement",
> but I
> > think the basic problem is the limitation. I'll fix that.
> >
> > Duncan Murdoch
> >
> >>
> >> Best,
> >> Bert
> >>
> >>
> >>
> >> On Tue, May 1, 2012 at 10:49 AM, Ista Zahn<istazahn at gmail.com>
> wrote:
> >> > Hi Bert,
> >> >
> >> > The failure itself is the documented behavior: ?'[.data.frame'
> says
> >> >
> >> > "Matrix indexing ('x[i]' with a logical or a 2-column integer
> >> > matrix 'i') using '[' is not recommended, and barely
> supported.
> >> > For extraction, 'x' is first coerced to a matrix. For
> >> > replacement, a logical matrix (only) can be used to select
> the
> >> > elements to be replaced in the same way as for a matrix."
> >> >
> >> > The error message may be a bit hinky, as obviously data.frames
> can be
> >> > indexed by things other than logical matricies. Or is there
> another
> >> > reason this strikes you as odd?
> >> >
> >> > Best,
> >> > Ista
> >> >
> >> > On Tue, May 1, 2012 at 1:33 PM, Bert
> Gunter<gunter.berton at gene.com>
> >> > wrote:
> >> >> AdvisoRs:
> >> >>
> >> >> Is the following a bug, feature, hinky error message, or dumb
> Bert?
> >> >>
> >> >>> mtest<- matrix(1:12,nr=4)
> >> >>> dftest<- data.frame(mtest)
> >> >>> ix<- cbind(1:2,2:3)
> >> >>> mtest[ix]<- NA
> >> >>> mtest
> >> >> [,1] [,2] [,3]
> >> >> [1,] 1 NA 9
> >> >> [2,] 2 6 NA
> >> >> [3,] 3 7 11
> >> >> [4,] 4 8 12
> >> >>
> >> >> ## But ...
> >> >>> dftest[ix]<- NA
> >> >> Error in `[<-.data.frame`(`*tmp*`, ix, value = NA) :
> >> >> only logical matrix subscripts are allowed in replacement
> >> >>
> >> >> Obviously, I was expecting matrix indexing for replacement to
> work
> >> >> similarly in both cases; however, I can see why it would be
> >> >> problematic for data frames (mixed types), but was a bit
> nonplussed by
> >> >> the error message, which seems hinky to me.
> >> >>
> >> >> Cheers,
> >> >> Bert
> >> >>
> >> >> --
> >> >>
> >> >> Bert Gunter
> >> >> Genentech Nonclinical Biostatistics
> >> >>
> >> >> Internal Contact Info:
> >> >> Phone: 467-7374
> >> >> Website:
> >> >>
> >> >> http://pharmadevelopment.roche.com/index/pdb/pdb-functional-
> groups/pdb-biostatistics/pdb-ncb-home.htm
> >> >>
> >> >> ______________________________________________
> >> >> R-help at r-project.org mailing list
> >> >> https://stat.ethz.ch/mailman/listinfo/r-help
> >> >> PLEASE do read the posting guide
> >> >> http://www.R-project.org/posting-guide.html
> >> >> and provide commented, minimal, self-contained, reproducible
> code.
> >>
> >>
> >>
> >
>
>
>
> --
>
> Bert Gunter
> Genentech Nonclinical Biostatistics
>
> Internal Contact Info:
> Phone: 467-7374
> Website:
> http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-
> biostatistics/pdb-ncb-home.htm
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-
> guide.html
> and provide commented, minimal, self-contained, reproducible code.
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