[R] [Tagged] Re: col.names in as.data.frame() ?

[Bert Gunter]

Jeff, et. al. : but ...

Note that as.data.frame() *already* changes the matrix object by adding
column names of *its own choosing* when the matrix has none. So the issue
here is not *whether* col names should be added, but *what*/*how* they
should be. Unless you wish to extend your criticism to the current version
for its failure to adhere to your proscription.

Cheers,
Bert

On Sat, Oct 28, 2023 at 11:55 AM Jeff Newmiller via R-help <
r-help using r-project.org> wrote:

> as.data.frame is a _converter_, while data.frame is a _constructor_.
> Changing the object contents is not what a conversion is for.
>
> On October 28, 2023 11:39:22 AM PDT, Boris Steipe <
> boris.steipe using utoronto.ca> wrote:
> >Thanks Duncan and Avi!
> >
> >That you could use NULL in a matrix() dimnames = list(...) argument
> wasn't clear to me. I thought that would be equivalent to a one-element
> list - and thereby define rownames. So that's good to know.
> >
> >The documentation could be more explicit - but it is probably more work
> to do that than just patch the code to honour a col.names argument. (At
> least I can't see a reason not to.)
> >
> >Thanks again!
> >:-)
> >
> >
> >
> >
> >> On Oct 28, 2023, at 14:24, avi.e.gross using gmail.com wrote:
> >>
> >> Борис,
> >>
> >> Try this where you tell matrix the column names you want:
> >>
> >> nouns <- as.data.frame(
> >>  matrix(c(
> >>    "gaggle",
> >>    "geese",
> >>
> >>    "dule",
> >>    "doves",
> >>
> >>    "wake",
> >>    "vultures"
> >>  ),
> >>  ncol = 2,
> >>  byrow = TRUE,
> >>  dimnames=list(NULL, c("collective", "category"))))
> >>
> >> Result:
> >>
> >>> nouns
> >>  collective category
> >> 1     gaggle    geese
> >> 2       dule    doves
> >> 3       wake vultures
> >>
> >>
> >> The above simply names the columns earlier when creating the matrix.
> >>
> >> There are other ways and the way you tried LOOKS like it should work but
> >> fails for me with a message about it weirdly expecting three rows
> versus two
> >> which seems to confuse rows and columns. My version of R is recent and I
> >> wonder if there is a bug here.
> >>
> >> Consider whether you really need the data.frame created in a single
> >> statement or can you change the column names next as in:
> >>
> >>
> >>> nouns
> >>      V1       V2
> >> 1 gaggle    geese
> >> 2   dule    doves
> >> 3   wake vultures
> >>> colnames(nouns)
> >> [1] "V1" "V2"
> >>> colnames(nouns) <- c("collective", "category")
> >>> nouns
> >>  collective category
> >> 1     gaggle    geese
> >> 2       dule    doves
> >> 3       wake vultures
> >>
> >> Is there a known bug here or is the documentation wrong?
> >>
> >> -----Original Message-----
> >> From: R-help <r-help-bounces using r-project.org> On Behalf Of Boris Steipe
> >> Sent: Saturday, October 28, 2023 1:54 PM
> >> To: R. Mailing List <r-help using r-project.org>
> >> Subject: [R] col.names in as.data.frame() ?
> >>
> >> I have been trying to create a data frame from some structured text in a
> >> single expression. Reprex:
> >>
> >> nouns <- as.data.frame(
> >>  matrix(c(
> >>    "gaggle",
> >>    "geese",
> >>
> >>    "dule",
> >>    "doves",
> >>
> >>    "wake",
> >>    "vultures"
> >>  ), ncol = 2, byrow = TRUE),
> >>  col.names = c("collective", "category")
> >> )
> >>
> >> But ... :
> >>
> >>> str(nouns)
> >> 'data.frame': 3 obs. of  2 variables:
> >> $ V1: chr  "gaggle" "dule" "wake"
> >> $ V2: chr  "geese" "doves" "vultures"
> >>
> >> i.e. the col.names argument does nothing. From my reading of
> ?as.data.frame,
> >> my example should have worked.
> >>
> >> I know how to get the required result with colnames(), but I would like
> to
> >> understand why the idiom as written didn't work, and how I could have
> known
> >> that from the help file.
> >>
> >>
> >> Thanks!
> >> Boris
> >>
> >> ______________________________________________
> >> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> >> 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.
> >>
> >
> >______________________________________________
> >R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> >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.
>
> --
> Sent from my phone. Please excuse my brevity.
>
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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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