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

[Duncan Murdoch]

On 28/10/2023 4:45 p.m., Bert Gunter wrote:
> 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.

Dataframes have to have column names.  The function isn't modifying the 
object any more than it has to.

Duncan Murdoch

> 
> 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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> 
> ______________________________________________
> 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.