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

[Boris Steipe]

Ah - that's an excellent point. Thanks.



> On Oct 28, 2023, at 14:54, Jeff Newmiller <jdnewmil using dcn.davis.ca.us> 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.