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

[@vi@e@gross m@iii@g oii gm@ii@com]

Jef, your terse reply was so constructive that you converted me! LOL!

That is an interesting point though that I remain a bit unclear on. 

Both data.frame and as.data.frame can be used in some ways similarly as in:

> data.frame(matrix(1:12, nrow=3))
  X1 X2 X3 X4
1  1  4  7 10
2  2  5  8 11
3  3  6  9 12

> as.data.frame(matrix(1:12, nrow=3))
  V1 V2 V3 V4
1  1  4  7 10
2  2  5  8 11
3  3  6  9 12

But yes, the constructor accepts many arguments  while the converter really normally handles a single object.

Where do some other things like cbind() fit, not to mention a dplyr function like tribble()?

I do wonder though, why asking a converter to convert a matrix to a data.frame and perhaps adding column names, is considered changing the object contents. The manual page for as.data.frame seems to include quite a few options to specify the name of a single column, truncate column names, deal with row names, and more as well as whether to convert strings to factors. Are those things different enough than what we are discussing?

Of course, we may indeed be experiencing mission creep where something simple keeps being improved with new features until the original simplicity and clarity gets lost.


-----Original Message-----
From: R-help <r-help-bounces using r-project.org> On Behalf Of Jeff Newmiller via R-help
Sent: Saturday, October 28, 2023 2:54 PM
To: r-help using r-project.org; Boris Steipe <boris.steipe using utoronto.ca>; R. Mailing List <r-help using r-project.org>
Subject: Re: [R] [Tagged] Re: col.names in as.data.frame() ?

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
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.