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

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

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

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