Just use
names(unlist(df[, "VarY", drop=FALSE]))
# [1] "VarY1" "VarY2" "VarY3" "VarY4" "VarY5"
When you extract a single column from a data frame it converts it to a
vector by default.
David L Carlson
On Fri, May 6, 2022 at 1:05 PM Hooiveld, Guido <guido.hooiv...@wur.nl>
wrote:
> Dear all, I wrote a some code in which I 'convert' a data frame to a named
> vector using the function unlist(). This works very nicely for my use case,
> because each entry of the resulting vector is named after the column name
> of the data frame,
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> Dear all,
>
> I wrote a some code in which I 'convert' a data frame to a named vector using
> the function unlist(). This works very nicely for my use case, because each
> entry of the resulting vector is named after the column name of the data
> frame, with a number automatically appended. I am using these names for the
> subsequent part of my code.
>
> However, I noticed that when I subset the data frame so it contains only a
> single column, the naming of the vector (as described above) doesn't occur
> anymore (i.e. names() = NULL). This breaks my downstream code. Any suggestion
> on how to still obtain a named vector from such single-column data frame?
>
> Thanks,
> Guido
>
>
> > df <- data.frame("VarX" = c("A",2,"D",2,1) ,
> + "VarY" = c(5,7,9,8,7) )
> >
> > unlist(df) #nice!
> VarX1 VarX2 VarX3 VarX4 VarX5 VarY1 VarY2 VarY3 VarY4 VarY5
> "A" "2" "D" "2" "1" "5" "7" "9" "8" "7"
> > names(unlist(df))
> [1] "VarX1" "VarX2" "VarX3" "VarX4" "VarX5" "VarY1" "VarY2" "VarY3" "VarY4"
> [10] "VarY5"
> >
> >
> >
> > unlist(df[, "VarY"]) #where are the names now? Expected them to be "VarY1"
> > ... "VarY5"
> [1] 5 7 9 8 7
> > names(unlist(df[, "VarY"]))
> NULL
> >
>
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