Re: [R] How to obtain named vector from single-column data frame?
Dear David and Rui,
Thanks a lot to both of you for your very fast answers; problem solved! :)
Regards,
Guido
From: David Carlson
Sent: 06 May 2022 20:26
To: Hooiveld, Guido
Cc: r-help@r-project.org
Subject: Re: [R] How to obtain named vector from single-column data frame?
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
mailto: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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Re: [R] How to obtain named vector from single-column data frame?
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
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,
> ZjQcmQRYFpfptBannerStart
> This Message Is From an External Sender
> This message came from outside your organization.
>
> ZjQcmQRYFpfptBannerEnd
>
> 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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Re: [R] How to obtain named vector from single-column data frame?
Hello,
When you unlist, the dimension is dropped since the result is just one
vector. Add drop = FALSE and that's it.
unlist(df[, "VarY", drop = FALSE])
Hope this helps,
Rui Barradas
Às 19:05 de 06/05/2022, Hooiveld, Guido escreveu:
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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and provide commented, minimal, self-contained, reproducible code.
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