Dear David and Rui,

Thanks a lot to both of you for your very fast answers; problem solved! :)

Regards,
Guido

From: David Carlson <dcarl...@tamu.edu>
Sent: 06 May 2022 20:26
To: Hooiveld, Guido <guido.hooiv...@wur.nl>
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 
<guido.hooiv...@wur.nl<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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