[R] colnames of a column

[Wacek Kusnierczyk]

Alfredo Alessandrini wrote:
> Hi,
>
> With this data.frame:
>
>   
>> class(rwl)
>>     
> [1] "data.frame"
>
>   
>> rwl
>>     
>   0028002F 0028013F 0028032F
> 1833     3.39       NA       NA
> 1834     3.09       NA       NA
> 1835     3.05       NA       NA
> 1836     3.31       NA       NA
> 1837     2.26       NA       NA
>
>   
>> colnames(rwl)
>>     
> [1] "0028002F" "0028013F" "0028032F"
>
> Ok....
>
>   
>> colnames(rwl[,1])
>>     
> NULL
>
> why?? I expect: "0028002F"
>
>   
have you read the docs?  start with ?`[`

you're yet another user confused by r's policy to drop dimensions as
soon as possible.
when you select one column from a data frame, you get a vector, not a
one-column data frame.
if you're always expecting a data frame while indexing, be sure to
include 'drop=FALSE':

> colnames(rwl[,1,drop=FALSE])
>   
[1] "0028002F"



vQ