[R] colnames of a column

[Alfredo Alessandrini]

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"



Thanks in advance,

Alfredo