R help - Feb 2012 - How to retrieve a column name of a data frame

Hi, 

I 'd like to know how to retrieve a column name of a data frame. For
instance :

df = data.frame(c1=c('a','b'),c2=c(1,2))
> df
  c1 c2
1  a  1
2  b  2

I would like to retrieve the column name which value is 2 (here, the column
is c2)

thanks for your help

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colnames(df)[2]

Michael

On Thu, Feb 2, 2012 at 10:31 AM, ikuzar <razuki at hotmail.fr>
wrote:
> Hi,
>
> I 'd like to know how to retrieve a column name of a data frame. For
> instance :
>
> df = data.frame(c1=c('a','b'),c2=c(1,2))
>> df
> ?c1 c2
> 1 ?a ?1
> 2 ?b ?2
>
> I would like to retrieve the column name which value is 2 (here, the column
> is c2)
>
> thanks for your help
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/How-to-retrieve-a-column-name-of-a-data-frame-tp4351764p4351764.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

> colnames( df )[2]
[1] "c2"  


On Thursday 02 February 2012 07:31:33 ikuzar wrote:
> Hi,
> 
> I 'd like to know how to retrieve a column name of a data frame. For
> instance :
> 
> df = data.frame(c1=c('a','b'),c2=c(1,2))
> 
> > df
> 
>   c1 c2
> 1  a  1
> 2  b  2
> 
> I would like to retrieve the column name which value is 2 (here, the column
> is c2)
> 
> thanks for your help
> 
> --
> View this message in context:
> http://r.789695.n4.nabble.com/How-to-retrieve-a-column-name-of-a-data-frame
> -tp4351764p4351764.html Sent from the R help mailing list archive at
> Nabble.com.
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.