R help - Nov 2009 - How to exclude certain columns by column names?

I can exclude columns by column number using '-'. But I wondering if
there is an easy way to exclude some columns by column names.
> x=cbind(c(1,2),c(3,4))
> x
     [,1] [,2]
[1,]    1    3
[2,]    2    4
> colnames(x)=c('a','b')
> x
     a b
[1,] 1 3
[2,] 2 4
> x[,-'a']
Error in -"a" : invalid argument to unary
operator
> x[,-1]
[1] 3 4

Hi Peng,

Here is a suggestion:

subset(x, select = -a)

See ?subset for more details.

HTH,
Jorge


On Mon, Nov 2, 2009 at 8:31 PM, Peng Yu <> wrote:
> I can exclude columns by column number using '-'. But I wondering
if
> there is an easy way to exclude some columns by column names.
>
> > x=cbind(c(1,2),c(3,4))
> > x
>     [,1] [,2]
> [1,]    1    3
> [2,]    2    4
> > colnames(x)=c('a','b')
> > x
>     a b
> [1,] 1 3
> [2,] 2 4
> > x[,-'a']
> Error in -"a" : invalid argument to unary operator
> > x[,-1]
> [1] 3 4
>
> ______________________________________________
> R-help@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.
>
	[[alternative HTML version deleted]]

Try this:
> x[, colnames(x) != 'a']
[1] 3 4

On Tue, Nov 3, 2009 at 9:31 AM, Peng Yu <pengyu.ut at gmail.com>
wrote:
> I can exclude columns by column number using '-'. But I wondering
if
> there is an easy way to exclude some columns by column names.
>
>> x=cbind(c(1,2),c(3,4))
>> x
> ? ? [,1] [,2]
> [1,] ? ?1 ? ?3
> [2,] ? ?2 ? ?4
>> colnames(x)=c('a','b')
>> x
> ? ? a b
> [1,] 1 3
> [2,] 2 4
>> x[,-'a']
> Error in -"a" : invalid argument to unary operator
>> x[,-1]
> [1] 3 4
>
> ______________________________________________
> 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.
>

Try this;

x[,setdiff(colnames(x), 'a')]


On Mon, Nov 2, 2009 at 11:31 PM, Peng Yu <pengyu.ut at gmail.com>
wrote:
> I can exclude columns by column number using '-'. But I wondering
if
> there is an easy way to exclude some columns by column names.
>
>> x=cbind(c(1,2),c(3,4))
>> x
> ? ? [,1] [,2]
> [1,] ? ?1 ? ?3
> [2,] ? ?2 ? ?4
>> colnames(x)=c('a','b')
>> x
> ? ? a b
> [1,] 1 3
> [2,] 2 4
>> x[,-'a']
> Error in -"a" : invalid argument to unary operator
>> x[,-1]
> [1] 3 4
>
> ______________________________________________
> 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.
>


-- 
Henrique Dallazuanna
Curitiba-Paran?-Brasil
25? 25' 40" S 49? 16' 22" O