[R] how to indice the column in the data.frame

[David Winsemius]

On Nov 15, 2011, at 11:02 AM, haohao Tsing wrote:

> hi R,users
> Now I read a data from a txt file
> newdata<-read.table("1.txt")
> in the 1.txt ,there are several column shown as below
> 1 3 4 5
> 2 3 5 6
> 4 5 6 7
> so when I want analysis the second column
> anadata<-newdata$V2
>
> but my question I can not use some certain variable to indice the  
> column?
> e.g
> cmn=2
> anadata<-newdata$Vcmn

Either:

> anadata<-newdata[[ paste("V", cmn, sep="") ]]

Or:

> anadata<-newdata[[cmn]]


>
> how can I finish this command ?can anyone help me ? thank yo .

Your should go back and study your introductory manual now. If this is  
not near the begininning of that manual, you hsoulswitch manuals.

You should also type:

?"$"

And read that page carefully and try all of the examples. It will  
probably take more than one reading to master its contents, but it is  
a core part of learning R.

-- 

David Winsemius, MD
West Hartford, CT