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

[Sarah Goslee]

On Tue, Nov 15, 2011 at 11:23 AM, Joshua Wiley <jwiley.psych at gmail.com> wrote:
> Hi,
>
> Look at ?"["
>
> anadata <- newdata[, cmn]
> ## i.e., extract all rows (the first argument is empty of the 2 column
> anadata <- newdata[, 2]

Or, if this is part of a more general problem and the column names are
not necessarily in sequence:

> newdata <- data.frame(V1=1:3, V2=4:6, V3=7:9)
> newdata[, paste("V", 2, sep="")]
[1] 4 5 6

Sarah

> Hope this helps,
>
> Josh
>
> On Tue, Nov 15, 2011 at 8:02 AM, haohao Tsing <haohaorain at gmail.com> 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
>>
>> how can I finish this command ?can anyone help me ? thank yo .

-- 
Sarah Goslee
http://www.functionaldiversity.org