how to indice the column in the data.frame

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Hi,

Look at ?"["

anadata <- newdata[, cmn]
## i.e., extract all rows (the first argument is empty of the 2 column
anadata <- newdata[, 2]

Hope this helps,

Josh
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 .

? ? ? ?[[alternative HTML version deleted]]

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Joshua Wiley
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University of California, Los Angeles
https://joshuawiley.com/
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

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