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 .
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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 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 . > > ? ? ? ?[[alternative HTML version deleted]] > > ______________________________________________ > 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. >-- Joshua Wiley Ph.D. Student, Health Psychology Programmer Analyst II, ATS Statistical Consulting Group University of California, Los Angeles https://joshuawiley.com/
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
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$V2 > > but my question I can not use some certain variable to indice the > column? > e.g > cmn=2 > anadata<-newdata$VcmnEither:> 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