Dear Kayj Try something like
setwd("c:\\temp") require(MASS) my.df<-read.table("my_inputfile.txt", sep="\t", head=T) my.df$newcol<-my.df$col1+my.df$col2+my.df$col3 write.table(my.df, "my_outputfile.txt", append=F, row.names=F, sep="\t") On the above example, I suppose that your input file are on c:\temp directory (pay attention on double slash); that you used TAB as field separator (sep="\t"); that the first line of your input file have the collumn names (head=T). my.df$newcol will create a new collumn on your data.frame and that it will receive the sum of other three collumns. write.table will save your new table. I hope this helps. miltinho astronauta Brazil On 8/27/08, kayj <[EMAIL PROTECTED]> wrote: > > > I do have some data of dim 100*3 (i.e 100 rows and 3 columns ) stored in a > txt file. I want to read the data into R, Perform the same operation in > each row and store the result in a forth column( that I should create). > I do not know how I can create a forth column to store the result of the > operation for each row? > > > > > > -- > View this message in context: > http://www.nabble.com/How-to-create-additional-columns--tp19191104p19191104.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > 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]] ______________________________________________ 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.