This does the summation you want in one line: #create example data and column selection d = as.data.frame(matrix(rnorm(50),ncol=5)) cols = c(1,3)
#sum selected columns and put results in new row d[nrow(d)+1,cols] = colSums(d[,cols]) However, I would agree with the sentiments that this is a bad idea; far better to have the mean values stored in a new object leaving the original data table untainted. > On 31 Mar 2017, at 17:20, Bruce Ratner PhD <b...@dmstat1.com> wrote: > > Hi R'ers: > Given a data.frame of five columns and ten rows. > I would like to take the sum of, say, the first and third columns only. > For the remaining columns, I do not want any calculations, thus rending their > "values" on the "total" row blank. The sum/total row is to be combined to the > original data.frame, yielding a data.frame with five columns and eleven rows. > > Thanks, in advance. > Bruce > > > ______________ > Bruce Ratner PhD > The Significant Statistician™ > > > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
