Taking the sum of only some columns of a data frame
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 <br at 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 at 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.