I do not believe this can be done in one step dat <- data.frame(matrix(rnorm(50), 5))
pos <- c(1,3) res <- apply(dat[, pos], 2, sum) x <- numeric(5) x[pos] <- res rbind(dat,x) -----Original Message----- From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of Bruce Ratner PhD Sent: Friday, March 31, 2017 12:20 PM To: r-help@r-project.org Subject: [R] Taking the sum of only some columns of a data frame 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.