Dear Jeff, Rather than diff-ing a linear vector you're trying to diff values from two different rows. Also you indicate that you want to place the diff-ed value in the 'lower' row of a new column. Try this (note insertion of an initial "zero" row):
> df <- data.frame(ID=1:5,Score=4*2:6) > df1 <- rbind(c(0,0), df) > cbind(df1, "diff"=c(0, diff(df1$Score)) ) ID Score diff 1 0 0 0 2 1 8 8 3 2 12 4 4 3 16 4 5 4 20 4 6 5 24 4 > HTH, Bill. W. Michels, Ph.D. On Wed, Mar 24, 2021 at 9:49 AM Jeff Reichman <reichm...@sbcglobal.net> wrote: > > r-help forum > > > > I'm trying to calculate the diff between two rows and them mutate the > difference into a new column. I'm using the diff function but not giving me > what I want. > > > > df <- data.frame(ID=1:5,Score=4*2:6) > > > > What a want where > > ID Score diff > > 1 1 8 8 > > 2 2 12 4 > > 3 3 16 4 > > 4 4 20 4 > > 5 5 24 4 > > > > What I am getting > > ID Score diff > > 1 1 8 NA > > 2 2 12 4 > > 3 3 16 4 > > 4 4 20 4 > > 5 5 24 4 > > > > Jeff > > > > > [[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.
