Bill I ended up taking a different approach miDat <- miDat %>% mutate(new_cases = cases - lag(cases, default = 0))
- or - df <- df %>% mutate(diff = Score - lag(Score, default = 0)) Jeff -----Original Message----- From: William Michels <w...@caa.columbia.edu> Sent: Wednesday, March 24, 2021 1:41 PM To: r-help@r-project.org Cc: reichm...@sbcglobal.net; Gerrit Eichner <gerrit.eich...@math.uni-giessen.de> Subject: Re: [R] Calculating column differences More correctly, with an initial "NA" value in the "diff" column: > df <- data.frame(ID=1:5,Score=4*2:6) > df1 <- rbind(c(0,0), df) > cbind(df1, "diff"=c(NA, diff(df1$Score)) ) ID Score diff 1 0 0 NA 2 1 8 8 3 2 12 4 4 3 16 4 5 4 20 4 6 5 24 4 > HTH, Bill. On Wed, Mar 24, 2021 at 10:59 AM William Michels <w...@caa.columbia.edu> wrote: > > Dear Jeff, > > Rather than diff-ing a linear vector you're trying to diff values from > two different rows. Also you indicate that you want to place the > diff-ed value in the 'lower' row of a new column. Try this (note > insertion of an initial "zero" row): > > > df <- data.frame(ID=1:5,Score=4*2:6) > > df1 <- rbind(c(0,0), df) > > cbind(df1, "diff"=c(0, diff(df1$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.
