Thank you, the last is exactly what I was looking for. On Tue, Oct 24, 2023 at 2:41 PM Sarah Goslee <sarah.gos...@gmail.com> wrote: > > Hi, > > I think you're misunderstanding which set of variables go on either > side of the formula. > > Is this what you're looking for? > > > aggregate(OD ~ Time + Target + Conc, data = df, FUN = "mean") > Time Target Conc OD > 1 1 BACT 1 765.3333 > 2 1 BACT 2 745.3333 > 3 1 BACT 3 675.0000 > > aggregate(ODnorm ~ Time + Target + Conc, data = df, FUN = "mean") > Time Target Conc ODnorm > 1 1 BACT 1 108.33333 > 2 1 BACT 2 88.33333 > 3 1 BACT 3 18.00000 > > Or using a different form, that might be more straightforward to you: > > > aggregate(df[, c("OD", "ODnorm")], by = df[, c("Time", "Target", "Conc")], > > data = df, FUN = "mean") > Time Target Conc OD ODnorm > 1 1 BACT 1 765.3333 108.33333 > 2 1 BACT 2 745.3333 88.33333 > 3 1 BACT 3 675.0000 18.00000 > > Sarah > > On Tue, Oct 24, 2023 at 8:31 AM Luigi Marongiu <marongiu.lu...@gmail.com> > wrote: > > > > Hello, > > I have a data frame with different groups (Time, Target, Conc) and > > each entry has a triplicate value of the measurements OD and ODnorm. > > How can I merge the triplicates into a single mean value? > > I tried the following: > > ``` > > df = data.frame(Time=rep(1, 9), Well=paste("A", 1:9, sep=""), > > OD=c(666, 815, 815, 702, 739, 795, 657, 705, 663), > > Target=rep("BACT", 9), > > Conc=c(1,1,1,2,2,2,3,3,3), > > ODnorm=c(9, 158, 158, 45, 82, 138, 0, 48, 6), > > stringsAsFactors = FALSE) > > aggregate(.~ODnorm, df, mean) > > > > > aggregate(.~ODnorm, df, mean) > > ODnorm Time Well OD Target Conc > > 1 0 NA NA NA NA NA > > 2 6 NA NA NA NA NA > > 3 9 NA NA NA NA NA > > 4 45 NA NA NA NA NA > > 5 48 NA NA NA NA NA > > 6 82 NA NA NA NA NA > > 7 138 NA NA NA NA NA > > 8 158 NA NA NA NA NA > > > > aggregate(cbind(Time, Target, Conc) ~ ODnorm, df, mean) > > ODnorm Time Target Conc > > 1 0 NA NA NA > > 2 6 NA NA NA > > 3 9 NA NA NA > > 4 45 NA NA NA > > 5 48 NA NA NA > > 6 82 NA NA NA > > 7 138 NA NA NA > > 8 158 NA NA NA > > ``` > > > > Thank you. > > > > ______________________________________________ > > 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. > > > > -- > Sarah Goslee (she/her) > http://www.numberwright.com
-- Best regards, Luigi ______________________________________________ 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.