You want this? > basicSubMean <- aggregate(basicSub[c("score")], by=list(basicSub$student), FUN=mean, na.rm=TRUE) > basicSubMean Group.1 score 1 1 55.0 2 2 60.0 3 3 67.5
bests milton On Sun, Jan 3, 2010 at 10:46 PM, david hilton shanabrook < dhsha...@acad.umass.edu> wrote: > I want to use aggregate with the mean function on specific columns > > gender <- factor(c("m", "m", "f", "f", "m")) > student <- c(0001, 0002, 0003, 0003, 0001) > score <- c(50, 60, 70, 65, 60) > basicSub <- data.frame(student, gender, score) > basicSubMean <- aggregate(basicSub, by=list(basicSub$student), FUN=mean, > na.rm=TRUE) > > This doesn't work, one cannot take the mean of a factor (gender). Is there > any way of specifying which columns to use for the mean? I want to > aggregate by student, obtaining mean scores, and assume any other factors > are unchanging in a specific student, ie. gender. > > Thanks > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html> > and provide commented, minimal, self-contained, reproducible code. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list 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.