Please see in line. On Fri, Jan 11, 2013 at 10:07 AM, Martin Batholdy <batho...@googlemail.com> wrote: > Hi, > > When using the aggregate function to aggregate a data.frame by one or more > grouping variables I often have the problem, that I want the mean for some > numeric variables but the unique value for factor variables. > > So for example in this data-frame: > > data <- data.frame(x = rnorm(10,1,2), group = c(rep(1,5), rep(2,5)), gender > =c(rep('m',5), rep('f',5))) > aggregate(data, by=list(data$group), FUN=mean) > > > I would like to have 'm' and 'f' in the third column, not NA. > > > I see the problem, that it could happen that there is no unique factor level > in a group – > but is there an alternative function who at least tries what I am aiming at? > > That is; > > "aggregate the data.frame by a list of grouping variables, > for numeric variables compute the mean, > for factor variables return the unique factor value"
R is a language, so you just have to do the translation: mt <- function(x) { if(is.numeric(x)) { # if x is numeric return(mean(x)) # compute the mean } else { # otherwise tab <- table(x) # tabulate x return(paste(paste(names(tab), # and format it for display tab, sep=": "), collapse=", ")) } } aggregate(Dat, by=list(Dat$group), FUN=mt) Best, Ista > > > Thanks! > ______________________________________________ > 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. ______________________________________________ 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.