> Hello R-users > The help I received from Petr helped me created this solution to my problems. > > t1<-with(mydata ,aggregate(mydata$Y, > list(mydata$time,mydata$treatment, mydata$expREP, mydata$techREP) , > median, na.rm=T)) ### find median by factors #### > > colnames(t1)<-c("time","treatment","expREP","techREP","Y50") ### column name > ## > > newdata<-merge(mydata, t1, by.x= names(mydata)[2:5], > by.y=names(t1)[1:4], all=T) >
Another way is to use the reshape package, http://had.co.nz/reshape library(reshape) molten <- melt(mydata, m="log2Abun") cast(molten, time + treatment + expREP + techREP ~ ., median) # You can also create many other "shapes" easily: cast(molten, expREP + techREP ~ time + treatment , median) cast(molten, expREP + techREP ~ time + treatment , median, margins=TRUE) Hadley ______________________________________________ R-help@stat.math.ethz.ch 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.