group
Means for each level of a factor
Mon, 10/01/2007 - 16:54 — JeffA person on the R-Help list wanted to find the mean of each group, based on ID. Their data looked like:
data<-data.frame(ID=rep(letters[1:4], 5), size=runif(20))
The person was trying to write a for loop, as most people generally do when first encountering R (I sure did), but as is the case with most procedures in R, what can be done with a for loop in other languages, can be done looplessly in R.
