averaging rows on a data.frame according to a factor
Sorry, there's a bug in my previous answer.
dat <- data.frame(c("a","a","a","b","b"), c(1,2,3,3,2), c(4,3,5,4,4))
aggregate(as.matrix(dat[,-1]) ~ dat[,1], FUN = mean)
Don't use as.data.frame(cbind(...)), everything becomes factors.
Rui Barradas
Em 22-11-2013 23:02, Rui Barradas escreveu:
Hello, Try the following. aggregate(cbind(V2, V3) ~ V1, dat, FUN = mean) Hope this helps, Rui Barradas Em 22-11-2013 21:43, john d escreveu:
Dear all,
I apologize for the newbie question, but I'm stuck.
I have a data frame in the following form:
dat<-as.data.frame(cbind(c("a","a","a","b","b"),
c(1,2,3,3,2),c(4,3,5,4,4)))
I need a way to generate a new dataframe with the average for each
factor.
The result should look like:
res<-as.data.frame(cbind(c("a","b"), c(2,2.5),c(4,4)))
Any help would be greatly appreciated.
Jonathan
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