Hi:
Try this:
ratok <- data.frame(Id = rep(1:3, 3:1), value = c(2, 3, 4, 2, 1, 5))
aggregate(value ~ Id, data = ratok, FUN = mean)
Id value
1 1 3.0
2 2 1.5
3 3 5.0
aggregate() returns a data frame with the Id variable and mean(value).
HTH,
Dennis
On Sun, Oct 16, 2011 at 6:53 AM, Hel
if you set parameter simplify=TRUE, it returns a vector of the ragged
mean. In your case,
mean_rating <- tapply(ratok$value, ratok$project_id , mean,simplify = TRUE)
df<-data.frame(ID=dimnames(mean_rating)[[1]], mean=mean_rating)
Weidong Gu
On Sun, Oct 16, 2011 at 9:53 AM, Helene Schreyer
wrot
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