I'm cleaning up the data set and I need to retain only those which repeated 4 times(like "a" and "b"), however, I am unable to do this. Can anyone please help?
Thank you!
let <- c("a","a","a","a","b","b","b","b","c","c","c","d","d","e")
avg <- c(1,1,1,2,3,4,5,6,1,2,3,4,3,5)
sample <- data.frame(let,avg)