dplyr - filter by group size

Question

What is the best way to filter a data.frame to only get groups of say size 5?

So my data looks as follows:

require(dplyr)
n <- 1e5
x <- rnorm(n         


        

Answer 1

You can do it more concisely with n():

library(dplyr)
dat %>% group_by(cat) %>% filter(n() == 5)