R function to keep rows belonging to top n groups of a certain column

keep_top_n.R

library(tidyverse)

keep_top_n <- function(df, col, n = 10) {
  semi_join(df, head(count_(df, col, sort = TRUE), n))
}

data(mpg)
# All car models
mpg %>% nrow()
# Just car models of top three manufacturers
mpg %>% keep_top_n(~manufacturer, 3) %>% nrow()