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@jeroenjanssens
Created April 12, 2017 10:12
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R function to keep rows belonging to top n groups of a certain column
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()
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