R delete rows in data frame where nrow of index is smaller than certain value

Question

I want to delete certain rows in a data frame when the number of rows with the same index is smaller than a pre-specified value.

> fof.6.5[1:15, 1:3]
   draw          


        

Answer 1

Code below makes that:

library(dplyr)
fof.6.5 <- data.frame(draw = rep(1:4, c(5, 5, 3, 2)),
                      Fun.ID = rnorm(15),
                      Firm.ID = rnorm(15))
fof_filter <- fof.6.5 %>% group_by(draw) %>% mutate(freq = n()) %>%
  filter(freq >= 5) %>% select(-freq)
fof_filter

• group_by join (in someway) profiles with the same value of draw
• mutate add a new variable "freq" that give the number of profiles per each group of draw and repeats it.
• filter selects only those profiles with "freq" greater or equals to 5
• select delete the "freq" column because is not needed anymore