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

You could do this using dplyr (assuming your data is in a data frame called dt:

dt %>% group_by(draw) %>% filter(n() >= 5) %>% ungroup()

Or you could use table or xtabs:

tab <- xtabs(~ draw, dt)

dt[!dt$draw %in% as.numeric(names(which(tab < 5))), ]