subset based on frequency level [duplicate]

Answer 1

Maybe closer to what you had in mind is to create a vector of frequencies using ave:

subset(df1, ave(ID, ID, FUN = length) > cutoff)

Answer 2

df1[ df1$ID %in%  names(table(df1$ID))[table(df1$ID) >9] , ]

This will test to see if the df1$ID value is in a category with more than 9 values. If it is, then the logical element for the returned vector will be TRUE and in turn that as the "i" argument will cause the [-function to return the entire row since the "j" item is empty.

See:

?`[`
?'%in%'

Answer 3

Using dplyr

library(dplyr)
 df1 %>% 
 group_by(ID) %>% 
 filter(n()>cutoff)