How to delete groups containing less than 3 rows of data in R? -

this question has answer here:

• subset data frame based on number of rows per group 2 answers

i'm using dplyr package in r , have grouped data 3 variables (year, site, brood).

i want rid of groups made of less 3 rows. example in following sample remove rows brood '2'. have lot of data while painstakingly hand helpful automate using r.

year site brood parents 1996    1     1   1996    1     1   1996    1     0   1996    1     0   1996    2     1       1996    2     0   1996    3     1   1996    3     1   1996    3     1   1996    3     0   1996    3     1   

i hope makes sense , thank in advance help! i'm new r , stackoverflow apologies if way i've worded question isn't good! let me know if need provide other information.

one way use magic n() function within filter:

library(dplyr)  my_data <- data.frame(year=1996, site="a", brood=c(1,1,2,2,2))  my_data %>%    group_by(year, site, brood) %>%    filter(n() >= 3) 

the n() function gives number of rows in current group (or number of rows total if there no grouping).