How to remove groups of observation with dplyr::filter()

Question

For the following data

ds <- read.table(header = TRUE, text =\"
id year attend
1 2007      1
1 2008      1
1 2009      1
1 2010      1
1 2011      1
8 200         


        

Answer 1

Use filter in conjunction with base::ave

ds %>% dplyr::filter(ave(!is.na(attend), id, FUN = all))

To obtain

    id year attend
 1   1 2007      1
 2   1 2008      1
 3   1 2009      1
 4   1 2010      1
 5   1 2011      1
 6   9 2007      2
 7   9 2008      3
 8   9 2009      3
 9   9 2010      5
 10  9 2011      5