忽略dplyr中带有n_distinct()的内容

Suppose I have this data set:

假设我有这个数据集:

test <- data.frame(thing = c(rep(1, 4), 
                         rep(2, 4), 
                         rep(3, 4), 
                         rep(4, 3), 
                         rep(5, 1)), 
                   thing2 = c(c("a", "b", "c", "c"), 
                              c("a", "b", "c", "d"),
                              c("a", "b", "b", "b"),
                              c("a", "b", "c"), 
                              c("d")))
te