get rows of unique values by group

Question

I have a data.table and want to pick those lines of the data.table where some values of a variable x are unique relative to another variable y

It\'s possible to get

Answer 1

Thanks to dplyR

library(dplyr)
col1 = c(1,1,3,3,5,6,7,8,9)
col2 = c("cust1", 'cust1', 'cust3', 'cust4', 'cust5', 'cust5', 'cust5',     'cust5', 'cust6')
df1 = data.frame(col1, col2)
df1

distinct(select(df1, col1, col2))