Check your understanding
Quiz
You have finished the join-and-reshape section: every join type, pivoting long and wide, splitting and uniting columns, and fuzzy matching. This quiz checks what stuck. The last two steps are live R.
Question 1 of 8
A left join with no match
You run left_join(customers, orders, by = "id"). A customer who has placed no orders will:
Correct: the left table is kept in full, with NA where the right side has no match.
A join matches on the key, it is not a cross product.