Week 8: Joins and databases

DATA 412/612 · October 21

Lectures

• 8.1 dplyr: Keys and Mutating Joins(PDF)
• 8.2 dplyr: Filtering Joins(PDF)
• 8.3 dbplyr: Databases(PDF)

Labs

• Lab 8: Relational Data(PDF)
• Lab 8 solutions (password)

Additional readings

• R for Data Science: Joins
• STAT 545: Join cheatsheet
• dplyr: Two-table verbs
• here: Project-relative file paths

Discussion

• You inner_join() students to grades and lose rows. What happened, and which join would keep every student?
• What makes a good key? Give one bad key you might see in university data.