Week 4: dplyr: rows, columns, and groups

DATA 412/612 · September 23

Lectures

• 4.1 dplyr: Rows(PDF)
• 4.2 dplyr: Columns(PDF)
• 4.3 dplyr: Groups and Summaries(PDF)
• dplyr cheat sheet (Posit)

Labs

• Lab 4: dplyr, Part 1(PDF)
• Lab 4 solutions (password)

Practice

• Dplyr Practice: 10 Exercises with Solutions(.qmd)

Sample quiz

• Quiz 1, sample 1(PDF)
• Quiz 1, sample 2(PDF)

Additional readings

• R for Data Science: Data transformation
• Tidyverse Style Guide: Syntax
• STAT 545: Introduction to dplyr
• STAT 545: Single-table dplyr functions

Discussion

• If a table has extra rows, extra columns, and the wrong order, which dplyr verb would you use first, and why?
• Why does group_by() without a later summary or grouped mutate often surprise people?