Summarizing rows

Aggregate row values

We’ll use the {dplyr} summarise() functions to apply summary functions to data rows (e.g., mean(), min()). This is most useful when paired with group_by() to calculate summary values for each level in a group.

Learning objectives

• Summarize column values
• Start using summary functions
• Apply functions across columns
• Summarize separately for group levels
• Generate subsets of rows per group

Pre-meeting

To prepare for this class meeting, please do the following:

• Read R4DS2 4.4

Class meeting

• Counting rows per column level
• Summarizing column values across rows
• Summarizing multiple columns
• Grouping rows
• Summarizing groups of data
• Summarizing multiple groups
• Slicing rows per group
• Reviewing dplyr verbs
• Slides and Code

Homework after the class meeting

Wrap up this lesson

• Complete the exercises

For next class meeting

• Read R4DS2 6