Grouped Up: group_by() → summarise() in R

We've built data frames, filtered, mutated and selected our way through messy data.

Today we crack open `group_by()` and `summarise()`
— how R silently splits your data into groups and collapses them into the numbers that matter.

We'll also start knocking out a few more essentials — string manipulation and other loose ends — before we level up into data visualization next week.

Bring your laptop, we code along live. 🧮