labels & annotations

A single annotated line

```{r}
#| code-line-style:
#|   - hi: { line: 4, label: "this is the bottleneck" }
```

df |>
  filter(cyl == 6) |>
  group_by(gear) |>
  summarise(m = mean(mpg)) |>
  arrange(desc(m))

Progressive annotations

Each step swaps the label.

```{r}
#| code-line-style:
#|   preset: emphasis
#|   steps:
#|     - focus: { line: 2, label: "1. filter the data" }
#|     - focus: { line: 3, label: "2. group it" }
#|     - focus: { line: 4, label: "3. summarise" }
#|     - focus: { line: 5, label: "4. order results" }
```

df |>
  filter(cyl == 6) |>
  group_by(gear) |>
  summarise(m = mean(mpg)) |>
  arrange(desc(m))