# Working with many models

```{r setup-model, include=FALSE}
library(purrr)
set.seed(1014)
options(digits = 3)
```

i.e. how do tidyr, dplyr and purrr intersect.

* Why use a data frame?
* List columns in a data frame
* Mutate & filter.
* Creating list columns with `group_by()` and `do()`.