map_df() from purrr applies a function across the inputs and combines the results into a data frame. Here, it checks the classes of six NBA variables at once. section 9.3
Inspecting NBA variable classes
After filtering the NBA data to 7,191 games and six columns, run `map_df(mydata, class)`. The result is a one-row tibble showing character columns for locations and results, and integer columns for days off. Convert those variables to factors with `as.factor()` before grouping and tallying home and away wins.
