For a single dataframe, the tibble returned contains the columns:
type, a character vector containing the column types in df1.
cnt, integer counts of each type.
pcnt, the percentage of all columns with each type.
col_name, the names of columns with each type.
For a pair of dataframes, the tibble returned contains the columns:
type, a character vector containing the column types in
df1 and df2.
cnt_1, cnt_2, pair of integer columns containing counts of each type -
in each of df1 and df2
For a grouped dataframe, the tibble returned is as for a single dataframe, but where
the first k columns are the grouping columns. There will be as many rows in the result
as there are unique combinations of the grouping variables.