Similar to dplyr::count(), but also adds the relative proportion and
a percent-formatted string of the relative proportion,
and allows to specify the column names.
Columns / expressions by which to group / which shall be used for counting.
column_names
vector if size 1 to 3, giving the names of (in order if unnamed, or named with n, rel, percent)
the column containing the count, the relative proportion, and the latter formatted as a percent label.
If a name is not contained, it will not be added (requires named vector).
percentage_label_decimal_places
Decimal precision of the percent label
add_grouping
Shall a pre-existing grouping be preserved for counting (adding the newly specified grouping)?
Default is yes, which differs from group_by.