Series.cat.
add_categories
Add new categories.
new_categories will be included at the last/highest place in the categories and will be unused directly after this call.
The new categories to be included.
Whether or not to add the categories inplace or return a copy of this categorical with added categories.
If the new categories include old categories or do not validate as categories
See also
rename_categories
Rename categories.
reorder_categories
Reorder categories.
remove_categories
Remove the specified categories.
remove_unused_categories
Remove categories which are not used.
set_categories
Set the categories to the specified ones.