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# pandas.CategoricalIndex.add_categories

CategoricalIndex.add_categories(*args, **kwargs)

  Add new categories.

  new_categories will be included at the last/highest place in the categories and will be unused directly after this call.

  Parameters:
    new_categoriescategory or list-like of category

      The new categories to be included.

  Returns:
    Categorical

      Categorical with new categories added.

  Raises:
    ValueError

      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.

  Examples

      >>> c = pd.Categorical(['c', 'b', 'c'])
      >>> c
      ['c', 'b', 'c']
      Categories (2, object): ['b', 'c']

      >>> c.add_categories(['d', 'a'])
      ['c', 'b', 'c']
      Categories (4, object): ['b', 'c', 'd', 'a']