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# pandas.CategoricalIndex.reorder_categories

CategoricalIndex.reorder_categories(new_categories, ordered=None)

  Reorder categories as specified in new_categories.

  `new_categories` need to include all old categories and no new category items.

  Parameters:
    new_categories Index-like

      The categories in new order.

    ordered bool, optional

      Whether or not the categorical is treated as an ordered categorical. If not given, do not change the ordered information.

  Returns:
    Categorical

      Categorical with reordered categories.

  Raises:
    ValueError

      If the new categories do not contain all old category items or any new ones

  See also

  `rename_categories`

    Rename categories.

  `add_categories`

    Add new 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

  For `pandas.Series`:

      >>> ser = pd.Series(["a", "b", "c", "a"], dtype="category")
      >>> ser = ser.cat.reorder_categories(["c", "b", "a"], ordered=True)
      >>> ser
      0   a
      1   b
      2   c
      3   a
      dtype: category
      Categories (3, str): ['c' < 'b' < 'a']

      >>> ser.sort_values()
      2   c
      1   b
      0   a
      3   a
      dtype: category
      Categories (3, str): ['c' < 'b' < 'a']

  For `pandas.CategoricalIndex`:

      >>> ci = pd.CategoricalIndex(["a", "b", "c", "a"])
      >>> ci
      CategoricalIndex(['a', 'b', 'c', 'a'], categories=['a', 'b', 'c'],
                       ordered=False, dtype='category')
      >>> ci.reorder_categories(["c", "b", "a"], ordered=True)
      CategoricalIndex(['a', 'b', 'c', 'a'], categories=['c', 'b', 'a'],
                       ordered=True, dtype='category')