Class CategoricalIndex

pandas/core/indexes/category.py:78–552

Index based on an underlying :class:`Categorical`. CategoricalIndex, like Categorical, can only take on a limited, and usually fixed, number of possible values (`categories`). Also, like Categorical, it might have an order, but numerical operations (additions, divisions, ...) a

)
@set_module("pandas")
class CategoricalIndex(NDArrayBackedExtensionIndex):
    """
    Index based on an underlying :class:`Categorical`.

    CategoricalIndex, like Categorical, can only take on a limited,
    and usually fixed, number of possible values (`categories`). Also,
    like Categorical, it might have an order, but numerical operations
    (additions, divisions, ...) are not possible.

    Parameters
    ----------
    data : array-like (1-dimensional)
        The values of the categorical. If `categories` are given, values not in
        `categories` will be replaced with NaN.
    categories : index-like, optional
        The categories for the categorical. Items need to be unique.
        If the categories are not given here (and also not in `dtype`), they
        will be inferred from the `data`.
    ordered : bool, optional
        Whether or not this categorical is treated as an ordered
        categorical. If not given here or in `dtype`, the resulting
        categorical will be unordered.
    dtype : CategoricalDtype or "category", optional
        If :class:`CategoricalDtype`, cannot be used together with
        `categories` or `ordered`.
    copy : bool, default False
        Make a copy of input ndarray.
    name : object, optional
        Name to be stored in the index.

    Attributes
    ----------
    codes
    categories
    ordered

    Methods
    -------
    rename_categories
    reorder_categories
    add_categories
    remove_categories
    remove_unused_categories
    set_categories
    as_ordered
    as_unordered
    map

    Raises
    ------
    ValueError
        If the categories do not validate.
    TypeError
        If an explicit ``ordered=True`` is given but no `categories` and the
        `values` are not sortable.

    See Also
    --------