pandas.CategoricalIndex#

classpandas.CategoricalIndex(data=None,categories=None,ordered=None,dtype=None,copy=False,name=None)[source]#

Index based on an underlyingCategorical.

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:

dataarray-like (1-dimensional)

The values of the categorical. Ifcategories are given, values not incategories will be replaced with NaN.

categoriesindex-like, optional

The categories for the categorical. Items need to be unique.If the categories are not given here (and also not indtype), theywill be inferred from thedata.

orderedbool, optional

Whether or not this categorical is treated as an orderedcategorical. If not given here or indtype, the resultingcategorical will be unordered.

dtypeCategoricalDtype or “category”, optional

IfCategoricalDtype, cannot be used together withcategories orordered.

copybool, default False

Make a copy of input ndarray.

nameobject, optional

Name to be stored in the index.

Attributes

codes	The category codes of this categorical index.
categories	The categories of this categorical.
ordered	Whether the categories have an ordered relationship.

Methods

rename_categories(*args, **kwargs)	Rename categories.
reorder_categories(*args, **kwargs)	Reorder categories as specified in new_categories.
add_categories(*args, **kwargs)	Add new categories.
remove_categories(*args, **kwargs)	Remove the specified categories.
remove_unused_categories(*args, **kwargs)	Remove categories which are not used.
set_categories(*args, **kwargs)	Set the categories to the specified new categories.
as_ordered(*args, **kwargs)	Set the Categorical to be ordered.
as_unordered(*args, **kwargs)	Set the Categorical to be unordered.
map(mapper[, na_action])	Map values using input an input mapping or function.

Raises:

ValueError

If the categories do not validate.

TypeError

If an explicitordered=True is given but nocategories and thevalues are not sortable.

See also

Index

The base pandas Index type.

Categorical

A categorical array.

CategoricalDtype

Type for categorical data.

Notes

See theuser guidefor more.

Examples

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

CategoricalIndex can also be instantiated from aCategorical:

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

OrderedCategoricalIndex can have a min and max value.

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