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builtins.object ABC BaseStringArrayMethods ObjectStringArrayMixin builtins.object DirNamesMixin PandasObject builtins.object ExtensionArray builtins.object NDArrayBacked NDArrayBackedExtensionArray Categorical
class Categorical(NDArrayBackedExtensionArray, PandasObject, ObjectStringArrayMixin):
Represent a categorical variable in classic R / S-plus fashion.
`Categoricals` can only take on a limited, and usually fixed, number
of possible values (`categories`). In contrast to statistical categorical
variables, a `Categorical` might have an order, but numerical operations
(additions, divisions, ...) are not possible.
All values of the `Categorical` are either in `categories` or `np.nan`.
Assigning values outside of `categories` will raise a `ValueError`. Order
is defined by the order of the `categories`, not lexical order of the
values.
Parameters
----------
values : list-like
The values of the categorical. If categories are given, values not in
categories will be replaced with NaN.
categories : Index-like (unique), optional
The unique categories for this categorical. If not given, the
categories are assumed to be the unique values of `values` (sorted, if
possible, otherwise in the order in which they appear).
ordered : bool, default False
Whether or not this categorical is treated as a ordered categorical.
If True, the resulting categorical will be ordered.
An ordered categorical respects, when sorted, the order of its
`categories` attribute (which in turn is the `categories` argument, if
provided).
dtype : CategoricalDtype
An instance of ``CategoricalDtype`` to use for this categorical.
Attributes
----------
categories : Index
The categories of this categorical.
codes : ndarray
The codes (integer positions, which point to the categories) of this
categorical, read only.
ordered : bool
Whether or not this Categorical is ordered.
dtype : CategoricalDtype
The instance of ``CategoricalDtype`` storing the ``categories``
and ``ordered``.
Methods
-------
from_codes
__array__
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
--------
CategoricalDtype : Type for categorical data.
CategoricalIndex : An Index with an underlying ``Categorical``.
Notes
-----
See the `user guide
<https://pandas.pydata.org/pandas-docs/stable/user_guide/categorical.html>`__
for more.
Examples
--------
>>> pd.Categorical([1, 2, 3, 1, 2, 3])
[1, 2, 3, 1, 2, 3]
Categories (3, int64): [1, 2, 3]
>>> pd.Categorical(['a', 'b', 'c', 'a', 'b', 'c'])
['a', 'b', 'c', 'a', 'b', 'c']
Categories (3, object): ['a', 'b', 'c']
Missing values are not included as a category.
>>> c = pd.Categorical([1, 2, 3, 1, 2, 3, np.nan])
>>> c
[1, 2, 3, 1, 2, 3, NaN]
Categories (3, int64): [1, 2, 3]
However, their presence is indicated in the `codes` attribute
by code `-1`.
>>> c.codes
array([ 0, 1, 2, 0, 1, 2, -1], dtype=int8)
Ordered `Categoricals` can be sorted according to the custom order
of the categories and can have a min and max value.
>>> c = pd.Categorical(['a', 'b', 'c', 'a', 'b', 'c'], ordered=True,
... categories=['c', 'b', 'a'])
>>> c
['a', 'b', 'c', 'a', 'b', 'c']
Categories (3, object): ['c' < 'b' < 'a']
>>> c.min()
'c'
| Nom de la propriété | Description |
|---|---|
| categories | |
| codes | |
| dtype | |
| nbytes | |
| ordered |
| Signature de l'opérateur | Description |
|---|---|
| __contains__(self, key) -> 'bool' |
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