pandas.api.extensions.ExtensionDtype — pandas 2.2.3 documentation (original) (raw)

class pandas.api.extensions.ExtensionDtype[source]#

A custom data type, to be paired with an ExtensionArray.

See also

extensions.register_extension_dtype

Register an ExtensionType with pandas as class decorator.

extensions.ExtensionArray

Abstract base class for custom 1-D array types.

Notes

The interface includes the following abstract methods that must be implemented by subclasses:

• type
• name
• construct_array_type

The following attributes and methods influence the behavior of the dtype in pandas operations

• _is_numeric
• _is_boolean
• _get_common_dtype

The na_value class attribute can be used to set the default NA value for this type. numpy.nan is used by default.

ExtensionDtypes are required to be hashable. The base class provides a default implementation, which relies on the _metadata class attribute. _metadata should be a tuple containing the strings that define your data type. For example, with PeriodDtype that’s the freq attribute.

If you have a parametrized dtype you should set the ``_metadata`` class property.

Ideally, the attributes in _metadata will match the parameters to your ExtensionDtype.__init__ (if any). If any of the attributes in _metadata don’t implement the standard__eq__ or __hash__, the default implementations here will not work.

Examples

For interaction with Apache Arrow (pyarrow), a __from_arrow__ method can be implemented: this method receives a pyarrow Array or ChunkedArray as only argument and is expected to return the appropriate pandas ExtensionArray for this dtype and the passed values:

import pyarrow from pandas.api.extensions import ExtensionArray class ExtensionDtype: ... def from_arrow( ... self, ... array: pyarrow.Array | pyarrow.ChunkedArray ... ) -> ExtensionArray: ... ...

This class does not inherit from ‘abc.ABCMeta’ for performance reasons. Methods and properties required by the interface raisepandas.errors.AbstractMethodError and no register method is provided for registering virtual subclasses.

Attributes

Methods