pandas.api.extensions.ExtensionDtype¶

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

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

New in version 0.23.0.

See also

extensions.register_extension_dtype
extensions.ExtensionArray

Notes

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

type
name
construct_from_string

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

_is_numeric
_is_boolean

Optionally one can override construct_array_type for construction with the name of this dtype via the Registry. See extensions.register_extension_dtype().

construct_array_type

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.

Changed in version 0.24.0: Added _metadata, __hash__, and changed the default definition of __eq__.

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:

class ExtensionDtype:

    def __from_arrow__(
        self, array: pyarrow.Array/ChunkedArray
    ) -> ExtensionArray:
        ...

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

Attributes

`kind`	A character code (one of ‘biufcmMOSUV’), default ‘O’
`na_value`	Default NA value to use for this type.
`name`	A string identifying the data type.
`names`	Ordered list of field names, or None if there are no fields.
`type`	The scalar type for the array, e.g.

Methods

`construct_array_type`()	Return the array type associated with this dtype.
`construct_from_string`(string)	Construct this type from a string.
`is_dtype`(dtype)	Check if we match ‘dtype’.