class pandas.api.extensions.ExtensionDtype[source]

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

See also


Register an ExtensionType with pandas as class decorator.


Abstract base class for custom 1-D array types.


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

  • type

  • name

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

  • _is_numeric

  • _is_boolean

  • _get_common_dtype

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: Union[pyarrow.Array, pyarrow.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.



A character code (one of ‘biufcmMOSUV’), default ‘O’


Default NA value to use for this type.


A string identifying the data type.


Ordered list of field names, or None if there are no fields.


The scalar type for the array, e.g.



Return the array type associated with this dtype.


Construct this type from a string.


Check if we match ‘dtype’.