pandas.api.extensions.ExtensionDtype.construct_from_string

classmethod ExtensionDtype.construct_from_string(string)[source]

Construct this type from a string.

This is useful mainly for data types that accept parameters. For example, a period dtype accepts a frequency parameter that can be set as period[H] (where H means hourly frequency).

By default, in the abstract class, just the name of the type is expected. But subclasses can overwrite this method to accept parameters.

Parameters
stringstr

The name of the type, for example category.

Returns
ExtensionDtype

Instance of the dtype.

Raises
TypeError

If a class cannot be constructed from this ‘string’.

Examples

For extension dtypes with arguments the following may be an adequate implementation.

>>> @classmethod
... def construct_from_string(cls, string):
...     pattern = re.compile(r"^my_type\[(?P<arg_name>.+)\]$")
...     match = pattern.match(string)
...     if match:
...         return cls(**match.groupdict())
...     else:
...         raise TypeError(
...             f"Cannot construct a '{cls.__name__}' from '{string}'"
...         )