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}'" ... )