Source code for pyspark.pandas.extensions

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from typing import Callable, Generic, Optional, Type, Union, TYPE_CHECKING
import warnings

from pyspark.pandas._typing import T

if TYPE_CHECKING:
    from pyspark.pandas.frame import DataFrame
    from pyspark.pandas.indexes import Index
    from pyspark.pandas.series import Series


class CachedAccessor(Generic[T]):
    """
    Custom property-like object.

    A descriptor for caching accessors:

    Parameters
    ----------
    name : str
        Namespace that accessor's methods, properties, etc will be accessed under, e.g. "foo" for a
        dataframe accessor yields the accessor ``df.foo``
    accessor: cls
        Class with the extension methods.

    Notes
    -----
    For accessor, the class's __init__ method assumes that you are registering an accessor for one
    of ``Series``, ``DataFrame``, or ``Index``.

    This object is not meant to be instantiated directly. Instead, use register_dataframe_accessor,
    register_series_accessor, or register_index_accessor.

    The pandas-on-Spark accessor is modified based on pandas.core.accessor.
    """

    def __init__(self, name: str, accessor: Type[T]) -> None:
        self._name = name
        self._accessor = accessor

    def __get__(
        self, obj: Optional[Union["DataFrame", "Series", "Index"]], cls: Type[T]
    ) -> Union[T, Type[T]]:
        if obj is None:
            return self._accessor
        accessor_obj = self._accessor(obj)  # type: ignore[call-arg]
        object.__setattr__(obj, self._name, accessor_obj)
        return accessor_obj


def _register_accessor(
    name: str, cls: Union[Type["DataFrame"], Type["Series"], Type["Index"]]
) -> Callable[[Type[T]], Type[T]]:
    """
    Register a custom accessor on {klass} objects.

    Parameters
    ----------
    name : str
        Name under which the accessor should be registered. A warning is issued if this name
        conflicts with a preexisting attribute.

    Returns
    -------
    callable
        A class decorator.

    See Also
    --------
    register_dataframe_accessor: Register a custom accessor on DataFrame objects
    register_series_accessor: Register a custom accessor on Series objects
    register_index_accessor: Register a custom accessor on Index objects

    Notes
    -----
    When accessed, your accessor will be initialiazed with the pandas-on-Spark object the user
    is interacting with. The code signature must be:

    .. code-block:: python

        def __init__(self, pandas_on_spark_obj):
            # constructor logic
        ...

    In the pandas API, if data passed to your accessor has an incorrect dtype, it's recommended to
    raise an ``AttributeError`` for consistency purposes. In pandas-on-Spark, ``ValueError`` is more
    frequently used to annotate when a value's datatype is unexpected for a given method/function.

    Ultimately, you can structure this however you like, but pandas-on-Spark would likely do
    something like this:

    >>> ps.Series(['a', 'b']).dt
    ...
    Traceback (most recent call last):
        ...
    ValueError: Cannot call DatetimeMethods on type StringType()

    Note: This function is not meant to be used directly - instead, use register_dataframe_accessor,
    register_series_accessor, or register_index_accessor.
    """

    def decorator(accessor: Type[T]) -> Type[T]:
        if hasattr(cls, name):
            msg = (
                "registration of accessor {0} under name '{1}' for type {2} is overriding "
                "a preexisting attribute with the same name.".format(accessor, name, cls.__name__)
            )

            warnings.warn(
                msg,
                UserWarning,
                stacklevel=2,
            )
        setattr(cls, name, CachedAccessor(name, accessor))
        return accessor

    return decorator


[docs]def register_dataframe_accessor(name: str) -> Callable[[Type[T]], Type[T]]: """ Register a custom accessor with a DataFrame Parameters ---------- name : str name used when calling the accessor after its registered Returns ------- callable A class decorator. See Also -------- register_series_accessor: Register a custom accessor on Series objects register_index_accessor: Register a custom accessor on Index objects Notes ----- When accessed, your accessor will be initialiazed with the pandas-on-Spark object the user is interacting with. The accessor's init method should always ingest the object being accessed. See the examples for the init signature. In the pandas API, if data passed to your accessor has an incorrect dtype, it's recommended to raise an ``AttributeError`` for consistency purposes. In pandas-on-Spark, ``ValueError`` is more frequently used to annotate when a value's datatype is unexpected for a given method/function. Ultimately, you can structure this however you like, but pandas-on-Spark would likely do something like this: >>> ps.Series(['a', 'b']).dt ... Traceback (most recent call last): ... ValueError: Cannot call DatetimeMethods on type StringType() Examples -------- In your library code:: from pyspark.pandas.extensions import register_dataframe_accessor @register_dataframe_accessor("geo") class GeoAccessor: def __init__(self, pandas_on_spark_obj): self._obj = pandas_on_spark_obj # other constructor logic @property def center(self): # return the geographic center point of this DataFrame lat = self._obj.latitude lon = self._obj.longitude return (float(lon.mean()), float(lat.mean())) def plot(self): # plot this array's data on a map pass Then, in an ipython session:: >>> ## Import if the accessor is in the other file. >>> # from my_ext_lib import GeoAccessor >>> psdf = ps.DataFrame({"longitude": np.linspace(0,10), ... "latitude": np.linspace(0, 20)}) >>> psdf.geo.center # doctest: +SKIP (5.0, 10.0) >>> psdf.geo.plot() # doctest: +SKIP """ from pyspark.pandas import DataFrame return _register_accessor(name, DataFrame)
[docs]def register_series_accessor(name: str) -> Callable[[Type[T]], Type[T]]: """ Register a custom accessor with a Series object Parameters ---------- name : str name used when calling the accessor after its registered Returns ------- callable A class decorator. See Also -------- register_dataframe_accessor: Register a custom accessor on DataFrame objects register_index_accessor: Register a custom accessor on Index objects Notes ----- When accessed, your accessor will be initialiazed with the pandas-on-Spark object the user is interacting with. The code signature must be:: def __init__(self, pandas_on_spark_obj): # constructor logic ... In the pandas API, if data passed to your accessor has an incorrect dtype, it's recommended to raise an ``AttributeError`` for consistency purposes. In pandas-on-Spark, ``ValueError`` is more frequently used to annotate when a value's datatype is unexpected for a given method/function. Ultimately, you can structure this however you like, but pandas-on-Spark would likely do something like this: >>> ps.Series(['a', 'b']).dt ... Traceback (most recent call last): ... ValueError: Cannot call DatetimeMethods on type StringType() Examples -------- In your library code:: from pyspark.pandas.extensions import register_series_accessor @register_series_accessor("geo") class GeoAccessor: def __init__(self, pandas_on_spark_obj): self._obj = pandas_on_spark_obj @property def is_valid(self): # boolean check to see if series contains valid geometry return True Then, in an ipython session:: >>> ## Import if the accessor is in the other file. >>> # from my_ext_lib import GeoAccessor >>> psdf = ps.DataFrame({"longitude": np.linspace(0,10), ... "latitude": np.linspace(0, 20)}) >>> psdf.longitude.geo.is_valid # doctest: +SKIP True """ from pyspark.pandas import Series return _register_accessor(name, Series)
[docs]def register_index_accessor(name: str) -> Callable[[Type[T]], Type[T]]: """ Register a custom accessor with an Index Parameters ---------- name : str name used when calling the accessor after its registered Returns ------- callable A class decorator. See Also -------- register_dataframe_accessor: Register a custom accessor on DataFrame objects register_series_accessor: Register a custom accessor on Series objects Notes ----- When accessed, your accessor will be initialiazed with the pandas-on-Spark object the user is interacting with. The code signature must be:: def __init__(self, pandas_on_spark_obj): # constructor logic ... In the pandas API, if data passed to your accessor has an incorrect dtype, it's recommended to raise an ``AttributeError`` for consistency purposes. In pandas-on-Spark, ``ValueError`` is more frequently used to annotate when a value's datatype is unexpected for a given method/function. Ultimately, you can structure this however you like, but pandas-on-Spark would likely do something like this: >>> ps.Series(['a', 'b']).dt ... Traceback (most recent call last): ... ValueError: Cannot call DatetimeMethods on type StringType() Examples -------- In your library code:: from pyspark.pandas.extensions import register_index_accessor @register_index_accessor("foo") class CustomAccessor: def __init__(self, pandas_on_spark_obj): self._obj = pandas_on_spark_obj self.item = "baz" @property def bar(self): # return item value return self.item Then, in an ipython session:: >>> ## Import if the accessor is in the other file. >>> # from my_ext_lib import CustomAccessor >>> psdf = ps.DataFrame({"longitude": np.linspace(0,10), ... "latitude": np.linspace(0, 20)}) >>> psdf.index.foo.bar # doctest: +SKIP 'baz' """ from pyspark.pandas import Index return _register_accessor(name, Index)
def _test() -> None: import os import doctest import sys import numpy from pyspark.sql import SparkSession import pyspark.pandas.extensions os.chdir(os.environ["SPARK_HOME"]) globs = pyspark.pandas.extensions.__dict__.copy() globs["np"] = numpy globs["ps"] = pyspark.pandas spark = ( SparkSession.builder.master("local[4]") .appName("pyspark.pandas.extensions tests") .getOrCreate() ) (failure_count, test_count) = doctest.testmod( pyspark.pandas.extensions, globs=globs, optionflags=doctest.ELLIPSIS | doctest.NORMALIZE_WHITESPACE, ) spark.stop() if failure_count: sys.exit(-1) if __name__ == "__main__": _test()