EagerPolarsDataset

EagerPolarsDataset loads and saves data using Polars in eager execution mode.

kedro_datasets.polars.EagerPolarsDataset

EagerPolarsDataset(
    *,
    filepath,
    file_format,
    load_args=None,
    save_args=None,
    version=None,
    credentials=None,
    fs_args=None,
    metadata=None
)

Bases: AbstractVersionedDataset[DataFrame, DataFrame]

polars.EagerPolarsDataset loads/saves data from/to a data file using an underlying filesystem (e.g.: local, S3, GCS). It uses polars to handle the dynamically select the appropriate type of read/write on a best effort basis.

Examples:

Using the YAML API:

cars:
  type: polars.EagerPolarsDataset
  file_format: parquet
  filepath: s3://data/01_raw/company/cars.parquet
  load_args:
    low_memory: True
  save_args:
    compression: "snappy"

Using the Python API:

>>> import polars as pl
>>> from kedro_datasets.polars import EagerPolarsDataset
>>>
>>> data = pl.DataFrame({"col1": [1, 2], "col2": [4, 5], "col3": [5, 6]})
>>>
>>> dataset = EagerPolarsDataset(filepath=tmp_path / "test.parquet", file_format="parquet")
>>> dataset.save(data)
>>> reloaded = dataset.load()
>>> assert data.equals(reloaded)

identified by string matching on a best effort basis.

Parameters:

• filepath (str) –

  Filepath in POSIX format to a file prefixed with a protocol like s3://. If prefix is not provided, file protocol (local filesystem) will be used. The prefix should be any protocol supported by fsspec. Key assumption: The first argument of either load/save method points to a filepath/buffer/io type location. There are some read/write targets such as 'clipboard' or 'records' that will fail since they do not take a filepath like argument.

• file_format (str) –

  String which is used to match the appropriate load/save method on a best effort basis. For example if 'csv' is passed, the polars.read_csv and polars.DataFrame.write_csv methods will be identified. An error will be raised unless there is at least one matching read_<file_format> or write_<file_format>.

• load_args (dict[str, Any] | None, default: None ) –

  Polars options for loading CSV files. Here you can find all available arguments: https://pola-rs.github.io/polars/py-polars/html/reference/io.html All defaults are preserved.

• save_args (dict[str, Any] | None, default: None ) –

  Polars options for saving files. Here you can find all available arguments: https://pola-rs.github.io/polars/py-polars/html/reference/io.html All defaults are preserved.

• version (Version | None, default: None ) –

  If specified, should be an instance of kedro.io.core.Version. If its load attribute is None, the latest version will be loaded. If its save attribute is None, save version will be autogenerated.

• credentials (dict[str, Any] | None, default: None ) –

  Credentials required to get access to the underlying filesystem. E.g. for GCSFileSystem it should look like {"token": None}.

• fs_args (dict[str, Any] | None, default: None ) –

  Extra arguments to pass into underlying filesystem class constructor (e.g. {"project": "my-project"} for GCSFileSystem).

• metadata (dict[str, Any] | None, default: None ) –

  Any arbitrary metadata. This is ignored by Kedro, but may be consumed by users or external plugins.

Raises: DatasetError: Will be raised if at least less than one appropriate read or write methods are identified.

Source code in kedro_datasets/polars/eager_polars_dataset.py

def __init__(  # noqa: PLR0913
    self,
    *,
    filepath: str,
    file_format: str,
    load_args: dict[str, Any] | None = None,
    save_args: dict[str, Any] | None = None,
    version: Version | None = None,
    credentials: dict[str, Any] | None = None,
    fs_args: dict[str, Any] | None = None,
    metadata: dict[str, Any] | None = None,
):
    """Creates a new instance of ``EagerPolarsDataset`` pointing to a concrete data file
    on a specific filesystem. The appropriate polars load/save methods are dynamically
    identified by string matching on a best effort basis.

    Args:
        filepath: Filepath in POSIX format to a file prefixed with a protocol like
            `s3://`.
            If prefix is not provided, `file` protocol (local filesystem)
            will be used.
            The prefix should be any protocol supported by ``fsspec``.
            Key assumption: The first argument of either load/save method points to
            a filepath/buffer/io type location. There are some read/write targets such
            as 'clipboard' or 'records' that will fail since they do not take a filepath
            like argument.
        file_format: String which is used to match the appropriate load/save method on a
            best effort basis. For example if 'csv' is passed, the `polars.read_csv` and
            `polars.DataFrame.write_csv` methods will be identified. An error will
            be raised unless there is at least one matching `read_<file_format>`
            or `write_<file_format>`.
        load_args: Polars options for loading CSV files.
            Here you can find all available arguments:
            https://pola-rs.github.io/polars/py-polars/html/reference/io.html
            All defaults are preserved.
        save_args: Polars options for saving files.
            Here you can find all available arguments:
            https://pola-rs.github.io/polars/py-polars/html/reference/io.html
            All defaults are preserved.
        version: If specified, should be an instance of
            ``kedro.io.core.Version``. If its ``load`` attribute is
            None, the latest version will be loaded. If its ``save``
            attribute is None, save version will be autogenerated.
        credentials: Credentials required to get access to the underlying filesystem.
            E.g. for ``GCSFileSystem`` it should look like `{"token": None}`.
        fs_args: Extra arguments to pass into underlying filesystem class constructor
            (e.g. `{"project": "my-project"}` for ``GCSFileSystem``).
        metadata: Any arbitrary metadata.
            This is ignored by Kedro, but may be consumed by users or external plugins.
    Raises:
        DatasetError: Will be raised if at least less than one appropriate read or write
            methods are identified.
    """

    self._file_format = file_format.lower()

    _fs_args = deepcopy(fs_args) or {}
    _fs_open_args_load = _fs_args.pop("open_args_load", {})
    _fs_open_args_save = _fs_args.pop("open_args_save", {})
    _credentials = deepcopy(credentials) or {}

    protocol, path = get_protocol_and_path(filepath)
    if protocol == "file":
        _fs_args.setdefault("auto_mkdir", True)

    self._protocol = protocol
    self._fs = fsspec.filesystem(self._protocol, **_credentials, **_fs_args)
    self.metadata = metadata

    super().__init__(
        filepath=PurePosixPath(path),
        version=version,
        exists_function=self._fs.exists,
        glob_function=self._fs.glob,
    )

    self._load_args = deepcopy(self.DEFAULT_LOAD_ARGS)
    if load_args is not None:
        self._load_args.update(load_args)
    self._save_args = deepcopy(self.DEFAULT_SAVE_ARGS)
    if save_args is not None:
        self._save_args.update(save_args)

    _fs_open_args_save.setdefault("mode", "wb")
    self._fs_open_args_load = _fs_open_args_load
    self._fs_open_args_save = _fs_open_args_save

DEFAULT_LOAD_ARGS class-attribute instance-attribute

DEFAULT_LOAD_ARGS = {}

DEFAULT_SAVE_ARGS class-attribute instance-attribute

DEFAULT_SAVE_ARGS = {}

_file_format instance-attribute

_file_format = lower()

_fs instance-attribute

_fs = filesystem(_protocol, **_credentials, **_fs_args)

_fs_open_args_load instance-attribute

_fs_open_args_load = _fs_open_args_load

_fs_open_args_save instance-attribute

_fs_open_args_save = _fs_open_args_save

_load_args instance-attribute

_load_args = deepcopy(DEFAULT_LOAD_ARGS)

_protocol instance-attribute

_protocol = protocol

_save_args instance-attribute

_save_args = deepcopy(DEFAULT_SAVE_ARGS)

metadata instance-attribute

metadata = metadata

_describe

_describe()

Source code in kedro_datasets/polars/eager_polars_dataset.py

def _describe(self) -> dict[str, Any]:
    return {
        "file_format": self._file_format,
        "filepath": self._filepath,
        "protocol": self._protocol,
        "load_args": self._load_args,
        "save_args": self._save_args,
        "version": self._version,
    }

_exists

_exists()

Source code in kedro_datasets/polars/eager_polars_dataset.py

def _exists(self) -> bool:
    try:
        load_path = get_filepath_str(self._get_load_path(), self._protocol)
    except DatasetError:
        return False

    return self._fs.exists(load_path)

_invalidate_cache

_invalidate_cache()

Invalidate underlying filesystem caches.

Source code in kedro_datasets/polars/eager_polars_dataset.py

def _invalidate_cache(self) -> None:
    """Invalidate underlying filesystem caches."""
    filepath = get_filepath_str(self._filepath, self._protocol)
    self._fs.invalidate_cache(filepath)

_release

_release()

Source code in kedro_datasets/polars/eager_polars_dataset.py

def _release(self) -> None:
    super()._release()
    self._invalidate_cache()

load

load()

Source code in kedro_datasets/polars/eager_polars_dataset.py

def load(self) -> pl.DataFrame:
    load_path = get_filepath_str(self._get_load_path(), self._protocol)
    load_method = getattr(pl, f"read_{self._file_format}", None)

    if not load_method:
        raise DatasetError(
            f"Unable to retrieve 'polars.read_{self._file_format}' method, please"
            " ensure that your "
            "'file_format' parameter has been defined correctly as per the Polars"
            " API"
            " https://pola-rs.github.io/polars/py-polars/html/reference/io.html"
        )
    with self._fs.open(load_path, **self._fs_open_args_load) as fs_file:
        return load_method(fs_file, **self._load_args)

save

save(data)

Source code in kedro_datasets/polars/eager_polars_dataset.py

def save(self, data: pl.DataFrame) -> None:
    save_path = get_filepath_str(self._get_save_path(), self._protocol)
    save_method = getattr(data, f"write_{self._file_format}", None)

    if not save_method:
        raise DatasetError(
            f"Unable to retrieve 'polars.DataFrame.write_{self._file_format}' "
            "method, please "
            "ensure that your 'file_format' parameter has been defined correctly as"
            " per the Polars API "
            "https://pola-rs.github.io/polars/py-polars/html/reference/io.html"
        )
    buf = BytesIO()
    save_method(buf, **self._save_args)
    with self._fs.open(save_path, **self._fs_open_args_save) as fs_file:
        fs_file.write(buf.getvalue())
        self._invalidate_cache()