kedro.io.PickleLocalDataSet

class kedro.io.PickleLocalDataSet(filepath, backend='pickle', load_args=None, save_args=None, version=None)[source]

Bases: kedro.io.core.AbstractVersionedDataSet

PickleLocalDataSet loads and saves a Python object to a local pickle file. The underlying functionality is supported by the pickle and joblib libraries, so it supports all allowed options for loading and saving pickle files.

Example:

from kedro.io import PickleLocalDataSet
import pandas as pd

dummy_data =  pd.DataFrame({'col1': [1, 2],
                            'col2': [4, 5],
                            'col3': [5, 6]})
data_set = PickleLocalDataSet(filepath="data.pkl",
                              backend='pickle',
                              load_args=None,
                              save_args=None)
data_set.save(dummy_data)
reloaded = data_set.load()

Attributes

PickleLocalDataSet.BACKENDS
PickleLocalDataSet.DEFAULT_LOAD_ARGS
PickleLocalDataSet.DEFAULT_SAVE_ARGS

Methods

PickleLocalDataSet.__init__(filepath[, …]) Creates a new instance of PickleLocalDataSet pointing to a concrete filepath.
PickleLocalDataSet.exists() Checks whether a data set’s output already exists by calling the provided _exists() method.
PickleLocalDataSet.from_config(name, config) Create a data set instance using the configuration provided.
PickleLocalDataSet.get_last_load_version() Versioned datasets should override this property to return last loaded version
PickleLocalDataSet.get_last_save_version() Versioned datasets should override this property to return last saved version.
PickleLocalDataSet.load() Loads data by delegation to the provided load method.
PickleLocalDataSet.release() Release any cached data.
PickleLocalDataSet.save(data) Saves data by delegation to the provided save method.
BACKENDS = {'joblib': <module 'joblib' from '/home/docs/checkouts/readthedocs.org/user_builds/kedro/envs/latest/lib/python3.6/site-packages/joblib/__init__.py'>, 'pickle': <module 'pickle' from '/home/docs/.pyenv/versions/3.6.8/lib/python3.6/pickle.py'>}
DEFAULT_LOAD_ARGS = {}
DEFAULT_SAVE_ARGS = {}
__init__(filepath, backend='pickle', load_args=None, save_args=None, version=None)[source]

Creates a new instance of PickleLocalDataSet pointing to a concrete filepath. PickleLocalDataSet can use two backends to serialise objects to disk:

pickle.dump: https://docs.python.org/3/library/pickle.html#pickle.dump

joblib.dump: https://pythonhosted.org/joblib/generated/joblib.dump.html

and it can use two backends to load serialised objects into memory:

pickle.load: https://docs.python.org/3/library/pickle.html#pickle.load

joblib.load: https://pythonhosted.org/joblib/generated/joblib.load.html

Joblib tends to exhibit better performance in case objects store NumPy arrays: http://gael-varoquaux.info/programming/new_low-overhead_persistence_in_joblib_for_big_data.html.

Parameters:
  • filepath (str) – path to a pkl file.
  • backend (str) – backend to use, must be one of [‘pickle’, ‘joblib’].
  • load_args (Optional[Dict[str, Any]]) – Options for loading pickle files. Refer to the help file of pickle.load or joblib.load for options.
  • save_args (Optional[Dict[str, Any]]) – Options for saving pickle files. Refer to the help file of pickle.dump or joblib.dump for options.
  • version (Optional[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.
Raises:
  • ValueError – If ‘backend’ is not one of [‘pickle’, ‘joblib’].
  • ImportError – If ‘backend’ could not be imported.
Return type:

None

exists()

Checks whether a data set’s output already exists by calling the provided _exists() method.

Return type:bool
Returns:Flag indicating whether the output already exists.
Raises:DataSetError – when underlying exists method raises error.
classmethod from_config(name, config, load_version=None, save_version=None)

Create a data set instance using the configuration provided.

Parameters:
  • name (str) – Data set name.
  • config (Dict[str, Any]) – Data set config dictionary.
  • load_version (Optional[str]) – Version string to be used for load operation if the data set is versioned. Has no effect on the data set if versioning was not enabled.
  • save_version (Optional[str]) – Version string to be used for save operation if the data set is versioned. Has no effect on the data set if versioning was not enabled.
Return type:

AbstractDataSet

Returns:

An instance of an AbstractDataSet subclass.

Raises:

DataSetError – When the function fails to create the data set from its config.

get_last_load_version()

Versioned datasets should override this property to return last loaded version

Return type:Optional[str]
get_last_save_version()

Versioned datasets should override this property to return last saved version.

Return type:Optional[str]
load()

Loads data by delegation to the provided load method.

Return type:Any
Returns:Data returned by the provided load method.
Raises:DataSetError – When underlying load method raises error.
release()

Release any cached data.

Raises:DataSetError – when underlying exists method raises error.
Return type:None
save(data)

Saves data by delegation to the provided save method.

Parameters:data (Any) – the value to be saved by provided save method.
Raises:DataSetError – when underlying save method raises error.
Return type:None