Source code for mmlspark.core.schema.Utils

# Copyright (C) Microsoft Corporation. All rights reserved.
# Licensed under the MIT License. See LICENSE in project root for information.

import sys

if sys.version >= "3":
    basestring = str

from import JavaMLReadable, JavaMLReader, MLReadable
from import JavaParams
from import inherit_doc, _java2py
from pyspark import SparkContext

[docs]def from_java(java_stage, stage_name): """ Given a Java object, create and return a Python wrapper of it. Used for ML persistence. Meta-algorithms such as Pipeline should override this method as a classmethod. Args: java_stage (str): stage_name (str): Returns: object: The python wrapper """ def __get_class(clazz): """ Loads a python object from its class Args: clazz (str): The name of the class Returns: object: The python object """ parts = clazz.split(".") module = ".".join(parts[:-1]) m = __import__(module) for comp in parts[1:]: m = getattr(m, comp) return m # Generate a default new instance from the stage_name class. py_type = __get_class(stage_name) if issubclass(py_type, JavaParams): # Load information from java_stage to the instance. py_stage = py_type() py_stage._java_obj = java_stage py_stage._resetUid(java_stage.uid()) py_stage._transfer_params_from_java() elif hasattr(py_type, "_from_java"): py_stage = py_type._from_java(java_stage) else: raise NotImplementedError("This Java stage cannot be loaded into Python currently: %r" % stage_name) return py_stage
[docs]@inherit_doc class JavaMMLReadable(MLReadable): """ (Private) Mixin for instances that provide JavaMLReader. """
[docs] @classmethod def read(cls): """Returns an MLReader instance for this class.""" return JavaMMLReader(cls)
[docs]@inherit_doc class ComplexParamsMixin(MLReadable): def _transfer_params_from_java(self): """ Transforms the embedded from the companion Java object. """ sc = SparkContext._active_spark_context for param in self.params: if self._java_obj.hasParam( java_param = self._java_obj.getParam( # SPARK-14931: Only check set back to avoid default mismatch. complex_param_class = is_complex_param = complex_param_class.isAssignableFrom(java_param.getClass()) if self._java_obj.isSet(java_param): if is_complex_param: value = self._java_obj.getOrDefault(java_param) else: value = _java2py(sc, self._java_obj.getOrDefault(java_param)) self._set(**{ value})
[docs]@inherit_doc class JavaMMLReader(JavaMLReader): """ (Private) Specialization of :py:class:`MLReader` for :py:class:`JavaParams` types """ def __init__(self, clazz): super(JavaMMLReader, self).__init__(clazz) @classmethod def _java_loader_class(cls, clazz): """ Returns the full class name of the Java ML instance. """ return clazz.getJavaPackage()