Source code for pyspark.ml.pipeline

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import os

from pyspark import keyword_only, since, SparkContext
from pyspark.ml.base import Estimator, Model, Transformer
from pyspark.ml.param import Param, Params
from pyspark.ml.util import MLReadable, MLWritable, JavaMLWriter, JavaMLReader, \
    DefaultParamsReader, DefaultParamsWriter, MLWriter, MLReader, JavaMLWritable
from pyspark.ml.wrapper import JavaParams
from pyspark.ml.common import inherit_doc


[docs]@inherit_doc class Pipeline(Estimator, MLReadable, MLWritable): """ A simple pipeline, which acts as an estimator. A Pipeline consists of a sequence of stages, each of which is either an :py:class:`Estimator` or a :py:class:`Transformer`. When :py:meth:`Pipeline.fit` is called, the stages are executed in order. If a stage is an :py:class:`Estimator`, its :py:meth:`Estimator.fit` method will be called on the input dataset to fit a model. Then the model, which is a transformer, will be used to transform the dataset as the input to the next stage. If a stage is a :py:class:`Transformer`, its :py:meth:`Transformer.transform` method will be called to produce the dataset for the next stage. The fitted model from a :py:class:`Pipeline` is a :py:class:`PipelineModel`, which consists of fitted models and transformers, corresponding to the pipeline stages. If stages is an empty list, the pipeline acts as an identity transformer. .. versionadded:: 1.3.0 """ stages = Param(Params._dummy(), "stages", "a list of pipeline stages") @keyword_only def __init__(self, *, stages=None): """ __init__(self, \\*, stages=None) """ super(Pipeline, self).__init__() kwargs = self._input_kwargs self.setParams(**kwargs)
[docs] def setStages(self, value): """ Set pipeline stages. .. versionadded:: 1.3.0 Parameters ---------- value : list of :py:class:`pyspark.ml.Transformer` or :py:class:`pyspark.ml.Estimator` Returns ------- :py:class:`Pipeline` the pipeline instance """ return self._set(stages=value)
[docs] @since("1.3.0") def getStages(self): """ Get pipeline stages. """ return self.getOrDefault(self.stages)
[docs] @keyword_only @since("1.3.0") def setParams(self, *, stages=None): """ setParams(self, \\*, stages=None) Sets params for Pipeline. """ kwargs = self._input_kwargs return self._set(**kwargs)
def _fit(self, dataset): stages = self.getStages() for stage in stages: if not (isinstance(stage, Estimator) or isinstance(stage, Transformer)): raise TypeError( "Cannot recognize a pipeline stage of type %s." % type(stage)) indexOfLastEstimator = -1 for i, stage in enumerate(stages): if isinstance(stage, Estimator): indexOfLastEstimator = i transformers = [] for i, stage in enumerate(stages): if i <= indexOfLastEstimator: if isinstance(stage, Transformer): transformers.append(stage) dataset = stage.transform(dataset) else: # must be an Estimator model = stage.fit(dataset) transformers.append(model) if i < indexOfLastEstimator: dataset = model.transform(dataset) else: transformers.append(stage) return PipelineModel(transformers)
[docs] def copy(self, extra=None): """ Creates a copy of this instance. .. versionadded:: 1.4.0 Parameters ---------- extra : dict, optional extra parameters Returns ------- :py:class:`Pipeline` new instance """ if extra is None: extra = dict() that = Params.copy(self, extra) stages = [stage.copy(extra) for stage in that.getStages()] return that.setStages(stages)
[docs] @since("2.0.0") def write(self): """Returns an MLWriter instance for this ML instance.""" allStagesAreJava = PipelineSharedReadWrite.checkStagesForJava(self.getStages()) if allStagesAreJava: return JavaMLWriter(self) return PipelineWriter(self)
[docs] @classmethod @since("2.0.0") def read(cls): """Returns an MLReader instance for this class.""" return PipelineReader(cls)
@classmethod def _from_java(cls, java_stage): """ Given a Java Pipeline, create and return a Python wrapper of it. Used for ML persistence. """ # Create a new instance of this stage. py_stage = cls() # Load information from java_stage to the instance. py_stages = [JavaParams._from_java(s) for s in java_stage.getStages()] py_stage.setStages(py_stages) py_stage._resetUid(java_stage.uid()) return py_stage def _to_java(self): """ Transfer this instance to a Java Pipeline. Used for ML persistence. Returns ------- py4j.java_gateway.JavaObject Java object equivalent to this instance. """ gateway = SparkContext._gateway cls = SparkContext._jvm.org.apache.spark.ml.PipelineStage java_stages = gateway.new_array(cls, len(self.getStages())) for idx, stage in enumerate(self.getStages()): java_stages[idx] = stage._to_java() _java_obj = JavaParams._new_java_obj("org.apache.spark.ml.Pipeline", self.uid) _java_obj.setStages(java_stages) return _java_obj
@inherit_doc class PipelineWriter(MLWriter): """ (Private) Specialization of :py:class:`MLWriter` for :py:class:`Pipeline` types """ def __init__(self, instance): super(PipelineWriter, self).__init__() self.instance = instance def saveImpl(self, path): stages = self.instance.getStages() PipelineSharedReadWrite.validateStages(stages) PipelineSharedReadWrite.saveImpl(self.instance, stages, self.sc, path) @inherit_doc class PipelineReader(MLReader): """ (Private) Specialization of :py:class:`MLReader` for :py:class:`Pipeline` types """ def __init__(self, cls): super(PipelineReader, self).__init__() self.cls = cls def load(self, path): metadata = DefaultParamsReader.loadMetadata(path, self.sc) if 'language' not in metadata['paramMap'] or metadata['paramMap']['language'] != 'Python': return JavaMLReader(self.cls).load(path) else: uid, stages = PipelineSharedReadWrite.load(metadata, self.sc, path) return Pipeline(stages=stages)._resetUid(uid) @inherit_doc class PipelineModelWriter(MLWriter): """ (Private) Specialization of :py:class:`MLWriter` for :py:class:`PipelineModel` types """ def __init__(self, instance): super(PipelineModelWriter, self).__init__() self.instance = instance def saveImpl(self, path): stages = self.instance.stages PipelineSharedReadWrite.validateStages(stages) PipelineSharedReadWrite.saveImpl(self.instance, stages, self.sc, path) @inherit_doc class PipelineModelReader(MLReader): """ (Private) Specialization of :py:class:`MLReader` for :py:class:`PipelineModel` types """ def __init__(self, cls): super(PipelineModelReader, self).__init__() self.cls = cls def load(self, path): metadata = DefaultParamsReader.loadMetadata(path, self.sc) if 'language' not in metadata['paramMap'] or metadata['paramMap']['language'] != 'Python': return JavaMLReader(self.cls).load(path) else: uid, stages = PipelineSharedReadWrite.load(metadata, self.sc, path) return PipelineModel(stages=stages)._resetUid(uid)
[docs]@inherit_doc class PipelineModel(Model, MLReadable, MLWritable): """ Represents a compiled pipeline with transformers and fitted models. .. versionadded:: 1.3.0 """ def __init__(self, stages): super(PipelineModel, self).__init__() self.stages = stages def _transform(self, dataset): for t in self.stages: dataset = t.transform(dataset) return dataset
[docs] def copy(self, extra=None): """ Creates a copy of this instance. .. versionadded:: 1.4.0 :param extra: extra parameters :returns: new instance """ if extra is None: extra = dict() stages = [stage.copy(extra) for stage in self.stages] return PipelineModel(stages)
[docs] @since("2.0.0") def write(self): """Returns an MLWriter instance for this ML instance.""" allStagesAreJava = PipelineSharedReadWrite.checkStagesForJava(self.stages) if allStagesAreJava: return JavaMLWriter(self) return PipelineModelWriter(self)
[docs] @classmethod @since("2.0.0") def read(cls): """Returns an MLReader instance for this class.""" return PipelineModelReader(cls)
@classmethod def _from_java(cls, java_stage): """ Given a Java PipelineModel, create and return a Python wrapper of it. Used for ML persistence. """ # Load information from java_stage to the instance. py_stages = [JavaParams._from_java(s) for s in java_stage.stages()] # Create a new instance of this stage. py_stage = cls(py_stages) py_stage._resetUid(java_stage.uid()) return py_stage def _to_java(self): """ Transfer this instance to a Java PipelineModel. Used for ML persistence. :return: Java object equivalent to this instance. """ gateway = SparkContext._gateway cls = SparkContext._jvm.org.apache.spark.ml.Transformer java_stages = gateway.new_array(cls, len(self.stages)) for idx, stage in enumerate(self.stages): java_stages[idx] = stage._to_java() _java_obj =\ JavaParams._new_java_obj("org.apache.spark.ml.PipelineModel", self.uid, java_stages) return _java_obj
@inherit_doc class PipelineSharedReadWrite(): """ Functions for :py:class:`MLReader` and :py:class:`MLWriter` shared between :py:class:`Pipeline` and :py:class:`PipelineModel` .. versionadded:: 2.3.0 """ @staticmethod def checkStagesForJava(stages): return all(isinstance(stage, JavaMLWritable) for stage in stages) @staticmethod def validateStages(stages): """ Check that all stages are Writable """ for stage in stages: if not isinstance(stage, MLWritable): raise ValueError("Pipeline write will fail on this pipeline " + "because stage %s of type %s is not MLWritable", stage.uid, type(stage)) @staticmethod def saveImpl(instance, stages, sc, path): """ Save metadata and stages for a :py:class:`Pipeline` or :py:class:`PipelineModel` - save metadata to path/metadata - save stages to stages/IDX_UID """ stageUids = [stage.uid for stage in stages] jsonParams = {'stageUids': stageUids, 'language': 'Python'} DefaultParamsWriter.saveMetadata(instance, path, sc, paramMap=jsonParams) stagesDir = os.path.join(path, "stages") for index, stage in enumerate(stages): stage.write().save(PipelineSharedReadWrite .getStagePath(stage.uid, index, len(stages), stagesDir)) @staticmethod def load(metadata, sc, path): """ Load metadata and stages for a :py:class:`Pipeline` or :py:class:`PipelineModel` Returns ------- tuple (UID, list of stages) """ stagesDir = os.path.join(path, "stages") stageUids = metadata['paramMap']['stageUids'] stages = [] for index, stageUid in enumerate(stageUids): stagePath = \ PipelineSharedReadWrite.getStagePath(stageUid, index, len(stageUids), stagesDir) stage = DefaultParamsReader.loadParamsInstance(stagePath, sc) stages.append(stage) return (metadata['uid'], stages) @staticmethod def getStagePath(stageUid, stageIdx, numStages, stagesDir): """ Get path for saving the given stage. """ stageIdxDigits = len(str(numStages)) stageDir = str(stageIdx).zfill(stageIdxDigits) + "_" + stageUid stagePath = os.path.join(stagesDir, stageDir) return stagePath