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# 

# Licensed to the Apache Software Foundation (ASF) under one or more 

# contributor license agreements. See the NOTICE file distributed with 

# this work for additional information regarding copyright ownership. 

# The ASF licenses this file to You under the Apache License, Version 2.0 

# (the "License"); you may not use this file except in compliance with 

# the License. You may obtain a copy of the License at 

# 

# http://www.apache.org/licenses/LICENSE-2.0 

# 

# Unless required by applicable law or agreed to in writing, software 

# distributed under the License is distributed on an "AS IS" BASIS, 

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 

# See the License for the specific language governing permissions and 

# limitations under the License. 

# 

 

from abc import ABCMeta, abstractmethod, abstractproperty 

 

import copy 

import threading 

 

from pyspark import since 

from pyspark.ml.common import inherit_doc 

from pyspark.ml.param.shared import HasInputCol, HasOutputCol, HasLabelCol, HasFeaturesCol, \ 

HasPredictionCol, Params 

from pyspark.sql.functions import udf 

from pyspark.sql.types import StructField, StructType 

 

 

class _FitMultipleIterator(object): 

""" 

Used by default implementation of Estimator.fitMultiple to produce models in a thread safe 

iterator. This class handles the simple case of fitMultiple where each param map should be 

fit independently. 

 

Parameters 

---------- 

fitSingleModel : function 

Callable[[int], Transformer] which fits an estimator to a dataset. 

`fitSingleModel` may be called up to `numModels` times, with a unique index each time. 

Each call to `fitSingleModel` with an index should return the Model associated with 

that index. 

numModel : int 

Number of models this iterator should produce. 

 

Notes 

----- 

See :py:meth:`Estimator.fitMultiple` for more info. 

""" 

def __init__(self, fitSingleModel, numModels): 

""" 

 

""" 

self.fitSingleModel = fitSingleModel 

self.numModel = numModels 

self.counter = 0 

self.lock = threading.Lock() 

 

def __iter__(self): 

return self 

 

def __next__(self): 

with self.lock: 

index = self.counter 

if index >= self.numModel: 

raise StopIteration("No models remaining.") 

self.counter += 1 

return index, self.fitSingleModel(index) 

 

def next(self): 

"""For python2 compatibility.""" 

return self.__next__() 

 

 

@inherit_doc 

class Estimator(Params, metaclass=ABCMeta): 

""" 

Abstract class for estimators that fit models to data. 

 

.. versionadded:: 1.3.0 

""" 

pass 

 

@abstractmethod 

def _fit(self, dataset): 

""" 

Fits a model to the input dataset. This is called by the default implementation of fit. 

 

 

Parameters 

---------- 

dataset : :py:class:`pyspark.sql.DataFrame` 

input dataset 

 

Returns 

------- 

:class:`Transformer` 

fitted model 

""" 

raise NotImplementedError() 

 

def fitMultiple(self, dataset, paramMaps): 

""" 

Fits a model to the input dataset for each param map in `paramMaps`. 

 

.. versionadded:: 2.3.0 

 

Parameters 

---------- 

dataset : :py:class:`pyspark.sql.DataFrame` 

input dataset. 

paramMaps : :py:class:`collections.abc.Sequence` 

A Sequence of param maps. 

 

Returns 

------- 

:py:class:`_FitMultipleIterator` 

A thread safe iterable which contains one model for each param map. Each 

call to `next(modelIterator)` will return `(index, model)` where model was fit 

using `paramMaps[index]`. `index` values may not be sequential. 

""" 

estimator = self.copy() 

 

def fitSingleModel(index): 

return estimator.fit(dataset, paramMaps[index]) 

 

return _FitMultipleIterator(fitSingleModel, len(paramMaps)) 

 

def fit(self, dataset, params=None): 

""" 

Fits a model to the input dataset with optional parameters. 

 

.. versionadded:: 1.3.0 

 

Parameters 

---------- 

dataset : :py:class:`pyspark.sql.DataFrame` 

input dataset. 

params : dict or list or tuple, optional 

an optional param map that overrides embedded params. If a list/tuple of 

param maps is given, this calls fit on each param map and returns a list of 

models. 

 

Returns 

------- 

:py:class:`Transformer` or a list of :py:class:`Transformer` 

fitted model(s) 

""" 

if params is None: 

params = dict() 

152 ↛ 153line 152 didn't jump to line 153, because the condition on line 152 was never true if isinstance(params, (list, tuple)): 

models = [None] * len(params) 

for index, model in self.fitMultiple(dataset, params): 

models[index] = model 

return models 

elif isinstance(params, dict): 

if params: 

return self.copy(params)._fit(dataset) 

else: 

return self._fit(dataset) 

else: 

raise TypeError("Params must be either a param map or a list/tuple of param maps, " 

"but got %s." % type(params)) 

 

 

@inherit_doc 

class Transformer(Params, metaclass=ABCMeta): 

""" 

Abstract class for transformers that transform one dataset into another. 

 

.. versionadded:: 1.3.0 

""" 

pass 

 

@abstractmethod 

def _transform(self, dataset): 

""" 

Transforms the input dataset. 

 

Parameters 

---------- 

dataset : :py:class:`pyspark.sql.DataFrame` 

input dataset. 

 

Returns 

------- 

:py:class:`pyspark.sql.DataFrame` 

transformed dataset 

""" 

raise NotImplementedError() 

 

def transform(self, dataset, params=None): 

""" 

Transforms the input dataset with optional parameters. 

 

.. versionadded:: 1.3.0 

 

Parameters 

---------- 

dataset : :py:class:`pyspark.sql.DataFrame` 

input dataset 

params : dict, optional 

an optional param map that overrides embedded params. 

 

Returns 

------- 

:py:class:`pyspark.sql.DataFrame` 

transformed dataset 

""" 

if params is None: 

params = dict() 

if isinstance(params, dict): 

if params: 

return self.copy(params)._transform(dataset) 

else: 

return self._transform(dataset) 

else: 

raise TypeError("Params must be a param map but got %s." % type(params)) 

 

 

@inherit_doc 

class Model(Transformer, metaclass=ABCMeta): 

""" 

Abstract class for models that are fitted by estimators. 

 

.. versionadded:: 1.4.0 

""" 

pass 

 

 

@inherit_doc 

class UnaryTransformer(HasInputCol, HasOutputCol, Transformer): 

""" 

Abstract class for transformers that take one input column, apply transformation, 

and output the result as a new column. 

 

.. versionadded:: 2.3.0 

""" 

 

def setInputCol(self, value): 

""" 

Sets the value of :py:attr:`inputCol`. 

""" 

return self._set(inputCol=value) 

 

def setOutputCol(self, value): 

""" 

Sets the value of :py:attr:`outputCol`. 

""" 

return self._set(outputCol=value) 

 

@abstractmethod 

def createTransformFunc(self): 

""" 

Creates the transform function using the given param map. The input param map already takes 

account of the embedded param map. So the param values should be determined 

solely by the input param map. 

""" 

raise NotImplementedError() 

 

@abstractmethod 

def outputDataType(self): 

""" 

Returns the data type of the output column. 

""" 

raise NotImplementedError() 

 

@abstractmethod 

def validateInputType(self, inputType): 

""" 

Validates the input type. Throw an exception if it is invalid. 

""" 

raise NotImplementedError() 

 

def transformSchema(self, schema): 

inputType = schema[self.getInputCol()].dataType 

self.validateInputType(inputType) 

279 ↛ 280line 279 didn't jump to line 280, because the condition on line 279 was never true if self.getOutputCol() in schema.names: 

raise ValueError("Output column %s already exists." % self.getOutputCol()) 

outputFields = copy.copy(schema.fields) 

outputFields.append(StructField(self.getOutputCol(), 

self.outputDataType(), 

nullable=False)) 

return StructType(outputFields) 

 

def _transform(self, dataset): 

self.transformSchema(dataset.schema) 

transformUDF = udf(self.createTransformFunc(), self.outputDataType()) 

transformedDataset = dataset.withColumn(self.getOutputCol(), 

transformUDF(dataset[self.getInputCol()])) 

return transformedDataset 

 

 

@inherit_doc 

class _PredictorParams(HasLabelCol, HasFeaturesCol, HasPredictionCol): 

""" 

Params for :py:class:`Predictor` and :py:class:`PredictorModel`. 

 

.. versionadded:: 3.0.0 

""" 

pass 

 

 

@inherit_doc 

class Predictor(Estimator, _PredictorParams, metaclass=ABCMeta): 

""" 

Estimator for prediction tasks (regression and classification). 

""" 

 

@since("3.0.0") 

def setLabelCol(self, value): 

""" 

Sets the value of :py:attr:`labelCol`. 

""" 

return self._set(labelCol=value) 

 

@since("3.0.0") 

def setFeaturesCol(self, value): 

""" 

Sets the value of :py:attr:`featuresCol`. 

""" 

return self._set(featuresCol=value) 

 

@since("3.0.0") 

def setPredictionCol(self, value): 

""" 

Sets the value of :py:attr:`predictionCol`. 

""" 

return self._set(predictionCol=value) 

 

 

@inherit_doc 

class PredictionModel(Model, _PredictorParams, metaclass=ABCMeta): 

""" 

Model for prediction tasks (regression and classification). 

""" 

 

@since("3.0.0") 

def setFeaturesCol(self, value): 

""" 

Sets the value of :py:attr:`featuresCol`. 

""" 

return self._set(featuresCol=value) 

 

@since("3.0.0") 

def setPredictionCol(self, value): 

""" 

Sets the value of :py:attr:`predictionCol`. 

""" 

return self._set(predictionCol=value) 

 

@abstractproperty 

@since("2.1.0") 

def numFeatures(self): 

""" 

Returns the number of features the model was trained on. If unknown, returns -1 

""" 

raise NotImplementedError() 

 

@abstractmethod 

@since("3.0.0") 

def predict(self, value): 

""" 

Predict label for the given features. 

""" 

raise NotImplementedError()