Source code for pyspark.ml.evaluation
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# 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
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# http://www.apache.org/licenses/LICENSE-2.0
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from abc import abstractmethod, ABCMeta
from pyspark.ml.wrapper import JavaWrapper
from pyspark.ml.param import Param, Params
from pyspark.ml.param.shared import HasLabelCol, HasPredictionCol, HasRawPredictionCol
from pyspark.ml.util import keyword_only
from pyspark.mllib.common import inherit_doc
__all__ = ['Evaluator', 'BinaryClassificationEvaluator', 'RegressionEvaluator']
@inherit_doc
[docs]class Evaluator(Params):
"""
Base class for evaluators that compute metrics from predictions.
"""
__metaclass__ = ABCMeta
@abstractmethod
def _evaluate(self, dataset):
"""
Evaluates the output.
:param dataset: a dataset that contains labels/observations and
predictions
:return: metric
"""
raise NotImplementedError()
[docs] def evaluate(self, dataset, params={}):
"""
Evaluates the output with optional parameters.
:param dataset: a dataset that contains labels/observations and
predictions
:param params: an optional param map that overrides embedded
params
:return: metric
"""
if isinstance(params, dict):
if params:
return self.copy(params)._evaluate(dataset)
else:
return self._evaluate(dataset)
else:
raise ValueError("Params must be a param map but got %s." % type(params))
@inherit_doc
class JavaEvaluator(Evaluator, JavaWrapper):
"""
Base class for :py:class:`Evaluator`s that wrap Java/Scala
implementations.
"""
__metaclass__ = ABCMeta
def _evaluate(self, dataset):
"""
Evaluates the output.
:param dataset: a dataset that contains labels/observations and predictions.
:return: evaluation metric
"""
self._transfer_params_to_java()
return self._java_obj.evaluate(dataset._jdf)
@inherit_doc
[docs]class BinaryClassificationEvaluator(JavaEvaluator, HasLabelCol, HasRawPredictionCol):
"""
Evaluator for binary classification, which expects two input
columns: rawPrediction and label.
>>> from pyspark.mllib.linalg import Vectors
>>> scoreAndLabels = map(lambda x: (Vectors.dense([1.0 - x[0], x[0]]), x[1]),
... [(0.1, 0.0), (0.1, 1.0), (0.4, 0.0), (0.6, 0.0), (0.6, 1.0), (0.6, 1.0), (0.8, 1.0)])
>>> dataset = sqlContext.createDataFrame(scoreAndLabels, ["raw", "label"])
...
>>> evaluator = BinaryClassificationEvaluator(rawPredictionCol="raw")
>>> evaluator.evaluate(dataset)
0.70...
>>> evaluator.evaluate(dataset, {evaluator.metricName: "areaUnderPR"})
0.83...
"""
# a placeholder to make it appear in the generated doc
metricName = Param(Params._dummy(), "metricName",
"metric name in evaluation (areaUnderROC|areaUnderPR)")
@keyword_only
def __init__(self, rawPredictionCol="rawPrediction", labelCol="label",
metricName="areaUnderROC"):
"""
__init__(self, rawPredictionCol="rawPrediction", labelCol="label", \
metricName="areaUnderROC")
"""
super(BinaryClassificationEvaluator, self).__init__()
self._java_obj = self._new_java_obj(
"org.apache.spark.ml.evaluation.BinaryClassificationEvaluator", self.uid)
#: param for metric name in evaluation (areaUnderROC|areaUnderPR)
self.metricName = Param(self, "metricName",
"metric name in evaluation (areaUnderROC|areaUnderPR)")
self._setDefault(rawPredictionCol="rawPrediction", labelCol="label",
metricName="areaUnderROC")
kwargs = self.__init__._input_kwargs
self._set(**kwargs)
[docs] def setMetricName(self, value):
"""
Sets the value of :py:attr:`metricName`.
"""
self._paramMap[self.metricName] = value
return self
[docs] def getMetricName(self):
"""
Gets the value of metricName or its default value.
"""
return self.getOrDefault(self.metricName)
@keyword_only
[docs] def setParams(self, rawPredictionCol="rawPrediction", labelCol="label",
metricName="areaUnderROC"):
"""
setParams(self, rawPredictionCol="rawPrediction", labelCol="label", \
metricName="areaUnderROC")
Sets params for binary classification evaluator.
"""
kwargs = self.setParams._input_kwargs
return self._set(**kwargs)
@inherit_doc
[docs]class RegressionEvaluator(JavaEvaluator, HasLabelCol, HasPredictionCol):
"""
Evaluator for Regression, which expects two input
columns: prediction and label.
>>> scoreAndLabels = [(-28.98343821, -27.0), (20.21491975, 21.5),
... (-25.98418959, -22.0), (30.69731842, 33.0), (74.69283752, 71.0)]
>>> dataset = sqlContext.createDataFrame(scoreAndLabels, ["raw", "label"])
...
>>> evaluator = RegressionEvaluator(predictionCol="raw")
>>> evaluator.evaluate(dataset)
-2.842...
>>> evaluator.evaluate(dataset, {evaluator.metricName: "r2"})
0.993...
>>> evaluator.evaluate(dataset, {evaluator.metricName: "mae"})
-2.649...
"""
# Because we will maximize evaluation value (ref: `CrossValidator`),
# when we evaluate a metric that is needed to minimize (e.g., `"rmse"`, `"mse"`, `"mae"`),
# we take and output the negative of this metric.
metricName = Param(Params._dummy(), "metricName",
"metric name in evaluation (mse|rmse|r2|mae)")
@keyword_only
def __init__(self, predictionCol="prediction", labelCol="label",
metricName="rmse"):
"""
__init__(self, predictionCol="prediction", labelCol="label", \
metricName="rmse")
"""
super(RegressionEvaluator, self).__init__()
self._java_obj = self._new_java_obj(
"org.apache.spark.ml.evaluation.RegressionEvaluator", self.uid)
#: param for metric name in evaluation (mse|rmse|r2|mae)
self.metricName = Param(self, "metricName",
"metric name in evaluation (mse|rmse|r2|mae)")
self._setDefault(predictionCol="prediction", labelCol="label",
metricName="rmse")
kwargs = self.__init__._input_kwargs
self._set(**kwargs)
[docs] def setMetricName(self, value):
"""
Sets the value of :py:attr:`metricName`.
"""
self._paramMap[self.metricName] = value
return self
[docs] def getMetricName(self):
"""
Gets the value of metricName or its default value.
"""
return self.getOrDefault(self.metricName)
@keyword_only
[docs] def setParams(self, predictionCol="prediction", labelCol="label",
metricName="rmse"):
"""
setParams(self, predictionCol="prediction", labelCol="label", \
metricName="rmse")
Sets params for regression evaluator.
"""
kwargs = self.setParams._input_kwargs
return self._set(**kwargs)
if __name__ == "__main__":
import doctest
from pyspark.context import SparkContext
from pyspark.sql import SQLContext
globs = globals().copy()
# The small batch size here ensures that we see multiple batches,
# even in these small test examples:
sc = SparkContext("local[2]", "ml.evaluation tests")
sqlContext = SQLContext(sc)
globs['sc'] = sc
globs['sqlContext'] = sqlContext
(failure_count, test_count) = doctest.testmod(
globs=globs, optionflags=doctest.ELLIPSIS)
sc.stop()
if failure_count:
exit(-1)
