NaiveBayes¶
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class
pyspark.ml.classification.
NaiveBayes
(featuresCol='features', labelCol='label', predictionCol='prediction', probabilityCol='probability', rawPredictionCol='rawPrediction', smoothing=1.0, modelType='multinomial', thresholds=None, weightCol=None)[source]¶ Naive Bayes Classifiers. It supports both Multinomial and Bernoulli NB. Multinomial NB can handle finitely supported discrete data. For example, by converting documents into TF-IDF vectors, it can be used for document classification. By making every vector a binary (0/1) data, it can also be used as Bernoulli NB. The input feature values for Multinomial NB and Bernoulli NB must be nonnegative. Since 3.0.0, it supports Complement NB which is an adaptation of the Multinomial NB. Specifically, Complement NB uses statistics from the complement of each class to compute the model’s coefficients. The inventors of Complement NB show empirically that the parameter estimates for CNB are more stable than those for Multinomial NB. Like Multinomial NB, the input feature values for Complement NB must be nonnegative. Since 3.0.0, it also supports Gaussian NB <https://en.wikipedia.org/wiki/Naive_Bayes_classifier#Gaussian_naive_Bayes>`_. which can handle continuous data.
>>> from pyspark.sql import Row >>> from pyspark.ml.linalg import Vectors >>> df = spark.createDataFrame([ ... Row(label=0.0, weight=0.1, features=Vectors.dense([0.0, 0.0])), ... Row(label=0.0, weight=0.5, features=Vectors.dense([0.0, 1.0])), ... Row(label=1.0, weight=1.0, features=Vectors.dense([1.0, 0.0]))]) >>> nb = NaiveBayes(smoothing=1.0, modelType="multinomial", weightCol="weight") >>> model = nb.fit(df) >>> model.setFeaturesCol("features") NaiveBayesModel... >>> model.getSmoothing() 1.0 >>> model.pi DenseVector([-0.81..., -0.58...]) >>> model.theta DenseMatrix(2, 2, [-0.91..., -0.51..., -0.40..., -1.09...], 1) >>> model.sigma DenseMatrix(0, 0, [...], ...) >>> test0 = sc.parallelize([Row(features=Vectors.dense([1.0, 0.0]))]).toDF() >>> model.predict(test0.head().features) 1.0 >>> model.predictRaw(test0.head().features) DenseVector([-1.72..., -0.99...]) >>> model.predictProbability(test0.head().features) DenseVector([0.32..., 0.67...]) >>> result = model.transform(test0).head() >>> result.prediction 1.0 >>> result.probability DenseVector([0.32..., 0.67...]) >>> result.rawPrediction DenseVector([-1.72..., -0.99...]) >>> test1 = sc.parallelize([Row(features=Vectors.sparse(2, [0], [1.0]))]).toDF() >>> model.transform(test1).head().prediction 1.0 >>> nb_path = temp_path + "/nb" >>> nb.save(nb_path) >>> nb2 = NaiveBayes.load(nb_path) >>> nb2.getSmoothing() 1.0 >>> model_path = temp_path + "/nb_model" >>> model.save(model_path) >>> model2 = NaiveBayesModel.load(model_path) >>> model.pi == model2.pi True >>> model.theta == model2.theta True >>> nb = nb.setThresholds([0.01, 10.00]) >>> model3 = nb.fit(df) >>> result = model3.transform(test0).head() >>> result.prediction 0.0 >>> nb3 = NaiveBayes().setModelType("gaussian") >>> model4 = nb3.fit(df) >>> model4.getModelType() 'gaussian' >>> model4.sigma DenseMatrix(2, 2, [0.0, 0.25, 0.0, 0.0], 1) >>> nb5 = NaiveBayes(smoothing=1.0, modelType="complement", weightCol="weight") >>> model5 = nb5.fit(df) >>> model5.getModelType() 'complement' >>> model5.theta DenseMatrix(2, 2, [...], 1) >>> model5.sigma DenseMatrix(0, 0, [...], ...)
New in version 1.5.0.
Methods
Attributes
Methods Documentation
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clear
(param)¶ Clears a param from the param map if it has been explicitly set.
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copy
(extra=None)¶ Creates a copy of this instance with the same uid and some extra params. This implementation first calls Params.copy and then make a copy of the companion Java pipeline component with extra params. So both the Python wrapper and the Java pipeline component get copied.
- Parameters
extra – Extra parameters to copy to the new instance
- Returns
Copy of this instance
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explainParam
(param)¶ Explains a single param and returns its name, doc, and optional default value and user-supplied value in a string.
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explainParams
()¶ Returns the documentation of all params with their optionally default values and user-supplied values.
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extractParamMap
(extra=None)¶ Extracts the embedded default param values and user-supplied values, and then merges them with extra values from input into a flat param map, where the latter value is used if there exist conflicts, i.e., with ordering: default param values < user-supplied values < extra.
- Parameters
extra – extra param values
- Returns
merged param map
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fit
(dataset, params=None)¶ Fits a model to the input dataset with optional parameters.
- Parameters
dataset – input dataset, which is an instance of
pyspark.sql.DataFrame
params – 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
fitted model(s)
New in version 1.3.0.
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fitMultiple
(dataset, paramMaps)¶ Fits a model to the input dataset for each param map in paramMaps.
- Parameters
dataset – input dataset, which is an instance of
pyspark.sql.DataFrame
.paramMaps – A Sequence of param maps.
- Returns
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.
New in version 2.3.0.
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getFeaturesCol
()¶ Gets the value of featuresCol or its default value.
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getLabelCol
()¶ Gets the value of labelCol or its default value.
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getModelType
()¶ Gets the value of modelType or its default value.
New in version 1.5.0.
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getOrDefault
(param)¶ Gets the value of a param in the user-supplied param map or its default value. Raises an error if neither is set.
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getParam
(paramName)¶ Gets a param by its name.
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getPredictionCol
()¶ Gets the value of predictionCol or its default value.
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getProbabilityCol
()¶ Gets the value of probabilityCol or its default value.
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getRawPredictionCol
()¶ Gets the value of rawPredictionCol or its default value.
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getSmoothing
()¶ Gets the value of smoothing or its default value.
New in version 1.5.0.
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getThresholds
()¶ Gets the value of thresholds or its default value.
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getWeightCol
()¶ Gets the value of weightCol or its default value.
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hasDefault
(param)¶ Checks whether a param has a default value.
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hasParam
(paramName)¶ Tests whether this instance contains a param with a given (string) name.
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isDefined
(param)¶ Checks whether a param is explicitly set by user or has a default value.
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isSet
(param)¶ Checks whether a param is explicitly set by user.
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classmethod
load
(path)¶ Reads an ML instance from the input path, a shortcut of read().load(path).
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classmethod
read
()¶ Returns an MLReader instance for this class.
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save
(path)¶ Save this ML instance to the given path, a shortcut of ‘write().save(path)’.
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set
(param, value)¶ Sets a parameter in the embedded param map.
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setFeaturesCol
(value)¶ Sets the value of
featuresCol
.New in version 3.0.0.
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setParams
(self, featuresCol='features', labelCol='label', predictionCol='prediction', probabilityCol='probability', rawPredictionCol='rawPrediction', smoothing=1.0, modelType='multinomial', thresholds=None, weightCol=None)[source]¶ Sets params for Naive Bayes.
New in version 1.5.0.
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setPredictionCol
(value)¶ Sets the value of
predictionCol
.New in version 3.0.0.
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setProbabilityCol
(value)¶ Sets the value of
probabilityCol
.New in version 3.0.0.
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setRawPredictionCol
(value)¶ Sets the value of
rawPredictionCol
.New in version 3.0.0.
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setThresholds
(value)¶ Sets the value of
thresholds
.New in version 3.0.0.
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write
()¶ Returns an MLWriter instance for this ML instance.
Attributes Documentation
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featuresCol
= Param(parent='undefined', name='featuresCol', doc='features column name.')¶
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labelCol
= Param(parent='undefined', name='labelCol', doc='label column name.')¶
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modelType
= Param(parent='undefined', name='modelType', doc='The model type which is a string (case-sensitive). Supported options: multinomial (default), bernoulli and gaussian.')¶
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params
¶ Returns all params ordered by name. The default implementation uses
dir()
to get all attributes of typeParam
.
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predictionCol
= Param(parent='undefined', name='predictionCol', doc='prediction column name.')¶
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probabilityCol
= Param(parent='undefined', name='probabilityCol', doc='Column name for predicted class conditional probabilities. Note: Not all models output well-calibrated probability estimates! These probabilities should be treated as confidences, not precise probabilities.')¶
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rawPredictionCol
= Param(parent='undefined', name='rawPredictionCol', doc='raw prediction (a.k.a. confidence) column name.')¶
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smoothing
= Param(parent='undefined', name='smoothing', doc='The smoothing parameter, should be >= 0, default is 1.0')¶
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thresholds
= Param(parent='undefined', name='thresholds', doc="Thresholds in multi-class classification to adjust the probability of predicting each class. Array must have length equal to the number of classes, with values > 0, excepting that at most one value may be 0. The class with largest value p/t is predicted, where p is the original probability of that class and t is the class's threshold.")¶
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weightCol
= Param(parent='undefined', name='weightCol', doc='weight column name. If this is not set or empty, we treat all instance weights as 1.0.')¶
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