VarianceThresholdSelector¶

class pyspark.ml.feature.VarianceThresholdSelector(*, featuresCol: str = 'features', outputCol: Optional[str] = None, varianceThreshold: float = 0.0)¶

Feature selector that removes all low-variance features. Features with a variance not greater than the threshold will be removed. The default is to keep all features with non-zero variance, i.e. remove the features that have the same value in all samples.

Examples

>>> from pyspark.ml.linalg import Vectors
>>> df = spark.createDataFrame(
...    [(Vectors.dense([6.0, 7.0, 0.0, 7.0, 6.0, 0.0]),),
...     (Vectors.dense([0.0, 9.0, 6.0, 0.0, 5.0, 9.0]),),
...     (Vectors.dense([0.0, 9.0, 3.0, 0.0, 5.0, 5.0]),),
...     (Vectors.dense([0.0, 9.0, 8.0, 5.0, 6.0, 4.0]),),
...     (Vectors.dense([8.0, 9.0, 6.0, 5.0, 4.0, 4.0]),),
...     (Vectors.dense([8.0, 9.0, 6.0, 0.0, 0.0, 0.0]),)],
...    ["features"])
>>> selector = VarianceThresholdSelector(varianceThreshold=8.2, outputCol="selectedFeatures")
>>> model = selector.fit(df)
>>> model.getFeaturesCol()
'features'
>>> model.setFeaturesCol("features")
VarianceThresholdSelectorModel...
>>> model.transform(df).head().selectedFeatures
DenseVector([6.0, 7.0, 0.0])
>>> model.selectedFeatures
[0, 3, 5]
>>> varianceThresholdSelectorPath = temp_path + "/variance-threshold-selector"
>>> selector.save(varianceThresholdSelectorPath)
>>> loadedSelector = VarianceThresholdSelector.load(varianceThresholdSelectorPath)
>>> loadedSelector.getVarianceThreshold() == selector.getVarianceThreshold()
True
>>> modelPath = temp_path + "/variance-threshold-selector-model"
>>> model.save(modelPath)
>>> loadedModel = VarianceThresholdSelectorModel.load(modelPath)
>>> loadedModel.selectedFeatures == model.selectedFeatures
True
>>> loadedModel.transform(df).take(1) == model.transform(df).take(1)
True

Methods

`clear`(param)	Clears a param from the param map if it has been explicitly set.
`copy`([extra])	Creates a copy of this instance with the same uid and some extra params.
`explainParam`(param)	Explains a single param and returns its name, doc, and optional default value and user-supplied value in a string.
`explainParams`()	Returns the documentation of all params with their optionally default values and user-supplied values.
`extractParamMap`([extra])	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.
`fit`(dataset[, params])	Fits a model to the input dataset with optional parameters.
`fitMultiple`(dataset, paramMaps)	Fits a model to the input dataset for each param map in paramMaps.
`getFeaturesCol`()	Gets the value of featuresCol or its default value.
`getOrDefault`(param)	Gets the value of a param in the user-supplied param map or its default value.
`getOutputCol`()	Gets the value of outputCol or its default value.
`getParam`(paramName)	Gets a param by its name.
`getVarianceThreshold`()	Gets the value of varianceThreshold or its default value.
`hasDefault`(param)	Checks whether a param has a default value.
`hasParam`(paramName)	Tests whether this instance contains a param with a given (string) name.
`isDefined`(param)	Checks whether a param is explicitly set by user or has a default value.
`isSet`(param)	Checks whether a param is explicitly set by user.
`load`(path)	Reads an ML instance from the input path, a shortcut of read().load(path).
`read`()	Returns an MLReader instance for this class.
`save`(path)	Save this ML instance to the given path, a shortcut of ‘write().save(path)’.
`set`(param, value)	Sets a parameter in the embedded param map.
`setFeaturesCol`(value)	Sets the value of `featuresCol`.
`setOutputCol`(value)	Sets the value of `outputCol`.
`setParams`(self, \*[, featuresCol, …])	Sets params for this VarianceThresholdSelector.
`setVarianceThreshold`(value)	Sets the value of `varianceThreshold`.
`write`()	Returns an MLWriter instance for this ML instance.

Attributes

`featuresCol`
`outputCol`
`params`	Returns all params ordered by name.
`varianceThreshold`

Methods Documentation

clear(param: pyspark.ml.param.Param) → None¶: Clears a param from the param map if it has been explicitly set.

copy(extra: Optional[ParamMap] = None) → JP¶

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

extradict, optional: Extra parameters to copy to the new instance

Returns

JavaParams: Copy of this instance

explainParam(param: Union[str, pyspark.ml.param.Param]) → str¶: Explains a single param and returns its name, doc, and optional default value and user-supplied value in a string.

explainParams() → str¶: Returns the documentation of all params with their optionally default values and user-supplied values.

extractParamMap(extra: Optional[ParamMap] = None) → ParamMap¶

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

extradict, optional: extra param values

Returns

dict: merged param map

fit(dataset: pyspark.sql.dataframe.DataFrame, params: Union[ParamMap, List[ParamMap], Tuple[ParamMap], None] = None) → Union[M, List[M]]¶

Fits a model to the input dataset with optional parameters.

Parameters

datasetpyspark.sql.DataFrame: input dataset.
paramsdict 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

Transformer or a list of Transformer: fitted model(s)

fitMultiple(dataset: pyspark.sql.dataframe.DataFrame, paramMaps: Sequence[ParamMap]) → Iterator[Tuple[int, M]]¶

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

Parameters

datasetpyspark.sql.DataFrame: input dataset.
paramMapscollections.abc.Sequence: A Sequence of param maps.

Returns

_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.

getFeaturesCol() → str¶: Gets the value of featuresCol or its default value.

getOrDefault(param: Union[str, pyspark.ml.param.Param[T]]) → Union[Any, T]¶: Gets the value of a param in the user-supplied param map or its default value. Raises an error if neither is set.

getOutputCol() → str¶: Gets the value of outputCol or its default value.

getParam(paramName: str) → pyspark.ml.param.Param ¶: Gets a param by its name.

getVarianceThreshold() → float¶: Gets the value of varianceThreshold or its default value.

hasDefault(param: Union[str, pyspark.ml.param.Param[Any]]) → bool¶: Checks whether a param has a default value.

hasParam(paramName: str) → bool¶: Tests whether this instance contains a param with a given (string) name.

isDefined(param: Union[str, pyspark.ml.param.Param[Any]]) → bool¶: Checks whether a param is explicitly set by user or has a default value.

isSet(param: Union[str, pyspark.ml.param.Param[Any]]) → bool¶: Checks whether a param is explicitly set by user.

classmethod load(path: str) → RL¶: Reads an ML instance from the input path, a shortcut of read().load(path).

classmethod read() → pyspark.ml.util.JavaMLReader[RL]¶: Returns an MLReader instance for this class.

save(path: str) → None¶: Save this ML instance to the given path, a shortcut of ‘write().save(path)’.

set(param: pyspark.ml.param.Param, value: Any) → None¶: Sets a parameter in the embedded param map.

setFeaturesCol(value: str) → pyspark.ml.feature.VarianceThresholdSelector ¶: Sets the value of featuresCol.

setOutputCol(value: str) → pyspark.ml.feature.VarianceThresholdSelector ¶: Sets the value of outputCol.

setParams(self, \*, featuresCol="features", outputCol=None, varianceThreshold=0.0)¶: Sets params for this VarianceThresholdSelector.

setVarianceThreshold(value: float) → pyspark.ml.feature.VarianceThresholdSelector ¶: Sets the value of varianceThreshold.

write() → pyspark.ml.util.JavaMLWriter¶: Returns an MLWriter instance for this ML instance.

Attributes Documentation

featuresCol = Param(parent='undefined', name='featuresCol', doc='features column name.')¶

outputCol = Param(parent='undefined', name='outputCol', doc='output column name.')¶

params¶: Returns all params ordered by name. The default implementation uses dir() to get all attributes of type Param.

varianceThreshold = Param(parent='undefined', name='varianceThreshold', doc='Param for variance threshold. Features with a variance not greater than this threshold will be removed. The default value is 0.0.')¶

UnivariateFeatureSelectorModel

VarianceThresholdSelectorModel