PCA¶
-
class
pyspark.ml.feature.
PCA
(k=None, inputCol=None, outputCol=None)[source]¶ PCA trains a model to project vectors to a lower dimensional space of the top
k
principal components.>>> from pyspark.ml.linalg import Vectors >>> data = [(Vectors.sparse(5, [(1, 1.0), (3, 7.0)]),), ... (Vectors.dense([2.0, 0.0, 3.0, 4.0, 5.0]),), ... (Vectors.dense([4.0, 0.0, 0.0, 6.0, 7.0]),)] >>> df = spark.createDataFrame(data,["features"]) >>> pca = PCA(k=2, inputCol="features") >>> pca.setOutputCol("pca_features") PCA... >>> model = pca.fit(df) >>> model.getK() 2 >>> model.setOutputCol("output") PCAModel... >>> model.transform(df).collect()[0].output DenseVector([1.648..., -4.013...]) >>> model.explainedVariance DenseVector([0.794..., 0.205...]) >>> pcaPath = temp_path + "/pca" >>> pca.save(pcaPath) >>> loadedPca = PCA.load(pcaPath) >>> loadedPca.getK() == pca.getK() True >>> modelPath = temp_path + "/pca-model" >>> model.save(modelPath) >>> loadedModel = PCAModel.load(modelPath) >>> loadedModel.pc == model.pc True >>> loadedModel.explainedVariance == model.explainedVariance True
New in version 1.5.0.
Methods
Attributes
Methods Documentation
-
clear
(param)¶ Clears a param from the param map if it has been explicitly set.
-
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
-
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=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
-
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.
-
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.
-
getInputCol
()¶ Gets the value of inputCol or its default value.
-
getK
()¶ Gets the value of k or its default value.
New in version 1.5.0.
-
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.
-
getOutputCol
()¶ Gets the value of outputCol or its default value.
-
getParam
(paramName)¶ Gets a param by its name.
-
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.
-
classmethod
load
(path)¶ Reads an ML instance from the input path, a shortcut of read().load(path).
-
classmethod
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.
-
setParams
(self, k=None, inputCol=None, outputCol=None)[source]¶ Set params for this PCA.
New in version 1.5.0.
-
write
()¶ Returns an MLWriter instance for this ML instance.
Attributes Documentation
-
inputCol
= Param(parent='undefined', name='inputCol', doc='input column name.')¶
-
k
= Param(parent='undefined', name='k', doc='the number of principal components')¶
-
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 typeParam
.
-