OneHotEncoder¶
-
class
pyspark.ml.feature.
OneHotEncoder
(inputCols=None, outputCols=None, handleInvalid='error', dropLast=True, inputCol=None, outputCol=None)[source]¶ A one-hot encoder that maps a column of category indices to a column of binary vectors, with at most a single one-value per row that indicates the input category index. For example with 5 categories, an input value of 2.0 would map to an output vector of [0.0, 0.0, 1.0, 0.0]. The last category is not included by default (configurable via
dropLast
), because it makes the vector entries sum up to one, and hence linearly dependent. So an input value of 4.0 maps to [0.0, 0.0, 0.0, 0.0].Note
This is different from scikit-learn’s OneHotEncoder, which keeps all categories. The output vectors are sparse.
When
handleInvalid
is configured to ‘keep’, an extra “category” indicating invalid values is added as last category. So whendropLast
is true, invalid values are encoded as all-zeros vector.Note
When encoding multi-column by using
inputCols
andoutputCols
params, input/output cols come in pairs, specified by the order in the arrays, and each pair is treated independently.See also
StringIndexer
for converting categorical values into category indices>>> from pyspark.ml.linalg import Vectors >>> df = spark.createDataFrame([(0.0,), (1.0,), (2.0,)], ["input"]) >>> ohe = OneHotEncoder() >>> ohe.setInputCols(["input"]) OneHotEncoder... >>> ohe.setOutputCols(["output"]) OneHotEncoder... >>> model = ohe.fit(df) >>> model.setOutputCols(["output"]) OneHotEncoderModel... >>> model.getHandleInvalid() 'error' >>> model.transform(df).head().output SparseVector(2, {0: 1.0}) >>> single_col_ohe = OneHotEncoder(inputCol="input", outputCol="output") >>> single_col_model = single_col_ohe.fit(df) >>> single_col_model.transform(df).head().output SparseVector(2, {0: 1.0}) >>> ohePath = temp_path + "/ohe" >>> ohe.save(ohePath) >>> loadedOHE = OneHotEncoder.load(ohePath) >>> loadedOHE.getInputCols() == ohe.getInputCols() True >>> modelPath = temp_path + "/ohe-model" >>> model.save(modelPath) >>> loadedModel = OneHotEncoderModel.load(modelPath) >>> loadedModel.categorySizes == model.categorySizes True
New in version 2.3.0.
Methods
Attributes
Methods Documentation
-
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
-
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.
-
getDropLast
()¶ Gets the value of dropLast or its default value.
New in version 2.3.0.
-
getHandleInvalid
()¶ Gets the value of handleInvalid or its default value.
-
getInputCol
()¶ Gets the value of inputCol or its default value.
-
getInputCols
()¶ Gets the value of inputCols or its default value.
-
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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getOutputCol
()¶ Gets the value of outputCol or its default value.
-
getOutputCols
()¶ Gets the value of outputCols 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.
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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).
-
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.
-
setHandleInvalid
(value)[source]¶ Sets the value of
handleInvalid
.New in version 3.0.0.
-
setOutputCols
(value)[source]¶ Sets the value of
outputCols
.New in version 3.0.0.
-
setParams
(self, inputCols=None, outputCols=None, handleInvalid='error', dropLast=True, inputCol=None, outputCol=None)[source]¶ Sets params for this OneHotEncoder.
New in version 2.3.0.
-
write
()¶ Returns an MLWriter instance for this ML instance.
Attributes Documentation
-
dropLast
= Param(parent='undefined', name='dropLast', doc='whether to drop the last category')¶
-
handleInvalid
= Param(parent='undefined', name='handleInvalid', doc="How to handle invalid data during transform(). Options are 'keep' (invalid data presented as an extra categorical feature) or error (throw an error). Note that this Param is only used during transform; during fitting, invalid data will result in an error.")¶
-
inputCol
= Param(parent='undefined', name='inputCol', doc='input column name.')¶
-
inputCols
= Param(parent='undefined', name='inputCols', doc='input column names.')¶
-
outputCol
= Param(parent='undefined', name='outputCol', doc='output column name.')¶
-
outputCols
= Param(parent='undefined', name='outputCols', doc='output column names.')¶
-
params
¶ Returns all params ordered by name. The default implementation uses
dir()
to get all attributes of typeParam
.
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