MinHashLSH¶
-
class
pyspark.ml.feature.
MinHashLSH
(inputCol=None, outputCol=None, seed=None, numHashTables=1)[source]¶ LSH class for Jaccard distance. The input can be dense or sparse vectors, but it is more efficient if it is sparse. For example, Vectors.sparse(10, [(2, 1.0), (3, 1.0), (5, 1.0)]) means there are 10 elements in the space. This set contains elements 2, 3, and 5. Also, any input vector must have at least 1 non-zero index, and all non-zero values are treated as binary “1” values.
See also
>>> from pyspark.ml.linalg import Vectors >>> from pyspark.sql.functions import col >>> data = [(0, Vectors.sparse(6, [0, 1, 2], [1.0, 1.0, 1.0]),), ... (1, Vectors.sparse(6, [2, 3, 4], [1.0, 1.0, 1.0]),), ... (2, Vectors.sparse(6, [0, 2, 4], [1.0, 1.0, 1.0]),)] >>> df = spark.createDataFrame(data, ["id", "features"]) >>> mh = MinHashLSH() >>> mh.setInputCol("features") MinHashLSH... >>> mh.setOutputCol("hashes") MinHashLSH... >>> mh.setSeed(12345) MinHashLSH... >>> model = mh.fit(df) >>> model.setInputCol("features") MinHashLSHModel... >>> model.transform(df).head() Row(id=0, features=SparseVector(6, {0: 1.0, 1: 1.0, 2: 1.0}), hashes=[DenseVector([6179668... >>> data2 = [(3, Vectors.sparse(6, [1, 3, 5], [1.0, 1.0, 1.0]),), ... (4, Vectors.sparse(6, [2, 3, 5], [1.0, 1.0, 1.0]),), ... (5, Vectors.sparse(6, [1, 2, 4], [1.0, 1.0, 1.0]),)] >>> df2 = spark.createDataFrame(data2, ["id", "features"]) >>> key = Vectors.sparse(6, [1, 2], [1.0, 1.0]) >>> model.approxNearestNeighbors(df2, key, 1).collect() [Row(id=5, features=SparseVector(6, {1: 1.0, 2: 1.0, 4: 1.0}), hashes=[DenseVector([6179668... >>> model.approxSimilarityJoin(df, df2, 0.6, distCol="JaccardDistance").select( ... col("datasetA.id").alias("idA"), ... col("datasetB.id").alias("idB"), ... col("JaccardDistance")).show() +---+---+---------------+ |idA|idB|JaccardDistance| +---+---+---------------+ | 0| 5| 0.5| | 1| 4| 0.5| +---+---+---------------+ ... >>> mhPath = temp_path + "/mh" >>> mh.save(mhPath) >>> mh2 = MinHashLSH.load(mhPath) >>> mh2.getOutputCol() == mh.getOutputCol() True >>> modelPath = temp_path + "/mh-model" >>> model.save(modelPath) >>> model2 = MinHashLSHModel.load(modelPath) >>> model.transform(df).head().hashes == model2.transform(df).head().hashes True
New in version 2.2.0.
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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getInputCol
()¶ Gets the value of inputCol or its default value.
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getNumHashTables
()¶ Gets the value of numHashTables or its default value.
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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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getOutputCol
()¶ Gets the value of outputCol or its default value.
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getParam
(paramName)¶ Gets a param by its name.
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getSeed
()¶ Gets the value of seed 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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setNumHashTables
(value)¶ Sets the value of
numHashTables
.
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setParams
(self, inputCol=None, outputCol=None, seed=None, numHashTables=1)[source]¶ Sets params for this MinHashLSH.
New in version 2.2.0.
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write
()¶ Returns an MLWriter instance for this ML instance.
Attributes Documentation
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inputCol
= Param(parent='undefined', name='inputCol', doc='input column name.')¶
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numHashTables
= Param(parent='undefined', name='numHashTables', doc='number of hash tables, where increasing number of hash tables lowers the false negative rate, and decreasing it improves the running performance.')¶
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outputCol
= Param(parent='undefined', name='outputCol', doc='output column name.')¶
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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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seed
= Param(parent='undefined', name='seed', doc='random seed.')¶
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