BucketedRandomProjectionLSH¶
-
class
pyspark.ml.feature.
BucketedRandomProjectionLSH
(inputCol=None, outputCol=None, seed=None, numHashTables=1, bucketLength=None)[source]¶ LSH class for Euclidean distance metrics. The input is dense or sparse vectors, each of which represents a point in the Euclidean distance space. The output will be vectors of configurable dimension. Hash values in the same dimension are calculated by the same hash function.
See also
>>> from pyspark.ml.linalg import Vectors >>> from pyspark.sql.functions import col >>> data = [(0, Vectors.dense([-1.0, -1.0 ]),), ... (1, Vectors.dense([-1.0, 1.0 ]),), ... (2, Vectors.dense([1.0, -1.0 ]),), ... (3, Vectors.dense([1.0, 1.0]),)] >>> df = spark.createDataFrame(data, ["id", "features"]) >>> brp = BucketedRandomProjectionLSH() >>> brp.setInputCol("features") BucketedRandomProjectionLSH... >>> brp.setOutputCol("hashes") BucketedRandomProjectionLSH... >>> brp.setSeed(12345) BucketedRandomProjectionLSH... >>> brp.setBucketLength(1.0) BucketedRandomProjectionLSH... >>> model = brp.fit(df) >>> model.getBucketLength() 1.0 >>> model.setOutputCol("hashes") BucketedRandomProjectionLSHModel... >>> model.transform(df).head() Row(id=0, features=DenseVector([-1.0, -1.0]), hashes=[DenseVector([-1.0])]) >>> data2 = [(4, Vectors.dense([2.0, 2.0 ]),), ... (5, Vectors.dense([2.0, 3.0 ]),), ... (6, Vectors.dense([3.0, 2.0 ]),), ... (7, Vectors.dense([3.0, 3.0]),)] >>> df2 = spark.createDataFrame(data2, ["id", "features"]) >>> model.approxNearestNeighbors(df2, Vectors.dense([1.0, 2.0]), 1).collect() [Row(id=4, features=DenseVector([2.0, 2.0]), hashes=[DenseVector([1.0])], distCol=1.0)] >>> model.approxSimilarityJoin(df, df2, 3.0, distCol="EuclideanDistance").select( ... col("datasetA.id").alias("idA"), ... col("datasetB.id").alias("idB"), ... col("EuclideanDistance")).show() +---+---+-----------------+ |idA|idB|EuclideanDistance| +---+---+-----------------+ | 3| 6| 2.23606797749979| +---+---+-----------------+ ... >>> model.approxSimilarityJoin(df, df2, 3, distCol="EuclideanDistance").select( ... col("datasetA.id").alias("idA"), ... col("datasetB.id").alias("idB"), ... col("EuclideanDistance")).show() +---+---+-----------------+ |idA|idB|EuclideanDistance| +---+---+-----------------+ | 3| 6| 2.23606797749979| +---+---+-----------------+ ... >>> brpPath = temp_path + "/brp" >>> brp.save(brpPath) >>> brp2 = BucketedRandomProjectionLSH.load(brpPath) >>> brp2.getBucketLength() == brp.getBucketLength() True >>> modelPath = temp_path + "/brp-model" >>> model.save(modelPath) >>> model2 = BucketedRandomProjectionLSHModel.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.
-
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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getBucketLength
()¶ Gets the value of bucketLength or its default value.
New in version 2.2.0.
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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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setBucketLength
(value)[source]¶ Sets the value of
bucketLength
.New in version 2.2.0.
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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, bucketLength=None)[source]¶ Sets params for this BucketedRandomProjectionLSH.
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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bucketLength
= Param(parent='undefined', name='bucketLength', doc='the length of each hash bucket, a larger bucket lowers the false negative rate.')¶
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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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