spark-instrumented-optimizer/python/pyspark/ml/fpm.py

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from pyspark import keyword_only, since
from pyspark.sql import DataFrame
from pyspark.ml.util import *
from pyspark.ml.wrapper import JavaEstimator, JavaModel, JavaParams
from pyspark.ml.param.shared import *

__all__ = ["FPGrowth", "FPGrowthModel", "PrefixSpan"]


class HasMinSupport(Params):
    """
    Mixin for param minSupport.
    """

    minSupport = Param(
        Params._dummy(),
        "minSupport",
        "Minimal support level of the frequent pattern. [0.0, 1.0]. " +
        "Any pattern that appears more than (minSupport * size-of-the-dataset) " +
        "times will be output in the frequent itemsets.",
        typeConverter=TypeConverters.toFloat)

    def setMinSupport(self, value):
        """
        Sets the value of :py:attr:`minSupport`.
        """
        return self._set(minSupport=value)

    def getMinSupport(self):
        """
        Gets the value of minSupport or its default value.
        """
        return self.getOrDefault(self.minSupport)


class HasNumPartitions(Params):
    """
    Mixin for param numPartitions: Number of partitions (at least 1) used by parallel FP-growth.
    """

    numPartitions = Param(
        Params._dummy(),
        "numPartitions",
        "Number of partitions (at least 1) used by parallel FP-growth. " +
        "By default the param is not set, " +
        "and partition number of the input dataset is used.",
        typeConverter=TypeConverters.toInt)

    def setNumPartitions(self, value):
        """
        Sets the value of :py:attr:`numPartitions`.
        """
        return self._set(numPartitions=value)

    def getNumPartitions(self):
        """
        Gets the value of :py:attr:`numPartitions` or its default value.
        """
        return self.getOrDefault(self.numPartitions)


class HasMinConfidence(Params):
    """
    Mixin for param minConfidence.
    """

    minConfidence = Param(
        Params._dummy(),
        "minConfidence",
        "Minimal confidence for generating Association Rule. [0.0, 1.0]. " +
        "minConfidence will not affect the mining for frequent itemsets, " +
        "but will affect the association rules generation.",
        typeConverter=TypeConverters.toFloat)

    def setMinConfidence(self, value):
        """
        Sets the value of :py:attr:`minConfidence`.
        """
        return self._set(minConfidence=value)

    def getMinConfidence(self):
        """
        Gets the value of minConfidence or its default value.
        """
        return self.getOrDefault(self.minConfidence)


class HasItemsCol(Params):
    """
    Mixin for param itemsCol: items column name.
    """

    itemsCol = Param(Params._dummy(), "itemsCol",
                     "items column name", typeConverter=TypeConverters.toString)

    def setItemsCol(self, value):
        """
        Sets the value of :py:attr:`itemsCol`.
        """
        return self._set(itemsCol=value)

    def getItemsCol(self):
        """
        Gets the value of itemsCol or its default value.
        """
        return self.getOrDefault(self.itemsCol)


class FPGrowthModel(JavaModel, JavaMLWritable, JavaMLReadable):
    """
    Model fitted by FPGrowth.

    .. versionadded:: 2.2.0
    """
    @property
    @since("2.2.0")
    def freqItemsets(self):
        """
        DataFrame with two columns:
        * `items` - Itemset of the same type as the input column.
        * `freq`  - Frequency of the itemset (`LongType`).
        """
        return self._call_java("freqItemsets")

    @property
    @since("2.2.0")
    def associationRules(self):
        """
        DataFrame with four columns:
        * `antecedent`  - Array of the same type as the input column.
        * `consequent`  - Array of the same type as the input column.
        * `confidence`  - Confidence for the rule (`DoubleType`).
        * `lift`        - Lift for the rule (`DoubleType`).
        """
        return self._call_java("associationRules")


class FPGrowth(JavaEstimator, HasItemsCol, HasPredictionCol,
               HasMinSupport, HasNumPartitions, HasMinConfidence,
               JavaMLWritable, JavaMLReadable):

    r"""
    A parallel FP-growth algorithm to mine frequent itemsets. The algorithm is described in
    Li et al., PFP: Parallel FP-Growth for Query Recommendation [LI2008]_.
    PFP distributes computation in such a way that each worker executes an
    independent group of mining tasks. The FP-Growth algorithm is described in
    Han et al., Mining frequent patterns without candidate generation [HAN2000]_

    .. [LI2008] https://doi.org/10.1145/1454008.1454027
    .. [HAN2000] https://doi.org/10.1145/335191.335372

    .. note:: null values in the feature column are ignored during fit().
    .. note:: Internally `transform` `collects` and `broadcasts` association rules.

    >>> from pyspark.sql.functions import split
    >>> data = (spark.read
    ...     .text("data/mllib/sample_fpgrowth.txt")
    ...     .select(split("value", "\s+").alias("items")))
    >>> data.show(truncate=False)
    +------------------------+
    |items                   |
    +------------------------+
    |[r, z, h, k, p]         |
    |[z, y, x, w, v, u, t, s]|
    |[s, x, o, n, r]         |
    |[x, z, y, m, t, s, q, e]|
    |[z]                     |
    |[x, z, y, r, q, t, p]   |
    +------------------------+
    >>> fp = FPGrowth(minSupport=0.2, minConfidence=0.7)
    >>> fpm = fp.fit(data)
    >>> fpm.freqItemsets.show(5)
    +---------+----+
    |    items|freq|
    +---------+----+
    |      [s]|   3|
    |   [s, x]|   3|
    |[s, x, z]|   2|
    |   [s, z]|   2|
    |      [r]|   3|
    +---------+----+
    only showing top 5 rows
    >>> fpm.associationRules.show(5)
    +----------+----------+----------+
    |antecedent|consequent|confidence|
    +----------+----------+----------+
    |    [t, s]|       [y]|       1.0|
    |    [t, s]|       [x]|       1.0|
    |    [t, s]|       [z]|       1.0|
    |       [p]|       [r]|       1.0|
    |       [p]|       [z]|       1.0|
    +----------+----------+----------+
    only showing top 5 rows
    >>> new_data = spark.createDataFrame([(["t", "s"], )], ["items"])
    >>> sorted(fpm.transform(new_data).first().prediction)
    ['x', 'y', 'z']

    .. versionadded:: 2.2.0
    """
    @keyword_only
    def __init__(self, minSupport=0.3, minConfidence=0.8, itemsCol="items",
                 predictionCol="prediction", numPartitions=None):
        """
        __init__(self, minSupport=0.3, minConfidence=0.8, itemsCol="items", \
                 predictionCol="prediction", numPartitions=None)
        """
        super(FPGrowth, self).__init__()
        self._java_obj = self._new_java_obj("org.apache.spark.ml.fpm.FPGrowth", self.uid)
        self._setDefault(minSupport=0.3, minConfidence=0.8,
                         itemsCol="items", predictionCol="prediction")
        kwargs = self._input_kwargs
        self.setParams(**kwargs)

    @keyword_only
    @since("2.2.0")
    def setParams(self, minSupport=0.3, minConfidence=0.8, itemsCol="items",
                  predictionCol="prediction", numPartitions=None):
        """
        setParams(self, minSupport=0.3, minConfidence=0.8, itemsCol="items", \
                  predictionCol="prediction", numPartitions=None)
        """
        kwargs = self._input_kwargs
        return self._set(**kwargs)

    def _create_model(self, java_model):
        return FPGrowthModel(java_model)


class PrefixSpan(JavaParams):
    """
    A parallel PrefixSpan algorithm to mine frequent sequential patterns.
    The PrefixSpan algorithm is described in J. Pei, et al., PrefixSpan: Mining Sequential Patterns
    Efficiently by Prefix-Projected Pattern Growth
    (see <a href="https://doi.org/10.1109/ICDE.2001.914830">here</a>).
    This class is not yet an Estimator/Transformer, use :py:func:`findFrequentSequentialPatterns`
    method to run the PrefixSpan algorithm.

    @see <a href="https://en.wikipedia.org/wiki/Sequential_Pattern_Mining">Sequential Pattern Mining
    (Wikipedia)</a>
    .. versionadded:: 2.4.0

    """

    minSupport = Param(Params._dummy(), "minSupport", "The minimal support level of the " +
                       "sequential pattern. Sequential pattern that appears more than " +
                       "(minSupport * size-of-the-dataset) times will be output. Must be >= 0.",
                       typeConverter=TypeConverters.toFloat)

    maxPatternLength = Param(Params._dummy(), "maxPatternLength",
                             "The maximal length of the sequential pattern. Must be > 0.",
                             typeConverter=TypeConverters.toInt)

    maxLocalProjDBSize = Param(Params._dummy(), "maxLocalProjDBSize",
                               "The maximum number of items (including delimiters used in the " +
                               "internal storage format) allowed in a projected database before " +
                               "local processing. If a projected database exceeds this size, " +
                               "another iteration of distributed prefix growth is run. " +
                               "Must be > 0.",
                               typeConverter=TypeConverters.toInt)

    sequenceCol = Param(Params._dummy(), "sequenceCol", "The name of the sequence column in " +
                        "dataset, rows with nulls in this column are ignored.",
                        typeConverter=TypeConverters.toString)

    @keyword_only
    def __init__(self, minSupport=0.1, maxPatternLength=10, maxLocalProjDBSize=32000000,
                 sequenceCol="sequence"):
        """
        __init__(self, minSupport=0.1, maxPatternLength=10, maxLocalProjDBSize=32000000, \
                 sequenceCol="sequence")
        """
        super(PrefixSpan, self).__init__()
        self._java_obj = self._new_java_obj("org.apache.spark.ml.fpm.PrefixSpan", self.uid)
        self._setDefault(minSupport=0.1, maxPatternLength=10, maxLocalProjDBSize=32000000,
                         sequenceCol="sequence")
        kwargs = self._input_kwargs
        self.setParams(**kwargs)

    @keyword_only
    @since("2.4.0")
    def setParams(self, minSupport=0.1, maxPatternLength=10, maxLocalProjDBSize=32000000,
                  sequenceCol="sequence"):
        """
        setParams(self, minSupport=0.1, maxPatternLength=10, maxLocalProjDBSize=32000000, \
                  sequenceCol="sequence")
        """
        kwargs = self._input_kwargs
        return self._set(**kwargs)

    @since("2.4.0")
    def findFrequentSequentialPatterns(self, dataset):
        """
        Finds the complete set of frequent sequential patterns in the input sequences of itemsets.

        :param dataset: A dataframe containing a sequence column which is
                        `ArrayType(ArrayType(T))` type, T is the item type for the input dataset.
        :return: A `DataFrame` that contains columns of sequence and corresponding frequency.
                 The schema of it will be:
                 - `sequence: ArrayType(ArrayType(T))` (T is the item type)
                 - `freq: Long`

        >>> from pyspark.ml.fpm import PrefixSpan
        >>> from pyspark.sql import Row
        >>> df = sc.parallelize([Row(sequence=[[1, 2], [3]]),
        ...                      Row(sequence=[[1], [3, 2], [1, 2]]),
        ...                      Row(sequence=[[1, 2], [5]]),
        ...                      Row(sequence=[[6]])]).toDF()
        >>> prefixSpan = PrefixSpan(minSupport=0.5, maxPatternLength=5)
        >>> prefixSpan.findFrequentSequentialPatterns(df).sort("sequence").show(truncate=False)
        +----------+----+
        |sequence  |freq|
        +----------+----+
        |[[1]]     |3   |
        |[[1], [3]]|2   |
        |[[1, 2]]  |3   |
        |[[2]]     |3   |
        |[[3]]     |2   |
        +----------+----+

        .. versionadded:: 2.4.0
        """
        self._transfer_params_to_java()
        jdf = self._java_obj.findFrequentSequentialPatterns(dataset._jdf)
        return DataFrame(jdf, dataset.sql_ctx)