Github user jkbradley commented on a diff in the pull request:
https://github.com/apache/spark/pull/15415#discussion_r101698340
--- Diff: mllib/src/main/scala/org/apache/spark/ml/fpm/FPGrowth.scala ---
@@ -0,0 +1,327 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.ml.fpm
+
+import scala.collection.mutable.ArrayBuffer
+import scala.reflect.ClassTag
+
+import org.apache.hadoop.fs.Path
+
+import org.apache.spark.annotation.{Experimental, Since}
+import org.apache.spark.ml.{Estimator, Model}
+import org.apache.spark.ml.param._
+import org.apache.spark.ml.param.shared.{HasFeaturesCol, HasPredictionCol}
+import org.apache.spark.ml.util._
+import org.apache.spark.mllib.fpm.{AssociationRules =>
MLlibAssociationRules,
+FPGrowth => MLlibFPGrowth}
+import org.apache.spark.mllib.fpm.FPGrowth.FreqItemset
+import org.apache.spark.sql._
+import org.apache.spark.sql.types._
+
+/**
+ * Common params for FPGrowth and FPGrowthModel
+ */
+private[fpm] trait FPGrowthParams extends Params with HasFeaturesCol with
HasPredictionCol {
+
+ /**
+ * Validates and transforms the input schema.
+ * @param schema input schema
+ * @return output schema
+ */
+ protected def validateAndTransformSchema(schema: StructType): StructType
= {
+ val inputType = schema($(featuresCol)).dataType
+ require(inputType.isInstanceOf[ArrayType],
+ s"The input column must be ArrayType, but got $inputType.")
+ SchemaUtils.appendColumn(schema, $(predictionCol),
schema($(featuresCol)).dataType)
+ }
+
+ /**
+ * 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
+ * Default: 0.3
+ * @group param
+ */
+ @Since("2.2.0")
+ val minSupport: DoubleParam = new DoubleParam(this, "minSupport",
+ "the minimal support level of the frequent pattern (Default: 0.3)",
+ ParamValidators.inRange(0.0, 1.0))
+ setDefault(minSupport -> 0.3)
+
+ /** @group getParam */
+ @Since("2.2.0")
+ def getMinSupport: Double = $(minSupport)
+
+ /**
+ * Number of partitions used by parallel FP-growth
+ * @group expertParam
+ */
+ @Since("2.2.0")
+ val numPartitions: IntParam = new IntParam(this, "numPartitions",
+ "Number of partitions used by parallel FP-growth",
ParamValidators.gtEq[Int](1))
+
+ /** @group expertGetParam */
+ @Since("2.2.0")
+ def getNumPartitions: Int = $(numPartitions)
+
+ /**
+ * minimal confidence for generating Association Rule
+ * Default: 0.8
+ * @group param
+ */
+ @Since("2.2.0")
+ val minConfidence: DoubleParam = new DoubleParam(this, "minConfidence",
+ "minimal confidence for generating Association Rule (Default: 0.8)",
+ ParamValidators.inRange(0.0, 1.0))
+ setDefault(minConfidence -> 0.8)
+
+ /** @group getParam */
+ @Since("2.2.0")
+ def getMinConfidence: Double = $(minConfidence)
+
+}
+
+/**
+ * :: Experimental ::
+ * A parallel FP-growth algorithm to mine frequent itemsets.
+ *
+ * @see [[http://dx.doi.org/10.1145/1454008.1454027 Li et al., PFP:
Parallel FP-Growth for Query
+ * Recommendation]]
+ */
+@Since("2.2.0")
+@Experimental
+class FPGrowth @Since("2.2.0") (
+ @Since("2.2.0") override val uid: String)
+ extends Estimator[FPGrowthModel] with FPGrowthParams with
DefaultParamsWritable {
+
+ @Since("2.2.0")
+ def this() = this(Identifiable.randomUID("fpgrowth"))
+
+ /** @group setParam */
+ @Since("2.2.0")
+ def setMinSupport(value: Double): this.type = set(minSupport, value)
+
+ /** @group expertSetParam */
+ @Since("2.2.0")
+ def setNumPartitions(value: Int): this.type = set(numPartitions, value)
+
+ /** @group setParam
+ * minConfidence has not effect during fitting.
+ */
+ @Since("2.2.0")
+ def setMinConfidence(value: Double): this.type = set(minConfidence,
value)
+
+ /** @group setParam */
+ @Since("2.2.0")
+ def setFeaturesCol(value: String): this.type = set(featuresCol, value)
+
+ /** @group setParam */
+ @Since("2.2.0")
+ def setPredictionCol(value: String): this.type = set(predictionCol,
value)
+
+ override def fit(dataset: Dataset[_]): FPGrowthModel = {
+ genericFit(dataset)
+ }
+
+ private def genericFit[T: ClassTag](dataset: Dataset[_]): FPGrowthModel
= {
+ val data = dataset.select($(featuresCol)).rdd.map(r =>
r.getSeq[T](0).toArray)
+ val parentModel = new
MLlibFPGrowth().setMinSupport($(minSupport)).run(data)
+ val rows = parentModel.freqItemsets
+ .map(f => (f.items, f.freq))
+ .map(cols => Row(cols._1, cols._2))
+
+ val dt = dataset.schema($(featuresCol)).dataType
+ val fields = Array(StructField("items", dt, nullable = false),
+ StructField("freq", LongType, nullable = false))
+ val schema = StructType(fields)
+ val frequentItems = dataset.sparkSession.createDataFrame(rows,
schema).toDF("items", "freq")
+ copyValues(new FPGrowthModel(uid, frequentItems)).setParent(this)
+ }
+
+ @Since("2.2.0")
+ override def transformSchema(schema: StructType): StructType = {
+ validateAndTransformSchema(schema)
+ }
+
+ override def copy(extra: ParamMap): FPGrowth = defaultCopy(extra)
+}
+
+
+@Since("2.2.0")
+object FPGrowth extends DefaultParamsReadable[FPGrowth] {
+
+ @Since("2.2.0")
+ override def load(path: String): FPGrowth = super.load(path)
+}
+
+/**
+ * :: Experimental ::
+ * Model fitted by FPGrowth.
+ *
+ * @param freqItemsets frequent items in the format of DataFrame("items",
"freq")
+ */
+@Since("2.2.0")
+@Experimental
+class FPGrowthModel private[ml] (
+ @Since("2.2.0") override val uid: String,
+ val freqItemsets: DataFrame)
+ extends Model[FPGrowthModel] with FPGrowthParams with MLWritable {
+
+ /** @group setParam */
+ @Since("2.2.0")
+ def setMinConfidence(value: Double): this.type = set(minConfidence,
value)
+
+ /** @group setParam */
+ @Since("2.2.0")
+ def setFeaturesCol(value: String): this.type = set(featuresCol, value)
+
+ /** @group setParam */
+ @Since("2.2.0")
+ def setPredictionCol(value: String): this.type = set(predictionCol,
value)
+
+ /**
+ * Get association rules fitted by AssociationRules using the
minConfidence. Returns a dataframe
+ * with three fields, "antecedent", "consequent" and "confidence", where
"antecedent" and
+ * "consequent" are Array[String] and "confidence" is Double.
+ */
+ @Since("2.2.0")
+ @transient lazy val getAssociationRules: DataFrame = {
+ val freqItems = getFreqItemsets
+ AssocaitionRules.getAssocationRulesFromFP(freqItems, "items", "freq",
$(minConfidence))
+ }
+
+ /**
+ * Get frequent items fitted by FPGrowth, in the format of
DataFrame("items", "freq")
+ */
+ @Since("2.2.0")
+ @transient val getFreqItemsets: DataFrame = freqItemsets
+
+ @Since("2.2.0")
+ override def transform(dataset: Dataset[_]): DataFrame = {
+ genericTransform(dataset, getAssociationRules)
+ }
+
+ private def genericTransform[T](dataset: Dataset[_], associationRules:
DataFrame): DataFrame = {
+ // use unique id to perform the join and aggregateByKey
+ val itemsRDD = dataset.select($(featuresCol)).rdd.map(r =>
r.getSeq[T](0))
+ .distinct().zipWithUniqueId().map(_.swap).cache()
+ val rulesRDD = associationRules.rdd.map(r => (r.getSeq[T](0),
r.getSeq[T](1)))
+
+ val itemsWithConsequents = itemsRDD.cartesian(rulesRDD).map {
+ case ((id, items), (antecedent, consequent)) =>
+ val itemSet = items.toSet
+ val consequents = if (antecedent.forall(itemSet.contains(_)))
consequent else Seq.empty
+ (id, consequents)
+ }.aggregateByKey(new ArrayBuffer[T])(
+ (ar, seq) => ar ++= seq, (ar, seq) => ar ++= seq)
+
+ val mappingRDD = itemsRDD.join(itemsWithConsequents)
+ .map { case (id, (items, consequent)) => (items, consequent) }
+ .map (cols => Row(cols._1, cols._2))
+ val dt = dataset.schema($(featuresCol)).dataType
+ val fields = Array($(featuresCol), $(predictionCol))
+ .map(fieldName => StructField(fieldName, dt, nullable = true))
+ val schema = StructType(fields)
+ val mapping = dataset.sparkSession.createDataFrame(mappingRDD, schema)
+
+ dataset.join(mapping, $(featuresCol))
+ }
+
+ @Since("2.2.0")
+ override def transformSchema(schema: StructType): StructType = {
+ validateAndTransformSchema(schema)
+ }
+
+ @Since("2.2.0")
+ override def copy(extra: ParamMap): FPGrowthModel = {
+ val copied = new FPGrowthModel(uid, freqItemsets)
+ copyValues(copied, extra).setParent(this.parent)
+ }
+
+ @Since("2.2.0")
+ override def write: MLWriter = new
FPGrowthModel.FPGrowthModelWriter(this)
+}
+
+object FPGrowthModel extends MLReadable[FPGrowthModel] {
+ @Since("2.2.0")
+ override def read: MLReader[FPGrowthModel] = new FPGrowthModelReader
+
+ @Since("2.2.0")
+ override def load(path: String): FPGrowthModel = super.load(path)
+
+ /** [[MLWriter]] instance for [[FPGrowthModel]] */
+ private[FPGrowthModel]
+ class FPGrowthModelWriter(instance: FPGrowthModel) extends MLWriter {
+
+ override protected def saveImpl(path: String): Unit = {
+ // Save metadata and Params
+ DefaultParamsWriter.saveMetadata(instance, path, sc)
+ val dataPath = new Path(path, "data").toString
+ instance.freqItemsets.write.save(dataPath)
+ }
+ }
+
+ private class FPGrowthModelReader extends MLReader[FPGrowthModel] {
+
+ /** Checked against metadata when loading model */
+ private val className = classOf[FPGrowthModel].getName
+
+ override def load(path: String): FPGrowthModel = {
+ val metadata = DefaultParamsReader.loadMetadata(path, sc, className)
+ val dataPath = new Path(path, "data").toString
+ val frequentItems = sparkSession.read.load(dataPath)
+ val model = new FPGrowthModel(metadata.uid, frequentItems)
+ DefaultParamsReader.getAndSetParams(model, metadata)
+ model
+ }
+ }
+}
+
+private[fpm] object AssocaitionRules {
+
+ /**
+ * Computes the association rules with confidence above minConfidence.
+ * @param dataset DataFrame("items", "freq") containing frequent itemset
obtained from
+ * algorithms like [[FPGrowth]].
+ * @param itemsCol column name for frequent itemsets
+ * @param freqCol column name for frequent itemsets count
+ * @param minConfidence minimum confidence for the result association
rules
+ * @return a DataFrame("antecedent", "consequent", "confidence")
containing the association
+ * rules.
+ */
+ @Since("2.2.0")
--- End diff --
can remove Since annotation since the object is private
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