/
Word2Vec.scala
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/
Word2Vec.scala
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/*
* 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.feature
import org.apache.hadoop.fs.Path
import org.apache.spark.annotation.Since
import org.apache.spark.ml.{Estimator, Model}
import org.apache.spark.ml.linalg.{BLAS, Vector, Vectors, VectorUDT}
import org.apache.spark.ml.param._
import org.apache.spark.ml.param.shared._
import org.apache.spark.ml.util._
import org.apache.spark.mllib.feature
import org.apache.spark.mllib.linalg.VectorImplicits._
import org.apache.spark.sql.{DataFrame, Dataset, SparkSession}
import org.apache.spark.sql.functions._
import org.apache.spark.sql.types._
import org.apache.spark.util.{Utils, VersionUtils}
/**
* Params for [[Word2Vec]] and [[Word2VecModel]].
*/
private[feature] trait Word2VecBase extends Params
with HasInputCol with HasOutputCol with HasMaxIter with HasStepSize with HasSeed {
/**
* The dimension of the code that you want to transform from words.
* Default: 100
* @group param
*/
final val vectorSize = new IntParam(
this, "vectorSize", "the dimension of codes after transforming from words (> 0)",
ParamValidators.gt(0))
setDefault(vectorSize -> 100)
/** @group getParam */
def getVectorSize: Int = $(vectorSize)
/**
* The window size (context words from [-window, window]).
* Default: 5
* @group expertParam
*/
final val windowSize = new IntParam(
this, "windowSize", "the window size (context words from [-window, window]) (> 0)",
ParamValidators.gt(0))
setDefault(windowSize -> 5)
/** @group expertGetParam */
def getWindowSize: Int = $(windowSize)
/**
* Number of partitions for sentences of words.
* Default: 1
* @group param
*/
final val numPartitions = new IntParam(
this, "numPartitions", "number of partitions for sentences of words (> 0)",
ParamValidators.gt(0))
setDefault(numPartitions -> 1)
/** @group getParam */
def getNumPartitions: Int = $(numPartitions)
/**
* The minimum number of times a token must appear to be included in the word2vec model's
* vocabulary.
* Default: 5
* @group param
*/
final val minCount = new IntParam(this, "minCount", "the minimum number of times a token must " +
"appear to be included in the word2vec model's vocabulary (>= 0)", ParamValidators.gtEq(0))
setDefault(minCount -> 5)
/** @group getParam */
def getMinCount: Int = $(minCount)
/**
* Sets the maximum length (in words) of each sentence in the input data.
* Any sentence longer than this threshold will be divided into chunks of
* up to `maxSentenceLength` size.
* Default: 1000
* @group param
*/
final val maxSentenceLength = new IntParam(this, "maxSentenceLength", "Maximum length " +
"(in words) of each sentence in the input data. Any sentence longer than this threshold will " +
"be divided into chunks up to the size (> 0)", ParamValidators.gt(0))
setDefault(maxSentenceLength -> 1000)
/** @group getParam */
def getMaxSentenceLength: Int = $(maxSentenceLength)
setDefault(stepSize -> 0.025)
setDefault(maxIter -> 1)
/**
* Validate and transform the input schema.
*/
protected def validateAndTransformSchema(schema: StructType): StructType = {
val typeCandidates = List(new ArrayType(StringType, true), new ArrayType(StringType, false))
SchemaUtils.checkColumnTypes(schema, $(inputCol), typeCandidates)
SchemaUtils.appendColumn(schema, $(outputCol), new VectorUDT)
}
}
/**
* Word2Vec trains a model of `Map(String, Vector)`, i.e. transforms a word into a code for further
* natural language processing or machine learning process.
*/
@Since("1.4.0")
final class Word2Vec @Since("1.4.0") (
@Since("1.4.0") override val uid: String)
extends Estimator[Word2VecModel] with Word2VecBase with DefaultParamsWritable {
@Since("1.4.0")
def this() = this(Identifiable.randomUID("w2v"))
/** @group setParam */
@Since("1.4.0")
def setInputCol(value: String): this.type = set(inputCol, value)
/** @group setParam */
@Since("1.4.0")
def setOutputCol(value: String): this.type = set(outputCol, value)
/** @group setParam */
@Since("1.4.0")
def setVectorSize(value: Int): this.type = set(vectorSize, value)
/** @group expertSetParam */
@Since("1.6.0")
def setWindowSize(value: Int): this.type = set(windowSize, value)
/** @group setParam */
@Since("1.4.0")
def setStepSize(value: Double): this.type = set(stepSize, value)
/** @group setParam */
@Since("1.4.0")
def setNumPartitions(value: Int): this.type = set(numPartitions, value)
/** @group setParam */
@Since("1.4.0")
def setMaxIter(value: Int): this.type = set(maxIter, value)
/** @group setParam */
@Since("1.4.0")
def setSeed(value: Long): this.type = set(seed, value)
/** @group setParam */
@Since("1.4.0")
def setMinCount(value: Int): this.type = set(minCount, value)
/** @group setParam */
@Since("2.0.0")
def setMaxSentenceLength(value: Int): this.type = set(maxSentenceLength, value)
@Since("2.0.0")
override def fit(dataset: Dataset[_]): Word2VecModel = {
transformSchema(dataset.schema, logging = true)
val input = dataset.select($(inputCol)).rdd.map(_.getAs[Seq[String]](0))
val wordVectors = new feature.Word2Vec()
.setLearningRate($(stepSize))
.setMinCount($(minCount))
.setNumIterations($(maxIter))
.setNumPartitions($(numPartitions))
.setSeed($(seed))
.setVectorSize($(vectorSize))
.setWindowSize($(windowSize))
.setMaxSentenceLength($(maxSentenceLength))
.fit(input)
copyValues(new Word2VecModel(uid, wordVectors).setParent(this))
}
@Since("1.4.0")
override def transformSchema(schema: StructType): StructType = {
validateAndTransformSchema(schema)
}
@Since("1.4.1")
override def copy(extra: ParamMap): Word2Vec = defaultCopy(extra)
}
@Since("1.6.0")
object Word2Vec extends DefaultParamsReadable[Word2Vec] {
@Since("1.6.0")
override def load(path: String): Word2Vec = super.load(path)
}
/**
* Model fitted by [[Word2Vec]].
*/
@Since("1.4.0")
class Word2VecModel private[ml] (
@Since("1.4.0") override val uid: String,
@transient private val wordVectors: feature.Word2VecModel)
extends Model[Word2VecModel] with Word2VecBase with MLWritable {
import Word2VecModel._
/**
* Returns a dataframe with two fields, "word" and "vector", with "word" being a String and
* and the vector the DenseVector that it is mapped to.
*/
@Since("1.5.0")
@transient lazy val getVectors: DataFrame = {
val spark = SparkSession.builder().getOrCreate()
val wordVec = wordVectors.getVectors.mapValues(vec => Vectors.dense(vec.map(_.toDouble)))
spark.createDataFrame(wordVec.toSeq).toDF("word", "vector")
}
/**
* Find "num" number of words closest in similarity to the given word, not
* including the word itself.
* @return a dataframe with columns "word" and "similarity" of the word and the cosine
* similarities between the synonyms and the given word.
*/
@Since("1.5.0")
def findSynonyms(word: String, num: Int): DataFrame = {
val spark = SparkSession.builder().getOrCreate()
spark.createDataFrame(findSynonymsArray(word, num)).toDF("word", "similarity")
}
/**
* Find "num" number of words whose vector representation is most similar to the supplied vector.
* If the supplied vector is the vector representation of a word in the model's vocabulary,
* that word will be in the results.
* @return a dataframe with columns "word" and "similarity" of the word and the cosine
* similarities between the synonyms and the given word vector.
*/
@Since("2.0.0")
def findSynonyms(vec: Vector, num: Int): DataFrame = {
val spark = SparkSession.builder().getOrCreate()
spark.createDataFrame(findSynonymsArray(vec, num)).toDF("word", "similarity")
}
/**
* Find "num" number of words whose vector representation is most similar to the supplied vector.
* If the supplied vector is the vector representation of a word in the model's vocabulary,
* that word will be in the results.
* @return an array of the words and the cosine similarities between the synonyms given
* word vector.
*/
@Since("2.2.0")
def findSynonymsArray(vec: Vector, num: Int): Array[(String, Double)] = {
wordVectors.findSynonyms(vec, num)
}
/**
* Find "num" number of words closest in similarity to the given word, not
* including the word itself.
* @return an array of the words and the cosine similarities between the synonyms given
* word vector.
*/
@Since("2.2.0")
def findSynonymsArray(word: String, num: Int): Array[(String, Double)] = {
wordVectors.findSynonyms(word, num)
}
/** @group setParam */
@Since("1.4.0")
def setInputCol(value: String): this.type = set(inputCol, value)
/** @group setParam */
@Since("1.4.0")
def setOutputCol(value: String): this.type = set(outputCol, value)
/**
* Transform a sentence column to a vector column to represent the whole sentence. The transform
* is performed by averaging all word vectors it contains.
*/
@Since("2.0.0")
override def transform(dataset: Dataset[_]): DataFrame = {
transformSchema(dataset.schema, logging = true)
val vectors = wordVectors.getVectors
.mapValues(vv => Vectors.dense(vv.map(_.toDouble)))
.map(identity) // mapValues doesn't return a serializable map (SI-7005)
val bVectors = dataset.sparkSession.sparkContext.broadcast(vectors)
val d = $(vectorSize)
val word2Vec = udf { sentence: Seq[String] =>
if (sentence.isEmpty) {
Vectors.sparse(d, Array.empty[Int], Array.empty[Double])
} else {
val sum = Vectors.zeros(d)
sentence.foreach { word =>
bVectors.value.get(word).foreach { v =>
BLAS.axpy(1.0, v, sum)
}
}
BLAS.scal(1.0 / sentence.size, sum)
sum
}
}
dataset.withColumn($(outputCol), word2Vec(col($(inputCol))))
}
@Since("1.4.0")
override def transformSchema(schema: StructType): StructType = {
validateAndTransformSchema(schema)
}
@Since("1.4.1")
override def copy(extra: ParamMap): Word2VecModel = {
val copied = new Word2VecModel(uid, wordVectors)
copyValues(copied, extra).setParent(parent)
}
@Since("1.6.0")
override def write: MLWriter = new Word2VecModelWriter(this)
}
@Since("1.6.0")
object Word2VecModel extends MLReadable[Word2VecModel] {
private case class Data(word: String, vector: Array[Float])
private[Word2VecModel]
class Word2VecModelWriter(instance: Word2VecModel) extends MLWriter {
override protected def saveImpl(path: String): Unit = {
DefaultParamsWriter.saveMetadata(instance, path, sc)
val wordVectors = instance.wordVectors.getVectors
val dataPath = new Path(path, "data").toString
val bufferSizeInBytes = Utils.byteStringAsBytes(
sc.conf.get("spark.kryoserializer.buffer.max", "64m"))
val numPartitions = Word2VecModelWriter.calculateNumberOfPartitions(
bufferSizeInBytes, instance.wordVectors.wordIndex.size, instance.getVectorSize)
val spark = sparkSession
import spark.implicits._
spark.createDataset[(String, Array[Float])](wordVectors.toSeq)
.repartition(numPartitions)
.map { case (word, vector) => Data(word, vector) }
.toDF()
.write
.parquet(dataPath)
}
}
private[feature]
object Word2VecModelWriter {
/**
* Calculate the number of partitions to use in saving the model.
* [SPARK-11994] - We want to partition the model in partitions smaller than
* spark.kryoserializer.buffer.max
* @param bufferSizeInBytes Set to spark.kryoserializer.buffer.max
* @param numWords Vocab size
* @param vectorSize Vector length for each word
*/
def calculateNumberOfPartitions(
bufferSizeInBytes: Long,
numWords: Int,
vectorSize: Int): Int = {
val floatSize = 4L // Use Long to help avoid overflow
val averageWordSize = 15
// Calculate the approximate size of the model.
// Assuming an average word size of 15 bytes, the formula is:
// (floatSize * vectorSize + 15) * numWords
val approximateSizeInBytes = (floatSize * vectorSize + averageWordSize) * numWords
val numPartitions = (approximateSizeInBytes / bufferSizeInBytes) + 1
require(numPartitions < 10e8, s"Word2VecModel calculated that it needs $numPartitions " +
s"partitions to save this model, which is too large. Try increasing " +
s"spark.kryoserializer.buffer.max so that Word2VecModel can use fewer partitions.")
numPartitions.toInt
}
}
private class Word2VecModelReader extends MLReader[Word2VecModel] {
private val className = classOf[Word2VecModel].getName
override def load(path: String): Word2VecModel = {
val spark = sparkSession
import spark.implicits._
val metadata = DefaultParamsReader.loadMetadata(path, sc, className)
val (major, minor) = VersionUtils.majorMinorVersion(metadata.sparkVersion)
val dataPath = new Path(path, "data").toString
val oldModel = if (major < 2 || (major == 2 && minor < 2)) {
val data = spark.read.parquet(dataPath)
.select("wordIndex", "wordVectors")
.head()
val wordIndex = data.getAs[Map[String, Int]](0)
val wordVectors = data.getAs[Seq[Float]](1).toArray
new feature.Word2VecModel(wordIndex, wordVectors)
} else {
val wordVectorsMap = spark.read.parquet(dataPath).as[Data]
.collect()
.map(wordVector => (wordVector.word, wordVector.vector))
.toMap
new feature.Word2VecModel(wordVectorsMap)
}
val model = new Word2VecModel(metadata.uid, oldModel)
DefaultParamsReader.getAndSetParams(model, metadata)
model
}
}
@Since("1.6.0")
override def read: MLReader[Word2VecModel] = new Word2VecModelReader
@Since("1.6.0")
override def load(path: String): Word2VecModel = super.load(path)
}