examples/scala-parallel-recommendation/customize-data-prep/src/main/scala/Preparator.scala

/*
 * 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
 *
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 * distributed under the License is distributed on an "AS IS" BASIS,
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package org.apache.predictionio.examples.recommendation

import org.apache.predictionio.controller.PPreparator

import org.apache.spark.SparkContext
import org.apache.spark.SparkContext._
import org.apache.spark.rdd.RDD

import scala.io.Source // ADDED
import org.apache.predictionio.controller.Params // ADDED

// ADDED CustomPreparatorParams case class
case class CustomPreparatorParams(
  filepath: String
) extends Params

class Preparator(pp: CustomPreparatorParams) // ADDED CustomPreparatorParams
  extends PPreparator[TrainingData, PreparedData] {

  def prepare(sc: SparkContext, trainingData: TrainingData): PreparedData = {
    val noTrainItems = Source.fromFile(pp.filepath).getLines.toSet // CHANGED
    val ratings = trainingData.ratings.filter( r =>
      !noTrainItems.contains(r.item)
    )
    new PreparedData(ratings)
  }
}

class PreparedData(
  val ratings: RDD[Rating]
) extends Serializable