Merge branch 'develop'

diff --git a/LICENSE.txt b/LICENSE.txt
new file mode 100644
index 0000000..d645695
--- /dev/null
+++ b/LICENSE.txt
@@ -0,0 +1,202 @@
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diff --git a/README.md b/README.md
index f824876..55efb1c 100644
--- a/README.md
+++ b/README.md
@@ -7,6 +7,13 @@
 
 ## Versions
 
+### v0.12.0-incubating
+
+- Bump version number to track PredictionIO version
+- Sets default build targets according to PredictionIO
+- Add checkpoint parameters
+- Fix warnings and use of case class
+
 ### v0.11.0-incubating
 
 - Bump version number to track PredictionIO version
diff --git a/build.sbt b/build.sbt
index a7cb20c..7ca9a06 100644
--- a/build.sbt
+++ b/build.sbt
@@ -1,6 +1,6 @@
 name := "template-scala-parallel-recommendation"
 
+scalaVersion := "2.11.8"
 libraryDependencies ++= Seq(
-  "org.apache.predictionio" %% "apache-predictionio-core" % "0.11.0-incubating" % "provided",
-  "org.apache.spark"        %% "spark-core"               % "1.3.0" % "provided",
-  "org.apache.spark"        %% "spark-mllib"              % "1.3.0" % "provided")
+  "org.apache.predictionio" %% "apache-predictionio-core" % "0.12.0-incubating" % "provided",
+  "org.apache.spark"        %% "spark-mllib"              % "2.1.1" % "provided")
diff --git a/project/assembly.sbt b/project/assembly.sbt
index e17409e..15a88b0 100644
--- a/project/assembly.sbt
+++ b/project/assembly.sbt
@@ -1 +1 @@
-addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.14.4")
+addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.14.5")
diff --git a/project/build.properties b/project/build.properties
index 64317fd..c091b86 100644
--- a/project/build.properties
+++ b/project/build.properties
@@ -1 +1 @@
-sbt.version=0.13.15
+sbt.version=0.13.16
diff --git a/src/main/scala/ALSAlgorithm.scala b/src/main/scala/ALSAlgorithm.scala
index b53a9af..9fa8958 100644
--- a/src/main/scala/ALSAlgorithm.scala
+++ b/src/main/scala/ALSAlgorithm.scala
@@ -5,7 +5,6 @@
 import org.apache.predictionio.data.storage.BiMap
 
 import org.apache.spark.SparkContext
-import org.apache.spark.SparkContext._
 import org.apache.spark.rdd.RDD
 import org.apache.spark.mllib.recommendation.ALS
 import org.apache.spark.mllib.recommendation.{Rating => MLlibRating}
@@ -27,7 +26,8 @@
   if (ap.numIterations > 30) {
     logger.warn(
       s"ALSAlgorithmParams.numIterations > 30, current: ${ap.numIterations}. " +
-      s"There is a chance of running to StackOverflowException. Lower this number to remedy it")
+      s"There is a chance of running to StackOverflowException." +
+      s"To remedy it, set lower numIterations or checkpoint parameters.")
   }
 
   def train(sc: SparkContext, data: PreparedData): ALSModel = {
@@ -48,24 +48,23 @@
     // seed for MLlib ALS
     val seed = ap.seed.getOrElse(System.nanoTime)
 
-    // If you only have one type of implicit event (Eg. "view" event only),
-    // replace ALS.train(...) with
-    //val m = ALS.trainImplicit(
-      //ratings = mllibRatings,
-      //rank = ap.rank,
-      //iterations = ap.numIterations,
-      //lambda = ap.lambda,
-      //blocks = -1,
-      //alpha = 1.0,
-      //seed = seed)
+    // Set checkpoint directory
+    // sc.setCheckpointDir("checkpoint")
 
-    val m = ALS.train(
-      ratings = mllibRatings,
-      rank = ap.rank,
-      iterations = ap.numIterations,
-      lambda = ap.lambda,
-      blocks = -1,
-      seed = seed)
+    // If you only have one type of implicit event (Eg. "view" event only),
+    // set implicitPrefs to true
+    val implicitPrefs = false
+    val als = new ALS()
+    als.setUserBlocks(-1)
+    als.setProductBlocks(-1)
+    als.setRank(ap.rank)
+    als.setIterations(ap.numIterations)
+    als.setLambda(ap.lambda)
+    als.setImplicitPrefs(implicitPrefs)
+    als.setAlpha(1.0)
+    als.setSeed(seed)
+    als.setCheckpointInterval(10)
+    val m = als.run(mllibRatings)
 
     new ALSModel(
       rank = m.rank,
@@ -84,10 +83,10 @@
       // index. Convert it to String ID for returning PredictedResult
       val itemScores = model.recommendProducts(userInt, query.num)
         .map (r => ItemScore(itemIntStringMap(r.product), r.rating))
-      new PredictedResult(itemScores)
+      PredictedResult(itemScores)
     }.getOrElse{
       logger.info(s"No prediction for unknown user ${query.user}.")
-      new PredictedResult(Array.empty)
+      PredictedResult(Array.empty)
     }
   }
 
diff --git a/src/main/scala/ALSModel.scala b/src/main/scala/ALSModel.scala
index afec745..e0e6a9f 100644
--- a/src/main/scala/ALSModel.scala
+++ b/src/main/scala/ALSModel.scala
@@ -5,12 +5,11 @@
 
 import org.example.recommendation.ALSAlgorithmParams
 
-import org.apache.predictionio.controller.IPersistentModel
-import org.apache.predictionio.controller.IPersistentModelLoader
+import org.apache.predictionio.controller.PersistentModel
+import org.apache.predictionio.controller.PersistentModelLoader
 import org.apache.predictionio.data.storage.BiMap
 
 import org.apache.spark.SparkContext
-import org.apache.spark.SparkContext._
 import org.apache.spark.rdd.RDD
 
 class ALSModel(
@@ -20,7 +19,7 @@
     val userStringIntMap: BiMap[String, Int],
     val itemStringIntMap: BiMap[String, Int])
   extends MatrixFactorizationModel(rank, userFeatures, productFeatures)
-  with IPersistentModel[ALSAlgorithmParams] {
+  with PersistentModel[ALSAlgorithmParams] {
 
   def save(id: String, params: ALSAlgorithmParams,
     sc: SparkContext): Boolean = {
@@ -48,7 +47,7 @@
 }
 
 object ALSModel
-  extends IPersistentModelLoader[ALSAlgorithmParams, ALSModel] {
+  extends PersistentModelLoader[ALSAlgorithmParams, ALSModel] {
   def apply(id: String, params: ALSAlgorithmParams,
     sc: Option[SparkContext]) = {
     new ALSModel(
diff --git a/src/main/scala/DataSource.scala b/src/main/scala/DataSource.scala
index 7f7b4a1..75bfac1 100644
--- a/src/main/scala/DataSource.scala
+++ b/src/main/scala/DataSource.scala
@@ -2,13 +2,11 @@
 
 import org.apache.predictionio.controller.PDataSource
 import org.apache.predictionio.controller.EmptyEvaluationInfo
-import org.apache.predictionio.controller.EmptyActualResult
 import org.apache.predictionio.controller.Params
 import org.apache.predictionio.data.storage.Event
 import org.apache.predictionio.data.store.PEventStore
 
 import org.apache.spark.SparkContext
-import org.apache.spark.SparkContext._
 import org.apache.spark.rdd.RDD
 
 import grizzled.slf4j.Logger
diff --git a/src/main/scala/Engine.scala b/src/main/scala/Engine.scala
index 20a5521..71e09bf 100644
--- a/src/main/scala/Engine.scala
+++ b/src/main/scala/Engine.scala
@@ -1,27 +1,27 @@
 package org.example.recommendation
 
-import org.apache.predictionio.controller.IEngineFactory
+import org.apache.predictionio.controller.EngineFactory
 import org.apache.predictionio.controller.Engine
 
 case class Query(
   user: String,
   num: Int
-) extends Serializable
+)
 
 case class PredictedResult(
   itemScores: Array[ItemScore]
-) extends Serializable
+)
 
 case class ActualResult(
   ratings: Array[Rating]
-) extends Serializable
+)
 
 case class ItemScore(
   item: String,
   score: Double
-) extends Serializable
+)
 
-object RecommendationEngine extends IEngineFactory {
+object RecommendationEngine extends EngineFactory {
   def apply() = {
     new Engine(
       classOf[DataSource],
diff --git a/src/main/scala/Evaluation.scala b/src/main/scala/Evaluation.scala
index e0eebe1..acc85ff 100644
--- a/src/main/scala/Evaluation.scala
+++ b/src/main/scala/Evaluation.scala
@@ -24,12 +24,11 @@
     // If there is no positive results, Precision is undefined. We don't consider this case in the
     // metrics, hence we return None.
     if (positives.size == 0) {
-      return None
+      None
+    } else {
+      val tpCount: Int = p.itemScores.take(k).filter(is => positives(is.item)).size
+      Some(tpCount.toDouble / math.min(k, positives.size))
     }
-
-    val tpCount: Int = p.itemScores.take(k).filter(is => positives(is.item)).size
-
-    Some(tpCount.toDouble / math.min(k, positives.size))
   }
 }
 
diff --git a/src/main/scala/Preparator.scala b/src/main/scala/Preparator.scala
index 0e20c62..5e3a653 100644
--- a/src/main/scala/Preparator.scala
+++ b/src/main/scala/Preparator.scala
@@ -3,7 +3,6 @@
 import org.apache.predictionio.controller.PPreparator
 
 import org.apache.spark.SparkContext
-import org.apache.spark.SparkContext._
 import org.apache.spark.rdd.RDD
 
 class Preparator