[SPARK-7678] [ML] Fix default random seed in HasSeed

Changed shared param HasSeed to have default based on hashCode of class name, instead of random number.
Also, removed fixed random seeds from Word2Vec and ALS.

CC: mengxr

Author: Joseph K. Bradley <[email protected]>

Closes apache#6251 from jkbradley/scala-fixed-seed and squashes the following commits:

0e37184 [Joseph K. Bradley] Fixed Word2VecSuite, ALSSuite in spark.ml to use original fixed random seeds
678ec3a [Joseph K. Bradley] Removed fixed random seeds from Word2Vec and ALS. Changed shared param HasSeed to have default based on hashCode of class name, instead of random number.

mllib/src/main/scala/org/apache/spark/ml/feature/Word2Vec.scala

@@ -68,7 +68,6 @@ private[feature] trait Word2VecBase extends Params
 
   setDefault(stepSize -> 0.025)
   setDefault(maxIter -> 1)
-  setDefault(seed -> 42L)
 
   /**
    * Validate and transform the input schema.

mllib/src/main/scala/org/apache/spark/ml/param/shared/SharedParamsCodeGen.scala

@@ -53,7 +53,7 @@ private[shared] object SharedParamsCodeGen {
       ParamDesc[Int]("checkpointInterval", "checkpoint interval (>= 1)",
         isValid = "ParamValidators.gtEq(1)"),
       ParamDesc[Boolean]("fitIntercept", "whether to fit an intercept term", Some("true")),
-      ParamDesc[Long]("seed", "random seed", Some("Utils.random.nextLong()")),
+      ParamDesc[Long]("seed", "random seed", Some("this.getClass.getName.hashCode.toLong")),
       ParamDesc[Double]("elasticNetParam", "the ElasticNet mixing parameter, in range [0, 1]." +
         " For alpha = 0, the penalty is an L2 penalty. For alpha = 1, it is an L1 penalty.",
         isValid = "ParamValidators.inRange(0, 1)"),

mllib/src/main/scala/org/apache/spark/ml/param/shared/sharedParams.scala

@@ -232,7 +232,7 @@ private[ml] trait HasFitIntercept extends Params {
 }
 
 /**
- * (private[ml]) Trait for shared param seed (default: Utils.random.nextLong()).
+ * (private[ml]) Trait for shared param seed (default: this.getClass.getName.hashCode.toLong).
  */
 private[ml] trait HasSeed extends Params {
 
@@ -242,7 +242,7 @@ private[ml] trait HasSeed extends Params {
    */
   final val seed: LongParam = new LongParam(this, "seed", "random seed")
 
-  setDefault(seed, Utils.random.nextLong())
+  setDefault(seed, this.getClass.getName.hashCode.toLong)
 
   /** @group getParam */
   final def getSeed: Long = $(seed)

mllib/src/main/scala/org/apache/spark/ml/recommendation/ALS.scala

@@ -148,7 +148,7 @@ private[recommendation] trait ALSParams extends Params with HasMaxIter with HasR
 
   setDefault(rank -> 10, maxIter -> 10, regParam -> 0.1, numUserBlocks -> 10, numItemBlocks -> 10,
     implicitPrefs -> false, alpha -> 1.0, userCol -> "user", itemCol -> "item",
-    ratingCol -> "rating", nonnegative -> false, checkpointInterval -> 10, seed -> 0L)
+    ratingCol -> "rating", nonnegative -> false, checkpointInterval -> 10)
 
   /**
    * Validates and transforms the input schema.

mllib/src/test/scala/org/apache/spark/ml/feature/Word2VecSuite.scala

@@ -52,6 +52,7 @@ class Word2VecSuite extends FunSuite with MLlibTestSparkContext {
       .setVectorSize(3)
       .setInputCol("text")
       .setOutputCol("result")
+      .setSeed(42L)
       .fit(docDF)
 
     model.transform(docDF).select("result", "expected").collect().foreach {

mllib/src/test/scala/org/apache/spark/ml/recommendation/ALSSuite.scala

@@ -345,6 +345,7 @@ class ALSSuite extends FunSuite with MLlibTestSparkContext with Logging {
       .setImplicitPrefs(implicitPrefs)
       .setNumUserBlocks(numUserBlocks)
       .setNumItemBlocks(numItemBlocks)
+      .setSeed(0)
     val alpha = als.getAlpha
     val model = als.fit(training.toDF())
     val predictions = model.transform(test.toDF())
@@ -425,17 +426,18 @@ class ALSSuite extends FunSuite with MLlibTestSparkContext with Logging {
     val (ratings, _) = genImplicitTestData(numUsers = 20, numItems = 40, rank = 2, noiseStd = 0.01)
 
     val longRatings = ratings.map(r => Rating(r.user.toLong, r.item.toLong, r.rating))
-    val (longUserFactors, _) = ALS.train(longRatings, rank = 2, maxIter = 4)
+    val (longUserFactors, _) = ALS.train(longRatings, rank = 2, maxIter = 4, seed = 0)
     assert(longUserFactors.first()._1.getClass === classOf[Long])
 
     val strRatings = ratings.map(r => Rating(r.user.toString, r.item.toString, r.rating))
-    val (strUserFactors, _) = ALS.train(strRatings, rank = 2, maxIter = 4)
+    val (strUserFactors, _) = ALS.train(strRatings, rank = 2, maxIter = 4, seed = 0)
     assert(strUserFactors.first()._1.getClass === classOf[String])
   }
 
   test("nonnegative constraint") {
     val (ratings, _) = genImplicitTestData(numUsers = 20, numItems = 40, rank = 2, noiseStd = 0.01)
-    val (userFactors, itemFactors) = ALS.train(ratings, rank = 2, maxIter = 4, nonnegative = true)
+    val (userFactors, itemFactors) =
+      ALS.train(ratings, rank = 2, maxIter = 4, nonnegative = true, seed = 0)
     def isNonnegative(factors: RDD[(Int, Array[Float])]): Boolean = {
       factors.values.map { _.forall(_ >= 0.0) }.reduce(_ && _)
     }
@@ -459,7 +461,7 @@ class ALSSuite extends FunSuite with MLlibTestSparkContext with Logging {
   test("partitioner in returned factors") {
     val (ratings, _) = genImplicitTestData(numUsers = 20, numItems = 40, rank = 2, noiseStd = 0.01)
     val (userFactors, itemFactors) = ALS.train(
-      ratings, rank = 2, maxIter = 4, numUserBlocks = 3, numItemBlocks = 4)
+      ratings, rank = 2, maxIter = 4, numUserBlocks = 3, numItemBlocks = 4, seed = 0)
     for ((tpe, factors) <- Seq(("User", userFactors), ("Item", itemFactors))) {
       assert(userFactors.partitioner.isDefined, s"$tpe factors should have partitioner.")
       val part = userFactors.partitioner.get
@@ -476,8 +478,8 @@ class ALSSuite extends FunSuite with MLlibTestSparkContext with Logging {
 
   test("als with large number of iterations") {
     val (ratings, _) = genExplicitTestData(numUsers = 4, numItems = 4, rank = 1)
-    ALS.train(ratings, rank = 1, maxIter = 50, numUserBlocks = 2, numItemBlocks = 2)
-    ALS.train(
-      ratings, rank = 1, maxIter = 50, numUserBlocks = 2, numItemBlocks = 2, implicitPrefs = true)
+    ALS.train(ratings, rank = 1, maxIter = 50, numUserBlocks = 2, numItemBlocks = 2, seed = 0)
+    ALS.train(ratings, rank = 1, maxIter = 50, numUserBlocks = 2, numItemBlocks = 2,
+      implicitPrefs = true, seed = 0)
   }
 }