[SPARK-6053][MLLIB] support save/load in PySpark's ALS

[mengxr]

A simple wrapper to save/load MatrixFactorizationModel in Python. @jkbradley

[SparkQA]

Test build #28056 has started for PR 4811 at commit 282ec8d.

• This patch merges cleanly.

[SparkQA]

Test build #28056 has finished for PR 4811 at commit 282ec8d.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • class MatrixFactorizationModel(JavaModelWrapper, Saveable, JavaLoader):
  • class Saveable(object):
  • class Loader(object):
  • class JavaLoader(Loader):
  • java_class = ".".join([java_package, cls.__name__])

[AmplabJenkins]

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[jkbradley]

I messed up not passing sc to save/load. Is this patch going into 1.3? If not, then I'll submit a separate patch fixing the documentation (which will conflict a little).

[mengxr]

If we have couple days before RC2, this would be nice to have. We use the same API as in Scala/Java and there is no real implementation in this PR. Having save/load would benefit many users.

[SparkQA]

Test build #28088 has started for PR 4811 at commit 06140a4.

• This patch merges cleanly.

[jkbradley]

Add sc to save call.
Also import MatrixFactorizationModel

[SparkQA]

Test build #28088 has finished for PR 4811 at commit 06140a4.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • class MatrixFactorizationModel(JavaModelWrapper, Saveable, JavaLoader):
  • class Saveable(object):
  • class Loader(object):
  • class JavaLoader(Loader):
  • java_class = ".".join([java_package, cls.__name__])

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/SparkPullRequestBuilder/28088/
Test PASSed.

[jkbradley]

LGTM. I ran into a bug running the example, but it seems to be coming from elsewhere. It happens when calling train---and not all the time, only sometimes:

java.lang.ClassCastException: scala.None$ cannot be cast to java.util.List
    at org.apache.spark.api.python.PythonAccumulatorParam.addInPlace(PythonRDD.scala:745)
    at org.apache.spark.Accumulable.$plus$plus$eq(Accumulators.scala:82)
    at org.apache.spark.Accumulators$$anonfun$add$2.apply(Accumulators.scala:340)
    at org.apache.spark.Accumulators$$anonfun$add$2.apply(Accumulators.scala:335)
    at scala.collection.TraversableLike$WithFilter$$anonfun$foreach$1.apply(TraversableLike.scala:772)
    at scala.collection.mutable.HashMap$$anonfun$foreach$1.apply(HashMap.scala:98)
    at scala.collection.mutable.HashMap$$anonfun$foreach$1.apply(HashMap.scala:98)
    at scala.collection.mutable.HashTable$class.foreachEntry(HashTable.scala:226)
    at scala.collection.mutable.HashMap.foreachEntry(HashMap.scala:39)
    at scala.collection.mutable.HashMap.foreach(HashMap.scala:98)
    at scala.collection.TraversableLike$WithFilter.foreach(TraversableLike.scala:771)
    at org.apache.spark.Accumulators$.add(Accumulators.scala:335)
    at org.apache.spark.scheduler.DAGScheduler.updateAccumulators(DAGScheduler.scala:892)
    at org.apache.spark.scheduler.DAGScheduler.handleTaskCompletion(DAGScheduler.scala:974)
    at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1398)
    at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1362)
    at org.apache.spark.util.EventLoop$$anon$1.run(EventLoop.scala:48)
15/02/27 14:41:29 ERROR DAGScheduler: Failed to update accumulators for ResultTask(279, 4)
java.lang.ClassCastException: scala.None$ cannot be cast to java.util.List
    at org.apache.spark.api.python.PythonAccumulatorParam.addInPlace(PythonRDD.scala:745)
    at org.apache.spark.Accumulable.$plus$plus$eq(Accumulators.scala:82)
    at org.apache.spark.Accumulators$$anonfun$add$2.apply(Accumulators.scala:340)
    at org.apache.spark.Accumulators$$anonfun$add$2.apply(Accumulators.scala:335)
    at scala.collection.TraversableLike$WithFilter$$anonfun$foreach$1.apply(TraversableLike.scala:772)
    at scala.collection.mutable.HashMap$$anonfun$foreach$1.apply(HashMap.scala:98)
    at scala.collection.mutable.HashMap$$anonfun$foreach$1.apply(HashMap.scala:98)
    at scala.collection.mutable.HashTable$class.foreachEntry(HashTable.scala:226)
    at scala.collection.mutable.HashMap.foreachEntry(HashMap.scala:39)
    at scala.collection.mutable.HashMap.foreach(HashMap.scala:98)
    at scala.collection.TraversableLike$WithFilter.foreach(TraversableLike.scala:771)
    at org.apache.spark.Accumulators$.add(Accumulators.scala:335)
    at org.apache.spark.scheduler.DAGScheduler.updateAccumulators(DAGScheduler.scala:892)
    at org.apache.spark.scheduler.DAGScheduler.handleTaskCompletion(DAGScheduler.scala:974)
    at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1398)
    at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1362)
    at org.apache.spark.util.EventLoop$$anon$1.run(EventLoop.scala:48)

I'll make a separate JIRA for it.

[jkbradley]

Made JIRA: [https://issues.apache.org/jira/browse/SPARK-6071]

[SparkQA]

Test build #28151 has started for PR 4811 at commit f135dac.

• This patch merges cleanly.

[SparkQA]

Test build #28151 has finished for PR 4811 at commit f135dac.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • class MatrixFactorizationModel(JavaModelWrapper, Saveable, JavaLoader):
  • class Saveable(object):
  • class Loader(object):
  • class JavaLoader(Loader):
  • java_class = ".".join([java_package, cls.__name__])

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/SparkPullRequestBuilder/28151/
Test PASSed.

[jkbradley]

LGTM

[mengxr]

Merged into master and branch-1.3. Thanks!