[SPARK-10386][MLLIB] PrefixSpanModel supports save/load

```PrefixSpanModel``` supports ```save/load```. It's similar with #9267.

cc jkbradley

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #10664 from yanboliang/spark-10386.

2 files changed, 68 insertions, 0 deletions

diff --git a/mllib/src/test/java/org/apache/spark/mllib/fpm/JavaPrefixSpanSuite.java b/mllib/src/test/java/org/apache/spark/mllib/fpm/JavaPrefixSpanSuite.java
index 34daf5fbde..8a67793abc 100644
--- a/mllib/src/test/java/org/apache/spark/mllib/fpm/JavaPrefixSpanSuite.java
+++ b/mllib/src/test/java/org/apache/spark/mllib/fpm/JavaPrefixSpanSuite.java
@@ -17,6 +17,7 @@
 
 package org.apache.spark.mllib.fpm;
 
+import java.io.File;
 import java.util.Arrays;
 import java.util.List;
 
@@ -28,6 +29,7 @@ import org.junit.Test;
 import org.apache.spark.api.java.JavaRDD;
 import org.apache.spark.api.java.JavaSparkContext;
 import org.apache.spark.mllib.fpm.PrefixSpan.FreqSequence;
+import org.apache.spark.util.Utils;
 
 public class JavaPrefixSpanSuite {
   private transient JavaSparkContext sc;
@@ -64,4 +66,39 @@ public class JavaPrefixSpanSuite {
       long freq = freqSeq.freq();
     }
   }
+
+  @Test
+  public void runPrefixSpanSaveLoad() {
+    JavaRDD<List<List<Integer>>> sequences = sc.parallelize(Arrays.asList(
+      Arrays.asList(Arrays.asList(1, 2), Arrays.asList(3)),
+      Arrays.asList(Arrays.asList(1), Arrays.asList(3, 2), Arrays.asList(1, 2)),
+      Arrays.asList(Arrays.asList(1, 2), Arrays.asList(5)),
+      Arrays.asList(Arrays.asList(6))
+    ), 2);
+    PrefixSpan prefixSpan = new PrefixSpan()
+      .setMinSupport(0.5)
+      .setMaxPatternLength(5);
+    PrefixSpanModel<Integer> model = prefixSpan.run(sequences);
+
+    File tempDir = Utils.createTempDir(
+      System.getProperty("java.io.tmpdir"), "JavaPrefixSpanSuite");
+    String outputPath = tempDir.getPath();
+
+    try {
+      model.save(sc.sc(), outputPath);
+      PrefixSpanModel newModel = PrefixSpanModel.load(sc.sc(), outputPath);
+      JavaRDD<FreqSequence<Integer>> freqSeqs = newModel.freqSequences().toJavaRDD();
+      List<FreqSequence<Integer>> localFreqSeqs = freqSeqs.collect();
+      Assert.assertEquals(5, localFreqSeqs.size());
+      // Check that each frequent sequence could be materialized.
+      for (PrefixSpan.FreqSequence<Integer> freqSeq: localFreqSeqs) {
+        List<List<Integer>> seq = freqSeq.javaSequence();
+        long freq = freqSeq.freq();
+      }
+    } finally {
+      Utils.deleteRecursively(tempDir);
+    }
+
+
+  }
 }
diff --git a/mllib/src/test/scala/org/apache/spark/mllib/fpm/PrefixSpanSuite.scala b/mllib/src/test/scala/org/apache/spark/mllib/fpm/PrefixSpanSuite.scala
index a83e543859..6d8c7b47d8 100644
--- a/mllib/src/test/scala/org/apache/spark/mllib/fpm/PrefixSpanSuite.scala
+++ b/mllib/src/test/scala/org/apache/spark/mllib/fpm/PrefixSpanSuite.scala
@@ -18,6 +18,7 @@ package org.apache.spark.mllib.fpm
 
 import org.apache.spark.SparkFunSuite
 import org.apache.spark.mllib.util.MLlibTestSparkContext
+import org.apache.spark.util.Utils
 
 class PrefixSpanSuite extends SparkFunSuite with MLlibTestSparkContext {
 
@@ -357,6 +358,36 @@ class PrefixSpanSuite extends SparkFunSuite with MLlibTestSparkContext {
     compareResults(expected, model.freqSequences.collect())
   }
 
+  test("model save/load") {
+    val sequences = Seq(
+      Array(Array(1, 2), Array(3)),
+      Array(Array(1), Array(3, 2), Array(1, 2)),
+      Array(Array(1, 2), Array(5)),
+      Array(Array(6)))
+    val rdd = sc.parallelize(sequences, 2).cache()
+
+    val prefixSpan = new PrefixSpan()
+      .setMinSupport(0.5)
+      .setMaxPatternLength(5)
+    val model = prefixSpan.run(rdd)
+
+    val tempDir = Utils.createTempDir()
+    val path = tempDir.toURI.toString
+    try {
+      model.save(sc, path)
+      val newModel = PrefixSpanModel.load(sc, path)
+      val originalSet = model.freqSequences.collect().map { x =>
+        (x.sequence.map(_.toSet).toSeq, x.freq)
+      }.toSet
+      val newSet = newModel.freqSequences.collect().map { x =>
+        (x.sequence.map(_.toSet).toSeq, x.freq)
+      }.toSet
+      assert(originalSet === newSet)
+    } finally {
+      Utils.deleteRecursively(tempDir)
+    }
+  }
+
   private def compareResults[Item](
       expectedValue: Array[(Array[Array[Item]], Long)],
       actualValue: Array[PrefixSpan.FreqSequence[Item]]): Unit = {