[SPARK-5520][MLlib] Make FP-Growth implementation take generic item types (WIP)

Make FPGrowth.run API take generic item types:
`def run[Item: ClassTag, Basket <: Iterable[Item]](data: RDD[Basket]): FPGrowthModel[Item]`
so that user can invoke it by run[String, Seq[String]], run[Int, Seq[Int]], run[Int, List[Int]], etc.

Scala part is done, while java part is still in progress

Author: Jacky Li <jacky.likun@huawei.com>
Author: Jacky Li <jackylk@users.noreply.github.com>
Author: Xiangrui Meng <meng@databricks.com>

Closes #4340 from jackylk/SPARK-5520-WIP and squashes the following commits:

f5acf84 [Jacky Li] Merge pull request #2 from mengxr/SPARK-5520
63073d0 [Xiangrui Meng] update to make generic FPGrowth Java-friendly
737d8bb [Jacky Li] fix scalastyle
793f85c [Jacky Li] add Java test case
7783351 [Jacky Li] add generic support in FPGrowth

1 files changed, 84 insertions, 0 deletions

diff --git a/mllib/src/test/java/org/apache/spark/mllib/fpm/JavaFPGrowthSuite.java b/mllib/src/test/java/org/apache/spark/mllib/fpm/JavaFPGrowthSuite.java
new file mode 100644
index 0000000000..851707c8a1
--- /dev/null
+++ b/mllib/src/test/java/org/apache/spark/mllib/fpm/JavaFPGrowthSuite.java
@@ -0,0 +1,84 @@
+/*
+ * 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
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.mllib.fpm;
+
+import java.io.Serializable;
+import java.util.ArrayList;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import com.google.common.collect.Lists;
+import static org.junit.Assert.*;
+
+import org.apache.spark.api.java.JavaRDD;
+import org.apache.spark.api.java.JavaSparkContext;
+
+public class JavaFPGrowthSuite implements Serializable {
+  private transient JavaSparkContext sc;
+
+  @Before
+  public void setUp() {
+    sc = new JavaSparkContext("local", "JavaFPGrowth");
+  }
+
+  @After
+  public void tearDown() {
+    sc.stop();
+    sc = null;
+  }
+
+  @Test
+  public void runFPGrowth() {
+
+    @SuppressWarnings("unchecked")
+    JavaRDD<ArrayList<String>> rdd = sc.parallelize(Lists.newArrayList(
+      Lists.newArrayList("r z h k p".split(" ")),
+      Lists.newArrayList("z y x w v u t s".split(" ")),
+      Lists.newArrayList("s x o n r".split(" ")),
+      Lists.newArrayList("x z y m t s q e".split(" ")),
+      Lists.newArrayList("z".split(" ")),
+      Lists.newArrayList("x z y r q t p".split(" "))), 2);
+
+    FPGrowth fpg = new FPGrowth();
+
+    FPGrowthModel<String> model6 = fpg
+      .setMinSupport(0.9)
+      .setNumPartitions(1)
+      .run(rdd);
+    assertEquals(0, model6.javaFreqItemsets().count());
+
+    FPGrowthModel<String> model3 = fpg
+      .setMinSupport(0.5)
+      .setNumPartitions(2)
+      .run(rdd);
+    assertEquals(18, model3.javaFreqItemsets().count());
+
+    FPGrowthModel<String> model2 = fpg
+      .setMinSupport(0.3)
+      .setNumPartitions(4)
+      .run(rdd);
+    assertEquals(54, model2.javaFreqItemsets().count());
+
+    FPGrowthModel<String> model1 = fpg
+      .setMinSupport(0.1)
+      .setNumPartitions(8)
+      .run(rdd);
+    assertEquals(625, model1.javaFreqItemsets().count());
+  }
+}