[SPARK-5879][MLLIB] update PIC user guide and add a Java example

Updated PIC user guide to reflect API changes and added a simple Java example. The API is still not very Java-friendly. I created SPARK-5990 for this issue.

Author: Xiangrui Meng <meng@databricks.com>

Closes #4680 from mengxr/SPARK-5897 and squashes the following commits:

847d216 [Xiangrui Meng] apache header
87719a2 [Xiangrui Meng] remove PIC image
2dd921f [Xiangrui Meng] update PIC user guide and add a Java example

1 files changed, 9 insertions, 0 deletions

diff --git a/mllib/src/main/scala/org/apache/spark/mllib/clustering/PowerIterationClustering.scala b/mllib/src/main/scala/org/apache/spark/mllib/clustering/PowerIterationClustering.scala
index 3b1caf0c67..63d03347f4 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/clustering/PowerIterationClustering.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/clustering/PowerIterationClustering.scala
@@ -17,6 +17,7 @@
 
 package org.apache.spark.mllib.clustering
 
+import org.apache.spark.api.java.JavaRDD
 import org.apache.spark.{Logging, SparkException}
 import org.apache.spark.annotation.Experimental
 import org.apache.spark.graphx._
@@ -116,6 +117,14 @@ class PowerIterationClustering private[clustering] (
   }
 
   /**
+   * A Java-friendly version of [[PowerIterationClustering.run]].
+   */
+  def run(similarities: JavaRDD[(java.lang.Long, java.lang.Long, java.lang.Double)])
+    : PowerIterationClusteringModel = {
+    run(similarities.rdd.asInstanceOf[RDD[(Long, Long, Double)]])
+  }
+
+  /**
    * Runs the PIC algorithm.
    *
    * @param w The normalized affinity matrix, which is the matrix W in the PIC paper with