[SPARK-11548][DOCS] Replaced example code in mllib-collaborative-filtering.md using include_example

Kindly review the changes.

Author: Rishabh Bhardwaj <rbnext29@gmail.com>

Closes #9519 from rishabhbhardwaj/SPARK-11337.

1 files changed, 97 insertions, 0 deletions

diff --git a/examples/src/main/java/org/apache/spark/examples/mllib/JavaRecommendationExample.java b/examples/src/main/java/org/apache/spark/examples/mllib/JavaRecommendationExample.java
new file mode 100644
index 0000000000..1065fde953
--- /dev/null
+++ b/examples/src/main/java/org/apache/spark/examples/mllib/JavaRecommendationExample.java
@@ -0,0 +1,97 @@
+/*
+ * 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.examples.mllib;
+
+// $example on$
+import scala.Tuple2;
+
+import org.apache.spark.api.java.*;
+import org.apache.spark.api.java.function.Function;
+import org.apache.spark.mllib.recommendation.ALS;
+import org.apache.spark.mllib.recommendation.MatrixFactorizationModel;
+import org.apache.spark.mllib.recommendation.Rating;
+import org.apache.spark.SparkConf;
+// $example off$
+
+public class JavaRecommendationExample {
+  public static void main(String args[]) {
+    // $example on$
+    SparkConf conf = new SparkConf().setAppName("Java Collaborative Filtering Example");
+    JavaSparkContext jsc = new JavaSparkContext(conf);
+
+    // Load and parse the data
+    String path = "data/mllib/als/test.data";
+    JavaRDD<String> data = jsc.textFile(path);
+    JavaRDD<Rating> ratings = data.map(
+      new Function<String, Rating>() {
+        public Rating call(String s) {
+          String[] sarray = s.split(",");
+          return new Rating(Integer.parseInt(sarray[0]), Integer.parseInt(sarray[1]),
+            Double.parseDouble(sarray[2]));
+        }
+      }
+    );
+
+    // Build the recommendation model using ALS
+    int rank = 10;
+    int numIterations = 10;
+    MatrixFactorizationModel model = ALS.train(JavaRDD.toRDD(ratings), rank, numIterations, 0.01);
+
+    // Evaluate the model on rating data
+    JavaRDD<Tuple2<Object, Object>> userProducts = ratings.map(
+      new Function<Rating, Tuple2<Object, Object>>() {
+        public Tuple2<Object, Object> call(Rating r) {
+          return new Tuple2<Object, Object>(r.user(), r.product());
+        }
+      }
+    );
+    JavaPairRDD<Tuple2<Integer, Integer>, Double> predictions = JavaPairRDD.fromJavaRDD(
+      model.predict(JavaRDD.toRDD(userProducts)).toJavaRDD().map(
+        new Function<Rating, Tuple2<Tuple2<Integer, Integer>, Double>>() {
+          public Tuple2<Tuple2<Integer, Integer>, Double> call(Rating r){
+            return new Tuple2<Tuple2<Integer, Integer>, Double>(
+              new Tuple2<Integer, Integer>(r.user(), r.product()), r.rating());
+          }
+        }
+      ));
+    JavaRDD<Tuple2<Double, Double>> ratesAndPreds =
+      JavaPairRDD.fromJavaRDD(ratings.map(
+        new Function<Rating, Tuple2<Tuple2<Integer, Integer>, Double>>() {
+          public Tuple2<Tuple2<Integer, Integer>, Double> call(Rating r){
+            return new Tuple2<Tuple2<Integer, Integer>, Double>(
+              new Tuple2<Integer, Integer>(r.user(), r.product()), r.rating());
+          }
+        }
+      )).join(predictions).values();
+    double MSE = JavaDoubleRDD.fromRDD(ratesAndPreds.map(
+      new Function<Tuple2<Double, Double>, Object>() {
+        public Object call(Tuple2<Double, Double> pair) {
+          Double err = pair._1() - pair._2();
+          return err * err;
+        }
+      }
+    ).rdd()).mean();
+    System.out.println("Mean Squared Error = " + MSE);
+
+    // Save and load model
+    model.save(jsc.sc(), "target/tmp/myCollaborativeFilter");
+    MatrixFactorizationModel sameModel = MatrixFactorizationModel.load(jsc.sc(),
+      "target/tmp/myCollaborativeFilter");
+    // $example off$
+  }
+}