Add MovieRecommender Class

.gitignore

@@ -0,0 +1,147 @@
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src/test/java/nearsoft/academy/bigdata/recommendation/MovieRecommender.java

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+package nearsoft.academy.bigdata.recommendation;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.util.ArrayList;
+import java.util.Hashtable;
+import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import java.util.zip.GZIPInputStream;
+
+import org.apache.mahout.cf.taste.common.TasteException;
+import org.apache.mahout.cf.taste.impl.model.file.FileDataModel;
+import org.apache.mahout.cf.taste.impl.neighborhood.ThresholdUserNeighborhood;
+import org.apache.mahout.cf.taste.impl.recommender.GenericUserBasedRecommender;
+import org.apache.mahout.cf.taste.impl.similarity.PearsonCorrelationSimilarity;
+import org.apache.mahout.cf.taste.model.DataModel;
+import org.apache.mahout.cf.taste.neighborhood.UserNeighborhood;
+import org.apache.mahout.cf.taste.recommender.RecommendedItem;
+import org.apache.mahout.cf.taste.recommender.UserBasedRecommender;
+import org.apache.mahout.cf.taste.similarity.UserSimilarity;
+
+class MovieRecommender {
+    String filePath;
+    int totalUsers;
+    int totalReviews;
+    int totalProducts;
+    Hashtable<String, Integer> users;
+    Hashtable<String, Integer> products;
+    Hashtable<Integer, String> productsById;
+
+    MovieRecommender(String fileUrl) throws IOException {
+        this.filePath = fileUrl;
+        this.totalUsers = 0;
+        this.totalReviews = 0;
+        this.totalProducts = 0;
+        this.users = new Hashtable<String, Integer>();
+        this.products = new Hashtable<String, Integer>();
+        this.productsById = new Hashtable<Integer, String>();
+
+        processFile();
+    }
+
+    public void processFile() throws IOException {
+        FileInputStream file = new FileInputStream(this.filePath);
+        GZIPInputStream gzipInput = new GZIPInputStream(file);
+        Reader decoder = new InputStreamReader(gzipInput);
+        BufferedReader reader = new BufferedReader(decoder);
+
+        Pattern usersRegex = Pattern.compile("review\\/userId: ([\\D\\d]+)");
+        Pattern reviewsRegex = Pattern.compile("review\\/score: ([\\D\\d]+)");
+        Pattern productsRegex = Pattern.compile("product\\/productId: ([\\D\\d]+)");
+
+        Matcher match;
+        boolean matches;
+
+        String currentLine = reader.readLine();
+
+        FileWriter writer = new FileWriter("movies.csv");
+
+        String userId = "";
+        String reviewId = "";
+        String productId = "";
+
+        while (currentLine != null) {
+
+            match = usersRegex.matcher(currentLine);
+            matches = match.matches();
+
+            if (matches) {
+                userId = currentLine.split(" ")[1];
+
+                if (users.get(userId) == null) {
+                    this.totalUsers++;
+                    users.put(userId, this.totalUsers);
+                }
+            }
+
+            match = reviewsRegex.matcher(currentLine);
+            matches = match.matches();
+
+            if (matches) {
+                reviewId = currentLine.split(" ")[1];
+                this.totalReviews++;
+            }
+
+            match = productsRegex.matcher(currentLine);
+            matches = match.matches();
+
+            if (matches) {
+                productId = currentLine.split(" ")[1];
+
+                if (products.get(productId) == null) {
+                    this.totalProducts++;
+                    products.put(productId, this.totalProducts);
+                    productsById.put(this.totalProducts, productId);
+                }
+            }
+
+            if (userId != "" && reviewId != "" && productId != "") {
+                writer.write(users.get(userId) + "," + products.get(productId) + "," + reviewId + "\n");
+                userId = "";
+                reviewId = "";
+                productId = "";
+            }
+
+            currentLine = reader.readLine();
+        }
+
+        reader.close();
+        writer.close();
+    }
+
+    public int getTotalUsers() { return this.totalUsers; }
+
+    public int getTotalReviews() { return this.totalReviews; }
+
+    public int getTotalProducts() { return this.totalProducts; }
+
+    public List<String> getRecommendationsForUser(String userId) throws IOException, TasteException {
+        DataModel model = new FileDataModel(new File("movies.csv"));
+        UserSimilarity similarity = new PearsonCorrelationSimilarity(model);
+        UserNeighborhood neighborhood = new ThresholdUserNeighborhood(0.1, similarity, model);
+        UserBasedRecommender recommender = new GenericUserBasedRecommender(model, neighborhood, similarity);
+
+        List<String> recommendations = new ArrayList<String>();
+
+        for (RecommendedItem recommendation : recommender.recommend(users.get(userId), 3)) {
+            recommendations.add(productsById.get((int)(recommendation.getItemID())));
+        }
+
+        return recommendations;
+    }
+}

src/test/java/nearsoft/academy/bigdata/recommendation/MovieRecommenderTest.java

@@ -15,7 +15,7 @@ public class MovieRecommenderTest {
     public void testDataInfo() throws IOException, TasteException {
         //download movies.txt.gz from 
         //    http://snap.stanford.edu/data/web-Movies.html
-        MovieRecommender recommender = new MovieRecommender("/path/to/movies.txt.gz");
+        MovieRecommender recommender = new MovieRecommender("movies.txt.gz");
         assertEquals(7911684, recommender.getTotalReviews());
         assertEquals(253059, recommender.getTotalProducts());
         assertEquals(889176, recommender.getTotalUsers());