Movie recommender

pom.xml

@@ -12,6 +12,8 @@
 
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <maven.compiler.source>11</maven.compiler.source>
+    <maven.compiler.target>11</maven.compiler.target>
   </properties>
 
   <dependencies>
@@ -26,5 +28,15 @@
           <version>4.7</version>
           <scope>test</scope>
       </dependency>
+      <dependency>
+        <groupId>org.slf4j</groupId>
+        <artifactId>slf4j-api</artifactId>
+        <version>1.7.32</version>
+    </dependency>
+    <dependency>
+        <groupId>org.slf4j</groupId>
+        <artifactId>slf4j-simple</artifactId>
+        <version>1.7.5</version>
+    </dependency>
   </dependencies>
 </project>

src/main/java/nearsoft/academy/MovieRecommender.java

@@ -0,0 +1,149 @@
+package nearsoft.academy;
+
+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.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+import java.util.zip.GZIPInputStream;
+
+import org.apache.commons.collections.BidiMap;
+import org.apache.commons.collections.bidimap.DualHashBidiMap;
+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.UserBasedRecommender;
+import org.apache.mahout.cf.taste.similarity.UserSimilarity;
+
+
+public class MovieRecommender {
+    private static String ROOT_PATH = System.getProperty("user.dir");
+    private static String CSV_DATA_PATH = ROOT_PATH + "/src/main/resources/data.csv";
+
+    private String dataFilePath;
+
+    private BidiMap products = new DualHashBidiMap();
+    private Map<String, Integer> users = new HashMap<String, Integer>();
+
+    private int totalUsers = 0;
+    private int totalProducts = 0;
+    private int totalReviews = 0;
+
+    private DataModel model;
+    private UserSimilarity similarity;
+    private UserNeighborhood neighborhood;
+    private UserBasedRecommender recommender;
+
+    public MovieRecommender(String dataFilePath) throws IOException, TasteException {
+        this.dataFilePath = dataFilePath;
+
+        File processedData = new File(CSV_DATA_PATH);
+
+        try {
+            if (processedData.exists()) { processedData.delete(); }
+            processFile();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+        this.model = new FileDataModel(new File(CSV_DATA_PATH));
+        this.similarity = new PearsonCorrelationSimilarity(this.model);
+        this.neighborhood = new ThresholdUserNeighborhood(0.1, this.similarity, this.model);
+        this.recommender = new GenericUserBasedRecommender(this.model, this.neighborhood, this.similarity);
+    }
+
+    private void processFile () throws IOException {
+        FileInputStream file = new FileInputStream(this.dataFilePath);
+        GZIPInputStream gzip = new GZIPInputStream(file);
+        InputStreamReader isr = new InputStreamReader(gzip);
+        BufferedReader br = new BufferedReader(isr);
+
+        List<String> dataParts = new ArrayList<String>();
+        String line;
+
+        FileWriter fileWriter = new FileWriter(CSV_DATA_PATH);
+
+        while ((line = br.readLine()) != null) {
+            String[] elements = {"product/productId:", "review/userId:", "review/score:"};
+
+            String[] parts = line.split(" ");
+
+            Boolean idRequiredField = Arrays.asList(elements).contains(parts[0]);
+
+            if (idRequiredField) {
+                dataParts.add(parts[1]);
+            }
+
+            if (dataParts.size() == 3) {
+                String userId = dataParts.get(1);
+                String productId = dataParts.get(0);
+                String score = dataParts.get(2);
+
+                int productIdxVal = (this.products.containsKey(productId) ? (int) this.products.get(productId) : totalProducts);
+                int userIdxVal = (this.users.containsKey(userId) ? this.users.get(userId) : totalUsers);
+
+                String mixedData = userIdxVal + "," + productIdxVal + "," + score + "\n";
+                fileWriter.write(mixedData);
+
+                this.setOccurrences(productId, userId);
+
+                dataParts = new ArrayList<String>();
+            }
+        }
+
+        fileWriter.close();
+        br.close();
+    }
+
+    private void setOccurrences (String productId, String userId) {
+        // Count reviews
+        this.totalReviews++;
+
+        // Count products
+        if (!this.products.containsKey(productId)) {
+            this.products.put(productId, totalProducts);
+            this.totalProducts++;
+        }
+
+        // Count users
+        if (!this.users.containsKey(userId)) {
+            this.users.put(userId, totalUsers);
+            this.totalUsers++;
+        }
+    }
+
+    public int getTotalReviews() {
+        return this.totalReviews;
+    }
+
+    public int getTotalProducts () {
+        return this.totalProducts;
+    }
+
+    public int getTotalUsers () {
+        return this.totalUsers;
+    }
+
+    public List<String> getRecommendationsForUser (String userID) throws TasteException {
+        List<String> recommendations = new ArrayList<String>();
+
+        recommendations = recommender.recommend(users.get(userID), 3)
+            .stream()
+            .map(item -> (String) products.getKey((int) item.getItemID()))
+            .collect(Collectors.toList()
+        );
+
+        return recommendations;
+    }
+}

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

@@ -3,6 +3,8 @@
 import org.apache.mahout.cf.taste.common.TasteException;
 import org.junit.Test;
 
+import nearsoft.academy.MovieRecommender;
+
 import java.io.IOException;
 import java.util.List;
 
@@ -13,9 +15,10 @@
 public class MovieRecommenderTest {
     @Test
     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");
+
+        String ROOT_PATH = System.getProperty("user.dir");
+
+        MovieRecommender recommender = new MovieRecommender(ROOT_PATH + "/src/main/resources/movies.txt.gz");
         assertEquals(7911684, recommender.getTotalReviews());
         assertEquals(253059, recommender.getTotalProducts());
         assertEquals(889176, recommender.getTotalUsers());
@@ -26,5 +29,4 @@ public void testDataInfo() throws IOException, TasteException {
         assertThat(recommendations, hasItem("B000063W82"));
 
     }
-
 }