From 737f01a1ef49e4a12f24799c4324b3a60712758e Mon Sep 17 00:00:00 2001
From: Nick Pentreath <nick.pentreath@gmail.com>
Date: Fri, 6 Sep 2013 14:45:05 +0200
Subject: Adding algorithm for implicit feedback data to ALS

---
 .../spark/mllib/recommendation/JavaALSSuite.java   | 77 ++++++++++++++++++----
 1 file changed, 65 insertions(+), 12 deletions(-)

(limited to 'mllib/src/test/java/org')

diff --git a/mllib/src/test/java/org/apache/spark/mllib/recommendation/JavaALSSuite.java b/mllib/src/test/java/org/apache/spark/mllib/recommendation/JavaALSSuite.java
index 3323f6cee2..ec545efcfa 100644
--- a/mllib/src/test/java/org/apache/spark/mllib/recommendation/JavaALSSuite.java
+++ b/mllib/src/test/java/org/apache/spark/mllib/recommendation/JavaALSSuite.java
@@ -19,6 +19,7 @@ package org.apache.spark.mllib.recommendation;
 
 import java.io.Serializable;
 import java.util.List;
+import java.lang.Math;
 
 import scala.Tuple2;
 
@@ -48,7 +49,7 @@ public class JavaALSSuite implements Serializable {
   }
 
   void validatePrediction(MatrixFactorizationModel model, int users, int products, int features, 
-      DoubleMatrix trueRatings, double matchThreshold) {
+      DoubleMatrix trueRatings, double matchThreshold, boolean implicitPrefs, DoubleMatrix truePrefs) {
     DoubleMatrix predictedU = new DoubleMatrix(users, features);
     List<scala.Tuple2<Object, double[]>> userFeatures = model.userFeatures().toJavaRDD().collect();
     for (int i = 0; i < features; ++i) {
@@ -68,12 +69,32 @@ public class JavaALSSuite implements Serializable {
 
     DoubleMatrix predictedRatings = predictedU.mmul(predictedP.transpose());
 
-    for (int u = 0; u < users; ++u) {
-      for (int p = 0; p < products; ++p) {
-        double prediction = predictedRatings.get(u, p);
-        double correct = trueRatings.get(u, p);
-        Assert.assertTrue(Math.abs(prediction - correct) < matchThreshold);
+    if (!implicitPrefs) {
+      for (int u = 0; u < users; ++u) {
+        for (int p = 0; p < products; ++p) {
+          double prediction = predictedRatings.get(u, p);
+          double correct = trueRatings.get(u, p);
+          Assert.assertTrue(String.format("Prediction=%2.4f not below match threshold of %2.2f",
+                  prediction, matchThreshold), Math.abs(prediction - correct) < matchThreshold);
+        }
       }
+    } else {
+      // For implicit prefs we use the confidence-weighted RMSE to test (ref Mahout's implicit ALS tests)
+      double sqErr = 0.0;
+      double denom = 0.0;
+      for (int u = 0; u < users; ++u) {
+        for (int p = 0; p < products; ++p) {
+          double prediction = predictedRatings.get(u, p);
+          double truePref = truePrefs.get(u, p);
+          double confidence = 1.0 + /* alpha = */ 1.0 * trueRatings.get(u, p);
+          double err = confidence * (truePref - prediction) * (truePref - prediction);
+          sqErr += err;
+          denom += 1.0;
+          }
+        }
+      double rmse = Math.sqrt(sqErr / denom);
+      Assert.assertTrue(String.format("Confidence-weighted RMSE=%2.4f above threshold of %2.2f",
+              rmse, matchThreshold), Math.abs(rmse) < matchThreshold);
     }
   }
 
@@ -83,12 +104,12 @@ public class JavaALSSuite implements Serializable {
     int iterations = 15;
     int users = 10;
     int products = 10;
-    scala.Tuple2<List<Rating>, DoubleMatrix> testData = ALSSuite.generateRatingsAsJavaList(
-        users, products, features, 0.7);
+    scala.Tuple3<List<Rating>, DoubleMatrix, DoubleMatrix> testData = ALSSuite.generateRatingsAsJavaList(
+        users, products, features, 0.7, false);
 
     JavaRDD<Rating> data = sc.parallelize(testData._1());
     MatrixFactorizationModel model = ALS.train(data.rdd(), features, iterations);
-    validatePrediction(model, users, products, features, testData._2(), 0.3);
+    validatePrediction(model, users, products, features, testData._2(), 0.3, false, testData._3());
   }
 
   @Test
@@ -97,14 +118,46 @@ public class JavaALSSuite implements Serializable {
     int iterations = 15;
     int users = 20;
     int products = 30;
-    scala.Tuple2<List<Rating>, DoubleMatrix> testData = ALSSuite.generateRatingsAsJavaList(
-        users, products, features, 0.7);
+    scala.Tuple3<List<Rating>, DoubleMatrix, DoubleMatrix> testData = ALSSuite.generateRatingsAsJavaList(
+        users, products, features, 0.7, false);
 
     JavaRDD<Rating> data = sc.parallelize(testData._1());
 
     MatrixFactorizationModel model = new ALS().setRank(features)
                                               .setIterations(iterations)
                                               .run(data.rdd());
-    validatePrediction(model, users, products, features, testData._2(), 0.3);
+    validatePrediction(model, users, products, features, testData._2(), 0.3, false, testData._3());
+  }
+
+  @Test
+  public void runImplicitALSUsingStaticMethods() {
+    int features = 1;
+    int iterations = 15;
+    int users = 40;
+    int products = 80;
+    scala.Tuple3<List<Rating>, DoubleMatrix, DoubleMatrix> testData = ALSSuite.generateRatingsAsJavaList(
+      users, products, features, 0.7, true);
+
+    JavaRDD<Rating> data = sc.parallelize(testData._1());
+    MatrixFactorizationModel model = ALS.trainImplicit(data.rdd(), features, iterations);
+    validatePrediction(model, users, products, features, testData._2(), 0.4, true, testData._3());
+  }
+
+  @Test
+  public void runImplicitALSUsingConstructor() {
+    int features = 2;
+    int iterations = 15;
+    int users = 50;
+    int products = 100;
+    scala.Tuple3<List<Rating>, DoubleMatrix, DoubleMatrix> testData = ALSSuite.generateRatingsAsJavaList(
+      users, products, features, 0.7, true);
+
+    JavaRDD<Rating> data = sc.parallelize(testData._1());
+
+    MatrixFactorizationModel model = new ALS().setRank(features)
+      .setIterations(iterations)
+      .setImplicitPrefs(true)
+      .run(data.rdd());
+    validatePrediction(model, users, products, features, testData._2(), 0.4, true, testData._3());
   }
 }
-- 
cgit v1.2.3