Refactor GLM algorithms and add Java tests

This change adds Java examples and unit tests for all GLM algorithms
to make sure the MLLib interface works from Java. Changes include
- Introduce LabeledPoint and avoid using Doubles in train arguments
- Rename train to run in class methods
- Make the optimizer a member variable of GLM to make sure the builder
  pattern works

1 files changed, 85 insertions, 0 deletions

diff --git a/examples/src/main/java/spark/mllib/examples/JavaLR.java b/examples/src/main/java/spark/mllib/examples/JavaLR.java
new file mode 100644
index 0000000000..e11f4830a8
--- /dev/null
+++ b/examples/src/main/java/spark/mllib/examples/JavaLR.java
@@ -0,0 +1,85 @@
+/*
+ * 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 spark.mllib.examples;
+
+
+import spark.api.java.JavaRDD;
+import spark.api.java.JavaSparkContext;
+import spark.api.java.function.Function;
+
+import spark.mllib.classification.LogisticRegressionWithSGD;
+import spark.mllib.classification.LogisticRegressionModel;
+import spark.mllib.regression.LabeledPoint;
+
+import java.util.Arrays;
+import java.util.StringTokenizer;
+
+/**
+ * Logistic regression based classification using ML Lib.
+ */
+public class JavaLR {
+
+  static class ParsePoint extends Function<String, LabeledPoint> {
+    public LabeledPoint call(String line) {
+      String[] parts = line.split(",");
+      Double y = Double.parseDouble(parts[0]);
+      StringTokenizer tok = new StringTokenizer(parts[1], " ");
+      int numTokens = tok.countTokens();
+      double[] x = new double[numTokens];
+      for (int i = 0; i < numTokens; ++i) {
+        x[i] = Double.parseDouble(tok.nextToken());
+      }
+      return new LabeledPoint(y, x);
+    }
+  }
+
+  public static void printWeights(double[] a) {
+    System.out.println(Arrays.toString(a));
+  }
+
+  public static void main(String[] args) {
+    if (args.length != 4) {
+      System.err.println("Usage: JavaLR <master> <input_dir> <step_size> <niters>");
+      System.exit(1);
+    }
+
+    JavaSparkContext sc = new JavaSparkContext(args[0], "JavaLR",
+        System.getenv("SPARK_HOME"), System.getenv("SPARK_EXAMPLES_JAR"));
+    JavaRDD<String> lines = sc.textFile(args[1]);
+    JavaRDD<LabeledPoint> points = lines.map(new ParsePoint()).cache();
+    double stepSize = Double.parseDouble(args[2]);
+    int iterations = Integer.parseInt(args[3]);
+
+    // Another way to configure LogisticRegression
+    //
+    // LogisticRegressionWithSGD lr = new LogisticRegressionWithSGD();
+    // lr.optimizer().setNumIterations(iterations)
+    //               .setStepSize(stepSize)
+    //               .setMiniBatchFraction(1.0);
+    // lr.setIntercept(true);
+    // LogisticRegressionModel model = lr.train(points.rdd());
+
+    LogisticRegressionModel model = LogisticRegressionWithSGD.train(points.rdd(),
+        iterations, stepSize);
+
+    System.out.print("Final w: ");
+    printWeights(model.weights());
+
+    System.exit(0);
+  }
+}