Merge pull request #369 from pillis/master

SPARK-961 Add a Vector.random() method

Added method and testcases

core/src/main/scala/org/apache/spark/util/Vector.scala

@@ -17,6 +17,8 @@
 
 package org.apache.spark.util
 
+import scala.util.Random
+
 class Vector(val elements: Array[Double]) extends Serializable {
   def length = elements.length
 
@@ -124,6 +126,12 @@ object Vector {
 
   def ones(length: Int) = Vector(length, _ => 1)
 
+  /**
+   * Creates this [[org.apache.spark.util.Vector]] of given length containing random numbers 
+   * between 0.0 and 1.0. Optional [[scala.util.Random]] number generator can be provided.
+   */
+  def random(length: Int, random: Random = new XORShiftRandom()) = Vector(length, _ => random.nextDouble())
+
   class Multiplier(num: Double) {
     def * (vec: Vector) = vec * num
   }

core/src/test/scala/org/apache/spark/util/VectorSuite.scala

@@ -0,0 +1,44 @@
+/*
+ * 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.util
+
+import scala.util.Random
+
+import org.scalatest.FunSuite
+
+/**
+ * Tests org.apache.spark.util.Vector functionality
+ */
+class VectorSuite extends FunSuite {
+
+  def verifyVector(vector: Vector, expectedLength: Int) = {
+    assert(vector.length == expectedLength)
+    assert(vector.elements.min > 0.0)
+    assert(vector.elements.max < 1.0)
+  }
+
+  test("random with default random number generator") {
+    val vector100 = Vector.random(100)
+    verifyVector(vector100, 100)
+  }
+
+  test("random with given random number generator") {
+    val vector100 = Vector.random(100, new Random(100))
+    verifyVector(vector100, 100)
+  }
+}