[MXNET-913] Java API --- Scala NDArray Improvement

scala-package/core/src/main/scala/org/apache/mxnet/NDArray.scala

@@ -248,6 +248,11 @@ object NDArray extends NDArrayBase {
 
   def ones(ctx: Context, shape: Int *): NDArray = ones(Shape(shape: _*), ctx)
 
+  // Java compatible conversion methods
+  def empty(shape: Array[Int]): NDArray = empty(Shape(shape))
+  def zeros(shape: Array[Int]): NDArray = zeros(Shape(shape))
+  def ones(shape: Array[Int]) : NDArray = ones(Shape(shape))
+
   /**
    * Create a new NDArray filled with given value, with specified shape.
    * @param shape shape of the NDArray.
@@ -567,6 +572,18 @@ class NDArray private[mxnet](private[mxnet] val handle: NDArrayHandle,
     NDArrayCollector.collect(this)
   }
 
+  /**
+    * Java Flavor creating new NDArray
+    * @param arr
+    * @param shape
+    * @param ctx
+    * @return
+    */
+  def this(arr : Array[Float], shape : Shape, ctx : Context) = {
+    this(NDArray.newAllocHandle(shape, ctx, delayAlloc = false, Base.MX_REAL_TYPE))
+    this.set(arr)
+  }
+
   // record arrays who construct this array instance
   // we use weak reference to prevent gc blocking
   private[mxnet] val dependencies = mutable.HashMap.empty[Long, WeakReference[NDArray]]
@@ -940,6 +957,44 @@ class NDArray private[mxnet](private[mxnet] val handle: NDArrayHandle,
     this
   }
 
+  /* Java Compatibility Functions
+     Function name with underscore means
+     it is going to do the operator as well as
+     update itself such as +=
+   */
+  def add(other : NDArray) : NDArray = this + other
+  def add(other : Float) : NDArray = this + other
+  def _add(other : NDArray) : NDArray = this += other
+  def _add(other : Float) : NDArray = this += other
+  def subtract(other : NDArray) : NDArray = this - other
+  def subtract(other : Float) : NDArray = this - other
+  def _subtract(other : NDArray) : NDArray = this -= other
+  def _subtract(other : Float) : NDArray = this -= other
+  def multiply(other : NDArray) : NDArray = this * other
+  def multiply(other : Float) : NDArray = this * other
+  def _multiply(other : NDArray) : NDArray = this *= other
+  def _multiply(other : Float) : NDArray = this *= other
+  def div(other : NDArray) : NDArray = this / other
+  def div(other : Float) : NDArray = this / other
+  def _div(other : NDArray) : NDArray = this /= other
+  def _div(other : Float) : NDArray = this /= other
+  def pow(other : NDArray) : NDArray = this ** other
+  def pow(other : Float) : NDArray = this ** other
+  def _pow(other : NDArray) : NDArray = this **= other
+  def _pow(other : Float) : NDArray = this **= other
+  def mod(other : NDArray) : NDArray = this % other
+  def mod(other : Float) : NDArray = this % other
+  def _mod(other : NDArray) : NDArray = this %= other
+  def _mod(other : Float) : NDArray = this %= other
+  def greater(other : NDArray) : NDArray = this > other
+  def greater(other : Float) : NDArray = this > other
+  def greaterEqual(other : NDArray) : NDArray = this >= other
+  def greaterEqual(other : Float) : NDArray = this >= other
+  def lesser(other : NDArray) : NDArray = this < other
+  def lesser(other : Float) : NDArray = this < other
+  def lesserEqual(other : NDArray) : NDArray = this <= other
+  def lesserEqual(other : Float) : NDArray = this <= other
+
   /**
    * Return a copied flat java array of current array (row-major).
    * @return  A copy of array content.

scala-package/core/src/main/scala/org/apache/mxnet/Shape.scala

@@ -29,6 +29,15 @@ class Shape(dims: Traversable[Int]) extends Serializable {
     this(dims.toVector)
   }
 
+  /**
+    * Java compatible constructor
+    * @param dims Array of Int input
+    * @return Shape
+    */
+  def this(dims: Array[Int]) = {
+    this(dims.toVector)
+  }
+
   def apply(dim: Int): Int = shape(dim)
   def get(dim: Int): Int = apply(dim)
   def size: Int = shape.size

scala-package/core/src/main/scala/org/apache/mxnet/api/java/ArgBuilder.scala

@@ -0,0 +1,69 @@
+/*
+ * 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.mxnet.api.java
+
+import scala.collection.mutable
+import scala.collection.mutable.ListBuffer
+import collection.JavaConverters._
+
+/**
+  * This arg Builder is intent to solve Java to Scala conversion
+  * to take the input such as (arg: Any*)
+  */
+class ArgBuilder {
+  private var data = ListBuffer[Any]()
+  private var map = mutable.Map[String, Any]()
+
+  def addArg(anyRef: AnyRef): ArgBuilder = {
+    require(map.isEmpty,
+      "Map is not empty, please do either key-value or positional-arg but not both")
+    this.data += anyRef.asInstanceOf[Any]
+    this
+  }
+
+  def addArg(key : String, value : AnyRef) : ArgBuilder = {
+    require(data.isEmpty,
+      "Data is not empty, please do either key-value or positional-arg but not both")
+    this.map(key) = value.asInstanceOf[Any]
+    this
+  }
+
+  def addBatchArgs(list : java.util.List[AnyRef]) : ArgBuilder = {
+    require(map.isEmpty,
+      "Map is not empty, please do either key-value or positional-arg but not both")
+    for (i <- 0 to list.size()) {
+      this.data += list.get(i)
+    }
+    this
+  }
+
+  def addBatchArgs(arr : Array[AnyRef]) : ArgBuilder = {
+    require(map.isEmpty,
+      "Map is not empty, please do either key-value or positional-arg but not both")
+    arr.foreach(ele => this.data += ele)
+    this
+  }
+
+  def buildMap() : Map[String, Any] = {
+    this.map.toMap
+  }
+
+  def buildSeq() : Seq[Any] = {
+    this.data
+  }
+}

scala-package/core/src/test/scala/org/apache/mxnet/NDArraySuite.scala

@@ -38,6 +38,11 @@ class NDArraySuite extends FunSuite with BeforeAndAfterAll with Matchers {
     assert(ndones.toScalar === 1f)
   }
 
+  test("new NDArray") {
+    val ndarray = new NDArray(Array(1.0f, 2.0f), Shape(1, 2), Context.cpu())
+    assert(ndarray.shape == Shape(1, 2))
+  }
+
   test ("call toScalar on an ndarray which is not a scalar") {
     intercept[Exception] { NDArray.zeros(1, 1).toScalar }
   }