Merge pull request #4 from terrytangyuan/terry

Additional implementation and test cases

scala-package/core/src/main/scala/ml/dmlc/mxnet/NDArray.scala

@@ -217,15 +217,19 @@ object NDArray {
    * @param ctx The context of the NDArray, default to current default context.
    * @return The created NDArray.
    */
-  def ones(shape: Array[Int], ctx: Context=null): NDArray = ???
+  def ones(shape: Array[Int], ctx: Context=null): NDArray = {
+    val arr = empty(shape, ctx)
+    arr(0).set(1f)
+    arr
+  }
 
   /**
    * Create a new NDArray that copies content from source_array.
-   * @param source Source data to create NDArray from.
+   * @param sourceArr Source data to create NDArray from.
    * @param ctx The context of the NDArray, default to current default context.
    * @return The created NDArray.
    */
-  def array(source: Array[Float], ctx: Context=null): NDArray = ???
+  def array(sourceArr: Array[Int], ctx: Context=null): NDArray = ???
 
   /**
    * Load ndarray from binary file.
@@ -326,7 +330,9 @@ class NDArray(val handle: NDArrayHandle, val writable: Boolean = true) {
     this
   }
 
-  def set(other: NDArray) = ???
+  def set(other: NDArray) = {
+    other.copyTo(this)
+  }
 
   def +(other: NDArray): NDArray = {
     NDArray._binaryNDArrayFunction("_plus", this, other)
@@ -441,7 +447,12 @@ class NDArray(val handle: NDArrayHandle, val writable: Boolean = true) {
    *
    * @return The scalar representation of the ndarray.
    */
-  def toScalar: Float = ???
+  def toScalar: Float = {
+    if (this.size != 1) {
+      throw new IllegalArgumentException("The current array is not a scalar")
+    }
+    this.toArray(0)
+  }
 
   /**
    * Copy the content of current array to other.

scala-package/core/src/test/scala/ml/dmlc/mxnet/NDArraySuite.scala

@@ -9,6 +9,19 @@ class NDArraySuite extends FunSuite with BeforeAndAfterAll {
     assert(ndarray.toArray === Array(0f, 0f, 0f, 0f))
   }
 
+  test("to scalar") {
+    val ndzeros = NDArray.zeros(Array(1, 1))
+    assert(ndzeros.toScalar === 0f)
+    val ndones = NDArray.ones(Array(1, 1))
+    assert(ndones.toScalar === 1f)
+  }
+
+  test("size and shape") {
+    val ndzeros = NDArray.zeros(Array(4, 1))
+    assert(ndzeros.shape === Array(4, 1))
+    assert(ndzeros.size === 4)
+  }
+
   test("plus") {
     val ndzeros = NDArray.zeros(Array(2, 1))
     val ndones = ndzeros + 1f
@@ -19,4 +32,41 @@ class NDArraySuite extends FunSuite with BeforeAndAfterAll {
     ndones += ndones
     assert(ndones.toArray === Array(2f, 2f))
   }
+
+  test("minus") {
+    val ndones = NDArray.ones(Array(2, 1))
+    val ndzeros = ndones - 1f
+    assert(ndzeros.toArray === Array(0f, 0f))
+    assert((ndones - ndzeros).toArray === Array(1f, 1f))
+    assert((ndzeros - ndones).toArray === Array(-1f, -1f))
+    assert((ndones - 1).toArray === Array(0f, 0f))
+    // in-place
+    ndones -= ndones
+    assert(ndones.toArray === Array(0f, 0f))
+  }
+
+  test("multiplication") {
+    val ndones = NDArray.ones(Array(2, 1))
+    val ndtwos = ndones * 2
+    assert(ndtwos.toArray === Array(2f, 2f))
+    assert((ndones * ndones).toArray === Array(1f, 1f))
+    assert((ndtwos * ndtwos).toArray === Array(4f, 4f))
+    ndtwos *= ndtwos
+    // in-place
+    assert(ndtwos.toArray === Array(4f, 4f))
+  }
+
+  test("division") {
+    val ndones = NDArray.ones(Array(2, 1))
+    val ndzeros = ndones - 1f
+    val ndhalves = ndones / 2
+    assert(ndhalves.toArray === Array(0.5f, 0.5f))
+    assert((ndhalves / ndhalves).toArray === Array(1f, 1f))
+    assert((ndones / ndones).toArray === Array(1f, 1f))
+    assert((ndzeros / ndones).toArray === Array(0f, 0f))
+    ndhalves /= ndhalves
+    // in-place
+    assert(ndhalves.toArray === Array(1f, 1f))
+  }
+
 }