[SPARK-9750] [MLLIB] Improve equals on SparseMatrix and DenseMatrix

Adds unit test for `equals` on `mllib.linalg.Matrix` class and `equals` to both `SparseMatrix` and `DenseMatrix`. Supports equality testing between `SparseMatrix` and `DenseMatrix`.

mengxr

Author: Feynman Liang <fliang@databricks.com>

Closes #8042 from feynmanliang/SPARK-9750 and squashes the following commits:

bb70d5e [Feynman Liang] Breeze compare for dense matrices as well, in case other is sparse
ab6f3c8 [Feynman Liang] Sparse matrix compare for equals
22782df [Feynman Liang] Add equality based on matrix semantics, not representation
78f9426 [Feynman Liang] Add casts
43d28fa [Feynman Liang] Fix failing test
6416fa0 [Feynman Liang] Add failing sparse matrix equals tests

1 files changed, 6 insertions, 2 deletions

diff --git a/mllib/src/main/scala/org/apache/spark/mllib/linalg/Matrices.scala b/mllib/src/main/scala/org/apache/spark/mllib/linalg/Matrices.scala
index 1c858348bf..1139ce36d5 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/linalg/Matrices.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/linalg/Matrices.scala
@@ -257,8 +257,7 @@ class DenseMatrix(
     this(numRows, numCols, values, false)
 
   override def equals(o: Any): Boolean = o match {
-    case m: DenseMatrix =>
-      m.numRows == numRows && m.numCols == numCols && Arrays.equals(toArray, m.toArray)
+    case m: Matrix => toBreeze == m.toBreeze
     case _ => false
   }
 
@@ -519,6 +518,11 @@ class SparseMatrix(
       rowIndices: Array[Int],
       values: Array[Double]) = this(numRows, numCols, colPtrs, rowIndices, values, false)
 
+  override def equals(o: Any): Boolean = o match {
+    case m: Matrix => toBreeze == m.toBreeze
+    case _ => false
+  }
+
   private[mllib] def toBreeze: BM[Double] = {
      if (!isTransposed) {
        new BSM[Double](values, numRows, numCols, colPtrs, rowIndices)