iterative equals for sparse vector

Author: hhbyyh

mllib/src/main/scala/org/apache/spark/mllib/linalg/Vectors.scala

@@ -451,10 +451,25 @@ class SparseVector(
 
   override def equals(other: Any): Boolean = {
     other match {
-      case v: SparseVector =>
-        this.size == v.size &&
-          util.Arrays.equals(this.indices, v.indices) &&
-          util.Arrays.equals(this.values, v.values)
+      case v: SparseVector => {
+        if (this.size != v.size) { return false }
+        var k1 = 0
+        var k2 = 0
+        while (true) {
+          while (k1 < this.values.size && this.values(k1) == 0) k1 += 1
+          while (k2 < v.values.size && v.values(k2) == 0) k2 += 1
+
+          if (k1 == this.values.size || k2 == v.values.size) {
+            return (k1 == this.values.size && k2 == v.values.size) //check end alignment
+          }
+          if (this.indices(k1) != v.indices(k2) || this.values(k1) != v.values(k2)) {
+            return false
+          }
+          k1 += 1
+          k2 += 1
+        }
+        throw new Exception("unreachable")
+      }
       case _ => super.equals(other)
     }
   }

mllib/src/test/scala/org/apache/spark/mllib/linalg/VectorsSuite.scala

@@ -89,6 +89,29 @@ class VectorsSuite extends FunSuite {
     }
   }
 
+  test("sparse equals with explicit 0") {
+    val sv1 = Vectors.sparse(10, Array(1, 3, 4, 7), Array(0.9, 0.8, 0.7, 0.6))
+    val sv2 = Vectors.sparse(10, Array(0, 1, 3, 4, 7), Array(0.0, 0.9, 0.8, 0.7, 0.6))
+    val sv3 = Vectors.sparse(10, Array(1, 3, 4, 5, 6, 7), Array(0.9, 0.8, 0, 0, 0.7, 0.6))
+    val sv4 = Vectors.sparse(10, Array(1, 3, 4, 7, 9), Array(0.9, 0.8, 0.7, 0.6, 0))
+    val sv5 = Vectors.sparse(10, Array(0, 1, 2, 3, 4, 5, 6, 7, 8, 9),
+      Array(0, 0.9, 0, 0.8, 0.7, 0, 0, 0.6, 0, 0))
+
+    val vectors = Seq(sv1, sv2, sv3, sv4, sv5)
+
+    for (v <- vectors; u <- vectors) {
+      assert(v === u)
+      assert(v.## === u.##)
+    }
+
+    val another = Vectors.sparse(10, Array(1, 3, 4, 7), Array(0.9, 0.2, 0.7, 0.6))
+
+    for (v <- vectors) {
+      assert(v != another)
+      assert(v.## != another.##)
+    }
+  }
+
   test("indexing dense vectors") {
     val vec = Vectors.dense(1.0, 2.0, 3.0, 4.0)
     assert(vec(0) === 1.0)