update impl

Author: mengxr

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

@@ -67,21 +67,23 @@ sealed trait Vector extends Serializable {
     }
   }
 
+  /**
+   * Returns a hash code value for the vector. The hash code is based on its size and its nonzeros
+   * in the first 16 entries, using a hash algorithm similar to [[java.util.Arrays.hashCode]].
+   */
   override def hashCode(): Int = {
-    var result: Int = size + 31
-    var i = 0
-    this.foreachActive { case (index, value) =>
-      // ignore explict 0 for comparison between sparse and dense
-      if (value != 0) {
-        result = 31 * result + index
-        // refer to {@link java.util.Arrays.equals} for hash algorithm
-        val bits = java.lang.Double.doubleToLongBits(value)
-        result = 31 * result + (bits ^ (bits >>> 32)).toInt
-        i += 1
-        // only scan the first 16 nonzeros
-        if (i > 16) {
-          return result
+    // This is a reference implementation. It calls return in foreachActive, which is slow.
+    var result: Int = 31 + size
+    this.foreachActive { (index, value) =>
+      if (index < 16) {
+        // ignore explict 0 for comparison between sparse and dense
+        if (value != 0) {
+          result = 31 * result + index
+          val bits = java.lang.Double.doubleToLongBits(value)
+          result = 31 * result + (bits ^ (bits >>> 32)).toInt
         }
+      } else {
+        return result
       }
     }
     result
@@ -322,7 +324,7 @@ object Vectors {
       case SparseVector(n, ids, vs) => vs
       case v => throw new IllegalArgumentException("Do not support vector type " + v.getClass)
     }
-    val size = values.size
+    val size = values.length
 
     if (p == 1) {
       var sum = 0.0
@@ -376,8 +378,8 @@ object Vectors {
         val v1Indices = v1.indices
         val v2Values = v2.values
         val v2Indices = v2.indices
-        val nnzv1 = v1Indices.size
-        val nnzv2 = v2Indices.size
+        val nnzv1 = v1Indices.length
+        val nnzv2 = v2Indices.length
 
         var kv1 = 0
         var kv2 = 0
@@ -406,7 +408,7 @@ object Vectors {
 
       case (DenseVector(vv1), DenseVector(vv2)) =>
         var kv = 0
-        val sz = vv1.size
+        val sz = vv1.length
         while (kv < sz) {
           val score = vv1(kv) - vv2(kv)
           squaredDistance += score * score
@@ -427,7 +429,7 @@ object Vectors {
     var kv2 = 0
     val indices = v1.indices
     var squaredDistance = 0.0
-    val nnzv1 = indices.size
+    val nnzv1 = indices.length
     val nnzv2 = v2.size
     var iv1 = if (nnzv1 > 0) indices(kv1) else -1
 
@@ -456,8 +458,8 @@ object Vectors {
       v1Values: Array[Double],
       v2Indices: IndexedSeq[Int],
       v2Values: Array[Double]): Boolean = {
-    val v1Size = v1Values.size
-    val v2Size = v2Values.size
+    val v1Size = v1Values.length
+    val v2Size = v2Values.length
     var k1 = 0
     var k2 = 0
     var allEqual = true
@@ -498,14 +500,30 @@ class DenseVector(val values: Array[Double]) extends Vector {
 
   private[spark] override def foreachActive(f: (Int, Double) => Unit) = {
     var i = 0
-    val localValuesSize = values.size
+    val localValuesSize = values.length
     val localValues = values
 
     while (i < localValuesSize) {
       f(i, localValues(i))
       i += 1
     }
   }
+
+  override def hashCode(): Int = {
+    var result: Int = 31 + size
+    var i = 0
+    val end = math.min(values.length, 16)
+    while (i < end) {
+      val v = values(i)
+      if (v != 0.0) {
+        result = 31 * result + i
+        val bits = java.lang.Double.doubleToLongBits(values(i))
+        result = 31 * result + (bits ^ (bits >>> 32)).toInt
+      }
+      i += 1
+    }
+    result
+  }
 }
 
 object DenseVector {
@@ -527,8 +545,8 @@ class SparseVector(
     val values: Array[Double]) extends Vector {
 
   require(indices.length == values.length, "Sparse vectors require that the dimension of the" +
-    s" indices match the dimension of the values. You provided ${indices.size} indices and " +
-    s" ${values.size} values.")
+    s" indices match the dimension of the values. You provided ${indices.length} indices and " +
+    s" ${values.length} values.")
 
   override def toString: String =
     "(%s,%s,%s)".format(size, indices.mkString("[", ",", "]"), values.mkString("[", ",", "]"))
@@ -552,7 +570,7 @@ class SparseVector(
 
   private[spark] override def foreachActive(f: (Int, Double) => Unit) = {
     var i = 0
-    val localValuesSize = values.size
+    val localValuesSize = values.length
     val localIndices = indices
     val localValues = values
 
@@ -561,6 +579,28 @@ class SparseVector(
       i += 1
     }
   }
+
+  override def hashCode(): Int = {
+    var result: Int = 31 + size
+    val end = values.length
+    var continue = true
+    var k = 0
+    while ((k < end) & continue) {
+      val i = indices(k)
+      if (i < 16) {
+        val v = values(k)
+        if (v != 0.0) {
+          result = 31 * result + i
+          val bits = java.lang.Double.doubleToLongBits(v)
+          result = 31 * result + (bits ^ (bits >>> 32)).toInt
+        }
+      } else {
+        continue = false
+      }
+      k += 1
+    }
+    result
+  }
 }
 
 object SparseVector {