[SPARK-19759][ML] not using blas in ALSModel.predict for optimization

apache · Nov 7, 2017 · 8b0add6 · 8b0add6
1 parent 4bacddb
commit 8b0add6
Showing 1 changed file with 5 additions and 3 deletions.
diff --git a/mllib/src/main/scala/org/apache/spark/ml/recommendation/ALS.scala b/mllib/src/main/scala/org/apache/spark/ml/recommendation/ALS.scala
@@ -289,9 +289,11 @@ class ALSModel private[ml] (
 
   private val predict = udf { (featuresA: Seq[Float], featuresB: Seq[Float]) =>
     if (featuresA != null && featuresB != null) {
-      // TODO(SPARK-19759): try dot-producting on Seqs or another non-converted type for
-      // potential optimization.
-      blas.sdot(rank, featuresA.toArray, 1, featuresB.toArray, 1)
+      var dotProduct = 0.0f
+      for(i <- 0 until rank) {
+        dotProduct += featuresA(i) * featuresB(i)
+      }
+      dotProduct
     } else {
       Float.NaN
     }