first commit

Author: DB Tsai

mllib/src/main/scala/org/apache/spark/mllib/feature/StandardScaler.scala

@@ -17,11 +17,9 @@
 
 package org.apache.spark.mllib.feature
 
-import breeze.linalg.{DenseVector => BDV, SparseVector => BSV}
-
 import org.apache.spark.Logging
 import org.apache.spark.annotation.Experimental
-import org.apache.spark.mllib.linalg.{Vector, Vectors}
+import org.apache.spark.mllib.linalg.{DenseVector, SparseVector, Vector, Vectors}
 import org.apache.spark.mllib.rdd.RDDFunctions._
 import org.apache.spark.mllib.stat.MultivariateOnlineSummarizer
 import org.apache.spark.rdd.RDD
@@ -77,8 +75,8 @@ class StandardScalerModel private[mllib] (
 
   require(mean.size == variance.size)
 
-  private lazy val factor: BDV[Double] = {
-    val f = BDV.zeros[Double](variance.size)
+  private lazy val factor: Array[Double] = {
+    val f = Array.ofDim[Double](variance.size)
     var i = 0
     while (i < f.size) {
       f(i) = if (variance(i) != 0.0) 1.0 / math.sqrt(variance(i)) else 0.0
@@ -87,6 +85,8 @@ class StandardScalerModel private[mllib] (
     f
   }
 
+  private lazy val shift: Array[Double] = mean.toArray
+
   /**
    * Applies standardization transformation on a vector.
    *
@@ -96,31 +96,48 @@ class StandardScalerModel private[mllib] (
    */
   override def transform(vector: Vector): Vector = {
     require(mean.size == vector.size)
+    val localFactor = factor
     if (withMean) {
-      vector.toBreeze match {
-        case dv: BDV[Double] =>
-          val output = vector.toBreeze.copy
+      val localShift = shift
+      vector match {
+        case dv: DenseVector =>
+          val values = dv.values.clone()
           var i = 0
-          while (i < output.length) {
-            output(i) = (output(i) - mean(i)) * (if (withStd) factor(i) else 1.0)
-            i += 1
+          if(withStd) {
+            while (i < values.length) {
+              values(i) = (values(i) - localShift(i)) * localFactor(i)
+              i += 1
+            }
+          } else {
+            while (i < values.length) {
+              values(i) -= localShift(i)
+              i += 1
+            }
           }
-          Vectors.fromBreeze(output)
+          Vectors.dense(values)
         case v => throw new IllegalArgumentException("Do not support vector type " + v.getClass)
       }
     } else if (withStd) {
-      vector.toBreeze match {
-        case dv: BDV[Double] => Vectors.fromBreeze(dv :* factor)
-        case sv: BSV[Double] =>
+      vector match {
+        case dv: DenseVector =>
+          val values = dv.values.clone()
+          var i = 0
+          while(i < values.length) {
+            values(i) *= localFactor(i)
+            i += 1
+          }
+          Vectors.dense(values)
+        case sv: SparseVector =>
           // For sparse vector, the `index` array inside sparse vector object will not be changed,
           // so we can re-use it to save memory.
-          val output = new BSV[Double](sv.index, sv.data.clone(), sv.length)
+          val indices = sv.indices
+          val values = sv.values.clone()
           var i = 0
-          while (i < output.data.length) {
-            output.data(i) *= factor(output.index(i))
+          while (i < indices.length) {
+            values(i) *= localFactor(indices(i))
             i += 1
           }
-          Vectors.fromBreeze(output)
+          Vectors.sparse(sv.size, indices, values)
         case v => throw new IllegalArgumentException("Do not support vector type " + v.getClass)
       }
     } else {