Github user dbtsai commented on a diff in the pull request:
https://github.com/apache/spark/pull/3288#discussion_r20687461
--- Diff:
mllib/src/main/scala/org/apache/spark/mllib/stat/MultivariateOnlineSummarizer.scala
---
@@ -95,22 +93,7 @@ class MultivariateOnlineSummarizer extends
MultivariateStatisticalSummary with S
require(n == sample.size, s"Dimensions mismatch when adding new
sample." +
s" Expecting $n but got ${sample.size}.")
- sample match {
- case dv: DenseVector => {
- var j = 0
- while (j < dv.size) {
- add(j, dv.values(j))
- j += 1
- }
- }
- case sv: SparseVector =>
- var j = 0
- while (j < sv.indices.size) {
- add(sv.indices(j), sv.values(j))
- j += 1
- }
- case v => throw new IllegalArgumentException("Do not support vector
type " + v.getClass)
- }
+ sample.foreach(true)(x => add(x._1, x._2))
--- End diff --
This will be faster than
```scala
sample.foreach(true){
case (index, value) => add(index, value)
}
```
for 5%.
See the generated bytecode.
With pattern matching.
```
L20
LINENUMBER 103 L20
ALOAD 4
INVOKEVIRTUAL scala/Tuple2._1$mcI$sp ()I
ISTORE 5
L21
ALOAD 4
INVOKEVIRTUAL scala/Tuple2._2$mcD$sp ()D
DSTORE 6
L22
ALOAD 0
ILOAD 5
DLOAD 6
INVOKEVIRTUAL
org/apache/spark/mllib/stat/MultivariateOnlineSummarizer.org$apache$spark$mllib$stat$MultivariateOnlineSummarizer$$add
(ID)V
GETSTATIC scala/runtime/BoxedUnit.UNIT : Lscala/runtime/BoxedUnit;
ASTORE 8
```
Without pattern matching.
```
L17
LINENUMBER 100 L17
ALOAD 0
ALOAD 3
INVOKEVIRTUAL scala/Tuple2._1$mcI$sp ()I
ALOAD 3
INVOKEVIRTUAL scala/Tuple2._2$mcD$sp ()D
INVOKEVIRTUAL
org/apache/spark/mllib/stat/MultivariateOnlineSummarizer.org$apache$spark$mllib$stat$MultivariateOnlineSummarizer$$add
(ID)V
```
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