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https://issues.apache.org/jira/browse/MAHOUT-300?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12836452#action_12836452
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Ted Dunning commented on MAHOUT-300:
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Huh.... some of those times are a little surprising.
For DotProduct and CosineDistanceMeasure, SequentialAccessSparseVector is 3x
faster than RandomAccessSparseVector and 8x faster than DenseVector. There the
world is good.
But for SquaredEuclideanDistanceMeasure and TanimotoDistanceMeasure, there is
little difference while for ManhattanDistanceMeasure,
SequentialAccessSparseVector is slower than RandomAccessSparseVector.
Is it just that for these last 3 distances the sequentiality has not been taken
into account?
{noformat}
DotProduct
Rate = 3877.9443 MB/s Rate = 9846.534 MB/s
Rate = 31736.123 MB/s
org.apache.mahout.common.distance.CosineDistanceMeasure
Speed = 1690.1599 /sec Speed = 3366.8774
/sec Speed = 12309.282 /sec
org.apache.mahout.common.distance.EuclideanDistanceMeasure
Speed = 2913.8206 /sec Speed = 5868.9404
/sec Speed = 8209.688 /sec
org.apache.mahout.common.distance.ManhattanDistanceMeasure
Speed = 867.9127 /sec Speed = 2435.4307
/sec Speed = 1048.7443 /sec
org.apache.mahout.common.distance.SquaredEuclideanDistanceMeasure
Speed = 3387.1472 /sec Speed = 7091.4087
/sec Speed = 8785.509 /sec
org.apache.mahout.common.distance.TanimotoDistanceMeasure
Speed = 1803.4031 /sec Speed = 3873.8967
/sec Speed = 6844.7017 /sec
{noformat}
> Solve performance issues with Vector Implementations
> ----------------------------------------------------
>
> Key: MAHOUT-300
> URL: https://issues.apache.org/jira/browse/MAHOUT-300
> Project: Mahout
> Issue Type: Improvement
> Affects Versions: 0.3
> Reporter: Robin Anil
> Fix For: 0.3
>
> Attachments: MAHOUT-300.patch, MAHOUT-300.patch, MAHOUT-300.patch,
> MAHOUT-300.patch, MAHOUT-300.patch
>
>
> AbstractVector operations like times
> public Vector times(double x) {
> Vector result = clone();
> Iterator<Element> iter = iterateNonZero();
> while (iter.hasNext()) {
> Element element = iter.next();
> int index = element.index();
> result.setQuick(index, element.get() * x);
> }
> return result;
> }
> should be implemented as follows
> public Vector times(double x) {
> Vector result = clone();
> Iterator<Element> iter = result.iterateNonZero();
> while (iter.hasNext()) {
> Element element = iter.next();
> element.set(element.get() * x);
> }
> return result;
> }
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