[SPARK-11506][MLLIB]: Removed redundant operation in Online LDA implementation

[a1singh]

In file LDAOptimizer.scala:

line 441: since "idx" was never used, replaced unrequired zipWithIndex.foreach with foreach.

•  nonEmptyDocs.zipWithIndex.foreach { case ((_, termCounts: Vector), idx: Int) =>
  

•  nonEmptyDocs.foreach { case (_, termCounts: Vector) =>
  

[hvanhovell]

Could you add the number of the JIRA ticket this relates to? See other PRs for an example.

[srowen]

@a1singh looks trivial, but OK. This isn't quite how you propose changes; this isn't a descriptive title for example. Please read https://cwiki.apache.org/confluence/display/SPARK/Contributing+to+Spark
Please also see if you can find other instances of the same problem that can be optimized.

[a1singh]

@hvanhovell started a JIRA request and added the number to the title of this PR. In future, other similar micro-changes in MLLIB can be linked to this JIRA.

@srowen thanks for the link. I checked other files under Clustering, and they seem to be fine, with respect to this optimization.

[SparkQA]

Test build #1987 has finished for PR 9456 at commit ba0879b.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[srowen]

Merged to master

[a1singh]

Thanks @srowen @hvanhovell

I would be glad to help with other activities.