[ML] modify validateParams method of org.apache.spark.ml.clustering.LDA.scala file, change docConcentration values from >= 0 to >=1

[endymecy]

change 285 and 296 line, modify "getTopicConcentration >= 0" to "getTopicConcentration >= 1"

[endymecy]

For EM optimizer, docConcentration values must be >= 1,so "getTopicConcentration >= 1" should be right.

[mengxr]

@endymecy Could you update the PR title to make it more specific?

[mengxr]

ok to test

[SparkQA]

Test build #52023 has finished for PR 11382 at commit 0b2723b.

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

[srowen]

@endymecy your title and description are basically a repeat of the diff itself, in English. This is redundant. What is the motivation for the change? that's what you should set out in the description. Normally we'd ask for a JIRA for a functional change.

[jkbradley]

One more thing: The checks should actually ensure that docConcentration and topicConcentration for EM are > 1.0 (strictly greater). Could you please make that update too?

[rxin]

Thanks for the pull request. I'm going through a list of pull requests to cut them down since the sheer number is breaking some of the tooling we have. Due to lack of activity on this pull request, I'm going to push a commit to close it. Feel free to reopen it or create a new one. We can also continue the discussion on the JIRA ticket.