[Spark-8092][ml] Allow OneVsRest Classifier feature and label column names to be configurable.

[harsha2010]

The base classifier input and output columns are ignored in favor of the ones specified in OneVsRest.

[harsha2010]

@jkbradley please review. i didn't realize PredictorParams had no setters and setLabelCol, etc were in Predictor which OneVsRest does not extend. This means OneVsRest needs to expose setters for label, features etc that the underlying classifier needs.

[SparkQA]

Test build #34143 has finished for PR 6631 at commit 108d3d7.

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

[feynmanliang]

This LGTM. However, after reading this I feel that OneVsRestModel should extend ClassificationModel. I've created SPARK-8799 for that.

[jkbradley]

Sorry for the delay! Will review now. Jenkins test this please

[jkbradley]

I guess there are merge conflicts...but will comment anyways

[jkbradley]

Is this saying that the base classifier should output "predictionCol"? It probably should send output to a temp col, to be removed.

[jkbradley]

@harsha2010 We should document clearly that the input and output columns of the base classifier are ignored.

[SparkQA]

Test build #36433 has finished for PR 6631 at commit 108d3d7.

• This patch fails MiMa tests.
• This patch does not merge cleanly.
• This patch adds no public classes.

[jkbradley]

Ping : )

[harsha2010]

oops, thanks for reminding me...will update the merged patch tonight

[SparkQA]

Test build #38041 has finished for PR 6631 at commit b7024b1.

• This patch fails to build.
• This patch merges cleanly.
• This patch adds no public classes.

[jkbradley]

Could you please add doc to the "classifier" Param indicating that the base classifier input and output columns are ignored in favor of the ones specified in OneVsRest? Other than that, it looks good.

[SparkQA]

Test build #38178 has finished for PR 6631 at commit 6591dc6.

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

[jkbradley]

LGTM Would you mind adding a description before we merge this, e.g., to say that the OneVsRest input/output col params override the base classifier ones? Thanks!

[harsha2010]

@jkbradley , sure, do you mean in the Spark docs? The description is already in the code docs for the params of OneVsRest.

[jkbradley]

Oh, no, I mean the PR description (the first comment), to become part of the commit message.

[harsha2010]

@jkbradley , thanks., added the documentation to the first comment in this PR

[jkbradley]

Thanks! I'll merge this with master