[SPARK-14434][ML]:User guide doc and examples for GaussianMixture in spark.ml

[wangmiao1981]

What changes were proposed in this pull request?

(Please fill in changes proposed in this fix)

Add guide doc and examples for GaussianMixture in Spark.ml in Java, Scala and Python.

How was this patch tested?

(Please explain how this patch was tested. E.g. unit tests, integration tests, manual tests)

Manual compile and test all examples

[SparkQA]

Test build #57363 has finished for PR 12788 at commit 03ac9b4.

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

[wangmiao1981]

cc @yanboliang @jkbradley @MLnick @holdenk

[sethah]

"The MLlib" -> "The spark.ml"

[sethah]

I made a pass. @zhengruifeng can you please take a look as well?

[sethah]

outer println is unnecessary

[zhengruifeng]

@sethah It seems that these examples follow ml.kmeans's examples.
I agreed that it's better to keep in line with mllib's, especially the output information.

[SparkQA]

Test build #58009 has finished for PR 12788 at commit c844a6e.

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

[wangmiao1981]

retest it please.

[SparkQA]

Test build #58020 has finished for PR 12788 at commit 4b5152a.

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

[wangmiao1981]

@sethah @zhengruifeng @yanboliang I made changes to address comments.

[wangmiao1981]

retest this please

[SparkQA]

Test build #58033 has finished for PR 12788 at commit 4b5152a.

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

[sethah]

typo: "Creates"

[SparkQA]

Test build #58512 has finished for PR 12788 at commit aaea542.

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

[SparkQA]

Test build #58514 has finished for PR 12788 at commit 8f6f78f.

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

[wangmiao1981]

@yanboliang @MLnick @zhengruifeng @sethah simplified the example using kmeans data and addressed review comments.

[SparkQA]

Test build #58522 has finished for PR 12788 at commit 7175a1d.

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

[SparkQA]

Test build #58523 has finished for PR 12788 at commit 5259d4d.

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

[zhengruifeng]

Python API docs

[zhengruifeng]

nit, j -> 'i' to keep in line with scala example

[SparkQA]

Test build #58546 has finished for PR 12788 at commit eb9469e.

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

[wangmiao1981]

ping @MLnick @sethah @zhengruifeng @yanboliang

[MLnick]

@wangmiao1981 could you resolve merge conflicts by rebasing to master?

[MLnick]

we do setSeed here in the Python example but not in the Scala/Java examples. We should make it consistent (perhaps remove the setSeed here)

[MLnick]

A few other minor comments, otherwise LGTM

[SparkQA]

Test build #58645 has finished for PR 12788 at commit f56344b.

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

[wangmiao1981]

@MLnick I made changes accordingly. Thanks!

[MLnick]

Merged to master/branch-2.0. Thanks @sethah @zhengruifeng for the review!